PARKINSON DISEASE   61A

A 63-year-old man comes to the clinic with a several month history of difficulty with his gait and coordination. He finds walking difficult and has almost fallen on a number of occasions, especially when trying to change directions. He has also found that using his hands is difficult, and other people have noticed that his hands shake. Physical examination is notable for a resting tremor in the hands that disappears with intentional movement. He has a shuffling gait with difficulty turning. There is “cogwheeling” rigidity in his arms, a jerky sensation with passive flexion and extension of the arms.

What are the salient features of this patient’s problems? How do you think through his problems?

Salient features: Gait disturbance; difficulty in changing directions; resting tremor without intention tremor; shuffling gait; cogwheeling rigidity of limbs on physical examination

How to think through: This patient has several characteristic physical findings of parkinsonism. What other findings are commonly seen in Parkinson disease and should be explored here? (Name as many as possible, then see Symptoms and Signs.) Before concluding that this patient has idiopathic Parkinson disease, what other processes should be considered? (Extrapyramidal side effects of neuroleptic medications; multisystem atrophy, characterized in part by dysautonomia; normal-pressure hydrocephalus, characterized by difficulty initiating gait and incontinence; progressive supranuclear palsy.) What neurodegenerative process is associated with Parkinson disease? (Dementia with Lewy bodies, characterized by paranoia, visual hallucinations, waxing and waning mental status, sometimes resembling delirium.) After a diagnosis of idiopathic Parkinson disease is made, how should the patient be treated? What pharmacologic classes are used? (Anticholinergics, amantadine, carbidopa–levodopa and other dopaminergic agonists; see Treatment.) Why might we delay treatment with levodopa and use other agents initially? (Although levodopa is the most effective treatment for Parkinson disease, it can cause both dyskinesias as well as the “on–off” phenomenon in which bradykinesia alternates unpredictably with dyskinesias.) What nonpharmacologic interventions are available? (Deep brain stimulation. Additionally, all patients should have physical therapy, home safety evaluation, and mobility aids as needed.)

PARKINSON DISEASE   61B

What are the essentials of diagnosis and general considerations regarding Parkinson disease?

Essentials of Diagnosis

Any combination of tremor, rigidity, bradykinesia, and progressive postural instability

Cognitive impairment is sometimes prominent

General Considerations

Parkinson disease is a common disorder; idiopathic Parkinson disease often begins between ages 45 and 65 years.

Dopamine depletion caused by degeneration of the dopaminergic nigrostriatal system leads to an imbalance of dopamine and acetylcholine.

Exposure to toxins and certain medications can lead to parkinsonism, including manganese dust, carbon disulfide, severe carbon monoxide poisoning, 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) (a recreational drug), neuroleptic drugs, reserpine, and metoclopramide.

Postencephalitic parkinsonism is becoming increasingly rare.

Only rarely is hemiparkinsonism the presenting feature of a space-occupying lesion.

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