Preoperative amygdala fMRI in temporal lobe epilepsy

Purpose:   Anterior temporal lobe resections (ATLR) benefit 70% of patients with refractory mesial temporal lobe epilepsy (TLE), but may be complicated by emotional disturbances. We used functional magnetic resonance imaging (fMRI) to investigate the role of the amygdala in processing emotions in TLE and whether this may be a potential preoperative predictive marker for emotional disturbances following surgery.
Methods:   We studied 54 patients with refractory mesial TLE due to hippocampal sclerosis (28 right, 26 left) and 21 healthy controls using a memory encoding fMRI paradigm, which included viewing fearful and neutral faces. Twenty-one TLE patients (10 left, 11 right) subsequently underwent ATLR. Anxiety and depression were assessed preoperatively and 4 months postoperatively using the Hospital Anxiety and Depression Scale.
Results:   On viewing fearful faces, healthy controls demonstrated left lateralized, while right TLE patients showed bilateral amygdala activation. Left TLE patients had significantly reduced activation in left and right amygdalae compared to controls and right TLE patients. In right TLE patients, left and right amygdala activation was significantly related to preoperative anxiety and depression levels, and preoperative right amygdala activation correlated significantly with postoperative change of anxiety and depression scores, characterized by greater increases in anxiety and depression in patients with greater preoperative activation. No such correlations were seen for left TLE patients.
Discussion:   The fearful face fMRI paradigm is a reliable method for visualizing amygdala activation in controls and patients with mesial TLE. Activation of the right amygdala preoperatively was predictive of emotional disturbances following right ATLR.     

颞叶癫痫手术时的皮质脑电描记

报告1980年10月至1992年6月间,在皮质脑电描记下手术治疗颞叶癫痫55例,前颞叶切除50例.杏仁核海马切除5例。皮质脑电描记结果说明颞叶癫痫的痫灶绝大多数来源于颞叶外侧皮质和颞叶内侧结构。术中皮质脑电描记可提供痫灶的精确部位和范围。     

Anesthesia for temporal lobe epilepsy surgery

Anesthetic considerations for temporal lobectomy for refractory epilepsy include ensuring a safe and comfortable perioperative experience for the patient, providing suitable operating conditions for the surgeon, avoiding interference with intraoperative electrocorticographic (ECoG) recordings and facilitating intraoperative functional cortical mapping, if performed. Providing the conditions that simultaneously meet these requirements, using general anesthesia or local anesthesia with sedation, remains a significant challenge for the neuroanesthetist. We review issues pertinent to the choice of anesthetic technique for these procedures.     

Electrocorticography in temporal lobe epilepsy surgery

The results of intra-operative cortical EEG recordings (ECoG) were assessed in 30 patients with medically refractory complex partial seizures submitted to temporal lobectomy. Interictal spiking was most frequently recorded from mesial temporal lobe structures (amygdaloid-hippocampal region) and from the temporal neocortex synchronously, as observed in 21/30 patients. In 7 patients, the interictal spiking involved the temporal neocortex exclusively. Electrical stimulation of mesial temporal lobe structures reproduced the patient's habitual warning in 10 patients. The results of this study confirms that ECoG provides reliable intra-operative mapping of the epileptogenic brain tissue to be excised.     

Mortality after temporal lobe epilepsy surgery

Purpose: To report mortality, after a longer interval, in a cohort of patients with drug‐resistant epilepsy treated by temporal lobe surgery between 1975 and 1995. A previous audit of these patients ending December 1, 1997 observed a standardized mortality ratio (SMR) of 4.5. Methods: We analyzed mortality in a cohort of 306 patients with temporal lobe epilepsy (TLE) who underwent temporal lobe resections between December 1, 1975 and December 1, 1995. Deaths occurring after December 1,1997 and until December 1, 2009 were evaluated. Medical records, death certificates, postmortem examination reports, coroner officer’s reports, and coroner’s inquest reports were sought, and causes of death were ascertained. Sudden unexpected death in epilepsy (SUDEP) cases were identified. Key Findings: In 3,569 person‐years of follow‐up 19 deaths occurred, [SMR 2.00, 95% confidence interval (CI) 1.27–3.13], 14 men (SMR 2.01, 95% CI 1.19–3.39) and 5 women (SMR 1.68, 95% CI 0.70–4.03). On analysis of subgroups, SMRs were significantly elevated in patients with mesial temporal sclerosis (MTS) (SMR 2.50, 95% CI 1.38–4.51), men with MTS (SMR 3.12, 95% CI 1.56–6.25), men with nonspecific lesions (SMR 2.68, 95% CI 1.00–7.09), and right‐sided resections in MTS (SMR 3.33, 95% CI 1.39–8.00). During follow‐up, six SUDEP cases were observed with a rate of 1/595 person‐years. Significance: In this cohort, the risk for premature death in patients undergoing TLE surgery decreased over time but remained above the standard population. Men had a slightly higher risk than women, as did right‐sided resections in MTS, confirming this observation in the original cohort. Although lower, the risk of SUDEP remained. Without up‐to‐date information on seizure outcome, we were unable to directly relate this to mortality.     

Stereotactic surgery for temporal lobe epilepsy

In light of the recent resurgence of interest in stereotactic functional procedures, the authors have reviewed the role of stereotactic ablative surgery in the treatment of temporal lobe epilepsy. Literature pertaining to stereotactic amygdalotomy, hippocampotomy and fornicotomy is reviewed and summarized. However, the results presented in those early studies are difficult to interpret given the surgical techniques and outcome assessment used. Modern stereotactic ablative surgery using current image-guided technology offers the opportunity to revisit some of these techniques. In recent studies of stereotactic amygdalohippocampotomy, outcomes are not as favorable as those obtained with standard temporal resections. However, these relatively discrete ablative techniques may shed light on the anatomical substrate underlying temporal lobe epilepsy.     

Depression in temporal lobe epilepsy before epilepsy surgery

PURPOSE: This study examined the association of depression with laterality of epilepsy surgery in patients with temporal lobe epilepsy before standard lobectomy. METHODS: Forty-nine patients presented for EEG telemetry for localization of epilepsy and eventual temporal lobectomy. Patients underwent routine neuropsychiatric evaluation blinded for epileptic focus, including ratings on depression. Patients were grouped according to right (n = 25, M = 10/F = 15) and left (n = 24, M = 13/F = 11) temporal lobectomy. Analysis of variance included side of surgery as grouping variable and sex, general depressive, cognitive depressive, and vegetative depressive symptoms as dependent variables. Chi2 analyses included categoric variables of sex, handedness, education, neuropathologic findings, and current affective disorders. t Tests were performed on variables of age, epilepsy duration, and cognitive function. RESULTS: Right and left temporal epilepsy groups did not differ with regard to sex, handedness, age, duration of epilepsy, education, cognitive function, and neuropathology. Patients with right temporal epilepsy rated higher on general, cognitive. and vegetative depression scores. Women scored higher on general, cognitive, and vegetative depression scores. Current affective disorders were more common in the right temporal epilepsy group. CONCLUSIONS: Depression ratings and diagnoses were more prominent in patients with right temporal lobe epilepsy and in women in particular. The strength of this laterality finding lies in the selection of patients, as all underwent epilepsy surgery. The finding on gender difference partly reflects the higher incidence of depression in women and needs further exploration. The laterality finding contrasts with recent findings in epilepsy, stroke, and trauma that associate depression with left hemispheric lesions. However, our results are consistent with findings in electrically hyperactive lesions such as gelastic and dacrystic epilepsy.     

Isolated amygdala enlargement in temporal lobe epilepsy: A systematic review

ObjectiveThe objective of this study was to compare the seizure characteristics and treatment outcomes in patient groups with temporal lobe epilepsy (TLE) identified with isolated amygdala enlargement (AE) on magnetic resonance imaging studies.MethodsPubMed, Embase, and the Cochrane Library were searched for relevant studies using the keywords ‘amygdala enlargement’, ‘epilepsy’, and ‘seizures’ in April 2015. Human studies, written in English, that investigated cohorts of patients with TLE and AE were included.ResultsOf 204 abstracts initially identified using the search strategy, 14 studies met the inclusion criteria (11 epilepsy studies and 3 psychiatry studies). Ultimately, 8 full studies on AE and TLE involving 107 unique patients were analyzed. Gender distribution consisted of 50 males and 57 females. Right amygdala enlargement was seen in 39 patients, left enlargement in 58 patients, and bilateral enlargement in 7 patients. Surgical resection was performed in 28 patients, with the most common finding being dysplasia/hamartoma or focal cortical dysplasia. Most studies involved small samples of less than 12 patients. There was a wide discrepancy in the methods used to measure amygdala volume, in both patients and controls, hindering comparisons. Most TLE with AE studies observed a later age of seizure onset (mean: 32.2 years) compared with studies involving TLE with HS (mean of mid- to late childhood). A higher frequency of complex partial seizures compared with that of convulsive seizures is seen in patients with AE (67–100% vs. 26–47%), and they have an excellent response to antiepileptic drugs (81.8%–100% of seizure-free patients). All studies that included controls also found a significant difference in frequency of seizure types between their cases and controls.ConclusionsReliable assessment of amygdala volume remains a critical issue hindering better understanding of the clinical management and research of this focal epilepsy syndrome. Within these limitations, the literature suggests characteristics of an older age of epilepsy onset, a greater tendency to nonconvulsive seizures, and a good response to antiepileptic drugs in this interesting group of epilepsies.     

The duration of temporal lobe epilepsy and seizure outcome after epilepsy surgery

To assess the effect of the duration of epilepsy on the outcome of epilepsy surgery in non-lesional medically refractory temporal lobe epilepsy we reviewed the outcome of 76 patients.MethodsAll patients had anterior temporal resections for “non-lesional” temporal epilepsy (excluding any patient with tumours or vascular malformations but including patients with hippocampal sclerosis). Outcome at one year was assessed using Engel's scale.Results67% had a good outcome (Engel I or II). The mean duration of epilepsy was 23.0 years (range 2.9–46.9 years). Overall, there was no significant difference between patients with good outcome (mean duration 22.4 years) and poor outcome (mean duration 24.2 years) (p = 0.49). The proportion of patients with good outcome was slightly higher in the shorter duration groups. (Duration less than 10 years 75%, 10–19 years 71%, 20–29 years 65%, 30–39 years 62%, and 40–49 years 60% good outcome, p = 0.95).ConclusionWe found no significant associations between outcome and duration of epilepsy.     

Cellular pathology of amygdala neurons in human temporal lobe epilepsy

The amygdala complex substantially contributes to the generation and propagation of focal seizures in patients suffering from temporal lobe epilepsy (TLE). A cellular substrate for increased excitability in the human amygdala, however, remains to be identified. Here, we analyzed the three-dimensional morphology of 264 neurons from different subregions of the amygdaloid complex obtained from 17 "en bloc" resected surgical specimens using intracellular Lucifer Yellow (LY) injection and confocal laser scanning microscopy. Autopsy samples from unaffected individuals ( n=3, 20 neurons) served as controls. We have identified spine-laden, spine-sparse and aspinous cells in the lateral, basal, accessory basal and granular nuclei. Semiquantitative analysis points to significant changes in neuronal soma size, number of dendrites and spine densities in specimens from epilepsy patients compared to controls. Neuronal somata in the epilepsy group were smaller compared to controls ( P<0.01), neurons had fewer first-order dendrites ( P<0.01), whereas the maximum density of spines per dendritic segment in these cells was increased in TLE patients ( P<0.01). There were also dendritic alterations such as focal constrictions or spine bifurcations. These changes were consistent between amygdaloid subregions. The dendritic morphology of amygdaloid neurons in TLE patients points to substantial changes in synaptic connectivity and would be compatible with altered neuronal circuitries operating in the epileptic human amygdala. Although the morphological alterations differ from those described in hippocampal subregions of a similar cohort of TLE patients, they appear to reflect a characteristic pathological substrate associated with seizure activity/propagation within the amygdaloid complex.     

Recognition of emotion with temporal lobe epilepsy and asymmetrical amygdala damage

PURPOSE: Impairments in emotion recognition occur when there is bilateral damage to the amygdala. In this study, ability to recognize auditory and visual expressions of emotion was investigated in people with asymmetrical amygdala damage (AAD) and temporal lobe epilepsy (TLE). METHODS: Recognition of five emotions was tested across three participant groups: those with right AAD and TLE, those with left AAD and TLE, and a comparison group. Four tasks were administered: recognition of emotion from facial expressions, sentences describing emotion-laden situations, nonverbal sounds, and prosody. RESULTS: Accuracy scores for each task and emotion were analysed, and no consistent overall effect of AAD on emotion recognition was found. However, some individual participants with AAD were significantly impaired at recognizing emotions, in both auditory and visual domains. CONCLUSIONS: The findings indicate that a minority of individuals with AAD have impairments in emotion recognition, but no evidence of specific impairments (e.g., visual or auditory) was found.     

Neuropsychological assessment for temporal lobe epilepsy surgery

Neuropsychological assessment consists of a comprehensive evaluation of cognitive functioning and most often some evaluation of motor skills and sensory status also. Cognitive functions sampled typically include "intelligence" (IQ tests), attention, language skills, visuospatial abilities, "executive skills" and other abilities associated with frontal-lobe function, and learning and memory. Thus, the assessment samples vary widely among a variety of functions, providing a comprehensive picture of an individual's strengths and weaknesses. The resulting pattern points to the probable site of epileptic focus. Neuropsychological findings also serve to predict the risk for postsurgical cognitive decline and, when performance before and after operation is compared, they provide data on the impact of surgery upon cognitive functioning. Comprehensive evaluation of learning and memory is particularly important in this context, because of the frequency of temporal lobe epilepsy and the prominence of memory dysfunction associated with it. In addition, patients slated for elective surgery may also undergo an intracarotid amobarbital procedure (IAP), which is performed to determine the side of cerebral dominance for language and to test the memory capabilities of each hemisphere alone. All of these specialized neuropsychological tools are discussed in this paper.     

Pediatric candidates for temporal lobe epilepsy surgery

Temporal lobectomy is an under-valued and effective therapy for selected children with temporal lobe seizures. This article details three components of the identification and evaluation of such children. The ictal symptoms and signs remains an essential component. This includes an aura suggesting limbic system involvement, and the nature of automatisms and other motor phenomena which may have lateralising value. Electroencephalography continues to accurately identify a principally epileptogenic focus in children and adults. The value of high quality magnetic resonance imaging is emphasized. Invasive studies are required in only a minority of cases. Several studies have revealed that 73-100% of carefully selected children receive benefit from this procedure whereas significant neurosurgical complications rarely occur.     

Intraoperative electrocorticography in temporal lobe epilepsy surgery

Although in clinical use for many years, the validity of intraoperative electrocorticography (ECoG) in guiding resective temporal lobe epilepsy (TLE) surgery is uncertain. Advances in neuroimaging and extraoperative intracranial recordings have contributed greatly to the identification of epileptogenic lesions and cortex, clarifying the limitations of a brief intraoperative interictal recording. Studies of undifferentiated ECoG findings (which classify all interictal cortical spike discharges as equal) tend to not support this method. This article reviews ECoG and presents data from 86 TLE surgeries at the University of British Columbia suggesting that differentiation of ECoG features may enhance the contribution of this time honored method. Specifically, independent foci may be more important for epileptogenesis than synchronous foci, and postexcision activation appears to be a benign phenomenon, while residual spikes unaltered by the resection correlate with a greater proportion of seizure recurrence.     

Scalp EEG in temporal lobe epilepsy surgery

Electroencephalography (EEG) with standard scalp and additional noninvasive electrodes plays a major role in the selection of patients for temporal lobe epilepsy surgery. Recent studies have provided data supporting the value of interictal and postictal EEG in assessing the site of ictal onset. Scalp ictal rhythms are morphologically complex but at least one pattern (a five cycles/second rhythm maximum at the sphenoidal or anterior temporal electrode) occurs in >50% of patients and has a high predictive value and interobserver reliability for temporal lobe originating seizures. Thorough interictal and ictal scalp EEG evaluation, in conjunction with modern neuroimaging, is sufficient for proceeding to surgery without invasive recordings in some patients. Further studies are required to define the scalp ictal characteristics of mesial vs. lateral temporal lobe epilepsy.     

Sleep before and after temporal lobe epilepsy surgery

PurposePatients with epilepsy often complain of non-restorative sleep. This is the consequence of the acute effect of seizures and the chronic effect of epilepsy responsible for disrupting sleep architecture. Other factors such as antiepileptic drugs (AEDs), also play a role in the alteration of sleep organization. The aim of this study was to evaluate the specific effect of seizures and interictal epileptiform abnormalities (IEAs) on sleep, in particular to see whether reducing seizure frequency by epilepsy surgery might improve sleep organization in these patients.MethodsEleven patients with refractory mesial temporal lobe epilepsy, who underwent surgical treatment and who were seizure free at the follow-up, were included in the study. Treatment with AEDs was not significantly modified before the second year of follow-up. Patients were evaluated before surgery, at 1-year and 2-year follow-up visits with a videoEEG monitoring (24 h/24). At each follow-up visit, interictal epileptiform abnormalities and sleep macrostructure parameters were assessed.ResultsAll patients showed a reduction of their IEAs. At 1-year follow-up, total sleep time and REM sleep increased significantly (p = 0.032 and p = 0.006, respectively). At 2-year follow-up, an important increase of REM sleep was observed (p = 0.028). Most significant variations were noted 1 year after surgery. No significant variations were observed between the first and the second year after surgery.ConclusionsSurgical treatment of temporal lobe epilepsy may improve sleep macrostructure by reducing the number of seizures and of IEAs. These results indirectly confirm the role of epilepsy in disrupting sleep organization chronically.