 |
|
Clinical Subtypes of Essential Tremor
Elan D. Louis, MD, MS;
Blair Ford, MD;
Livia F. Barnes, MPH
Arch Neurol. 2000;57:1194-1198.
Background There is clinical variability in essential tremor (ET), but it is not clear whether this variability is because of the existence of distinct clinical subtypes of ET (ie, forms of ET that may differ in their etiology, rate of progression, or response to treatment).
Objectives To examine in a group of ET cases the age of onset, anatomic distribution, and rate of progression of tremor, and to look for associations between these factors.
Methods Cases of ET were ascertained from a community (n = 60) and a tertiary referral clinic (n = 55) in northern Manhattan, New York, NY. All subjects underwent an interview and videotaped tremor examination. Rate of progression was estimated based on the tremor severity and reported disease duration at the time of evaluation.
Results Age of onset was bimodally distributed in clinic cases. There were differences in the anatomic distribution of the tremor (arm tremor only vs head and arm tremor vs isolated head tremor). Rate of progression was distributed exponentially; there was a large cluster of subjects with slower rates of progression, and a smaller number who had faster rates. There was an association between age of onset and rate of progression (r = 0.46-0.50, P<.002); cases with older age of onset (>60 years) progressed more rapidly (P<.001). In addition, upper limb tremor progressed more slowly among those with concomitant head tremor (P = .03).
Conclusions Essential tremor is not a homogeneous condition. There are differences in age of onset, anatomic distribution of tremor, and rate of progression. The ET in several groups of patients in this study (those with age of onset >60 years and those without head tremor) progressed more rapidly, suggesting that these ET cases may define distinct clinical subtypes. These subtypes should be further assessed for etiologic and genetic heterogeneity as well as differences in responsiveness to therapeutic agents.
From the Gertrude H. Sergievsky Center (Dr Louis and Ms Barnes) and the Department of Neurology (Drs Louis and Ford), College of Physicians and Surgeons, Columbia University, New York, NY.
RELATED ARTICLE
Archives of Neurology Reader's Choice: Continuing Medical Education
Arch Neurol. 2000;57(8):1241-1242.
FULL TEXT
THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
Common Misdiagnosis of a Common Neurological Disorder: How Are We Misdiagnosing Essential Tremor?
Jain et al.
Arch Neurol 2006;63:1100-1104.
ABSTRACT
| FULL TEXT
Differential diagnosis of common tremor syndromes
Bhidayasiri
Postgrad. Med. J. 2005;81:756-762.
ABSTRACT
| FULL TEXT
Essential Tremor
Louis
NEJM 2001;345:887-891.
FULL TEXT
|
