Guideline for the treatment of Parkinson's disease.

Parkinson's disease (PD) is a common neurodegenerative disorder that affects the central nervous system. It has a prevalence of about 3% in the age group over 60, and becomes increasingly common with advancing age, particularly affecting men. 1 The epidemiology of the condition is unknown in South Africa and limited in Africa, although it is thought to be commonest in people of Northern European origin. Although a number of genes have been implicated in the genesis of PD, the cause in the majority of patients remains unclear, especially given that the prevalence is highest in the elderly, whereas a clear genetic predisposition is best defined in those with disease of earlier onset. 2 The illness is progressive and associated with significant disability and there is no proven way of slowing or altering the course, although many of the symptoms are amenable to therapy. PD has traditionally been viewed predominantly as a disturbance of the motor system, manifesting with tremor and slowness. However, it is increasingly clear that so-called non-motor manifestations are associated with much of the morbidity. A revision of the neuropathology of PD has allowed for a new approach to the course of the illness. 3 A preclinical phase exists, which may be characterised by loss of the sense of smell and by REM sleep behaviour disorder (RBD). RBD is a condition in which the normal mechanisms of REM sleep are affected, as a result of which patients may act out their dreams, sometimes in a violent fashion. The motor manifestations of PD are typically noted when up to 80% of existing dopaminergic cells have been lost. There has been particular interest in this stage, since early intervention that results in a reduction in cell damage could potentially halt or slow the progression of the disease. As the disease advances there is progressive loss of dopaminergic cells, but other monoaminergic systems, such as the serotoninergic system, may also be affected, as well as other brainstem nuclei. PD is essentially a multisystem disease affecting many areas of the brain, ranging from the medulla to the cerebral cortex. The early stages of the disease are well known to be highly responsive to treatment. However, with increasing loss of dopaminergic and other cell groups there is a trend towards requirement of increasing amounts of dopamine. The development of motor fluctuations, while not inevitable, is a common problem. Motor fluctuations describe the situation …