This case report describes a patient presentation to the Gold Coast University Hospital in Queensland, Australia. It highlights the diagnostic utility in investigating for antibody mediated causes of pathologic electroencephalogram (EEG) findings when standard neurological work-up does not reveal a diagnosis.

A 31 year old female presented to a tertiary hospital with a 2 year history of progressive trismus, joint pains, muscle spasms, spasticity and rotatory circular movements of the feet. Background history was significant for anxiety. Extensive investigations were performed in 2017 at time of initial presentation at an external hospital. Anti-neuronal antibodies including anti-glutamic acid decarboxylase (GAD) antibodies were negative. Cerebrospinal fluid and magnetic resonance imaging were normal. A tremulous contraction in gastrocnemius muscle was noted on EMG, but there were no denervation changes. EEG showed generalized spike and wave discharges, greater on the right side. She was not treated due to the absence of clinical seizures. An initial diagnosis of functional neurological disorder was made, which was later revised to fibromyalgia. Upon recent presentation and based on a high clinical suspicion of autoimmune limbic encephalitis, anti-glycine receptor antibodies were requested which returned positive. Immunotherapy was commenced with intravenous immunoglobulin with a view to escalate further based on initial clinical response.

This case widens the possible EEG findings in autoimmune epilepsy secondary to anti-glycine receptor antibody disease. Typical EEG findings in anti-glycine receptor disease include non-specific slowing or focal epileptiform discharges, this case demonstrates generalized spike and wave activity can be present in cases of anti-glycine limbic encephalitis. Previously described anti-glycine receptor antibody disease cases with spike and wave EEG activity have only been reported in the setting of status epilepticus.