Cabergoline and Silent Aspiration in Elderly Patients with Stroke

To the Editor: Swallowing disorders play an important role in the pathogenesis of aspiration pneumonia, and silent aspiration is one of the main causes of pneumonia in elderly people with stroke. It has been reported that silent aspiration commonly occurs subsequent to impairment of the cough reflex and swallowing reflex.¹

Levodopa used as the criterion-standard therapy for Parkinson's disease has been shown to improve the swallowing reflex in elderly patients with stroke,² but long-term levodopa therapy generates motor complications consisting of involuntary choreoathetoid and dystonic movements and response fluctuations.³ In contrast, the modern dopamine agonists, cabergoline, pergolide, pramipexole, and ropinirole, produce less dyskinesia^4,5 and lead to reduced loss of dopaminergic neurons than levodopa in patients with Parkinson's disease.⁶ Therefore, we investigated whether cabergoline improves silent aspiration and compared the effects of cabergoline with those of amantadine⁷ and angiotensin-converting enzyme (ACE) inhibitors,⁸ which have been reported to be effective in treatment of silent aspiration in elderly patients with stroke.

The eligible patients had a history of stroke, but were not bedridden. Fifty-one patients (23 men and 28 women) with silent aspiration detected using the method described below were enrolled. Of 51 patients, 39 patients (18 men and 21 women) were normotensive; randomization was performed using a random-numbers table. The list was held independently of the investigators. The patients were randomly assigned cabergoline 0.25 mg per day (13 patients, mean age±standard deviation=80±2), amantadine 50 mg per day (14 patients, mean age 79±4), or no active treatment (control group; 12 patients, mean age 79±7). The remaining 12 patients (5 men and 7 women, mean age 79±4) were hypertensive and received imidapril hydrochloride 5 mg per day.

To determine the occurrence of silent aspiration, 1 mL technetium tin colloid was given to patients during sleep via a nasal catheter. At 9 a.m. on the next day, silent aspiration was checked for by imaging⁹ before and 12 weeks after oral administration of drugs or no active treatment.

Silent aspiration was observed in all patients before treatment but disappeared in 10 (76.9%) of 13 patients administered cabergoline, 10 (71.4%) of 14 patients administered amantadine, and nine (75.0%) of 12 patients administered imidapril hydrochloride. In contrast, silent aspiration disappeared in only one (8.3%) of 12 control patients. Improvement of silent aspiration did not differ between cabergoline, amantadine, and imidapril hydrochloride (P>.20), but significant differences in improvement of silent aspiration were observed between active and no active treatments (P<.01).

These findings suggest that cabergoline, a new dopamine agonist, improves silent aspiration as efficiently as amantadine⁷ and ACE inhibitors⁸ in elderly patients with stroke. Therefore, cabergoline treatment may be useful for preventing aspiration pneumonia in elderly stroke patients.