Emergence of Parkinson's disease in essential tremor: a study of the clinical correlates in 53 patients

Mov Disord. 2008 Aug 15;23(11):1602-5. doi: 10.1002/mds.22161.


Patients with essential tremor (ET) may develop Parkinson's disease (PD); however, few studies have examined the clinical features of this combination syndrome. Fifty-three patients with ET-PD were studied and compared to 53 PD and 150 ET patients. Although the latency from onset of ET to PD was brief (<5 years) in 38.5%, in a sizable proportion (30.8%), it was very long (>20 years). The gender distribution of ET-PD (67.9% male) was identical to that of PD (67.9% male), yet differed from that of ET (50.0% male) (P = 0.02). The initial cardinal sign of PD was rest tremor in 100% of patients. In ET-PD, the side of greatest initial ET severity usually matched that of greatest PD severity (P < 0.05). In ET-PD, male gender predominated and the sidedness of the ET and PD usually matched. The co-occurrence of the two diagnoses in the same patient may be mechanistically related.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age of Onset
  • Aged
  • Aged, 80 and over
  • Databases, Factual / statistics & numerical data
  • Disease Progression
  • Essential Tremor / complications*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Parkinson Disease / etiology*
  • Severity of Illness Index
  • Sex Factors