A case of glycine-receptor antibody-associated encephalomyelitis with rigidity and myoclonus (PERM): Clinical course, treatment and CSF findings

Over several months a 58-year-old man developed muscle stiffness, myoclonus and experienced several sudden falls caused by sensory and acoustic stimuli. On neurological examination, a severe startle reaction could be triggered by unexpected noises and there was stiffness, especially of the back and lower limb muscles, with myoclonus, lower limb paraparesis, muscle rigidity and increased tendon reflexes without further pyramidal signs. He was not able to walk without help. He also exhibited a mild pontine syndrome with disturbed smooth pursuit eye movements and diplopia. Electrophysiological studies revealed ubiquitous early recruitment and continuous motor unit activity as described for stiff person syndrome by Meinck and Thompson [ 1]. Cerebral MRI scans were normal. Antibodies against glutamic acid decarboxylase (GAD), amphiphysin, CYFRA 21-1, CEA, Ri, Hu, Yo, MA1, MA2, CV2 and CRMP5 could not be detected in serum. Neuron-specific enolase (NSE) enzyme concentrations were...