Antibodies to potassium channels (VGKC-Ab) were first associated with acquired neuromyotonia and its variant with CNS involvement, Morvan’s syndrome.1 Recently, VGKC-Ab were found in patients with non-paraneoplastic limbic encephalitis (LE), characterised by personality changes, seizures and memory impairment.2 These patients may respond to immunotherapies. Thus the association of VGKC-Ab and non-paraneoplastic LE established the concept of a potentially reversible autoimmune encephalopathy.2 We describe a patient with startle syndrome and VGKC-Ab, without neuromyotonia or LE, who responded dramatically to plasma exchange (PE) and immunosuppression, adding to the spectrum of disorders associated with VGKC-Ab.

The patient was a 54-year-old female. Hypothyroidism was diagnosed at the age of 30 years. At the age of 52 years, sudden falls without loss of consciousness occurred. Two months later, massive muscle jerks appeared, spontaneously or elicited by auditory and somatosensory stimuli. The frequency of jerks increased during the ensuing months, together with mild gait impairment and scanning speech. Brain MRI was normal; CSF was normal except for the presence of oligoclonal bands. Prednisone (50 mg/day), gabapentin and levetiracetam were prescribed without improvement. Low doses of clonazepam were poorly tolerated and not effective. She was admitted to our institution in December 2003. Physical examination showed spontaneous and stimuli induced massive limb jerking, very …