This is a rare presentation of a thalamic tumour solely with tremor. A case series of 225 patients with astrocytomas of the basal ganglia or thalamus described tremor in 12 patients, six of whom suffered a Holmes’ tremor.2
Although initial presentation is not published, all these patients had other symptoms or signs at the time of biopsy. Thalamomesencephalic cavernomas and ependymal cysts have been reported presenting as parkinsonian or Holmes’ tremor,3
and a case series of bilateral thalamic tumours in children reports one case presenting with unilateral intention and rest tremor.4
Other tumours that present with tremor include those presenting with unilateral resting tremor and subsequently parkinsonism which are usually extra-axial, although intra-axial tumours usually distant from the basal ganglia have also been reported.5
Posterior fossa masses can present with intention tremor although other cerebellar signs and symptoms are usually present. It is therefore important to consider intracranial tumours in a patient presenting with unexplained tremor. In this case the diagnosis was masked by a thalamic infarct, but the diagnosis of an underlying tumour might have been considered on the basis of progressive symptomatology.
The Holmes’ tremor, also known as rubral or midbrain tremor, was first described by Gordon Holmes in 1904.1
It is characterised by a 2–5 Hz, upper extremity tremor present at rest and exacerbated by posture or movement. Most commonly this tremor is associated with pathology of the upper brainstem including tumours, vascular insults and multiple sclerosis.6,7
Pathology in the thalamus is a less common cause although tumours, cysts, vascular insults and abscesses leading to Holmes’ tremor have been described.4,8,9
The tremor is believed to result from disruption of the dentate–rubro–olivary and cerebello–thalamo–cortical pathways. Concurrent lesion of nigrostriatal pathways is postulated to cause the resting component which may respond to levodopa and dopamine agonist pharmacotherapy.10
Tumours of the thalamus may be treated by surgical resection, fractionated radiotherapy, stereotactic radiosurgery for smaller low grade tumours, and more recently endoscopic management.11
Gross total resection can be successful with long term survival and acceptable morbidity, particularly in children. Functional stereotactic surgery has also been used in the past and more recently deep brain stimulation has shown efficacy in a case of Holmes’ tremor caused by a thalamic abscess.9
Pharmacological treatment of Holmes’ tremor with levodopa or dopamine agonists may be beneficial, but results are disappointing in non-vascular aetiologies.7
We felt that, given the longstanding nature of the lesion and the minimal impact on the patient’s quality of life, watchful waiting was the appropriate management plan in this case.
- A rare but important cause of isolated Holmes’ tremor is thalamic tumour.
- This is most likely due to disruption of cerebello–thalamo–cortical pathways.
- Management may be watchful waiting, open or endoscopic surgical resection, radiotherapy or radiosurgery, depending on aetiology and degree of symptoms.