Tremor of the mouth floor and anti-glutamic acid decarboxylase autoantibodies

Involuntary movements of the mouth can present as palatal tremor, which is frequently associated with hypertrophy of the inferior olivary nucleus and can be accompanied by contraction of other muscles of the head. We report the case of a 39-year-old man with autoimmune thyroiditis and diabetes who complained of involuntary rhythmic tremor involving the muscles of the floor of the mouth, which interfered with breathing and swallowing. Cerebrospinal fluid (CSF) examination showed the presence of oligoclonal bands and screening for anti-neuronal antibodies revealed high titres of anti-glutamic acid decarboxylase autoantibodies (GAD-Ab). Tremor responded to treatment with benzodiazepines. The correlation between the tremor and antibody positivity is unclear although an alteration of the gabaergic system mediated by the antibodies may be hypothesised on the basis of an inflammatory CSF profile.