Episodic encephalopathy with coma as the presenting symptom of Hashimoto's encephalopathy

Objectives: The Hashimoto's encephalopathy is a rare cause of an encephalopathy in childhood. We report of a 12-year-old boy with recurrent paroxysmal episodes of unconsciousness who was diagnosed with Hashimoto's encephalopathy.

Case report: A 12-year-old boy presents recurrent episodes of unconsciousness (Glasgow coma scale 6), vomiting and motoric agitation. The episodes last several days. At one occasion, the unconsciousness was initialized by a generalized tonic clonic seizure.

Diagnosis: The EEG during the episodes shows diffuse slow activity. During the symptom free interval the EEG is normal. A diffusion weighted MRI scan of the brain with gadolinium is also normal. In the CSF there is a small increase of protein (46mg/dl and 59mg/dl) with normal cell count. Other laboratory findings including TSH, serologic test for infectious diseases, metabolic screening (ammonium, lactate, organic acids, acylcarnitine) and neurotransmitter in the CSF are normal as well.

The diagnosis of a Hashimoto thyreoiditis was made through highly elevated antibodies against TPO as well as typical sonographic findings of the thyroid.

With a starting dose of methylprednisolon (10mg/kg/die) the boy quickly regains consciousness. Under a systemic therapy with a tapering dose of initially 2mg/kg/die the patient stays symptom free.

Conclusions: The Hashimoto's encephalopathy is a rare but important cause of an encephalopathy in childhood, because it is treatable. Recurrent episodes of coma can be a presenting symptom of Hashimoto's encephalopathy.

The diagnosis of Hashimoto's encephalopathy should be considered when there is a typical constellation of elevated thyroid antibodies, elevated protein in the CSF as well as quick relief of the symptoms under systemic administration of corticosteroids.