centripetal pathway from the bladder thespinal cord · the afferent pathway in the spinal cord of...

J. Neurol. Neurosurg. Psychiat., 1951, 14, 262.

THE CENTRIPETAL PATHWAY FROM THE BLADDER ANDURETHRA WITHIN THE SPINAL CORD

BYP. W. NATHAN and MARION C. SMITH

From the Neurological Research Unit of the Medical Research Council, The National Hospital, Queen Square, London

While clinical and experimental facts aboutlesions of the spinal cord and the functioningof the bladder have been collected for more than50 years, knowledge remains inadequate concern-ing the afferent pathway from the bladder withinthe central nervous system of man. In 1906,von Frankl-Hochwart and Zuckerkandl wrotein their monograph on neurological disorders of thebladder: " Sehr gering ist noch unser Wissenuber die spinalen Leitungsbahnen; am Menschenist man nie uiber unbeweisbare Hypothesen hinausge-kommen ". They also stated specifically thatnothing was known about the ascending tractsconcerned with conduction from the bladder. In1919, Muller still found it necessary to write:" Ober die Bahnen im Ruickenmark, durch welchedie Empfindungen von den Blasenkontraktionenzentralwarts geleitet werden, und uber die Stelleim Gehirn, wohin diese projeziert werden, sindwir noch vollig im Unklaren ". In 1939, Bingand Haymaker wrote: " The pathways whichthe afferent fibres follow to reach the consciouslevel are not known ".

Barrington investigated the problems of localiza-tion of the central nervous pathways by means ofexperimental lesions in animals. In 1925, hereported the results that he had obtained by makinglesions in the midbrain of the cat; he found that"destruction of the midbrain from the ventralhalf of the side of the posterior end of the aqueductoutwards to just beyond the mesencephalic rootof the fifth nerve is followed when the lesion isbilateral by a permanent loss of consciousness ofwanting to micturate or defaecate ". In 1933,he reported further Work, showing the position ofthe afferent pathway in the spinal cord of the cat.He concluded that the whole or a large part of thecentripetal pathway must lie in a superficial areain the posterior part of the lateral columns, notreaching as far posteriorly as to abut against theroot entry zones. This region is shown in Fig. 1

Fig. 1.-Diagram of transverse section of spinal cord of cat. Thearea within which the centripetal bladder pathway lies is shownby stippling.

(a reproduction of Fig. 4 of Barrington's paper).Among the many clinical papers which are con-

cerned with the effects of lesions of the centralnervous system on bladder function, we know ofonly one which considers the afferent tract, thatby McMichael (1945), who reported the case of apatient who had lost sensation of bladder fullness.Sections of the spinal cord showed an area ofdegeneration anterior to the posterior horns inthe lateral columns. This area could not be tracedcranial to the thoracic region.

It is the purpose of this paper to present evidenceconcerning the location within the human spinalcord of the centripetal pathways (1) from thebladder, conveying impulses subserving (a) thedesire to micturate, (b) pain; and (2) from theurethra, conveying impulses subserving (a) touch,(b) pain, (c) temperature, and (d) proprioceptionfrom the muscles working in association with theurethra.

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CENTRIPETAL PATHWA YS WITHIN THE SPINAL CORD FROM THE BLADDER 263

Material

The material consists of 27 patients with lesions ofone or both antero-lateral columns of the spinal cord, andof three control patients, in whom these regions wereintact. Of the 27 patients, 24 had the operation of antero-lateral cordotomy performed for pain associated withcancer; one had this operation performed for thepain of tuberculous cystitis; and two patients hadarterial thromboses, one of the anterior spinal artery,and one of a posterior inferior cerebellar artery. Thepatients of the control group suffered from amyotrophiclateral sclerosis, subacute combined degeneration of thecord, and from Friedreich's ataxia. Histologicalpreparations have been made of 18 of the first group,and of all of the control groups.The operations of spino-thalamic cordotomy were

carried out for the relief of pain. The area of cordtransected, although planned to give the maximumrelief of pain, was varied to some extent from patientto patient. Seventeen of the patients were under thecare of Mr. McKissock or in the wards of the ResearchUnit ; they were fully investigated on several occasionsbefore and after operation. Through the kindness ofother neurosurgeons, other patients have been madeavailable to us; these cases have been investigated onlyafter operation. As the surgical interference has beenundertaken for the relief of pain associated with cancer,the survival period has been relatively short ; thereforeit has been possible to determine histologically the extentof the incision in the cord and the resulting ascending anddescending degeneration.

InvestigationClinical.-The investigation falls into two sections,

clinical and histological.

Bladder Sensation.-The main clinical evidence is basedon day to day observation of the patient. Specialinvestigations often added little to what was obvious onclinical observation. For example, if a patient is lyingin bed with the bladder distended so that it can be feltas a dome between the pubic crest and the umbilicus,and the patient is quite unaware of this state of extremedistension, it can be concluded without further investiga-tions that the patient has lost the sensation of needing tomicturate and that of pain from over-distension of thebladder. Wherever possible, however, conclusions drawnfrom these observations were confirmed by observingwhat occurred under the controlled conditions ofcystometrography.

Immediately after the operation of spino-thalamiccordotomy, which, when performed bilaterally, causedretention of urine, the bladder was allowed to becomedistended in order to find out what sensations wereexperienced; catheterization was then performed torelieve this distension. Cystometrography was carriedout before and after operation. It was possible in thisway to record the conditions of pressure and fluidcontent which gave rise to any form of vesical sensation,and to compare records made before and after theoperation. The patients were asked to report any

sensations they experienced. The evidence thus dependsentirely on the subjective experience of the patient.The method of cystometrography employed was

designed to imitate as closely as possible the normalfilling of the bladder. After the bladder had beenemptied by catheterization, fluid-a warmed solution ofproflavine sulphate, 1 in 10,000 in normal saline-wasallowed to flow through a catheter into the bladder, at arate of one to two drops a second. The pressure at whichthe fluid entered the bladder was the same as that whichthe bladder exerted on its contents.A drawing of the apparatus is shown in Fig. 2. The

proflavine solution, stored in a graduated reservoir,passed through a drip-bulb, the rate of flow beingadjusted by a screw-clip. The drip-tube was connectedby three channels; first to the catheter, which hadpreviously been fixed in the bladder, secondly to amanometer, consisting of an upright glass tube, opento the air, and thirdly to a hollow C-spring, attached tothe end of which was an ink-writer. The pressure in thebladder at any given moment could be read from theheight of the fluid in the manometer. While the recordwas being made, the patient was invited to say whatsensations, if any, were experienced. It will be notedthat the amount introduced into the bladder from thereservoir was not necessarily the same as the fluid con-tents of the bladder, because the kidneys were secretingurine throughout the investigation. The total fluidcontent was obtainable only at the end of the investiga-tion, when the total contents withdrawn by catheterwere measured.

FIG. 2

Pain sensibility in the bladder was investigated invarious ways. During cystoscopy, which was performedbefore and after operation, attempts were made toinduce pain by indenting and stretching the neck of thebladder, the trigone, the bladder walls, and the uretericorifices. The loss of painful sensation, when the bladder



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P. W. NATHAN AND MARION C. SMITH

was allowed to become distended after the bilateraloperation, was taken to indicate that the pathwaysubserving the pain of bladder distension had beendivided. In some patients, the spino-thalamic cordotomyhad been performed for a painful condition of thebladder; if the operation relieved this pain, then thepathway subserving pain in the bladder must have beendivided. In other patients, who have had the operationof bilateral cordotomy, a condition of the bladder hasbeen found post-mortem that is known to be painful;such are inflammation of the viscus and ulceration. Asthere were no complaints of pain during life, it wasconcluded that the operation cut the tracts conveyingimpulses interpreted as pain. It is therefore possible todetermine by analysis the centripetal pathway subservingpain caused by a variety of bladder conditions.

Urethral Sensation.-From the normal urethra im-pulses are transmitted subserving sensations of touch,of warmth and cold, and of pain. In addition, one of themain sources of sensation associated with micturition isproprioception from the muscles that act in associationwith opening and closing of the sphincter. The sensationsof pain, touch, and of forceful opening of the sphincterby a catheter or cystoscope were noted before and afteroperation. The patients were also asked to observewhat they felt when they passed urine voluntarily orinvoluntarily.As it is not yet definitely known whether the bladder

mucosa is sensitive to thermal stimuli, and as theurethral mucosa definitely is sensitive to such stimuli,no attempt was made here to differentiate the site oforigin of the thermal sensations experienced. Proflavinesolution at various temperatures was introduced into thebladder through a urethral catheter before and afteroperation. The patient was asked to comment on thesensations experienced.

Histological.-Fixation of the spinal cord was initiatedas soon after death as possible. In the majority of casesthe cord was fixed in situ; 20%h formol saline wasinjected into the cisterna magna, while cerebrospinalfluid was drained by lumbar puncture; after a few hoursthe brain and cord were removed, and the necropsycompleted. Fixation of the brain and cord in 20%hformol saline was continued for 10 to 18 days, and thecord was then divided into segments. To demonstratedegenerated pathways, the techniques used were theSwank Davenport modification of the Marchi method,the Kulchitsky modification of the Weigert Pal method,and Gros' silver method. The blocks were embeddedin celloidin.

Sections were taken at several levels of each segmentof the cord, and in areas of special interest, serial sectionswere prepared. In the majority of cases the modifiedMarchi method was found to give satisfactory results,even when the interval between operation and death wasabout a year (Smith, 1951). Silver and Weigert Palpreparations were used to confirm the findings shownby Marchi staining. It was considered necessary to usethe silver method in order to show destruction of axiscylinders, for the myelin stains may not demonstratethe absence of small, poorly myelinated fibres.

Clinical EvidenceIn normal subjects, the vesical pressure at which

sensations are experienced varies considerablyfrom time to time, and from subject to subject.Also, the sensations experienced are related to therate of filling, and to the rate of change of pressure.However, in all normal subjects, when the bladdercontains a certain quantity of fluid, a stage is reachedwhen there is a definite desire to micturate. Inthe present investigation, 20 healthy men and womenwere examined by the method of cystometrographydescribed. An average of the figures from thesesubjects showed that there was a definite, insistentdesire to micturate when the bladder contained340 ml. of fluid at a pressure of 14 cm. of water.The clinical evidence is presented in a condensed

form as Table I. Those cases marked with anasterisk are mentioned in further detail.

Case 9.-Immediately following the second stage of abilateral sympathectomy this patient developed athrombosis of the anterior spinal artery. This causedcomplete analgesia throughout the right side below thesecond lumbar dermatome and throughout the left sidebelow the third lumbar dermatome. There was retentionof urine; the patient had no normal desire to micturate,and no pain with the retention. Eventually she got afeeling whenever her bladder was distended, which shedescribed as follows: " My tummy feels uncomfortable;it is a feeling of wind really; I cannot tell which it is;it is not the normal feeling of having to empty thebladder, only an uncomfortable feeling in the tummy ".She could feel a catheter being passed, but it was entirelypainless. Often, when bed-pans were being taken roundthe ward, she would get a normal feeling of needing tomicturate, but it lasted only a minute or two, andwould be unrelated to the state of distension of her ownbladder.

Case 10.-This case showed much degeneration of allafferent pathways; it is included in this series, as it isadequate for supplementary evidence, and because thispatient, a man of 21, gave such good descriptions of hissensations. Following the operation of bilateral cordo-tomy, pain sense was diminished below the elevenththoracic dermatome on the right, and absent throughoutthe left below the tenth thoracic dermatome. Theiewas retention of urine, but the patient was unaware ofthis. He soon found, however, that he could tell whenhis bladder was full, as he got a sensation which hedescribed as follows: " When my belly feels very full, asthough I have eaten a lot, I know I have to empty mybladder ". The normal sensation that his bladderneeded emptying had gone. This patient later explainedthat the feeling of abdominal fullness which he got whenhis bladder was full, seemed to him to be unrelated to hisbladder; it seemed to occur vaguely and generally.within his abdomen; sometimes this sensation alsooccurred when his abdomen was full of wind or hisrectum full of faeces; in itself the sensation was non-

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CENTRIPETAL PATHWA YS WITHIN THE SPINAL CORD FROM THE BLADDER 265specific; he learnt by experience that it usually meantthat his bladder needed emptying. When he was beingcatheterized, he felt nothing until the tip of the catheterpassed the membranous urethra, when he explained thathe had merely the feeling of the presence of somethingin that region ; it was a painless sensation. Beforeoperation catheterization had been painful, and hadleft a soreness afterwards.When micturition became automatic he would get,

just before it began, a tingling and itching in the penis.This sensation could also be induced by giving 0 25 mg.of carbaminoyl choline (carbachol), which would causeurine to be voided.

Case 18.-This patient before bilateral cordotomy hadsuch terrible pain every time he micturated that oftenhe had to be given " trilene " by inhalation. His bladderwas shrunken, and he had to micturate every five or 10minutes. A bilateral antero-lateral cordotomy wasperformed by Mr. O'Connell under local anaesthesia.By the time the cord was exposed, the patient had amost urgent desire to micturate and much pain in thebladder. When the cord had been bilaterally incised,the pain and the desire to micturate were simultaneouslyrelieved. After the operation, which caused analgesiabelow the fourth thoracic dermatome, the patienteventually had to empty his bladder only once everyhour. He was able to do this while carrying on aconversation, a state of affairs quite unlike that whichhad prevailed before the cordotomy.

Case 19.-Following bilateral cordotomy there wascomplete analgesia throughout the body below the fourththoracic dermatome. On the evening of the day ofoperation, the patient was catheterized on account ofretention of urine: he noted that he felt the passageof the catheter, although it was painless, whereas beforeoperation it had been so painful that it had almost to begiven up. On the next day, he was found with hisbladder full and distended, so that it could be felt abovethe pubic crest. He was moaning on account of thepain of it. He said that the bladder felt full, althoughthe sensation was a new one, and not the normal feelingof urgently needing to micturate ; it differed in that itwas not felt in the penis or perineum, but was situatedonly in the lower abdomen, above the pubic crest. Whenhis distended bladder was pressed on through theabdominal wall, the pain was increased. It was foundthat he got no pain on having his testicles squeezed, hispubic hair vigorously pulled, and that pinprick on hispenis and scrotum was felt only as touch. This lowerabdominal pain was associated with bilateral frontalheadache; both pain and headache went when thebladder was emptied. He gradually developed moresensation in the urethra. When the catheter was passed,he got a tickle in the penis ; sometimes he got a prickingor irritation at the meatus; as it passed along themembranous urethra he got a desire to micturate, andthis feeling always became intense when the tip of thecatheter reached the membranous part. Then he foundthat whenever micturition was about to begin, he wouldget the same pricking feeling in the penis ; he also gotit when he strained to micturate, and also if too big a

c

catheter reached the posterior urethra. He had nonormal feeling that his bladder was full and no normaldesire to micturate; when it was very full, he sometimesgot a pricking sensation above the pubic crest, whichwould go away as urine was let out. Four weeks afterthe operation, he again had some pain in his bladderand in the tip of the penis; the bladder contained 640 ml.of urine. He stated that this pain was the normalsensation one has when one needs urgently to micturate.Case 20.-Following unilateral cordotomy there was

analgesia throughout the right side of the body belowthe fifth thoracic dermatome. There was for a fewdays after the operation " not a pain, well, yes-a pain,but only slight " immediately above the pubis and justto the left of the midline, when he needed to micturate.He then found that he had the feeling of needing tomicturate only on the left side, the side of the body thatwas normally innervated. Later, he felt it mainly on theleft, and eventually he noticed no laterality in thesensation, having a normal sensation underlying thedesire to micturate.

Case 23.-Following deep x-ray treatment, thepatient got severe pain in the left thigh and knee; healso got a strange feeling of warmth running down theleft thigh when he micturated ; this was accompaniedby frequency of micturition. During cystoscopy, thefollowing observations were made. As the cystoscopereached the posterior urethra, he had a desire to mic-turate; he got the same desire when this part of theurethra was stretched. The bladder was filled at apressure of 50 cm., and when it contained 600 ml. hegot an urgent need to micturate. Some of the fluid wasreleased ; then rubbing of the trigone with the cystoscopeagain brought on the desire to micturate. A uretericcatheter was then put into the right ureter ; this gavehim the feeling of a pricking on the right side of thepenis ; as the ureteric orifice was stretched, the prickingfeeling became a continuous pain ; as the catheter waspushed up the ureter, it felt as though " you are pushingin a tender place on the right ". On the left half of thebladder, there were many telangiectases, doubtless dueto radiotherapy; the slightest touch over these with thetip of the ureteric catheter caused severe pain, felt eitheron the left or just to the left of the midline or centrally.The left side of the bladder was so tender, that searchfor the ureteric orifice had to be given up.

Following unilateral cordotomy there was totalanalgesia throughout the left side below the twelfththoracic dermatome. Cystoscopy was repeated threeweeks after operation. The bladder was filled at apressure of 50 cm. ; when 700 ml. had been put in, thepatient got an urgent desire to micturate, only on theright side. The ureteric catheter was pressed into thelateral walls; nothing was felt on the left, a slight painwas felt on the right. The telangiectases, so sensitivebefore the operation, were rubbed vigorously (theyoccurred only on the left side of the bladder); nothingwas felt. Both ureteric orifices were then stretched asmuch as possible by means of the ureteric catheter;nothing was felt on the left; on the right, penetrationcaused a slight feeling of pressure, stretching caused a



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TABLE I

OBSERVATIONS ON BLADDER AND URETHRAL SENSATION MADE ON 27 PATIENTS WITH

Lesion in Cord Dermatome below Sensation Under- Bladder Pain_____- l lwhich Analgesia lying DesireI

is Present to Micturate Present Due toon Pathological

Plate Sr Extreme ConditionCase Sx and Blt Un-ivlDisten- of Bladder

Diagnosis Un-valNec-No. Fig. eral lateral Other in ropsy nfterCorordo- rdo- Lesion Days Right Left nAb- Pre- Uni- r

I ~~~~~tomy tomy senthsentelateral renc Pre- Pre-of sent sent'

Spinfal befprel afterLesion Lesion Lesion

1 F Plate I Carcinoma of + - | 66 6th Th. 9th Th. -I- + - -Fig. 3 cervix

2 M Carcinoma of 75I5I Ith. 7thTh. +- -

prostate

3 F Carcinoma of 23 10th Th. 10th Th.cervix 10 Ohh Ohh1A

4 M Carcinomaof + 80 6th J6 TthlTh.± --+|pancreas ___ ___ _ ___

S F Plate I Carcinoma of 230 +1 12th Th. 12th Th. + -- - - - -Fig. 4 cervix

6 F Fig.5______PlateC a_ 42 9th Th. 5th L. + - - - - -Fig. 5 cervix

7 F____ Carcinomaof 24 +10 th Th. 8th Th.-cervix 2' ti n 8hh

8 F_ Carcinoma of 23- 6th Th. 10th Th. ± -colon- -

9* F Anterior - - Anterior 231 - 2nd L. 3rd L. -+ - - - -I ~~~~spinal 'two

artery thirds of___|-___ thrombosis cord

10* M Plate II Chondro- - - 141 - 11th Tb. 10th Tb. _ -Fig. 6 sarcoma of

ilium

11 F Carcinoma of + - _ _ _ 240 2nd L. 9th Th. ±rectum

12 F __ Carcinjoma of + 118 5th Th. 5th Th. + - -

13 M Plate II Secondary . -_ - 109 V 12th Th. 12th Th. -I- - -Fig. 7 carcinoma

in ischium.Primarynever found

14 F Melanoma - - 162 12th Th. 12th Th. + --

___ ___ _____ '______ _____- _ _7515 F Carcinoma of - - 5 9th Th. 10th Th. +

vagina16

17

F

F

Carcinoma ofcervix

Carcinoma ofcervix

+

240

165

10th Th.

Ist. S.

10th Th.

9th Th. +-

* Cases marked with an asterisk are given in text in further detail.

-

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LESIONS OF THE ANTERO-LATERAL COLUMNS AND THREE PATIENTS WITHOUT SUCH LESIONS

Presence of Abnormial Sensation Sesto on .aheeizto IThermal CmetRelated to Bladder Fullness SensationonCteriaon Sstonom ns

-Frontal headache Felt catheter-no pain Necropsy examination showed in the middle of the trigone a sloughingulcer 1-5 cm. diameter, the floor of which was formed by a thinmembrane separating it from the anterior wall of the carcinomatouscervix. Mucosa, particularly of trigone, reddish purple.

Vague feeling of abdominal Felt catheter pass-no pain Necropsy examination showed that the carcinoma of the prostate hadfullness invaded the bladder ; the mucosa wvas grossly infecied, but not

ulcerated.

An accentuation of parses- Unpleasant irritation in urethra Unpleasant irritation was felt in vagina and deep in pelvis wheneverthesiae of vibration in lower and vagina ; throbbing pul- she had a vaginal douche, or if she was catheterized, or if her rectumlimbs sating sensation in urethra was very distended. The feeling was so diffuse and vague that it gave

her no indication which of these stimuli was causing it. Necropsy________ _________ ___ ~~~~~~~examination showed that the bladder was grossly infected. _

An ache across lower abdomen With eyes shut, he felt glans Necropsy examination showed a normal bladderbeing cleaned, catheter intro-duced into meatus ; nothingelse ; no pain

Felt catheter-no pain Necropsy examination showed that the carcinomia had invaded the_______________________________________________________________________ ______________________ b a dr_______________________________bladder______________ _______________

Necropsy examination showed that the carcinoma had invaded the~~~~~~~~~bladder

- ~~~~Felt nothing Necropsy examination showed that the carcinoma had invaded thebladder

Vague feeling of abdominal dis- Catheter felt only on left side The feeling of abdominal distension was so vague that she never knewtension of urethra (analgesia being whether its cause was flatus or a distended bladder

incomplete on the left)

See text Felt catheter pass-no pain -

See text See text

"A sort of warmi feeling" in Catheter scarcely felt-no pain - Necropsy examination showed that the carcinomia surrounded the necklower abdomen and perineum of the bladder and had invaded the vesical miuscle

Feelings in lower abdomen Felt nothing

It feels heavy" in lower Catheter felt-no pain. 12 daysI Necropsy examination showed that the carcinoma had invaded theabdomen after operation he got a slight i bladder

Idesire to micturate when theI tip of the catheter reached the

posterior urethra

She felt she could not get a full Felt catheter-no pain - One month after operation she found that she knew immiediately beforebreath as bladder was filled, automatic micturition that the act was about to occur. She was notWhen bladder was very full, sure whether this was a normal sensation underlying the desire toabdomen felt distended. micturate or not. When the bladder was caused to contract reflexly,

by suddenly raising the pressure, she got a sensation that she waspassing urine, or was about to pass it, or that she wanted to pass it.

My stomach feels full" Felt nothing

Slight tingling in bladder Felt nothingregion

- ~~~~Before operation severe pain on Cystoscopic examination showed that the carcinoma had wuaded the-having any instrument passed bladder, in the neighbourhood of the uretersinto urethra. After operationthis pain could not be induced.Could feel urine passing

Conttinued o verleaf'



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TABLE I-

IDermatome belowwhich Analgesia

is Present

Right Left

Sensation Under-

I lying Desire

I so Micturate

Ab- Pre- IUni-sent sent lateral

Bladder Pain

IPresentI Due toon Pathological,

Extreme ConditionDisten- of Bladdersion

after

Occur- Pre- Pre-rence sent sentof before after

Spinal Lesion Lesion~LesionI

18* MjTubercerulous -+ <4- 4th Th. 4th Th.~ + - +cystitis years

19* M PlatelIt Carcinomaof- 123 +t 4th Th. 4thlTh.. + -IFig. 8 bronchus _ _

20* M Plate III Carcinoma of - + - 110 -1 5th Th. --Fig. 9 bronchus__

21 IM Plate III Chondro- + - 159 +~ 9th Th. 5th Th. +--I Fig. 10 sarcma of

22 M Plate III Carcinomaof± - 154 + - Ist S. - + - -Fig. II rectum ______ ____

23* MI Carcinoma of - +I - 358 - 2th Th. - + + +~colon

24* M 1 Posterior in-I - etx 101- Blw - -fierior cere- Imandi-bellar artery buathrombosis divi-1

25 F Carcinorniaof1 ± OD-5 - Ist S. 9th Th. - -i-vagtna

26 M Osteoarthritis' + < 6th Th.of hip-joint years

27 Fj -Painfulampu- -- ~<21 6th Th.ltation yearsstump

28 M PlateIV Motor neu- - - Degenera- <2 -I- -+-Fig. 12 ron disease tion of years

pyra-midal

~~~~tractI

29 F PlatetIV Subacute 1- - Posterior 1 + - - -- - - -Fig. 13 combined columns year

degenera-tion of the

30 F Plate IV Friedreich's - Pyramidal 29 ±+Fig. 14 ataxia tract; years

posteriorcolumns:

I spmno-cerebellar

-.________ ~~~~~~~tracts _ _ _ _ _ _ _

* Cases marked with an asterisk are given in text in further detail.

;Plate

and

Fig.Nos.

Lesion in Cord

Case SexNo.I I DiagnosisBilat-

eral

Cordo-

tomy

Uni-lateralCordo-tomy

Other

Lesion

Sur-vivalin

Days

Nec-ropsy



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(Con/tiniued)

Presence of Abnormiial Sensation ThermalRelated to Bladder Fullness Sensationo Cahtrztoehra

Vague feeling of abdominal Pricking and irritation atfullness and pricking in penis meatus; tickle in penis

- Catheter not felt on right

- Catheter hurt less than before Although this was a bilateral cordotomy, the incision on the left sideoperation of the cord was made purposely superficial and somewhat anterior.

The analgesia was typical of division of one spino-thalamic tract.After the first 10 days, the sensation underlying the desire to micturatewas normal.

-_ _ Necropsy examination showed a normal bladder, not invaded bycarcinoma.

- Catheter not felt on left Absenton an-algesicside

v_ Catheter not felt on right Absenton an-

* algesicside

Uncomfortable aching above Catheter not felt on left The analgesia was total only unilaterally: on the right side of the bodypubis there was only diminution of pain below the first sacral dermatome.

By the time the sensation of pain recovered to the state of diminutionof pain, the patient had regained the sensation underlying the desire tomicturate; this was felt only on the side of the body that was hypo-algesic. This sensation was diminished, as shown by the fact that840 ml. of urine in the bladder, distending it so that it was felt asa dome above the pubis, caused her little distress, the little sensationshe experienced was felt only on the right.

- The patient noticed no change in the desire to micturate until his bladderbecame over-distended; then he realized that he had this sensationonly unilaterally.

The patient had no change in the sensation of needing to micturate undernormal circumstances, but as soon as the desire became at all urgent,she noticed that she felt it more on the side of the body with normalsensation.

Case included as control

Case included as control

-_ Case included as control



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pain felt on the right. Pressure with the cystoscope onthe trigone caused a severe urge to micturate, felt onlyon the right; pressure on the bladder neck in themidline caused a feeling of pressure on the right side ofthe pubic crest. The ureteric catheter was then pushedhard in the midline into the wall of the bladder at thejunction of the posterior wall and the dome; this causedno sensation on the left, and a moderate pain just to theright of the midline of the pubic crest. Strong pressurewas then applied with the cystoscope on the left side ofthe bladder neck; this caused no sensation on the left,but a sharp pain on the right, ofthe kind that accompaniesan urgent need to micturate. It will be realized thatactually pressure in this region cannot be made uni-laterally, so that pressure on the left must have pulledon and distorted the right half of the bladder neck andposterior urethra. Two days later cystometrography wascarried out. The catheter was felt only on the right.All the sensation that he needed to micturate, andfinally, the urgent desire to micturate, were felt only onthe right. When it was pointed out to the patient thatit was difficult to imagine such a sensation, he insistedthat it was so, saying that he felt the full state of hisbladder on the right side of his penis, on the right sideof his perineum, and generally in the pubic region on theright. When 675 ml. of fluid had been run in, the rate offlow was increased. The patient, who was an excellentobserver, said that he could feel his bladder getting fuller,almost drop by drop, but only on the right.The subjective symptoms related to micturition referred

to above ceased after the operation.

Case 24.-This patient was seen a few months afterthe onset of a thrombosis of the left posterior inferiorcerebellar artery. As he is still alive, no histologicalevidence about the extent of the lesion has been obtained.Although there may be minor differences in the regionof the tnedulla involved by thrombosis of this artery,all cases show involvement of the spino-thalamic tract.In this patient pain and thermal sensation throughoutthe right side of the body below the third division of thefifth cranial nerve were absent. In reply to questioning,the patient stated that he had noticed no change in anyway in micturition, and that he had the usual sensationunderlying the desire to micturate. However, whencystometrography was carried out, he was asked to payattention to his sensations. He then found that he feltthe sensation underlying the desire to micturate only andentirely on the left ; it was located mainly in the leftside of the penis. From that time onwards he realizedthat he experienced this sensation only on the left side,and he found that when he passed urine he felt it passingonly on the left. When cystoscopy was performedlater, he felt the instrument being passed only on theleft. The posterior urethra was then stretched byelevation of the bridge on the instrument: on the rightthis caused no sensation; on the left, it caused a feelingof pricking in the left of the penis. Catheters were thenpushed into the ureteric orifices, and the orifices andlower ends of the ureters were stretched; somethingwas felt on the left, nothing on the right. A uretericcatheter was pushed into the wall of the bladder on the

right side, so as to deform the whole viscus ; this causedsome sensation, located to the right. It should be pointedout, however, that by this time, there was some recoveryof pain conduction, so that severe stimulation of theskin on the right with a pin caused a slight sensation ofpain.From Table I, it will be seen that many of those

patients who had lost the normal sensation under-lying the desire to micturate experienced othersensations related to bladder filling and emptying.These sensations may now be considered, underthe following headings: (a) abnormal sensationsrelated to bladder fullness; (b) sensations at adistance; (c) urethral sensations and the sensationunderlying the desire to micturate.

Comments on Clinical Evidence(a) Abnormal Sensations Related to Bladder Full-

ness.-Repeated observations were made by thepatients who had lost the normal sensation under-lying the desire to micturate on a certain newsensation in the lower abdomen-which might becalled a substitute sensation-by means of whichthey were made aware of the state of tension in theirbladders. It consisted of a vague feeling of fullness,poorly localized, usually described as occurring" down below ", or " in the stomach " (" stomach "

being used by many people in this country as aeuphemism for belly or abdomen). Further com-ment on this sensation will be made in the discussion;it suffices to state here that it was never confusedwith the normal sensation by any patient.

(b) Sensations at a Distance.-Sensations at adistance are those sensations, such as frontalheadache, the feeling one is about to shiver, orthat one cannot take a deep breath, which havebeen observed and investigated by Guttmann andWhitteridge (1947) in cases of complete divisionof the cord. As has been shown, such sensationsoccurred also in these cases, where the cord wasnever divided, and where only the afferent pathwayfrom the bladder was divided.

(c) Urethral Sensations and Sensation UnderlyvingDesire to Micturate.-It is known that in thenormal subject the sensation of having a fullbladder that needs emptying is related to a rise intension of the bladder wall. But in some normalsubjects various forms of stimulation of the urethracause a desire to micturate. Such people experiencethis desire when a catheter or cystoscope is passedalong the urethra, and particularly when its tipstretches or deforms the membranous and prostaticparts. In such circumstances, however, there isno rise in bladder tension. Yet these subjects mayfind that this sensation is the same as that which

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CENTRIPETAL PATHWAYS WITHIN THE SPINAL CORD FROM THE BLADDER 271

they experience when their bladders are full andunder tension, or they may find that it consistsof only the urethral component of this sensation.

In this investigation, the sensation underlyingthe desire to micturate has been separated as faras possible from sensations arising in the urethra.In those patients who had bilateral lesions of theantero-lateral columns, a comparison has beenmade between the sensations experienced on

catheterization and the sensations experienced asautomatic micturition was about to start. (Allthese patients had lost voluntary control of micturi-tion; this aspect of the subject will be consideredin a subsequent paper.) These sensations are listedin Table II.

It will be seen from this Table that those patientswho had no urethral sensation or none but touchand stretch (the feeling of the catheter being passedor of it passing the sphincter, but without pain)had no sensation informing them of the imminenceof micturition, or giving them the desire to micturate.The subject of Case 13 had the same sensation on

being catheterized as she had before micturition.And the subject of Case 19 also had the same sensa-tion on these occasions, although there were otheradditional sensations as the basis of a desire tomicturate. It is to be noted that, with the exceptionof the subject of Case 16, where the sensation was

probably the substitute sensation, these sensationssubserving the desire to micturate all came on

immediately before micturition occurred; whereasthe normal sensation subserving the desire tomicturate comes on many minutes before thesubject chooses to micturate. It is suggestedthat all these patients had in fact lost the normalsensation causing the desire to micturate, but,retaining much urethral sensation, some patientsinterpreted the sensations associated with changesin the urethral sphincter and/or stimulation of theposterior urethra as being the normal sensationof needing to micturate.

Histological EvidenceThe cases of which the clinical accounts have been

given above may be divided into groups, in orderthat common microscopical anatomical featurescan be extracted.To determine the position of the pathways, plans

of each case were drawn, showing the degeneratedareas at various levels of the cord. These plansfrom the different cases were then superimposed,and the smallest common area of degeneration ateach level was determined. All the 21 cases, ofwhich necropsy material was obtained, were usedto determine the afferent pathways. As manycases show similar areas of degeneration, only

TABLE II

SENSATIONS EXPERIENCED BY PATIENTS WITH BILATERAL

LESIONS OF ANTERO-LATERAL COLUMNS ON BEING

CATHETERIZED AND AT THE BEGINNING OF AUTOMATIC

MICTURITION

Case Sensation on Sensation OccurringNo. Catheterization Immediately before

Micturition

1 Catheter felt; pain- Noneless


3 Irritation and throb- Irritation and throbbing inbing urethra and vagina



6 Unknown None

7 Nothing felt None



10 Catheter felt; pain- Tingling and itching inless penis


12 Nothing felt None

13 Slight desire to mic- Slight desire to micturateturate

14 Catheter felt; pain- Feeling that she is about toless micturate, or that she is

passing urine, or thenormal desire to mic-turate

15 Nothing felt None

16 Nothing felt Slight tingling in region ofb.adder

17 Catheter felt; pain- Feeling that she is aboutless to micturate

19 Tickle in penis; Tickle in penis; prickingpricking at meatus; at meatus; desire todesire to micturate micturate; pricking

above pubis; feelingthat he is micturating;feeling that he is stop-ping himself micturating



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cases which are of particular value in delimitingthe tracts are shown in the photographs on PlatesI to IV.

In most cases the operation was performed atthe fourth, fifth, or sixth thoracic segments. Theposition and the extent of the incision were purposelyvaried. It is for this reason that the extent andarea of destruction of the cord at the level of theincisions differ greatly from side to side and fromcase to case.The degenerated area in the region of the opera-

tion is far more extensive than at higher levels;for the incisions made into the cord may destroynot only long ascending fibres, but also descendingand intersegmental fibres. Retrograde degenerationin these descending tracts usually does not extendcranially for more than about a centimetre; andso a true picture of degenerating ascending fibresis obtained cranial to this level.

Photographs of sections from representativecases are shown in Plates I to III. As far as possiblethe sections have been taken at comparable levels;in most cases they are from a mid-thoracic segment(usually the site of operation) and from lower andupper cervical segments. The considerable varia-tion in the size of the cords seen in the photographshad been observed also at necropsy.

Figs. 4, 12, 13, and 14 are of sections stained bythe Weigert Pal method (degenerating fibresunstained). Fig. 8c is a Gros' silver preparationshowing absence of degenerated axis cylinders.All other figures are of sections stained bythe Marchi method; degenerating fibres stainedblack.

Group 1 (a).-This group consists of cases inwhich the pathways conducting the sensation of afull bladder and pain from the bladder are bilaterallydivided: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18; Case 19 will be considered in thisgroup.

Cases 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,and 19 were examined histologically. Photographsof representative sections from six of these 15 casesexamined histologically are shown in Plates I and II.In 13 of these cases there is no evidence ofappreciable degeneration in the posterior columns.It is evident that the afferent pathways must liewithin the area of degeneration that is common to allthe sections at comparable levels. It therefore lieswithin the degenerated area in the lateral columns.The limits of the common area of degeneration

at the mid-thoracic level are shown most clearlyin Figs. 3, 5, and 6; the anterior limit is shownon the right'side of Fig. 5; the posterior limiton the right side of Fig. 3, and the left side of

Fig. 6. The common area is shown in Fig. 15;it lies on the surface of the cord, opposite thelateral horn.

Fig. 16 shows the common area of degnerationat the upper thoracic level, deduced from anexamination of all 15 cases. This area maintainsthe same position in the cord, as at the mid-thoraciclevel.At the low cervical level the common area of

degeneration is shown most clearly in Figs. 4, 5, 6,and 7. The anterior limit may be determined fromthe right side of Figs. 4 and 5, and the posteriorlimit from the right side of Fig. 4, and the right sideof Fig. 6. Fig. 7 suggests that the commondegenerated area is a fairly narrow band. Thiscommon degenerated area lies on the surface of thecord approximately opposite the posterior angle ofthe anterior horn (Fig. 17). At the high cervicallevel the area of degeneration is fairly constantthroughout the cases. It is in the form of a bandextending from the posterior horn to the anteriorlateral fissure approximately. Figs. 4 and 6 showthat this band is divided into two by an area ofintact fibres, lying a little posterior to the level ofthe lateral dorsal process of the anterior horn.From the 15 cases so far discussed it would not

be possible to determine within which part of thedegenerated area the afferent pathway from thebladder runs. Cases 21, 22, and 28 allow moreaccurate localization to be made. In none of thesecases was there any disturbance of bladder sensation.All three cases show degeneration in the mostposterior zone of the lateral columns on the surfaceof the cord; this degeneration is particularlymarked in Figs. 10 and 11. This degenerated areacorresponds to the more posterior zone of degenera-tion described in Figs. 4 and 6. Therefore theafferent fibres under discussion cannot lie in thisarea, but must run in the more anterior zone ofdegeneration, approximately opposite the lateraldorsal process of the anterior horn (Fig. 18).

Figs. 15 to 18 show the smallest common area ofdegeneration at different levels of the cord in thecases with loss of the sensation underlying thedesire to micturate. This area keeps in approxim-ately the same position on the surface of the cordthroughout the region studied (cervical and upperthoracic); in the thoracic region it is opposite thelateral horn. and in the cervical region opposite thelateral dorsal process of the anterior horn.Case 19 (Fig. 8) is particularly interesting, as pain

from over-distension of the bladder was felt, and,occasionally, the patient stated that he had a desireto micturate. The section of the mid-cervicalregion shows the area of operation on the left sideof the cord. It is possible that the area of degenera-

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Fig. 3. (Case 1). a Th.4. b C7. c: C 1.

Fig. 4. (Case 5). a Th.7. b: C7. c: C2.

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Fig. 5. (Case 6). a: Th.5 and 6. b C7. c Cl.

All figures are photographs of transverse sections of spinal cords (x 4 25) stained to show areas of fibre degenierationt. In Figs. 4, 12, 13,and 14 the sections are stained by the Weigert Pal method.

Figs. 3-8 are from cases with bilateral lesions of the antero-lateral columns involving centripetal pathwaysfrom bladder and some centripetalpathways fronm urethra. In Figs. 3-11, " a " shows the region of operation.

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CENTRIPETAL PATHWAYS WITHIN THE SPINAL CORD FROM THE BLADDER

Figs. 9, 10, and 11 are from caseswith lesions qf the antero-lateralcolumns, wtith partial or noinvolvement of the centripetalpathways.

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Fig. 12. (Case 28). a: Th.5. b: C3.

A.'

Fig. 13. (Case 29). a: Th.2. b C7. c C4.

Fig. 14. (Case 30). a: Th.4. b: C7. c: C4.

Figs. 12, 13, anid 14 are from cases with lesions not involving the centripetal pathways.

PLATE IV

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tion on the left side does not extend as far posteriorlyas the total extent of the area within which theafferent pathway lies. It is possible that a few fibresin this area were not divided. This suggestion issupported by the Gros' silver preparation of thespinal cord just rostral to the operation area.Sections prepared by this method to demonstrateaxis cylinders show more precisely the limits ofdestruction of fibres. From these silver sections itcan be seen that the area of destruction does notextend as far posteriorly as the limit of the commonpathway.Group 1(b).-This group consists of cases in which

the pathways conducting the sensation of a fullbladder and pain from the bladder are bilaterallyintact: 28, 29, and 30. All these cases wereexamined histologically.

Photographs of representative sections are shownon Plate IV. This group consists of the cases thatform the control. They provide further evidenceof the region where these afferent fibres do not run.In Fig. 12 there is almost complete degeneration ofthe posterior half of the lateral columns in the highcervical level. There is no degeneration in thiscase in the area of the lateral columns, or on thesurface of the cord opposite the lateral dorsalprocess of the anterior horn, where it has beenshown that the afferent pathway lies. In Fig. 13there is almost complete degeneration in the funiculigraciles, a very few anterior fibres being spared.In Fig. 14 at the high cervical level the funiculigraciles are degenerated, except for a few posteriorfibres ; the mid-zone of the funiculi cuneati are alsodegenerated. No bladder dysfunction of any kindoccurred in these cases, confirming that no afferentpathway from the bladder runs in the posteriorcolumns.

Group 1(c).-This group consists of cases in whichthe pathways conducting the sensation of a fullbladder and pain from the bladder are unilaterallydivided: 20, 21, 22, 23, 24, 25, and 26.

Cases 20, 21, and 22 were examined histologically.Photographs of representative sections are shownon Plate III. In Case 20 (Fig. 9), the operation wasunilateral; although the degeneration includes thatcommon area demonstrated in Group l(a), thesensations of needing to micturate and of pain werenormal. In Case 21 (Fig. 10), the area destroyed atoperation is very anterior; in Case 22 (Fig. 1) it isvery posterior. In these two cases the pathway underdiscussion may have been sectioned on one side, buton the other side it was definitely intact. In Fig. 10the degeneration on the left side does not involve theregion under discussion; in Fig. lIthe degeneratedarea on the right side might include this afferent

pathway, but on the left side the pathway isdefinitely not involved. Thus, as far as this afferentpathway is concerned, these two cases may betreated as unilateral cases. They confirm thefindings from Case 20, which shows that when theafferent pathway is divided unilaterally the subjectstill remains aware of the state of distension of hisbladder and has the sensation of needing to micturateand the pain of over-distension.

Group 2(a).-This group consists of cases in whichthe pathways conducting the sensations of pain andtemperature from the urethra are bilaterally divided:1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, and 19.Cases 1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, and 19

were examined histologically. Photographs ofsections from representative cases are shown inPlates I and I1. These are the same cases as havebeen discussed in Group 1(a), without Case 8. Thesmallest common area of degeneration was deter-mined in the section dealing with Group 1(a). It isthus evident that the pathway conducting thesensations of pain and temperature from the bladderand the urethra lies within the same area ofdegeneration as the pathways conducting the sensa-tion of a full bladder (Figs. 15 to 18).

Group 2(b).-This group consists of cases in whichthe pathways conducting the sensations of pain andtemperature from the urethra are unilaterallydivided: 8, 17, 20, 21, 23, and 24.

Cases 8, 20, and 21 were examined histologically.Photographs of representative sections of Cases 20and 21 are shown in Plate II1. These cases havealready been considered under Group 1(c). It isseen that the pathway conducting impulses sub-serving pain and temperature from the urethra runsin the same region as that conducting impulsessubserving the sensation of a full bladder and painfrom the bladder.

DiscussionSeventeen patients with bilateral lesions of the

spino-thalamic tract had lost the normal sensationunderlying the desire to micturate, and the sensationsof pain and temperature from the bladder andurethra. The pathway in the cord conducting theimpulses giving rise to these sensations lies on thesurface of the cord, approximately opposite thedorsal lateral process of the anterior horn. It liesin the same region of the cord as that conveyingimpulses interpreted as pain, warmth, and cold fromthe sacral segments of the body.A control group of cases without lesions of the

spino-thalamic tract has been given; these caseshad degeneration of spinal tracts, with normalbladder and urethral sensation. A case of subacute



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P. W. NATHAN AND MARION C. SMITHcombined degeneration of the cord (Case 29), and acase of Friedreich's ataxia (Case 30) show degenera-tion of afferent pathways with no disturbance of thesensations that concern us here. The inclusion of acase of amyotrophic lateral sclerosis (Case 28), amotor and not a sensory disorder, is justified onsimilar grounds: the lesions in the spinal cordserve to show where the tracts do not run. Thesefew cases were included because clear histologicalspecimens were available. Many other cases havebeen seen, with similar lesions not involving thispathway. Such patients had had no abnormalityor lack of sensation from the bladder.Thus the evidence presented shows that the

centripetal tract in man lies in a region of the cordsimilar to where it lies in the cat. In man itsposition is somewhat more lateral, for it lies withinthe most lateral region of the cord, about midwaybetween the anterior and posterior horns (Figs. 15

Fig. 15.-Mid-thoracic region.

to 18). It should be possible to narrow down theregion occupied by this tract still further, as moreevidence is collected.The only other evidence known to us is that of the

case reported by McMichael. In his specimen thetract could not be identified in the cervical region,and was not clear in the thoracic region. In thelumbar region-the region that could not beinvestigated in our series of cordotomies-" WeigertPal sections showed a bilaterally symmetrical zoneof degeneration immediately anterior to the posteriorcornua lying superficially in the lateral columns ".This region is similar to that in which the pathwayhas been located in the present investigation in thethoracic and cervical regions; but in the casespresented here, at the higher levels, it is more anteriorand more lateral ; for there is an area free fromdegeneration immediately anterior to the posteriorcornua. McMichael's case is particularly im-

Fig. 16.-Upper thoracic region.

Fig. 17.-Lower cervical region. Fig. 18.-Upper cervical region.

Figs. 15-18.-Drawings of transverse section7s of the spinal cord. The area containing the centripetalpathway.from the bladder andthespin-thalamic pathway from the urethra is shaded.

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CENTRIPETAL PATHWA YS WI7HIN THE SPINAL CORD FROM THE BLADDER 279

portant, as the patient had no somatic sensory loss,for it shows that the part of the lateral columnconveying the centripetal path from the bladdercan be divided, without there being a simultaneousdivision of the somatic centripetal pathway inthe spino-thalamic tract.Most patients having a unilateral lesion of the

spino-thalamic tract notice no change in bladderfunction, and retain the normal sensation of a fullbladder and desire to micturate. In all, 12 cases ofunilateral cordotomy have been studied; seven arenot included in this series, as they added nothing tothose described here. In five of them (Cases 20,23, 25, 26, and 27) for some time the sensation givingrise to the desire to micturate was experiencedunilaterally; in the others no abnormality wasnoted. Direct questioning on the laterality of thissensation was not used, because the possibilityof the sensation being unilateral had not beenthought of until Case 23 was seen. Before thisinvestigation was begun, three cases of throm-bosis of the posterior inferior cerebellar artery hadbeen studied. These patients were not questionedabout the desire to micturate; none of themspontaneously made any comments on it, or onurethral sensation. Towards the end of thisinvestigation a further case (Case 24) was en-countered. This patient in reply to questioningstated that he had the normal sensations under-lying the desire to micturate, and that he felt hisurine passing in the normal manner. He was theninvestigated in accordance with the scheme em-ployed for the cases of this series. The patient thennoticed that when he was catheterized, he felt thepassage of the catheter only on the left, which wasthe side of the body having normal sensation. Ashis bladder was filled, he was then surprised to findthat he experienced the desire to micturate only onthe left. From the experience of this case, one isinclined to wonder whether the other cases ofposterior inferior cerebellar artery thrombosis mightnot have had this sensation unilaterally had theirattention been directed to their sensations; duringcystometrography there is ample time for observingsensations while the bladder is being slowly filled.Two of the patients with unilateral cordotomy(Cases 26 and 27) experienced this sensationunilaterally only when the desire to micturatebecame urgent enough to force itself on theirattention.To account for the discrepancy in the evidence

of these six patients, who felt the sensation under-lying the desire to micturate unilaterally, and thatof other patients with a unilateral lesion feeling thesensation centrally and not unilaterally, one mayconsider two possibilities. It could be that a vague

and poorly localized sensation, such as that under-lying the desire to micturate, is felt centrally andbilaterally, whatever the anatomical pathwaysubserving it; for it could be that for a sensationthat has for years been central and bilateral apattern of perception has become so fixed that itover-rides the perception of an innovation in thesensation. Or it might be that, in some cases, thispathway from one side of the bladder runs up bothsides of the cord, while in others it runs up theopposite side of the cord only.From unilateral cases, it was learnt that the

pathway conducting impulses subserving the sensa-tion of pain from the lower ends of the ureters, fromthe walls of the bladder, from the urethra, andthermal sensation from the urethra, also runs in thespino-thalamic tract, and in the same region as thatconducting the sensation underlying the desire tomicturate.

Patients in whom the pathway in the spino-thalamic tract has been divided, may retain thesensation that micturition is impending, that it isprogressing, and that it has ceased. These sensa-tions are doubtless due to impulses arising in theurethral mucosa and in the sphincter urethraemembranaceae and the large group of perinealmuscles that act synergically with the sphincter. Suchimpulses doubtless travel via the posterior columns.

It remains to answer the question: why do notall patients, after bilateral spino-thalamic cordotomy,have urethral sensation, giving them knowledgethat micturition is starting, progressing, and stopping.

Immediately after division of both spino-thalamictracts patients may have no sensation from bladderor urethra. This occurs more commonly in womenthan in men, and is likely to be due to the fact thatwomen have shorter urethras than men, with lesslength of mucosa. This condition may last amonth or more, and patients who die in thisperiod have therefore regained no urethral sensation.Those living past this stage tend to feel more. Theremoval, by division of the spino-thalamic tracts, ofall sensation from the bladder, and the greater partof sensation from the urethra-for the sensations ofpain and warmth and cold are the predominanturethral sensations-demands from the patients are-orientation to the sensations perceived. Similarlyin the sphere of somatic sensation, many patientslose the ability to tell sharp from blunt; but othersdo not. Also, the feeling of wetness is difficult toperceive after spino-thalamic division, doubtlessdue to the removal of thermal sense; but somepatients learn to know when something is wet, whileothers do not-both having the same sensoryapparatus. After cordotomy a new sensory patternfrom the urethra is presented to consciousness;



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not all patients become equally adept in inter-preting it. Its interpretation depends on the abilityto carry out minute observations on one's ownsensations. Further, the patients' ability to explainwhat they feel enters into the question of whatsensation is regained; probably patients oftenexperience sensations of greater complication thanthey are able to describe.As has been noted in the histories of these patients,

there is a vagfie sensation related to distension or risein pressure in the bladder, which we have called,non-committally, a substitute sensation. We donot propose discussing this sensation further here;work is continuing on the origin of the sensation, andthe pathway by which the impulses subserving itreach the cerebrum. It is sufficient to point out thatwherever these impulses arise, they do not travelin the spino-thalamic tract.

It remains to discuss Case 19, the patient who lostthe normal desire to micturate, and who was found,within 24 hours of the operation that cut off thesensation of pain from the rest of his body belowthe fourth thoracic segment, to be suffering fromgreat pain due to distension of the bladder. Althoughthere was good recovery of urethral sensation,urethral pain was not regained; and so the pain ofdistension of the bladder cannot be attributed tourethral sensation. As has been mentioned whenconsidering the histological evidence, it is probablethat a few fibres, at least on one side, lyingposteriorly, escaped cutting at operation. One isunwilling to draw too definite a conclusion from onecase, with regard to a possible separation of path-ways subserving pain and pathways subserving thedesire to micturate. As further evidence is col-lected, it may become possible to draw further con-clusions about the detailed topography of these tracts.

Before finishing this discussion on pathways ofconduction of impulses that are interpreted assensation, it is of importance to remember that thesensation of having a full bladder that needs to beemptied, can, like all sensations, be evoked bypsychic factors. This was shown clearly by one ofour patients, the subject of Case 9, who, although shehad no sensation from her distended bladder,experienced the sensation of needing to micturate,whenever she saw or heard the bed-pans being takenround the ward.

SummaryThe location within the spinal cord of man of the

following afferent pathways has been determined:

(a) that subserving the sensation that the bladder isfull, giving rise to the desire to micturate; (b) thatsubserving the sensations of pain from the bladder,urethra, and lower end of the ureter, and sensation oftemperature from the urethra; (c) that subservingtouch and pressure or tension from the urethra.The pathways considered under the headings (a)and (b) lie within the spino-thalamic tract on thesurface of the cord opposite the dorsal lateral processof the anterior horn. The pathways consideredunder (c) lie within the posterior columns.

We wish to express our gratitude to Mr. WylieMcKissock for his whole-hearted cooperation; heoperated on the majority of these patients, and, whilerelieving their pain, maintained a scientific attitude,which greatly aided the investigation, of which thispaper is the first report.We are grateful to the many surgeons and pathologists

who have helped us in this work; and particularly toMr. O'Connell, Professor Norman Dott, Mr. DicksonWright, Mr. Norman Matheson, Mr. E. A. Turner,Mr. Malcolm Donaldson, Dr. J. G. Greenfield, Dr.W. Blackwood, Dr. W. G. C. Mair, and ProfessorW. D. Newcomb. We wish to thank Mr. P. B. Ryanfor carrying out a number of the cystoscopies. Weare also grateful to Dr. E. A. Carmichael, who helpedus by providing the facilities for this investigation andby his interest and criticism. Our thanks are due to theMedical Committee of the National Hospital for NervousDiseases for allowing us to use their case records.We wish also to thank Mr. F. J. F. Barrington and

the Editor of Brain for permission to reproduce Fig. 1.To our technical assistants, Mrs. J. A. Mills and Miss

Kathleen Harrison, we wish to express our gratitude fortheir careful and painstaking work; and we also wishto thank Mr. J. A. Mills for. giving us the benefit of hisexperience of histological techniques and photography.

Patients 6, 11, 13, 19, 24, 25, and 27 were in the NationalHospital; their case numbers were respectively 18299,23011, 16162, 12166, 30790, 26668, and 16148.

REFERENCESBarrington, F. J. F. (1925). Quart. J. exp. Physiol., 15, 81.

(1933). Brain, 56, 126.Bing, R., and Haymaker, W. (1939). "Textbook ofNervous Disease." St. Louis.

Frankl-Hochwart, L. von, and Zuckerkandl, 0. (1906).Die nervosen Erkrankungen der Harnblase, 2nd ed.Vienna.

Guttmann, L., and Whitteridge, D. (1947). Brain, 70,361.McMichael, J. (1945). Ibid., 68, 162.Muller, L. R. (1919). Dtsch. Arch. klin. Med., 128, 81.Smith, M. C. (1951). Journal of Neurology, Neuro-

surgerty, and Psychiatry, 14, 222.

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