neurologic disorders
Parkinson Disease
Diagnosis of Parkinson Disease
Mainly clinical evaluation, based on motor symptoms Diagnosis of Parkinson disease is clinical. Parkinson disease is suspected in patients with characteristic unilateral resting tremor, decreased movement, or rigidity. During finger-to-nose coordination testing, the tremor disappears (or attenuates) in the limb being tested. During the neurologic examination, patients cannot perform rapidly alternating or rapid successive movements well. Sensation and strength are usually normal. Reflexes are normal but may be difficult to elicit because of marked tremor or rigidity. Slowed and decreased movement due to Parkinson disease must be differentiated from decreased movement and spasticity due to lesions of the corticospinal tracts. Unlike Parkinson disease, corticospinal tract lesions cause Paresis (weakness or paralysis), preferentially in distal antigravity muscles Hyperreflexia Extensor plantar responses (Babinski sign) Spasticity that increases muscle tone in proportion to the rate and degree of stretch placed on a muscle until resistance suddenly melts away (clasp-knife phenomenon) The diagnosis of Parkinson disease is supported by the presence of other signs such as infrequent blinking, lack of facial expression, and gait abnormalities. Postural instability is also present, but if it occurs early in the disease, clinicians should consider other possible diagnoses. In older patients, other possible causes of decreased spontaneous movements or a short-stepped gait, such as severe depression, hypothyroidism, or use of antipsychotics or certain antiemetics, must be excluded before Parkinson disease is diagnosed. To help distinguish Parkinson disease from secondary or atypical parkinsonism, clinicians often test responsiveness tolevodopa. A large, sustained response strongly supports Parkinson disease. A modest or no response tolevodopaat doses of at least 1200 mg/day suggests another form of parkinsonism. Causes of secondary or atypical parkinsonism can be identified by A thorough history, including occupational, drug, and family history Evaluation for neurologic deficits characteristic of disorders other than Parkinson disease Neuroimaging when patients have atypical features (eg, early falls, early cognitive impairment, ideomotor apraxia [inability to imitate hand gestures], hyperreflexia) 