Lim, 2012 Is 6 months of neuroleptic withdrawal sufficient to distinguish drug-induced parkinsonism from Parkinson's disease?

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Int J Neurosci. 2012 Oct 19. [Epub ahead of print]

Is 6 months of neuroleptic withdrawal sufficient to distinguish drug-induced parkinsonism from Parkinson's disease?

Lim T, Ahmed A, Itin I, Gostkowski M, Rudolph J, Cooper S, Fernandez H.

 

Source

 

1Center for Neurological Restoration, Cleveland Clinic Foundation , Ohio , USA.

 

Abstract at http://www.ncbi.nlm.nih.gov/pubmed/23078283

 

Abstract:

 

Background: Drug-induced parkinsonism (DIP) is the second commonest cause of akinetic-rigid syndrome in the western world. Differentiating DIP from Parkinson disease (PD) may be a challenge to clinicians. One of the factors distinguishing DIP from PD is that discontinuation of the neuroleptic agent in DIP should relieve the symptoms of parkinsonism. The majority of the literature uses the 6-month timeframe between the neuroleptic withdrawal and resolution of the symptoms of parkinsonism.

 

Methods: We report two cases of DIP wherein the symptoms of parkinsonism persisted more than 6-months from withdrawal of the dopamine receptor blocking agent (DRBA) and the results of their ioflupane iodine-123 (DaT) single photon emission computed tomography (SPECT) scan. DaT scan is a newly approved radiopharmaceutical in the US indicated for striatal dopamine transporter visualization to assist in the evaluation of adult patients with suspected parkinsonian syndromes. Results: The first case is a patient who developed parkinsonism from risperidone, while the second case developed parkinsonism from metoclopramide. In both cases, parkinsonism persisted 6 months after discontinuation of the DRBA, therefore DaT scan was obtained, showing normal striatal dopamine transporter uptake. Nine months after discontinuation of the DRBA, parkinsonism was significantly improved in both patients but not completely resolved.

 

Conclusion: Our 2 cases illustrate the possibility of persistent parkinsonism beyond 6 to 9 months from the time of neuroleptic withdrawal without evidence of pre-synaptic dopaminergic neuronal loss that would be suggestive of conversion to PD. We recommend that the official recommendation of the minimum time of neuroleptic withdrawal be modified to at least 1 year before entertaining the diagnosis of PD conversion in patients with exposure to DRBAs.