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American Academy of Neurology Practice Parameters: Parkinson Disease Diagnosis and Treatment
These parameters reveal many areas of missing evidence regarding PD diagnostic tools and treatments.
An expert panel assembled by the American Academy of Neurology (AAN) has produced four articles reviewing published data on clinical aspects of Parkinson disease (PD) using the AAN’s published guidelines for Practice Parameter development. They grade the level of the evidence as A, B, C, or U (unknown). Some of the authors have received funding from, consulted for, or spoken on behalf of manufacturers of treatments for PD.
Regarding distinguishing PD from other parkinsonian disorders, the authors rate as useful (level B) assessments that measure levodopa and apomorphine responsiveness, olfaction, early falls, symmetry of motor symptoms and signs, disease progression, tremor, and autonomic function. Positive findings on some of these assessments support a diagnosis of PD; others support a diagnosis of a different parkinsonian disorder. Assessments using SPECT, PET, MRI, brain sonography, and physiologic studies have only level C or level U evidence. Older age at diagnosis and early akinetic rigidity are considered indicators of poor prognosis (level B). Early tremor is deemed a sign of relatively good prognosis, whereas postural instability portends worse prognosis (both level C).
One report covers the somewhat overlapping topics of neuroprotection and alternative therapies and documents a lack of evidence supporting these interventions. Vitamin E has level B evidence for no benefit for either neuroprotection or symptom treatment. There is insufficient evidence (level U) of neuroprotection with dopamine agonists, coenzyme Q10, rasagiline, amantadine, and thalamotomy. Levodopa has level B support for not accelerating disease progression. Exercise and the various therapies (speech, occupational, physical) have only level C support for symptom treatment; alternative treatments, level U support.
To treat fluctuations ("off" time), entacapone and rasagiline have level A evidence supporting efficacy; pramipexole, ropinirole, pergolide, and tolcapone, level B support; and apomorphine, cabergoline, and selegiline, level C support. There is level C evidence of ineffectiveness of bromocriptine and sustained-release carbidopa/levodopa. For levodopa dyskinesias, amantadine is the only drug treatment supported by acceptable data (level C). Similarly, only ropinirole has acceptable supporting evidence, albeit level C, for reducing "off" time. Deep brain stimulation of the subthalamic nucleus has only level C support for reducing dyskinesias and "off" time. Other stimulation targets have level U support.
Only amitriptyline use has support for depression treatment (level C), despite decades of concern about depression in PD; clozapine (level B) and quetiapine for psychosis treatment (level C); and rivastigmine and donepezil for dementia treatment (both level B). Evidence against olanzapine for psychosis is level B.
Comment: These impressive guidelines illustrate how little high-quality evidence exists regarding diagnosis and treatment of Parkinson disease. The guidelines define the panel’s level of confidence in each recommendation. The guidelines may not represent the best medical practice, and they do not pretend to. They do, however, force us to reflect on and distinguish what we know from what we think we know. The panel’s recommendations reflect data, and not necessarily judgment. To paraphrase an old saw, evidence of quality and quality of evidence are not the same. The guidelines must be interpreted accordingly.
— Joseph H. Friedman, MD
Dr. Friedman is Director, NeuroHealth Parkinson’s Disease and Movement Disorders Center, Warwick, RI; and Clinical Professor, Department of Clinical Neurosciences, Brown Medical School, Providence, RI. He has received funds for lectures, consulting, or research over the past year from the following manufacturers of treatments for Parkinson disease: Astra Zeneca, Ovation, Acadia, Novartis, GlaxoSmithKline, Boehringer Ingelheim, Teva, and Janssen.
Published in Journal Watch Neurology August 1, 2006
Citation(s):
Suchowersky O et al. Practice parameter: Diagnosis and prognosis of new onset Parkinson disease (an evidence-based review): Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2006 Apr 11; 66:968-75.
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Suchowersky O et al. Practice parameter: Neuroprotective strategies and alternative therapies for Parkinson disease (an evidence-based review): Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2006 Apr 11; 66:976-82.
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- Medline abstract (Free)
Pahwa R et al. Practice parameter: Treatment of Parkinson disease with motor fluctuations and dyskinesia (an evidence-based review): Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2006 Apr 11; 66:983-95.
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- Medline abstract (Free)
Miyasaki JM et al. Practice parameter: Evaluation and treatment of depression, psychosis, and dementia in Parkinson disease (an evidence-based review): Report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2006 Apr 11; 66:996-1002.
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- Medline abstract (Free)