Top of Basilar Syndrome Presenting With Hyperekplexia Initially Diagnosed as a Convulsive Status Epilepticus

Background: Hyperekplexia is a rare neurologic disorder characterized by pronounced startle responses to tactile or acoustic stimuli and increase tone. Acquired hyperekplexia is usually seen in brainstem pathologies and when it develops acutely it can be easily misdiagnosed as a convulsive seizure.

Case report: A 38-year-old man presented with acute onset generalized brief involuntary jerky movements and a decreased level of consciousness. He was initially diagnosed with convulsive status epilepticus for which he received multiple antiseizure medications without any improvement. Further investigations revealed abnormal oculocephalic reflex response and that his movements were in fact hyperkeplexia caused by brainstem infarction with basilar artery thrombus secondary to right vertebral artery dissection. Emergent thrombectomy was performed and he was eventually discharged to a rehabilitation facility. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians should be aware of hyperekplexia and how to differentiate it from convulsive stats epilepticus because the pathology and the emergent treatment of these 2 serious conditions are different. An underlying acquired brainstem pathology (especially basilar artery thromboembolism) should be suspected in any patient with untypical convulsive like movements along with focal neurologic signs compatible with brain stem pathology even when computed tomography imaging is normal. © 2020 Elsevier Inc.

Keywords: acquired hyperekplexia; basilar artery thromboembolism; brainstem; convulsions; epilepsy; hyperekplexia; infarction; rostral brain stem infarction; startle syndromes; top of the basilar syndrome.