Cerebral blood flow and neuropsychological asymmetries in unilateral stroke

This study sought to determine the degree of agreement between asymmetries of neuropsychological functioning and nine methods of quantifying asymmetries of regional cerebral blood flow.

The regional cerebral blood flow methods combined three markers of cerebral blood flow asymmetry (percent hemispheric difference, maximum percent probe-pair asymmetry, and number of probe-pair asymmetries) with three indexes of regional cerebral blood flow (fast compartment flow, initial slope index, and initial slope). Eleven patients with left hemispheric ischemic strokes and 13 with right hemispheric ischemic strokes were studied with the xenon-133 inhalation technique and neuropsychological tests.

Blind clinical judgments of neuropsychological asymmetry significantly correlated with all nine methods of cerebral blood flow asymmetry determination; correlations ranged from -0.42 to -0.77. Clinical judgment of asymmetry of neuropsychological functioning accurately predicted the hemisphere of lower flow in 71-92% of cases, depending on the method of cerebral blood flow asymmetry determination. Agreement between cerebral blood flow and neurobehavioral signs of asymmetry was greater for initial slope and initial slope index than for the fast flow index. The initial slope and initial slope index showed equally good agreement. The use of the number of asymmetrical probe pairs to detect cerebral blood flow asymmetries agreed less well with neurobehavioral asymmetry than did the other two markers studied.

Both the initial slope index and the initial slope measures of cerebral blood flow are useful in predicting neuropsychological asymmetries, especially when the magnitude of the asymmetry is taken into account.