Tremor

INDEX

ORIGIN

Injury to the deep cerebellar nuclei and cerebellar outflow tracts are likely involved in tremor production.  Cerebellar tremor does not emerge from oscillating loops but rather altered characteristics of feedforward or feedback loops.

CLASSIFICATION

Intention tremor: The intention component of kinetic tremor is considered to be characteristic of cerebellar pathology, although it is probable that lesions of the superior cerebellar peduncle, rather than the cerebellum itself, are responsible for this.

Intention tremor syndromes consist of intention tremor at <5 Hz, with or without other localizing signs, and are usually caused by a lesion in the cerebellothalamic pathway.

Postural tremor: Various types of postural tremor have been described including slow oscillations of the arms about the shoulders, or legs about the hips. This type of tremor is referred to as titubation when it affects the head and trunk, and it can be particularly striking when a patient is standing. It is often accompanied by other signs of cerebellar disease and is most commonly seen in patients with multiple sclerosis, although mass lesions, vascular disease, and hereditary or acquired cerebellar degenerations may all result in this form of movement.

The association between tremor and ataxia, at least in the spinocerebellar ataxias, is not linear, suggesting that different circuits underlie these phenomena1.

CLINICAL FEATURES

Classical cerebellar tremor is a slow (<5 Hz) intention tremor ipsilateral to the underlying cerebellar abnormality. Postural tremor and simple kinetic tremor may also be present but a rest tremor does not occur (if present is an indication that the patient is unable to completely relax). Titubation is another tremor manifestation of cerebellar disease and is a low frequency oscillation (around 3 Hz) of the head and trunk.

Cerebellar postural and action tremors are irregular and often of high amplitude, causing severe functional disability. With no rest component, patients may appear normal until they initiate movement or assume a steady posture, and tremor is most pronounced with intention. Irregular postural tremor of the head and rhythmic postural sway (truncal tremor) may also occur. 

AGE OF ONSET

Variable.

DISTRIBUTION

As with all tremors, the frequency of cerebellar tremor depends upon the part of the body that is affected.  Tremor frequencies range from 3–8 Hz in the arms, 1–3 Hz in the legs, and 2–4 Hz in the trunk.

DIAGNOSIS

Based on history, examination, imaging and appropriate tests for cerebellar disease.

DIFFERENTIAL DIAGNOSIS

Holmes' tremor; neuropathic tremor, Wilson's disease, deafferentation/"pseudoathetosis". Review of head tremor in dystonia and ET

DIAGNOSTIC TESTS

Imaging, genetic work up for SCA and other forms of inherited cerebellar disease.

TREATMENT

Limited and unclear role for DBS.

REFERENCES

  1. Lai RY, Tomishon D, Figueroa KP, et al. Tremor in the Degenerative Cerebellum: Towards the Understanding of Brain Circuitry for Tremor. Cerebellum. 2019;18(3):519-526.