TREMOR

71 TREMOR

General Discussion

The first step in evaluating any patient with tremor is to characterize the tremor. All humans have physiologic tremor of the hands which may be enhanced under stressful circumstances. In addition to this normal form of tremor, there are several pathologic tremors that are generally categorized as resting tremor, action tremor, and intention tremor. Action tremor is the most prevalent of these types.

Resting tremor occurs while the limb is relaxed, stationary, and supported against gravity. The amplitude increases during mental stress such as counting backwards and with general movement such as walking. Resting tremor diminishes with target-directed movement such as the finger-to-nose test.

Action tremor occurs during sustained extension of the arm or during voluntary motion such as writing or pouring. The differential diagnosis of an action tremor includes essential tremor, enhanced physiologic tremor, Parkinson’s disease, adult-onset idiopathic dystonia, and Wilson’s disease. Essential tremor is a visible tremor that occurs when the affected body part maintains position against gravity. It is the most common movement disorder worldwide and has a bimodal age distribution in the teens and 50s. Parkinson’s disease is 20 times less common than essential tremor yet affects approximately one million Americans. Initial symptoms include resting tremor beginning in one arm, typically as a flexion–extension elbow movement, a pronation–supination of the forearm, or a pill-rolling finger movement. This tremor worsens with stress and diminishes with voluntary movement. Other signs of Parkinson’s disease include rigidity, bradykinesia, impaired postural reflexes, and masked facies.

Intention tremor is a coarse terminal tremor that occurs during visually guided movements as the limb approaches a target. There is significant amplitude fluctuation as the target is approached.

Drug-induced tremor should be differentiated from other forms of tremor. First, other medical causes of tremor such as hyperthyroidism and hypoglycemia should be ruled out. Factors that suggest drug-induced tremor include a temporal relation to the start of therapy with the drug, a dose-response relation, and a lack of tremor progression. Additionally, drug-induced tremor is symmetric for most drugs, except in the setting of drug-induced parkinsonism, in which patients commonly develop unilateral resting tremor. Older age places the patient at higher risk for drug-induced tremor.

Cerebellar tremor presents as unilateral or bilateral, low-frequency intention tremor caused by multiple sclerosis, stroke, or brainstem tumor. Finger-to-nose, finger-to-finger, and heel-to-shin testing results in worsening tremor as the extremity approaches its target. The patient may also have abnormalities of speech, gait, and ocular movements.

Psychogenic tremor is occasionally a consideration in the differential diagnosis of tremor. Psychogenic mimicking is usually diagnosed by distracting the patient with other motor or cognitive tasks. Psychogenic tremor decreases or stops with distraction while organic tremor stays the same or increases.

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Aug 17, 2016 | Posted by admin in PEDIATRICS | Comments Off

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