LOCAL CEREBRAL BLOOD-FLOW IN MOTOR-NEURON DISEASE - CORRELATION WITH CLINICAL FINDINGS

Local cerebral blood flow (CBF) measured by xenon-enhanced CT was corr elated with the clinical findings in 21 patients with motor neuron dis ease (mean +/- SD age, 60 +/- 10 years). In 11 patients, CBF was also measured after intravenous injection of 2 mg thyrotropin releasing hor mone (TRH). There were no significant differences in CBF of the cerebr al cortex, basal ganglia, thalamus, and subcortical white matter with respect to age, duration of illness, or presence (n = 9) or absence (n = 12) of bulbar palsy. In patients with upper motor neuron disturbanc e (n = 10), however, local CBF in the frontal cortex was significantly lower (p < 0.05) than in those without it (n = 11). Within the fronta l cortex; CBF reduction was marked in the upper posterolateral part (p < 0.05) that included the motor and premotor areas. Intravenous admin istration of TRH did not significantly alter the local CBF in any of t he brain regions examined. An additional patient with motor neuron dis ease and severe dementia showed marked CBF reduction in the frontal lo be, which was in common with but much greater than the reduction in th ose exhibiting subcortical dementia (e.g., progressive supranuclear pa lsy). We conclude that in motor neuron disease patients with upper mot or neuron involvement, the selective reduction of CBF in brain regions that include primary motor and premotor areas may reflect functional disturbance or neuronal degeneration in these regions. The amelioratin g effect of TRH in patients with motor neuron disease, if any, appears not to be related to increases in local CBF or activation of brain fu nction.