564 Facio-brachial dystonic seizures and autoimmune encephalitis – a post COVID-19 neurological presentation?

BackgroundFacio-brachial dystonic seizures (FBDS), which affects the ipsilateral face and arm, is a disorder in the watershed between epilepsy and movement disorders, and a transitional presentation of limbic encephalitis.It is rarely described in children.ObjectivesWe present an unusual case of presumed autoimmune encephalitis - with the only positive investigations being Anti-TPO antibodies and COVID-19 antibodies.Methods17-month-old male presenting with the following different, progressive event types:1) Clusters of focal motor seizures described as head and eyes deviating to the left and occasionally associated with stiffening of the upper limbs/entire body2) Focal dyscognitive seizures described as staring episodes associated with increased aggression then unresponsiveness with eyes deviating upwards to the right3) Clusters of facio-brachial dystonic seizures described as right eyelid and facial twitching with posturing upward movement of ipsilateral armThese events were associated with developmental regression mainly involving speech/language and behaviour change.This was preceded by upper respiratory tract symptoms 1-week prior.ResultsThis was associated with resistance to conventional AED’s (carbamazepine, phenytoin, clonazepam) but response to immunosuppression (steroids and IVIG).Initial EEG showed diffuse background slowing and independent right and left temporal sharp waves. This improved post immunomodulation.MRI brain was normal. CSF studies were normal (CSF acellular, protein 31 mg/dL)Autoimmune encephalitis panel by IIFT (NMDA, AMPA1, AMPA2, GLUR1/GLUR2, CASPR2, DPPX, LGI1, GABARB1/B2) negativeAnti-TPO Ab 72.1 (elevated), anti-thyroglobulin Ab and thyroglobulin negative (post methylprednsiolone pulse x2)COVID-19 IgM Ab 1.416, IgG 0.229;SARS-CoV-2 Nasopharygeal swab negativeHe was treated as presumed autoimmune/limbic encephalitis initially with steroids, followed by IVIG. Seizure frequency improved significantly 1-week post IVIG, however mild improvement in the developmental regression and altered behaviour. He continues on a tapering prednisolone dose over the next 4 months.ConclusionsThis case highlights the association of facio-brachial dystonic seizures and limbic encephalitis in a child.We have considered whether this can be attributed to Hashimoto’s encephalopathy as a post-inflammatory neurological manifestation of SARS-CoV-2.