Hippocampal memory function as reflected by the intracarotid sodium methohexital Wada test

Area of Science:

• Neurology
• Neurosurgery
• Neuropsychology

Background:

• The intracarotid amobarbital procedure (IAP) is standard for assessing memory lateralization before epilepsy surgery.
• Drug shortages necessitated the use of sodium methohexital in the intracarotid methohexital procedure (IMP) as an alternative to amobarbital.
• Understanding the comparative efficacy of IAP and IMP is crucial for accurate pre-surgical memory assessment.

Purpose of the Study:

• To compare memory lateralization scores between the intracarotid amobarbital procedure (IAP) and the intracarotid methohexital procedure (IMP).
• To evaluate the predictive value of both procedures for post-surgical memory changes.
• To determine the impact of anesthetic agents on Wada testing results.

Main Methods:

• Retrospective analysis of Wada testing scores from 32 patients undergoing IAP and 20 patients undergoing IMP.
• Comparison of ipsilateral and contralateral memory scores between IAP and IMP groups.
• Correlation of Wada testing memory scores with standard neuropsychological memory test results.

Main Results:

• No significant difference in contralateral memory scores (first injection) between IAP and IMP.
• Significant differences in ipsilateral memory scores (second injection) between IAP and IMP (P=0.01), with IMP showing higher ipsilateral memory reserve.
• IAP scores demonstrated a stronger correlation with standard neuropsychological memory tests than IMP scores.

Conclusions:

• The choice of anesthetic agent in Wada testing can influence lateralized memory assessment.
• IMP may overestimate ipsilateral memory reserve compared to IAP, potentially affecting predictions of post-surgical amnesia.
• Further investigation is warranted to refine the use of IMP in pre-epilepsy surgery evaluations.