Name:
10.3171/2024.10.FOCVID24126
Description:
10.3171/2024.10.FOCVID24126
Thumbnail URL:
https://cadmoremediastorage.blob.core.windows.net/847dea88-7f58-4ab7-9130-96fbb32c53e1/videoscrubberimages/Scrubber_253.jpg
Duration:
T00H08M28S
Embed URL:
https://stream.cadmore.media/player/847dea88-7f58-4ab7-9130-96fbb32c53e1
Content URL:
https://cadmoreoriginalmedia.blob.core.windows.net/847dea88-7f58-4ab7-9130-96fbb32c53e1/5. 24-126.mp4?sv=2019-02-02&sr=c&sig=Sre7VAGXG61Fbm%2BpVUTrumHS1NXCDA3XInvJjuCnxz8%3D&st=2026-06-26T05%3A26%3A04Z&se=2026-06-26T07%3A31%3A04Z&sp=r
Upload Date:
2024-11-21T00:00:00.0000000
Transcript:
Language: EN.
Segment:0 .
[AUDIO LOGO]
SPEAKER: Clinical approaches and philosophies are widely heterogeneous with regard to intra-axial supratentorial glioma surgery. However, it's universally accepted that safe and maximal resection with the avoidance of significant ischemic or neurologic injury is considered the primary goal. Advances in electrophysiological mapping and monitoring techniques permit the objective measurement of eloquent motor and language cortical regions and accompanying white matter tracts to reduce the incidence of iatrogenic neurological injury in glioma surgery.
SPEAKER: Various electrophysiological biomarkers exist that can be reliably mapped and monitored in both awake and asleep craniotomy, which are often integrated in a multimodal fashion. Subject to the clinical indication, this usually consists of bipolar low-frequency direct cortico-subcortical stimulation for cognitive mapping, monopolar high-frequency direct cortico-subcortical stimulation for motor mapping, direct cortical motor evoked potentials via subdural electrode for continuous corticospinal tract monitoring, sensorimotor phase reversal for the functional delineation of pericentral anatomy, and electrocorticography or intracranial electroencephalography for the detection of afterdischarges associated with cortical stimulation or mapping of epileptogenic irritative zones.
SPEAKER: Recently, there have been increased interest in mapping and monitoring of the human arcuate fasciculus in awake and asleep settings, which represents an emerging frontier in neuro-oncology surgery, including the prospect of monitoring expressive language function under general anesthesia. Here we present our initial experience in exploring the feasibility and clinical utility of arcuate cortico-cortical evoked potentials in a 27-year-old female who presented with generalized seizure activity, auditory hallucinations, and baseline semantic paraphasias.
SPEAKER: Preoperative MRI revealed a suspected diffuse lower-grade glioma comprising the anterior and middle temporal lobe. The patient was scheduled for a hypnosis-assisted awake craniotomy with bipolar low-frequency cortico-subcortical stimulation with electrocorticography and arcuate fasciculus cortico-cortical evoked potentials. The patient's hypnotic state was established in the anesthetic bay by a senior consultant anesthetist with an extensive history in clinical hypnosis.
SPEAKER: This involved a series of mindfulness techniques as part of a prospective study we've initiated to explore electrophysiological biomarkers associated with cortical excitability changes and the subsequent impact on awake craniotomy compliance. The procedure was performed with the patient in the supine position with a lateral head tilt with the head fixated.
SPEAKER: Targets were applied via stereotactic navigation in addition to posterior margin, temporal stem, and temporal horn fence posting. Following craniotomy and durotomy, a four-channel subdural electrode was positioned towards the inferior frontal gyrus and pars triangularis. Another four-channel subdural electrode was introduced to the posterior superior temporal gyrus.
SPEAKER: Both electrodes were originally configured for electrocorticography recording during language mapping to mitigate the risk of intraoperative seizures. Extensive cortical mapping via bipolar direct cortico-subcortical stimulation then proceeded at 2 milliamps and increased in 1- milliamp intervals until there was evidence of speech and language disturbance, as indicated by the speech pathology team.
SPEAKER: Or if there were afterdischarge activity as recorded via electrocorticography. No such activity was recorded. Bipolar direct cortical stimulation towards the electrode near the inferior frontal gyrus was positive for speech arrests at 3 milliamps. This data would be used to optimize the electrode for CCEP stimulation. Optimization of arcuate CCEPs was performed in conjunction with Prof. Sedal and team's recent study.
SPEAKER: The surgical team recognized prior to optimization of signals that CCEP morphology would not impact surgical decision-making due to lack of clinical evidence relating to clinically significant morphological changes. CCEP stimulation was initially conducted very conservatively at low intensities such as 3 milliamps and ramped up progressively until 20 milliamps, where a positive N1, P1, N2 morphology was observed.
SPEAKER: Stimulation was conducted with two adjacent contacts of the stimulating strip in a bipolar stimulation configuration. In the video shown CCEP channel, well, CCEP1 refers to bipolar stimulation at channels 1 and 2, and CCEP3 refers to bipolar stimulation at channels 3 and 4. The CCEP recording electrode was configured in both bipolar and referential montages for analysis. For referential recordings, the contralateral mastoid was used as a reference.
SPEAKER: Stimulation was carried out with alternating monophasic square waves of constant current, single-pulse electrical stimulation with a pulse duration of 0.5 milliseconds, a stimulation intensity of 5 to 20 milliamps and a stimulation frequency of 1.1 hertz. The recordings were acquired with a hardware high-pass filter of 30 hertz, a hardware low-pass filter of 5 kilohertz, an epoch of 1,000 milliseconds, and a sampling rate of 20,000 hertz.
SPEAKER: Software filters were set at 10 for high-pass and 1,500 for low-pass, while the sensitivity was 50 to 300 microvolts per div and the sweep was 200 to 300 milliseconds. Trials of 30 averages each were established. As per Seidel et al.'s recent study, N1 was defined as a negative deflection occurring at a peak latency between approximately 10 and 30 milliseconds and with a duration of at least 10 milliseconds, as determined by visual inspection.
SPEAKER: Resection continued to the floor of the middle fossa and the temporal pole, resecting the entirety of the middle and inferior temporal gyri. A small portion of posterior superior temporal gyrus remained preserved at hemostasis. Medial temporal lobe structures were not resected. Histopathological findings returned, oligodendroglioma grade 2.
SPEAKER: There were no adverse effects associated with CCEP stimulation or recording, nor did the intermittent nature of testing bear any untoward effects on the patient during regular speech assessments. This is due to the reduced pulse width in comparison to classical bipolar low-frequency direct cortical stimulation, which contributes towards transient cognitive inhibition.
SPEAKER: Further investigation is required with regard to clinical significance criteria to examine whether the technique will join the electrophysiological armamentarium routinely endorsed in contemporary neuro-oncology surgery. However, network-level electrophysiological biomarkers such as the arcuate fasciculus CCEP may provide opportunities for asleep language mapping and monitoring in addition to other white matter networks associated with cognitive function, which is particularly encouraging for patients not indicated for awake craniotomy.
SPEAKER: Hypnosis-assisted craniotomy may also permit more extensive intraoperative language assessment, possibly in conjunction with electrophysiologic assessment of the hypnotic state via electrocorticography and evoked potentials.
Form Title Download
Form Title Bookmark
Form Title Share
Form Title Cite
