Distinguishing psychogenic and essential tremor
Introduction
The most common cause of tremor, affecting up to 5% of people over the age of 65, is essential tremor (ET) characterized by a progressive 4–12 Hz postural and kinetic tremor [1], [2]. Ninety percent of cases involve the hands; additional affected areas include the head, voice, legs, and tongue. Over time, patients tend to exhibit a lower frequency tremor with larger amplitude and poorer response to medications, leading to more disability [3]. Psychogenic movement disorders (PMD) comprise 4.1% of all patients seen in our movement disorders clinic [4], [5]. PMD can be challenging to properly diagnose [6], [7] given the potential for complex phenomenology including dystonia, [8], [9] myoclonus, [10] tics, [11] hemifacial spasm, [12] parkinsonism, [13], [14] paroxysmal dyskinesia, [15] palatal tremor, [16], [17] and gait dysfunction [18]. Psychogenic tremor (PT) is the most common PMD, accounting for about 25% of all cases [4]. Physical examination techniques such as entrainment, distraction, and suggestibility have been used to aid differentiation of PT from organic tremors such as ET. Electrophysiological studies are also used, but rarely accessible to practitioners. The primary aim of this study is to determine which clinical features most reliably facilitate the diagnosis of PT and help clinicians differentiate this PMD from ET.
Section snippets
Methods
The Baylor College of Medicine (BCM) Institutional Review Board approved this protocol. All consecutive patients diagnosed with definite ET or probable PT were approached about participating in this study and signed an approved consent form before enrollment. ET was diagnosed according to standardized criteria formulated by the Tremor Investigational Group [19]. The diagnosis of PT was based on the Fahn and Williams diagnostic criteria with particular attention to “clues”: false weakness, false
Results
Of 45 patients, 33 met clinical criteria for definite ET with a mean age of 56.8 ± 17.0 years and 12 met clinical criteria for probable PT with a mean age of 42.5 ± 11.0 years (Table 3). This difference in age at the time of evaluation was statistically significant (p = 0.003), but there was no difference in the age at onset of tremor between the two groups. Duration of tremor, however, was significantly longer in the ET group (28.5 ± 7.8 years) compared to the PT group (7.8 ± 4.0 years) (p = 0.001). PT
Discussion
Our findings are consistent with previous reports of clinical features differentiating PT and ET, [22] although this is the first study to systematically compare the effects of various provocative tests on organic and psychogenic disorders using a standardized protocol. Specifically, we found sudden onset, short duration, and spontaneous remission of tremor as suggestive of PT. The development of a moderate postural and kinetic tremor over a relatively short period of time should raise one's
Acknowledgement
The authors wish to thank all patients for their participation. This study was in part supported by the National Parkinson Foundation.
References (34)
Essential tremor
Lancet Neurol
(2005)- et al.
Long-term prognosis of patients with psychogenic movement disorders
Parkinsonism Relat Disord
(2006) - et al.
Psychogenic movement disorders
Lancet Neurol
(2006) - et al.
Exploring the relationship between essential tremor and Parkinson's disease
Parkinsonism Relat Disord
(2007) - et al.
How common is the most common adult movement disorder? Estimates of the prevalence of essential tremor throughout the world
Mov Disord
(1998) Essential tremor frequency decreases with time
Neurology
(2000)- et al.
Psychogenic tremor: long-term outcome
CNS Spectr
(2006) Psychogenic movement disorders: a crisis for neurology
Curr Neurol Neurosci Rep
(2006)Psychogenic dystonia: a review of 18 cases
Can J Neurol Sci
(1995)- et al.
The syndrome of fixed dystonia: an evaluation of 103 patients
Brain
(2004)
Psychogenic myoclonus
Neurology
Psychogenic movement disorder (pseudo-tics) in a patient with Tourette's syndrome
J Neuropsychiatry Clin Neurosci
Psychogenic hemifacial spasm
J Neuropsychiatry Clin Neurosci
Psychogenic parkinsonism
Arch Neurol
Psychogenic parkinsonism: a combination of clinical, electrophysiological, and [(123)I]-FP-CIT SPECT scan explorations improves diagnostic accuracy
Mov Disord
Psychogenic paroxysmal dyskinesia following paroxysmal hemidystonia in multiple sclerosis
Neurology
Psychogenic palatal tremor
Mov Disord
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