Intracranial Pressure Fluctuations Mimicking Seizures in a Patient With Shunt Malfunction

This case describes a patient with new onset of multiple daily paroxysmal stereotyped episodes with alteration of arousal and responsiveness. These episodes pose a diagnostic challenge because they may be misdiagnosed as epileptic seizures because of stereotypy, similarities in semiology, risk factors such as structural abnormality, and rhythmic EEG pattern. A 20-year-old woman with Chiari malformation, spina bifida, and ventriculoperitoneal shunt presented with paroxysmal episodes of change in responsiveness, concerning for seizure activity. Anti-seizure medication was started without amelioration. During the stereotyped episodes, she suffered from paroxysmal headache, drowsiness, poor responsiveness, and relative bradycardia. EEG confirmed relative bradycardia and revealed rapid buildup of generalized rhythmic delta activity without ictal features. Improvement with ICP lowering, and lack of epileptiform activity on EEG or localizing ictal semiology, prompted obtaining shunt imaging and brain MRI. The patient was subsequently diagnosed with shunt malfunction and underwent shunt revision, resulting in complete resolution of her paroxysmal spells. Although common differential diagnosis of brief paroxysmal stereotyped spells includes seizures or psychogenic nonepileptic attacks, this patient's case demonstrates clinical paroxysms caused by intracranial pressure fluctuations (plateau waves). When evaluating patients with possible intracranial pressure abnormality for paroxysmal spells, shunt malfunction should be considered as well.