Intraoperative Neurophysiological Monitoring for Glioma Resection

Intraoperative neurophysiological monitoring (IONM) has become an indispensable element of modern glioma surgery, balancing the imperatives of maximal tumour removal with the preservation of neurological function. By continuously assessing the integrity of sensory and motor pathways during resection, IONM enables surgeons to delineate functional cortex and subcortical tracts in real time. Techniques such as direct cortical stimulation, motor and somatosensory evoked potentials, electromyography and electrocorticography each contribute unique insights into the operation’s impact on the brain‘s functional architecture. When applied alongside advanced neuroimaging and neuronavigation, these methods improve the surgeon’s ability to identify so-called eloquent areas, plan safe trajectories and detect impending injury before permanent deficits occur. Advances in stimulation paradigms, electrode technology and signal-processing algorithms have enhanced both the sensitivity and specificity of monitoring, reducing false alarms and refining decision thresholds. Awake craniotomy protocols, in particular, leverage patient feedback during language and motor mapping to achieve superior outcomes in critical regions. Collectively, IONM has demonstrated a key role in extending the boundaries of safe resection for gliomas, with clear benefits in postoperative neurological performance and overall quality of life.

Research from Nature Portfolio

Recent work has explored the incidence and determinants of intraoperative ischaemic events during high-grade glioma resection. Analysis of diffusion-weighted imaging in a large surgical cohort revealed that acute infarcts occur in over 10% of cases, with insular and temporal resections at particularly high risk. Patients who experienced intraoperative strokes exhibited significantly greater immediate and six-month motor deficits, as well as lower performance scores. Notably, real-time detection of ischaemia via neurophysiological decline in awake language tasks proved a sensitive indicator of vascular compromise. These findings highlight the need for optimised monitoring protocols and adjunctive strategies—such as intra-arterial flow assessment—to identify and mitigate intraoperative strokes, thereby improving functional outcomes and long-term survival.

Intraoperative Neurophysiological Monitoring for Glioma Resection publication trend

The graph below shows the total number of articles in intraoperative neurophysiological monitoring for glioma resection across all publications each year (not limited to Nature Index journals).

Technical terms

Intraoperative neurophysiological monitoring (IONM): Real-time assessment of neural pathway integrity during surgery, utilising electrical stimulation and recording techniques to prevent functional injury.

Motor evoked potentials (MEPs): Electrical responses recorded from muscles following stimulation of motor cortex or corticospinal pathways, used to assess motor tract function intraoperatively.

Direct cortical stimulation (DCS): Focal delivery of electrical pulses to the exposed cortical surface to map functional areas and evoke motor or language responses.

Transcranial electrical stimulation (TES): Non-invasive application of electrical currents through scalp electrodes to elicit MEPs, monitoring deeper white-matter tracts.

Somatosensory evoked potentials (SSEPs): Responses recorded from the cortex or spinal cord following peripheral nerve stimulation, used to track somatosensory pathway integrity.

Awake mapping: Surgical protocol in which patients remain conscious to perform language or motor tasks, allowing direct feedback during cortical stimulation.

Eloquent areas: Brain regions essential for basic functions such as speech, motor control or sensation, whose preservation is critical to postoperative quality of life.

References

1. Intraoperative Neuromonitoring During Resection of Gliomas Involving Eloquent Areas. Frontiers in Neurology (2021).
2. Technical Aspects of Motor and Language Mapping in Glioma Patients. Cancers (2023).
3. Transcranial versus direct electrical stimulation for intraoperative motor-evoked potential monitoring: Prognostic value comparison in asleep brain tumor surgery. Frontiers in Oncology (2022).
4. Risk factors and prognostic implications of surgery-related strokes following resection of high-grade glioma. Scientific Reports (2022).