Resection of gliomas in the precentral gyrus carries a risk of severe motor dysfunction. To prevent permanent, severe postoperative motor dysfunction, reliable intraoperative predictors of postoperative function are required. Since 2005, the authors have removed gliomas in the precentral gyrus with combined functional mapping and estimation of intraoperative voluntary movement (IVM) during awake craniotomy and transcortical motor evoked potentials (MEPs). The purpose of the current study was to evaluate whether intraoperative findings of combined monitoring of IVM during awake craniotomy and transcortical MEP monitoring were useful for predicting postoperative motor function of patients with gliomas in the precentral gyrus.
The current study included 30 patients who underwent resection of precentral gyrus gliomas during awake craniotomy from April 2000 to January 2018. All tumors were removed with monitoring of IVM during awake craniotomy and transcortical MEPs. Postoperative motor function was classified as stable or declined, with the extent of decline categorized as mild, moderate, or severe. We defined moderate and severe deficits were those that hindered daily life.
In 28 of 30 cases, available waveforms were obtained with transcortical MEPs. The mean extent of resection (EOR) was 93%. Relative to preoperative status, motor function 6 months after surgery was considered stable in 20 patients and was considered to show mild decline in 7, moderate decline in 2, and severe decline in 1. Motor function 6 months after surgery was significantly correlated with IVM (p = 0.0096), changes in transcortical MEPs (decline ≤ or > 50%) (p = 0.0163), EOR, and ischemic lesions on postoperative MRI. Six patients with no change in IVM showed stable motor function 6 months after surgery. Only 2 patients with a decline in IVM and a decline in MEPs ≤ 50% had a decline in motor function 6 months after surgery (18%; 2/11 patients), whereas 11 patients with a decline in IVM and a decline in MEPs > 50% had such a decline in motor function (73%; 8/11 patients) including 2 patients with moderate and 1 with severe deficits. Three patients with moderate or severe motor deficits showed the lowest MEP values (< 100 µV).
Combined judgment from monitoring of IVM during awake craniotomy and transcortical MEPs is useful for predicting postoperative motor function during removal of gliomas in the precentral gyrus. Maximum resection was achieved with an acceptable morbidity rate. Thus, these tumors should not be considered unresectable.
ABBREVIATIONSCMAP = compound muscle action potential; DWI = diffusion-weighted imaging; EOR = extent of resection; IVM = intraoperative voluntary movement; MEP = motor evoked potential; WHO = World Health Organization.
FujiiYMuragakiYMaruyamaTNittaMSaitoTIkutaS: Threshold of the extent of resection for WHO Grade III gliomas: retrospective volumetric analysis of 122 cases using intraoperative MRI. J Neurosurg129:1–92018
FukuiAMuragakiYSaitoTMaruyamaTNittaMIkutaS: Volumetric analysis using low-field intraoperative magnetic resonance imaging for 168 newly diagnosed supratentorial glioblastomas: effects of extent of resection and residual tumor volume on survival and recurrence. World Neurosurg98:73–802017
GemptJKriegSMHüttingerSBuchmannNRyangYMShibanE: Postoperative ischemic changes after glioma resection identified by diffusion-weighted magnetic resonance imaging and their association with intraoperative motor evoked potentials. J Neurosurg119:829–8362013
NoellSFeiglGCNarosGBarkingSTatagibaMRitzR: Experiences in surgery of primary malignant brain tumours in the primary sensori-motor cortex practical recommendations and results of a single institution. Clin Neurol Neurosurg136:41–502015
SaitoTMuragakiYMaruyamaTTamuraMNittaMTsuzukiS: Difficulty in identification of the frontal language area in patients with dominant frontal gliomas that involve the pars triangularis. J Neurosurg125:803–8112016
SaitoTMuragakiYTamuraMMaruyamaTNittaMTsuzukiS: Impact of connectivity between the pars triangularis and orbitalis on identifying the frontal language area in patients with dominant frontal gliomas. Neurosurg Rev[epub ahead of print] 2018
SaitoTTamuraMMuragakiYMaruyamaTKubotaYFukuchiS: Intraoperative cortico-cortical evoked potentials for the evaluation of language function during brain tumor resection: initial experience with 13 cases. J Neurosurg121:827–8382014
TakakuraTMuragakiYTamuraMMaruyamaTNittaMNikiC: Navigated transcranial magnetic stimulation for glioma removal: prognostic value in motor function recovery from postsurgical neurological deficits. J Neurosurg127:877–8912017