Gastrointestinal manifestations of Parkinson's disease

Gastrointestinal involvement is common in Parkinson's disease (PD) and symptoms related to gastrointestinal dysfunction may feature prominently, impact on quality of life and compromise nutrition. While all components of the gastrointestinal tract may be involved, drooling, dysphagia and constipation are the most common symptoms. Various factors contribute to the etiology of gastrointestinal dysfunction in PD and include the involvement of skeletal muscles in the oropharynx, pelvic floor and external anal sphincters in the motor dysfunctions that typify this movement disorder, an associated autonomic neuropathy and the presence of Lewy bodies and other pathological hallmarks of PD in the enteric nervous system. In assessing gastrointestinal symptoms in PD, one must also be mindful of the effects of anti-Parkinsonian medications. The latter observation together with reports of the development of gastrointestinal symptoms, such as constipation, decades before the onset of the classical neurological features of the disorder led to the hypothesis, that, in some individuals, the PD process may originate in the gut and ascend via the vagus nerve to the central nervous system. We review the clinical presentation, prognosis and complications of common gastrointestinal problems in PD and present an approach to their assessment and management. Interactions between gastrointestinal issues, the typical motor features of PD and common co-morbidities are discussed. For several of these problems, the evidence base for therapies directed specifically to the PD patient is thin and reliance continues to be placed on data derived from the management of these symptoms and syndromes in non-PD patients.