Surgical treatment of low-grade gliomas involving motor areas

Abstract

Objective To explore the possibility and strategy of maximally removal of low-grade gliomas which involved the motor areas on the premise of protecting the patient' motor function.Methods The neurosurgical plans and procedures of 30 patients with low-grade gliomas involving the motor areas in Beijing Tiantan Hospital from December 2011 to May 2013 were analyzed retrospectively.Preoperative head magnetic resonance imaging (MRI) was performed in all patients.A ω-shaped or inverted Ω-shaped hand-knob as a logo was used to confirm the precentral gyrus (primary motor area,M1).Intraoperative somatosensory evoked potential (SEP) was used to confirm the central sulcus,M1 and premotor area (PMA).MEP was used to monitor the function of motor pathway.The extent of tumor resection was evaluated by intraoperative B-mode ultrasound at the same time.Postoperative head MRI within 72 hours was used to evaluate the extent of tumor resection.The muscular power was determined instantly after waking up,2 weeks and 3 months following operation separately.Results The M1 was involved in 3 cases,the supplementary motor area (SMA) in 3,the PMA in 11,and the SMA and PMA were simultaneously involved in 13.Subtotal resection was achieved in 27 cases (90％) while partial resection in 3 (10％).The histological results of all patients revealed oligodendroglioma in 2 cases,astrocytoma in 9 and oligo-astrocytoma in 19.Preoperative muscle power was normal in 25 cases,4 of them had one hand less flexible and could not perform accurately,and 2 of them felt trample empty while walking,and 5 cases had grade Ⅳ muscle power.After the surgery,part of patients had transient muscle disorders.Three months after the surgery,muscle power was normal in 23 cases,9 of them had one hand less flexible and could not perform accurately,3 of them felt trample empty while walking.7 cases had grade Ⅲ-Ⅳ muscle power of upper or lower limbs.Conclusions Motor area is consisted of M1,PMA,SMA,corticonuclear tract and corticospinal tract started from them.The position of low-grade gliomas involving the motor areas should be confirmed accurately before surgery.Under the use of some technologies such as intraoperative electrophysiology,B-mode ultrasonography and delicate microneurosurgical techniques,subtotal resection of tumors without causing permanent motor deficits might be achieved. Key words: Primary motor area; Supplementary motor area; Premotor area; Low-grade glioma; Neurosurgical procedures