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Functional dystonia in the foot and ankle
Abstract
Aims
To assess the characteristic clinical features, management, and outcome of patients who present to orthopaedic surgeons with functional dystonia affecting the foot and ankle.
Methods
We carried out a retrospective search of our records from 2000 to 2019 of patients seen in our adult tertiary referral foot and ankle unit with a diagnosis of functional dystonia.
Results
A total of 29 patients were seen. A majority were female (n = 25) and the mean age of onset of symptoms was 35.3 years (13 to 71). The mean delay between onset and diagnosis was 7.1 years (0.5 to 25.0). Onset was acute in 25 patients and insidious in four. Of the 29 patients, 26 had a fixed dystonia and three had a spasmodic dystonia. Pain was a major symptom in all patients, with a coexisting diagnosis of chronic regional pain syndrome (CRPS) made in nine patients. Of 20 patients treated with Botox, only one had a good response. None of the 12 patients who underwent a surgical intervention at our unit or elsewhere reported a subjective overall improvement. After a mean follow-up of 3.2 years (1 to 12), four patients had improved, 17 had remained the same, and eight reported a deterioration in their condition.
Conclusion
Patients with functional dystonia typically presented with a rapid onset of fixed deformity after a minor injury/event and pain out of proportion to the deformity. Referral to a neurologist to rule out neurological pathology is advocated, and further management should be carried out in a movement disorder clinic. Response to treatment (including Botulinum toxin (Botox) injections) is generally poor. Surgery in this group of patients is not recommended and may worsen the condition. The overall prognosis remains poor. Cite this article: Bone Joint J 2021;103-B(6):1127–1132.
Background:
Complex regional pain syndrome (CRPS) is a relatively common complication, occurring in 5% of cases after injury or surgery, particularly in the limbs. The incidence of CPRS is around 5- 26/100 000. The latest revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-11) now categorizes CRPS as a primary pain condition of multifactorial origin, rather than a disease of the skeletal system or the autonomic nervous system.
Methods:
Based on a selective search of the literature, we summarize current principles for the diagnosis and treatment of CRPS.
Results:
Regional findings in CRPS are accompanied by systemic symptoms, especially by neurocognitive disorders of body perception and of symptom processing. The therapeutic focus is shifting from predominantly passive peripheral measures to early active treatments acting both centrally and peripherally. The treatment is centered on physiotherapy and occupational therapy to improve sensory perception, strength, (fine) motor skills, and sensorimotor integration/ body perception. This is supported by stepped psychological interventions to reduce anxiety and avoidance behavior, medication to decrease inflammation and pain, passive physical measures for reduction of edema and of pain, and medical aids to improve functioning in daily life. Interventional procedures should be limited to exceptional cases and only be performed in specialized centers. Spinal cord and dorsal root ganglion stimulation, respectively, are the interventions with the best evidence.
Conclusion:
The modern principles for the diagnosis and treatment of CRPS consider both, physiological and psychological mechanisms, with the primary goal of restoring function and participation. More research is needed to strengthen the evidence base in this field.
Functional dystonia represents a condition where psychological distress is being expressed as involuntary muscle contractions. In the foot and ankle, it most commonly presents as a sudden onset of a painful fixed ankle/hindfoot deformity in a female patient with a history of trivial trauma or surgery. The “fixed deformity” found on clinical examination is usually correctable under general anesthesia. Less commonly, it can present in the toes or may present as paroxysmal muscle movements rather than a fixed deformity. CRPS may occur concurrently with the dystonia.
Failure to consider the diagnosis leads to a long delay in appropriate diagnosis, patient distress and unnecessary or even harmful surgery. A better approach to this clinical syndrome is to define it as fixed abnormal posturing that is most commonly psychogenic. Early referral to a movement disorder clinic is recommended. The prognosis is generally poor as less than a quarter of patients report subjective long-term improvement even when managed in a movement disorder clinic. Foot and ankle surgeons should, whenever possible, avoid operating on patients with functional dystonia in order to avoid symptomatic deterioration.
Importance
Functional neurological disorders (FND) are common sources of disability in medicine. Patients have often been misdiagnosed, correctly diagnosed after lengthy delays, and/or subjected to poorly delivered diagnoses that prevent diagnostic understanding and lead to inappropriate treatments, iatrogenic harm, unnecessary and costly evaluations, and poor outcomes.
Observations
Functional Neurological Symptom Disorder/Conversion Disorder was adopted by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, replacing the term psychogenic with functional and removing the criterion of psychological stress as a prerequisite for FND. A diagnosis can now be made in an inclusionary manner by identifying neurological signs that are specific to FNDs without reliance on presence or absence of psychological stressors or suggestive historical clues. The new model highlights a wider range of past sensitizing events, such as physical trauma, medical illness, or physiological/psychophysiological events. In this model, strong ideas and expectations about these events correlate with abnormal predictions of sensory data and body-focused attention. Neurobiological abnormalities include hypoactivation of the supplementary motor area and relative disconnection with areas that select or inhibit movements and are associated with a sense of agency. Promising evidence has accumulated for the benefit of specific physical rehabilitation and psychological interventions alone or in combination, but clinical trial evidence remains limited.
Conclusions and Relevance
Functional neurological disorders are a neglected but potentially reversible source of disability. Further research is needed to determine the dose and duration of various interventions, the value of combination treatments and multidisciplinary therapy, and the therapeutic modality best suited for each patient.
Clinical signs are critical in ascertaining the functional nature of a gait disorder. Four signs of gait impairment have been documented in the course of examining patients with clinically definite functional (psychogenic) movement disorders: “huffing and puffing” during standing and walking, manipulation-resistance dorsiflexion of the first toe, fixed plantar flexion and inversion, and marked discrepancy between ambulation with and without swivel chair assistance. While large studies are needed to ascertain their prevalence, sensitivity, and specificity, the identification of these signs may help elevate the diagnostic certainty of functional gait disorders.
Electronic supplementary material
The online version of this article (doi:10.1186/s40734-016-0031-1) contains supplementary material, which is available to authorized users.
This review explores recent developments in understanding the neurobiological mechanism of functional (psychogenic) movement disorders (FMDs). This is particularly relevant given the resurgence of academic and clinical interest in patients with functional neurological symptoms and the clear shift in diagnostic and treatment approaches away from a pure psychological model of functional symptoms.
Recent research findings implicate three key processes in the neurobiology of FMD (and by extension other functional neurological symptoms): abnormal attentional focus, abnormal beliefs and expectations, and abnormalities in sense of agency. These three processes have been combined in recent neurobiological models of FMD in which abnormal predictions related to movement are triggered by self-focused attention, and the resulting movement is generated without the normal sense of agency that accompanies voluntary movement.
New understanding of the neurobiology of FMD forms an important part of reappraising the way that patients with FMD (and other functional disorders) are characterized and treated. It also provides a testable framework for further exploring the pathophysiology of these common causes of ill health.
Opinion statement:
Dystonia is characterized by repetitive twisting movements or abnormal postures due to involuntary muscle activity. When limited to a single body region it is called focal dystonia. Examples of focal dystonia include cervical dystonia (neck), blepharospasm (eyes), oromandibular dystonia, focal limb dystonia, and spasmodic dysphonia, which are discussed here. Once the diagnosis is established, the therapeutic plan is discussed with the patients. They are informed that there is no cure for dystonia and treatment is symptomatic. The main therapeutic option for treating focal dystonias is botulinum toxin (BoNT). There have been several attempts to characterize the procedure, the type of toxin, dosage, techniques, and combination with physical measures in each of the focal dystonia forms. The general treatment principles are similar. The affected muscles are injected at muscle sites based on evidence and experience using standard dosages based on the type of toxin used. The injections are repeated after 3 to 6 months based on the individual response duration. In the uncommon event of nonresponse with BoNT, the dose and site are reassessed. Oral drug treatment could be considered as an additional option. Once the condition is thought to be medically refractory, the opinion from the deep brain stimulation (DBS) team for the suitability of the patient for DBS is taken. The successful use of DBS in cervical dystonia has led to increased acceptance for trial in other forms of focal dystonias. DBS surgery in focal dystonias other than cervical is, however, still experimental. The patients may be offered the surgery with adequate explanation of the risks and benefits. Patient education and directing the patients towards dystonia support groups and relevant websites that provide scientific information may be useful for long-term compliance and benefit.
Complex regional pain syndrome (CRPS) may occur after trauma, usually to one limb, and is characterized by pain and disturbed blood flow, temperature regulation and motor control. Approximately 25% of cases develop fixed dystonia. Involvement of dysfunctional GABAergic interneurons has been suggested, however the mechanisms that underpin fixed dystonia are still unknown. We hypothesized that dystonia could be the result of aberrant proprioceptive reflex strengths of position, velocity or force feedback.
We systematically characterized the pattern of dystonia in 85 CRPS-patients with dystonia according to the posture held at each joint of the affected limb. We compared the patterns with a neuromuscular computer model simulating aberrations of proprioceptive reflexes. The computer model consists of an antagonistic muscle pair with explicit contributions of the musculotendinous system and reflex pathways originating from muscle spindles and Golgi tendon organs, with time delays reflective of neural latencies. Three scenarios were simulated with the model: (i) increased reflex sensitivity (increased sensitivity of the agonistic and antagonistic reflex loops); (ii) imbalanced reflex sensitivity (increased sensitivity of the agonistic reflex loop); (iii) imbalanced reflex offset (an offset to the reflex output of the agonistic proprioceptors).
For the arm, fixed postures were present in 123 arms of 77 patients. The dominant pattern involved flexion of the fingers (116/123), the wrists (41/123) and elbows (38/123). For the leg, fixed postures were present in 114 legs of 77 patients. The dominant pattern was plantar flexion of the toes (55/114 legs), plantar flexion and inversion of the ankle (73/114) and flexion of the knee (55/114).Only the computer simulations of imbalanced reflex sensitivity to muscle force from Golgi tendon organs caused patterns that closely resembled the observed patient characteristics. In parallel experiments using robot manipulators we have shown that patients with dystonia were less able to adapt their force feedback strength.
Findings derived from a neuromuscular model suggest that aberrant force feedback regulation from Golgi tendon organs involving an inhibitory interneuron may underpin the typical fixed flexion postures in CRPS patients with dystonia.
Fixed dystonia is a disabling disorder mainly affecting young women who develop fixed abnormal limb postures and pain after apparently minor peripheral injury. There is continued debate regarding its pathophysiology and management. We report 5 cases of fixed dystonia in patients who sought amputation of the affected limb. We place these cases in the context of previous reports of patients with healthy limbs and patients with chronic regional pain syndrome who have sought amputation. Our cases, combined with recent data regarding disorders of mental rotation in patients with fixed dystonia, as well as previous data regarding body integrity identity disorder and amputations sought by patients with chronic regional pain syndrome, raise the possibility that patients with fixed dystonia might have a deficit in body schema that predisposes them to developing fixed dystonia and drives some to seek amputation. The outcome of amputation in fixed dystonia is invariably unfavorable.
We describe the clinical features of 103 patients presenting with fixed dystonia and report the prospective assessment and investigation of 41 of them. Most patients were female (84%) and had a young age of onset [mean 29.7 (SD 13.1) years]. A peripheral injury preceded onset in 63% and spread of dystonia to other body regions occurred in 56%. After an average follow-up of 3.3 years (overall disease duration 8.6 years), partial (19%) or complete (8%) remission had occurred in a minority of patients. The fixed postures affected predominantly the limbs (90%), and rarely the neck/shoulder region (6%) or jaw (4%). In the prospectively studied group, pain was present in most patients and was a major complaint in 41%. Twenty percent of patients fulfilled criteria for Complex Regional Pain Syndrome (CRPS). No consistent investigational abnormalities were found and no patient tested (n = 25) had a mutation in the DYT1 gene. Thirty-seven percent of patients fulfilled classification criteria for documented or clinically established psychogenic dystonia; 29% fulfilled DSM-IV (Diagnostic and statistical manual of mental disorders, 4th edition) criteria for somatization disorder, which was diagnosed only after examination of the primary care records in many cases; and 24% fulfilled both sets of criteria. Ten percent of the prospectively studied and 45% of the retrospectively studied patients did not have any evidence of psychogenic dystonia, and detailed investigation failed to reveal an alternative explanation for their clinical presentation. Detailed, semi-structured neuropsychiatric assessments in a subgroup of 26 patients with fixed dystonia and in a control group of 20 patients with classical dystonia revealed dissociative (42 versus 0%, P = 0.001) and affective disorders (85 versus 50%, P = 0.01) significantly more commonly in the fixed dystonia group. Medical and surgical treatment was largely unsuccessful. However, seven patients who underwent multidisciplinary treatment, including physiotherapy and psychotherapy, experienced partial or complete remission. We conclude that fixed dystonia usually, but not always, occurs after a peripheral injury and overlaps with CRPS. Investigations are typically normal, but many patients fulfil strict criteria for a somatoform disorder/psychogenic dystonia. In a proportion of patients, however, no conclusive features of somatoform disorder or psychogenic disorder can be found and, in these patients, whether this disorder is primarily neurological or psychiatric remains an open question. Whilst the prognosis is overall poor, remissions do occur, particularly in those patients who are willing and able to undergo multidisciplinary treatment including physiotherapy and psychotherapy, suggesting that this type of treatment should be recommended to these patients.
The dystonias are a large and heterogenous group of disorders characterized by excessive muscle contractions leading to abnormal postures and/or repetitive movements. Their clinical manifestations vary widely, and there are many potential causes. Despite the heterogeneity, helpful treatments are available for the vast majority of patients. Symptom-based therapies include oral medications, botulinum toxins, and surgical interventions. For some subtypes of dystonia, specific mechanism-based treatments are available. Advances in understanding the biological basis for many types of dystonia have led to numerous recent clinical trials, so additional treatments are likely to become available in the very near future.
Dystonia is a neurological condition characterized by abnormal involuntary movements or postures owing to sustained or intermittent muscle contractions. Dystonia can be the manifesting neurological sign of many disorders, either in isolation (isolated dystonia) or with additional signs (combined dystonia). The main focus of this Primer is forms of isolated dystonia of idiopathic or genetic aetiology. These disorders differ in manifestations and severity but can affect all age groups and lead to substantial disability and impaired quality of life. The discovery of genes underlying the mendelian forms of isolated or combined dystonia has led to a better understanding of its pathophysiology. In some of the most common genetic dystonias, such as those caused by TOR1A, THAP1, GCH1 and KMT2B mutations, and idiopathic dystonia, these mechanisms include abnormalities in transcriptional regulation, striatal dopaminergic signalling and synaptic plasticity and a loss of inhibition at neuronal circuits. The diagnosis of dystonia is largely based on clinical signs, and the diagnosis and aetiological definition of this disorder remain a challenge. Effective symptomatic treatments with pharmacological therapy (anticholinergics), intramuscular botulinum toxin injection and deep brain stimulation are available; however, future research will hopefully lead to reliable biomarkers, better treatments and cure of this disorder.
Although currently lacking a sensitive and specific electrophysiologic battery test, functional (psychogenic) dystonia can sometimes be diagnosed with clinically definite certainty using available criteria. Certain regional phenotypes have been recognized as distinctive, such as unilateral lip and jaw deviation, laterocollis with ipsilateral shoulder elevation and contralateral shoulder depression, fixed wrist and finger flexion with relative sparing of the thumb and index fingers, and fixed foot plantar flexion and inversion. The pathophysiologic abnormalities in functional dystonia overlap substantially with those of organic dystonia, with similar impairments in cortical and spinal inhibition and somatosensory processing, but with emerging data suggesting abnormalities in regional blood flow and activation patterns on positron emission tomography and functional magnetic resonance imaging, respectively. Management of functional dystonia begins with compassionate and assertive debriefing of the diagnosis to ensure full acceptance by the patient, a critical step in enhancing the likelihood of success with physical rehabilitation, and psychodynamic or cognitive therapy. Physical therapy, with or without cognitive behavioral therapy, appears to be of benefit but has not yet been examined in a controlled fashion. While the prognosis remains grim for a substantial majority of patients, partly stemming from restricted mobility, delayed diagnosis, and inappropriate pharmacotherapy, early recognition and initiation of therapy stand to minimize iatrogenic harm and unnecessary laboratory investigations, and potentially reduce the long-term neurologic disability.
Purpose of review:
The review highlights the most relevant recent developments in the field of functional movement disorders (FMD).
Recent findings:
The emphasis on making a 'positive' diagnosis has driven a renewed interest in assessing the value of simple clinical signs. Furthermore, an effort has been made to develop and test objective diagnostic tools. The association of FMD with several comorbidities is being acknowledged. Pathophysiological understanding has grown with the identification of new neurobiological abnormalities, including a decreased interoceptive sensitivity. Finally - and most importantly - the recognition of the potential benefits of specialized physiotherapy is changing FMD management.
Summary:
The field of FMD is moving forward on a number of fronts, including diagnosis, pathophysiology, and treatment. A major priority for future research is providing robust evidence regarding treatment.
From the very first descriptions of dystonia, there has been a lack of agreement on the differentiation of organic from functional (psychogenic) dystonia. This lack of agreement has had a significant effect on patients over the years, most particularly in the lack of access to appropriate management, whether for those with organic dystonia diagnosed as having a functional cause or vice versa. However, clinico-genetic advances have led to greater certainty about the phenomenology of organic dystonia and therefore recognition of atypical forms. The diagnosis of functional dystonia rests on recognition of its phenomenology and should not be, as far as possible, a diagnosis of exclusion. Here, we present an overview of the phenomenology of functional dystonia, concentrating on the three main phenotypic presentations: functional cranial dystonia; functional fixed dystonia; and functional paroxysmal dystonia. We hope that this review of phenomenology will aid in the positive diagnosis of functional dystonia and, through this, will lead to more rapid access to appropriate management.
This report describes the consensus outcome of an international panel consisting of investigators with years of experience in this field that reviewed the definition and classification of dystonia. Agreement was obtained based on a consensus development methodology during 3 in-person meetings and manuscript review by mail. Dystonia is defined as a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. Dystonic movements are typically patterned and twisting, and may be tremulous. Dystonia is often initiated or worsened by voluntary action and associated with overflow muscle activation. Dystonia is classified along 2 axes: clinical characteristics, including age at onset, body distribution, temporal pattern and associated features (additional movement disorders or neurological features); and etiology, which includes nervous system pathology and inheritance. The clinical characteristics fall into several specific dystonia syndromes that help to guide diagnosis and treatment. We provide here a new general definition of dystonia and propose a new classification. We encourage clinicians and researchers to use these innovative definition and classification and test them in the clinical setting on a variety of patients with dystonia. © 2013 Movement Disorder Society.
The syndrome of fixed dystonia includes both CRPS-dystonia and psychogenic dystonia. The underlying mechanisms are unclear, but a high prevalence of neuropsychiatric illness has previously been reported.
Clinical and neuropsychiatric follow-up study by telephone and self-administered instruments (HADS, SDQ-20, DES II, EQ-5D), on 41 patients with fixed dystonia after a mean of 7.6 (+/-3.6) years.
We obtained information on clinical outcome in 35 (85.4%) patients and neuropsychiatric questionnaire data in 22 (53.7%). Eighty-three percent were women. Thirty-one percent had worsened, 46% were the same and 23% had improved, of whom 6% had major remissions. At follow-up, mean duration of illness was 11.8 (+/-4.9) years and mean age 43.2 (+/-14.8) years. Except for 1 patient who was re-diagnosed with corticobasal degeneration, the diagnosis remained unchanged in others. Forty-one percent had scores indicating anxiety and 18% indicating depression; 18% scored within the range of dissociative/somatoform disorders on DES II and 19% on SDQ-20. The mean EQ-5D index and VAS scores were 0.34 and 56.1%. Comparison between the 3 outcome groups revealed significant difference only in the EQ-5D (p=0.003). Only baseline CRPS predicted a worse outcome (chi(2)=0.006).
Our findings revealed that the prognosis of this syndrome is poor, with improvement in less than 25% of patients, major remission in only 6% and continued worsening in a third. A high rate of neuropsychiatric findings was noted and new neuropsychiatric features had occurred in some. Average health status was poor. Of the baseline parameters, only CRPS predicted poorer outcome.
The clinical features and prognosis of 42 patients with idiopathic torsion dystonia were reviewed. There were striking differences between those with onset in childhood and those in whom the illness began in adult life, in respect to site of onset and prognosis. The disease began before the age of 15 yr in 60% of patients, most commonly as an abnormality of gait. In 72% of children with torsion dystonia the disease progressed, usually over the first 5 to 10 yr to generalized dystonia and often to severe disability. Speech and swallowing were often affected. Torsion dystonia with onset in adult life usually began with dystonia of the arms or trunk, progressed to generalized dystonia in only 18% of cases, and rarely caused severe disability. Idiopathic torsion dystonia appeared to be a more benign disease than is usually appreciated. About 1/3 of patients, most of whom developed symptoms in childhood, were bed or chair ridden; 1/3 were moderately disabled; and 1/3 were mildly disabled but independent. The incidence of a family history in this material was low, consisting of 4 patients with an affected sibling or cousin and no examples of autosomal dominant inheritance were encountered. A review of the effects of treatment suggested that drugs were not of striking value, but that those which induce parkinsonism are most likely to be effective. Surgery, in the form of stereotactic thalamotomy, certainly benefited some patients, particularly those with dystonia confined to an arm or arm and neck. Bilateral stereotactic surgery produced temporary benefit in most patients with progressive generalized dystonia. The pathology of the disease is unknown but it is postulated that inherited biochemical abnormalities of basal ganglia function may prove to be the cause.
We report 18 patients (16 women and two men) with causalgia and dystonia, triggered by peripheral injuries in 15 cases and occurring spontaneously in three. The injury was often trivial, and did not cause overt peripheral nerve lesions. The mean age at presentation was 28.5 years. None had a family history of dystonia. The leg was affected initially in 12 patients, the arm in the remaining six cases. All had burning pain, allodynia and hyperpathia, along with vasomotor, sudomotor and trophic changes. All developed dystonic muscle spasms in the affected part. Dystonia always appeared at the same time or after the causalgia. The spasms were typically sustained, producing a 'fixed' dystonic posture, in contrast to the mobile spasms characteristics of idiopathic torsion dystonia. There was spread of the causalgia and of the dystonia from its initial site both in the affected limb and to other extremities, the latter in hemiplegic, transverse and triplegic distribution. All investigations were normal. All modes of conventional treatment failed to relieve either the pain or the dystonia, but two patients recovered spontaneously. At present it is impossible to decide whether this distressing syndrome is a true functional disorder of the central nervous system, or is of psychogenic origin.
Although the potential for musculoskeletal symptoms in hysteric conversion disorder was recognized by Sigmund Freud, reports of it in the orthopaedic literature have been limited to upper extremity manifestations. This study reports 3 cases which illustrate hysteric conversion presenting as primary foot and ankle complaints. Given its relative rarity, it is a diagnosis that is easy to miss. Clinical clues to its diagnosis and accepted methods of treatment are discussed. It is important to realize that this condition arises from an unconscious conflict and does not represent a voluntary falsification of symptoms. As such, confrontational treatment is not generally successful.
The lower extremity is affected infrequently in adult-onset primary dystonia in contrast to childhood-onset dystonia, which typically begins in the foot. When dystonia affects the foot in an adult, it is usually on a secondary basis. We present findings on 17 patients (11 women, 6 men; average age of onset 48.4 years; average time to diagnosis 2.7 years) with adult-onset primary foot dystonia. Prior to diagnosis, most patients underwent extensive testing and treatment, including unnecessary surgeries. Only the left lower extremity was involved in 8 patients, only the right in 7, and both in 2. The most common patterns were plantar flexion of all toes and inversion of the foot, typically activated with standing or walking. Only 2 patients had dystonia elsewhere. There was a family history of possible dystonia in 2 patients. One of five tested for DYT1 was positive, in the absence of a family history. One of eight patients treated with levodopa experienced mild improvement. Six of eight treated with botulinum toxin improved. No patient has been observed to have a secondary cause of dystonia. The prognosis, with regard to progression or spread to other body parts, has been favorable. Although uncommon, foot dystonia on a primary basis, not due to DYT1, can begin in adulthood. In this series of patients, the diagnosis was often not recognized, leading to extensive and unnecessary testing and treatment and emphasizing the need for wider recognition.