I came into a young woman with weakness with myotonia and hyperreflexia and a persistent weakness since taking high dosage of gabapentin. Paroxysmal exacerbations are associated with severe ocular pain and cacosmia (but no seizures). Genetic testing for HSP, periodic palsy, channalopathies (included hemiplegic migraine and episodic ataxia) and myotonic disorders (included dystrophies) came back negative. MRI total body imaging, EEG, antibodies for paraneoplastic, myasthenic syndromes and LEMS, overall autoimmunity also negative. ENG/EMG was also negative, but peroneal CMAPs appear to be reduced (2mV) compared to upper limbs, with EMG normal in absence of neurogenic signs. There is a subjective but incomplete response to Piridostigmine for weakness and gabapentin for ocular pain.

What is still missing? Any suggestions?

Thanks for reading this case