CONTROL OF SOMATIC PAIN*

WILLIAM BATES, M.D.

PHILADELPHIA,

T HE relief of pain has always been one of the chief functions of a doctor. Pain of viscera1 origin has been the

reason for the existence of a surgeon, How- ever, the differentiation between viscera1 and somatic pain has not aIways been an easy one to make.

The types of somatic pain to which we have devoted most of our attention are those neuralgias which are segmenta in distribution and which are associated with tenderness. Pain due to segmenta neuraI- gias, by virtue of its variation in Iocation, character and intensity, may simuIate the pain of aImost any form of viscera1 disease.

EvaIuation of the pain in these patients has been made more definite by various factors: (I) The finding of tender points at the emergence of the posterior, IateraI or anterior cutaneous branches of the inter- Costa1 nerves; (2) the estabIishment of tenderness in segments corresponding to definite dermatomes which are associated with the pain; (3) the fact that segmenta tenderness is rareIy initiated by the pain of viscera1 stimuh, unIess a widespread peri- tonitis is present; (4) the finding of reduced skin surface temperature which is often associated with the pain and tenderness, and (3) foIIowing nerve bIock, pain and associated tenderness shouId disappear simuItaneousIy.

In many series of operations, the faiIures reported are chiefly in patients whose cardina1 compIaint was pain. This I beIieve is not due to incompIete or incompetent surgery but to faiIure in diagnosing the source of the pain.

In 1926, when a former member of the Academy of Surgery, the Iate Dr. J. Berton Carnett, first wrote about intercosta1 neuraIgia of the abdomina1 waI1, he stressed this same fact.

PENNSYLVANIA

His work met with differences of opinion, but his basic reasoning has been sub- stantiated many times. It is very true that to foIIow his teachings of that time might have Ied to some serious mistakes. On the other hand, it wouId have prevented many useIess operations. In his teachings, he advocated differentiating viscera1 from somatic pain. He d escribed his tests to accompIish this. He gave a series of causes for the existence of somatic or as he caIIed it, intercosta1 pain, and IastIy, he attempted to outIine methods of treatment for this condition.

This Iatter fact was unfortunate and was forced upon him and his staff rather pre- matureIy. Having brought the picture of surface pain to the attention of practi- tioners they demanded some method of treatment. Among the recommendations for treatment was, of course, the cIassic one of “eIiminate the cause.” This we tried to do, but in many cases we found that the pain persisted Iong after the apparent cause had been removed. Something more was needed in those patients whose toxic foci were eIiminated and postura1 defects corrected, with no reIief of their pain.

At this stage of deveIopment of our cIinica1 probIem, an attempt was made in cases of IocaI pain and tenderness to inject with novocain. As one might expect, most of the cases got onIy temporary reIief. However, quite a few got proIonged reIief encouraging us to repeat the injections. When proIonged reIief was obtained by such a simpIe procedure, we were of the opinion that the basic cause or causes were probabIy corrected in conjunction with the infiItration.

About rg3 I, one of the men on Dr. Carnett’s service at the Graduate Hospital, Dr. B. D. Judovich, did some work on the

* Annual Oration for 1941. Read before the Academy of Surgery, November, 1941, Philadelphia.

83

84 American Journal of Surgery Bates-Somatic Pain

pitcher plant-Sarracenia purpurea. He prepared an aqueous soIution derived from this pIant, and observed that it was of value in reheving pain of neuralgic origin. It was beheved at that time that its proper- ties were due to the presence of amines. It was noted that the preparation had an action upon sensory nerves, reheving neu- ralgic pain without producing changes in skin sensation and having no effect upon motor nerves.

Dr. Carnett suggested that Dr. Judovich be aIlowed to work in what we caIIed the Intercostal Neuralgia CIinic. Heretofore we had been trying to determine the cause of the pain, and treat by means of elimi- nating foca1 infections, correction of pos- tural defects, giving GoIdthwaite exercises and the occasiona injection of novocain solution in some of the more persistent cases of localized pain and tenderness.

From then on, even though we did not know the actua1 active principle of the soIution we caIIed Sarapin, it was adminis- tered to numerous patients suffering with pain of somatic origin.

ControIs of novocain, sahne and water were used, and the results recorded. The key numbers of these various ampoules were changed severa times, and on anaIysis in each series, it was found that Sarapin produced prolonged reIief in contrast to fleeting or negative results with the other soIutions. In a number of instances, pa- tients who had been injected with novocain with onIy a short period of reIief of pain, obtained prolonged rehef by a subsequent injection pitcher-piant distillate.

Toxicity tests reveaIed that it was harm- less. It caused no tissue coaguIation nor sclerosis. This action was unusua1 and diffrcuIt to substantiate. We were treating a subjective symptom, and Iaboratory animaIs gave no actua1 data except in reference to toxicity. Routine pharmaco- Iogic tests in three different Iaboratories threw no Iight upon the probIem.

FoIIowing its injection of periphera1 nerves, there were no cases of motor weak- ness, nor Ioss of touch, pressure, pinprick

nor temperature sensibiIity. In some cases, one infiItration of the distiIIate was suff~- cient to provide permanent reIief of pain, even though of Iong duration. The psychic factor of reIief in this type of pain has IargeIy been ruled out by estabIishing the presence of tenderness in the dermatomes of the painfu1 segments.

In intercosta1 neuraIgia, paravertebral injection of the nerve trunks invoIved, resuIts in an immediate intensihcation of the pain, folIowed during the next thirty minutes, by a graduaI contraction of the hyperaIgesic area in the dermatome sup- pIied by the nerve. In a large number of cases it is followed by complete reIief of neuralgia.

Because of the segmenta overIap, the effect of the distiIIate upon sensations other than neuraIgia cannot be evaluated.

If, in a case of sciatic neuraIgia, the region of the sacrosciatic foramen is infiItrated with the pitcher-plant distiIIate, there is relief of the neuralgic pain as we11 as of tenderness along the nerve trunk. This is simiIar to resuIts from infiItration of novo- Cain, but in contrast to the action of novocain there is no numbness, no Ioss of sensibiIity and no motor weakness. Reflexes remain unchanged.

In 1939, investigation was made by Dr. Winifred Stewart and Dr. Joseph Hughes, using the cathode ray osciIIograph to determine the action of the pitcher-pIant distiIIate upon the nerve impuIse.

Their studies indicated that the somatic c wave impuIse, which is supposedIy trans- mitted by way of the small unmyeIinated fibers, was depressed in each instance. A report of these findings was made in 1940 by Stewart, Hughes and Judovich in which they stated: “The abiIity of pitcher pIant distiIIate to aboIish neuraIgia pain which, like fascia1 pain, is aching, poorly IocaIized, and frequentIy associated with nausea and sweating, and at the same time, to Ieave pinprick as we11 as other forms of sensi- bihty unaffected, Ied us to inquire further into its physiotogica1 action, and to at- tempt to determine its active principle.

NEW SERIES VOL. LIX, No. I Bates-Somatic Pain American Journal of Surgery 85

“The effect of pitcher pIant distiilate on the action potentiaIs of the saphenous nerve of the cat was observed. The nerve was mounted in a nerve chamber in a gas mixture of five per cent carbon dioxide and ninety-five per cent oxygen. The tempera- ture was maintained at 37.5O to 38”~. The nerve was so mounted that it couId be bathed in the solution to be studied. The pitcher pIant distiIIate was adjusted to a pH. of 7.4. The action potentiaIs were recorded on a cathode ray osciIIograph.

“After five minutes immersion in pitcher pIant distiIIate, the maxima1 A spike was somewhat reduced whiIe the c fiber poten- tiaIs were obIiterated.”

For the first time it appeared that we had some definite objective proof that the soIution we had been using shouId reIieve pain. It became vitaIIy important to us to know the chemiczi1 constituents of this soIution. The first report we received on the anaIysis showed that the crystalline compound which was isoIated was ammo- nium chIoride. Experiments in the Iabora- tory were carried out with distiIIate of pitcher-plant soIution of known ammonium chIoride. AI1 three soIutions gave the same result. CIinicaIIy, injections of Sarapin and of a soIution of ammonium produced the same proIonged reIief.

On checking the chemica1 process by which the distiIIate was obtained, Judovich found that the end resuIt shouId have been a suIfate and not a chIoride. Accordingly, further experiments were carried out with a soIution of known ammonium sulfate. Both cIinicaIIy and experimentaIIy the resuIts were paraIIe1 to those found with the SOIU- tion of ammonium chIoride. From this it was readily deducted, that, as the ammo- nium radical was onIy constant, that it was the active principIe responsibIe for our resuIts.

These observations on actua1 patients led us to beIieve that neuraIgic pain and pin- prick are mediated by separate fiber groups. CIinicaIIy, however, we have been unabIe to reIieve pain of viscera1 or

sympathetic origin by the injection of ammonium saIts.

In two instances the first and second lumbar sympathetic gangIia were injected in a patient with vascuIar occIusion of the Iower extremity. There was no change in the skin surface temperature of the leg folIowing infiItration of these points with ammonium saIts. The needIes were Ieft in place and at the end of twenty minutes z per cent novocain soIution was injected. Within two minutes a definite rise in skin temperature was obtained. AI1 patients benefitted by these injections were cases of pain of somatic origin associated with tenderness.

On occasion, the infiItration of the pitcher-pIant distiIIate and the ammonium saIts have been of vaIue in differential diagnosis; neither of these substances has any effect upon vascuIar pain or pain of viscera1 origin.

Just what the difference is in the un- myeIinated c fiber of periphera1 distribu- tion which responds to these injections, and the unmyeIinated c fibers of the sym- pathetic nerves and their gangIia which do not respond to these injections, we do not know. Experiments are being conducted by Dr. Stewart and Dr. Hughes upon sympathetic fibers to determine the effect of ammonium saIts upon the nerve impuIse in this type of tissue.

This has no doubt been a proIonged expIanation of a simpIe procedure, but the cIinica1 resuIts have been so satisfactory to some of us, that the confirmation of our ten years of cIinica1 observations by Iaboratory proof, make it seem worth whiIe to render this report. . Our work in attempting to contro1 pain is

by no means complete, as the same soIu- tions are now being tested intraspinaIIy for intractabIe pain. To date the resuIts in certain cases have been most promising, but more data must be coIIected before definite concIusions can be made.

I am not recommending regiona infiltra- tion as a cure-a11 for aches and pains, but without it, we wouId have been unabIe to

86 Bates-Somatic Pain

relieve many patients of their persistent most effkacious method of treatment for

pain. somatic pain. It is also of vaIue in diagnosis.

4. The use of the pitcher-pIant extract, in many patients, has afforded proIonged

reIief as compared with procaine. 5. Injection of soIutions of ammonium

inorganic saIts both Iocally and intra- spinally have given promising resuIts. The

advantages are nontoxicity and absence of

tissue damage.

SUMMARY

I. SegmentaI neuralgias may often simu-

late the symptoms of visceral disease.

These very often account for pain which

persists folIowing surgery.

2. Various factors are mentioned which

are important in the differentiation of pain

of viscera1 and pain of somatic origin.

3. RegionaI infiItration appears to be the

6. A rCsume is given of the experimental and cIinica1 value of both the pitcher-pIant and ammonium saIts.

OCCASIONALLY a patient wiII receive an overdose of a local anesthetic

agent and have convukions or convuIsions may deveIop under genera1

anesthesia. If the convuIsions are severe, death wiI1 ensue unIess artificia1 respiration is carried out to ventiIate the patient enough to support Iife. The use of an anticonvuIsant drug may be necessary to accompIish this. From “CIinicaI Anesthesia” by John S. Lundy (W. B. Saunders Company).