AWARENESS OF AND MEMORY FOR ARM WEAKNESS DURING INTRACAROTID SODIUM AMYTAL TESTING

The traditional association between anosognosia for hemiplegia and the right hemisphere was investigated ir? 31 patients with unilateral tem poral lobe pathology during intracarotid sodium amytal testing (ISA) b efore epilepsy surgery. Recall of arm weakness was examined by questio ning at the end of the test, when memory for items presented during th e hemiplegia was also examined. Significantly more patients were amnes ic for left arm weakness than for right. Amnesia for right arm weaknes s (and speech arrest) was significantly associated with pathology in t he temporal lobe on the non-injected side and with impaired recognitio n of the memory items. Amnesia for left arm weakness was independent o f both. Examination of cases where injection was contralateral to a he misphere without pathology, and which showed normal memory capacity un der ISA conditions, revealed that 87% recalled right arm weakness, but only 22% recalled left arm weakness. Awareness of arm weakness during left hemiplegia was examined in nine patients. Five of them were not aware of the weakness. Three of the four others could not subsequently recall it. By inference from the generally unimpaired recall of right arm weakness, following left hemisphere inactivation by amytal, an in tact right hemisphere is capable of both recognizing right arm weaknes s and mediating its subsequent recall. In contrast the left hemisphere was aware of left arm weakness only in similar to 50% of cases and ev en when there had been awareness usually could not mediate its subsequ ent recall. The suggestion is made that the right hemisphere may have a specific mnestic function for arm weakness, and presumably for hemip legia, additional to the gnostic function.