Seizure's outcome after cortical resections including the face and tongue rolandic areas in patients with refractory epilepsy and normal MRI submitted to subdural grids' implantation

Surgical approaches to refractory central lobule epilepsy: a systematic review on the role of resection, ablation, and stimulation in the contemporary era

OBJECTIVE

Epilepsy originating from the central lobule (i.e., the primary sensorimotor cortex) is a challenging entity to treat given its involvement of eloquent cortex. The objective of this study was to review available evidence on treatment options for central lobule epilepsy.

METHODS

A comprehensive literature search (PubMed/Medline, EMBASE, and Scopus) was conducted for studies (1990 to date) investigating postoperative outcomes for central lobule epilepsy. The primary and secondary endpoints were seizure freedom at last follow-up and postoperative neurological deficit, respectively. The following procedures were included: open resection, multiple subpial transections (MSTs), laser and radiofrequency ablation, deep brain stimulation (DBS), responsive neurostimulation (RNS), and continuous subthreshold cortical stimulation (CSCS).

RESULTS

A total of 52 studies and 504 patients were analyzed. Most evidence was based on open resection, yielding a total of 400 patients (24 studies), of whom 62% achieved seizure freedom at a mean follow-up of 48 months. A new or worsened motor deficit occurred in 44% (permanent in 19%). Forty-six patients underwent MSTs, of whom 16% achieved seizure freedom and 30% had a neurological deficit (permanent in 12%). There were 6 laser ablation cases (cavernomas in 50%) with seizure freedom in 4 patients and 1 patient with temporary motor deficit. There were 5 radiofrequency ablation cases, with 1 patient achieving seizure freedom, 2 patients each with Engel class III and IV outcomes, and 2 patients with motor deficit. The mean seizure frequency reduction at the last follow-up was 79% for RNS (28 patients), 90% for CSCS (15 patients), and 73% for DBS (4 patients). There were no cases of temporary or permanent neurological deficit in the CSCS or DBS group.

CONCLUSIONS

This review highlights the safety and efficacy profile of resection, ablation, and stimulation for refractory central lobe epilepsy. Resection of localized regions of epilepsy onset zones results in good rates of seizure freedom (62%); however, nearly 20% of patients had permanent motor deficits. The authors hope that this review will be useful to providers and patients when tailoring decision-making for this intricate pathology.

Functional cortical localization of tongue movements using corticokinematic coherence with a deep learning-assisted motion capture system

Corticokinematic coherence (CKC) between magnetoencephalographic and movement signals using an accelerometer is useful for the functional localization of the primary sensorimotor cortex (SM1). However, it is difficult to determine the tongue CKC because an accelerometer yields excessive magnetic artifacts. Here, we introduce a novel approach for measuring the tongue CKC using a deep learning-assisted motion capture system with videography, and compare it with an accelerometer in a control task measuring finger movement. Twelve healthy volunteers performed rhythmical side-to-side tongue movements in the whole-head magnetoencephalographic system, which were simultaneously recorded using a video camera and examined using a deep learning-assisted motion capture system. In the control task, right finger CKC measurements were simultaneously evaluated via motion capture and an accelerometer. The right finger CKC with motion capture was significant at the movement frequency peaks or its harmonics over the contralateral hemisphere; the motion-captured CKC was 84.9% similar to that with the accelerometer. The tongue CKC was significant at the movement frequency peaks or its harmonics over both hemispheres. The CKC sources of the tongue were considerably lateral and inferior to those of the finger. Thus, the CKC with deep learning-assisted motion capture can evaluate the functional localization of the tongue SM1.

Neuropsychological Function and Quality of Life after Resection of Suspected Lower-Grade Glioma in the Face Primary Motor Area

The negative side effects of neurosurgical resection of the lower third of the primary motor cortex (M1) are often described as relatively mild. However, detailed descriptions of how these resections affect neurocognitive function, speech, mental health and quality of life (QoL) are sparse. In the present study, seven patients with suspected lower-grade glioma (WHO II-III) in the inferior M1 were assessed for facial motor function, cognitive function, anxiety and QoL before and after awake surgical resections. The main finding was that after surgery, six of the seven patients experienced a mild facial motor dysfunction, mainly affecting the mouth, tongue and throat. At the group level, we were also able to observe a significant postoperative decline in maximum verbal speed, whereas no negative effects on measures of word production (i.e., verbal fluency) were seen. Self-reported QoL data suggest that some patients experienced increased social isolation postoperatively but do not lend support to the interpretation that this was caused by direct neurological side effects of the surgery. The results appear to support the general notion that awake surgery in the lower M1 can be performed safely and with postoperative deficits that are most often perceived by the patient as tolerable.

Surgery for epilepsy in the primary motor cortex: A critical review

Surgical resection of the epileptogenic zone within the frontal lobe can be a very effective treatment for medically refractory epilepsy originating from this area. While much of the frontal lobe consists of highly eloquent tissue, surgery is not necessarily contraindicated as long as the epileptogenic zone is well-localized and the tissue resected is limited. Resection of the primary motor cortex was described by Victor Horsley in the 19th century and was used frequently in the early 20th century for a variety of neurological disorders including epilepsy; improvements in surgical techniques and mapping has led to a resurgence of its use in the past few decades. Although many surgeons are hesitant to resect tissue adjacent to the primary hand area based on fears of new motor deficits, there is extensive evidence that focal resections are well-tolerated over the long-term with residual weakness that is fairly mild: some patients experience postoperative weakness, including hemiparesis, but a stereotypical recovery of strength from proximal to distal muscles occurs over months, and only one quarter will have a permanent neurologic deficit, usually consisting of difficulty with fine motor movements. The main alternative to surgical resection is subpial transection, characterized by a small decrease in postoperative deficits and significantly worse seizure outcomes. The treatment of patients with seizures originating from this region requires a solid understanding of the structural and functional anatomy of the frontal lobe.

Central lobe epilepsy surgery - (functional) results and how to evaluate them

OBJECT

To evaluate whether central lobe epilepsy (CLE) surgery in the pericentral area implies inevitable function loss and to determine how postsurgical functional outcomes are perceived by the patient.

METHODS

We included all 22 people with epilepsy (PWE) who received central lobe epilepsy (CLE) surgery in the pre- and postcentral gyri between 1995 and 2015 in the University Medical Center Utrecht. We determined function loss and followed-up on quality of life (AQoL-8D), mobility (Rivermead Mobility Index RMI) and self-evaluation of the surgery. To compare this with the literature, a systematic review was conducted, with specific regard for studies that included functional outcome.

RESULTS

Our own cohort showed newly developed functional loss in 54.4% postoperatively. Follow-up questionnaires were returned by 11/19 PWE (the other 3 could not be contacted). The mean AQoL-8d score was 0.74 (SD 0.16) and the mean RMI score was 13.7 (SD 3.0). This mean AQoL-8d was slightly lower than the Western mean population scores (0.86 and 0.87 respectively). RMI scores and postoperative functional deficits were both significantly related to how well PWE scored on the AQoL-8d. 72.7% of the PWE became seizure free after surgery (Engel class 1A). All PWE were happy with the CLE surgery and would recommend this type of surgery to other PWE. Becoming seizure-free, gaining better functioning and having more energy were reported as the most important reasons. The literature provided 475 unique papers, of which 25 were selected for critical appraisal. Six studies were of adequate quality and provided sufficient information to extract results. Prevalence of postoperative neurological deficit varied between 0 and 50%. No information is given on patient's perceptions.

CONCLUSIONS

About half of central lobe resections do not result in new neurological deficits. The patient's perspective is important in CLE surgery, but neglected in the literature. PWE may report being satisfied with the results of surgery despite new deficits and impact on quality of life. Counseling in CLE surgery should take these findings into account. Neurologists and neurosurgeons should not by default refrain from CLE surgery and think a PWE will not accept a deficit.

Functional differences among stimulation-identified cortical naming sites in the temporal region

To preserve postoperative language, electrical stimulation mapping is often conducted prior to surgery involving the language-dominant hemisphere. Object naming is the task most widely used to identify language cortex, and sites where stimulation elicits naming difficulty are typically spared from resection. In clinical practice, sites classified as positive undergo no further testing regarding the underlying cause of naming failure. Word production is a complex function involving multiple mechanisms that culminate in the identification of the target word. Two main mechanisms, i.e., semantic and phonological, underlie the retrieval of stored information regarding word meaning and word sounds, and naming can be hampered by disrupting either of these. These two mechanisms are likely mediated by different brain areas, and therefore, stimulation-identified naming sites might not be functionally equivalent. We investigated whether further testing at stimulation-identified naming sites would reveal an anatomical dissociation between these two mechanisms. In 16 patients with refractory temporal lobe epilepsy (TLE) with implanted subdural electrodes, we tested whether, despite inability to produce an item name, patients could reliably access semantic or phonological information regarding objects during cortical stimulation. We found that stimulation at naming sites in superior temporal cortex tended to impair phonological processing yet spared access to semantic information. By contrast, stimulation of inferior temporal naming sites revealed a greater proportion of sites where semantic access was impaired and a dissociation between sites where stimulation spared or disrupted semantic or phonological processing. These functional-anatomical dissociations reveal the more specific contribution to naming provided by these cortical areas and shed light on the often profound, interictal word-finding deficit observed in temporal lobe epilepsy. Additionally, these techniques potentially lay the groundwork for future studies to determine whether particular naming sites that fall within the margins of the desired clinical resection might be resected without significant risk of decline.

Placement of subdural grids in pediatric patients: technique and results

PURPOSE

The purpose of this study is to describe common indications and technique for the application of chronic invasive electrodes in the pediatric patient suffering from medically intractable epilepsy.

METHODS

This chapter was prepared based on a retrospective review of the literature and personal experience based from a large tertiary epilepsy center.

CONCLUSIONS

Invasive subdural recordings are a safe and efficacious tool to identify the epileptogenic zone and its relationship to functional cortex in highly selected patients with medically refractory epilepsy. The ability to localize the EZ approaches 90 to 100 %, but seizure-free outcome is more complex depending greatly on the experience of the surgical team and the extent of resection.

Surgery for perirolandic epilepsy: Epileptogenic cortex resection guided by chronic intracranial electroencephalography and electric cortical stimulation mapping

SUBJECT

The objective of this study was to assess outcome with regard to seizure status and neurological function in patients undergoing resective surgery involving the perirolandic area.

METHOD

All 15 patients who underwent perirolandic cortical resection between October 2006 and September 2007 at the Comprehensive Epilepsy Centre of Beijing Xuanwu Hospital were included in the study. The locations of functional cortical areas, ictal onset zones and epileptogenic lesions were mapped by chronic intracranial EEG recordings and electric cortical stimulation. Seizure outcome was determined using the modified classification of Engel and colleagues. Motor and sensory deficits were monitored.

RESULTS

At last follow-up 5 patients (33%) were in Engel class I, 4 (27%) were in class II, 3 (20%) were in class III, and 3 (20%) were in class IV. Nine patients suffered immediate functional deficits; 8 of these recovered completely within 2 weeks to 3 months of surgery. One had mild persistent loss of finger motor control.

CONCLUSION

After accurate presurgical evaluation using invasive recordings and functional brain mapping, epileptogenic cortical resection can give excellent results and few deficits in patients with perirolandic epilepsy.

Neurosurgical management of intractable rolandic epilepsy in children: role of resection in eloquent cortex. Clinical article

OBJECT

The authors undertook this study to review their experience with cortical resections in the rolandic region in children with intractable epilepsy.

METHODS

The authors retrospectively reviewed the medical records obtained in 22 children with intractable epilepsy arising from the rolandic region. All patients underwent preoperative electroencephalography (EEG), MR imaging, prolonged video-EEG recordings, functional MR imaging, magnetoencephalography, and in some instances PET/SPECT studies. In 21 patients invasive subdural grid and depth electrode monitoring was performed. Resection of the epileptogenic zones in the rolandic region was undertaken in all cases. Seizure outcome was graded according to the Engel classification. Functional outcome was determined using validated outcome scores.

RESULTS

There were 10 girls and 12 boys, whose mean age at seizure onset was 3.2 years. The mean age at surgery was 10 years. Seizure duration prior to surgery was a mean of 7.4 years. Nine patients had preoperative hemiparesis. Neuropsychological testing revealed impairment in some domains in 19 patients in whom evaluation was possible. Magnetic resonance imaging abnormalities were identified in 19 patients. Magnetoencephalography was performed in all patients and showed perirolandic spike clusters on the affected side in 20 patients. The mean duration of invasive monitoring was 4.2 days. The mean number of seizures during the period of invasive monitoring was 17. All patients underwent resection that involved primary motor and/or sensory cortex. The most common pathological entity encountered was cortical dysplasia, in 13 children. Immediately postoperatively, 20 patients had differing degrees of hemiparesis, from mild to severe. The hemiparesis improved in all affected patients by 3-6 months postoperatively. With a mean follow-up of 4.1 years (minimum 2 years), seizure outcome in 14 children (64%) was Engel Class I and seizure outcome in 4 (18%) was Engel Class II. In this series, seizure outcome following perirolandic resection was intimately related to the child's age at the time of surgery. By univariate logistic regression analysis, age at surgery was a statistically significant factor predicting seizure outcome (p < 0.024).

CONCLUSIONS

Resection of rolandic cortex for intractable epilepsy is possible with expected morbidity. Accurate mapping of regions of functional cortex and epileptogenic zones may lead to improved seizure outcome in children with intractable rolandic epilepsy. It is important to counsel patients and families preoperatively to prepare them for possible worsened functional outcome involving motor, sensory and/or language pathways.

Is it worth pursuing surgery for epilepsy in patients with normal neuroimaging?

OBJECTIVE

To determine whether it is worth pursuing surgery for the treatment of epilepsy in patients with normal neuroimaging.

METHODS

Two patient populations were studied: (1) 136 consecutive patients who were surgically treated; (2) 105 consecutive patients assessed with chronically implanted intracranial electrodes within the same period. Sixty patients belonged to both groups, and included all 21 patients who had normal neuroimaging.

RESULTS

There were no differences in the proportion of patients with favourable outcome between those with normal and those with abnormal neuroimaging, irrespective of whether intracranial recordings were required. Among the 19 operated patients with normal neuroimaging, 74% had a favourable outcome (Engel's seizure outcome grades I and II), and among the 93 patients with abnormal neuroimaging, 73% had favourable outcome (p = 0.96). In patients with temporal resections, 92% of the 13 patients with normal neuroimaging had a favourable outcome, whereas among the 70 patients with abnormal neuroimaging, 80% had a favourable outcome (p = 0.44). In patients with extratemporal resections, two of the six patients with normal neuroimaging had a favourable outcome, while 12 of the 23 patients with abnormal neuroimaging had a favourable outcome (p = 0.65). Among the 105 patients studied with intracranial electrodes, five suffered transitory deficits as a result of implantation, and two suffered permanent deficits (one hemiplegia caused by haematoma and one mild dysphasia resulting from haemorrhage).

CONCLUSIONS

It is worth pursuing surgery in patients with normal neuroimaging because it results in good seizure control and the incidence of permanent deficits associated with intracranial studies is low.