Pathology and pathogenesis of predilective sites of nerve damage in leprous neuritis

Abstract

A very brief review of the literature on the clinicopathological aspects of leprosy is given; mainly through references. The salient features of the two main types of leprosy--tuberculoid and lepromatous--are presented in a Table. The surgical and pathological findings are briefly described and the pathogenesis of involvement of the facial nerve (a motor nerve) is discussed. On the basis of (i) the severe histopathologic changes (degeneration) of the most distal part of the zygomatic branch of the facial nerve (innervating the orbicularis oculi), with sparing of the roots of all branches and the trunk of the nerve; (ii) the concurrent loss of cutaneous sensations in the territory of the maxillary division of the trigeminal nerve (the region of the zygoma and the lower eyelid); and (iii) the close approximation or even anastomoses occurring between the ultimate branches of these two nerves, it is postulated that paralysis of orbicularis oculi occurs secondarily to the sensory nerve damage, i.e. due to spread of infection from the sensory branches of the trigeminal to the motor branches of the facial nerve. The surgical and pathological findings of the nerves in the arm, especially the ulnar and the median and their branches are described, in tuberculoid and lepromatous leprosy. The forms of nerve degeneration, the occasional axon regeneration, and the role of the Schwann cell in harbouring the bacilli, are illustrated. The lysosomal enzyme activity in the Schwann cells of nerve fibres, particularly of unmyelinated fibres which preferentially phagocytose the M. leprae, and their role, albeit not very successful, in degrading the bacilli and controlling the infection, are also stressed, through light and electronmicrographs. The constellation of secondary factors of the terrain operating to produce further damage to primarily diseased nerves, is discussed. These factors include indirect compression from unyielding fibroosseous tissues, minor traumata, stretching of the nerves, and their exposure to lower temperatures in subcutaneous tissues.

Regeneration at the predilective damage sites of nerve trunks in treated leprosy

“…7 Such segments are generally considered to be the sites of the most severe damage and hence fibrosis. 4,8 To our knowledge, the present report is the first devised to study the site ofpredilective nerve involvement in treated leprosy cases suffering fr om loss of sensation. The primary goal of this study was to describe the distinctive histopathological patterns, with special attention to nerve regeneration, in the nerve trunks of advanced lepromatous (LL), borderline lepromatous (BL) and borderline tuberculoid (BT) leprosy cases that had received treatment.…”

Pulmonary dysfunction-an overt leprosy sequel: study done in a rehabilitation centre

“…14 Leprosy is one of the leading causes of severe neuropathy in the tropics and the subtropics and also the commonest peripheral neuropathy in the world as stated by Darab K. Dastur causing morbidity and permanent severe disability due to sensory loss and motor paralysis which remains the prime focus of clinical consent and research. 15 Apart from sensory loss and motor paralysis, autonomic neuropathy is reported in varying degrees as indicated by sweat function test, histamine triple response and bed side tests for cardiovascular and respiratory system involvement in Leprosy. 16 Autonomic dysfunction in leprosy was reported earlier by Arnold, from loss of sweating in patches and also by Mathur and Pasricha from reduced sweat response and vasodilatory effect.…”

Leprosy with Guillain Barre Syndrome: A New Neurologic Manifestation?

“…The dermatologic manifestations and disfigurement of Hansen's disease (leprosy) have for ages, had an indelible impact on the minds of patients and physicians. Hansen's disease is the most common cause of peripheral neuropathy worldwide due to the large number of affected individuals (1). This is because of Mycobacterium leprae's predilection for Schwann cells (2), which causes the distinctive changes associated with the peripheral neuropathy of leprosy.…”