Somatosensory evoked potentials (SSEP) in Hashimoto encephalopathy – a case report

We report a case of Hashimoto encephalopathy with a significant reduction in amplitude of the parietal cortical component of the early somatosensory evoked potentials of the median nerve. This reduction was significant when using a frontal reference as compared to the palmar reference and showed a complete recovery after sufficient treatment.

A 43 old female patient with a change of personality including aggressive behaviour and a progressive choreatiform movement disorder was admitted to hospital with the suspected diagnosis of Huntington's disease (HD). Further investigations excluded HD and revealed a thyroiditis encephalopathy (Hashimoto) with complete clinical remission after treatment with corticosteroids.

The phenomenon of a reduced amplitude when using a frontal reference in SSEP is usually attributed to Huntington's disease and progresses with the severity of the disease. The finding is even less often described in other degenerative disorders of the basal ganglia.

To the best of our knowledge, this is the first case of these aberrant reversible SSEP abnormalities in a case of Hashimoto encephalopathy.

Further investigations have to show, if SSEP with extracephal reference could also be useful in the diagnosis of Hashimoto encephalopathy and a surrogate marker of sufficient treatment.