Essential Tremor Workup

Updated: Oct 22, 2018
  • Author: Deborah A Burke, MD; Chief Editor: Selim R Benbadis, MD  more...
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Workup

Approach Considerations

No biologic markers exist for essential tremor. If the family history and examination findings are indicative of essential tremor, no laboratory or imaging studies are required. However, if the family history and examination findings are not indicative of essential tremor, laboratory and imaging studies should be considered. [41, 42]

Laboratory investigations include the following:

  • Standard electrolyte panel

  • Thyroid function tests

  • Blood urea nitrogen (BUN)

  • Creatinine

  • Liver function tests

  • Serum ceruloplasmin (for Wilson disease)

Procedures

Electromyography or accelerometry can be used to assess tremor frequency, rhythmicity, and amplitude but is not part of the routine evaluation.

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Imaging Studies

Findings on computed tomography (CT) scanning and magnetic resonance imaging (MRI) of the head are normal in essential tremor. MRI helps to exclude structural and inflammatory lesions (including multiple sclerosis) and Wilson disease. MRI should be performed if the tremor has acute onset or stepwise progression.

Although the classic resting tremor of Parkinson disease is different in many aspects from that of essential tremor, it is often difficult to distinguish variants. Single-photon emission CT (SPECT) scanning using ioflupain 123 I (DaTSCAN) is now a US Food and Drug Administration (FDA)–approved procedure that can support a diagnosis of parkinsonism, hence decreasing the misdiagnosis of essential tremor as Parkinson disease. [1, 2, 3]

Midbrain ultrasonography has been suggested as a tool to differentiate essential tremor from Parkinson disease as a result of a study finding that high substantia nigra hyperechogenicity has a high positive predictive value for Parkinson disease. However, another study found a significant increase in substantia nigra hyperechogenicity in patients with essential tremor compared with controls. [43, 44, 45, 46]

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Other Tests

In 2017, researchers presented a new neuropsychological measure that can discriminate Parkinson's disease tremor and essential tremor with high diagnostic accuracy. The tremor stability index, derived from kinematic measurements of tremulous activity, was tested in a cohort comprising 16 rest tremor recordings in tremor-dominant Parkinson's disease and 20 postural tremor recordings in essential tremor, and validated on a second, independent cohort comprising a further 55 tremulous Parkinson's disease and essential tremor recordings. The index's maximum sensitivity, specificity and accuracy were 95%, 95% and 92%, respectively. [47]

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