Recognising Lewis–Sumner syndrome in chronic asymmetric sensorimotor neuropathy

Abstract

Lewis–Sumner syndrome, or MADSAM, is a treatable CIDP phenotype that may resemble mononeuritis multiplex because of its asymmetric, multifocal sensorimotor presentation. We report a 28-year-old man with progressive asymmetric distal limb weakness, impaired hand function, sensory ataxia, patchy sensory loss, reduced reflexes, elevated cerebrospinal fluid protein with normal cell count, and multifocal demyelinating nerve conduction abnormalities with conduction block. Alternative causes were excluded clinically and electrophysiologically. He improved after intravenous immunoglobulin. This case highlights the importance of considering Lewis–Sumner syndrome in chronic asymmetric sensorimotor neuropathy with multifocal distal weakness, patchy sensory loss, and reduced reflexes.