[Clinical pathophysiology of parkinsonian symptoms: from experiences of stereotaxic surgery]

Pathophysiological mechanisms of major symptoms of Parkinson's disease are discussed from experiences of stereotaxic surgery. Tremor completely disappears by a lesion in the ventral intermediate nucleus(Vim) which receives proprioceptive sense from the periphery. Rigidity is alleviated by a lesion in the globus pallidus(GP) and the ventral lateral nucleus(VL) equally. Since GP projects to the prefrontal motor cortex via VL, surgery to either of those structures causes the same result. Akinesia is classified into three types: secondary akinesia, primary akinesia, and akinesia due to psychomotor dysfunction. Gradual spread of neuronal degeneration within the substantia nigra pars compacta may explain the progression of akinesia. Psychological or psychiatric disorder becomes major symptom in the late stage. Posteroventral pallidotomy may change emotional state in some cases by influencing the limbic motor circuit.