see also epilepsy surgery.
Patients who had a keyhole approach for temporal lobe epilepsy with over 2 years follow-up were compared with all patients who had selective amygdalohippocampectomy performed in a non-keyhole fashion over the same time period. Rates of seizure freedom were comparable in the 17 patients with keyhole surgery and the 34 individuals who had a non-keyhole approach. However, patients treated with keyhole surgery were discharged from the hospital earlier than non-keyhole patients (p=0.04), and with a shorter operative time (p=0.0001). The restricted keyhole surgical exposure has not limited the ability to perform surgery for temporal lobe epilepsy with favorable results on reducing the seizure tendency, and patients may be benefited by a minimal access technique with a more rapid recovery from surgery 1).
Yang et al. described operations they were performed through a 6-cm vertical linear incision and a low 2.5-cm keyhole craniotomy at the anterior squamous temporal bone. Resection of the anterior-most portions of the middle and inferior temporal gyri provided a cylinder-like corridor to the mesial temporal lobe. Identification of the temporal horn through a basal approach was followed by resection of the amygdala, uncus, and hippocampus-parahippocampal gyrus.
A 9-year series included 683 patients with a minimum follow-up duration of 2 years. Surgery times were short (range, 1 h 35 min to 2 h 30 min). Only a small percentage of patients had complications (1.76 %), and the rate of Engel Class I seizure-free outcome was 87 %. No overt speech problems or visual field deficits were identified. Compared with the most popular conventional trans-middle temporal gyrus approach, this technique can make the operation easier, safer, and less traumatic to functional lateral neocortex 2).
Separately, Laser interstitial thermotherapy (LITT) has found a role in the treatment of temporal lobe epilepsy because it allows the creation of a precise lesion along the amygdala and hippocampus. Although seizure control rates appear to be somewhat inferior to open temporal lobectomy and selective amygdalohippocampectomy, the procedure is generally well tolerated, and because of its minimally invasive nature, it has the potential to reach a large segment of epilepsy patients who would be good surgical candidates but have shied away from open surgery.
Anterior temporal lobectomy is curative for many patients with disabling medically refractory temporal lobe epilepsy, but carries an inherent risk of disabling verbal memory loss. Although accurate prediction of iatrogenic memory loss is becoming increasingly possible, it remains unclear how much weight such predictions should have in surgical decision making.
For patients with left temporal lobe epilepsy, quantitative assessment of risk and benefit should guide recommendation of therapy. In particular, risk for and potential impact of verbal memory decline should be carefully weighed against the degree of disability conferred by continued seizures on a patient-by-patient basis 4).
The advantage of selective amygdalohippocampectomy (SAH) over anterior temporal lobectomy (ATL) for the treatment of temporal lobe epilepsy (TLE) remains controversial. Because ATL is more extensive and involves the lateral and medial parts of the temporal lobe, it may be predicted that its impact on memory is more important than SAH, which involves resection of medial temporal structures only. However, several studies do not support this assumption. Possible explanations include task-specific factors such as the extent of semantic and syntactic information to be memorized and failure to control for main confounders 5).
Law et al., retrospectively assessed verbal memory change approximately 1 year after unilateral temporal lobe epilepsy surgery using a list learning task. Participants included 23 children who underwent temporal lobe surgery with sparing of the mesial structures (13 left), and 40 children who had a temporal lobectomy that included resection of mesial structures (22 left).
Children who underwent resection from the left lateral and mesial temporal lobe were the only group to show decline in verbal memory. Furthermore, when they considered language representation in the left temporal resection group, patients with left language representation and spared mesial structures showed essentially no change in verbal memory from preoperative to follow-up, whereas those with left language representation and excised mesial structures showed a decline. Postoperative seizure status had no effect on verbal memory change in children after left temporal lobe surgery. Finally, they found that patients with intact preoperative verbal memory experienced a significant decline compared to those with below average preoperative verbal memory.
The findings provide evidence of significant risk factors for verbal memory decline in children, specific to left mesial temporal lobe epilepsy. Children who undergo left temporal lobe surgery that includes mesial structures may be most vulnerable for verbal memory decline, especially when language representation is localized to the left hemisphere and when preoperative verbal memory is intact 6).
Boucher et al., compared preoperative vs. postoperative memory performance in 13 patients with SAH with 26 patients who underwent ATL matched on side of surgery, IQ, age at seizure onset, and age at surgery. Memory function was assessed using the Logical Memory subtest from the Wechsler Memory Scales - 3rd edition (LM-WMS), the Rey Auditory Verbal Learning Test (RAVLT), the Digit Span subtest from the Wechsler Adult Intelligence Scale, and the Rey-Osterrieth Complex Figure Test. Repeated measures analyses of variance revealed opposite effects of SAH and ATL on the two verbal learning memory tests. On the immediate recall trial of the LM-WMS, performance deteriorated after ATL in comparison with that after SAH. By contrast, on the delayed recognition trial of the RAVLT, performance deteriorated after SAH compared with that after ATL. However, additional analyses revealed that the latter finding was only observed when surgery was conducted in the right hemisphere. No interaction effects were found on other memory outcomes. The results are congruent with the view that tasks involving rich semantic content and syntactical structure are more sensitive to the effects of lateral temporal cortex resection as compared with mesiotemporal resection. The findings highlight the importance of task selection in the assessment of memory in patients undergoing TLE surgery 7).