Parkinson’s disease is the most common movement disorder in developed countries. Even with levodopa therapy the cause of death in such patients is commonly respiratory. Characteristic findings in such patients are a reduction in both maximal static inspiratory and expiratory pressures as well as maximal inspiratory and expiratory flows. Moreover, such patients are unable to generate a rapid rise in peak expiratory flow which may be important for a maximally effective cough, a finding consistent with the hypokinesia typical of the condition. These abnormalities were shown to be correctable in a substantial proportion of patients by the administration of apomorphine. Interestingly, patients with early Parkinson’s disease and normal respiratory muscle strength are markedly less able to perform repetitive bursts of respiratory muscle work than age matched controls. Problems in the coordination of activation of respiratory muscle also seem to be responsible for the dyspnoea which can occur in patients with dystonia.
Upper airway flutter is sometimes found on the flow volume loops of parkinsonian patients; this indicates upper airway dysfunction and sleep abnormalities might therefore be expected. Obstructive apnoeas are more common in parkinsonian patients, but a range of other abnormalities are also found which result in fragmented sleep architecture. In the related condition of multisystem atrophy, glottic narrowing during sleep has been suggested as a possible cause of sudden nocturnal death. This is not always detectable by fibreoptic examinations conducted while the patient was awake, and polysomnography may therefore be indicated in symptomatic patients. However, in another study of patients with progressive supranuclear palsy, frequent desaturations were not found.