Pathology and pathogenesis of leprous neuritis: a preventable and treatable complication

In conclusion, it may be said that many advances have been made in the diagnosis, treatment and prevention of nerve damage. It is now a well accepted fact that the affinity of M. leprae for Schwann cells and the property of M. leprae to grow in cooler sites of the body have made certain segments of nerve trunks vulnerable. Trauma that supervenes the inflammation and swelling severely aggravates the nerve damage. The reactive phase in all forms of leprosy, the etiology of which is not clearly understood, produces intraneural caseous necrosis in tuberculoid disease and microabscesses in lepromatous disease, causing much irreversible damage to nerves. The steroid treatment that is administered during the reactive phase has helped greatly to stop further damage, although the damage already done to nerves is not always reversible. Preventive measures like detecting the disease before nerve trunks are infected and offering prompt and adequate antileprosy therapy as early as possible have helped to reduce the prevalence of deformities. It is hoped that administering steroids along with antileprosy therapy to prevent active inflammation and or fibrosis of the nerve will reduce the prevalence of nerve damage significantly. Measures which provide rest for the infected nerve to prevent trauma should be explored.

Vascular changes in leprosy and its role in the pathogenesis of leprous neuritis

The arteriographic pattern of left hand vessels was studied in 20 patients in leprosy by percutaneous brachial arteriography. Arteriographic abnormalities noted consisted of occlusion, narrowing, tortuosity, dilatation, irregularity and incomplete filling of the lumen by contrast medium. Such abnormal findings were seen in all the arteriograms studied and more than one vessel involvement was noted in over 50 percent cases. This study clearly demonstrated that arterial involvement in leprosy was frequent. No correlation was found between motor weakness and vascular abnormalities. There was no difference in arterial lesions between the patients with and without trophic changes. There was also no correlation between the severity of vascular changes and decline in motor nerve conduction. Degree of histopathological abnormalities in the sural nerve biopsy from these patients showed no features of micro angiopathic neuropathy. It is concluded that the observed vascular abnormalities do not contribute significantly in the genesis of neurological deficit in leprosy.

Bilan de recherches physiopathologiques sur la nevrite lepreuse: 1-role de la temperature, des microtraumatismes par elongation ou subluxation nerveuse et de la striction canalaire / ?

(Role of temperature, microtraumatisms by elongation or subluxation and canalar stricture.)Cold has a slight aggravating effect on leprosy which is observed in some countries as Iran, South Russia, North India and the Andean cordillera. The subluxation of the ulnar nerve has facilitating effect in the development of the neuritic damage in a limited number of patients. The elongation is important for the production of the ulnar neuritis. The canalar stricture is a major factor causing nerve damage in leprosy. It explains the segmentary localization of the principal damages of the leprous nerves in the proximal areas situated above the tunnels. Intraneural hypertension appears first and is responsible for the swelling of the nerve which gets entraped inside the tunnel. A circulus viciosus is, then, created which maintains and aggravates the intraneural hypertension

Considerações sôbre a condução nervosa periférica na hanseníase

Em 16 pacientes de hanseníase, com sinais clínicos da neuropatia periférica, os autores estudaram o tempo de condução do impulso nervoso em 38 territórios, 22 correspondentes ao nervo ulnar e 16 ao nervo poplíteo lateral. Os valores encontrados se situam entre os valores classicamente admitidos como normais, ao contrário do que acontece em outras formas de neuropatias crônicas. A origem e o mecanismo destes achados são discutidos, supondo os autores que sua explicação se deve à ativação das fibras periféricas por um processo compressivo-isquêmico, determinado pela instalação da lesão leprótica do nervo. Recomendam a medida do tempo de condução do impulso nervoso como auxiliar do diagnóstico diferencial da neurite leprótica com outras neuropatias periféricas.

The histological aspects of leprous neuritis

This study of leprotic neuritis deals with such lesions in (a) nodular leprosy, (b) pure nerve leprosy, (c) tuberculoid leprosy, and (d) terminal nerve branches in relation to leprotic skin lesions of various kinds. In the neuritis of nodular leprosy the infiltration consists essentially of Virchow´s vacuolized cells full of Hansen bacilli, insinuated between the nerve fibers, which are compressed and secondarily destroyed. In the neuritis of pure nerve leprosy there appear between the nerve fibers small infiltrative foci consisting essentially of lymphocytes. Intense fibrosis follows, and in this tissue calcareous salts may be deposited. Bacilli are as a rule very scanty. In tuberculoid neuritis the infiltration located between the nerve fibers is composed essentially of epithelioid cells, giant cells and lymphocytes; caseation and calcification may also accur. Bacilli are pratically not demonstrable. When the nerve branches ending in skin lesions of leprosy are affected, as they very frequently are, they show primarily slight leprotic infiltrations around the perineurium. In a more advanced stage the latter is destroyed, the nerve appearing to be invaded by the infiltration, which compresses the nerve fibers until they are completely destroyed.