Download Functional (psychogenic) movement disorders: merging mind and

Review
Functional (psychogenic) movement disorders: merging
mind and brain
Mark J Edwards, Kailash P Bhatia
Lancet Neurol 2012; 11: 250–60
Sobell Department of Motor
Neuroscience and Movement
Disorders, UCL Institute of
Neurology, London, UK
(M J Edwards PhD,
Prof K P Bhatia MD)
Correspondence to:
Prof K Bhatia, Sobell
Department, UCL Institute of
Neurology, Queen Square,
London WC1N 3BG, UK
[email protected]
Functional (psychogenic) movement disorders (FMD) are part of the wide spectrum of functional neurological
disorders, which together account for over 16% of patients referred to neurology clinics. FMD have been described as
a “crisis for neurology” and cause major challenges in terms of diagnosis and treatment. As with other functional
disorders, a key issue is the absence of pathophysiological understanding. There has been an influential historical
emphasis on causation by emotional trauma, which is not supported by epidemiological studies. The similarity
between physical signs in functional disorders and those that occur in feigned illness has also raised important
challenges for pathophysiological understanding and has challenged health professionals’ attitudes toward patients
with these disorders. However, physical signs and selected investigations can help clinicians to reach a positive
diagnosis, and modern pathophysiological research is showing an appreciation of the importance of both physical
and psychological factors in FMD.
Introduction
Functional (psychogenic) movement disorders (FMD)
are part of the spectrum of functional neurological
disorders, some of the most prevalent disorders seen in
neurological practice.1 In common with other functional
disorders, there is an absence of appropriate healthservice provision and research interest for FMD, despite
their prevalence. These disorders occupy a grey area
between neurology and psychiatry—often with neither
specialist group willing to take charge—which has
resulted in what has been described in relation to FMD
as a “crisis for neurology”.2
There are three rationales behind this Review. First,
there have been notable developments in diagnostic
techniques, pathophysiological understanding, and treatments in FMD, which together represent a substantial
advance in knowledge. Second, we wish to highlight an
important shift that has taken place in approaches to
functional disorders in general: the historically influential
explanation for symptoms triggered by emotional trauma
(and the research and treatment agendas that emerge
from this explanation) has been challenged. Third,
because of the enormous health-care and social-care
costs associated with functional symptoms such as FMD,
health professionals and medical scientists need to take
an active interest in keeping up to date with best practice
in diagnosis and management. FMD have traditionally
been thought of as the most difficult of the functional
neurological disorders to diagnose and manage, but we
will show that they need not always carry such a
reputation.
Terminology and definition
When experts cannot agree on a unified terminology for
a disorder, there is likely to be a fundamental problem
with understanding the underlying pathophysiology.
This difficulty in understanding is certainly present for
psychogenic disorders, including FMD, for which there
are many descriptive terms to choose from (panel 1).
The choice of term is not a trivial issue, because it
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directly affects case definition, diagnosis, treatment,
research agenda, and explanations of illness that we give
to patients.
Some terms, such as psychogenic, conversion, or
somatisation, directly suggest that the cause of physical
symptoms is psychologically mediated. Conversion and
somatisation are operationalised diagnoses that specifically need the presence of a psychological triggering
factor and exclusion of feigning. However, for most
movement disorder clinicians, the presence of a
psychological triggering factor is not a requirement for
diagnosing a patient with FMD,3 and the difficulties of
routinely excluding feigning in clinical practice are
complex.4 We also show later that recent epidemiological
studies question the relevance of psychological triggers
in most patients with FMD.5 However, other terms also
have their difficulties. For example, does a disorder
that is medically unexplained simply mean that we
have not yet found the medical explanation, and with
advancement of medical knowledge it will become a
medically explained disorder? What level of medical
explanation do we need for a disorder to be medically
explained? The term hysteria comes with substantial
historical baggage, but some movement disorder
specialists, including the most eminent of recent times,
David Marsden, have argued passionately that the term
should be retained.6 The term functional also has a
long and distinguished neurological history, but some
argue that it has lost its meaning over time and is now
too broad a term to be helpful.7
Patients are directly affected by the diagnostic labels we
give them. Stone and colleagues8 explored this issue with
unselected neurology outpatients and found that many
terms were judged by patients as suggesting that the
doctor thought their symptoms were “put on” or “all in
the mind”. Hysteria came out badly on this assessment,
but so did the term medically unexplained. The term
psychogenic was not specifically assessed, but psychosomatic was and was rated negatively. Functional was the
term most acceptable to patients.
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Review
We use the term functional in this Review. The origins
and chequered history of this term have been discussed
in detail by Trimble.7 He argues that the original
physiological use of the term as a disturbance of
functioning of the nervous system where the cause has
yet to be defined has value, in contrast to its use as a
“polite eponym” for a psychiatric disorder.7 We accept
that there are difficulties in using this term as a
replacement for other terms such as psychogenic.
Although in our view this term accurately reflects the
state of the evidence regarding the pathophysiology of
psychogenic disorders, this use does also mean that the
word functional is used to apply to the functional
disturbance that occurs in this patient group only,
and not in patients with, for example, headache.
Unfortunately, this debate cannot be solved in this
Review, and we recognise the insufficiency of present
terminological options. In clinical practice, we use the
term functional, because it is the term most acceptable
to patients and does not presuppose a cause for
symptoms that is unproven. We specifically define this
disorder by its clinical appearance, rather than by any
causative speculation as a movement disorder that is
significantly altered by distraction or non-physiological
manoeuvres (including dramatic placebo response) and
that is clinically incongruent with movement disorders
known to be caused by neurological disease.
Epidemiology, quality of life, and cost
The subject of this Review represents an important
issue because of its prevalence and effect on quality of
life and health-care economics. FMD are part of the
wide spectrum of functional or psychogenic neurological
symptoms, which together account for 16% of new patients attending neurology outpatients’ clinics.1 Accurate
estimates of prevalence of FMD are hampered by case
definition and the setting of the clinic from which
cases are ascertained, and range between 2 and 20% of
patients attending movement disorder clinics.9,10 These
disorders cause an impairment in quality of life that
is similar to, and in some aspects worse than, that
experienced by patients with Parkinson’s disease.11 No
studies have specifically addressed the economic
burden of FMD but, given the level of disability reported
by patients in the long term (see Prognosis section),
there are probably substantial associated health and
social care costs. In a large study of patients with
functional neurological symptoms (n=1144) who were
followed up for 1 year, at least 50% had stopped working
and more than one-quarter were receiving illnessrelated financial benefits;12 the economic burden for
those with FMD is unlikely to differ from this. UK
estimates for the yearly costs associated with workingage patients with “medically unexplained symptoms”
are approximately £18 billion,13 slightly more than the
annual cost associated with dementia for patients of all
ages in the UK.14 Women are more often affected by
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Panel 1: Terms commonly used to describe psychogenic
disorders and their implications
Psychogenic
• Suggests psychological causation
Conversion disorder
• Operationalised within DSM: requires an identified
psychological triggering factor for diagnosis
Somatisation disorder
• Operationalised within DSM: requires presence of
multiple physical symptoms including one conversion
neurological symptom
Medically unexplained symptoms
• Suggests that a medical explanation might one day
be apparent
• Could refer to many medical symptoms that are not
thought to be psychogenic, but still are not of a
known cause
Functional
• Broad term suggesting a functional rather than a
structural deficit, which could apply to several
neurological disorders not regarded as psychogenic but
where structural pathology is absent, eg, migraine
Hysteria
• Historical term that carries substantial stigma in society
and implies a link between symptoms and the uterus
Non-organic
• Defines the condition by what it is not; the term organic is
itself not well defined
DSM=Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, American
Psychiatric Association.
FMD than men, and mean age at onset in different
studies ranges from 37 to 50 years.9,10 FMD are also
reported, but not commonly, in children15 and in the
elderly.9,10
Clinical features
Several historical features and examination findings
are commonly noted in patients with FMD regardless
of the movement disorder phenomenology. These
features are not diagnostic of FMD, but can be helpful
as part of the diagnostic process. Patients often describe
the sudden onset of symptoms, which might be
precipitated by a physical event (eg, injury or illness).9,10
Symptoms can rapidly progress to become severe—a
pattern that is unlike the slow progressive course of
most movement disorders.9,10 Patients might report
marked variability in symptom severity, including
complete remissions and sudden recurrences. The
phenomenology of the movement disorder might shift
over time. Patients might have a history of other
functional symptoms. Neurological signs apart from
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the movement disorder can be consistent with
functional illness, for example Hoover’s sign (leg
paresis), give-way weakness, and non-anatomical
patterns of sensory loss.9,10 The co-occurrence of
functional and organic movement disorders might be
expected, given the common co-occurrence of other
functional disorders with organic disorders, for example
epilepsy and non-epileptic seizures.16 However, hard
evidence for the prevalence of this phenomenon is
limited.17,18
Functional tremor
Functional tremor (FT) is the commonest presentation of
FMD, accounting for at least 50% of patients.9 Commonly,
the historical features are as outlined earlier, with sudden
onset, variability in severity with remissions, and variability
in the body part affected. Most patients have a tremor that
is present (or at least can be present at different times) at
rest, in posture, and during action, which is an unusual
pattern for organic tremor. Tremor can occur in any body
part; the hands and arms are most frequently involved,
but tremor of the head, legs, or even palate can also occur.
By contrast with patients with organic tremor, patients
with FT often direct clear visual attention towards their
affected limb during examination.19
The key clinical feature that helps to differentiate
FT from organic tremor is that FT changes with the
level of attention towards the affected limb. This can be
appreciated during history taking as fluctuation in
tremor severity (or even presence) while the patient’s
attention is engaged. Conversely, FT commonly worsens
during examination. Specific examination manoeuvres
can be used to distract attention away from the
tremoring limb; some formal assessments of specificity
and sensitivity have been done on these manoeuvres
clinically,20 and more extensively with electrophysiological
tremor recordings.21–25 Thus, tremor may change with
cognitive distraction tasks or tapping at different
frequencies (it may entrain to the tapping frequency,
shift in frequency, or stop altogether; or the patient
might inexplicably be unable to undertake the required
tapping movement correctly);21,22 pause with ballistic
movement of the other limb (figure 1);23 or paradoxically
worsen with loading.24 The specificity and sensitivity of
some of these tasks have been investigated (without
tremor recordings) in patients with FT compared with
those with essential tremor; tapping tasks had the
highest sensitivity and specificity (72·7% and 73·3%,
respectively).20 In a head-to-head study, we compared
these techniques with tremor recordings in FT and a
AccZL
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AccYL
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0·04
0·02
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AccXL
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Pause in tremor
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AccXR
AccYR
AccZR
0·05
0
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1372
1374
1376 1378 1380 1382 1384 1386 1388 1390 1392 1394 1396 1398 1400 1402 1404 1406 1408 1410 1412
Time (s)
Figure 1: Tremor recordings in a patient with functional tremor
Tri-axial accelerometry recordings from an accelerometer attached to the tremoring hand (top three traces) and to the unaffected hand (bottom three traces). The
patient is undertaking rapid reaching movements to a target with the unaffected hand, which produces brief pauses in the tremor in the other hand.
Acc=acceleration. X=x axis. Y=y axis. Z=z axis. R=right. L=left.
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range of organic tremor disorders (Parkinson’s disease,
essential tremor, dystonic tremor, and neuropathic
tremor).25 We found that no single measure had
sufficient specificity and sensitivity to differentiate FT
from organic tremor. This finding is probably due to
the different mechanisms for tremor generation in FT,
with some patients generating tremor primarily by cocontraction, which is not readily distractible by tapping
tasks.24 Cognitive distracter tasks were poor discriminators between organic tremor and FT. A cutoff
score was devised by combining several of these
measures, which, if validated in a prospective study,
could provide a laboratory-supported level of diagnostic
certainty (table).
Functional dystonia
Functional dystonia is the second most common
presentation in patients with FMD.9 There are
substantial differences of opinion between experts
regarding the diagnosis of functional dystonia. These
differences are not helped by the history of dystonia in
general: patients now classified as having organic
dystonia were, until the 1980s, commonly classified as
having hysteria. Advances in genetics have led to
recognition of the phenotypes of primary idiopathic
dystonia, which have typical ages of onset, courses, and
distributions of dystonia. For example, DYT1 generelated primary dystonia starts before age 25 years,
often affects the legs at onset, and can spread over a few
years after onset to cause generalised dystonia.26 By
contrast, late-onset primary dystonia affects the craniocervical region (spasmodic torticollis is the most
common form) and tends to remain focal.26 This
identification of distinct phenotypes has made easier
the recognition of secondary dystonic (including
functional) disorders, which have presentations
incongruous with primary dystonia phenotypes.
Patients with functional dystonia typically present with
fixed abnormal postures accompanied by severe pain
similar to that noted in chronic regional pain syndrome
type 1 (CRPS1). Most patients with functional dystonia
are young women and the usual trigger is a minor
peripheral injury, but the disorder is sometimes
spontaneous. Such patients (who might also be classed
as having “causalgia-dystonia”27 or “tonic dystonia of
chronic regional pain”28) may experience spread of
symptoms to other body parts without further injury.
Limbs are usually involved, but fixed dystonia affecting
the neck or jaw has also been reported.29
Physical examination manoeuvres can be used to
show with certainty whether attention is playing a key
part in symptom generation in functional tremor;
however, to show the same level of certainty in fixed
dystonia is difficult. One might argue that this difficulty
occurs because fixed dystonia is not a functional
disorder, but to state that maintenance of postures does
not need a similar level of attention as maintenance of
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tremor would also be reasonable. However, in some
patients a brief give way of muscle activity in the
affected limb will be felt when the patient is distracted.
In support of the functional label for fixed dystonia,
symptoms may resolve with multidisciplinary rehabilitation with an emphasis on cognitive-behavioural
therapy,30 the disorder may co-exist with other more
clearly defined psychogenic disorders,29,30 and marked
(curative) placebo responses have been reported.31
However, some,32 but not all,33 research electrohysiological tests suggest similarities between patients
with fixed dystonia and those with organic dystonia,
although these tests are all subject to confounding from
muscle activity, attention, and anxiety. Maintenance of a
fixed posture has been hypothesised to produce
secondary changes in central body schema,34 and these
changes might contribute to pain and other unusual
features, such as the seeking of limb amputation by
some patients.35
Functional myoclonus
Functional myoclonus is reported in about 20% of
patients with FMD.9 As might be expected in patients
with intermittent movements, distractibility can be
difficult to demonstrate on examination. Electrophysiological tests can therefore be of substantial
diagnostic help to clinicians.36 Simple electromyography
(EMG) recordings can be used to assess EMG burst
duration: consistent EMG bursts of less than 75 ms do
not occur in functional myoclonus. However, the
converse is not true, because some forms of organic
myoclonus are associated with long-duration EMG
bursts. Electrophysiological features associated with
cortical myoclonus (giant somatosensory evoked
potentials, electroencephalogram [EEG] spike 20 ms
Points
Incorrect tapping performance at:
1 Hz
1
3 Hz
1
5 Hz
1
Entrainment, suppression, or pathological frequency shift at:
1 Hz
1
3 Hz
1
5 Hz
1
Pause or 50% reduction in amplitude of tremor with ballistic
movements
1
Tonic activation before tremor onset
1
Coherence of bilateral tremors
1
Increase of TP (as surrogate of tremor amplitude)
1
Cutoff score for functional tremor
≥3
TP=total power of the spectra between 1 and 30 Hz. Data from Schwingenschuh
and colleagues.25
Table: Suggested electrophysiological test criteria for diagnosis of
functional tremor
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Onset of movement
20
Potential (μV)
10
0
–10
–20
–2500
–2000
–1500
–1000
–500
0
Latency (ms)
Figure 2: Electroencephalogram recordings from a patient with functional myoclonus
A slow rising potential can be seen, which starts around 1 s before movement.
before jerks) would not be expected in functional
myoclonus. The most useful diagnostic test in patients
with suitable symptoms (see below) is EEG–EMG backaveraging—a method for assessing cortical activity
shortly before movement (figure 2). In healthy people
undertaking a self-paced voluntary movement, a slow
rising potential is seen in the EEG starting about 1·5 s
before movement and peaking just before movement:
this is the pre-movement potential, or Bereitschaftspotential.36 This potential can be recorded in patients
with functional myoclonus and is not seen in people
with organic myoclonus. There are technical limitations
to this test: at least 30 jerks need to be recorded, so
patients must have a reasonable number of jerks within
the recording time; and pre-movement potentials are
often difficult to record in patients with very rapid jerks
(more than one every 3–5 s), although distractibility is
often easy to indentify in such patients clinically. Premovement potentials have been reported in patients
with tics,37 but not consistently.38 Two groups have independently reported that most patients diagnosed with
idiopathic spinal segmental or propriospinal myoclonus
(the latter characterised by flexion jerks of the abdomen)
have pre-movement potentials before jerks and are
therefore best characterised as functional.39,40
Other functional movement disorders
Pure functional gait disturbance accounts for about 6%
of patients with functional movement disorders, but an
abnormal gait is a common feature in patients with
other FMD.41 Various gait patterns are described, but a
key feature of most of these patterns is that the patient
does not seem to adapt to the gait problem they
complain of in an optimum way.42–44 For example,
patients who complain of unsteadiness might walk with
a narrow base or might adopt uneconomic postures,
which are apparently compensatory for the gait
disturbance but would seem objectively to make it
worse.41 Some patients have objectively very good
balance while subjectively complaining of poor balance;
such patients shift their centre of gravity by pivoting
from side to side at the waist on a narrow base without
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falling, thus showing excellent balance. This pattern
has been termed the “walking on ice” gait.44 Another
common pattern of functional gait disturbance is a
monoplegic dragging gait, where the affected leg is
dragged behind the patient, typically with the medial
surface of the foot in contact with the floor and the leg
externally rotated.45 This is quite different from the
circumducting gait typically seen in patients with
organic hemiplegia. So-called bizarre patterns of gait
are seen in organic movement disorders such as
Huntington’s disease and generalised dystonia, and
care needs to be taken in reaching a diagnosis with
regard to unusual gait disturbance.
Functional parkinsonism, chorea, and tics are rarely
reported.9 Most patients diagnosed with functional
parkinsonism actually have a functional resting tremor
rather than other features (such as slowness of movement) that mimic parkinsonism.46 Dopamine transporter scans can be helpful to a limited extent if
diagnostic uncertainty exists. Dopamine transporter
scans are normal in patients with functional
parkinsonism but also in organic parkinsonism due to
postsynaptic dopaminergic deficit, such as druginduced parkinsonism. Paroxysmal functional movement disorders are rarely reported but do occur.9 They
may be under-recognised because patients might
instead be diagnosed with functional non-epileptic
seizures. Clinicians need to be familiar with the range
of triggers, attack durations, and attack frequencies that
occur in organic paroxysmal movement disorders to
help them to differentiate patients with functional
attacks with confidence and to exclude epilepsy by EEG
measurement during an attack if necessary. There is no
substitute for seeing an attack, and the video facility
available on many modern mobile phones makes it
easier for patients’ relatives to record an attack for
viewing by the physician.
Diagnostic criteria
We emphasised earlier that the diagnosis of FMD
should as much as possible be a positive diagnosis. It
should not be a diagnosis of exclusion, nor a diagnosis
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made on the basis of co-existence of a movement disorder
with psychological disturbance. Co-existent psychological
disturbance is common throughout organic neurological
disease and is not an adequate symptom on its own to
diagnose a psychogenic disorder.47
Operationalised diagnostic criteria for functional
movement disorders include the Fahn-Williams
criteria48 (the most widely used), the Shill-Gerber
criteria,49 and a recent revision of the Fahn-Williams
criteria proposed by Gupta and Lang (panel 2).47 All
these criteria have as a key element a gradation of
certainty of diagnosis; for example, in the Fahn-Williams
criteria the gradation is documented, clinically
established, probable, and possible. Various alterations
to the Fahn-Williams criteria have been suggested,
including a merging of documented and clinically
established categories into one category of clinically
definite; the removal of the possible category; and the
addition of laboratory tests to produce a category of
laboratory supported.47 The Shill-Gerber criteria have
been criticised for being so heavily weighted towards
historical information that the diagnosis of FMD could
possibly be made with little reference to the clinical
characteristics of the movement disorder.50 These
criteria also place weight on the notion of disease
modelling, in which experience of a disease in a family
member, acquaintance, or via work provides a model
for patients to produce functional symptoms. This
notion is difficult to investigate (eg, the quantification
of all potential disease models to which a person has
been exposed would seem to be very difficult), and
therefore its place in diagnostic criteria seems
questionable according to the available evidence.
The Fahn-Williams and Shill-Gerber criteria have
recently been subjected to assessment of inter-rater
reliability.51 There was only poor (Shill-Gerber) to
moderate (Fahn-Williams) inter-rater reliability for
probable and possible categories, with good agreement
for the clinically definite category.
Pathophysiology
The earlier discussion of terminology shows a historical
emphasis on psychological causation in FMD, as with
other functional disorders. Psychiatric formulations
based on late 19th and early 20th century concepts of
conversion, somatisation, and dissociation still form
the basis for psychiatric diagnoses in these disorders
and, by extension, ideas regarding pathophysiology.52
However, patients with psychogenic disorders in
general, including those with FMD, do not have the
expected rates of psychological trauma, either at the
onset of physical symptoms or in the past.5,53 This
finding presents a problem for those who emphasise
such factors as important pathophysiologically. This
problem has traditionally been solved, in a rather
circular argument, by suggesting that recall of such life
events is repressed by patients and therefore is not
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Panel 2: Fahn-Williams and Gupta-Lang criteria for
diagnosis of psychogenic movement disorders
Fahn-Williams criteria48
Documented
Persistent relief by psychotherapy, suggestion, or placebo has
been demonstrated, which may be helped by physiotherapy;
or the patient was seen without the movement disorder
when believing himself or herself unobserved.
Clinically established
The movement disorder is incongruent with a classical
movement disorder or there are inconsistencies in the
examination, plus at least one of the following three: other
psychogenic signs, multiple somatisations, or an obvious
psychiatric disturbance.
Probable
The movement disorder is incongruent or inconsistent with
typical movement disorders or there are psychogenic signs
or multiple somatisations.
Possible
Evidence of an emotional disturbance.
Laboratory supported definite
Not included in this classification.
Gupta and Lang proposed revisions47
Clinically definite
Includes Fahn-Williams documented and clinically
established categories, and also includes movement
disorders that are incongruent with a classical movement
disorder or for which there are inconsistencies in the
examination, without the need for the additional presence
of psychogenic signs, multiple somatisations, or an obvious
psychiatric disturbance.
Probable
Not included in this classification.
Possible
Gupta and Lang question the utility of this category. They
suggest it could be used to include those with movement
disorders congruent or consistent with a classical
movement disorder but where there are additional
psychogenic signs, somatisations, or evidence of emotional
disturbance. However, they suggest that this category may
then include patients who are different
pathophysiologically from those with true psychogenic
movement disorders.
Laboratory supported definite
Presence of data from electrophysiological tests that prove
the presence of a psychogenic movement disorder
(primarily evidence of pre-movement potentials before
jerks or data from tremor studies).
available for report. Although this repression may
occur in some patients, the suggestion is largely
untestable.
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The key clinical feature that separates patients with
FMD from those with organic movement disorders is
that the movements have features that one would
usually
associate
with
voluntary
movement
(distractibility, resolution with placebo, and presence of
pre-movement potentials), but patients report them as
being involuntary and not under their control. There
seem to be just two logical explanations for this feature:
either movements are deliberately feigned or there must
be a brain mechanism that allows voluntary movement
to occur but to be experienced subjectively as involuntary.
Understanding this mechanism would seem to be key
to understanding the development of symptoms and
their treatment.
Although study of subjective experience of movement
might seem impossible, cognitive neuroscience has
revealed the existence of mechanisms within the
brain that confer a sense of intention and a sense of
agency to movement, and examples of organic brain
disease in which such processes are disrupted.54
Functional imaging recorded in patients during an
episode of functional tremor or when the same patients
were voluntarily mimicking their tremor showed
hypoactivation of the temporoparietal junction during
the psychogenic tremor.55 This area is thought to be an
important comparator region, comparing actual with
predicted sensory feedback. The suggestion is that
hypoactivity might represent a failure to match the actual
and predicted sensory feedback, producing a feeling of
involuntariness associated with movement.55 Linked
with this finding, we have reported that patients with
functional tremor do not have the normal sense of
intention that is associated with voluntary movement.56
Another functional imaging study in FMD noted
abnormally strong amygdala–supplementary motor area
connectivity when patients were presented with
emotionally valent stimuli and abnormally weak
supplementary motor area–prefrontal cortex connectivity
in a reaction time task.57 A hypothesis arising from this
work and a further functional imaging study in FMD58 is
that emotionally arousing events might trigger
movement controlled by the supplementary motor area
that is functionally disconnected from top–down control
by the prefrontal cortex.
In a recent study that compared patients with
functional tremor to those with organic tremor, we
compared self-completed diaries in which patients rated
the amount of the waking day they felt they had tremor
with the results of continuous tremor recordings from
a wrist-worn actigraph.59 Patients were all aware of the
purpose of the study, as confirmed in a post-study
questionnaire. Patients with organic tremor tended to
over-rate their tremor (by about 20%) in diaries
compared with the tremor watch recordings. Patients
with functional tremor over-rated their tremor by a
significantly higher amount (more than 65%; p=0·0001),
and had on average only 30 min of tremor per day. We
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have interpreted this finding within a Bayesian
framework as a dominance of prior expectancy over
sensory data.59
These studies all provide results that would be
unexpected in patients feigning symptoms, although
they do not amount to an aid to diagnose feigning of
symptoms. However, these studies do provide examples
of research in functional disorders that look beyond the
rigid framework that has provided a causal model for
symptoms on the basis of emotional trauma alone.
There has been a wider rebalancing of attitudes toward
functional disorders, so that they are considered within
a biopsychosocial model, not just a psychosocial one.
This change in attitude might prompt a search for
psychological factors of causative importance that are
not solely related to emotional trauma. This type of
search has been underway for some decades in other
disorders (eg, schizophrenia) once regarded as mental
disorders but in which great importance is now given to
understanding the biological basis of the disorder. The
old dichotomy between mental and brain disorders has
increasingly been swept away by the progress of
cognitive neuroscience and, although long overdue,
this process is now affecting views of functional
neurological disorders. To regard FMD and other
functional disorders as just brain disorders would also
be incorrect, and so a combined approach is necessary
that integrates societal and psychological factors with
our present knowledge of the biology of brain function.
This process might not just lead to better understanding
of FMD, but might also improve our understanding of
the human brain.
Management
There are limited studies available on which to base
management decisions in FMD. It seems reasonable to
presume that treatment of FMD can be informed by data
regarding treatment of other functional neurological
conditions, in particular those that involve motor
symptoms.
In our view, the most important first steps in a
successful treatment approach are effective communication of the diagnosis and the provision to patients
and their families of a rational model within which
to understand the physical symptoms. In light of the
earlier discussion regarding diagnosis, we emphasise
the positive ways in which the diagnosis has been made
rather than falling back on explanations based on
normal test results. We try to introduce the role of
psychological factors in their proper context and do not
insist on extensive exploration for underlying psychological trauma. Patients with FMD are vulnerable to
unscrupulous medical and health practitioners, particularly over the internet.60 There are some useful web
resources that can help to support understanding of the
diagnosis for patients with functional symptoms, and we
direct patients towards these.61
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Review
There is no evidence to support the use of drugs
traditionally used for the treatment of organic
movement disorders in patients with FMD. Medical
and surgical interventions are often harmful to patients
with FMD,30,35 and part of successful treatment is
removal of unnecessary medications and avoidance of
unnecessary tests and surgical treatments. The only
exception to this is provided by studies of intrathecal
baclofen in patients with fixed dystonia and CRPS1, but
these results carry important caveats. An initial
controlled study in a small group of patients gave
impressive results,62 but a follow-up study of a larger
group of patients63 found treatment-related complications to be high, although a beneficial effect was
seen in many patients. The difficulty with both studies
is that the systemic effects of intrathecal baclofen
cannot be adequately controlled, and therefore patients
are systematically unmasked to the intervention. We
would urge caution with the use of this invasive
treatment given evidence of dramatic placebo response
of patients with fixed dystonia to other treatments.31 We
have highlighted earlier the difference of specialist
opinion regarding the nature of the disorder in patients
with fixed dystonia. Despite this difference in opinion,
there is no need to delay effective management, because
delay is associated with worse outcome and, in some
patients, the development of irreversible contractures.30
The key component of treatment is rapid early mobilisation with suitable holistic management of pain (with
emphasis on techniques used in CRPS1 such as
desensitisation). Surgical intervention and prolonged
immobilisation should be avoided.
There is some evidence that psychological intervention,
in the form of either psychodynamic psychotherapy64 or
more pragmatic symptom-based cognitive-behavioural
therapy,65 might be helpful for patients with functional
motor symptoms, including FMD. These techniques are
only applicable to those patients who accept that
psychological or behavioural interventions are valid
methods of treatment for their physical symptoms. Likewise, there is evidence that a subset of patients who are
willing to take antidepressants (in this study, those
diagnosed with primary conversion disorder and not
those with somatisation disorder) can benefit from this
treatment.66
Physical rehabilitation has face validity as a treatment
to manage motor symptoms, but there are few trials
upon which to base opinion. There is evidence that a
multidisciplinary approach combining physical and
psychological treatment can be effective for some
patients.30 This intensive (often inpatient) treatment is
expensive and will always have limited availability. In a
retrospective, case-control study, a brief (5 day) intensive
inpatient physical therapy programme produced major
self-rated improvement in symptoms in more than 60%
of participants (n=48) compared with 22% of control
individuals (n=32) after 2 years of follow-up.67 This
www.thelancet.com/neurology Vol 11 March 2012
study used an explanatory model of symptoms that was
deliberately physical (abnormal motor learning) and,
although psychological factors were addressed, the
focus was maintained on physical symptoms and
treatment. Benefit has also been reported from a simple
12-week programme of supervised low-to-medium
intensity walking in patients with FMD.68 Such findings,
if confirmed by further studies, suggest that physical
interventions (perhaps combined with symptomfocused cognitive-behavioural techniques65) may provide
an effective and acceptable means of symptom
management.
Placebo interventions can have strong effects in patients
with FMD,31 but evidence for long-term benefit is absent
and the ethics of such treatments are hotly debated.69 In
this vein, transcranial magnetic stimulation has been
reported to be of benefit in patients with FT, with
investigators suggesting a possible real effect of
stimulation.70 However, the unmasked nature of the
intervention makes a placebo effect likely.
Prognosis
Long-term follow-up studies are confounded by the
manner in which cases are diagnosed—typically by
tertiary movement disorder clinics where patients with
brief transient symptoms will be missed. In these
studies, about half of patients report some improvement
in symptoms at long-term (3–5 years) follow-up,
although most patients remain out of work due to
illness.71,72 Good prognostic features include a short
duration of illness, perception by the patient of effective
management by the clinician, and the presence of
depression or anxiety (which is therefore amenable to
psychiatric treatment).71,72
Future work
This Review reports several areas in which evidencebased knowledge is limited. With specific reference to
FMD, we wish to highlight the following areas and
important questions.
Diagnostic tests and criteria
The discussion of FT shows how clinical (and simple
electrophysiological) tests can be used to make a
positive diagnosis. This process urgently needs to be
extended to other movement disorders, in particular to
patients with abnormal postures. If successful, use of
this process could lead to new diagnostic criteria, which
would be based on these positive clinical features and
rely less on associations with psychological factors or
with the notion of (unspecified) incongruity with
organic movement disorders.
Research
By contrast with some functional disorders in which
symptoms are subjective (pain, sensory loss, or disturbance), functional motor disorders such as FMD provide
257
Review
Search strategy and selection criteria
For the purposes of this Review, we searched Medline
between 1975 and December, 2011, for articles with the
keywords “psychogenic”, “functional”, “conversion”,
“movement disorder”, “parkinsonism”, “tremor”,
“dystonia”, “myoclonus”, “chorea”, “tics”, and “gait”. We
selected papers relevant to diagnosis, treatment, and
pathophysiology.
researchers with a measurable entity that reflects the
underlying symptom. We suggest, therefore, that patients
with functional motor disorders, in particular FMD, are
the natural group to include in future research studies.
Research studies such as those reviewed herein show
that such patients can participate in research and that
informative results can be obtained.
Treatment
There is a clear and urgent need for treatment studies
in FMD and other functional neurological disorders.
The acceptability of treatment approaches and the
availability of those who might deliver treatment should
be considered when planning clinical trials. In this
regard, patients with FMD may not accept that there is
an important psychological dimension to their symptoms, and therefore they might be less likely to accept
treatments based solely on psychotherapy or cognitivebehavioural therapy. However, research on symptomfocused cognitive-behavioural therapy approaches and
simple physical interventions point towards workable
interventions which, if given early in the course of the
illness, could produce benefit in these patients.
Education
None of the aforementioned suggested changes is likely
to happen unless concerted efforts are made to increase
interest and knowledge about FMD among movement
disorder specialists. Through this process, patients will
be most likely to receive early positive diagnoses, avoid
iatrogenic harm by unnecessary investigations and treatments, benefit from world-class research, and receive
effective treatment in a timely manner.
Conclusions
We have described here how the correct diagnosis of
FMD should rely on positive clinical characteristics and
not on the presence of psychological trauma. The
historical emphasis on psychological trauma as a
triggering factor has perhaps skewed research agendas
and neurological interest in these patients, and has
certainly alienated many patients who cannot believe
that their physical symptoms are related to psychological trauma. We do not aim to minimise the
importance of psychological factors (anxiety, depression,
arousal, and attention) in such patients, but rather to
258
point out that a dogmatic and relentless search for a
clear triggering psychological trauma may be misguided
and unhelpful.
One additional benefit of rebalancing the approach to
FMD and functional disorders in general is that it might
allow us to reconsider some of the symptoms that are
present in our patients with organic neurological disorders. Any practising neurologist would recognise that
patients with the same organic disease of apparently
similar severity manifest symptoms in differing ways,
which can have a dramatic effect on disability and quality
of life. This phenomenon, often called functional overlay,
is, we would suggest, often ignored as a non-symptom
that interferes with the neurological management of
patients. However, understanding the pathophysiology
of this overlay and knowing how to treat it—knowledge
that is likely to come from research into pure functional
disorders—could be of substantial benefit to patients
with organic disease. The common occurrence of
physical triggering events such as illness or injury in
patients with pure functional symptoms is itself a pointer
towards an important overlap between organic and nonorganic illness.5
Although we agree that FMD and other functional
disorders do represent a crisis for neurology, it is not
an unsolvable one. We believe that now is the time for
the movement disorder and wider neurological
community, in cooperation with psychiatry, psychology,
and physical therapy services, to lead the search for
solutions.
Contributors
MJE and KPB generated an outline for the paper. MJE wrote the first
draft and MJE and KPB revised this draft.
Conflicts of interest
MJE is supported by a National Institute for Health Research (NIHR)
Clinician Scientist Fellowship; has received funding from the UK
Dystonia Society and Parkinson’s UK; receives royalties from The
Oxford Specialist Handbook of Parkinson’s Disease and Other
Movement Disorders (Oxford University Press, 2008); and has received
honoraria for speaking engagements from the Movement Disorders
Society and UCB. KPB has received funding for travel from
GlaxoSmithKline, Orion Corporation, Ipsen, and Merz
Pharmaceuticals; serves on the editorial boards of Movement Disorders
and Therapeutic Advances in Neurological Disorders; receives royalties
from the publication of The Oxford Specialist Handbook of
Parkinson’s Disease and Other Movement Disorders (Oxford
University Press, 2008); received speaker honoraria from
GlaxoSmithKline, Ipsen, Merz Pharmaceuticals, and Sun
Pharmaceutical Industries; and has received research support from
Ipsen and the Halley Stewart Trust through the Dystonia Society UK
and the Wellcome Trust MRC strategic neurodegenerative disease
initiative award (reference number WT089698).
Acknowledgments
MJE is supported by an NIHR Clinician Scientist Grant. NIHR had no
involvement in the writing of the paper or in the decision to submit for
publication.
References
1
Stone J, Carson A, Duncan R, et al. Who is referred to neurology
clinics?—the diagnoses made in 3781 new patients.
Clin Neurol Neurosurg 2010; 112: 747–51.
2
Hallett M. Psychogenic movement disorders: a crisis for neurology.
Curr Neurol Neurosci Rep 2006; 6: 269–71.
www.thelancet.com/neurology Vol 11 March 2012
Review
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Espay AJ, Goldenhar LM, Voon V, et al. Opinions and clinical
practices related to diagnosing and managing patients with
psychogenic movement disorders: an international survey of
movement disorder society members. Mov Disord 2009;
24: 1366–74.
Kanaan R, Armstrong D, Barnes P, et al. In the psychiatrist’s chair:
how neurologists understand conversion disorder. Brain 2009;
132: 2889–96.
Stone J, Edwards MJ. How “psychogenic” are psychogenic
movement disorders? Mov Disord 2011; 26: 1787–88.
Marsden CD. Hysteria—a neurologist’s view. Psychol Med 1986;
16: 277–88.
Trimble MR. Functional diseases. BMJ 1982; 285: 1768–70.
Stone J, Wojcik W, Durrance D, et al. What should we say to
patients with symptoms unexplained by disease? The “number
needed to offend”. BMJ 2002; 325: 1449–50.
Factor SA, Podskalny GD, Molho ES. Psychogenic movement
disorders: frequency, clinical profile, and characteristics.
J Neurol Neurosurg Psychiatry 1995; 59: 406–12.
Williams DT, Ford B, Fahn S. Phenomenology and psychopathology
related to psychogenic movement disorders. Adv Neurol 1995;
65: 231–57.
Anderson KE, Gruber-Baldini AL, Vaughan CG, et al. Impact of
psychogenic movement disorders versus Parkinson’s on disability,
quality of life, and psychopathology. Mov Disord 2007; 22: 2204–09.
Carson A, Stone J, Hibberd C, et al. Disability, distress and
unemployment in neurology outpatients with symptoms
‘unexplained by organic disease’. J Neurol Neurosurg Psychiatry 2011;
82: 810–13.
Bermingham S, Hague J, Parsonage M. The cost of somatisation
among the working age population of England for the year
2008/2009. Mental Health in Family Medicine 2011; 7: 71–84.
Knapp M, Prince M, Albanese E, et al. Dementia UK: The Full
Report. London: Alzheimer’s Society, 2007.
Schwingenschuh P, Pont-Sunyer C, Surtees R, et al. Psychogenic
movement disorders in children: a report of 15 cases and a review of
the literature. Mov Disord 2008; 23: 1882–88.
Benbadis SR, Agrawal V, Tatum WO. How many patients with
psychogenic nonepileptic seizures also have epilepsy? Neurology
2001; 57: 915–17.
Ranawaya R, Riley D, Lang A. Psychogenic dyskinesias in patients
with organic movement disorders. Mov Disord 1990; 5: 127–33.
Onofrj M, Bonanni L, Manzoli L, et al. Cohort study on somatoform
disorders in Parkinson disease and dementia with Lewy bodies.
Neurology 2010; 74: 1598–606.
van Poppelen D, Saifee TA, Schwingenschuh P, et al. Attention to
self in psychogenic tremor. Mov Disord 2011; 26: 2575–76.
Kenney C, Diamond A, Mejia N, et al. Distinguishing psychogenic
and essential tremor. J Neurol Sci 2007; 263: 94–99.
Zeuner KE, Shoge RO, Goldstein SR, et al. Accelerometry to
distinguish psychogenic from essential or parkinsonian tremor.
Neurology 2003; 61: 548–50.
Kumru H, Begeman M, Tolosa E, et al. Dual task interference in
psychogenic tremor. Mov Disord 2007; 22: 2077–82.
Kumru H, Valls-Sole J, Valldeoriola F, et al. Transient arrest of
psychogenic tremor induced by contralateral ballistic movements.
Neurosci Lett 2004; 370: 135–39.
Deuschl G, Koster B, Lucking CH, et al. Diagnostic and
pathophysiological aspects of psychogenic tremors. Mov Disord
1998; 13: 294–302.
Schwingenschuh P, Katschnig P, Seiler S, et al. Moving toward
“laboratory-supported” criteria for psychogenic tremor. Mov Disord
2011; 26: 2509–15.
Edwards MJ. Dystonia: a clinical approach. Acta Neurol Taiwan
2008; 17: 219–27.
Bhatia KP, Bhatt MH, Marsden CD. The causalgia-dystonia
syndrome. Brain 1993; 116: 843–51.
van Hilten JJ, van de Beek WJ, Roep BO. Multifocal or generalized
tonic dystonia of complex regional pain syndrome: a distinct clinical
entity associated with HLA-DR13. Ann Neurol 2000; 48: 113–16.
Lang AE. Psychogenic dystonia: a review of 18 cases.
Can J Neurol Sci 1995; 22: 136–43.
www.thelancet.com/neurology Vol 11 March 2012
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
Schrag A, Trimble M, Quinn N, et al. The syndrome of fixed
dystonia: an evaluation of 103 patients. Brain 2004; 127: 2360–72.
Edwards MJ, Bhatia KP, Cordivari C. Immediate response to
botulinum toxin injections in patients with fixed dystonia.
Mov Disord 2011; 26: 917–18.
Avanzino L, Martino D, van de Warrenburg BP, et al. Cortical
excitability is abnormal in patients with the “fixed dystonia”
syndrome. Mov Disord 2008; 23: 646–52.
Quartarone A, Rizzo V, Terranova C, et al. Abnormal sensorimotor
plasticity in organic but not in psychogenic dystonia. Brain 2009;
132: 2871–77.
Katschnig P, Edwards MJ, Schwingenschuh P, et al. Mental rotation
of body parts and sensory temporal discrimination in fixed dystonia.
Mov Disord 2010; 25: 1061–67.
Edwards MJ, Alonso-Canovas A, Schrag A, et al. Limb amputations
in fixed dystonia: a form of body integrity identity disorder?
Mov Disord 2011; 26: 1410–14.
Brown P, Thompson PD. Electrophysiological aids to the diagnosis of
psychogenic jerks, spasms, and tremor. Mov Disord 2001; 16: 595–99.
Duggal HS, Nizamie SH. Bereitschaftspotential in tic disorders:
a preliminary observation. Neurol India 2002; 50: 487–89.
Obeso JA, Rothwell JC, Marsden CD. Simple tics in Gilles de la
Tourette’s syndrome are not prefaced by a normal premovement
EEG potential. J Neurol Neurosurg Psychiatry 1981; 44: 735–38.
Esposito M, Edwards MJ, Bhatia KP, et al. Idiopathic spinal
myoclonus: a clinical and neurophysiological assessment of a
movement disorder of uncertain origin. Mov Disord 2009; 24: 2344–49.
van der Salm SM, Koelman JH, Henneke S, et al. Axial jerks:
a clinical spectrum ranging from propriospinal to psychogenic
myoclonus. J Neurol 2010; 257: 1349–55.
Baik JS, Lang AE. Gait abnormalities in psychogenic movement
disorders. Mov Disord 2007; 22: 395–99.
Jordbru AA, Smedstad LM, Moen VP, Martinsen EW. Identifying
patterns of psychogenic gait by video-recording. J Rehabil Med
2012; 44: 31–35.
Keane JR. Hysterical gait disorders: 60 cases. Neurology 1989;
39: 586–89.
Lempert T, Brandt T, Dieterich M, et al. How to identify
psychogenic disorders of stance and gait. A video study in
37 patients. J Neurol 1991; 238: 140–46.
Stone J, Warlow C, Sharpe M. The symptom of functional weakness:
a controlled study of 107 patients. Brain 2010; 133: 1537–51.
Benaderette S, Zanotti FP, Apartis E, et al. Psychogenic
parkinsonism: a combination of clinical, electrophysiological, and
[(123)I]-FP-CIT SPECT scan explorations improves diagnostic
accuracy. Mov Disord 2006; 21: 310–17.
Gupta A, Lang AE. Psychogenic movement disorders.
Curr Opin Neurol 2009; 22: 430–36.
Fahn S, Williams DT. Psychogenic dystonia. Adv Neurol 1988;
50: 431–55.
Shill H, Gerber P. Evaluation of clinical diagnostic criteria for
psychogenic movement disorders. Mov Disord 2006; 21: 1163–68.
Voon V, Lang AE, Hallett M. Diagnosing psychogenic movement
disorders—which criteria should be used in clinical practice?
Nat Clin Pract Neurol 2007; 3: 134–35.
Morgante F, Edwards MJ, Espay AJ, et al. Diagnostic agreement
in patients with psychogenic movement disorders. Mov Disord
(in press).
Brown RJ. Psychological mechanisms of medically unexplained
symptoms: an integrative conceptual model. Psychol Bull 2004;
130: 793–812.
Kranick S, Ekanayake V, Martinez V, et al. Psychopathology and
psychogenic movement disorders. Mov Disord 2011; 26: 1844–50.
Haggard P. Human volition: towards a neuroscience of will.
Nat Rev Neurosci 2008; 9: 934–46.
Voon V, Gallea C, Hattori N, et al. The involuntary nature of
conversion disorder. Neurology 2010; 74: 223–28.
Edwards MJ, Moretto G, Schwingenschuh P, et al. Abnormal sense
of intention preceding voluntary movement in patients with
psychogenic tremor. Neuropsychologia 2011; 49: 2791–93.
Voon V, Brezing C, Gallea C, et al. Emotional stimuli and motor
conversion disorder. Brain 2010; 133: 1526–36.
259
Review
58
59
60
61
62
63
64
65
260
Voon V, Brezing C, Gallea C, et al. Aberrant supplementary motor
complex and limbic activity during motor preparation in motor
conversion disorder. Mov Disord 2011; 26: 2396–403.
Parees I, Saifee TA, Kassavetis P, et al. Believing is perceiving:
self-report and actigraphy mismatch in psychogenic tremor. Brain
2011; published online Nov 10. DOI:10.1093/brain/awr292.
Stamelou M, Edwards MJ, Espay AJ, et al. Movement disorders on
YouTube—caveat spectator. N Engl J Med 2011; 365: 1160–61.
Stone J. Functional and dissociative neurological symptoms:
a patient’s guide. http://www.neurosymptoms.org/ (accessed
Jan 27, 2012).
van Hilten BJ, van de Beek WJ, Hoff JI, et al. Intrathecal baclofen
for the treatment of dystonia in patients with reflex sympathetic
dystrophy. N Engl J Med 2000; 343: 625–30.
van Rijn MA, Munts AG, Marinus J, et al. Intrathecal baclofen for
dystonia of complex regional pain syndrome. Pain 2009; 143: 41–47.
Hinson VK, Weinstein S, Bernard B, et al. Single-blind clinical trial
of psychotherapy for treatment of psychogenic movement
disorders. Parkinsonism Relat Disord 2006; 12: 177–80.
Sharpe M, Walker J, Williams C, et al. Guided self-help for
functional (psychogenic) symptoms: a randomized controlled
efficacy trial. Neurology 2011; 77: 564–72.
66
67
68
69
70
71
72
Voon V, Lang AE. Antidepressant treatment outcomes of
psychogenic movement disorder. J Clin Psychiatry 2005; 66: 1529–34.
Czarnecki K, Thompson JM, Seime R, et al. Functional movement
disorders: successful treatment with a physical therapy
rehabilitation protocol. Parkinsonism Relat Disord 2011; published
online Nov 21. DOI:10.1016/j.parkreldis.2011.10.011.
Dallocchio C, Arbasino C, Klersy C, et al. The effects of physical
activity on psychogenic movement disorders. Mov Disord 2010;
25: 421–25.
Shamy MC. The treatment of psychogenic movement disorders
with suggestion is ethically justified. Mov Disord 2010; 25: 260–64.
Dafotakis M, Ameli M, Vitinius F, et al. Transcranial magnetic
stimulation for psychogenic tremor—a pilot study.
Fortschr Neurol Psychiatr 2011; 79: 226–33.
Jankovic J, Vuong KD, Thomas M. Psychogenic tremor: long-term
outcome. CNS Spectr 2006; 11: 501–08.
Thomas M, Vuong KD, Jankovic J. Long-term prognosis of patients
with psychogenic movement disorders. Parkinsonism Relat Disord
2006; 12: 382–87.
www.thelancet.com/neurology Vol 11 March 2012