Taavi Saavalainen MD, Presenter: Nothing to Disclose

Leena Jutila, Abstract Co-Author: Nothing to Disclose

Esa Mervaala MD, PhD, Abstract Co-Author: Nothing to Disclose

Arto Immonen MD, PhD, Abstract Co-Author: Nothing to Disclose

Reetta Kalviainen, Abstract Co-Author: Nothing to Disclose

Ritva Liisa Vanninen MD, Abstract Co-Author: Nothing to Disclose

To report the increasing frequency of temporal anteroinferior encephalocele diagnosis in our tertiary care epilepsy center and to illustrate mainly the imaging characteristics of this condition in a series of 19 patients. Altogether 22 patients have been reported in the literature, largest series being 3 patients.

Epilepsy patients diagnosed with temporal anteroinferior encephalocele during the study period (January 2007 - March 2013) in our hospital were included. All patients had MRI examinations (mainly 3T, Philips Achieva TX) according to an epilepsy protocol which was complemented with additional sequences. 3D-CT and PET-CT were acquired from surgical candidates when necessary.

Nineteen epilepsy patients (12 females, mean age 40 years) were diagnosed with temporal anteroinferior encephalocele. Eleven patients had two or more encephaloceles and five patients had bilateral encephaloceles. The estimated prevalence of this condition was 0.3% in MRI examinations performed due to newly diagnosed epilepsy (n=4) and 2.2% in drug-resistant patients referred to our institute as epilepsy surgery candidates (n=15). High-quality, thin-slice, preferably three-dimensional MRI and computed tomography studies facilitated the detection of this condition. The mean of maximal diameter of the lesions was 11.6 mm (range, 3-48 mm) and the mean of maximal diameter of the bony defect orifice was 8.7 mm (range, 3-46 mm). PET-CT showed temporal lobe hypometabolism in 6/9 patients, all were ipsilateral to the lesion. Ten patients had epilepsy surgery. Patients with local encephalocele disconnection (n=3) or anterior temporal lobectomy and amygdalohippocampectomy (n=5) have become seizure free in a mean 1.6 years (range 3 months - 3 years) of follow up. The remaining two surgically treated patients are very recent and lack follow up data. Histologically gliosis was present in temporal lobe samples in all surgically treated patients and encephaloceles also showed cortical laminar disorganization.

The possibility of temporal encephalocele should be considered when interpreting MRI examinations of patients with medically intractable temporal lobe epilepsy. These patients can significantly benefit from epilepsy surgery.

Identifying temporal anteroinferior encephalocele as the cause for medically intractable epilepsy is important as these patients are excellent candidates for epilepsy surgery.

Saavalainen, T, Jutila, L, Mervaala, E, Immonen, A, Kalviainen, R, Vanninen, R, Temporal Anteroinferior Encephalocele: A Poorly Recognized Etiology of Temporal Lobe Epilepsy?.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13027609.html