Leprous neuropathy

Abstract

Leprous neuropathy, which is due to infection of nerve cells by Mycobacterium leprae, still affects millions of people in many developing countries. The clinical and pathological manifestations are determined by the natural resistance of the host to invasion of M. Leprae. Failure of early detection of leprosy often leads to severe disability in spite of eradication of mycobacterium at a later date. In the lepromatous type, bacilli are easily found in the skin and in nerve cells including Schwann cells, endothelial cells, and macrophages. In the tuberculoid type, a strong cell-mediated immune reaction leads to formation of granulomas and destruction of cells harboring bacilli and neighboring nerve fibers. In many cases, treatment of patients with the multibacillary leprosy is complicated by reversal reaction and further nerve damage. Nerve lesions lead to a symmetrical, pseudo-polyneuritic pattern in most cases of lepromatous leprosy, which is usually associated with typical skin lesions, but pure neuritic forms occur in up to 10% of patients with lepromatous leprosy. In the pure neuropathic cases, only nerve biopsy permits diagnosis. The multifocal pattern is more common in tuberculoid leprosy. Treatment is currently based on multidrug therapy with dapsone, rifampicin, and clofazimine. The use of corticosteroids can reduce or prevent nerve damage in reversal reactions. It is important to remember that sequelae, especially sensory loss, are extremely common, which can lead to secondary trophic changes due to repeated trauma in painless areas.

Keywords: Mycobacterium leprae; leprosy; leprous neuropathy; nerve biopsy; pure neural leprosy.