News from the 131st Annual Meeting of the American Neurological Association, Chicago, October 8-11, 2006

December 1, 2006

To evaluate the degree to which newer antipsychotic agents are implicated in parkinsonism and whether drug-induced parkinsonism (DIP) is being adequately recognized, Christine D. Esper, MD, clinical instructor in neurology, and Stewart A. Factor, DO, professor of neurology at Emory University in Atlanta, performed a retrospective review of 354 consecutive patients in whom parkinsonian symptoms were newly diagnosed at a movement disorders clinic in 2004-2005

Parkinsonian Effects of Atypical Antipsychotic Drugs Underrecognized. To evaluate the degree to which newer antipsychotic agents are implicated in parkinsonism and whether drug-induced parkinsonism (DIP) is being adequately recognized, Christine D. Esper, MD, clinical instructor in neurology, and Stewart A. Factor, DO, professor of neurology at Emory University in Atlanta, performed a retrospective review of 354 consecutive patients in whom parkinsonian symptoms were newly diagnosed at a movement disorders clinic in 2004-2005.

The team identified 24 cases of DIP. Average patient age at onset of parkinsonism was 69 years, and the large majority of patients (68%) were women. Patients were symptomatic for an average 1.75 years before presenting for treatment, according to Esper. Fifty-two percent had tardive dyskinesia and 84% had tremor. Of note, the DIP diagnosis was missed in 83% of the patients who had previously been examined by a neurologist.

Atypical antipsychotic drugs were inculpated in 60% of cases of DIP. Metoclopramide and typical agents were inculpated in the remainder. The research team concluded that DIP is a common and underrecognized cause of parkinsonism.

Fortunately, parkinsonian symptoms either improved or resolved after discontinuation of antipsychotic therapy. Of the 18 patients who were followed up, 17 improved within an average 7 months, said Esper, who provided AppliedNeurology with updated data in relation to the study abstract published in the supplement to the October 2006 issue of Annals of Neurology.

Dextromethorphan/Quinidine Has Stronger Effect on Paroxysmal Crying Than Laughing. Although combination dextromethorphan/quinidine (DM/Q) has been shown to be useful in relieving the symptoms of pseudobulbar affect, a multicenter team specializing in amyotrophic lateral sclerosis (ALS) from the University of Wisconsin, the University of Miami Miller School of Medicine, and the University of San Francisco in partnership with researchers from the Center for Neurologic Study (CNS) and Avanir Pharmaceuticals, the manufacturer of the study drug, concluded that DM/Q has a stronger effect on controlling paroxysmal crying than laughing. The study reexamined data from research published in Neurology in 2004 (Brooks BR, Thisted RA, Appel SH, et al; AVP-923 ALS Study Group. Treatment of pseudobulbar affect in ALS with dextromethorphan/quinidine: a randomized trial. Neurology. 2004;63:1364-1370.) that included 140 patients with ALS and pseudobulbar affect.

The researchers found that although improvement in threshold and control in relation to paroxysmal crying and laughing were achieved by day 15 of therapy in patients taking a capsule containing 30 mg of dextromethorphan and 30 mg of quinidine twice daily for a total of 28 days, only improvement in control and threshold parameters related to paroxysmal crying were sustained at day 29. The threshold parameters for paroxysmal laughing were seen to weaken. In tandem with this finding, the researchers identified a "persistent decrease" in control of intrusive amusing thoughts among patients between day 15 and day 29 of the study.

Findings from another study on the value of DM/Q in the treatment of pseudobulbar affect suggest that DM/Q may ameliorate feelings of anger and frustration as well as typical symptoms of inappropriate crying or laughing. The study was a small, double-blind, placebo-controlled crossover trial that included 12 patients who received either DM/Q or placebo for 4 weeks and then were switched to the alternate regimen for another 4 weeks. Patients completed a 65-item emotional lability questionnaire that included items related to the Center for Neurologic Study-Lability Scale (CNS-LS) at baseline and posttreatment.

The researchers, who hailed from CNS in La Jolla, California, and Avanir Pharmaceuticals in San Diego, reported that DM/Q therapy was associated with a 16% reduction in episodes of anger, a 30% reduction in episodes of frustration, and a 29% reduction in CNS-LS scores.