ABSTRACT
James Parkinson first described the tremor, rigidity and bradykinesia/akinesia that characterize the syndrome known as Parkinson’s disease. Most cases of Parkinson’s disease are caused by idiopathic degeneration of the nigrostriatal pathway. Atherosclerotic, toxic (e.g. related to antipsychotic drug treatment, manganese or carbon monoxide poisoning) and post-encephalitic cases also occur. Treatment of parkinsonism caused by antipsychotic drugs differs from treatment of the idiopathic disease, but other aetiologies are treated similarly to
● ● Spasticity 128 ● Chorea 129 ● Drug-induced dyskinesias 129
● Treatment of other movement disorders ● Myasthenia gravis 129 ● Alzheimer’s disease 131
the idiopathic disease. Parkinsonian symptoms manifest after loss of 80% or more of the nerve cells in the substantia nigra. The nigrostriatal projection consists of very fine nerve fibres travelling from the substantia nigra to the corpus striatum. This pathway is dopaminergic and inhibitory, and the motor projections to the putamen are more affected than either those to the cognitive areas or to the limbic and hypolimbic regions (Figure 21.1). Other fibres terminating in the corpus striatum include excitatory cholinergic nerves and noradrenergic and serotoninergic fibres, and these are also affected, but to varying extents, and the overall effect is a complex imbalance between inhibitory and excitatory influences.
