A 73-year-old man presented with a three-month history of muscle wasting, cramps and marked weight loss. Examination revealed severe global amyotrophy ([Figure]), fasciculations, reduced deep tendon reflexes and flaccid quadriparesis. Nerve conduction studies were unremarkable. Needle electromyography showed acute and chronic partial denervation in the cervical, thoracic and lumbosacral segments. A full-body CT scan disclosed a large mass in the anterior mediastinum, which showed a type B2 thymoma.
Figure Findings in subacute motor neuronopathy. Severe muscle wasting in proximal (A) and distal muscle groups (B; black arrow). (C) Rarefaction of interference patterns in submaximal voluntary contraction, and fibrillation and positive sharp wave at rest. (D) Chest CT scan showed a large mass in the anterior mediastinum (white arrow).
Paraneoplastic neuropathies represent an expanding group of immune-mediated neuropathies associated with a known or unidentified neoplasm[1]. Pure motor neuropathy is represented by subacute motor neuronopathy[1], commonly associated with Hodgkin’s and non-Hodgkin’s lymphoma[1],[2] and, rarely, with thymoma[2].
