Post operative supplementary motor area syndrome: clinical features and outcome

Permanent deterioration of fine motor skills after the resection of tumors in the supplementary motor area

Supplementary motor area syndrome (SMAS) represents a common neurosurgical sequela. The incidence and time frame of its occurrence have yet to be characterized after surgery for brain tumors. We examined patients suffering from a brain tumor preoperatively, postoperatively, and during follow-up examinations after three months, including fine motor skills testing and transcranial magnetic stimulation (TMS). 13 patients suffering from a tumor in the dorsal part of the superior frontal gyrus underwent preoperative, early postoperative, and 3-month follow-up testing of fine motor skills using the Jebsen-Taylor Hand Function Test (JHFT) and the Nine-Hole Peg Test (NHPT) consisting of 8 subtests for both upper extremities. They completed TMS for cortical motor function mapping. Test completion times (TCTs) were recorded and compared. No patient suffered from neurological deficits before surgery. On postoperative day one, we detected motor deficits in two patients, which remained clinically stable at a 3-month follow-up. Except for page-turning, every subtest indicated a significant worsening of function, reflected by longer TCTs (p < 0.05) in the postoperative examinations for the contralateral upper extremity (contralateral to the tumor manifestation). At 3-month follow-up examinations for the contralateral upper extremity, each subtest indicated significant worsening compared to the preoperative status despite improvement to the immediate postoperative level. We also detected significantly longer TCTs (p < 0.05) postoperatively in the ipsilateral upper extremity. This study suggests a long-term worsening of fine motor skills even three months after SMA tumor resection, indicating the necessity of targeted physical therapy for these patients.

Persistent hemiplegia with normal intraoperative neurophysiological monitoring in supratentorial neurosurgery: a case report and review of literature

Intraoperative neurophysiological monitoring (IONM) is needed for evaluating and demonstrating the integrity of the central and peripheral nervous system during surgical manoeuvres that take place in proximity to eloquent motor and somatosensory nervous structures. The integrity of the monitored motor pathways is not always followed by consistent clinical normality, particularly in the first hours/days following surgery, when surgical resection involves brain structures such as the supplementary motor areas (SMA). We report the case of a patient who underwent surgical excision of a right frontal glioblastoma with normal preoperative, intraoperative (IONM), and postoperative central motor conduction, but with persistent postoperative hemiplegia (> 6 months). The literature regarding SMA syndrome and its diagnosis and prognosis is reviewed.

Mapping of the supplementary motor area using repetitive navigated transcranial magnetic stimulation

Background

The supplementary motor area (SMA) is important for motor and language function. Damage to the SMA may harm these functions, yet tools for a preoperative assessment of the area are still sparse.

Objective

The aim of this study was to validate a mapping protocol using repetitive navigated transcranial magnetic stimulation (rnTMS) and extend this protocol for both hemispheres and lower extremities.

Methods

To this purpose, the SMA of both hemispheres were mapped based on a finger tapping task for 30 healthy subjects (35.97 ± 15.11, range 21-67 years; 14 females) using rnTMS at 20 Hz (120% resting motor threshold (RMT)) while controlling for primary motor cortex activation. Points with induced errors were marked on the corresponding MRI. Next, on the identified SMA hotspot a bimanual finger tapping task and the Nine-Hole Peg Test (NHPT) were performed. Further, the lower extremity was mapped at 20 Hz (140%RMT) using a toe tapping task.

Results

Mean finger tapping scores decreased significantly during stimulation (25.70taps) compared to baseline (30.48; p < 0.01). Bimanual finger tapping led to a significant increase in taps during stimulation (28.43taps) compared to unimanual tapping (p < 0.01). Compared to baseline, completion time for the NHPT increased significantly during stimulation (baseline: 13.6 s, stimulation: 16.4 s; p < 0.01). No differences between hemispheres were observed.

Conclusion

The current study validated and extended a rnTMS based protocol for the mapping of the SMA regarding motor function of upper and lower extremity. This protocol could be beneficial to better understand functional SMA organisation and improve preoperative planning in patients with SMA lesions.

Stereo-electroencephalography (SEEG)-Guided Surgery in Epilepsy With Cingulate Gyrus Involvement: Electrode Implantation Strategies and Postoperative Seizure Outcome

SUMMARY

Surgical treatment of cingulate gyrus epilepsy is associated with good results on seizures despite its rarity and challenging aspects. Invasive EEG monitoring is often mandatory to assess the epileptogenic zone in these patients. To date, only small surgical series have been published, and a consensus about management of these complex cases did not emerge. The authors retrospectively analyzed a large surgical series of patients in whom at least part of the cingulate gyrus was confirmed as included in the epileptogenic zone by means of stereo-electroencephalography and was thus resected. One hundred twenty-seven patients were selected. Stereo-electroencephalography-guided implantation of intracerebral electrodes was performed in the right hemisphere in 62 patients (48.8%) and in the left hemisphere in 44 patients (34.7%), whereas 21 patients (16.5%) underwent bilateral implantations. The median number of implanted electrodes per patient was 13 (interquartile range 12-15). The median number of electrodes targeting the cingulate gyrus was 4 (interquartile range 3-5). The cingulate gyrus was explored bilaterally in 19 patients (15%). Complication rate was 0.8%. A favorable outcome (Engel class I) was obtained in 54.3% of patients, with a median follow-up of 60 months. The chance to obtain seizure freedom increased in cases in whom histologic diagnosis was type-IIb focal cortical dysplasia or tumor (mostly ganglioglioma or dysembryoplastic neuroepithelial tumor) and with male gender. Higher seizure frequency predicted better outcome with a trend toward significance. Our findings suggest that stereo-electroencephalography is a safe and effective methodology in achieving seizure freedom in complex cases of epilepsy with cingulate gyrus involvement.

Role of interhemispheric connectivity in recovery from postoperative supplementary motor area syndrome in glioma patients

OBJECTIVE

Surgical resection of gliomas involving the supplementary motor area (SMA) frequently results in SMA syndrome, a symptom complex characterized by transient akinesia and mutism. Because the factors influencing patient functional outcomes after surgery remain elusive, the authors investigated network-based predictors in a multicentric cohort of glioma patients.

METHODS

The participants were 50 patients treated for glioma located in the SMA at one of the three centers participating in the study. Postoperative functional outcomes (motor deficits, mutism) and duration of symptoms were assessed during hospitalization. Long-term outcome was assessed 3 months after surgery. MRI-based lesion-symptom mapping was performed to estimate the severity of gray matter damage and white matter disconnection.

RESULTS

The median duration of acute symptoms was 3 days (range 1-42 days). Long-term deficits involving fine motor movements and speech were found at follow-up in 27 patients (54%). Disconnection of the central callosal fibers was associated with prolonged acute symptoms (p < 0.05). Postoperative mutism was significantly related to disconnection severity of the left frontopontine tract, frontal aslant tract, cingulum, and corticostriatal tract (p < 0.05). Disconnection of midposterior callosal fibers and lesion loads within the left medial Brodmann area 4 were associated with long-term motor deficits (p < 0.05).

CONCLUSIONS

This study provides evidence for the pathophysiology and predictive factors of postoperative SMA syndrome by demonstrating the relation of the disconnection of callosal fibers with prolonged symptom duration (central segment) and long-term motor deficits (midposterior segment). These data may be useful for presurgical risk assessment and adequate consultation for patients prior to undergoing resection of glioma located within the SMA region.

Italian reference values and brain correlates of verbal fluency index - vs standard verbal fluency test - to assess executive dysfunction in ALS

Objectives: In amyotrophic lateral sclerosis (ALS), verbal fluency index (Vfi) is used to investigate fluency accounting for motor impairment. This study has three aims: (1) to provide Vfi reference values from a cohort of Italian healthy subjects; (2) to assess the ability of Vfi reference values (vs standard verbal fluency test [VFT]) in distinguishing ALS patients with and without executive dysfunction; and (3) to investigate the association between Vfi and brain structural features of ALS patients. Methods: We included 180 healthy subjects and 157 ALS patients who underwent neuropsychological assessment, including VFT and Vfi, and brain MRI. Healthy subjects were split into four subgroups according to sex and education. For each subgroup, we defined the 95th percentile of Vfi as the cutoff. In ALS, the distributions of "abnormal" cases based on Vfi and standard VFT cutoffs were compared using Fisher's exact test. Using quantile regressions in patients, we assessed the association between Vfi and VFT scores, separately, with gray matter volumes and white matter (WM) tract integrity. Results: Applying Vfi and VFT cutoffs, 9 and 13% of ALS cases, respectively, had abnormal scores (p < 0.001). In ALS, while higher Vfi scores were associated with WM changes of callosal fibers linking supplementary motor area, lower VFT performances related to corticospinal tract alterations. Discussion: We provided Italian reference values for the spoken Vfi. Compared to VFT, Vfis are critical to disentangle motor and cognitive deficits in ALS. In patients, abnormal Vfis were associated with damage to WM tracts specifically involved in ideational information processing.

Deconvoluting human Brodmann area 8 based on its unique structural and functional connectivity

Brodmann area 8 (BA8) is traditionally defined as the prefrontal region of the human cerebrum just anterior to the premotor cortices and enveloping most of the superior frontal gyrus. Early studies have suggested the frontal eye fields are situated at its most caudal aspect, causing many to consider BA8 as primarily an ocular center which controls contralateral gaze and attention. However, years of refinement in cytoarchitectural studies have challenged this traditional anatomical definition, providing a refined definition of its boundaries with neighboring cortical areas and the presence of meaningful subdivisions. Furthermore, functional imaging studies have suggested its involvement in a diverse number of higher-order functions, such as motor, cognition, and language. Thus, our traditional working definition of BA8 has likely been insufficient to truly understand the complex structural and functional significance of this area. Recently, large-scale multi-modal neuroimaging approaches have allowed for improved mapping of the neural connectivity of the human brain. Insight into the structural and functional connectivity of the brain connectome, comprised of large-scale brain networks, has allowed for greater understanding of complex neurological functioning and pathophysiological diseases states. Simultaneously, the structural and functional connectivity of BA8 has recently been highlighted in various neuroimaging studies and detailed anatomic dissections. However, while Brodmann's nomenclature is still widely used today, such as for clinical discussions and the communication of research findings, the importance of the underlying connectivity of BA8 requires further review.

Protocol for mapping of the supplementary motor area using repetitive navigated transcranial magnetic stimulation

Background

Damage to the supplementary motor area (SMA) can lead to impairments of motor and language function. A detailed preoperative mapping of functional boarders of the SMA could therefore aid preoperative diagnostics in these patients.

Objective

The aim of this study was the development of a repetitive nTMS protocol for non-invasive functional mapping of the SMA while assuring effects are caused by SMA rather than M1 activation.

Methods

The SMA in the dominant hemisphere of 12 healthy subjects (28.2 ± 7.7 years, 6 females) was mapped using repetitive nTMS at 20 Hz (120% RMT), while subjects performed a finger tapping task. Reductions in finger taps were classified in three error categories (≤15% = no errors, 15-30% = mild, >30% significant). The location and category of induced errors was marked in each subject's individual MRI. Effects of SMA stimulation were then directly compared to effects of M1 stimulation in four different tasks (finger tapping, writing, line tracing, targeting circles).

Results

Mapping of the SMA was possible for all subjects, yet effect sizes varied. Stimulation of the SMA led to a significant reduction of finger taps compared to baseline (BL: 45taps, SMA: 35.5taps; p < 0.01). Line tracing, writing and targeting of circles was less accurate during SMA compared to M1 stimulation.

Conclusion

Mapping of the SMA using repetitive nTMS is feasible. While errors induced in the SMA are not entirely independent of M1, disruption of the SMA induces functionally distinct errors. These error maps can aid preoperative diagnostics in patients with SMA related lesions.

Relationship among Connectivity of the Frontal Aslant Tract, Executive Functions, and Speech and Language Impairment in Children with Childhood Apraxia of Speech

Childhood apraxia of speech (CAS) is a subtype of motor speech disorder usually co-occurring with language impairment. A supramodal processing difficulty, involving executive functions (EFs), might contribute to the cognitive endophenotypes and behavioral manifestations. The present study aimed to profile the EFs in CAS, investigating the relationship between EFs, speech and language severity, and the connectivity of the frontal aslant tract (FAT), a white matter tract involved in both speech and EFs. A total of 30 preschool children with CAS underwent speech, language, and EF assessments and brain MRIs. Their FAT connectivity metrics were compared to those of 30 children without other neurodevelopmental disorders (NoNDs), who also underwent brain MRIs. Alterations in some basic EF components were found. Inhibition and working memory correlated with speech and language severity. Compared to NoND children, a weak, significant reduction in fractional anisotropy (FA) in the left presupplementary motor area (preSMA) FAT component was found. Only speech severity correlated and predicted FA values along with the FAT in both of its components, and visual-spatial working memory moderated the relationship between speech severity and FA in the left SMA. Our study supports the conceptualization of a composite and complex picture of CAS, not limited to the speech core deficit, but also involving high-order cognitive skills.

Risk factors and prognostic implications of surgery-related strokes following resection of high-grade glioma

Surgery-related strokes are an important cause of morbidity following resection of high-grade glioma (HGG). We explored the incidence, risk factors and clinical consequences of intra-operative ischemic strokes in surgeries for resection of HGG. We retrospectively followed a cohort of 239 patients who underwent surgical resection of HGG between 2013 and 2017. Tumor types included both isocitrate dehydrogenase (IDH) wildtype glioblastoma and IDH-mutant WHO grade 4 astrocytoma. We analyzed pre- and post-operative demographic, clinical, radiological, anesthesiology and intraoperative neurophysiology data, including overall survival and functional outcomes. Acute ischemic strokes were seen on postoperative diffusion-weighted imaging (DWI) in 30 patients (12.5%), 13 of whom (43%) developed new neurological deficits. Infarcts were more common in insular (23%, p = 0.019) and temporal surgeries (57%, p = 0.01). Immediately after surgery, 35% of patients without infarcts and 57% of those with infarcts experienced motor deficits (p = 0.022). Six months later, rates of motor deficits decreased to 25% in the non-infarcts group and 37% in the infarcts group (p = 0.023 and 0.105, respectively) with a significantly lower Karnofsky-Performance Score (KPS, p = 0.001). Intra-operative language decline in awake procedures was a significant indicator of the occurrence of intra-operative stroke (p = 0.029). In conclusion, intraoperative ischemic events are more common in insular and temporal surgeries for resection of HGG and their intra-operative detection is limited. These strokes can impair motor and speech functions as well as patients' performance status.

Segregated circuits for phonemic and semantic fluency: A novel patient-tailored disconnection study

Phonemic and semantic fluency are neuropsychological tests widely used to assess patients' language and executive abilities and are highly sensitive tests in detecting language deficits in glioma patients. However, the networks that are involved in these tasks could be distinct and suggesting either a frontal (phonemic) or temporal (semantic) involvement. 42 right-handed patients (26 male, mean age = 52.5 years, SD=±13.3) were included in this retrospective study. Patients underwent awake (54.8%) or asleep (45.2%) surgery for low-grade (16.7%) or high-grade-glioma (83.3%) in the frontal (64.3%) or temporal lobe (35.7%) of the left (50%) or right (50%) hemisphere. Pre-operative tractography was reconstructed for each patient, with segmentation of the inferior fronto-occipital fasciculus (IFOF), arcuate fasciculus (AF), uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), third branch of the superior longitudinal fasciculus (SLF-III), frontal aslant tract (FAT), and cortico-spinal tract (CST). Post-operative percentage of damage and disconnection of each tract, based on the patients' surgical cavities, were correlated with verbal fluencies scores at one week and one month after surgery. Analyses of differences between fluency scores at these timepoints (before surgery, one week and one month after surgery) were performed; lesion-symptom mapping was used to identify the correlation between cortical areas and post-operative scores. Immediately after surgery, a transient impairment of verbal fluency was observed, that improved within a month. Left hemisphere lesions were related to a worse verbal fluency performance, being a damage to the left superior frontal or temporal gyri associated with phonemic or semantic fluency deficit, respectively. At a subcortical level, disconnection analyses revealed that fluency scores were associated to the involvement of the left FAT and the left frontal part of the IFOF for phonemic fluency, and the association was still present one month after surgery. For semantic fluency, the correlation between post-surgery performance emerged for the left AF, UF, ILF and the temporal part of the IFOF, but disappeared at the follow-up. This approach based on the patients' pre-operative tractography, allowed to trace for the first time a dissociation between white matter pathways integrity and verbal fluency after surgery for glioma resection. Our results confirm the involvement of a frontal anterior pathway for phonemic fluency and a ventral temporal pathway for semantic fluency. Finally, our longitudinal results suggest that the frontal executive pathway requires a longer interval to recover compared to the semantic one.

Outcomes of cingulate epilepsy surgery: insights from an institutional and patient-level systematic review and meta-analysis

OBJECTIVE

Due to their deep and medial location, range of seizure semiologies, and poor localization on ictal electroencephalography (EEG), cingulate gyrus seizures can be difficult to diagnose and treat. The aim of this study was to review the available evidence on postoperative outcomes after cingulate epilepsy surgery.

METHODS

A comprehensive literature search of the PubMed/MEDLINE, Ovid Embase, Ovid Scopus, and Cochrane Library databases was conducted to identify studies that investigated postoperative outcomes of patients with cingulate epilepsy. Seizure freedom at the last follow-up (at least 12 months) was the primary endpoint. The literature search was supplemented by the authors' institutional series (4 patients).

RESULTS

Twenty-one studies were identified, yielding a total of 105 patients (68 with lesional epilepsy [65%]). Median age at surgery was 23 years, and 56% of patients were male. Median epilepsy duration was 7.5 years. Invasive EEG recording was performed on 69% of patients (53% of patients with lesional epilepsy and 97% of those with nonlesional epilepsy, p < 0.001). The most commonly resected region was the anterior cingulate (55%), followed by the posterior (17%) and middle (14%) cingulate. Lesionectomy alone was performed in 9% of patients. Additional extracingulate treatment was performed in 54% of patients (53% of patients with lesional epilepsy vs 57% of those with nonlesional epilepsy, p = 0.87). The most common pathology was cortical dysplasia (54%), followed by low-grade neoplasm (29%) and gliosis (8%). Seizure freedom was noted in 72% of patients (median follow-up 24 months). A neurological deficit was noted in 27% of patients (24% had temporary deficit), with the most common deficit being motor weakness (13%) followed by supplementary motor area syndrome (9.5%). Univariate survival analysis revealed significantly greater probability of seizure freedom in patients with lesional epilepsy (p = 0.015, log-rank test).

CONCLUSIONS

Surgical treatment of drug-resistant focal epilepsy originating from the cingulate gyrus is safe, leads to low rates of permanent adverse effects, and leads to high rates of long-term seizure freedom in carefully selected patients. These data may serve as a benchmark for surgical counseling of patients with cingulate epilepsy.

Supplementary Motor Area Syndrome after Brain Tumor Surgery: A Systematic Review

BACKGROUND

Supplementary motor area syndrome (SMAS) may occur after frontal tumor surgery, with variable presentation and outcomes. We reviewed the literature on postoperative SMAS following brain tumor resection.

METHODS

PubMed, Web-of-Science, Scopus, and Cochrane were searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to include studies reporting SMAS after brain tumor resection.

RESULTS

We included 31 studies encompassing 236 patients. Most tumors were gliomas (94.5%), frequently of low-grade (61.4%). Most lesions were located on the left hemisphere (64.4%), involving the supplementary motor area (61.4%) and the cingulate gyrus (20.8%). Tractography and functional MRI evaluation were completed in 45 (19.1%) and 26 (11%) patients. Gross total resection was achieved in 46.3% cases and complete SMA resection in 69.4%. 215 procedures (91.1%) utilized intraoperative neuromonitoring mostly consisting of direct cortical/subcortical stimulation (56.4%), motor (33.9%), and somatosensory (25.4%) evoked potentials. Postoperative SMAS symptoms occurred within 24 hours after surgery, characterized by motor deficits (97%) including paresis (68.6%) and hemiplegia (16.1%), and speech disorders (53%) including hesitancy (24.2%) and mutism (22%). Average SMAS duration was 45 days (range, 1-365), with total resolution occurring in 188 patients (79.7%) and partial improvement in 46 (19.5%). 48 patients (20.3%) had persisting symptoms, mostly speech hesitancy (60.4%) and fine motor disorders (45.8%).

CONCLUSION

Postoperative SMAS may occur within the first 24 hours after mesial frontal tumor surgery. Preoperative mapping and intraoperative neuromonitoring may assist resection and predict outcomes. Neuroplasticity and interhemispheric connectivity play a major role in resolution.

Standardized reporting of adverse events and functional status from the first 5 years of awake surgery for gliomas: a population-based single-institution consecutive series

OBJECTIVE

To report our experience and investigate frequencies of adverse events and functional status from the first 5 years of performing awake surgery for gliomas in a single-center population-based setting.

METHODS

We conducted a review of all patients with a glioma treated with awake surgery during the first 5 years following introduction of awake surgery at our center (February 2015 to February 2020). We assessed functional and radiological outcome, with adverse events classified according to the Landriel-Ibanez classification for neurosurgical complications, while neurological deficits were further subdivided into transient vs permanent. We sought to analyze our initial results and learning curve, as well as compare our results with literature.

RESULTS

Forty-two patients were included. The median age was 38 years (range 18-66) and 13 (31%) were female. The indication for awake surgery was a presumed glioma in or near an eloquent area. The overall 30-day complication rate was 25 (59%), with 19 (45%) grade I complications, 3 (7%) grade II complications, and 3 (7%) grade III complications. Fifteen patients (36%) experienced transient neurological deficits, and 11 (26%) permanent neurological deficits. At 3-month follow-up, the Karnofsky Performance Score was 80 or higher for the entire cohort. The median extent of resection was 87%, with GTR achieved in 11 (26%). In search of potential learning curve difficulties, patients were divided into the 21 patients treated first (Early Group) versus the remaining 21 patients treated later (Late Group); no statistically significant difference in operating time, amount of tumor removed, or incidence of long-term postoperative neurological deficit was identified between groups. No awake surgery was aborted due to seizures. Comparison to the literature was limited by the diverse and unsystematic way in which previous studies have reported adverse events after awake craniotomy for gliomas.

CONCLUSION

We provide a standardized report of adverse events and functional status following awake surgery for glioma during a single-center 5-year learning period, with similar rates of severe adverse events and functional outcome compared to literature without concerns of substantial learning curve difficulties. However, this comparison was flawed by non-standardized reporting of complications, highlighting a demand for more standardized reporting of adverse events after awake craniotomies.

Multimodal approach leads to seizure-freedom in a case of highly refractory drug-resistant focal epilepsy

Drug-resistant, nonlesional, extratemporal lobe focal epilepsy can be difficult to treat and may require a high degree of multidisciplinary teamwork to localize the seizure onset zone for resective surgery. Here, we describe a patient with longstanding drug-resistant, nonlesional, extratemporal focal epilepsy with a high seizure burden who became seizure-free after prolonged evaluation and eventual left frontal cortical resection. Prior evaluations included magnetoencephalography, invasive video-EEG monitoring, and implantation of a responsive neurostimulation (RNS) device for ongoing intracranial stimulation. Highly sophisticated techniques were utilized including stereotactic localization of prior evaluations to guide repeat stereo-EEG (SEEG), electrical stimulation mapping, SEEG-guided radiofrequency ablation, and awake resection with language and motor mapping using a cognitive testing platform . Incorporating a wide array of data from multiple centers and evaluation time periods was necessary to optimize seizure control and minimize the risk of neurological deficits from surgery.

Postoperative Focal Lower Extremity Supplementary Motor Area Syndrome: Case Report and Review of the Literature

Supplementary motor area (SMA) syndrome refers to varying degrees of transient hemiparesis and mutism following insult to the medial posterior frontal lobe. We describe a rare case of an isolated lower limb SMA deficit with associated pre- and post-operative multimodality neurophysiological monitoring data. We review the literature on SMA somatotopy and the prognostic abilities of intraoperative motor evoked potentials in suspected SMA dysfunction. A 45-year-old male underwent staged resection of a complex parasagittal WHO grade II meningioma involving the posterior superior frontal gyrus bilaterally. Intraoperative neurophysiological monitoring with transcranial motor evoked potentials (TCMEP) and direct cortical motor evoked potentials (DCMEP) were used during both stages of resection. The patient developed an isolated left foot drop despite unchanged DCMEP and TCMEP data obtained during the first stage of the procedure. During the second stage of resection 3 days later, repeat neurophysiological monitoring confirmed intact corticospinal tracts. Deep peroneal somatosensory evoked potentials (SSEPs) revealed good morphology, appropriate latency and amplitudes during the second stage of resection. These results suggested a diagnosis of focal SMA dysfunction. Left foot drop persisted 7 days post-operatively. At one month follow up, the patient was neurologically intact with full strength noted in all muscle groups of the left lower extremity. An improved understanding of the somatotopic organization of the SMA with additional neuromonitoring data can allow neurosurgeons to better predict and understand perioperative SMA dysfunctions.

Comparison of seizure outcomes and ADL recovery period after total or anterior corpus callosotomy in adolescent and young adults with drop attacks and severe mental retardation

PURPOSE

The aim of this study was to evaluate seizure outcomes and postoperative neurologic complications, with an emphasis on the recovery period of activities of daily living (ADL) between anterior partial corpus callosotomy (ACC) and total corpus callosotomy (TCC) in adolescent and young adults with drop attacks and severe mental retardation.

METHODS

We retrospectively reviewed the clinical records of consecutive patients with intractable epilepsy who underwent corpus callosotomy (CC) for drop attacks between 2010 and 2019 in the Department of Neurosurgery, Hiroshima University hospital, with a minimum follow-up of one year. Inclusion criteria of this study were 1) age at surgery: 11-39 years, 2) preoperative intelligence quotient <35, and 3) preoperative Barthel index (BI) ≥30. Postoperative full ADL recovery was defined as complete recovery to the preoperative BI score. We compared the postoperative days required for 1) recovery of oral intake ability, 2) discharge from our hospital, 3) returning home from any hospital, 4) returning home with full ADL recovery, and 5) seizure outcomes in patients with ACC versus those with one-stage TCC.

RESULTS

Ten patients with ACC and 14 patients with one-stage TCC met the inclusion criteria. The period for returning home with full ADL recovery was a median of 15 days (range 9-45 days) after ACC, while the median was 21.5 days (range 10-62 days) after one-stage TCC (p = 0.2904). Although there was a tendency for the ADL recovery period to be longer after one-stage TCC, there were no statistically significant differences in any category of ADL recovery period. Eleven of 14 (78.6 %) patients who received a one-stage TCC showed favorable seizure outcomes, with drop attack cessation, which was significantly better than 1 of 10 (10 %) patients with ACC (p = 0.0009).

CONCLUSIONS

From the viewpoint of postoperative seizure outcomes and ADL recovery period, one-stage TCC is preferred to ACC for adolescent and young adults with severe mental retardation.

Language supplementary motor area syndrome correlated with dynamic changes in perioperative task-based functional MRI activations: case report

Supplementary motor area (SMA) syndrome is well known; however, the mechanism underlying recovery from language SMA syndrome is unclear. Herein the authors report the case of a right-handed woman with speech aphasia following resection of an oligodendroglioma located in the anterior aspect of the left superior frontal gyrus. The patient exhibited language SMA syndrome, and functional MRI (fMRI) findings 12 days postoperatively demonstrated a complete shift of blood oxygen level–dependent (BOLD) activation to the contralateral right language SMA/pre-SMA as well as coequal activation and an increased volume of activation in the left Broca’s area and the right Broca’s homolog. The authors provide, to the best of their knowledge, the first description of dynamic changes in task-based hemispheric language BOLD fMRI activations across the preoperative, immediate postoperative, and more distant postoperative settings associated with the development and subsequent complete resolution of the clinical language SMA syndrome.

Free will and neurosurgical resections of the supplementary motor area: a critical review

BACKGROUND

Research suggests that unconscious activity in the supplementary motor area (SMA) precedes not only certain simple motor actions but also the point at which we become aware of our intention to perform such actions. The extent to which these findings have implications for our understanding of the concepts of free will and personal responsibility has been subject of intense debate during the latest four decades.

METHODS

This research is discussed in relation to effects of neurosurgical removal of the SMA in a narrative review.

RESULTS

Removal of the SMA typically causes a transient inability to perform non-stimulus-driven, voluntary actions. This condition, known as the SMA syndrome, does not appear to be associated with a loss of sense of volition but with a profound disruption of executive function/cognitive control.

CONCLUSIONS

The role of the SMA may be to serve as a gateway between the corticospinal tract and systems for executive function. Such systems are typically seen as tools for conscious decisions. What is known about effects of SMA resections would thus seem to suggest a view that is compatible with concepts of personal responsibility. However, the philosophical question whether free will exists cannot be definitely resolved on the basis of these observations.

Long-term motor deficit in brain tumour surgery with preserved intra-operative motor-evoked potentials

Muscle motor-evoked potentials are commonly monitored during brain tumour surgery in motor areas, as these are assumed to reflect the integrity of descending motor pathways, including the corticospinal tract. However, while the loss of muscle motor-evoked potentials at the end of surgery is associated with long-term motor deficits (muscle motor-evoked potential-related deficits), there is increasing evidence that motor deficit can occur despite no change in muscle motor-evoked potentials (muscle motor-evoked potential-unrelated deficits), particularly after surgery of non-primary regions involved in motor control. In this study, we aimed to investigate the incidence of muscle motor-evoked potential-unrelated deficits and to identify the associated brain regions. We retrospectively reviewed 125 consecutive patients who underwent surgery for peri-Rolandic lesions using intra-operative neurophysiological monitoring. Intraoperative changes in muscle motor-evoked potentials were correlated with motor outcome, assessed by the Medical Research Council scale. We performed voxel–lesion–symptom mapping to identify which resected regions were associated with short- and long-term muscle motor-evoked potential-associated motor deficits. Muscle motor-evoked potentials reductions significantly predicted long-term motor deficits. However, in more than half of the patients who experienced long-term deficits (12/22 patients), no muscle motor-evoked potential reduction was reported during surgery. Lesion analysis showed that muscle motor-evoked potential-related long-term motor deficits were associated with direct or ischaemic damage to the corticospinal tract, whereas muscle motor-evoked potential-unrelated deficits occurred when supplementary motor areas were resected in conjunction with dorsal premotor regions and the anterior cingulate. Our results indicate that long-term motor deficits unrelated to the corticospinal tract can occur more often than currently reported. As these deficits cannot be predicted by muscle motor-evoked potentials, a combination of awake and/or novel asleep techniques other than muscle motor-evoked potentials monitoring should be implemented.

No prognostic differences between GBM-patients presenting with postoperative SMA-syndrome and GBM-patients involving cortico-spinal tract and primary motor cortex

BACKGROUND

The supplementary motor area (SMA) is involved in several aspects of motor control and its can be associated to a contralateral motor deficit and speech disorders. After the resection of low-grade gliomas, this syndrome is diffusely reported but it is rarely investigated in high-grade gliomas. SMA deficits may resolve completely or with minor sequelae within weeks. Whether this condition of transient deficit affects survival, was not previously investigated, and is not currently understood.

OBJECTIVE

The study aimed to perform an accurate investigation concerning the real clinical and prognostic impact of the postoperative SMA syndrome in order to shed light over its relationship to survival parameters and postoperative functional status of the patients.

METHODS

We performed a retrospective review of a series of 176 surgically treated patients suffering from Glioblastomas. Tumors classified as Group A: Involving the SMA and Group B: Lesion located outside and distal to the SMA but in anatomical relationship to primary motor cortices (PM1) or corticospinal tract (CST), in order to investigate differences concerning immunohistochemical and molecular profiles in regard to the survival parameters.

RESULTS

Although lesions involving SMA demonstrated a significantly higher volume in respect to their general counterparts they did not significantly differ in concerns to the molecular patterns, pre and postoperative KPS scores and in PFS and OS findings.

CONCLUSIONS

In our cohort SMA-syndrome is reversible and therefore guarantees a satisfactory functional status at follow-up, apparently not compromising survival when compared to other lesions affecting the primary or cortical motor area -spinal tract.

Challenges of Epilepsy Surgery

Though frequently effective in the management of medically refractory seizures, epilepsy surgery presents numerous challenges. Selection of the appropriate candidate patients who are likely to benefit from surgery is critical to achieving seizure freedom and avoiding neurocognitive morbidity. Identifying the seizure focus and mapping epileptogenic networks involves an interdisciplinary team dedicated to formulating a safe and effective surgical plan. Various strategies can be employed either to eliminate the epileptic focus or to modulate network activity, including resection of the focus with open surgery or laser interstitial thermal therapy; modulation of epileptogenic firing patterns with responsive neurostimulation, deep brain stimulation, or vagus nerve stimulation; or non-invasive disconnection of epileptic circuits with focused ultrasound, which is also discussed in greater detail in the subsequent chapter in our series. We review several challenges of epilepsy surgery that must be thoughtfully addressed in order to ensure its success.

Sex Effect on Presurgical Language Mapping in Patients With a Brain Tumor

Differences between males and females in brain development and in the organization and hemispheric lateralization of brain functions have been described, including in language. Sex differences in language organization may have important implications for language mapping performed to assess, and minimize neurosurgical risk to, language function. This study examined the effect of sex on the activation and functional connectivity of the brain, measured with presurgical functional magnetic resonance imaging (fMRI) language mapping in patients with a brain tumor. We carried out a retrospective analysis of data from neurosurgical patients treated at our institution who met the criteria of pathological diagnosis (malignant brain tumor), tumor location (left hemisphere), and fMRI paradigms [sentence completion (SC); antonym generation (AG); and resting-state fMRI (rs-fMRI)]. Forty-seven patients (22 females, mean age = 56.0 years) were included in the study. Across the SC and AG tasks, females relative to males showed greater activation in limited areas, including the left inferior frontal gyrus classically associated with language. In contrast, males relative to females showed greater activation in extended areas beyond the classic language network, including the supplementary motor area (SMA) and precentral gyrus. The rs-fMRI functional connectivity of the left SMA in the females was stronger with inferior temporal pole (TP) areas, and in the males with several midline areas. The findings are overall consistent with theories of greater reliance on specialized language areas in females relative to males, and generalized brain areas in males relative to females, for language function. Importantly, the findings suggest that sex could affect fMRI language mapping. Thus, considering sex as a variable in presurgical language mapping merits further investigation.

Postoperative isolated lower extremity supplementary motor area syndrome: case report and review of the literature

The supplementary motor area (SMA) syndrome is characterized by transient weakness and akinesia contralateral to the side of the affected hemisphere. The underlying pathology of the syndrome is not fully understood but is thought to be related to lesions in the SMA, residing principally in the mesial superior frontal gyrus (Broadmann's area 6c). Although the SMA syndrome a well-characterized clinical entity, we report herein, to our knowledge, the first case of isolated lower extremity SMA syndrome in the literature. This case highlights the importance of considering this rare clinical entity in the context of new or worsening postoperative neurologic deficits. Moreover, early studies did not support somatotopic organization of the SMA as in the primary motor cortex; emerging evidence suggests that delicate somatotopic representation may underlie distinct presentations like that reported in the present case.

Incidence and impact of stroke following surgery for low-grade gliomas

OBJECTIVE

Ischemic complications are a common cause of neurological deficits following low-grade glioma (LGG) surgeries. In this study, the authors evaluated the incidence, risk factors, and long-term implications of intraoperative ischemic events.

METHODS

The authors retrospectively evaluated patients who had undergone resection of an LGG between 2013 and 2017. Analysis included pre- and postoperative demographic, clinical, radiological, and anesthetic data, as well as intraoperative neurophysiology data, overall survival, and functional and neurocognitive outcomes.

RESULTS

Among the 82 patients included in the study, postoperative diffusion-weighted imaging showed evidence of acute ischemic strokes in 19 patients (23%), 13 of whom (68%) developed new neurological deficits. Infarcts were more common in recurrent and insular surgeries (p < 0.05). Survival was similar between the patients with and without infarcts. Immediately after surgery, 27% of the patients without infarcts and 58% of those with infarcts experienced motor deficits (p = 0.024), decreasing to 16% (p = 0.082) and 37% (p = 0.024), respectively, at 1 year. Neurocognitive functions before and 3 months after surgery were generally stable for the two groups, with the exception of a decline in verbal rhyming ability among patients with infarcts. Confusion during awake craniotomy was a strong predictor of the occurrence of an ischemic stroke. Mean arterial pressure at the beginning of surgery was significantly lower in the infarct group.

CONCLUSIONS

Recurrent surgeries and insular tumor locations are risk factors for intraoperative strokes. Although they do not affect survival, these strokes negatively affect patient activity and performance status, mainly during the first 3 postoperative months, with gradual functional improvement over 1 year. Several intraoperative parameters may suggest the impending development of an infarct.

The supplementary motor area syndrome and cognitive control

The Supplementary Motor Area (SMA)-syndrome is a transient disturbance of the ability to initiate voluntary motor and speech actions that will often occur immediately after neurosurgical resections in the dorsal superior frontal gyrus but will typically have disappeared after 3 months. The purpose of the present study was to investigate the extent to which this syndrome is associated with alterations in cognitive control. Five patients who were to different extents affected by the SMA-syndrome after surgery for WHO grade II gliomas in the left hemisphere, were tested with the color word interference (Stroop) test; the Bergen dichotic listening test and for letter and category verbal fluency before surgery, 1-2 days after surgery and approximately 3 months after surgery. Results suggest that the motor symptoms known as the SMA syndrome co-occur with pronounced deficits in cognitive control.

The frontal aslant tract (FAT) and its role in speech, language and executive function

In this review, we examine the structural connectivity of a recently-identified fiber pathway, the frontal aslant tract (FAT), and explore its function. We first review structural connectivity studies using tract-tracing methods in non-human primates, and diffusion-weighted imaging and electrostimulation in humans. These studies suggest a monosynaptic connection exists between the lateral inferior frontal gyrus and the pre-supplementary and supplementary motor areas of the medial superior frontal gyrus. This connection is termed the FAT. We then review research on the left FAT's putative role in supporting speech and language function, with particular focus on speech initiation, stuttering and verbal fluency. Next, we review research on the right FAT's putative role supporting executive function, namely inhibitory control and conflict monitoring for action. We summarize the extant body of empirical work by suggesting that the FAT plays a domain general role in the planning, timing, and coordination of sequential motor movements through the resolution of competition among potential motor plans. However, we also propose some domain specialization across the hemispheres. On the left hemisphere, the circuit is proposed to be specialized for speech actions. On the right hemisphere, the circuit is proposed to be specialized for general action control of the organism, especially in the visuo-spatial domain. We close the review with a discussion of the clinical significance of the FAT, and suggestions for further research on the pathway.

Intraoperative monitoring of motor-evoked potential for parenchymal brain tumor removal: An analysis of false-negative cases

Transcranial motor-evoked potential (tc-MEP) monitoring is unreliable for brain tumor removal due to its low sensitivity. According to previous literature, this is because transcranial stimulation seems to reach the deep pyramidal tract beyond the operation point and may thus yield false-negative results, where, although MEP recording is stable, postoperative motor deficits are encountered. Therefore, we aimed to analyze the causes for the false-negative results and investigate whether decreasing the stimulation intensity better reflects the operation point and can improve the sensitivity during parenchymal brain tumor removal. We assessed 122 patients with parenchymal brain and intraventricular tumors, who underwent surgery under tc-MEP monitoring in our hospital between 2011 and 2014. In these patients, the stimulation intensity was fixed at 200 mA. We detected 11 false-negative cases, while the sensitivity of tc-MEP monitoring was 33.9% and the specificity was 99.0%. Between 2015 and 2016, we examined 68 patients with parenchymal brain tumors, in whom the stimulation intensity was reduced to an average of 136.5 mA. Only one case was false-negative, while the sensitivity increased to 83.3% and the specificity was 98.4%. From these results, we conclude that the intensity of tc-MEP stimulation should be minimal to precisely reflect the damage to the operated location. Tc-MEP can be an easy and reliable monitor in brain tumor surgery when used at proper, lower intensity.

Bringing order to higher order motor disorders

Majority of movements in everyday situations are complex and involve volition, planning of the movement and selection of the motor programme, all occurring before movement execution. Higher order motor disorders may be defined as abnormal motor behaviours resulting from disruption of any of the cortical processes that precede execution of the motor act. They are common in patients with neurodegenerative disorders, psychiatric diseases and structural brain lesions. These abnormal behaviours may be overlooked in the clinic, unless specifically evoked by the examiner. We discuss clinical and pathophysiological aspects of higher order motor disorders including: (1) disorders of disinhibition, such as grasp reflex and grasping behaviour, utilisation and imitation behaviour, motor preservations and paratonia; (2) disorders of motor intention such as motor neglect and motor impersistence; (3) alien limb syndrome; and (4) motor overflow phenomena, such as mirror movements and synkinesias. A video illustration of each phenomenon is provided. We place the findings from recent neurophysiological studies within the framework of theories of motor control to provide better insight into pathophysiology of different disorders.

Working Memory Deficits After Lesions Involving the Supplementary Motor Area

The Supplementary Motor Area (SMA)—located in the superior and medial aspects of the superior frontal gyrus—is a preferential site of certain brain tumors and arteriovenous malformations, which often provoke the so-called SMA syndrome. The bulk of the literature studying this syndrome has focused on two of its most apparent symptoms: contralateral motor and speech deficits. Surprisingly, little attention has been given to working memory (WM) even though neuroimaging studies have implicated the SMA in this cognitive process. Given its relevance for higher-order functions, our main goal was to examine whether WM is compromised in SMA lesions. We also asked whether WM deficits might be reducible to processing speed (PS) difficulties. Given the connectivity of the SMA with prefrontal regions related to executive control (EC), as a secondary goal we examined whether SMA lesions also hampered EC. To this end, we tested 12 patients with lesions involving the left (i.e., the dominant) SMA. We also tested 12 healthy controls matched with patients for socio-demographic variables. To ensure that the results of this study can be easily transferred and implemented in clinical practice, we used widely-known clinical neuropsychological tests: WM and PS were measured with their respective Wechsler Adult Intelligence Scale indexes, and EC was tested with phonemic and semantic verbal fluency tasks. Non-parametric statistical methods revealed that patients showed deficits in the executive component of WM: they were able to sustain information temporarily but not to mentally manipulate this information. Such WM deficits were not subject to patients' marginal PS impairment. Patients also showed reduced phonemic fluency, which disappeared after controlling for the influence of WM. This observation suggests that SMA damage does not seem to affect cognitive processes engaged by verbal fluency other than WM. In conclusion, WM impairment needs to be considered as part of the SMA syndrome. These findings represent the first evidence about the cognitive consequences (other than language) of damage to the SMA. Further research is needed to establish a more specific profile of WM impairment in SMA patients and determine the consequences of SMA damage for other cognitive functions.

The crossed frontal aslant tract: A possible pathway involved in the recovery of supplementary motor area syndrome

INTRODUCTION

Supplementary motor area (SMA) syndrome is a constellation of temporary symptoms that may occur following tumors of the frontal lobe. Affected patients develop akinesia and mutism but often recover within weeks to months. With our own case examples and with correlations to fiber tracking validated by gross anatomical dissection as ground truth, we describe a white matter pathway through which recovery may occur.

METHODS

Diffusion spectrum imaging from the Human Connectome Project was used for tractography analysis. SMA outflow tracts were mapped in both hemispheres using a predefined seeding region. Postmortem dissections of 10 cadaveric brains were performed using a modified Klingler technique to verify the tractography results.

RESULTS

Two cases were identified in our clinical records in which patients sustained permanent SMA syndrome after complete disconnection of the SMA and corpus callosum (CC). After investigating the postoperative anatomy of these resections, we identified a pattern of nonhomologous connections through the CC connecting the premotor area to the contralateral premotor and SMAs. The transcallosal fibers have projections from the previously described frontal aslant tract (FAT) and thus, we have termed this path the "crossed FAT."

CONCLUSIONS

We hypothesize that this newly described tract may facilitate recovery from SMA syndrome by maintaining interhemispheric connectivity through the supplementary motor and premotor areas.

Supplementary motor area syndrome after surgery for parasagittal meningiomas

BACKGROUND

Resection within the supplementary motor area (SMA) may be accompanied by dramatic motor deficits and speech arrest when the dominant hemisphere is involved, termed the SMA syndrome. Typically, the muscle tone of the paralyzed extremities is preserved, and in most cases, a complete or near complete recovery is seen within a few months. The SMA syndrome has not been recognized for extra-axial tumor surgery in approximation of the SMA.

METHODS

We observed the SMA syndrome in a patient operated for a parasagittal meningioma in the posterior frontal region, and this observation intrigued us to prospectively collect similar cases.

RESULTS

In the period from January 2010 to December 2015, we observed five patients who developed a partial SMA syndrome after surgery for frontal parasagittal meningiomas. The muscle tone was preserved in the affected extremities. All patients experienced improvement in motor function within a few days, and on follow-up, three out of five patients had recovered completely. Three of the patients had meningioma WHO grade II.

CONCLUSIONS

Surgically induced SMA syndrome can easily be confused with pyramidal weakness. This series of cases demonstrate that the syndrome may also develop after removal of extra-axial tumors and is probably underdiagnosed and underreported. The good functional prognosis is helpful in the preoperative counseling and follow-up of these patients.

Cerebellar Mutism Syndrome and Other Complications After Surgery in the Posterior Fossa in Adults: A Prospective Study

BACKGROUND

Cerebellar mutism syndrome (CMS) is rarely described in adults; however, data on self-assessed linguistic complications after posterior fossa surgery do not exist.

METHODS

Through a prospective single-center study, data on 59 tumor operations in the posterior fossa were collected preoperatively as well as 1 week and 1 month postoperatively. Data on self-assessed problems in 5 CMS-related domains, CMS scores, and neurology as well as surgical procedure and complications were obtained.

RESULTS

Data on CMS-related complications were obtained on 56 of the 59 operations. None was found to have CMS according to the CMS score. Within each of the 5 domains, at least 9 operations (16%) were followed by development or worsening of self-assessed CMS-related complications. Self-assessed complications were found to be most frequent after primary tumor surgeries, although they were significant only for speech and motor complications (P value = 0.01 and 0.02). Speech and language complications occurred more frequently in midline tumors compared with lateral tumors (40% vs. 7%; P = 0.004). Surgical complications were similar to other studies.

CONCLUSIONS

We propose that speech and language problems in adults undergoing surgery in the posterior fossa occur more frequently than previously assumed. Some of the self-assessed complications might reflect components of the cerebellar cognitive affective syndrome. Our findings are consistent with the fact that midline location of the tumor is one of the few known risk factors for CMS in children. Thus, the cerebellar midline seems to be a vulnerable region for speech and language complications also in adults.

Language recovery after epilepsy surgery of the Broca's area

Epilepsy surgery is indicated in select patients with drug-resistant focal epilepsy. Seizure freedom or significant reduction of seizure burden without risking new neurological deficits is the expected goal of epilepsy surgery. Typically, when the seizure onset zone overlaps with eloquent cortex, patients are excluded from surgery. We present a patient with drug-resistant frontal lobe epilepsy who underwent successful surgery with resection of Broca's area, primarily involving the pars triangularis (BA 45). We report transient expressive aphasia followed by recovery of speech. This case provides new insights into adult neuroplasticity of the language network.

Resection of Navigated Transcranial Magnetic Stimulation-Positive Prerolandic Motor Areas Causes Permanent Impairment of Motor Function

BACKGROUND: Navigated transcranial magnetic stimulation (nTMS) helps to determine the distribution of motor eloquent areas prior to brain surgery. Yet, the eloquence of primary motor areas frontal to the precentral gyrus identified via nTMS is unclear.

OBJECTIVE: To investigate the resection of nTMS-positive prerolandic motor areas and its correlation with postsurgical impairment of motor function.

METHODS: Forty-three patients with rolandic or prerolandic gliomas (WHO grade I-IV) underwent nTMS prior to surgery. Only patients without ischemia within the motor system in postoperative MRI diffusion sequences were enrolled. Based on the 3-dimensional fusion of preoperative nTMS motor mapping data with postsurgical MRI scans, we identified nTMS points that were resected in the infiltration zone of the tumor. We then classified the resected points according to the localization and latency of their motor evoked potentials. Surgery-related paresis was graded as transient (≤6 weeks) or permanent (&gt;6 weeks).

RESULTS: Out of 43, 31 patients (72%) showed nTMS-positive motor points in the prerolandic gyri. In general, 13 out of 43 patients (30%) underwent resection of nTMS points. Ten out of these patients showed postoperative paresis. There were 2 (15%) patients with a transient and 8 (62%) with a permanent surgery-related paresis. In 3 cases (23%), motor function remained unimpaired.

CONCLUSION: After resection of nTMS-positive motor points, 62% of patients suffered from a new permanent paresis. Thus, even though they are located in the superior or middle frontal gyrus, these cortical areas must undergo intraoperative mapping.

Long-term surgical results of supplementary motor area epilepsy surgery

OBJECTIVE Supplementary motor area (SMA) epilepsy is a well-known clinical condition; however, long-term surgical outcome reports are scarce and correspond to small series or isolated case reports. The aim of this study is to present the surgical results of SMA epilepsy patients treated at 2 reference centers in Mexico City. METHODS For this retrospective descriptive study (1999-2014), 52 patients underwent lesionectomy and/or corticectomy of the SMA that was guided by electrocorticography (ECoG). The clinical, neurophysiological, neuroimaging, and pathological findings are described. The Engel scale was used to classify surgical outcome. Descriptive statistics, Student t-test, and Friedman, Kruskal-Wallis, and chi-square tests were used. RESULTS Of these 52 patients, the mean age at epilepsy onset was 26.3 years, and the mean preoperative seizure frequency was 14 seizures per month. Etiologies included low-grade tumors in 28 (53.8%) patients, cortical dysplasia in 17 (32.7%) patients, and cavernomas in 7 (13.5%) patients. At a mean follow-up of 5.7 years (range 1-10 years), 32 patients (61%) were classified as Engel Class I, 16 patients (31%) were classified as Engel Class II, and 4 (8%) patients were classified as Engel Class III. Overall seizure reduction was significant (p = 0.001). The absence of early postsurgical seizures and lesional etiology were associated with the outcome of Engel Class I (p = 0.05). Twenty-six (50%) patients had complications in the immediate postoperative period, all of which resolved completely with no residual neurological deficits. CONCLUSIONS Surgery for SMA epilepsy guided by ECoG using a multidisciplinary and multimodality approach is a safe, feasible procedure that shows good seizure control, moderate morbidity, and no mortality.

Neuropsychological outcome following frontal lobectomy for pharmacoresistant epilepsy in adults

OBJECTIVE

This retrospective cohort study characterized cognitive and motor outcomes in a large sample of adults who underwent frontal lobe resections for treatment of pharmacoresistant epilepsy.

METHODS

Ninety patients who underwent unilateral frontal lobe resection for epilepsy (42 language-dominant hemisphere/48 nondominant hemisphere) between 1989 and 2014 completed comprehensive preoperative and postoperative neuropsychological evaluations that included measures of verbal and nonverbal intellectual functioning, attention/working memory, processing speed, language, executive functioning, verbal and visual memory, and motor functioning. Objective methods were used to assess meaningful change across a wide range of abilities and to identify factors associated with neuropsychological decline following frontal lobectomy. Detailed postoperative neuroimaging analysis was conducted to characterize region, extent, and volume of resection.

RESULTS

Forty-eight percent of patients did not demonstrate meaningful postoperative declines in cognition and an additional 42% demonstrated decline in 1 or 2 cognitive domains. When cognitive decline was observed, it usually occurred on measures of intelligence, visuomotor processing speed, or executive functioning. Side and site of resection were unrelated to cognitive outcome, but played a role in decline of contralateral manual dexterity following supplementary motor area resection. Higher preoperative ability, older age at surgery, absence of a malformation of cortical development on MRI, and poor seizure outcome were related to cognitive decline on some measures, but had poor sensitivity in identifying at-risk patients.

CONCLUSIONS

The vast majority of patients who undergo frontal lobectomy for treatment of pharmacoresistant epilepsy demonstrate good cognitive and motor outcomes.

A method for safely resecting anterior butterfly gliomas: the surgical anatomy of the default mode network and the relevance of its preservation

OBJECTIVE

Gliomas invading the anterior corpus callosum are commonly deemed unresectable due to an unacceptable risk/benefit ratio, including the risk of abulia. In this study, the authors investigated the anatomy of the cingulum and its connectivity within the default mode network (DMN). A technique is described involving awake subcortical mapping with higher attention tasks to preserve the cingulum and reduce the incidence of postoperative abulia for patients with so-called butterfly gliomas.

METHODS

The authors reviewed clinical data on all patients undergoing glioma surgery performed by the senior author during a 4-year period at the University of Oklahoma Health Sciences Center. Forty patients were identified who underwent surgery for butterfly gliomas. Each patient was designated as having undergone surgery either with or without the use of awake subcortical mapping and preservation of the cingulum. Data recorded on these patients included the incidence of abulia/akinetic mutism. In the context of the study findings, the authors conducted a detailed anatomical study of the cingulum and its role within the DMN using postmortem fiber tract dissections of 10 cerebral hemispheres and in vivo diffusion tractography of 10 healthy subjects.

RESULTS

Forty patients with butterfly gliomas were treated, 25 (62%) with standard surgical methods and 15 (38%) with awake subcortical mapping and preservation of the cingulum. One patient (1/15, 7%) experienced postoperative abulia following surgery with the cingulum-sparing technique. Greater than 90% resection was achieved in 13/15 (87%) of these patients.

CONCLUSIONS

This study presents evidence that anterior butterfly gliomas can be safely removed using a novel, attention-task based, awake brain surgery technique that focuses on preserving the anatomical connectivity of the cingulum and relevant aspects of the cingulate gyrus.

Macrostructural and Microstructural Brain Lesions Relate to Gait Pathology in Children With Cerebral Palsy

Background. Even though lower-limb motor disorders are core features of spastic cerebral palsy (sCP), the relationship with brain lesions remains unclear. Unraveling the relation between gait pathology, lower-limb function, and brain lesions in sCP is complex for several reasons; wide heterogeneity in brain lesions, ongoing brain maturation, and gait depends on a number of primary motor functions/deficits (eg, muscle strength, spasticity). Objective. To use a comprehensive approach combining conventional MRI and diffusion tensor imaging (DTI) in children with sCP above 3 years old to relate quantitative parameters of brain lesions in multiple brain areas to gait performance. Methods. A total of 50 children with sCP (25 bilateral, 25 unilateral involvement) were enrolled. The investigated neuroradiological parameters included the following: (1) volumetric measures of the corpus callosum (CC) and lateral ventricles (LVs), and (2) DTI parameters of the corticospinal tract (CST). Gait pathology and primary motor deficits, including muscle strength and spasticity, were evaluated by 3D gait analysis and clinical examination. Results. In bilateral sCP (n = 25), volume of the LV and the subparts of the CC connecting frontal, (pre)motor, and sensory areas were most related to lower-limb functioning and gait pathology. DTI measures of the CST revealed additional relations with the primary motor deficits (n = 13). In contrast, in unilateral sCP, volumetric (n = 25) and diffusion measures (n = 14) were only correlated to lower-limb strength. Conclusions. These results indicate that the combined influence of multiple brain lesions and their impact on the primary motor deficits might explain a large part of the gait pathology in sCP.

Recurrent Supplementary Motor Area Syndrome Following Repeat Brain Tumor Resection Involving Supplementary Motor Cortex

BACKGROUND

Supplementary motor area (SMA) syndrome occurs after surgery involving the SMA and is characterized by contralateral hemiparesis with or without speech impairment (dependent on involvement of the dominant SMA), which is transient and characteristically resolves over the course of weeks to months. Recurrent SMA syndrome after repeat craniotomy has not been previously described.

OBJECTIVE

To describe the presentation and clinical course of patients who developed recurrent SMA syndrome after redo resection of tumors involving the SMA.

METHODS

We performed a retrospective review of 15 patients who underwent repeated resection of low-grade glioma from the superior and middle frontal gyrus. Of these patients, we identified 6 cases of recurrent SMA syndrome.

RESULTS

Six patients had a documented SMA syndrome occurring after initial and subsequent resection of tumor in proximity to the SMA. Intraoperative localization of eloquent motor and language cortex was achieved in each patient by using a combination of somatosensory evoked potentials and electrocortical stimulation mapping. Location of tumor and extent of resection was examined with magnetic resonance imaging.

CONCLUSION

This series demonstrates that recurrent SMA syndrome occurs in patients undergoing repeat resection of tumors involving the SMA. The presence of recurrent SMA syndrome provides support for reorganization of SMA function to adjacent ipsilateral cortex after resection. Patients with recurrent neoplasms of the SMA should be counseled on the possibility of recurrent SMA syndrome.

Pre-operative fMRI localization of the supplementary motor area and its relationship with postoperative speech deficits

INTRODUCTION

Neurosurgery of the supplementary motor area (SMA) is associated with transient speech defects. We investigated whether SMA laterality correlates with postoperative speech defects.

MATERIALS AND METHODS

The authors reviewed 17 patients with SMA-area lesion resection and preoperative language fMRI. SMA laterality was calculated by comparison of voxel activation in paired SMAs by hand-drawn regions of interest (ROIs) (drawn by a neuroradiologist), and compared with qualitative assessment by two neuroradiologists. Postoperative speech defects before and after surgery were assessed by chart review.

RESULTS

Six patients developed new speech defects that resolved within several months. Two of the patients had a pre-existing speech defect that had developed after prior SMA-area surgery. All these patients had left-sided lesions, while none of the four patients with a right-sided lesion developed a speech defect. Neuroradiologists' assessment of SMA laterality agreed with ROI calculation for the SMAs that were lateralized. However, for the SMAs in the "codominant" range by ROI, the neuroradiologists felt that all but one of the cases clearly lateralized, with the exception deemed indeterminate or codominant. No correlation between laterality of SMA and speech defect was identified. Twelve patients showed lateralization contralateral to the lesion.

CONCLUSIONS

fMRI lateralization does not correlate with transient speech defects that developed from SMA-area surgery. Qualitative/visual assessment of SMA laterality was superior to ROI calculation because of the close proximity and possible overlap of signal from midline SMA. A majority of patients showed SMA lateralization contralateral to the SMA lesion.

Incidence of local in-brain progression after supramarginal resection of cerebral metastases

BACKGROUND

Microsurgical circumferential stripping of intracerebral metastases is often insufficient in achieving local tumor control. Supramarginal resection may improve local tumor control.

METHODS

A retrospective analysis was performed for patients who underwent supramarginal resection of a cerebral metastasis by awake surgery with intraoperative cortical and subcortical stimulation, MEPs, and SSEPs. Supramarginal resection was achieved by circumferential stripping of the metastasis and additional removal of approximately 3 mm of the surrounding tissue. Pre- and postsurgical neurological status was assessed by the NIH Stroke Scale. Permanent deficits were defined by persistence after 3-month observation time.

RESULTS

Supramarginal resection of cerebral metastases in eloquent brain areas was performed in 34 patients with a mean age of 60 years (range, 33-83 years). Five out of 34 patients (14.7%) had a new transient postoperative neurological deficit, which improved within a few days due to supplementary motor area (SMA) syndrome. Five out of 34 patients (14.7%) developed a local in-brain progression and nine patients (26.4%) a distant in-brain progression.

CONCLUSIONS

Supramarginal resection of cerebral metastases in eloquent locations is feasible and safe. Safety might be increased by intraoperative neuromonitoring. The better outcome in the present series may be entirely based on other predictors than extend of surgical resection and not necessarily on the surgical technique applied. However, supramarginal resection was safe and apparently did not lead to worse results than regular surgical techniques. Prospective, controlled, and randomized studies are mandatory to determine the possible benefit of supramarginal resection on local tumor control and overall outcome.

Insights from the supplementary motor area syndrome in balancing movement initiation and inhibition

The supplementary motor area (SMA) syndrome is a characteristic neurosurgical syndrome that can occur after unilateral resection of the SMA. Clinical symptoms may vary from none to a global akinesia, predominantly on the contralateral side, with preserved muscle strength and mutism. A remarkable feature is that these symptoms completely resolve within weeks to months, leaving only a disturbance in alternating bimanual movements. In this review we give an overview of the old and new insights from the SMA syndrome and extrapolate these findings to seemingly unrelated diseases and symptoms such as Parkinson's disease (PD) and tics. Furthermore, we integrate findings from lesion, stimulation and functional imaging studies to provide insight in the motor function of the SMA.

Blood oxygen level dependent functional magnetic resonance imaging for presurgical planning

Functional magnetic resonance imaging (fMRI) has become a common tool for presurgical sensorimotor mapping, and is a significant preoperative asset for tumors located adjacent to the central sulcus. fMRI has changed surgical options for many patients. This noninvasive tool allows for easy display and integration with other neuroimaging techniques. Although fMRI is a useful preoperative tool, it is not perfect. Tumors that affect the normal vascular coupling of neuronal activity will affect fMRI measurements. This article discusses the usefulness of blood oxygen level dependent (BOLD) fMRI with regard to preoperative motor mapping.