Hashimoto's encephalopathy with gait disturbance caused by sensory ganglionopathy: A case report and review of the literature.

Hashimoto's encephalopathy (HE) is a steroid-responsive encephalopathy characterized by several neurological symptoms. HE mainly involves the central nervous system; the peripheral nervous system is rarely involved. We treated a previously healthy elderly man showing mild cognitive decline and subacute progressive gait disturbance due to severe sensory deficits, including sensation of touch and deep sensation with elevated anti-NH2 terminal of α-enolase and anti-thyroid antibodies. His sensory disturbance symptoms improved after steroid therapy, suggesting that the neuropathy was related to HE. His disease was characteristic of HE in that his sensory deficits responded well and rapidly to steroid therapy. A nerve conduction study showed reduced sensory nerve action potentials in all limbs, indicating that his neuropathy was not "axonopathy", but "sensory ganglionopathy", which can occur concurrently with autoimmune disorders. Dysautonomia may be the responsible pathomechanism because of the vulnerability of the blood-nerve barrier at the ganglia. Although the pathophysiology of HE has not been clearly elucidated, autoimmune inflammation has been reported in a number of autopsy cases, indicating that sensory ganglionopathy can develop with HE. Therefore, HE should be recognized as one type of "treatable neuropathy".