Madras motor neuron disease (MMND): clinical description and survival pattern of 116 patients from Southern India seen over 36 years (1971-2007).

Madras motor neuron disease (MMND), MMND variant (MMNDV) and Familial MMND (FMMND) have a unique geographic distribution predominantly reported from Southern India. The characteristic features are onset in young, weakness and wasting of limbs, multiple lower cranial nerve palsies and sensorineural hearing loss. We describe the clinical features and survival pattern in 116 patients with Sporadic MMND, MMND variant and FMMND. A retrospective review of patients' medical records for clinical manifestations, electromyography, imaging, audiological and histopathology findings was performed. Over 36 years (1971 to 2007) 116 patients (men: 59; women: 57) particularly hailing from Southern India were seen. Mean age of onset was 15.8+/-7.9 years. Predominant initial manifestations were impaired hearing with wasting and weakness of distal limb muscles and pyramidal dysfunction. All patients had clinical and/or audiological evidence of hearing impairment. Patients with MMNDV in addition had optic atrophy. The overall mean survival duration was 334.9+/-27.9 months. Thus, Madras motor neuron disease is clinically a distinct entity with features of amyotrophic lateral sclerosis but with young age of onset and presence of auditory neuropathy. Studies to look for environmental and genetic basis of this intriguing disease are necessary to find the causation of this rare disorder.