To describe the clinical and radiologic characteristics of 5 patients with seizure as a symptom of idiopathic intracranial hypertension (IIH).

Patients with IIH may have atypical presentations and may not meet the classic IIH diagnostic criteria. Recent reports suggest an association between IIH and seizures in patients with temporal encephaloceles, which are frequently observed in temporal lobe epilepsy and might be an epileptogenic focus. The aim of this study is to report patients with presumed IIH and seizures associated with encephaloceles.

We report 5 patients (34-79 years old; 4 women, 1 man; body mass index mean 44.6 (25.6-60.6)) with generalized or focal epilepsy associated with encephaloceles in the basal frontal lobe or inferomedial temporal lobe. Three patients with temporal lobe encephaloceles had interictal epileptiform activity or focal temporal slowing in one or both temporal lobes. Other radiological findings included signs of chronic intracranial hypertension. Three patients had rhinorrhea from spontaneous cerebrospinal fluid (CSF) leak; all denied visual symptoms. One patient had mild papilledema, and 4 patients had chronic peripapillary changes suggesting previous papilledema. Three patients had a lumbar puncture opening pressure between 26 and 28 cm H₂O. 

These cases suggest that seizures related to basal encephaloceles likely result from untreated chronic intracranial hypertension, as can be seen in untreated or chronic IIH. Skull base meningoencephaloceles and spontaneous CSF leak are two manifestations of the same bony defects that are likely part of the expanding IIH spectrum. The diagnosis of IIH remains presumptive, especially without papilledema. Radiological findings of chronic intracranial hypertension in patients with isolated seizures should prompt funduscopic examination looking for papilledema and skull base imaging screening for basal encephaloceles that may help guide epilepsy treatment.