Targeting Primary Motor Cortex (M1) Functional Components in M1 Gliomas Enhances Safe Resection and Reveals M1 Plasticity Potentials

Abstract

Primary-Motor-Cortex (M1) hosts two functional components, at its posterior and anterior borders, being the first faster and more excitable. We developed a mapping-technique for M1 components identification and determined their functional cortical-subcortical architecture in M1 gliomas and the impact of their identification on tumor resection and motor performance. A novel advanced mapping technique was used in 102 tumors within M1 or CorticoSpinal-Tract to identify M1-two components. High-Frequency-stimulation (2–5 pulses) with an on-line qualitative and quantitative analysis of motor responses was used; the two components’ cortical/subcortical spatial distribution correlated to clinical, tumor-related factor and patients’ motor outcome; a cohort treated with standard-mapping was used for comparison. The two functional components were always identified on-line; in tumors not affecting M1, its functional segregation was preserved. In M1 tumors, two architectures, both preserving the two components, were disclosed: in 50%, a normal cortical/subcortical architecture emerged, while 50% revealed a distorted architecture with loss of anatomical reference and somatotopy, not associated with tumor histo-molecular features or volume, but with a previous treatment. Motor performance was maintained, suggesting functional compensation. By preserving the highest and resecting the lowest excitability component, the complete-resection increased with low morbidity. The real-time identification of two M1 functional components and the preservation of the highest excitability one increases safe resection, revealing M1 plasticity potentials.

Surgical treatment of gliomas in motor zone under control of neurophysiological monitoring

“…В то же время существуют рекомендации, апеллирующие к повышенному риску развития судорожных приступов при низкочастотной стимуляции и советующие применять во всех случаях параметры М. Taniguchi [12]. Кроме того, возможно переключение этих параметров при кортикальной и субкортикальной стимуляции [13,14].…”

Technical Aspects of Motor and Language Mapping in Glioma Patients

“…Traditionally, high-frequency monopolar stimulation is administered as a monophasic wave pulse in trains of 5 (0.5 ms pulse duration, 1–4 ms interstimulation interval, 0–20 mA); however, more recently, reduced trains of 1 to 2 [ 51 , 66 ] have demonstrated added utility as well. Rossi et al directly compared these two protocols and identified tumor subgroups in which shorter trains may offer additional insight.…”

“…Rossi et al directly compared these two protocols and identified tumor subgroups in which shorter trains may offer additional insight. In tumors outside of the primary motor cortex and cortical spinal tracts, those only affecting the cortical spinal tracts, or those originating within the primary motor cortex with normal cortical architecture, ‘train of 2’ stimulation better segregated the anterior and posterior regions of the primary motor cortex—a distinction that may aid in maximizing EOR while preserving long-term function [ 66 ]. In addition, only the two trains of stimulation identified function-free zones in primary motor cortex tumors with distorted cortical architecture.…”

Surgical Treatment of Glioblastoma: State-of-the-Art and Future Trends

“…This enables the surgeon to adjust the speed of resection when approaching the corticospinal tract [135,137]. Rossi et al developed an advanced mapping technique used for tumors located within the primary motor cortex or subcortical motor pathways [138]. They used high-frequency stimulation (HF-To5 and HF-To2) in the exposed motor cortex in order to establish the safe entry zone for the corticectomy [138].…”