Yongjie Li

A retrospective study comparing preoperative evaluations and postoperative outcomes in paediatric and adult patients undergoing surgical resection for refractory epilepsy

PURPOSE To review and compare the preoperative characteristics and postsurgical outcomes in paediatric and adult patients who underwent surgical resections from 2001 to 2009. METHODS Combined data from noninvasive measures such as ictal semiology, interictal/ictal scalp EEGs, MRI and SPECT were utilised to identify the epileptogenic zones (EZ). When noninvasive investigations produced inconclusive or inconsistent findings, patients underwent intracranial EEG monitoring. Resective micro-surgical procedures were conducted according to the results of the anatomo-electro-clinical investigations and were carried out to remove the EZ. We then followed up 222 paediatric (≤18 years old) and 100 adult patients (≥19 years old) for 1-9 years postoperatively. RESULTS The mean age of seizure onset in paediatric group was significantly lower than that in adult group. 95 (43%) of the paediatric and 42 (42%) of the adult patients required long-term intracranial EEG recording. 54 (24.3%) of the paediatric and 62 (62%) of the adult patients were found to have temporal lobe epilepsy (TLE), while 149 (67.1%) of the paediatric and 37 (37.0%) of the adult patients had extra-temporal lobe epilepsy (ETLE) (p=0.000). 19 (8.6%) of the paediatric patients and 1 (1%) adult patient had hemispheric lesions (p=0.009). 148 (66.7%) of the paediatric and 61 (61.0%) of the adult patients were seizure-free during the follow-up period. 17 of 19 (89.5%) children who underwent hemispherectomy were seizure-free. In both paediatric and adult groups, the surgical outcome for patients with TLE was significantly better than that of patients with ETLE (p=0.018 in children, p=0.029 in adults). Both the location of EZs and seizure-free ratio were significantly different (p<0.001) between the preadolescent (≤12 years old) and adolescent (13-18 years old) group. Hippocampal sclerosis was the most common pathologic finding in patients with TLE in both groups, and was followed by focal cortical dysplasia. In patients with TLE, the proportion of tumour was significantly higher in the paediatric than the adult group (25.9% vs. 10%, p=0.021). CONCLUSION Paediatric patients with refractory seizures had more extratemporal or hemispheric resectable epileptogenic foci and fewer temporal foci than adults. Our study demonstrates that resective surgery is an effective and safe early intervention in strictly selected paediatric patients with refractory epilepsy.

Posterior cortex epilepsy: Diagnostic considerations and surgical outcome

PURPOSE To assess the role of various pre-surgical evaluations in posterior cortex epilepsy (PCE) and its surgical outcome. METHODS A retrospective analysis of clinical and laboratory data from 43 PCE patients referred for surgery was performed. The diagnosis was established by standard pre-surgical evaluation modalities including semiology, MRI, interictal and ictal scalp video-EEG as well as additional intracranial EEG monitoring in selected cases. RESULTS The 43 patients included 11 parietal lobe epilepsies, 13 occipital lobe epilepsies, and 19 patients with seizures originating from parieto-occipito-posterior temporal cortex. Thirty-three (76.7%) patients experienced at least one type of aura. Seventeen patients showed complex focal seizures, which were followed by secondarily generalized tonic-clonic seizures in seven of them; eighteen patients predominantly showed simple motor seizures (clonic seizures in 6, tonic seizures in 7, and versive seizures in 5). Long-term visual field deficits were observed in 8 patients. Other transient neurological deficits occurred in 7 patients. All patients received the follow-up study lasting 1-5 years, and achieved Engels I in 26 cases, II in 5, III in 5, and IV-V in 7. Malformation of cortical development was diagnosed in 41.9% of our surgical population. No significant relationship was found between the diagnostic accuracy of any pre-surgical evaluating modality and surgical outcome in this series. CONCLUSIONS Surgical treatment is effective for PCE. Accurate localization of epileptogenic zone and eloquent cortex are two key factors for favorable outcome. None of the diagnostic modalities shows obvious predictive value for favorable surgical outcome.

Surgical treatment for epilepsy involving language cortices: A combined process of electrical cortical stimulation mapping and intra-operative continuous language assessment

OBJECTIVE The purpose of this study was to improve the surgical treatment of epilepsy by maximising seizure control while protecting language function. METHODS A combined process of extra-operative electrical cortical stimulation (ECS) mapping, direct ECS and intra-operative continuous language assessment was performed during complicated operative cases. Of the 24 epilepsy patients, nine had a complex relationship between the seizure onset zone and the language cortices. The combined process was used in these nine patients. In the other 15 patients, surgical resection was completed based on extra-operative ECS results alone. Evaluations were performed before and after surgery to assess language function and seizure control. RESULTS The intra-operative continuous language assessment provided important information at the time of the resection. Seven extra-operative ECS positive language sites were resected without obvious language deficits in two patients. Resection was interrupted by language disturbances in an area where no extra-operative ECS positive site was identified in one patient. In three other patients, functional boundary was undefined in extra-operative ECS result, epileptogenic cortices were maximally resected during the continuous language assessment. In terms of seizure control, 18 of 24 (75%) patients reached Engels class I, including all nine patients who underwent intra-operative continuous language assessment. One patient had minor surgery-related language deficits three months after resection. CONCLUSIONS Intra-operative continuous language assessment proved to be complementary to extra-operative ECS mappings. The combination of ECS mappings and intra-operative continuous language assessment can maximise the resection of epileptogenic cortices and preserve language function in difficult cases involving the language cortex.

Assessment of Age-Related Morphometric Changes of Subcortical Structures in Healthy People Using Ultra-High Field 7 Tesla Magnetic Resonance Imaging

Objective: To assess the age-related morphometric changes of subcortical structures in healthy people. Materials and Methods: Ultra-high field 7 tesla magnetic resonance (MR) imaging in humans was used to visualize the subcortical structures of healthy young, middle-aged and elderly participants. Using the magnetization-prepared two rapid acquisition gradient echo (MP2RAGE) sequence, we assessed the visibility of the margins of the thalamus and white matter in the thalamus, as well as the anterior commissure (AC) and posterior commissure (PC) length, the maximal height of the thalamus, the half width of the third ventricle and the distance between the AC and the center of the mammillothalamic tract (MTT) at the level of the AC-PC plane. All quantitative data were statistically evaluated. Results: The AC-PC length did not differ significantly among the three groups. The maximal height of the thalamus decreased with age (rs(53) = −0.719, p < 0.001). The half width of the third ventricle (rs(53) = 0.705, p < 0.001) and the distance between the AC and the center of the MTT (rs(53) = 0.485, p < 0.001) increased with age. The distance between the AC and the center of the MTT of the young and the elderly participants differed significantly (p = 0.007). Conclusion: The AC-PC length is not a good candidate for proportional correction during atlas-to-patient registration. The maximal height of the thalamus and the half width of the third ventricle correlated strongly with age, and the MTT position in relation to the AC shifted posteriorly as age increased. These age-related morphometric changes of subcortical structures should be considered in targeting for functional neurosurgery.

Surgical treatment of hypermotor seizures originating from the temporal lobe

PURPOSE To describe the characteristics of electroclinical manifestations in patients with hypermotor seizures (HMSs) originating from the temporal lobe. METHODS We retrospectively reviewed the data of patients who underwent surgical treatments for seizure to identify patients with HMSs of temporal origin. We systematically reviewed patient seizure histories, imaging reports, video-EEG monitoring data, operative records and pathological findings. RESULTS Eight of the 9 patients reported auras. The ictal behavior included marked agitation in 5 patients and mild agitation in 4 patients. All of the 9 patients exhibited stiffness or dystonia of the upper limb or contralateral limbs during ictus. Seven of the 9 patients completed intracranial recording and at least 3 seizures were recorded for each patient. The intracranial recordings showed ictal activity originating from mesial temporal lobe in 6 patients and the lateral temporal lobe in 1 patient. The time interval of ictal propagation from the temporal to frontal lobe was 15.0 ± 8.3 s. While the time interval from EEG origination to the beginning of hypermotor behavior was 21.0 ± 8.1 s. Brain MRIs revealed hippocampal sclerosis in 3, neoplastic lesion in 1, and normal images in the remaining 5 patients. Patients were followed for 1-5 years after the anterior temporal lobectomy; 7 patients remained seizure-free throughout follow-up. CONCLUSION Some HMSs can originate from the temporal lobe. In carefully selected patients, surgical resection may lead to good outcomes.

Surgical treatment for patients with symptomatic generalised seizures due to brain lesions

OBJECT To study the role of epilepsy surgery for patients with focal lesions who exhibited the semiology of clinically generalised seizures. METHODS From our epilepsy surgery series, we identified 29 patients who underwent surgery for seizures, including certain types of generalised seizures, according to their ictal semiology. We systematically reviewed the brain imaging, video-EEG, surgical operation, and pathological findings data of these patients. RESULTS All patients had at least one type of generalised seizure according to the semiology; these seizures included epileptic spasms, myoclonic seizures, tonic seizures, atonic seizures and atypical absence seizures. Eight patients had a single type of seizure, 11 patients had two types of seizures, and 10 patients had more than two types of seizures. In addition to symptomatic generalised seizures, complex partial seizures were also recorded in eight patients. In 24 patients, the ictal semiology showed slight asymmetric movements in certain types of seizures. Generalised interictal epileptic discharges were recorded in 24 patients; and generalised ictal epileptic discharges as the only EEG pattern were recorded in 13 patients. Intracranial recording was performed in 20 patients; 10 of whom showed a rhythm of fast activities at the initiation of the seizures. Functional hemispherectomy was performed for three patients with hemispheric lesions. Focal resection of the epileptogenic zone was performed in 26 patients. The resected epileptogenic zones involved a single lobe in 10 patients, two lobes in 11 patients, and three lobes in 5 patients; the parietal lobe was the most commonly involved lobe (in 19 cases). Scar lesions (in 17 patients) were most commonly observed on pathological examination. At the last follow-up (mean 18±8.3 months, range 12-48), 17 (58.6%) patients were seizure-free. CONCLUSIONS Certain patients with local brain lesions can have seizures with specific types of generalised semiology. An appropriate operation may be helpful for a portion of these patients.

High-frequency and brief-pulse stimulation pulses terminate cortical electrical stimulation-induced afterdischarges

Brief-pulse stimulation at 50 Hz has been shown to terminate afterdischarges observed in epilepsy patients. However, the optimal pulse stimulation parameters for terminating cortical electrical stimulation-induced afterdischarges remain unclear. In the present study, we examined the effects of different brief-pulse stimulation frequencies (5, 50 and 100 Hz) on cortical electrical stimulation-induced afterdischarges in 10 patients with refractory epilepsy. Results demonstrated that brief-pulse stimulation could terminate cortical electrical stimulation-induced afterdischarges in refractory epilepsy patients. In conclusion, (1) a brief-pulse stimulation was more effective when the afterdischarge did not extend to the surrounding brain area. (2) A higher brief-pulse stimulation frequency (especially 100 Hz) was more likely to terminate an afterdischarge. (3) A low current intensity of brief-pulse stimulation was more likely to terminate an afterdischarge

Properties of afterdischarges from electrical stimulation in patients with epilepsy

OBJECTIVE To investigate the properties of afterdischarges (ADs) from intracerebral electrical stimulation (ES) in patients with epilepsy who underwent stereotactic electroencephalography (SEEG) and determine the relationship between epileptogenic zone (EZ) or irritative zone (IZ) and ADs. METHODS We retrospectively analyzed 10 patients with intractable epilepsy who underwent SEEG. ESs were delivered following the given parameters: bipolar, biphasic, 50Hz, 0.2ms pulse duration, 0.5-10mA. The properties of ADs were documented, including their incidence, location, threshold, morphology and evolution. RESULTS A total of 213 ADs (5%) were elicited by 4701 trains of ES. Stimulation through contacts implanted in the hippocampus (59%) generally evoked more ADs than contacts elsewhere (19%). AD thresholds for hippocampal stimulation were significantly lower than those for stimulation in grey matter. Polyspikes (58%) were the most common AD morphology. Evolution occurred more commonly with sequential spikes (47%) than with other AD morphologies (14%). There was no significant correlation between the location of ADs and EZ. However, ADs were significantly more frequently localized to IZ than areas outside IZ (P<0.05). CONCLUSIONS There seemed to be a lack of correlation between the location of ADs and EZ. However, ADs were more likely to be elicited in IZ.

Surgical resection of epileptogenic cortical dysplasia in precentral gyrus

We present the case of a patient with epilepsy arising from cortical dysplasia in his precentral gyrus. The lesion was resected based on the results of video-ECoG (electrocorticograph) monitoring and electrical cortical stimulation. The patient has been seizure-free for 1 year since operation, and no neurological deficits have been observed. We discuss possible mechanisms of cortical reorganization in this patient and the features of focal cortical dysplasia (FCD) IIb in eloquent cortices.

Electrical stimulation of the insulo-opercular region: visual phenomena and altered body-ownership symptoms

PURPOSE Using direct intracerebral electrical stimulation (ES) in epileptic patients to evoke symptoms to help identify the functional neuroanatomy of the insular lobe and opercula. METHODS We selected 43 patients who had at least 1 electrode inserted into the insula or opercula via an oblique approach among 135 patients with intractable epilepsy. Bipolar stimulation was chosen, and the stimulation parameters of the biphasic waves included a pulse width of 0.2 ms, a frequency of 50 Hz, a duration of 3 s, and an intensity gradually increasing from 0.5 to 4 mA. RESULTS In total, 93 electrodes were implanted into the insula or insular opercula, and 169 of 281 contacts (60.1%) evoked 212 responses by ES of the insula. 142 responses were induced by stimulating the insular opercula in 126 of 343 sites (36.7%). Usual responses, such as somatosensory, visceral sensory, speech, auditory, and motor responses, were evoked. In addition, rarely reported responses, including cardiovascular symptoms (tachycardia), visual symptoms evoked by ES of the parietal and temporal opercula, and vestibular symptoms (like the loss of ownership of the body) evoked following stimulation of the posterior insula and parietal operculum, were also induced in our study. CONCLUSIONS The insula and opercula perform various and complicated functions. The posterior insula and parietal operculum could play important roles in body-ownership symptoms. The complicated visual phenomena were partially related to the temporal operculum.