TY - JOUR
T1 - Variability of intraoperative electrocortical stimulation mapping parameters across and within individuals
AU - Pouratian, Nader
AU - Cannestra, Andrew F.
AU - Bookheimer, Susan Y.
AU - Martin, Neil A.
AU - Toga, Arthur W.
PY - 2004/9
Y1 - 2004/9
N2 - Object. Electrocortical stimulation mapping is regarded as the gold standard of intraoperative mapping for predicting functional outcomes. Nevertheless, methodologies across institutions are inconsistent. Although many vary and maximize stimulation currents at each cortical site, some use a single current level to map the entire exposed cortex. The former comes at the cost of possibly inducing additional afterdischarge activity. The authors retrospectively reviewed their experience with intraoperative electrocortical stimulation mapping to characterize variability of both mapping and afterdischarge thresholds. Methods. Seventeen patients satisfied the study inclusion criteria. Significant variability in mapping thresholds was identified within individuals and across the patient population. Moreover, a statistically significant difference in mapping thresholds was demonstrated between the frontal and parietal/temporal lobes (p = 0.007, one-way analysis of variance). The authors report a surprisingly high incidence of afterdischarge during mapping, wide variability in afterdischarge thresholds within individuals and across the study population, and mapping thresholds regularly exceeding afterdischarge thresholds in neighboring cortex. Differences in afterdischarge thresholds across lobes only approached significance (p = 0.086). Conclusions. To maximize identification of eloquent cortices in some clinical situations, it may be advantageous to maximize currents at each cortical site regardless of adjacent afterdischarge threshold rather than to map the entire exposed cortex at a single current level. Moreover, the current findings highlight the need for electrocorticography during electrocortical stimulation mapping, both to identify when afterdischarges occur and to verify stimulation by recording stimulation artifacts. The advantages and limitations of maximizing currents at each cortical site as well as mapping at a single current level are discussed.
AB - Object. Electrocortical stimulation mapping is regarded as the gold standard of intraoperative mapping for predicting functional outcomes. Nevertheless, methodologies across institutions are inconsistent. Although many vary and maximize stimulation currents at each cortical site, some use a single current level to map the entire exposed cortex. The former comes at the cost of possibly inducing additional afterdischarge activity. The authors retrospectively reviewed their experience with intraoperative electrocortical stimulation mapping to characterize variability of both mapping and afterdischarge thresholds. Methods. Seventeen patients satisfied the study inclusion criteria. Significant variability in mapping thresholds was identified within individuals and across the patient population. Moreover, a statistically significant difference in mapping thresholds was demonstrated between the frontal and parietal/temporal lobes (p = 0.007, one-way analysis of variance). The authors report a surprisingly high incidence of afterdischarge during mapping, wide variability in afterdischarge thresholds within individuals and across the study population, and mapping thresholds regularly exceeding afterdischarge thresholds in neighboring cortex. Differences in afterdischarge thresholds across lobes only approached significance (p = 0.086). Conclusions. To maximize identification of eloquent cortices in some clinical situations, it may be advantageous to maximize currents at each cortical site regardless of adjacent afterdischarge threshold rather than to map the entire exposed cortex at a single current level. Moreover, the current findings highlight the need for electrocorticography during electrocortical stimulation mapping, both to identify when afterdischarges occur and to verify stimulation by recording stimulation artifacts. The advantages and limitations of maximizing currents at each cortical site as well as mapping at a single current level are discussed.
KW - Brain mapping
KW - Cortical stimulation
KW - Eloquent cortex
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U2 - 10.3171/jns.2004.101.3.0458
DO - 10.3171/jns.2004.101.3.0458
M3 - Review article
C2 - 15352604
AN - SCOPUS:4143122258
SN - 0022-3085
VL - 101
SP - 458
EP - 466
JO - Journal of neurosurgery
JF - Journal of neurosurgery
IS - 3
ER -