Academic Editor: Gernot Riedel
Background: Cortico-cortical evoked potentials (CCEPs) have been used
to map the frontal (FLA) and parietal (PLA) cortical regions related to language
function. However, they have usually been employed as a complementary method
during sleep-awake surgery. Methods: Five male and two female patients
received surgery for tumors located near language areas. Six patients received
general anesthesia and the sleep-awake method was used for patients with tumors
located near the cortical language areas. We performed motor and somatosensory
mapping with CCEPs to identify language areas and we monitored responses during
surgery based on the mapping results. Electrocorticography was performed
throughout the surgery. Single pulses of 1 ms duration at 5–20 mA were delivered
by direct cortical stimulation using one grid at one region (e.g., FLA) and then
recording using a second gird at another area (i.e., PLA). Next, reversed
stimulation (from PLA to FLA) was performed. The charge density for electrical
stimulation was computed. Sensibility, specificity, predictive positive values,
and predicted negative values were also computed for warning alterations of
CCEPs. Results: Gross tumor resection was achieved in four cases. The
first postsurgical day showed language alterations in three patients, but one
year later six patients remained asymptomatic and one patient showed the same
symptomatology as previously. Seizures were observed in two patients that were
easily jugulated. CCEPs predicted warning events with high sensibility and
specificity. Postsurgical language deficits were mostly transitory. Although the
latency between frontal and parietal regions showed symmetry, the amplitude and
the relationship between amplitude and latency were different for FLA than for
PLA. The charge density elicited by CCEPs ranged from 442 to 1768