Abstract

A 36-year-old man with relapsed IgG-kappa multiple myeloma presented with bilateral lower extremity weakness and ptosis. Contrast-enhanced brain MRI demonstrated linear enhancement of multiple cranial nerves, including bilateral oculomotor (III), trochlear (IV), trigeminal (V), facial–vestibulocochlear (VII–VIII), glossopharyngeal–vagal (IX–X), and right abducens (VI) nerves. The enhancement pattern was predominantly linear without nodular mass formation or foraminal widening. No diffusion restriction or abnormal FLAIR signal was observed. Spinal MRI revealed nodular leptomeningeal involvement of the conus medullaris and cauda equina nerve roots. In correlation with systemic relapse, imaging findings were attributed to central nervous system progression of multiple myeloma. This case highlights that extensive cranial nerve enhancement, particularly when accompanied by nodular cauda equina involvement, may represent leptomeningeal dissemination in advanced disease.

Key words: Multiple myeloma; Cranial nerve enhancement; Leptomeningeal dissemination; Magnetic resonance imaging