The spiral axis as a clinical tool to distinguish essential tremor from dystonia cases

Monika Michalec, Nora Hernandez, Lorraine N. Clark, Elan D. Louis

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Background: Tremor is a common feature of a variety of neurological disorders. In genetic studies of essential tremor (ET), investigators need to screen potential enrollees by mail or telephone to exclude those with other neurological conditions, especially dystonia. In clinical settings, the differentiation of ET and dystonia may also be very challenging. We hypothesized that the spiral axis, described below, is a useful screening tool to distinguish ET cases from dystonia cases. Methods: We analyzed the hand-drawn spirals of 135 individuals enrolled in a genetics study at Columbia University Medical Center. Each of the four spirals was assessed for the presence of a single identifiable tremor orientation axis, and a spiral axis score (range=0-4) [a single axis on all 4 spirals] was assigned to each enrollee. Results: There were 120ET cases and 15 cases with dystonic tremor. Most (101/120, 84.2%) ET cases had an axis score ≥1 vs. only half (8/15, 53.3%) of the dystonia cases (p=0.02). Receiver Operator Curve (ROC) analysis revealed that the use of a spiral axis score ≥2 as a cut off would exclude 60.0% of dystonia cases while including 67.5% of ET cases. Conclusion: Handwritten spirals appear to have a single predominant axis in more ET than dystonia cases. The evaluation of this axis has moderate diagnostic validity as a screening tool to distinguish ET cases from those with dystonia. Although this study did not assess the utility of this tool in clinical practice settings, future studies should do so.

Original languageEnglish (US)
Pages (from-to)541-544
Number of pages4
JournalParkinsonism and Related Disorders
Issue number5
StatePublished - May 2014
Externally publishedYes


  • Axis
  • Dystonia
  • Essential tremor
  • Spiral

ASJC Scopus subject areas

  • Neurology
  • Geriatrics and Gerontology
  • Clinical Neurology


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