Abstracts

Rationale: Temporal lobe epilepsy (TLE) is the most common localized type. Its causes include mesial temporal sclerosis, cortical developmental disorders, injury etc. About one third of the TLE patients are drug-resistant. Temporal encephalocele is a rare cause of drug resistant temporal epilepsy. Temporal polar meningoencephalocele is often overlooked in medical imaging and clinical practice. Surgical treatment appears to be the best therapy for this group of patients. Here we report 3 "lesion negative" drug resistant temporal epilepsy patients Methods: Three patients included in the study, 2 male (MJ and CS), 1 female (AR) at the ages of 35, 9 and 28 years. All three patients underwent CT and MRI in various institutions. Two patients have weekly seizures, one have one seizure in 2-4 weeks despite formal drug treatment. The video EEG monitoring was acquired at Children's Hospital of St Paul and United Hospital. The MEG was performed at MSI lab of Minnesota Epilepsy Group and Allina Health. The MEG equipment is a whole head system with 148 channel magnetometer housed in a magnetically shielded room. Results: Two patients' (MJ and CS) EEG demonstrates left frontal temporal epileptiform discharges interictal and ictally, the other one (AR) has frequent interictal epileptiform discharges bilaterally, the seizure recorded from right temporal lobe. MEG/MSI demonstrate left temporal epileptiform discharges in MJ (Figure 1). No seizure activity recorded for CS. Frequent bilateral temporal epileptiform discharges recorded for AR. The cases were presented at multidisciplinary epilepsy surgery conferences. Re-review of neuroimaging revealed left temporal meningoencephalocele in MJ and CS, bilateral temporal meningoencephalocele in AR. Figure 2 demonstrates the encephalocele on coronal T1 and T2 weighted MR images. Left anterior temporal polar resection and repair of middle fossa encephalocele were performed for MJ and CS. Right anterior tip temporal lobectomy and closure of meningolocele for AR. MJ and CS have been seizure free with longer than 2 years follow-up. AR's seizure improved with 2 seizures in the first 6 months after surgery. She passed away before the second follow-up. Conclusions: In "occult" temporal epilepsy patients, multidisciplinary approach and reevaluation of multimodality neuroimaging should be considered to rule out the rare causes, such as encephalocele. Guided by CT, MRI, MSI, and/or invasive EEG, repairing bone and dural defect and resection of the herniated and epileptogenic tissue may be able to cure the seizure. Funding: N/A