Introduction: The differential diagnosis of a parkinsonian syndrome is extensive and complex. In most cases, however, a detailed clinical examination will help to differentiate between idiopathic Parkinson's disease (IPD) and other causes of parkinsonism.
Patients and methods: 10 patients with an average age of 65.1 years (range 60-70), of whom 6 were men and 4 women were referred to our department with a diagnosis of IPD and history of backwards falls. The average duration of disease was 4.7 years (range 4-7). All 10 patients had at presentation a severe akinetic-rigid syndrome with no other symptoms of IPD. I.v. apomorphine (APO) was administered to each of them at a rate of 8.9 mg/hr (range 15.3 mg/hr) for an average time of 5.4 hours (range: 3-10 hours).
Results: The improvement of the akinetic-rigid state in six of the patients during the i.v. infusion with APO helped to elicit signs that are atypical of IPD (ataxia and postural instability). Three of the patients did not respond to i.v. APO and one of them could not be evaluated, as he did not tolerate the infusion. Oral Dopa challenge or s/c APO bolus has not been as successful in helping to differentiate IPD from other parkinsonian syndromes.
Conclusions: The prompt detection of postural instability or retropopulsion is necessary in order to diagnose atypical parkinsonian syndromes. In difficult cases, continuous i.v. APO will improve the akinetic-rigid state and facilitate the detection of atypical signs. The pharmacokinetic characteristics of APO, and the advantage of it being possible to administer the drug i.v. in a few hours increases the viability of this test.