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  • Author or Editor: Kostas N. Fountas x
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Kostas N. Fountas and Joseph R. Smith

✓Friedrich Goltz first reported in the 1890s that temporal lobe removal had a taming effect in animals. The results of studies by Klüver and Bucy, and later Terzian and Ore, demonstrated that an amygdalectomy combined with a temporal lobectomy had a significant taming effect in both animals and humans. Based on these observations, Narabayashi and colleagues reported the first clinical series of patients with temporal lobe epilepsy and/or severe behavioral disturbances in which stereotactic amygdalotomy was performed to address aggressive disorders, using a frame-based stereo-tactic device designed by Narabayashi. Use of pneumoencephalography, combined with physiological localization by means of olfactory stimulation and field potential recordings, enabled these investigators to define the lateral part of the amygdala, while simultaneously using wax injections to create lesions. Chitanondh used a similar localization technique to produce medial amygdala lesions by injecting a mixture of olive oil, wax, and iodized oil.

In 1966, Heimburger and coworkers reported results from a series of 25 patients with epilepsy and aggressive behavior who underwent stereotactic amygdalotomy. Their technique was slightly different and their target localization was solely anatomical, based on pneumoencephalography or contrast ventriculography, and they utilized a cryoprobe to make lesions. In 1970, Balasubramaniam and Ramamurthi reported the largest clinical series to date on this technique; pneumoencephalography or contrast ventriculography was used for anatomical localization, and depth electrode recordings were used to obtain physiological confirmation of their targets, whereas either diathermy or a Bertrand loop was used for making lesions. The development of magnetic resonance imaging technology in late 1980 allowed for a more accurate anatomical localization of the amygdala, and the improvement of radiofrequency generators also made lesioning more precise. Despite these and subsequent technological advances, the number of amygdalotomies performed has geometrically decreased during the last 20 years.

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Kostas N. Fountas, Joseph R. Smith, Patrick D. Jenkins and Anthony M. Murro

Several cases of congenital or acquired temporal encephaloceles have been reported in the literature as the causative mechanism of simple and/or complex partial seizures. In this report the authors describe a rare case of spontaneous parietal encephalocele presenting with simple partial seizures and progressively increasing contralateral upper-extremity motor deficit. The unusual anatomical location of an encephalocele associated with seizures and the delayed seizure onset represent distinctive characteristics in this case. Preoperative imaging included surface electroencephalography, computerized tomography, and brain magnetic resonance imaging. Frameless neuronavigation and intraoperative cortical mapping were used to aid resection of the encephalocele, and the dural and bone defects were reconstructed. The surgical outcome in this case was excellent, and the patient has remained seizure free. The pertinent literature is reviewed in this report.

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Kostas N. Fountas, Joseph R. Smith, Gregory P. Lee, Patrick D. Jenkins, Rebecca R. Cantrell and W. Chris Sheils

Object

Stereotactic radiosurgery (SRS) with the Gamma Knife (GK) is a rapidly emerging surgical modality in the management of medically refractory idiopathic trigeminal neuralgia (TN). The current study examines the long-term outcome in patients with drug-resistant idiopathic TN who underwent GK surgery at the authors‘ institution.

Methods

One hundred and six consecutive patients (38 men and 68 women) with proven medically refractory idiopathic TN were included in this retrospective study. Their ages were 41–82 years (mean 72.3 years). All patients underwent SRS with prescribed maximal radiation doses ranging from 70 to 85 Gy. Isocenters 1–3 were used and plugging was used selectively. The follow-up period was 12–72 months (mean 34.3 months). The patients were divided into 2 groups according to their history of previous surgery.

Results

The initial response rate in patients with no history of previous surgery was 92.9%; in those who had undergone previous surgery, the initial response rate was 85.7%. At the end of the 1st posttreatment year, an excellent outcome was achieved in 82.5% of patients who had not had previous surgery, and in 69.4% of those who had. The respective outcome rates for the 2nd posttreatment year were 78 and 63.5%, respectively. The most common complication was the development of persistent paresthesia, which occurred in 15.8% of patients with no previous surgery and 16.3% of those with previous surgery.

Conclusions

Stereotactic radiosurgery with the GK is a safe and effective treatment option for patients with medically refractory idiopathic TN.

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Kostas N. Fountas, Ioannis Tsougos, Efstathios D. Gotsis, Stylianos Giannakodimos, Joseph R. Smith and Eftychia Z. Kapsalaki

Object

The purpose of this prospective study was to compare the results of proton MR spectroscopy (MRS) in temporal poles in patients with unilateral mesial temporal sclerosis (MTS) with the histopathological findings of the resected temporal poles.

Methods

A total of 23 patients (14 male and 9 female) with a mean age of 25.2 years (range 17–45 years) were included in this study, which was conducted over a 4-year period. All patients suffered medically refractory epilepsy due to unilateral, MRI-proven MTS, with no other imaging abnormalities. All participants underwent preoperative single-voxel proton MRS using a 3-T MRI unit. The hippocampi and temporal poles were examined bilaterally. The concentrations of N-acetyl-aspartate (NAA), choline (Cho), and creatine (Cr) were measured, and the NAA/Cho, NAA/Cr, and NAA/Cho+Cr ratios were calculated. All patients underwent anterior temporal lobectomy and ipsilateral amygdalohippocampectomy, and surgical specimens from the temporal poles were sent for histopathological examination. Comparisons of the spectroscopic and histopathological results of the resected temporal poles were performed. The modified Engel classification system was used for evaluating seizure outcome in the cohort.

Results

The preoperative spectroscopic profiles of the sclerotic hippocampi were abnormal in all patients, and the contralateral hippocampus showed altered spectroscopic findings in 12 patients (52.2%). Spectroscopy of the temporal poles demonstrated severely decreased concentrations of NAA, markedly increased concentrations of Cho, and increased concentrations of Cr in the temporal pole ipsilateral to the MTS in 15 patients (65.2%). Similarly, the NAA/Cho, NAA/Cr, and NAA/Cho+Cr ratios were severely decreased in the temporal pole ipsilateral to the MTS in 16 patients (69.6%). Histopathological examination of the resected temporal poles demonstrated ischemic changes in 5 patients (21.7%), gliotic changes in 4 (17.4%), demyelinating changes in 3 (13.0%), and microdysplastic changes in 1 patient (4.3%). Comparisons of the spectroscopic and histopathological findings showed that the sensitivity of proton MRS was 100%, its specificity was 80%, its positive predictive value was 87%, and its negative predictive value was 100%. The mean follow-up time in this study was 3.4 years. At the end of the 2nd postoperative year, 17 patients (73.9%) were in Engel Class I, 5 (21.7%) were in Class II, and 1 (4.3%) was in Class III.

Conclusions

Proton MRS detected altered ipsilateral temporal pole metabolism in patients with unilateral MTS. These metabolic changes were associated with permanent histological abnormalities of the temporal pole. This finding demonstrates that MTS may be a more diffuse histological process, and exact preoperative knowledge of its temporal extent becomes of paramount importance in the selection of the best surgical approach in these patients. Further validation of the observations is necessary for defining the role of temporal pole proton MRS in cases of temporal lobe epilepsy.