Review Question - QID 217649

This patient with a low-amplitude, high-frequency, bilateral, and symmetric postural tremor exacerbated by caffeine use and stress is most likely experiencing physiologic tremor.

Broadly, tremors can be classified into resting or action tremors based on when they present. Resting tremors occur when the involved part of the body is relaxed and supported against gravity. They are exacerbated by mental stress or movement of another part of the body and improved with voluntary movement of the affected limb. Action tremors, which comprise the majority of tremors, occur with muscle contraction. While tremors may be associated with medical conditions (e.g. medications, neurocognitive disorders), physiologic tremors are action tremors that are the most commonly-encountered in patient care. Physiologic tremors present as a bilateral, action tremor mostly in the wrists and hands, and worsen with caffeine intake. Treatment involves mitigating the precipitant causes, which may include decreasing caffeine intake and managing stress levels.

Alty et al. discuss the classification, differential diagnosis, and distinguishing features of various tremors.

Incorrect Answers:
Answer 1: Cerebellar tremor is a low-frequency, resting tremor caused by cerebellar injury from multiple sclerosis, stroke, or brainstem tumors. These patients will have other signs of cerebellar injury such as dysmetria, dyssynergia (abnormal heel-to-shin test), and ataxia.

Answer 2: Drug-induced tremors should be considered in patients started on a new medication. The most common causative medications are stimulants of the sympathetic nervous system such as amphetamines, terbutaline, and pseudoephedrine and psychoactive medication such as tricyclic antidepressants, haloperidol, valproic acid, and fluoxetine. This patient is not taking any medications regularly.

Answer 3: Parkinson disease is commonly associated with resting tremors that are absent during voluntary activity. The tremor is described as asymmetric, low-frequency, pill-rolling, and progressing from hand to forearm. Other associated symptoms include bradykinesia, rigidity, and postural instability, which are not exhibited in this patient.

Answer 5: Psychogenic tremor is characterized by abrupt onset, spontaneous remission, changing tremor characteristics, and extinction with distraction. It is associated with major stressful events in an individual's life and is a diagnosis of exclusion. Unlike physiologic tremors, psychogenic tremors demonstrate variability in both amplitude and frequency and are typically not exacerbated by caffeine intake.

Bullet Summary:
Physiologic tremor, presenting as a bilateral, action tremor mostly in the wrists and hands, is visible under states of stress or increased sympathetic output and may worsen with caffeine intake.