- Epilepsy Center, Neurosurgery Department of Yuquan Hospital Tsinghua University, Beijing, China
Epilepsy Center, Neurosurgery Department of Yuquan Hospital Tsinghua University, Beijing, China
DOI:10.4103/2152-7806.121405Copyright: © 2013 Guangming Z. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Guangming Z, Wenjing Z, Jiuluan L, Zhaohui S, Bingqing Z, Gaoxiang S, Huancong Z. Long-term therapeutic effects of corticoamygdalohippocampectomy for bilateral mesial temporal lobe epilepsy. Surg Neurol Int 14-Nov-2013;4:147
How to cite this URL: Guangming Z, Wenjing Z, Jiuluan L, Zhaohui S, Bingqing Z, Gaoxiang S, Huancong Z. Long-term therapeutic effects of corticoamygdalohippocampectomy for bilateral mesial temporal lobe epilepsy. Surg Neurol Int 14-Nov-2013;4:147. Available from: http://sni.wpengine.com/surgicalint_articles/long-term-therapeutic-effects-of-corticoamygdalohippocampectomy-for-bilateral-mesial-temporal-lobe-epilepsy/
Background:Some cases of paradoxical mesial temporal lobe epilepsy (MTLE) are shown to be bilateral MTLE (BMTLE) by intracranial electrodes. The treatment for BMTLE is difficult, which poses several questions. Can corticoamygdalohippocampectomy (CAH) be applied to treat BMTLE? What are the long-term therapeutic effects if CAH is performed in BMTLE patients?
Methods:Four patients were shown to have BMTLE through bilateral intracranial electrode implantation. CAH was performed on the side with relatively more seizure originations. These patients were followed-up at 6 months, 1 year, 2 years and longer, in some cases, after the CAH. The postoperative seizure frequency was recorded. Preoperative and postoperative clinical memory tests and a postoperative 4-hour video electroencephalography (EEG) were conducted in the hospital at different follow-up times. The average seizure frequencies and memory quotient scores were analyzed.
Results:The average seizure frequency significantly decreased by 80.8%, 83.5%, and 84.3% at different postoperative times. Although no patient was seizure free, the intensity of the seizures was reduced in all cases. The postoperative average memory quotient score was moderately decreased by 15.8%, 11.7%, and 16.6% at different postoperative times. Both the average values of the postoperative seizure frequency (5.5, 4.75, and 4.5 per month) and the average values of the postoperative memory quotient (73.7, 77.3, and 73) at different postoperative times were approximately the same.
Conclusions:CAH reduced the seizure frequency and intensity in these BMTLE patients. Mild hypomnesis occurred in every case. We observed the long-term treatment effects at 6 months after the CAH and showed that the effects did not change at that time or over the next few years.
Keywords: Mesial temporal lobe epilepsy, corticoamygdalohippocampectomy, long-term therapeutic effect, memory
Mesial temporal lobe epilepsy (MTLE) is a common epilepsy type and is usually resistant to antiepileptic drugs. Typical unilateral MTLE is associated with good outcomes after corticoamygdalohippocampectomy (CAH).[
Four cases, including three males and one female (aged 19, 22, 32, and 53 years), were studied. The duration of their medical histories was 9, 12, 15, and 33 years, and the number of antiepileptic drugs used before intracranial electrode implantation was 2, 3, 3, and 2. Every patient was diagnosed as having refractory paradoxical MTLE. The neurological function examinations (cranial nerve, motor and sensory nerve, coordination movement, and gait) were normal for these four cases.
Preoperative evaluation and CAH
The duration of the medical history was greater than 2 years and the seizure frequency was greater than 12 times per year in every case. The four cases had typical symptoms of MTLE at the beginning of the seizures, such as oral and limb automatism. The preoperative noninvasive examination included a head magnetic resonance imaging (MRI) (including a coronary flair sequence), ictal EEG (at least three times habitual seizures) and brain PET-CT.
From July 2006 to July 2011, we examined 37 patients with refractory paradoxical MTLE. Lateralization was difficult to determine using noninvasive examinations and semiology. These 37 cases underwent bilateral intracranial electrode implantation through key-holes in the bilateral temporal areas. Five cases were shown to be BMTLE through ictal intracranial EEG. Of these, four cases underwent CAH on the side with more seizures according to the intracranial EEG results, and one case did not undergo CAH due to the same frequency of seizures on both sides. Four cases had typical temporal automatism. The head MRI showed asymmetric hippocampal structural abnormalities in these four cases, and their brain PET-CT results showed asymmetric metabolism decreases in both temporal lobes.
The four patients underwent bilateral temporal intracranial electrode implantation. Intracranial electrodes were implanted through key-holes (bone hole diameter of 1.5 cm, scalp incision of 5 cm) in the bilateral middle temporal areas. Four channel deep intracranial electrodes pointing to the hippocampus and amygdala were implanted using stereotactic techniques. Four channel strip electrodes were implanted to the anterior temporal, middle temporal, subtemporal, and posterior temporal areas. The CAH involved resections of the anterior temporal lobe (≤4.5 cm on the predominant side, ≤5 cm on the nonpredominant side), hippocampus, and amygdala.
The four patients were asked to come to the hospital at 6 months, 1 year, and 2 years after the CAH, and the postoperative seizure frequency was recorded at these time points. Some patients were followed even longer by telephone. The clinical memory test and postoperative 4-hour video EEG were conducted at 6 months, 1 year, and 2 years. The clinical memory test used the clinical memory scale (Chinese version, simplified and revised Wechsler memory scale), which has been frequently used in psychiatry and psychology in China. The memory quotient assessment used the score from the clinical memory test (corrected for age and intelligence). The preoperative intelligence test and clinical memory test were conducted in all paradoxical MTLE patients.
The clinical seizure times, side of origination in the intracranial EEG, seizure frequency, and memory quotients are shown in
This exploration of the surgical results after CAH to treat BMTLE patients is a pioneer study and has clinical importance. Paradoxical MTLE is usually shown to be unilateral MTLE through bilateral intracranial electrode implantation.[
We had too few patients (4 cases) to analyze the data using statistical methods. We only analyzed the percentage change in the average values of the seizure frequency and memory quotient. Although some data were lost [
Based on the results of this study, we demonstrated that CAH reduced the seizure frequency of the patients at different follow-up times and that CAH did not lead to neurological function deficits. Although no patient was seizure-free, the CAH had long-term therapeutic effects in seizure control for all of these BMTLE patients. The postoperative seizure frequency at the different follow-up times was approximately the same, which indicated that we could observe the treatment effect at 6 months after CAH and that the effect would not change over time (up to 5 years after the procedure, in some cases).
The seizure intensity was reduced after CAH in every patient. However, the reason for this change was unknown but may be related to a disruption of the possible synergetic enhancement in MBTLE seizures.
Although the CAH had good effects with respect to decreasing the postoperative seizure frequency and improving the ictal intensity relief for these BMTLE patients, this procedure also caused mild memory function damage over a long-term period. The postoperative average memory quotients at different times were lower than the preoperative values. The average values of the postoperative memory quotient (73.7, 77.3, and 73) at different postoperative times were approximately the same, which indicated that we could determine the memory function damage at 6 months after CAH and that the damage would not change over time. Because the temporal lobe and hippocampus are responsible for memory function,[
The preoperative interictal EEGs showed bilateral sphenoid electrodes and anterior middle and posterior temporal area discharges in every case. Moreover, the ictal discharges and intracranial EEGs showed a bilateral origination. The postoperative EEGs showed that operation contralateral interictal discharges were approximately the same as the preoperative discharges in every case and that there were epileptic discharges from the middle and posterior temporal areas on the side of the operation. The postoperative EEG findings did not change over time.
There is no doubt that CAH can reduce seizure frequency and relieve seizure intensity for BMTLE patients. However, no patient in this study was seizure-free, and every case experienced mild hypomnesis. CAH on the side in which more seizures originate for BMTLE should be very cautiously performed and is not universally recommended. If the seizure frequency has no side predominance and the patient cares strongly about memory function, we do not recommend CAH. Rather, bilateral hippocampus electric stimulation should be recommended for these patients.[
National Key Basic Research Program of China (973 Program) (2012CB720704), Capital Medical Development Found (2009-3048), and Tsinghua University Science Program (2011THZ01).
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