Epilepsy Associated with Temporal Pole Encephaloceles : An Unrecognized Manifestation of Idiopathic Intracranial Hypertension?

PURPOSE: We hypothesized that epilepsy associated with temporal pole encephaloceles (ETPE) could be the consequence and an unrecognized manifestation of idiopathic intracranial hypertension (IIH). To test this hypothesis in patients with ETPEs we evaluated: 1) the frequency of two radiological signs of IIH and 2) whether these patients develop over time clinical manifestations suggestive of elevated intracranial pressure (ICP). METHODS: Case-control study comparing two cardinal radiological signs of IIH pituitary gland height (PGH) and the diameter of the two optic nerve sheaths (ONS) between 29 patients with ETPEs (TPE group) and 29 patients with focal epilepsy of other etiologies (control group), adjusted by age, sex, body mass index (BMI), age at epilepsy onset and epilepsy duration. Analysis was performed using conventional and ordinal logistic regression. The measurements in both groups were compared with validated radiological criteria of IIH. RESULTS: Of the patients 17 (63%) in the TPE group had all three measurements over the cut-off values for IIH, while no patients in the control group had all three findings. The TPE group patients had lower PGH (3.2 ± 1.0 mm vs. 4.9 ± 1.3 mm, p < 0.001) and larger diameter of ONS than controls (p < 0.001), being similar to validated data of IIH. No patient with TPE had clinical manifestations of elevated ICP (mean follow-up 15.1 ± 11.7 years). CONCLUSION: Patients with ETPEs frequently had radiological signs of IIH while not developing typical manifestations of elevated ICP over time. In this way, ETPEs could be an unrecognized manifestation of IIH, and temporal lobe seizures the only clinical expression of this epilepsy syndrome.