Calcium channel blocker-induced parkinsonism: clinical features and comparisons with Parkinson's disease

Parkinsonism is a frequent side effect of some calcium channel blockers (CCB). CCB-induced parkinsonism (CCBIP) usually improves spontaneously after discontinuation of the offending drug, but many patients exhibit persistent symptoms. It is not known whether CCBIP represents subclinical idiopathic Parkinson's disease (IPD) unmasked by drugs. We prospectively studied (mean follow-up 18.9+/-13months) the spontaneous evolution of 36 patients with CCBIP, and compared the clinical and epidemiological characteristics with those of 38 patients with IPD. Most patients with CCBIP improved spontaneously. Twenty-four months after CCB withdrawal, only 14% exhibited akinetic rigid syndrome, but 92% of patients still had tremor. The CCBIP group differed from the IPD group in: age at onset (70.8+/-8.2 versus 59.1+/-10years, p<0.001), gender (30/36 female versus 20/38 male, p<0.01), presenting symptom (tremor at first evaluation: 34/36 in CCBIP versus 28/38 in IPD, p<0.03) and history of arterial hypertension (21/36 versus 7/38, p<0.001). Asymmetrical onset of symptoms was frequent in IPD, but not in the CCBIP group (24/38 versus 13/36, p<0.05).