Cranial functional (psychogenic) movement disorders Diego Kaski*, Adolfo M Bronstein, Mark J Edwards, Jon Stone* Lancet Neurol 2015; 14: 1196–205 *Contributed equally Department of Neuro-otology, National Hospital for Neurology and Neurosurgery, London, UK (D Kaski PhD, Prof A M Bronstein FRCP, M J Edwards PhD); Division of Brain Sciences, Imperial College London, Charing Cross Hospital, London, UK (D Kaski, Prof A M Bronstein); Sobell Department of Motor Neuroscience and Movement, UCL Institute of Neurology, London, UK (M J Edwards); and Department of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh, UK (J Stone FRCP) Correspondence to: Dr Diego Kaski, Department of Neuro-otology, National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK [email protected]
Functional (psychogenic) neurological symptoms are frequently encountered in neurological practice. Cranial movement disorders—aﬀecting the eyes, face, jaw, tongue, or palate—are an under-recognised feature of patients with functional symptoms. They can present in isolation or in the context of other functional symptoms; in particular, for functional eye movements, positive clinical signs such as convergence spasms can be triggered by the clinical examination. Although the specialty of functional neurological disorders has expanded, appreciation of cranial functional movement disorders is still insuﬃcient. Identiﬁcation of the positive features of cranial functional movement disorders such as convergence and unilateral platysmal spasm might lend diagnostic weight to a suspected functional neurological disorder. Understanding of the diﬀerential diagnosis, which is broad and includes many organic causes (eg, stroke), is essential to make an early and accurate diagnosis to prevent complications and initiate appropriate management. Increased understanding of these disorders is also crucial to drive clinical trials and studies of individually tailored therapies.
Introduction Cranial movement disorders aﬀect the eyes, face, jaw, tongue, or palate. These abnormalities are perhaps an under-recognised feature of patients with functional (psychogenic) neurological symptoms1–3 and, in our experience, a common concomitant of other functional neurological symptoms. Up to 6% of all patients with functional movement disorders present with abnormalities in facial movement,3 but the prevalence of functional eye movement disorders is largely unknown. Patients can present overtly with a complaint suggestive of an eye movement disorder (eg, double vision) or a facial symptom (eg, so-called drooping mouth) with or without additional neurological symptoms. More rarely, in a patient with functional neurological symptoms, functional eye movement abnormalities and, less commonly, facial abnormalities arise only on formal examination, which can cause diagnostic confusion. As with other motor disturbances such as weakness or tremor, such features are particularly amenable to objective clinical assessment (by contrast with subjective report of sensory symptoms) and therefore provide an excellent opportunity to make a positive and speciﬁc diagnosis of a functional movement disorder. The specialty of functional neurological disorders has expanded, with an increasing awareness that the diagnosis and treatment of these disorders are a neurologist’s responsibility. Nevertheless, cranial functional movement disorders are still neglected in the medical literature.1 Failure to correctly classify and diagnose functional disorders can lead to serious iatrogenic damage and deny the patient the appropriate treatment. Patients are often sent from one specialist to another, with a range of symptoms that remain unexplained by several laboratory or radiological investigations. A positive diagnosis of a functional disorder can break this cycle and lead to physical or psychological rehabilitation. Moreover, accurate diagnosis has particular implications for the diagnosis of acute stroke, in which inappropriate treatment with thrombolysis can have detrimental eﬀects. Finally, the scarcity of treatment studies for cranial
functional movement disorders underpins the need for an increased awareness and improved knowledge of these disorders, in view of the potential for phenotype-speciﬁc treatment outcomes.1 In this Review, we highlight the facial and ocular symptoms that can have a functional origin, review the common symptoms and positive clinical signs of cranial functional movement disorders, and contrast these with some key signs of organic pathology to help with diagnosis and a rational approach to management. We discuss all cranial functional movement disorders that we have encountered in general neurology and specialist movement disorder clinical practice. Finally, we discuss the present state of the discipline and suggest directions for future research. Although we recognise the advantages and disadvantages of the terms “functional” and “psychogenic”,4,5 we will refer to these disorders as functional in this Review.
Functional eye movement disorders Convergence spasm Convergence is a normal eye movement reﬂex occurring when gaze is shifted from a distant object to a near object. Convergence spasm (also known as spasm of the near reﬂex) refers to the abnormal persistence of this movement when the patient is not ﬁxating on a near object (ﬁgure 1). It is the most frequently reported functional eye movement disorder and was noted in nine of 13 patients in a small study of people with functional movement disorders.2 Patients with convergence spasm might complain of blurry vision when looking at a distance following near ﬁxation (eg, reading). Other symptoms include intermittent diplopia and intermittent blurred vision that typically is corrected by squeezing the eyelids shut tightly and opening them again. Symptoms usually last for seconds but can be described as continuous when one episode of spasm is succeeded by another. Convergence spasm is shown when the patient is asked to look at a near object (30–40 cm), which could be the doctor. It is often triggered by formal ocular examination whereby the patient’s angle of convergence becomes clearly too large for the visual target oﬀered and the www.thelancet.com/neurology Vol 14 December 2015
pupils become excessively miotic. On moving the target further away or on asking the patient to look at a distant object (eg, the wall behind the examiner), the convergence and miosis persist. If the ﬁxation target is then moved to lateral gaze, the excessive convergence also continues, and one or both eyes remain adducted with strong medial rectus contraction (videos 1, 2). As a result, patients with convergence spasm are often misdiagnosed as having unilateral or bilateral abducens nerve palsies.6 Formal oculographic recordings can help with the diagnosis. Convergence spasm can be diﬀerentiated from an abducens palsy7 by the presence of miosis; a full range of movements shown by rapid, small-amplitude passive head turns (head impulse test8), optokinetic stimuli, or dolls-eye manoeuvre; the absence of other oculomotor signs, such as gaze paretic nystagmus (nystagmus that occurs in the adducting [normal] eye); and the appearance of the convergence spasm only during formal assessment but not during casual examination while history taking. Organic causes of convergence spasm are rare and include disease at the diencephalic–mesencephalic junction (thalamic esotropia), Wernicke-Korsakoﬀ syndrome, posterior fossa lesions, epilepsy, and phenytoin toxicity.7 However, in many of these reported cases, the description of the symptoms and signs actually suggests convergence spasm that is comorbid with the underlying organic problem or, in the case of Wernicke-Korsakoﬀ syndrome, perhaps with bilateral abducens nerve palsies. Finally, convergence spasm has been reported in patients with benign paroxysmal positional vertigo during provocation (positional) manoeuvres,9,10 and has also been reported to mimic benign paroxysmal positional vertigo10—ﬁndings that we have also noted clinically. A case of spontaneous convergence spasm (unrelated to positional manoeuvres) has also been reported in the context of a peripheral vestibulopathy.11 Such cases might relate to a voluntary attempt to suppress the nystagmus (and thus reduce symptoms), or might be a functional response to disabling vertigo. Caution is needed to avoid overinterpretation of mild convergence spasm. For example, convergence spasm was found not only in four of 11 patients with an organic movement disorder but also in four of 12 healthy controls.2 This ﬁnding is surprising in view of the rare occurrence of convergence spasm in healthy individuals in neuro-otology and eye movement clinics in our experience. Of note, convergence and divergence are under voluntary and reﬂex oculomotor control, and are thus the only dysconjugate ocular movement that can be initiated voluntarily.
Convergence paralysis Convergence paralysis (also known as convergence insuﬃciency) describes a partial or complete failure of convergence. Diplopia exists only at near ﬁxation, adduction is normal, and the patient is unable to converge.12 Accommodation can be normal, reduced, or www.thelancet.com/neurology Vol 14 December 2015
Figure 1: Convergence spasm in two women aged 28 years (A, B) and 24 years (C, D) (A) Excessive and prolonged convergence in the right eye on attempted downward gaze. (B) She is able to fully abduct the right eye, ruling out abducens nerve palsy. (C) Left-sided convergence spasm on downward gaze. (D) Full abduction in the left eye, with miosis. See video 1.
absent. Patients often report diﬃculty reading, particularly at close range, and blurring of vision. Diﬀerentiation of organic from functional convergence paralysis is a greater clinical challenge than diagnosis of convergence spasm, because it represents an absence of movement rather than the generation of a complex oculomotor action. In organic convergence paralysis, as in normal ageing or neurodegeneration,13 convergence will always be absent. In functional convergence paralysis, convergence movements might be seen during casual examination when the patient is doing other near-vision tasks, such as looking at their own wristwatch,14 or by asking the patient to read out his or her prescriptions. Another practical method to induce convergence in patients with suspected functional convergence paralysis is by asking the patient to follow a visual target (eg, the examiner’s ﬁnger) from side to side, while subtly and slowly moving the target closer to the patient’s nose.
See Online for video
Gaze limitation Functional gaze limitation most often manifests on formal testing of eye movements rather than presenting as a primary complaint. Patients may have eyelid ﬂuttering on attempted eye movements and eﬀortful facial movements or facial grimacing15 exclusively during examination (videos 3, 4). Many patients also report pain when making eye movements, especially during upwardgaze testing in those with a headache, with a tendency to avoid moving the eyes on formal examination, but no apparent discomfort during casually observed saccades. Patients may be unable to move their eyes in vertical16 or horizontal directions17 when they are asked to follow a visual target, but show full ocular excursions in response to optokinetic stimuli or during passive head rotations. They may also complain of diplopia despite conjugate eye movements (ie, a normal alignment of both eyes). 1197
Functional gaze limitation can accompany symptoms such as poor mobility and globally slow movements that might suggest parkinsonism.18 It can be distinguished from organic supranuclear palsies by the presence of normal saccades during casual examination and the presence of variability. Most organic causes of supranuclear gaze palsy are accompanied by slow saccades, which are not seen in functional disorders. Furthermore, the diagnosis of functional vertical gaze palsy can usually be supported by the ﬁnding that the eyebrows do not elevate during attempted upward gaze (whereas the eyebrows do elevate in organic vertical gaze palsy).16
Functional and voluntary nystagmus and oscillopsia The term voluntary nystagmus has been used to describe a high-frequency, horizontal, low-amplitude eye oscillation that can be voluntarily initiated and terminated.19 Functional nystagmus refers to the same event when it arises as an involuntary symptom with oscillopsia (wobbly, unstable, or blurred vision in which the images are jumping). A survey by Zahn20 showed that about 8% of college students (aged 18–24 years) can produce voluntary nystagmus at will. A
B Functional nystagmus
The eye oscillations of voluntary nystagmus (ﬁgure 2A; videos 5, 6) are conjugate and of high frequency. The term nystagmus is in fact incorrect because, in voluntary and functional nystagmus, the slow-phase eye movement that characterises actual nystagmus (ﬁgure 2B) is absent. Voluntary nystagmus is conﬁned to horizontal oscillations, which can be superimposed on smooth pursuit movements and can also be accompanied by a head tremor and eyelid ﬂutter.21 Typically, voluntary nystagmus cannot be maintained for more than 25 s20 (although it is usually much briefer and lasts around 2–5 s in our experience; video 5), and the nystagmus tends to decrease in amplitude and duration during this period. By contrast, ocular ﬂutter, the main diﬀerential diagnosis, is persistent and is usually associated with cerebellar or brainstem oculomotor or pyramidal signs.22 Patients with functional nystagmus might present with oscillopsia (panel 1). Similar to many of the functional disorders of the eyes and face, functional nystagmus can be triggered by the examination, especially of eye movements, but might not be present during casual examination. Convergence might be seen at the onset of the nystagmus (video 6), sometimes amounting to full convergence spasm, and diminution in the intensity and frequency of the nystagmus is also seen with repeated examination. Although the combination of intermittent oscillopsia and diplopia can suggest a combination of convergence spasm and functional nystagmus, alternative explanations for this symptom complex exist (table 1); thus, a careful examination should always be done.
A note on diplopia No slow phase
Figure 2: Eye movements of functional and organic nystagmus (A) Binocular horizontal electronystagmogram trace recorded from a patient with functional (voluntary) nystagmus during convergence. Note the brief high-frequency oscillations seen during convergence lasting 1·5 s. (B) Illustrative example of horizontal jerk nystagmus with a slow phase to the right (upward deﬂection) and a fast phase to the left (downward deﬂection). See video 5.
Panel 1: Functional nystagmus A man aged 17 years was preparing for his college examinations. Towards the end of the day, having been reading for several hours, he developed brief, rapid oscillation of the eyes leading to oscillopsia. The following day, fearing a neurological disease, he saw his general practitioner, who referred him to a neurologist. No diagnosis was made, but the patient was referred for an MRI brain scan, in which no abnormalities were noted. Although reassured by the doctor, the patient continued to have oscillopsia, restricting his ability to function. The symptoms settled when he received an explanation of the nature of the nystagmus.
Diplopia can be a symptom of a functional eye movement disorder. Organic diplopia is typically binocular (ie, disappears when one eye is covered) and is the result of dysconjugate gaze (ie, failure of the eyes to turn together in the same direction). Thus, movement of one or more ocular muscles will be restricted, which can be conﬁrmed clinically or with a Hess chart. Asking the patient to look in the direction of the suspected weak muscle will increase the diplopia (eg, left lateral gaze for a left lateral rectus weakness) in organic diplopia. Monocular diplopia can sometimes be caused by ocular pathology (eg, retinal disease, refractive errors, or abnormalities of the cornea and lens) and, more rarely, visual cortex lesions.24 In the presence of an organic cause, one image is clear and the other is blurred.25 Patients with functional monocular diplopia will often be unable to identify whether one image is blurred. Thus, true monocular diplopia, in which two separate and equal images of an object are seen with one eye only, almost always suggests a functional disorder. Triplopia and polyopia can also be functional, although in a review of 13 cases of triplopia, 11 had an organic diagnosis.26 www.thelancet.com/neurology Vol 14 December 2015
Distinguishing features from functional nystagmus
Episodes of oscillopsia lasting 3–20 s
Binocular conjugate high-frequency (5–28 Hz20) Functional oscillations without a slow phase. Triggered by examination. Convergence at onset with diplopia is common
Superior oblique myokymia
Brief (seconds) uniocular episodes of oscillopsia and imbalance, occurring several times per day
High-frequency (5–10 Hz23) spasmodic contractions of the superior oblique muscle (torsional [rotatory] ocular oscillation with intorsion)
Possible neurovascular compression of IV nerve at root entry zone
Uniocular. Diﬃcult to elicit during a clinic consultation because of paroxysmal nature
Brief (milliseconds to seconds) attacks of vestibular and auditory deﬁcits, including vertigo, imbalance, and tinnitus
Brief nystagmus in any plane is possible
Possible neurovascular compression of VII nerve
Rare to see nystagmus because of brevity of attacks and paroxysmal nature
Brief paroxysmal episodes of visual blurring and oscillopsia
Intermittent bursts of rapid (10–15 Hz), conjugate, horizontal saccades without an intersaccadic interval
Cerebellar or brainstem pathological changes
Persistent bursts of abnormal eye oscillation. Associated pyramidal, brainstem, or cerebellar signs. Persists during eyelid closure
Continuous (or almost continuous) Rapid, chaotic, conjugate saccadic movements oscillopsia of the eyes in horizontal, vertical, and torsional planes
Neuroblastoma or paraneoplastic syndromes
Persist during eyelid closure and sleep
Table 1: Causes of oscillopsia and clinical features that help to distinguish functional nystagmus from other causes
Functional upper facial movement disorders The most common type of functional movement disorder in the ocular region of the face is eye closure, which typically presents with episodic and unilateral contraction of the orbicularis oculis3 (ﬁgure 3), although such contraction can also be bilateral (video 11). The orbicularis contraction can appear jerky, and the muscular oscillations can sometimes be felt by gently placing a ﬁnger over the aﬀected eyelid. Eye closure can be mistaken for ptosis, and so the term pseudoptosis has sometimes been used to describe this situation. However, the use of such a term is misleading, since eye closure is usually related to a contraction of the orbicularis muscle around the eye rather than failure of the levator palpabrae,27 although we have seen the latter on a few occasions. Alternatively, overcontraction of the orbicularis oculis can mimic a unilateral weakness of the frontalis, with an apparent inability to elevate the eyebrow on the aﬀected side, or with an eyebrow that is depressed relative to the normal side (ﬁgure 4). When the patient attempts to elevate the eyebrow or look up, this action might increase contraction of the orbicularis oculis in a functional facial movement disorder. In organic hemifacial spasm, elevation of the eyebrow is sometimes seen on the same side as the eye closure, as a result of co-contraction of the orbicularis oculi and the internal part of the frontalis (ﬁgure 4B). This is sometimes called the other Babinski sign28,29 and helps to diﬀerentiate organic hemifacial spasm from functional orbicularis oculis contraction, in which spontaneous overactivity of the contralateral frontalis is sometimes reported (ﬁgure 4C).3 This sign has never been reported in blepharospasm, a focal dystonia characterised by forceful, involuntary, spasmodic contraction of the orbicularis oculi (ﬁgure 4A). Neurophysiological studies assessing the blink reﬂex are also helpful to disambiguate between essential and presumed functional blepharospasm.30 In www.thelancet.com/neurology Vol 14 December 2015
organic blepharospasm, the blink reﬂex recovery cycle is disrupted as a result of abnormal brainstem interneuron excitability, whereas in functional eye closure the blink reﬂex is normal. Resolution of symptoms during speciﬁc tasks will assist with diagnosis; one patient seen in our clinic had bilateral complete eye closure that resolved when he was playing video games.
Functional movement disorders of the mouth, tongue, and palate Several distinctive features point towards a functional movement disorder of the mouth, tongue, or palate. Functional hemifacial spasm is seen in 2–6% of patients referred for specialist assessment of hemifacial abnormal movements,31 although more data are needed to establish the true frequency. In a landmark case series by Fasano and colleagues,3 56 (92%) of 61 patients were female, and the mean age of the patients was 37 years. The platysma is commonly contracted, which leads to the corner of the mouth being pulled down on one side, giving an appearance of weakness (ﬁgure 3; video 7). Less frequently, the corner of the mouth might be elevated compared with the other side (videos 8, 11). Jaw deviation to the aﬀected side is a common and speciﬁc sign in many patients with functional facial spasm (video 10), and evidence of a functional motor and sensory disorder in the ipsilateral arm and leg is often seen in these patients.2 Of note, more than one neurological lesion is usually needed for the presence of motor symptoms in the upper and lower halves of the face and the ipsilateral arm and leg to have an anatomical basis—a fact that might be useful to help both patients and non-neurologists to understand the rationale for a functional diagnosis. The combination of platysmal spasm, leading to the appearance of mouth drooping, and hemiparesis understandably can lead to concerns about acute stroke, especially if the FAST (face, 1199
Figure 3: Functional facial movement disorders (A) Left-sided platysma contraction with jaw deviation, accompanied by a functional left hemiparesis (see video 7). (B) Contraction of the orbicularis oculis. (C) Episodic bilateral facial spasm induced by testing eye movements (see video 8): normal appearance (ﬁrst image); sequential ptosis (second image); platysma contraction (third image); and bilateral platysma and orbicularis oculis contraction (fourth image). (D) Right facial spasm induced by light: normal appearance (ﬁrst image); appearance at rest after light stimulation (second image); attempting to raise both eyebrows (third image; see video 9). (E) Right platysma contraction with jaw deviation, giving the appearance of a drooping mouth (see video 10). (F) Persistent right unilateral facial spasm associated with jaw and tongue deviation. (G) Episodic right eye and face contraction with upward movement of the mouth associated with hyperventilation (see video 11).
arm, leg, time) test for acute stroke (ﬁgure 3) is applied uncritically. Functional disorders account for around 10% of stroke mimics in published series.32 Functional movement disorders aﬀecting the tongue typically coexist with functional hemifacial spasm. In functional hemilingual spasm, the tongue usually deviates towards the side of a facial spasm (ie, the spasm is all on the same side; ﬁgure 5). In organic hypoglossal palsy, if the lesion is supranuclear (eg, following a stroke), only the lower half of the face should be weak, and the tongue would also deviate towards the same side as the aﬀected part of the face (and away from the lesion; ﬁgure 5).33 If the lesion is in the pons or medulla, then the ipsilateral face (including the eye) might be weak (from seventh nerve involvement) and the tongue would deviate 1200
towards the lesion, towards the aﬀected half of the face but away from the side of limb weakness (ﬁgure 5). The diﬀerential diagnosis of facial hyperkinetic movement disorder34 is wide, and familiarity with these entities is needed to make an accurate diagnosis (table 2). Most of these diﬀerential diagnoses involve brief movements in facial muscles rather than the sustained contractions typically seen in patients with a functional disorder. Palatal tremor (often termed palatal myoclonus) can also occur as a functional movement disorder.35,36 In a retrospective description of 17 patients with isolated palatal tremor, ten were deemed to have functional palatal tremor on the basis that the tremor was variable (spontaneous changes in frequency, amplitude, direction, or characteristics), entrainable (brought into a speciﬁc www.thelancet.com/neurology Vol 14 December 2015
rhythm or frequency by asking the patient to copy a motor activity of a given frequency), and distractible (a change in tremor amplitude, direction, or quality, with a decrease or cessation of tremor, when volitionally doing other cognitive or motor tasks).37 For example, palatal tremor transiently stopped when patients were asked to tap, with their ﬁngers, to a rhythm set by the examiner or to do ballistic reaching movements with the arms.38 Such patients are mostly female and younger than patients with organic palatal tremor (mean age at onset 35 years vs 54 years),37 and they frequently have a physical precipitating event such as a sore throat. These patients are more likely to have functional rocking movements of the head or neck, functional facial spasms, or functional visual disturbance. In our experience, ear clicking is particularly common in people with functional palatal tremor. Organic palatal tremor might be associated with pendular nystagmus, myoclonus, and cerebellar signs, and an abnormality of the inferior olive might be present on MRI brain scans.38,39
Generalised facial hyperkinetic or hypokinetic disorders Tics can sometimes be part of a functional movement disorder and often aﬀect the face and eyes. In a series of nine patients with functional or psychogenic tics,40 eight had hyperkinetic facial movements. The authors suggested several clinical features that can help to diﬀerentiate functional from organic tics:40 patients with functional tics tend to have an older age of onset (mean age 30 years, as opposed to childhood onset for most patients with Tourette’s syndrome), absence of premonitory sensation, an inability to transiently suppress the movements, no family history of Tourette’s syndrome,41 no response to dopamine receptor antagonists, and the coexistence of an associated functional movement disorder elsewhere in the body, such as limb tremor or weakness, or non-epileptic seizures.42 Just as limitation of eye movements can occur as a functional movement disorder, some patients present with weakness or inability to move facial muscles, which might be accompanied by an inability to speak (aphonia). In our experience, such patients have hypofunctioning of the vocal cords, whereby the cords approximate but remain open during attempted phonation43 (but patients have a normal cough). Patients in this situation are sometimes thought to have facial hypomimia, as seen in Parkinson’s disease and other parkinsonian disorders.18 Such apparent muscle weakness or slowness is typically variable and distractible, particularly during history taking.
Common features of examination ﬁndings Many paroxysmal functional movement disorders (particularly of the eyes) are present during consultation, whereas organic paroxysmal eye movement disorders (such as superior oblique myokymia or vestibular paroxysmia) are usually diﬃcult to trigger in the clinic (table 1). In a cranial functional movement disorder, the www.thelancet.com/neurology Vol 14 December 2015
Hemifacial spasm Eyebrow elevated on side of eye closure
Functional eye closure Eyebrow typically depressed on same side as eye closure and sometimes elevated on opposite side
Figure 4: Positions of eyelid and eyebrow in diﬀerent types of facial spasm (A) Blepharospasm: bilateral eyelid closure (can also be asymmetrical). Bilateral raising of eyebrows on attempted eye opening might be present. (B) The so-called other Babinski sign: paradoxical raising of the eyebrow on the same side (arrow) as the eye closure in a patient with organic hemifacial spasm. (C) Functional eye closure with eyebrow depressed on the side of eye closure (downward arrow) and sometimes elevated on the opposite side (upward arrow).
movements may be induced by sustained contraction of facial or ocular muscles (eg, for longer than 10 s).3 Since voluntary facial movements might also exacerbate synkinetic movements seen after facial palsy and sometimes in hemifacial spasm, sustained orbicularis oculis or platysma contraction is the key ﬁnding to diagnose a functional movement disorder. In some patients, examination of eye movements (video 8) or a light stimulus (using a pen torch) might trigger the abnormal movements, which more clearly suggest a functional disorder (ﬁgure 3; panel 2; video 9).
Pathophysiology The individual vulnerability to speciﬁc cranial functional movement disorders and the selective expression of these disorders (ie, why it can aﬀect the eyes in one patient and the tongue in another) are largely unanswered questions that might have important therapeutic implications. Although the pathophysiology of cranial functional movement disorders is probably no diﬀerent from other functional movement disorders, one reason that patients might manifest a cranial functional movement disorder over, for example, a functional limb tremor could be the coexistence of an organic pathological change in the face or eyes, prior injury to these areas, or an increased focus of attention on these areas by family members or doctors (eg, functional nystagmus; panel 1). Thus, enquiry about associated physical events and symptoms, including dental work, migraine, and injury to the face, might help to explain why the symptom began in the face and not somewhere else.44 On a related note, the presence of a functional disorder should always be a sign to the clinician that an additional disease process might have triggered the abnormality and might need to be identiﬁed.45 Neuroimaging ﬁndings in patients with functional movement disorders have shown alterations in brain circuits mediating, among other abilities, awareness (eg, the anterior cingulate cortex, insula, and amygdala) and self-referential processing (eg, the posterior parietal cortex 1201
and temporoparietal junction).46 Indeed, neurophysiology and neuroimaging oﬀer potential insights into the mechanism of functional movement disorders,47–49 but apart from the blink reﬂex cycle30 these have not yet been speciﬁcally applied to cranial functional movement disorders.
Treatment options General concepts Treatment options for cranial functional movement disorders are based on case series, case reports, and expert consensus rather than randomised controlled trials, although much improved treatment evidence is now emerging for functional motor disorders50–53 and non-epileptic seizures.54–56 Treatment begins with a positive clinical diagnosis and a clear explanation of the nature of the problem, including giving a diagnostic label to the patient.57 Motor signs can form an important part of the explanation of the diagnosis to patients—eg, through the use of pictures, videos, or eye movement recordings to explain how restriction of gaze during eye movement examination disappears when a patient is distracted.58 This feature also emphasises the potential for reversibility and that the disorder is a so-called software, not hardware, problem. This process of rational persuasion can set the scene for a therapeutic discussion about functional disorders: that they are common, genuine, but diﬀerent from organic neurological disease, and potentially reversible and that they have positive clinical signs that have enabled the diagnosis to be made. This step alone can produce major therapeutic beneﬁt and might, in some patients, be the only treatment necessary, perhaps by altering fundamental beliefs that are driving abnormally focused attention towards the symptom.59 This step is not about providing reassurance that there is nothing wrong, but rather about providing an explanation of what is wrong that reduces abnormal self-focused attention. For example, in our clinical experience we have A
Organic supranuclear cause of tongue weakness (eg, cortical stroke)
sometimes encountered teenagers with brief paroxysmal oscillopsia (functional nystagmus) in the context of tired eyes, lack of sleep, and anxiety when revising for university admission exams. Anxiety from parents and doctors, and unnecessary (normal) investigations tend to increase the frequency of the attacks. However, the attacks can be reduced or aborted with a convincing explanation and thus a reduced focus on the problem (panel 1). Little evidence supports the use of drug therapy to treat functional movement disorders at present, although medical treatment of associated neurological problems (eg, migraine, anxiety, or depression) is sometimes needed. Our clinical experience is that the prognosis for patients with functional eye and facial movement disorders is generally good (although not universally so), where facilities exist to provide patients with a thorough explanation of the cause of the symptoms and engage in therapy with appropriate follow-up.50,51 Improved epidemiological studies are needed to help to understand the scale of cranial functional movement disorders, and improved diagnostic accuracy and better use of digital technology will allow patients to capture intermittent eye movement problems, which could potentially be used as a form of biofeedback for treatment.
Functional eye movement disorders For functional eye movement disorders, our experience suggests that symptomatic improvement is helped by explanation that the problem is genuine or visible and relates to overactivity or underactivity in oculomotor pathways, that those pathways are not damaged, and that eye movements can be normalised through retraining. This approach can inform discussions about whether further investigations are needed and provide a logical basis for treatment, especially interventions designed to retrain the nervous system. Thus, exercises from an optometrist (eg, asking patients with functional limitation of gaze to make eye movements between targets that are
Left hypoglossal nucleus lesion (eg, pontomedullary lesion)
Functional hemilingual spasm
Figure 5: Hemilingual spasm (A) In organic supranuclear hypoglossal palsy, the tongue deviates towards a lower facial weakness and limb weakness. (B) With a pontomedullary lesion, the tongue deviates towards upper and lower facial weakness but away from the limb weakness. Ipsilesional wasting of the tongue might be seen. (C) In functional hemilingual spasm, the tongue also deviates towards the side of the functional facial spasm. If functional limb weakness is present, it is usually on the same side as the facial spasm. Star=site of lesion (no lesion for functional spasm).
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Presenting symptoms and common examination ﬁndings
Distinguishing features from functional facial spasm
Functional facial spasm
Typically unilateral sustained contraction of the orbicularis oculis Functional and oris, or the platysma, or both, that can occur in episodes. Jaw deviation to the aﬀected side. Eyebrow depressed on the aﬀected side. Additional convergence spasm or ipsilateral functional limb weakness, or both, is often present
Idiopathic hemifacial spasm
Synchronous unsustained unilateral contraction of facial muscles
The frontalis elevates if the orbicularis contracts (ie, raised eyebrow instead of depressed eyebrow). EMG shows myoclonic bursts of