Neuritis, acute and chronic, in leprosy

Leprosy Mailing List – February 28^th, 2012 

Ref.:    Neuritis, acute and chronic, in leprosy

From:  H Srinivasan, Chennai, India

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Dear Dr Noto,

The following are my views regarding the queries raised about "Acute neuritis" in leprosy.  I think it will help starting from the definition of neuritis and then considering acute and chronic neuritis.  I also report some relevant aspects of histopathology.

Definition of leprosy neuritis

Leprosy neuritis is an inflammatory mononeuropathy occurring in leprosy.  In can be acute or chronic.

Acute leprosy neuritis 

Acute leprosy neuritis describes the clinical state characterized by pain occurring in an obviously thickened peripheral nerve trunk such as ulnar, median, lateral popliteal nerve etc.  It may occur in cutaneous nerve trunks also, but here there is no risk of disability and deformity, although the condition may be quite distressing to the patient.  Acute neuritis is of rapid (i.e., acute) onset, over the course of a few hours to a few days.  It may have been present for a few days to a few weeks by the time the patient is seen by the physician or paramedical worker.

It may be moderately severe or severe.  In moderately severe acute leprosy neuritis patient complains of severe pain, but the movement of adjacent joint is not restricted and sleep is not disturbed because of pain.  In severe acute leprosy neuritis patient complains of severe pain and the movement of adjacent joint is restricted due to the pain and patient admits that pain disturbs sleep. 

Often, acute neuritis occurs in a background of chronic neuritis.  Acute neuritis may occur along with cutaneous manifestations of type I or type II reaction, or as an isolated clinical manifestation of the reactional process.

The term “acute leprosy neuritis" when used in the histopathological context indicates presence of foci of polymorpho nuclear leucocyte infiltration in the nerve (micro or macro “hot abscess”).

Chronic leprosy neuritis

 “Chronic leprosy neuritis” is the clinical condition where there has been long standing ‘mild’ (patient admits to having pain in the nerve only on asking about it) to ‘moderate’ nerve pain (complains of pain even without asking about it, but says it is not severe) in one or more peripheral nerve trunks of the limb(s).   

Histologically, every case of leprosy shows some evidence of chronic neuritis at some site in the peripheral nervous system.  Leprosy is not diagnosed without such evidence.   

Clinical examination

On examination, the concerned nerve trunk is obviously thickened (swollen), and very tender (very painful on palpation), such that the patient is afraid of palpation of the nerve.  Range of active movement of the adjacent joint is restricted because of pain; and/or passively increasing the range aggravates pain in the nerve.  There may be clinical nerve function deficit relating to the affected nerve trunk, which may be pre-existing or of recent origin along with the attack of acute neuritis or, pre-existing nerve function deficit may have worsened coincident with the attack of acute neuritis or, there may not be any clinically identifiable nerve function deficit.  

Indications for Steroid therapy

Onset or worsening of clinical nerve function deficit relating to the affected nerve trunk (eg., sensory loss, muscle weakness or paralysis) along with acute neuritis or even while the condition is under treatment with other drugs is an absolute indication for immediate institution of steroid therapy in adequate dosage.  Continued severe nerve pain even in the absence of increasing nerve function deficit or in a destroyed nerve trunk (with no possibility of the nerve recovering) despite adequate analgesic therapy is often relieved by steroid therapy.

Nerve conduction studies

One does not wait for or depend on nerve conduction studies for diagnosing and treating acute neuritis.  They may be used, when available, for monitoring efficacy of therapy.  Nerve conduction velocity (NCVs) may be within normal limits when only slow conducting fibres are damaged.  Marginal improvement in NCVs without clinical improvement is of no material benefit to the patient.

Early detection of leprosy neuritis

Patient is the best person to suspect early the possibility of acute neuritis and report for treatment without delay.  So the patient should be trained to look for and suspect acute neuritis as well as onset/worsening of nerve function deficit of his or her thickened nerve trunks.  The paramedical and medical personnel must be sensitized to show concern and examine the patient very carefully and sympathetically when a patient reports for suspected acute neuritis and not play down or neglect the patient.  It goes without saying that they must know how to examine such patients.

H Srinivasan, FRCS
Surgeon (Retd)
25 First Seaward Road
Chennai - 600 041
INDIA