|Budget Amount *help
¥7,100,000 (Direct Cost : ¥7,100,000)
Fiscal Year 1995 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1994 : ¥6,200,000 (Direct Cost : ¥6,200,000)
Posteroventral pallidotomy (PVP) was carried out by image-guided stereotactic procedure in 275 patients with Parkison's disease (PD) , 21 with various types of idiopathic dystonia and 9 patients with other involuntary movements. In majority of the PD patients, bradykinesia, postural instability, rigidity, tremor and dyskinesia were markedly improved after PVP.Some PD patients exhibiting marked initial hegitation of gait minimum signs of rigidity and tremor (pure kinesia type) did not benefit from PVP.Except for spasmodic torticollis, PVP reduced dystonic contraction especially in the body axis and lower limbs. Younger patients with torsion dystonia of onset age before 10 years benefitted dramatically from PVP.Microrecording in Parkinsonian patients revealed that the spontaneous activity was minimum in the striatum and moderate in the external segment of the globus pallidus (GPe) , and it increased significantly in the internal segment (GPi). Most neurons in the GPi showed tonic activit
y discharging in high rates of 80-150 spikes per second. The background activity in the dystonic patients was moderate equally in the striatum and globus pallidus. Some pallidal neurons were potentiated relating to voluntary or involutary movements. There was a roughly arranged somatotopy of the movement-related neurons in the GPi.
The tonic overactivity in the GPi in PD patients is compatible with the experimental findings in MPTP-induced disorder in monkey models, and leads to excessive inhibition of the thalamic motor nuclei and, via the pallido-tegmental bundle, the pedunculopontine nucleus, underlying akinesia and postural abnormality. The dramatic therapeutic effects of PVP reveal the significance of pallidal inhibition of the mesencephalic locomotion reticulo-spinal pathway. Good results of PVP were obtained for dystonic symptoms, especiaaly in the case of proximal rather than distal symptoms, as compared with thalamotomy. The clinical results indicate that the mechaniam of dystonia in pediatric case implicates the descending pallido-reticulo-spinal pathway that may develp earlier than the ascending pallido-thalamo-cortical pathway. To interpret quantitative changes of the background activity in the basal ganglia, we need to collect further data in dystonia as well as in other movement disorders. Less