WADA MEMORY ASYMMETRY AS A PREDICTOR OF SURGICAL OUTCOME AND VERBAL MEMORY CHANGE AFTER TEMPORAL LOBECTOMY
Abstract number :
2.420
Submission category :
Year :
2003
Submission ID :
1064
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Heidi E. Majors, Paul A. Garcia, Scott Winstanley, Kent Soo Hoo, Stephen T.C. Wong, Nicholas M. Barbaro, Kenneth D. Laxer, John A. Walker Neurology, University of California, San Francisco, San Francisco, CA; Radiology, University of California, San Franc
The intracarotid amytal (Wada) test can be used to evaluate the memory capacity of each hemisphere prior to temporal lobectomy (TL). Most patients demonstrate better memory with amytal injection of the hemisphere containing the seizure focus (expected asymmetry, EA), but a substantial minority show better memory with injection of the contralateral side (unexpected asymmetry, UA). A recent series of 18 patients (Sabsevitz [italic]et al.[/italic], [italic]Epilepsia[/italic] 42(11)1408-1415) suggested that UA was associated with greater decline in verbal memory and worse surgical outcome after left TL.
Drawing from our centralized epilepsy database, we examined memory and surgical outcome in 97 left and 105 right anterior temporal lobectomy patients. Surgical treatment consisted of resection of anterior temporal cortex, amygdala and between 2.5 and 3.5 cm of hippocampus. Intraoperative ECoG and, when applicable, speech mapping were used as aids in determining the extent of lateral temporal resection. To measure memory, we used the score on the post-distraction trial (Trial 6) of the Rey Auditory Verbal Learning Test, and to measure surgical outcome, we used Engel Class (1 or 2-4) at last follow-up (time to follow-up range = 3 months to 15 years; mean 34 months).
Comparing contralateral to ipsilateral Wada memory scores, 38% of left TL patients and 9.5% of right TL patients had an UA (see Tables 1 and 2). There was no correlation between the direction and degree of memory asymmetry and postoperative verbal memory change score for left (r = 0.016, p [gt] 0.05) or right (r = 0.090, p [gt] 0.05) TL patients. In left TL patients, the direction of Wada memory asymmetry failed to predict surgical outcome (Fisher[rsquo]s exact test, two-sided, p = 0.66). However, for right TL patients, UA was a predictor of incomplete seizure control (Fisher[rsquo]s exact test, two-sided, p = 0.03).
The results in this large series support our clinical experience that Wada memory asymmetry fails to predict postoperative change in verbal memory. UA is uncommon in right TL patients and it may signal an increased risk of poor surgical outcome. Perhaps because language confounds the assessment of memory during the language dominant injection, UA is more common in left TL patients and does not seem to represent a risk for poor seizure control. [table1][table2]
[Supported by: Epilepsy database supported by NINDS RO1-NS36007 and NLM R29-LM06300, both to STCW. Also supported in part by NIH R01-NS31966 to KDL. ]