Ep 178 – Tremor

A tremor is defined as an involuntary rhythmic oscillation of one or more body parts, mediated by alternating contractions of reciprocally acting muscles. Tremors typically affect the upper extremities but can also affect the head, chin, voice or legs. Although some tremors may be mild and cause little impact to quality of life, requiring no treatment, others may impair activities of daily living or occupation, which may lead to embarrassment and social withdrawal. In this episode, Dr Roger Henderson gives an overview of the different types of tremor, looking at ways of distinguishing them and how each is usually managed.

Key take-home points

• Tremor is not a diagnosis, but a symptom: the outward manifestation of dysfunction in certain motor circuits within the brain.
• The pathophysiology of tremors is very varied.
• A rest tremor shows up when the affected limb is fully supported and not being voluntarily moved. Postural tremors happen when the patient is holding a position against gravity, such as when their arms are outstretched.
• Physiological tremors tend to be high frequency and low amplitude. Parkinsonian tremors usually run at about 4 to 6 Hz, while essential tremors are slightly faster at around 6 to 10 Hz.
• Essential tremors are the most common tremor seen in primary care.
• These are thought to affect around 0.5% of the population, with men and women equally affected.
• The onset of a familial essential tremor is typically during childhood, whereas a sporadic essential tremor usually occurs after the age of 40.
• A Parkinsonian tremor usually begins unilaterally and is classically described as a “pill-rolling” motion of the fingers at rest.
• Cerebellar tremor typically presents as an intention tremor, meaning it worsens as the hand approaches a target. This is because of damage to the cerebellum or its pathways, often due to multiple sclerosis, stroke, trauma or tumours.
• With a dystonic tremor, patients have tremor in a body part that also shows signs of dystonia: abnormal, often twisted postures due to sustained muscle contractions. The tremor tends to be irregular and may vary depending on posture or action.
• Drug-induced tremors are common, especially with medications like valproate, lithium, selective serotonin reuptake inhibitors or antipsychotics. These tremors are usually symmetric and postural, which may improve when the offending agent is reduced or stopped.
• Functional psychogenic tremors often begin suddenly and vary in frequency, which is inconsistent during examination.
• When approaching a patient with tremor, clinical evaluation is the most important step. A good history and neurological exam can often get you most of the way to a diagnosis.
• Investigations may be warranted, but not in every case or if there is a characteristic presentation of an essential or physiological tremor.
• Treatment must be individualised to each patient; while pharmacological options still remain the first step, surgical therapies have transformed the outlook for many patients with a refractory tremor.

Key references

1. Bhatia KP, et al. Mov Disord. 2018;33(1):75-87. doi: 10.1002/mds.27121.
2. Clark LN, Louis ED. Handb Clin Neurol. 2018:147:229-239. doi: 10.1016/B978-0-444-63233-3.00015-4.
3. Crawford P, Zimmerman EE. Am Fam Physician. 2011;83(6):697-702.
4. Schneider SA, Deuschi G. Neurol Clin. 2015;33(1):57-75. doi: 10.1016/j.ncl.2014.09.005.
5. Lenka A, Jankovic J. Front Neurol. 2021;12:684835. doi: 10.3389/fneur.2021.684835.