Korean Lepr Bull.  2002 Dec;35(2):13-28.

Leprous Neuropathy

• Lee DK

Abstract

Leprosy, one of the oldest diseases known to humans, still affects almost 10-15 million people throughout the world. Neuropathy affects 15-20% of infected individuals. Therefore leprous neuropathy is still one of the most common neuropathy in the world. It is due to infection with Mycobacterium leprae and occurs primarily in Asia and Africa. The cardinal symptom of leprosy is sensory loss caused by superficial neuropathy. Anesthetic depigmented skin lesions are an important finding and should be sought. Nerve involvement is a hallmark of leprosy. Nerve involvement is rare in other diseases, so the finding of skin lesions with enlarged nerves should raise the possibility of leprosy. Nerve involvement tends to occur with skin lesions, and the pattern of nerve involvement parrellels the skin disease. In the tuberculoid form, mononeuropathy multiplex is typical pattern, whereas asymmetrical or symmetrical polyneuropathy is most common in the lepromatous form. Motor involvement occurs in a predictable sequence as a result of nerve trunk damage to those nerves that course close to the skin surface and hence are locally cool. Nerve involved include the ulnar nerve at the elbow, the deep peroneal branch at the ankle, superficial branches of the facial nerve, and the median nerve at the wrist, and especially the greater auricular nerve. Nerve involvement without skin lesions, called pure neural leprosy, can occur. Other characteristic findings are thickened nerve, trophic ulcers, mutilated digits, and Charcot joint. In clinically affected nerves, the motor nerve conduction velocities are minimally slow. The terminal latency is often prolonged and the compound muscle action potentials are temporally dispersed and decreased in amplitude. Sensory and mixed compound nerve action potentials are often difficult to obtain or else a reduced amplitude. The facial nerve is commonly involved in leprosy. Improvement in motor nerve conduction was reported in leprosy patients under sulfone treatment. Nerve biopsy reveals subperineurial edema and various amounts of loss of myelinated and unmyelinated fibers. Teased fiber studies reveal paranodal demyelination affecting successive internodes. Therefore segmental demyelination is the main pathology in leprous neuropathy.

MeSH Terms

Action Potentials
Africa
Ankle
Arthropathy, Neurogenic
Asia
Biopsy
Demyelinating Diseases
Edema
Elbow
Facial Nerve
Humans
Leprosy
Leprosy, Tuberculoid
Median Nerve
Mononeuropathies
Mycobacterium leprae
Myelin Sheath
Neural Conduction
Pathology
Polyneuropathies
Skin
Skin Diseases
Ulcer
Ulnar Nerve
Wrist