Criteria for diagnosis of pure neural leprosy

Márcia R. Jardim, Sérgio L. G. Antunes, Adalberto R. Santos, Osvaldo J. M. Nascimento, Jose Augusto C. Nery, Anna M. Sales, Ximena Illarramendi, Nádia Duppre, Leila Chimelli, Elizabeth P. Sampaio, Euzenir P. N. Sarno

The clinical diagnosis of pure neural leprosy (PNL) remains a public health care problem mainly because skin lesions-the cardinal features of leprosy-are always absent.Moreover, the identification of the leprosy bacillus is not easily achieved even when a nerve biopsy can be performed. In an attempt to reach a reliable PNL diagnosis in patients referred to our Leprosy Outpatient Clinic, this study employed a variety of criteria. The nerve biopsies performed on the 67 individuals whose clinical, neurological, and electrophysiological examination findings strongly suggested peripheral neuropathy were submitted to M. leprae identification via a polymerase chain reaction (PCR). Mononeuropathy multiplex was the most frequent clinical and electrophysiological pattern of nerve dysfunction, while sensory impairment occurred in 89% of all cases and motor dysfunction in 81%. Axonal neuropathy was the predominant electrophysiological finding, while the histopathological nerve study showed epithelioid granuloma in 14% of the patients, acid fast bacilli in 16%, and nonspecific inflammatory infiltrate and/or fibrosis in 39%. PCR for M. leprae was positive in 47% of the nerve biopsy samples (n=23). PCR, in conjunction with clinical and neurological examination results, can be a powerful tool in attempting to identify and confirm a PNL diagnosis.