Variability of intraoperative electrostimulation parameters in conscious individuals: language cortex

Area of Science:

• Neurosurgery
• Neuroscience
• Brain Mapping

Background:

• Electrostimulation is vital for awake brain mapping during tumor resection.
• Methodologies for electrostimulation brain mapping vary significantly between institutions.

Purpose of the Study:

• To analyze electrostimulation brain mapping data to understand current intensity threshold variability.
• To determine how threshold variations affect the detection of essential language areas.

Main Methods:

• Prospective study of 100 adult patients undergoing left hemisphere tumor resection over 7 years.
• Standardized electrostimulation brain mapping protocol (controlled naming task, bipolar stimulation) and electrocorticography were used.
• Data collected on current intensity thresholds, response types, and detected area sizes.

Main Results:

• Minimum stimulation thresholds varied widely (1.5-9 mA), with 13.5% requiring >6 mA.
• Thresholds varied within patients (22%), and higher intensities altered response type (4.5%) and area size.
• Detected language sites were small (<20 mm² in 50%), with size dependent on stimulation intensity.

Conclusions:

• Intrasubject and intersubject variations in thresholds and response characteristics can complicate electrostimulation brain mapping interpretation.
• Using varied stimulation intensities up to maximum safe currents is recommended to optimize language area identification.
• Refined mapping techniques can improve clinical outcomes and scientific data from these procedures.