Cerebellar sensory processing alterations impact motor cortical plasticity in Parkinson's disease: clues from dyskinetic patients.

The plasticity of primary motor cortex (M1) in patients with Parkinson's disease (PD) and levodopa-induced dyskinesias (LIDs) is severely impaired. We recently reported in young healthy subjects that inhibitory cerebellar stimulation enhanced the sensorimotor plasticity of M1 that was induced by paired associative stimulation (PAS). This study demonstrates that the deficient sensorimotor M1 plasticity in 16 patients with LIDs could be reinstated by a single session of real inhibitory cerebellar stimulation but not sham stimulation. This was evident only when a sensory component was involved in the induction of plasticity, indicating that cerebellar sensory processing function is involved in the resurgence of M1 plasticity. The benefit of inhibitory cerebellar stimulation on LIDs is known. To explore whether this benefit is linked to the restoration of sensorimotor plasticity of M1, we conducted an additional study looking at changes in LIDs and PAS-induced plasticity after 10 sessions of either bilateral, real inhibitory cerebellar stimulation or sham stimulation. Only real and not sham stimulation had an antidyskinetic effect and it was paralleled by a resurgence in the sensorimotor plasticity of M1. These results suggest that alterations in cerebellar sensory processing function, occurring secondary to abnormal basal ganglia signals reaching it, may be an important element contributing to the maladaptive sensorimotor plasticity of M1 and the emergence of abnormal involuntary movements.

Gender influence on selection and outcome of deep brain stimulation for Parkinson's disease.

BACKGROUND: Gender differences exist in Parkinson's disease (PD), both in clinical manifestations and response to medical treatment. We investigated whether gender differences occur in the clinical characteristics of patients selected for bilateral subthalamic nucleus deep brain stimulation (STN DBS) or in the outcome when resource limits influence treatment choices made by patients. MATERIALS AND METHODS: Fifty-one consecutive patients were evaluated 1 month before, and 12 months after bilateral STN DBS. All patients were rated using Unified Parkinson's Disease Rating Scale, Parkinson's Disease Quality of Life (PDQL) Scale, Addenbrooke's Cognitive Examination and Beck Depression Inventory. RESULTS: Pre-operative characteristics did not differ between the genders except for lower doses of drugs (P = 0.03), worse emotional scores in PDQL (P = 0.01) and worse depression (P = 0.03) in women. There was no gender difference in the surgical outcome, except a lesser reduction of dopaminergic drugs in women. Depression and quality of life (QOL) improved equally well in women and men. CONCLUSION: Bilateral STN DBS is equally efficacious in both genders as a treatment for motor complications of PD and for improving QOL. Women are likely to be undertreated because of more severe dyskinesia and may experience less emotional well-being, and could therefore potentially benefit from earlier surgical treatment.