3A. Differential diagnosis of tremors

Classification

Tremors are classified as either resting tremors or action tremors. Resting tremors occur during rest, while action tremors occur during voluntary movement. There are three subtypes of action tremor.

  • Resting tremor – occurs in rest
  • Action tremor – occurs during voluntary contraction
    • Postural tremor – when holding arms out against gravity
    • Kinetic tremor – occurs when moving the arms
      • Essential tremor
      • Intention tremor
      • Task-specific tremor

Resting tremor

Resting tremor occurs in parkinsonism, whether it’s primary due to Parkinson disease or secondary parkinsonism.

As the name suggests, this occurs during rest. It’s asymmetric and is sometimes called a pill-rolling tremor because they perform a special movement of the thumb and index finger as if you were rolling a pill between them.

Physiological tremor

Physiological tremor is a kind of postural tremor which occurs in healthy people who are exposed to certain factors, like:

  • Stress
  • Sympathetic activation
  • Hyperthyroidism
  • Caffeine
  • Alcohol withdrawal

It’s a fine tremor with low amplitude. No treatment is necessary, only avoiding the trigger. Benzodiazepines may be used in severe cases.

Essential tremor

Essential tremor is a kind of postural or kinetic tremor. It’s a hereditary autosomal dominant condition which worsens with stress, fatigue, or caffeine. It’s a fine tremor which affects the hands and the head. Interestingly, it improves with alcohol.

Pharmacological treatment like propranolol and antiepileptics can be used, but unfortunately they usually don’t improve the symptoms a lot. In very severe cases we can use deep brain stimulation of thalamic nuclei. DBS can be effective for any kind of disabling tremor.

Intention tremor

Intention tremor is a kind of kinetic tremor caused by cerebellar injury, whether due to cerebellar stroke, trauma, multiple sclerosis, alcohol abuse, etc. It occurs during target-directed voluntary movements and is a coarse (low frequency) tremor where the person makes a slow “zigzag” movement towards the target.

Other types of tremor

Neuropathic tremor can occur in case of any neuropathy, like diabetic neuropathy. The clinical features are variable.

Psychogenic tremor is caused by psychiatric disease and it’s characteristic for it that the clinical features change when the patient is distracted.

Flapping tremor, also called asterixis, is due to hepatic or uraemic encephalopathy and involves a characteristic flapping motion of the hands.


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