Tremor

INDEX

ORIGIN

Holmes’ tremor is usually caused by lesions in both the dopaminergic nigrostriatal as well as the cerebello-thalamic pathways.  It is often accompanied by other neurological signs. A delay of 4 weeks to even 2 years has been described between the initial lesion (e.g., a cerebrovascular accident) and the development of Holmes’ tremor. 

CLASSIFICATION

Holmes’ Tremor has been labelled under different names in the past (e.g. rubral tremor, midbrain tremor, myorhythmia, mixed extrapyramidal tremor or Benedikt’s syndrome). Thalamic tremor is typically viewed as a separate entity, but there is potential overlap between thalamic tremor and Holmes' tremor.

CLINICAL FEATURES

Clinically, it is the combination of:

  1. A parkinsonian-like rest tremor AND
  2. A cerebellar tremor.

Since the tremor is caused by lesions of the cerebellothalamic and nigrostriatal pathways it follows that it consists of a combination of rest, postural, and kinetic components. There is a low frequency tremor at rest (<4.5 Hz), which increases upon posture, and even more so with intention. The tremor at rest is high amplitude and irregular, and commonly involves both proximal and distal muscles at frequencies of 2–5 Hz. Holmes’ tremor is not as rhythmic as most other tremors. 

There is frequently additional evidence of damage to other systems (long tract signs, eye movement disturbance).

AGE OF ONSET

Variable

DISTRIBUTION

Typically involves one arm, slightly less commonly, one side.

Occasionally, if bilateral lesions, tremor is seen bilaterally.

DIAGNOSIS

Based on clinical grounds, usually with clear history and imaging indicating that Holmes tremor is an appropriate clinical possibility.

DIFFERENTIAL DIAGNOSIS

Thalamic involvement is often accompanied by dystonia and impaired proprioception.See section: Thalamic Tremor.

Myorhythmia may need to be considered.

DIAGNOSTIC TESTS

Imaging; of note, imaging of the nigrostriatal pathways may be normal.  As would be anticipated, evidence of nigrostriatal damage may predict the degree of response to levodopa.

TREATMENT

Very limited. Levodopa may be of some benefit in a few cases; average dose reported in one series was 700 mg daily (range 300-1000mg)1.

Ventral intermediate nucleus (VIM) thalamotomy, is reported to show improvement in tremor in some patients1. However, currently, the benefit of DBS for Holmes' tremor is uncertain, and it is likely appropriate to adopt a cautious approach with respect to potential benefit from surgery.

REFERENCES

1            Raina GB, Cersosimo MG, Folgar SS, et al. Holmes tremor: Clinical description, lesion localization, and treatment in a series of 29 cases. Neurology 2016; 86: 931–8.