Comprehensive electrophysiology in leprous neuropathy - Is there a clinico-electrophysiological dissociation?

Objective: The diagnosis of leprous neuropathy is mostly empirical and electrophysiological studies may not truly represent the clinical findings. This study comprehensively evaluates the neuroelectrophysiology and looks at clinico-electrophysiological dissociation.

Methods: Conventional electrophysiological recording included evaluation of median, ulnar, radial, tibial, and common peroneal nerve; an extended protocol included great auricular, phrenic, and facial nerves, along with sympathetic skin response and blink reflex. Nerve biopsy and slit skin smear were done to aid categorization.

Results: Forty-six patients of leprosy were enrolled. Mononeuritis multiplex was the commonest presentation. Sensory loss was commoner than motor deficits. Approximately 60% of all cases were nerve-biopsy proven. Nerve thickening was present in 38.7% (214/552) of nerves examined. Clinico-electrophysiological dissociation between nerve thickening and nerve conduction findings was present in median, ulnar, great auricular, and common peroneal nerves.

Conclusion: Electrophysiological findings outnumber occurrence of nerve thickening and clinical deficits in leprous neuropathy. From a clinical perspective, enlargement of great auricular, ulnar, and common peroneal nerves may be more sensitive in predicting electrophysiological abnormalities.

Significance: A comprehensive nerve conduction study including great auricular and phrenic nerves, coupled with a sympathetic skin response, may aid in detecting cases with paucity of findings since such a combination is seldom seen in other disorders.