FMRI reveals functional cortex in a case of inconclusive Wada testing.
OBJECTIVE
The intracarotid amobarbital test (Wada test) currently represents the gold standard for preoperative lateralization of hemispheric dominance. Here, we report an epileptic patient with a longstanding extended lesion of the left hemisphere showing absence of motor and speech dysfunction with left carotid amobarbital injection, but tetraplegia and speech arrest with right carotid injection interpreted as a neuroplastic shift of motor and language functions to the right hemisphere. In contrast to the Wada results, motor functional magnetic resonance imaging (fMRI) showed a strong left hemispheric activation with right hand movements.


METHODS
Right and left hand motor fMRI was performed. FMRI results and neurophysiological information obtained by motor and sensory evoked potential measurements were compared with the Wada test results.


RESULTS
Initial interpretation of neuroplastic shifts of intrinsic left hemisphere functions to the right brain was revised after fMRI results which were confirmed by motor and sensory evoked potentials.


CONCLUSIONS
As motor inactivation usually is thought to be the most robust feature of the Wada test, this case demonstrates that fMRI may reveal residual functional cortex in cases of inconclusive Wada results.
Lanzenberger
Rupert
R
Study Group Clinical fMRI at the Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
Wiest
Gerald
G
Geissler
Alexander
A
Barth
Markus
M
Ringl
Helmut
H
Wöber
Christian
C
Gartus
Andreas
A
Baumgartner
Christoph
C
Beisteiner
Roland
R
D000328:Adult; D000654:Amobarbital / Q000494:pharmacology; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology*; D004292:Dominance, Cerebral / Q000502:physiology*; D004828:Epilepsies, Partial / Q000503:physiopathology; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D008279:Magnetic Resonance Imaging
D006993:Hypnotics and Sedatives; D000654:Amobarbital