Authors :
Presenting Author: Jan Šroubek, MD – Na Homolce Hospital
Michaela Nová, MD – Na Homolce Hospital
Matěj Červenka, MD – Na Homolce Hospital
Barbora Mikova, MD – Na Homolce Hospital
Lenka Krámská, MD, PhD, Prof – Na Homolce Hospital
Tomáš Česák, MD, PhD, Assoc.Prof. – University Hospital , Hradec Králové
Zdeněk Vojtěch, MD, PhD, Assoc.Prof – Na Homolce Hospital
Jan Klener, MD – Na Homolce Hospital
Rationale:
Temporal encephalocele (TEN) is a congenital or acquired defect in the middle cranial fossa, through which brain tissue herniates beneath the skull base. The main types are lateral, anteroinferior, and petrosal. Incidence is unknown, but they are often incidental findings. Major clinical manifestations include epilepsy, CSF leak, meningitis, and there is association with intracranial hypertension. Epilepsy associated with TEN is usually pharmacoresistant (PRE). Small or even relatively large TENs are sometimes not identified on initial MRI, and are only discovered with repeat MRI using proper protocols. There are two main surgical approaches to anteroinferior TENs: transcranial and transnasal. For the PRE patients the transcranial approach is usually chosen and consists of resection or transection of the encephalocele, skull base reconstruction, and resection of the epileptogenic temporal lobe zone according to preoperative or intraoperative examination. The transnasal approach primarily aims at encephalocele resection and skull base reconstruction for CSF leak, not refractory epilepsy.
Methods
Methods: The cohort consisted of 12 patients with temporal lobe PRE and TEN, who were indicated for resective surgery at our epilepsy surgery center at Na Homolce Hospital. Patients underwent a standard evaluation protocol for epilepsy surgery, including SEEG if indicated, and were referred for resective surgery, performed via a minipterional approach comprising resection or transection of the encephalocele, temporal pole resection, skull base reconstruction (Group A), and, in (Group B) resection of mesial temporal structures was added. Epileptological, neuropsychological, and surgical outcomes were evaluated.
Results: Eight patients (Group A) had resection of the temporal pole and encephalocele; four (Group B) also underwent resection of mesial temporal structures. One year postoperatively, 6 of 8 from Group A (75%) and all 4 from Group B (100%) were seizure-free. Histology of the encephalocele showed structural disorganization, nonspecific isomorphic gliosis, and regressive brain tissue changes. In 10 patients, the temporal pole was normal; in 2, gliotic scarring and isomorphic gliosis were present. In the hippocampal specimens, ILAE type 2 hippocampal sclerosis was seen in 3 patients, and in one, evaluation was not possible due to a large epidermoid cyst. In Group A, TEN was not seen on the first MRI in 6 cases and was detected intraoperatively in 1; in Group B, intraoperative detection occurred in 2 cases. Improvement in WAIS score (IQ) appeared in 4 (50%Group A) and in 3 (75%Group B) and in WMS - memory testing in 5 (60%GroupA) and 4 (100%GroupB). No intracranial hypertension or its MRI signs were found in any patient. There were no postoperative neurological deficits or severe surgical morbidity.
Conclusions: Surgical treatment of pharmacoresistant epilepsy caused by temporal encephalocele is effective and safe. Special emphasis should be placed on careful analysis of the initial MRI, since TEN may be overlooked, thus delaying the epilepsy surgery.
Funding: Internal Grant of Ministery of Health of Czech Republic IG No 241102