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Abstract
Background Psychogenic movement disorders (PMDs) may be difficult to differentiate from organic abnormal movements.
Methods We aimed to characterise the prevalence and clinical features of PMDs resembling tics during the last 3.5 years in our centre.
Results We studied 9 patients (five females) with psychogenic tics representing 4.9% of all 184 patients first evaluated for a PMD during the study period. The mean age at onset was 34.1 years. Lack of premonitory sensations, absence childhood and family history of tics, inability to suppress the movements and coexistence with other PMDs and pseudoseizures were common in our patients. Compared with 273 patients with Tourette syndrome, those with PMDs resembling tics were older: 36.3 versus 18.7 years (p=0.014) at presentation and more frequently female (p=0.030).
Conclusions Movements resembling tics are observed in a small proportion of patients with PMDs. Clinical features can help to differentiate them from organic tics.
- TOURETTE SYNDROME
- SOMATISATION DISORDER
- NEUROPSYCHIATRY
- MOVEMENT DISORDERS
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Introduction
Patients with psychogenic movement disorders (PMDs) may present with a wide variety of clinical phenomenology. While some authors refer to these disorders as ‘functional’ rather than ‘psychogenic’, we prefer the term ‘psychogenic’ for a number of reasons previously extensively discussed,1 ,2 including the fact that these patients are quite ‘dysfunctional’ rather than ‘functional’. Psychogenic tremor, dystonia, myoclonus and gait disorder are among the most frequent presentations of PMDs, but psychogenic movements resembling tics (PMRTs) have been rarely described in the literature.2 Although PMRTs have been reported in 32% of 34 children with PMDs in one report,3 only 17.7% were thought to have documented PMRTs. This series, however, represents an outlier as no documented PMRTs were present in the largest reported series of childhood PMDs involving 54 children4 and in only 6% of another series involving 15 children.5
One possible reason for the relative rarity of documented PMRTs is that they can also be observed in patients with other PMDs,6 and differentiation of PMRTs from organic tics may be difficult as the latter exhibit features frequently observed in PMDs such as sudden onset, distractibility, suggestibility, stereotypic phenomenology, temporary remissions and a fluctuating course.7 The aim of this study was to characterise the clinical features observed in patients with PMRTs.
Patients and methods
We reviewed all cases evaluated in our clinic between January 2009 and July 2012 and diagnosed with PMDs by movement disorders specialists according to the Fahn–Williams diagnostic criteria.8 All patients were videotaped according to a standardised protocol (see online supplementary appendix 1). Videos of cases with a diagnosis of ‘psychogenic tics’ were selected and carefully reviewed to assist in characterisation of the phenomenology. We compared epidemiological aspects between patients with PMRTs and PMDs and Tourette syndrome (TS). We also contrasted features of PMRTs with organic tics. All patients or their legal guardian signed written informed consent for videotaping, approved by the Baylor College of Medicine Institutional Review Board for Human Research.
Results
We studied nine patients with PMDs resembling tics (five females and four males). All these patients fulfilled the diagnostic criteria for clinically established psychogenic MDs (eg, movements inconsistent or incongruent with classic description of MDs associated with other psychogenic signs, multiple somatisation or obvious psychiatric disturbance) according to the Fahn–Williams criteria.8 The mean age at onset of PMRTs was 34.1±17.3 years (range 16–66); no patient had family or childhood history of TS or tic disorder. All nine patients, in addition to their tics, displayed another PMD at the same time or during the follow-up evaluations (table 1).
Clinical features of patients from this series
In addition to motor tics, three patients also produced abnormal sounds and noises that could be considered psychogenic movements resembling phonic tics. Only one patient could volitionally suppress her PMRTs. Premonitory ‘feeling’ preceding the movement was reported in two cases, but this sensation was present only infrequently and inconsistently. No benefit was observed with any pharmacological treatment directed against the PMRTs, although two patients reported a transient improvement with levetiracetam (case 1) and risperidone (case 5). One patient reported worsening of the movements with tetrabenazine, a monoamine-depleting drug. Four out of seven patients eventually had moderate improvement with psychotherapy and stress management therapy.
During the study period, 273 patients with a diagnosis of TS presented to our clinic for a first-time evaluation. Patients with PMRTs were older: 36.3±16.9 versus 18.7±12 years (t=3108; p=0.014) at the time of presentation and more frequently female 55.6% versus 21.5% (p=0.030) compared with TS patients. Furthermore, during the same period, a total of 184 patients with PMDs were initially evaluated in our clinic, and of these patients, those with PMRTs represented 4.9%. No statistically significant differences were observed in age at presentation: 36.3±16.9 versus 43.3±16 years (t=1696; p=0.092) or gender distribution (p=0.243) between patients with PMRTs and other PMDs. We present two illustrative cases.
Case 1
A 20-year-old woman was referred for evaluation of sudden onset stereotyped hyperkinetic movements preceded by episodes of chest pain of unclear aetiology. She also had 4–5 episodes per day of blurry vision and right body shaking lasting 1–2 min, as well as severe mood swings. There was no history of involuntary noise production, loss of consciousness, tongue biting or urinary incontinence. The examination showed repetitive, bilateral shoulder elevations with ipsilateral head oscillation. Premonitory sensations were infrequently reported. The repetitive movements were not suppressible but showed prominent distractibility (see online supplementary video S1). A brain MRI and multiple EEGs were normal. The patient reported prominent stress related to her poor school performances and medical termination of her pregnancy 1 year earlier. She received treatment with levetiracetam elsewhere with only partial and transitory improvement in her movements. Moderate improvement was eventually observed with psychotherapy.
Case 2
A 16-year-old boy was referred to our clinic for evaluation of sudden onset head movements and sniffing diagnosed previously as tics. The movements were preceded by episodes of chest pain, dyspnoea and severe anxiety, followed by seizure-like spells triggered by handwriting with eye closure and generalised body shaking, without loss of consciousness, tongue biting, bladder or bowel incontinence. A video-EEG and a head CT scan were unremarkable. The neurological examination showed frequent, repetitive PMRTs with left torticollis, retrocollis, left hemifacial contractions and sniffing (see online supplementary video S2). The movements were not preceded by any premonitory sensations, were not suppressible, but were markedly distractible. The patient was treated with risperidone elsewhere without clinical benefit. He acknowledged depression and prominent stress related to his studies. Improvement was reported with stress management and psychotherapy.
Discussion
Movements and sounds resembling tics are relatively rare forms of PMDs, including childhood PMDs.9 In our cohort of nine patients, PMRTs represented with PMDs evaluated during a specified study period did not differ in age or gender compared with our other patients with PMDs but were older than our TS population and in contrast to ours and other TS series,7 females outnumbered males. The diagnosis of PMRTs may be challenging because they share several similar features with their organic counterpart. In our patients, the lack of premonitory sensation, inability to transiently suppress the ‘tics’, but prominent distractibility, coexistence of other PMDs or pseudoseizures, poor response to pharmacological therapies but improvement with stress management strongly supports a psychogenic origin of such movements.
The most common cause of adult onset tics is a re-emergence of tics from childhood10; however, none of our mostly adult patients with PMRTs reported tics in their childhood. Family history of TS was also negative. The premonitory sensation is considered a hallmark feature of organic tics, and it is reported in about 90% of TS patients.11 In our series, two patients reported a feeling preceding some of the movements, but this phenomenon was infrequent and inconsistent, and not congruent with typical pre-tic premonitory sensation. Although characteristic of organic tics, premonitory sensations have been reported in patients with presumed psychogenic movements.12
Patients with TS are usually able to transiently suppress their movements, whereas those with PMRTs reported inability to voluntary suppress or ‘hold’ the movements even for a few seconds. We noticed prominent distractibility in all patients with PMRTs, although this feature may also be present in patients with TS. The universal coexistence of other PMDs or pseudoseizures in our patients suggests that this may be an important clue in the diagnosis (table 2).
Differential features between organic tics and PMDs resembling tics
There are several limitations to our study, including a small sample, lack of long-term follow-up, absence of detailed psychiatric evaluation and psychological testing, typically refused by the patient despite our recommendation. Another limitation of our study is the lack of electrophysiological investigations. The bereitschaftspotential (BP), which represents a cortical activation preceding self-initiated movements, has been observed in a small proportion of patients with simple tics13 and can be used to differentiate between psychogenic and non-psychogenic movements. A recent study found the presence of BPs in 25 out of 29 (86%) patients with psychogenic jerks and in 6 out of 14 (43%) patients with organic tics.14 Those with psychogenic jerks had a significantly higher proportion of early BPs (potential ≤1000 ms before movement onset) compared with TS patients. Furthermore, a significantly fewer psychogenic patients had BPs preceding voluntary wrist extension. Although the BPs showed a low specificity for the diagnosis of psychogenic jerks and tics, 0.68 and 0.26, respectively,14 these findings suggest that combined clinical and neurophysiological studies might aid in the differentiation between PMRTs and organic tics. Further studies are need to better understand how to interpret BP in patients with TS and whether they represent a neurophysiological correlate of premonitory sensations.
In conclusion, PMRTs may be present as part of the broad phenomenology of PMDs. Several clinical features such as lack of premonitory sensation, suppressibility and family history, coupled with prominent distractibility and coexistence with other PMDs, can help to differentiate them from organic MDs. Appropriate diagnosis, insight-oriented psychotherapy, treatment of underlying depression, anxiety and other psychiatric conditions should not only improve the quality of life of these patients but may facilitate a speedy and lasting recovery.15
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Files in this Data Supplement:
- Data supplement 1 - Online appendix
- Data supplement 2 - Online video 1
- Data supplement 3 - Online video 2
Footnotes
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Contributors JFBC gathered the data, conceptualised and wrote the first draft of the manuscript. JJ gathered the data, conceptualised and reviewed the manuscript.
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Competing interests None.
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Patient consent Obtained.
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Ethics approval Approval was obtained for videotaping and presentation in a scientific journal, by the Baylor College of Medicine Institutional Review Board for Human Research.
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Provenance and peer review Not commissioned; externally peer reviewed.