Swallowing difficulty is common in PD; in one small series of 13 patients, it was seen in 77% of patients (31). Potulska et al. (32) recruited 18 PD patients for detailed swallowing studies of which 13 had symptomatic dysphagia. All patients, including the five who had no swallowing complaints, had prolongation of esophageal bolus transport suggesting that autonomic impairment of swallowing may occur early. Patients who complained of dysphagia had abnormalities of the oral and pharyn-geal stages of swallowing. Since the oral phase of swallowing is under voluntary control, some have suggested that oral phase dysphagia is due to bradykinesia of the swallowing musculature. Evidence supporting this idea comes from a study of dys-kinetic and nondyskinetic patients showing that the dyskinetic ones had better swallowing efficiency, perhaps due to a more optimal dosage of levodopa (33). On the other hand, another study of 15 patients who had swallowing studies before and after a dose of levodopa showed minimal improvement following the drug, suggesting that the main problem is due to autonomic failure, not dopaminergic deficiency affecting skeletal muscle control (34).
Management of dysphagia in PD is entirely empiric. A recent review by the Cochrane Collaboration (35) uncovered no randomized trials dealing with non-pharmacological treatments for dysphagia in PD, and thus no recommendations for therapy could be made. Sharkawi et al. (36) performed an uncontrolled pilot study of the Lee Silverman Voice Treatment (LSVT) for dysphagia in PD, in which a modified barium swallow was done before and one month after LSVT in a group of eight patients. They reported that abnormalities of swallowing improved by 51% after therapy, principally by improving tongue base function during the oral and pharyngeal phases of swallowing. As this was a small uncontrolled study, further work is necessary to establish whether speech therapy is helpful for dysphagia in PD. Anecdotally, it has been suggested that patients with dysphagia employ the "chin-down" posture when swallowing (37) and consider adding thickeners to liquids before drinking. Since dysphagia is a significant risk factor for aspiration pneumonia (the cause of death in many patients with advanced PD), when this problem becomes severe, patients should consider placement of a percutaneous gastrostomy tube.
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