Treatment of blepharospasm with levodopa.

Mechanism of production of Parkinsonian symptoms The clinical features that result when the 'extrapyramidal' motor system is involved in disease are often highly characteristic, but unfortunately not yet well understood. Explanation of symptoms of Parkinson's disease is difficult not only because of their complexity but also by difficulties in interpreting the pathological material. There are few pathological changes, the most consistent appearing to be the loss of nerve cells from the substantia nigra and of myelinated fibres from the globus pallidus and depletion of dopamine in the globus pallidus. However, it is important that the clinical features are recognized before attempts are made to understand the underlying mechanism of production of symptoms in the light of present knowledge. One of the commonest and earliest symptoms of parkinsonism is tremor consisting of rhythmic alternating movements of opposing muscle groups with a frequency of about 6/sec. The tremor is usually confined to one hand or less commonly the foot and