Essential Tremor

18-F fluorodopa (FDOPA) PET scans of a normal subject (left) and a patient with Parkinson's disease (right). The relative absence of tracer (red = high uptake, blue = low uptake) in the deep grey-matter nuclei (striatum) of the patient with Parkinson's disease reflects the loss of nerve cells in the substantia nigra. The clinical symptoms of Parkinson's disease become apparent when the loss of nigral neurons approaches 80%. Serial FDOPA PET scans have been used to monitor and quantity the progression of Parkinson's disease and to assess the efficacy of potential neuroprotective agents.

About

• A benign but troubling neurological illness inherited as an autosomal dominant
• Patients and the family of those with BET often worry that they have PD which is what usually initiates their referral to a neurologist or other doctor interested in movement disorders.

Clinical

• It can be difficult to differentiate a mild tremor from an early presentation of PD.
• However the lack of bradykinesia, normal gait, symmetry and the lack of progression over time are all suggestive of BET.
• Essential tremor (ET) has a gradual onset of 4 to 12 Hz postural upper limb tremor (less commonly head or voice), with no other neurologic signs except for cog wheeling
• Leg tremor may also occur.
• In rare cases the tremor can be severe and for a small cohort of patients, stereotactic neurosurgery has been used.
• Head nodding tremor also known as Titubation is also seen. The voice may also be affected

Other findings

• A family history of BET may also be present as it may well be inherited as an autosomal dominant.
• Life expectancy is normal though there was once a paper suggesting that those with ET have an increased life expectancy but I am not sure that this still is true

Investigations

• 18-F fluorodopa (FDOPA) PET can be done to help differentiate from PD though is only done in a minority of patients. One can assess the uptake of tracer in the deep grey-matter nuclei (striatum) of the patient with Parkinson's disease reflects the loss of nerve cells in the substantia nigra.
• Check TFT - cause of mild tremor
• In patients younger than 40 yr with other neurologic abnormalities, consider checking caeruloplasmin, serum Cu, 24-hr urine Cu to rule out Wilson's disease which has a classical wing beating tremor

Differential

• Anxiety states
• Parkinson's disease - head titubation uncommon with PD. Lack of improvement with alcohol in PD. BET has no bradykinesia or rigidity
• Wilson's disease especially in the young

Management

• Nowadays scans can be done to help where there is a need to differentiate PD and BET but are not generally accessible outside major centres and the diagnosis is really clinical and a case of expectant watching over time.
• No treatment needed in most.
• Reassured that it is not PD is often enough
• Small amounts of Alcohol help but rarely the basis of a good therapeutic strategy
• Beta-blockers
• Primidone (anticonvulsant)
• Mirtazepine (antidepressant)