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Diagnosis of Leprosy: Part II. Cardinal signsSalvatore Noto and Pieter A M SchreuderLeprosy Mailing List May !"#"

Diagnosis of leprosy

Salvatore Noto and Pieter A M Schreuder

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Part II. Cardinal signs

The 1stcardinal sign: skin patch with loss of sensation

Sensory loss in macules or plaques is diagnostic of leprosy (Slide 2). There are very fe!

if any! s"in diseases that present anaesthetic lesions. #nly hen there are very thic"

squamae there may $e a %pseudo loss& to a very fine touch' indeed never anaesthesia.

Macules and plaques in leprosy may sho several other typical a$normalities. The colour

can $e hypopigmented! hyperpigmented! erythematous or coppercoloured. Theteture

of the surface may $e dry and rough for loss of seat in some forms of the disease! or

shiny and smooth in others. There may $e loss of hair groth. Some macules may sho

typical streaming on one side of their margins and satellite lesions. The lesions may

$ecome acutely infiltrated! sollen and erythematous.

Some leprologists consider %characteristic& s"in lesions an additional cardinal sign.

%*haracteristic& has $een eplained as+ hypopigmentation in dar" s"in in tu$erculoid and

indeterminate leprosy or diffuse infiltration! macules! papules and nodules in lepromatous

leprosy. ,oever! in our point of vie! none of these a$normalities confirms the diagnosis

of leprosy unless! there is either a loss of sensitivity! an enlarged nerve or a positive slit

s"in smear.

-or all purposes in leprosy loss of sensation in a s"in lesion is diagnostic of the disease

(Slides ! /). The loss of cutaneous sensation is often partial' it may $e to light touch

(anaesthesia)! to pain (analgesia) or to temperature discrimination (hot and cold).

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Testing for loss of sensation

This is a relatively simple test that confirms diagnosis of leprosy in many cases. 0uietnessin the environment or in the room here it is performed is important. 1oth the patient and

the eaminer must $e positioned comforta$ly hile eamining.

The simplest and quic"est ay to test for anaesthesia is to use the tip of your finger to

touch the patient. sing the pulp of your little or ring finger! touch the patient very gently.

3f you can feel it! he should too (,astings 456).

More commonly a fine! pointed isp of cotton (Slide 7) ool is used to touch the part to $etested. -irst eplain to the patient hat you ill $e doing. Then demonstrate hile he

atches and points carefully to the eact spot touched. 8hen he comprehends fully! then

continue testing various sites in and outside the lesions $ut! ith the patient9s eyes

covered (Slide :). Touch only! do not $rush across the s"in. 3na$ility to identify the point

stimulated at all! denotes loss of sensation to the stimulus used. 3f he feels it $ut he

cannot point to the eact spot! it is called misreference! and it is the earliest sign of

hypoesthesia (,astings 456). The patient ith closed eyes can either point ith one

finger to the eact spot here the cotton ool touched the s"in or the patient can confirm

the eact place ver$ally hen he feels the touch. Test the relia$ility of the patient $y

as"ing here he feels hen not touching the s"in at all.

Alternatively heat sensation is tested ith to test tu$es! one containing hot ater and the

other cold ater (;aal"ar S < 2==2).

*otton ool may $e too delicate for the thic"ened s"in of palms and soles. Monofilaments

or nylon $ristles could $e used to test for sensory loss in lesions on palms and soles. The

Semmes 8einstein monofilament test is noadays recommended for assessing peripheral

nerve impairment. Sensory testing (ST) ill $e discussed in more detail in the part a$out

%>eactions and nerve damage&.

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Warnings:

4.?oss of cutaneous sensation means that the sensation! in particular the touch! in the lesion

is diminished in comparison ith the surrounding s"in. ?oss of cutaneous sensation may

also $e to pain and to temperature.

2.

Sensory changes on face may $e less evident than in other areas of the $ody $ecause of

the rich nerve supply of the face.

7.

Toards the lepromatous side of the spectrum! $orderline lepromatous and lepromatous

leprosy! in early cases often no loss of sensation is found. 3n advanced lepromatous

cases there may $e etensive loss of sensation and! $ilateral anaesthesia of the glove

andstoc"ing type.

:.

3n the @indeterminate@ form of leprosy! loss of sensation cannot $e detected' $ut

sometimes loss of autonomic nerve function can $e found.

.

Pain sensation is tested $y pinpric" ($e careful not to damage the s"in) and temperature

$y touching the s"in ith test tu$es containing hot and cold ater.

The sweat and histamine tests

To other tests may $e useful in diagnosing leprosy and are used $y some leprologists+

4.

Seat test+ seating is dependent upon the integrity of parasympathetic nerve fi$res. 3f a

hypopigmented patch is due to leprosy the response of the seat glands to eercise or to

a cholinergic drug ill $e diminished (Slide 6) 1ryceson A! PfaltBgraff >oy C (455=)D'.

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2.

,istamine test+ the heal and flare response to histamine is the end product of a local

refle hich depends upon the integrity of sympathetic nerve fi$res. 3f a hypopigmented

patch is due to leprosy the response of the s"in to histamine ill $e diminished (Slide 4=)

1ryceson A! PfaltBgraff >oy C (455=)' Menicucci ?. et al.' >odrigueB

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The 2nd cardinal sign of leprosy: enlarged peripheral nerve

An enlarged peripheral nerve represents the 2nd cardinal sign of leprosy (Slide 2).Cnlarged peripheral nerves are very rarely found ecept in leprosy. #ther conditions hich

could present enlarged peripheral nerves are+ primary amyloidosis and some hereditary

peripheral neuropathies (li"e the neuropathy of *harcotMarieTooth). These are all very

uncommon. 3n a leprosy endemic area! the finding of enlarged peripheral nerves is an

important element to esta$lish the diagnosis.

The palpation of the nerves at the %sites of predilection& is performed during the physical

eamination of the patient. Palpation is performed gently using the pulp of the fingers! not

the finger tip or finger nail. 8atch the person9s face to ma"e sure you do not cause him

unnecessary pain hen you touch the nerve. Cvaluate the tenderness (spontaneous or

hen palpating)! consistency (soft! hard! irregular) and siBe (enlarged! normal! small) of

the nerve' hoever! only the siBe is important for the diagnosis of leprosy (Slide 7).

Tenderness hen palpating the nerve or spontaneous nerve pain are signs of a reaction.

Additionally! signs and symptoms of peripheral nerve sensory! motor and autonomic

involvement may $e present.

3t is essential to "no the normal limits $y constant practice in palpating nerves. Euring an

eamination one should alays compare nerves on the opposite site of the $ody.

All peripheral nerves may $e enlarged in leprosy. *utaneous $ranches associated ith a

s"in lesion may $e enlarged as ell (Slides 7:7). The to most commonly affected are

the ulnar nerve and! in the second place! the lateral popliteal (also called common

peroneal) nerve. 3n the folloing paragraphs! ho to locate and palpate the peripheralnerves of predilection in leprosy ill $e illustrated. They ill $e descri$ed systematically

starting from the head! then those of the upper lim$s and finally those of the loer lim$s.

Supraorbital nerve

An enlarged supraor$ital nerve is palpa$le as it passes upards out of the or$it (Slide 6).

To palpate it run your inde finger across the forehead from the midline laterally. A $ranch

of this nerve can $e seen is Slide 5.

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Great auricular nerve

The great auricular nerve can $e seen in the nec" emerging from the posterior $order of

the sternocleidomastoid muscle. The patient turns hisFher head to one side! thus this

muscle is stretched. The great auricular nerve courses anteriorly and superiorly across

the muscle toards the earlo$e (Slides 4=47).

Ulnar nerve

The forearm of the patient is $ent at 5=G44=G over the arm. The eaminer uses his left

hand to palpate the right ulnar nerve and his left hand to palpate the right ulnar nerve. The

nerve can $e palpated first at the el$o in the olecranon groove! $eteen the olecranon

and the medial epicondyle of the humerus. Then it can $e felt and evaluated immediately

a$ove the groove (Slides 4 4/). 3n comparing left and right ulnar nerves it is useful to

as" the patient to put his hands on the eaminer9s shoulders' in this case the $ending is

a$out 47G (1en Naafs! personal communication). Alternatively the patient may hold his

on hands in front of him. 1ranch of the ulnar nerve can $e palpated on the dorsum of the

hand as it curls round the th metacarpal $one. This is a useful confirmatory sign in

someone ith vague neuritis symptoms in the fingers and no other signs of leprosy (Hrace

8arren personal communication).

adial cutaneous nerve

The radial cutaneous nerve is palpated at the rist. 3t can $e rolled under the tips of the

eaminer9s fingers as it crosses the lateral $order of the radius Iust proimal to the rist

and courses onto the dorsum of the hand (Slides 4J 24). The radial cutaneous nerve can

also $e palpated as it rolls round the 2nd metacarpal $one. No other clinical or la$oratory

test has the same high sensitivity and specificity (van ,ees *.! Naafs 1.! 2==5).

!edian nerve

The median nerve is felt in front of the rist hen the rist Ioint is semifleed! proimal to

the fleor retinaculum. 3t is often easier to see than to palpate due to the presence (if

present) of the tendon of the palmaris longus muscle. (Slides 22 2:).

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"ateral popliteal nerve #$ommon peroneal nerve%

The lateral popliteal nerve can $e palpated! ith the "nee Ioint semifleed! in the popliteal

fossa! Iust medial to the $iceps femoris tendon (Slides 2 2J) and! as it passes round the

nec" of the fi$ula. Alternatively it can $e felt ith the patient and the eaminer! one seated

in front of the other.

Superficial peroneal nerve

The superficial peroneal nerve (also called dorsalis pedis) can $e easily palpated on the

dorsum of the foot (Slides 267=).

&osterior tibial nerve

The posterior ti$ial nerve is palpa$le as it passes posteriorly and inferiorly to the medial

malleolus and supplies the sole of the foot (Slide 72). 3t is difficult to palpate due to

tendons and $lood vessels hich also pass at the spot.

Sural nerve

The sural nerve can $e palpated along the midline of the $ac" of the loer leg. The mid to

loer part of the leg! here calf muscles Ioin to the Achilles9 tendon. The sural nerve can

also $e palpated as it runs don $ehind and under the lateral malleolus and along the

lateral side of the foot.

Warnings

3t is not uncommon in a leprosy endemic area to find people ith an enlarged great

auricular nerve or radial cutaneous nerve ithout any other clinical sign of leprosy

(including nerve function impairment) or positive $acteriology. Such patients are not put

on treatment $ut o$served and told to come $ac" if anything changes or if the patients

develop s"in lesions. The enlargement of these to nerves has no direct clinical

relevance.

3n early cases of leprosy nerve enlargement may not $e very great! the nerve may not $e

tender and hard palpation may not even cause discomfort. The hardness is the clue in this

casesK Thin hard nerve may still $e palpa$le years later and confirm a self healed caseyears after the active disease (Hrace 8arren! personal communication).

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The 'rd cardinal sign of leprosy: positive slit(skin smear

?eprosy is the only disease in hich there can $e a massive invasion of the dermis or

nasal mucosa ith acidfast $acilli (A-1). 3n some forms of the disease $acilli are

demonstrated in slits"in smears or in nasal mucus or scrapings.

?eprosy $acilli are etremely scanty in lesions of some forms of leprosy! $ut are present in

enormous num$ers in lesions of other forms of the same disease. #ne gram of s"in tissue

in lepromatous leprosy may contain as many as J=== million leprosy $acilli (;aal"ar S idley and

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3n endemic areas s"in smears should not only $e used to prove that the patient is suffering

from leprosy! $ut also to eclude leprosy in patients ith multiple s"in lesions.

S"in smears should $e ta"en from all patients suspected of suffering from leprosy.

Smears are ta"en from suspected s"in lesions and particularly from the most active

loo"ing edge of the lesion and especially in lepromatous leprosy from sites ith a high

pro$a$ility of demonstrating A-1. Such sites ith the highest pro$a$ility of demonstrating

A-1 are the earlo$es! forehead! chin! etensor surface of the forearms! dorsal surface of

the fingers! $uttoc"s and etensor surface of "nees.

The slit and scrape method

A fold of s"in is pic"ed up $eteen finger and thum$ and is squeeBed to prevent $lood flo

(Slide 7). A small incision! J6 mm length and 42 mm deep! is made into the dermis ith

a scalpel $lade (Slide :). The $lade is then turned through 5= degrees and used to scrape

the cut surface of the tissue (Slide ). *are has to $e ta"en to avoid $lood miing ith the

smear. The Iuice o$tained is smeared onto a slide (Slide /) ith standard thic"ness and

diameter and! alloed to dry. The slide is then %gently& flamed to fi the smear.

Staining and reading the smears

Smears are stained $y iehlNeelsen9s method. After staining! slides are eamined using

a 4== oil immersion lens. 1acilli are seen as red dots against a $lue $ac"ground. ?iving

(via$le) leprosy $acilli appear uniformly stained' they are descri$ed as solidstaining or

%solids& (S) $acilli. Eead leprosy $acilli! that stain irregularly! are descri$ed as fragmented

(-) and granular (H). (Slides 6! 5)

The total num$er of the $acilli is recorded as the $acterial inde (13). The percentage of

solidstaining $acilli is the morphological inde (M3) (Slides 4= and 44). Lariations of the 13

along the spectrum are reported in Part 3.! Slide 22.

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