Topographical risk factor analysis of new neurological deficits following precentral gyrus resection

Surgery for Epilepsy Involving Rolandic and Perirolandic Cortex: A Case Series Assessing Complications and Efficacy

BACKGROUND

Surgical removal of lesions around the rolandic cortex remains a challenge for neurosurgeons owing to the high risk of neurological deficits. Evaluating the risk factors associated with motor deficits after surgery in this region may help reduce the occurrence of motor deficits.

OBJECTIVE

To report our surgical experience in treating epileptic lesions involving the rolandic and perirolandic cortices.

METHODS

We performed a single-center retrospective review of patients undergoing epilepsy surgeries with lesions located in the rolandic and perirolandic cortices. Patients with detailed follow-up information were included. The lesion locations, resected regions, and invasive exploration techniques were studied to assess their relationship with postoperative motor deficits.

RESULTS

Forty-one patients were included. Twenty-three patients suffered from a transient motor deficit, and 2 had permanent disabilities after surgery. Six patients with lesions at the posterior bank of the precentral sulcus underwent resection, and 5 experienced short-term motor deficits. Two patients with lesions adjacent to the anterior part of the precentral gyrus, in whom the adjacent precentral gyrus was removed, experienced permanent motor deficits. Lesions located at the bottom of the central sulcus and invading the anterior bank of the central sulcus were observed in 3 patients. The patients did not experience permanent motor deficits after surgery.

CONCLUSION

The anterior bank of the central sulcus is indispensable for motor function, and destruction of this region would inevitably cause motor deficits. The anterior bank of the precentral gyrus can also be removed without motor impairment if there is a preexisting epileptogenic lesion.

Dexmedetomidine inhibits unstable motor network in patients with primary motor area gliomas

Background: Sedative agents such as dexmedetomidine have been found to transiently exacerbate or unmask limb motor dysfunction in patients with eloquent area brain gliomas. The present study aims to investigate whether dexmedetomidine can inhibit motor plasticity in patients with glioma via fMRI.

Methods: 21 patients with brain glioma were prospectively recruited between September 2017 and December 2018. Patients were classified into pre-M1 (primary motor cortex) group (n=9), post-M1 group (n=6), and non-eloquent group (control group) (n=6) according to the tumor position related to M1. The hand movement task-fMRI and resting state fMRI (rs-fMRI) were performed before and after sedation using dexmedetomidine. The lateralization index (LI) of activation voxels and magnitude and the functional connectivity (FC) of motor network were compared before and after sedation and among different groups.

Results: Permanent postoperative motor deficit of the upper limb was found in 5 of 6 patients in the pre-M1 group, and none in other groups (P < .01). Task-fMRI showed the LI of activation volume and activation magnitude at M1 significantly increased only in the pre-M1 group after sedation (P < .05). Rs-fMRI showed 60.0% (27 of 45) FCs of motor network decreased in pre-M1 group after sedation (p[FDR] < .05); whereas there was no FC reduction in post-M1 and control groups (p[FDR] > .05).

Conclusions: In patients with eloquent area gliomas, dexmedetomidine can inhibit the unstable compensative motor plasticity on both task- and rs-fMRI. fMRI may be a promising method for elucidating the effect of sedative agents on motor plasticity.

Presurgical Localization of the Primary Sensorimotor Cortex in Gliomas : When is Resting State FMRI Beneficial and Sufficient?

PURPOSE

Functional magnetic resonance imaging (fMRI) has an established role in neurosurgical planning; however, ambiguity surrounds the comparative value of resting and task-based fMRI relative to anatomical localization of the sensorimotor cortex. This study was carried out to determine: 1) how often fMRI adds to prediction of motor risks beyond expert neuroradiological review, 2) success rates of presurgical resting and task-based sensorimotor mapping, and 3) the impact of accelerated resting fMRI acquisitions on network detectability.

METHODS

Data were collected at 2 centers from 71 patients with a primary brain tumor (31 women; mean age 41.9 ± 13.9 years) and 14 healthy individuals (6 women; mean age 37.9 ± 12.7 years). Preoperative 3T MRI included anatomical scans and resting fMRI using unaccelerated (TR = 3.5 s), intermediate (TR = 1.56 s) or high temporal resolution (TR = 0.72 s) sequences. Task fMRI finger tapping data were acquired in 45 patients. Group differences in fMRI reproducibility, spatial overlap and success frequencies were assessed with t‑tests and χ²-tests.

RESULTS

Radiological review identified the central sulcus in 98.6% (70/71) patients. Task-fMRI succeeded in 100% (45/45). Resting fMRI failed to identify a sensorimotor network in up to 10 patients; it succeeded in 97.9% (47/48) of accelerated fMRIs, compared to only 60.9% (14/23) of unaccelerated fMRIs ([Formula: see text](2) = 17.84, p < 0.001). Of the patients 12 experienced postoperative deterioration, largely predicted by anatomical proximity to the central sulcus.

CONCLUSION

The use of fMRI in patients with residual or intact presurgical motor function added value to uncertain anatomical localization in just a single peri-Rolandic glioma case. Resting fMRI showed high correspondence to task localization when acquired with accelerated sequences but offered limited success at standard acquisitions.

NTMS mapping of non-primary motor areas in brain tumour patients and healthy volunteers

OBJECTIVE

Navigated transcranial magnetic stimulation (nTMS) has been increasingly used for presurgical cortical mapping of the primary motor cortex (M1) but remains controversial for the evaluation of non-primary motor areas (NPMA). This study investigates clinical and neurophysiological parameters in brain tumour patients and healthy volunteers to decide whether single-pulse biphasic nTMS allows to reliably elicite MEP outside from M1 or not.

MATERIALS AND METHODS

Twelve brain tumour patients and six healthy volunteers underwent M1 nTMS mapping. NPMA nTMS mapping followed using 120% and 150% M1 resting motor threshold (RMT) stimulation intensity. Spearman's correlation analysis tested the association of clinical and neurophysiological parameters between M1 and NPMA mapping.

RESULTS

A total of 88.81% of nTMS stimulations in NPMA in patients/83.87% in healthy volunteers in patients/83.87% in healthy volunteers did not result in MEPs ≥ 50 μV. Positive nTMS mapping in NPMA correlated with higher stimulation intensity and larger M1 areas in patients (120% M1 RMT SI p = 0.005/150% M1 RMT SI p = 0.198).

CONCLUSION

Our findings indicate that in case of positive nTMS mapping in NPMA, MEPs originate mostly from M1. For future studies, MEP parameters and TMS coil rotation should be studied closely to assess the risk for postoperative motor deterioration.

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.