Voluntary saccades in disorders of the nigrostriatal (NS)-dopamine (DA) neuron

摘要

Objective Voluntary saccade (VS) is executed by the frontal eye field through two striatal pathways projecting to the basal ganglia projection to the superior colliculus. These pathways are modulated by the NS-DA neuron. We examined VS in the NS-DA neuron disorders and revealed particular abnormalities suggesting the pathophysiologies of these disorders. Method Visually guided saccades (VGS) and memory guided saccades (MGS) were examined. For both saccades, latencies, amplitudes and peak velocities were examined. For MGS, the frequency of saccades performed before the appearance of the target (frequency of MGS) and the frequency of saccades to the predicted cue (saccade to cue: SC) which is prohibited during the fixation period were evaluated. These values were correlated to those of age matched controls. Thirty-four patients with Segawa disease (SD), a dominantly inherited dopa-responsive dystonia caused by mutation of GCH-I gene, and 79 patients (6-12 years) with Tourette syndrome (TS) were subjected to this study. Results Patients with SD showed hypometria and prolongation of the latencies of both saccades, decrease in.the frequency of MGS, and increase in the frequency of the SC. Among SD those with action dystonia, showed marked abnormalities in MGS. These abnormalities, particularly of the SC were more marked in long lasting patients but just followed the age variations of the parameters of MGS. Patients with TS revealed longer latencies and hypometria in MGS, and decrease in the frequency of MGS. The frequency of SC was significantly lower in 23 younger group (6 < = 9 years) but higher in 56 older group (9 <= 12 years) than normal respectively. Conclusion These results revealed that in SD both the direct and indirect pathways were affected, but it was not a progressive change. SD with action dystonia and TS indirect pathways are affected and TS it aggravates with ages.