Can peripheral trauma induce dystonia? No!

Peripherally-induced Movement Disorders: An Update

Background

Peripherally-induced movement disorders (PIMD) should be considered when involuntary or abnormal movements emerge shortly after an injury to a body part. A close topographic and temporal association between peripheral injury and onset of the movement disorders is crucial to diagnosing PIMD. PIMD is under-recognized and often misdiagnosed as functional movement disorder, although both may co-exist. Given the considerable diagnostic, therapeutic, and psychosocial-legal challenges associated with PIMD, it is crucial to update the clinical and scientific information about this important movement disorder.

Methods

A comprehensive PubMed search through a broad range of keywords and combinations was performed in February 2023 to identify relevant articles for this narrative review.

Results

The spectrum of the phenomenology of PIMD is broad and it encompasses both hyperkinetic and hypokinetic movements. Hemifacial spasm is probably the most common PIMD. Others include dystonia, tremor, parkinsonism, myoclonus, painful leg moving toe syndrome, tics, polyminimyoclonus, and amputation stump dyskinesia. We also highlight conditions such as neuropathic tremor, pseudoathetosis, and MYBPC1-associated myogenic tremor as examples of PIMD.

Discussion

There is considerable heterogeneity among PIMD in terms of severity and nature of injury, natural course, association with pain, and response to treatment. As some patients may have co-existing functional movement disorder, neurologists should be able to differentiate the two disorders. While the exact pathophysiology remains elusive, aberrant central sensitization after peripheral stimuli and maladaptive plasticity in the sensorimotor cortex, on a background of genetic (two-hit hypothesis) or other predisposition, seem to play a role in the pathogenesis of PIMD.

Mild traumatic brain injury and sports-related concussion

Mild traumatic brain injury (mTBI) and concussion are equivalent terms for the sequela of injury to the head that disrupts brain functioning. Various forces may be causative from seemingly innocuous bumps to the head resulting from sports-related injuries to more severe blows to the head. However, the postconcussive motor, cognitive, emotional, and psychosocial sequelae can be just as devastating and long lasting, leading to loss of independent function and safe performance of activities. Taken together, they pose a significant challenge to recovery, requiring a multifaceted dynamic rehabilitative strategy. The current systems of health care pose challenges to suboptimal management of sports-related concussion (SRC) that goes beyond the acute injury, and into the school setting, failing to be identified by school staff, and inconsistencies in communicating medical information regarding school modifications, follow-up health services, or concussion-related educational services. Children who sustain SRC at different ages face different challenges. Young children face increased vulnerability due to SRC that coincides with periods of brain motor maturation and development.

Surgical outcome of a post-traumatic dystonic foot: Case report and literature review

Post-traumatic dystonia is an underrecognized condition that can present with bizarre symptoms after trauma, usually out of proportion to the trigger event. We describe the case of a 31-year-old man with a severe lower extremity deformity, gradually developed after minor trauma. An interdisciplinary treatment was tried without any improvement and surgery was performed as a rescue approach. Tibialis anterior tendon transfer and hindfoot triple arthrodesis were carried out, successfully achieving a plantigrade foot and a functional gait. Despite the scarce literature available about functional results of surgery in dystonic feet, we present a step-by-step comprehensive approach to this disorder. LEVEL OF CLINICAL EVIDENCE: 4.

Posttraumatic functional movement disorders and litigation

The concept of functional movement disorders has evolved considerably over the past few decades. More specifically, the views on the relation with psychological stressors or personality disorders have substantially changed, emphasizing a shift from the previously dominant dualistic scheme. This evolution is reflected in adaptations to diagnostic criteria and management approaches. Functional movement disorders which arise in a close temporal relationship with a peripheral trauma are specifically challenging with respect to diagnosis and treatment, but similar considerations seem to apply. The relationship of functional disorders with trauma appears to be much closer than is often thought. Clinical and pathophysiological research has identified shared factors underlying functional posttraumatic as well as primary movement disorders. These evolving insights impact on discussions in terms of litigation for compensation after trauma. The literature is reviewed and the consequences for argumentation in litigation are outlined, including ethical and legal considerations. Finally, we formulate a number of recommendations.

Cervical dystonia incidence and diagnostic delay in a multiethnic population

BACKGROUND

Current cervical dystonia (CD) incidence estimates are based on small numbers in relatively ethnically homogenous populations. The frequency and consequences of delayed CD diagnosis is poorly characterized.

OBJECTIVES

To determine CD incidence and characterize CD diagnostic delay within a large, multiethnic integrated health maintenance organization.

METHODS

We identified incident CD cases using electronic medical records and multistage screening of more than 3 million Kaiser Permanente Northern California members from January 1, 2003, to December 31, 2007. A final diagnosis was made by movement disorders specialist consensus. Diagnostic delay was measured by questionnaire and health utilization data. Incidence rates were estimated assuming a Poisson distribution of cases and directly standardized to the 2000 U.S. census. Multivariate logistic regression models were employed to assess diagnoses and behaviors preceding CD compared with matched controls, adjusting for age, sex, and membership duration.

RESULTS

CD incidence was 1.18/100,000 person-years (95% confidence interval [CI], 0.35-2.0; women, 1.81; men, 0.52) based on 200 cases over 15.4 million person-years. Incidence increased with age. Half of the CD patients interviewed reported diagnostic delay. Diagnoses more common in CD patients before the index date included essential tremor (odds ratio [OR] 68.1; 95% CI, 28.2-164.5), cervical disc disease (OR 3.83; 95% CI, 2.8-5.2), neck sprain/strain (OR 2.77; 95% CI, 1.99-3.62), anxiety (OR 2.24; 95% CI, 1.63-3.11) and depression (OR 1.94; 95% CI, 1.4-2.68).

CONCLUSIONS

CD incidence is greater in women and increases with age. Diagnostic delay is common and associated with adverse effects. © 2019 International Parkinson and Movement Disorder Society.

Posttraumatic functional movement disorders

Traumatic injury to the nervous system may account for a range of neurologic symptoms. Trauma location and severity are important determinants of the resulting symptoms. In severe head injury with structural brain abnormalities, the occurrence of trauma-induced movement disorders, most commonly hyperkinesias such as tremor and dystonia, is well recognized and its diagnosis straightforward. However, the association of minor traumatic events, which do not lead to significant persistent structural brain damage, with the onset of movement disorders is more contentious. The lack of clear clinical-neuroanatomic (or symptom lesion) correlations in these cases, the variable timing between traumatic event and symptom onset, but also the presence of unusual clinical features in a number of such patients, which overlap with signs encountered in patients with functional neurologic disorders, contribute to this controversy. The purpose of this chapter is to provide an overview of the movement disorders, most notably dystonia, that have been associated with peripheral trauma and focus on their unusual characteristics, as well as their overlap with functional neurologic disorders. We will then provide details on pathophysiologic views that relate minor peripheral injuries to the development of movement disorders and compare them to knowledge from primary organic and functional movement disorders. Finally, we will comment on the appropriate management of these disorders.

Movement disorders secondary to craniocerebral trauma

Over the past few decades it has been recognized that traumatic brain injury may result in various movement disorders. In survivors of severe head injury, post-traumatic movement disorders were reported in about 20%, and they persisted in about 10% of patients. The most frequent persisting movement disorder in this population is kinetic cerebellar outflow tremor in about 9%, followed by dystonia in about 4%. While tremor is associated most frequently with cerebellar or mesencephalic lesions, patients with dystonia frequently have basal ganglia or thalamic lesions. Moderate or mild traumatic brain injury only rarely causes persistent post-traumatic movement disorders. It appears that the frequency of post-traumatic movement disorders overall has been declining which most likely is secondary to improved treatment of brain injury. In patients with disabling post-traumatic movement disorders which are refractory to medical treatment, stereotactic neurosurgery can provide long-lasting benefit. While in the past the primary option for severe kinetic tremor was thalamotomy and for dystonia thalamotomy or pallidotomy, today deep brain stimulation has become the preferred treatment. Parkinsonism is a rare consequence of single head injury, but repeated head injury such as seen in boxing can result in chronic encephalopathy with parkinsonian features. While there is still controversy whether or not head injury is a risk factor for the development of Parkinson's disease, recent studies indicate that genetic susceptibility might be relevant.

Posttraumatic focal dystonia of the shoulder

Focal posttraumatic shoulder dystonia is a rare and not easily identifiable entity. Its true pathophysiologic nature, predisposing factors, and disease course remain debatable.This article describes a rare case of a 40-year-old man with late symptoms of focal shoulder dystonia after peripheral trauma of his left shoulder girdle. The shoulder was indirectly injured from the impact of a fall off his motorbike 3 years earlier. He was referred to the authors' institution because remarkable reduction of arm abduction, muscle spasms, and circumscribed hypertrophy of the trapezius muscle were noted while his head and neck were in neutral position and had a full range of motion. The left shoulder had a fixed elevated posture compared with the contralateral shoulder. A continuous burning pain was localized over the area of the hypertrophied trapezius muscle, radiating to the ipsilateral side of the head and neck. Dystonic movements of the trapezius, rhomboid, and supraspinatus muscles were observed. The abduction of the shoulder was significantly decreased, and any repetitive effort for arm abduction induced an exaggeration of his movement disorder, leading to a more pronounced shoulder elevation.Plain radiographs and magnetic resonance imaging of the left shoulder revealed a suprascapular tendinitis with no other abnormalities. Repeated needle electromyography of the left trapezius muscle and neurography of the accessory nerve on both sides were normal. Injections of botulinum toxin A were effective in the resolution of muscle hypertrophy and abnormal posture.

Painful legs and moving toes

The syndrome of painful legs-moving toes (PLMT) is an adult-onset, rare disorder characterized by pain, typically of a neuropathic quality, in the feet or legs, associated with writhing movements of one or more toes. It is the pain which usually brings the patient to medical attention. The syndrome may be unilateral or bilateral. Identical toe movements may occur without pain, referred to as: "painless legs-moving toes," and a similar condition affects the upper limbs: "painful arms-moving fingers." The pathophysiology of PLMT and its variants is not known but most reports suggest an association with a peripheral lesion, usually at the level of the root or nerve, though in many cases no cause is found. It has been suggested that a peripheral lesion causes aberrant input leading to "central reorganization," probably at the level of the spinal cord, and that the latter is responsible for the pain and movement. Treatment is often unsatisfactory and many drugs commonly used for neuropathic pain have been reported anecdotally to help (e.g., gabapentin). Other anecdotal therapies include spinal blocks, spinal cord stimulation, and local injection of botulinum toxin.

Peripheral trauma induced dystonia or post-traumatic syndrome?

The relationship between peripheral trauma and dystonia has been debated for more than a century but the issue still remains controversial. There are passionate supporters and detractors of the association and both the groups have their own arguments. This review aims to critically evaluate those arguments and presents current understanding of this association. In the process, the relevant case series and scientific papers exploring this subject have been discussed. Upon careful review of available literature coupled with their own experience, the authors believe that peripheral trauma can predispose to abnormal posturing of a body part after variable intervals. To call this posturing a "post-traumatic dystonia" might be premature and the term "post-traumatic syndrome" can be used instead. More work is needed to unravel the pathophysiology of this post-traumatic syndrome.

Adult-onset dystonia

Dystonia is defined as involuntary sustained muscle contractions producing twisting or squeezing movements and abnormal postures. The movements can be stereotyped and repetitive and they may vary in speed from rapid to slow; sustained contractions can result in fixed postures. Dystonic disorders are classified into primary and secondary forms. Several types of adult-onset primary dystonia have been identified but all share the characteristic that dystonia (including tremor) is the sole neurologic feature. The forms most commonly seen in neurological practice include cranial dystonia (blepharospasm, oromandibular and lingual dystonia and spasmodic dysphonia), cervical dystonia (also known as spasmodic torticollis) and writer's cramp. These are the disorders that benefit most from botulinum toxin injections. A general characteristic of dystonia is that the movements or postures may occur in relation to specific voluntary actions by the involved muscle groups (such as in writer's cramp). Dystonic contractions may occur in one body segment with movement of another (overflow dystonia). With progression, dystonia often becomes present at rest. Dystonic movements typically worsen with anxiety, heightened emotions, and fatigue, decrease with relaxation, and disappear during sleep. There may be diurnal fluctuations in the dystonia, which manifest as little or no involuntary movement in the morning followed by severe disabling dystonia in the afternoon and evening. Morning improvement (or honeymoon) is seen with several types of dystonia. Patients often discover maneuvers that reduce the dystonia and which involve sensory stimuli such as touching the chin lightly in cervical dystonia. These maneuvers are known as sensory tricks, or gestes antagonistes. This chapter focuses on adult-onset focal dystonias including cranial dystonia, cervical dystonia, and writer's cramp. The chapter begins with a review of the epidemiology of focal dystonias, followed by discussions of each major type of focal dystonia, covering clinical phenomenology, differential genetics, and diagnosis. The chapter concludes with discussions of the pathophysiology, the few pathological cases published of adult-onset focal dystonia and management options, and a a brief look at the future.

Nonprimary dystonias

Dystonias can be classified as primary or secondary, as dystonia-plus syndromes, and as heredodegenerative dystonias. Their prevalence is difficult to determine. In our experience 80-90% of all dystonias are primary. About 20-30% of those have a genetic background; 10-20% are secondary, with tardive dystonia and dystonia in cerebral palsy being the most common forms. If dystonia in spastic conditions is accepted as secondary dystonia, this is the most common form of all dystonia. In primary dystonias, the dystonic movements are the only symptoms. In secondary dystonias, dystonic movements result from exogenous processes directly or indirectly affecting brain parenchyma. They may be caused by focal and diffuse brain damage, drugs, chemical agents, physical interactions with the central nervous system, and indirect central nervous system effects. Dystonia-plus syndromes describe brain parenchyma processes producing predominantly dystonia together with other movement disorders. They include dopa-responsive dystonia and myoclonus-dystonia. Heredodegenerative dystonias are dystonic movements occurring in the context of other heredodegenerative disorders. They may be caused by impaired energy metabolism, impaired systemic metabolism, storage of noxious substances, oligonucleotid repeats and other processes. Pseudodystonias mimic dystonia and include psychogenic dystonia and various orthopedic, ophthalmologic, vestibular, and traumatic conditions. Unusual manifestations, unusual age of onset, suspect family history, suspect medical history, and additional signs may indicate nonprimary dystonia. If they are suspected, etiological clarification becomes necessary. Unfortunately, potential etiologies are legion. Diagnostic algorithms can be helpful. Treatment of nonprimary dystonias, with few exceptions, does not differ from treatment of primary dystonias. The most effective treatment for focal and segmental dystonias is local botulinum toxin injections. Deep brain stimulation of the globus pallidus internus is effective for generalized dystonia. Antidystonic drugs, including anticholinergics, tetrabenazine, clozapine, and gamma-aminobutyric acid receptor agonists, are less effective and often produce adverse effects. Dopamine is extremely effective in dopa-responsive dystonia. The Bertrand procedure can be effective in cervical dystonia. Other peripheral surgery, including myotomy, myectomy, neurotomy, rhizotomy, ramizectomy, and accessory nerve neurolysis, has largely been abandoned. Central surgery other than deep brain stimulation is obsolete. Adjuvant therapies, including orthoses, physiotherapy, ergotherapy, behavioral therapy, social support, and support groups, may be helpful. Analgesics should also be considered where appropriate.

Four cases with peripheral trauma induced involuntary movements

Background and Purpose

Although peripheral trauma induced movement disorders have been rarely reported, diagnostic criteria for peripherally induced movement disorders (PIMD) have been established. Because preexisting subclinical movement disorders, or secondary gain for compensation and legal purposes are difficult to confirm, differential diagnosis for physicians still remains difficult.

Case Reports

We present four patients developed movement disorders after relatively various intervals after traffic accident. Three patients of them showed tremor and one patient presented propriospinal myoclonus. In this report, we investigate whether peripheral trauma can lead to movement disorders and describe the relationship between peripheral injury and movement disorders in four cases.

Conclusions

Injury was serious enough to develop involuntary abnormal movements with pain and the latency between injury and the onset of movements in all of cases was less than 1 year. Thus, our cases showed temporal and anatomical correlation between injury and the onset of movement disorder, strongly supporting the cause-and-effect relationship by previous diagnostic criteria for peripherally induced movement disorders.

Syndrome of fixed dystonia in adolescents--short term outcome in 4 cases

We describe the clinical features, investigations and outcome of 4 adolescents aged 13, 16, 17 and 19 years, with fixed dystonia. The diagnosis was made within 6 months of the onset of symptoms. One patient had an identifiable traumatic precipitant. All the affected extremities had pain, sudomotor and vascular changes which were consistent with complex regional pain syndrome. The extremities affected by dystonia were the foot and the hand. The dystonia spread to affect other extremities in one patient. One patient had hemifacial spasm. Examination of the central and peripheral nervous system and allied investigations failed to reveal an organic cause. Common genetic causes for dystonia were excluded. The response to physical treatments for the affected extremities, such as Botulinum Toxin and surgery was poor. In all our cases there were significant psychological and psychiatric factors. Three patients fully met the criteria for psychogenic dystonia and responded well to psychological intervention. Fixed dystonia in adolescents is an uncommon disorder of unknown aetiology, usually presenting in girls, which can be very disabling and difficult to treat. The affected parts of the body are usually painful and show vascular changes. The condition is allied to CRPS. Treatment with multidisciplinary approach including psychological measures and physiotherapy is more likely to be successful and may prevent unnecessary physical measures.

[Post-traumatic focal fixed dystonia of the shoulder: a distinctive syndrome with speculative mechanisms?]

INTRODUCTION

Whether post-traumatic focal fixed dystonia has a physiological or psychologically-mediated mechanism is discussed.

CASE REPORT

We report the case of an active 22-year-old soldier with shoulder-fixed dystonia, eight months after a fall with minor right-acromioclavicular sprain.

CONCLUSION

Psychiatric examination and search of complex regional pain syndrome, radicular or accessory nerve damage, and genetic predisposition to dystonia are necessary for selecting a difficult treatment in these patients.

Transient tardive dystonia: overview and case presentation

Dystonia is a syndrome of involuntary, repetitive (or sustained) muscle contractions of opposing muscles, which may result in torsions and abnormal postures. Tardive dystonia is a form of the disorder that starts after longer term use of dopamine antagonists. It occurs in approximately 3% of patients receiving ongoing antipsychotic treatment and is often difficult to reverse. Dystonia can also be induced by compounds other than antipsychotics, such as antidepressants, levodopa, carbamazepine, dextroamphetamine, and diphenylhydantoin. In these cases, it is transient, generally disappearing after the dose is reduced or the causative drug is stopped. Dystonia induced by injury can also be transient. We report a case of transient oromandibular dystonia following a dental filling in a woman receiving quetiapine, a second-generation antipsychotic. The timing, localization, and transience of the dystonia suggested that the dental procedure may have played a triggering role. The dystonia symptoms responded within 8 weeks to benztropine and a dose reduction of quetiapine, and they did not return when benztropine was discontinued. This case benefited from prompt attention and has led to practical recommendations for psychiatric clinicians.

Trauma-induced dystonia and camptocormia in a child

A 14-year-old male sustained neck trauma during a fight at school. Torticollis developed immediately afterwards, followed by axial dystonia and camptocormia. Thorough evaluation for etiology or background disease, including psychiatric examination, was negative except for the recent trauma. Antidystonia medications, administered after significant worsening of the symptoms, led to improvement. Dystonia and camptocormia resulting from trauma are rare presentations in childhood and adolescence.

Abnormality of motor cortex excitability in peripherally induced dystonia

It is widely accepted that peripheral trauma such as soft tissue injuries can trigger dystonia, although little is known about the underlying mechanism. Because peripheral injury only rarely appears to elicit dystonia, a predisposing vulnerability in cortical motor areas might play a role. Using single and paired-pulse pulse transcranial magnetic stimulation, we evaluated motor cortex excitability of a hand muscle in a patient with peripherally induced foot dystonia, in her brother with craniocervical dystonia, and in her unaffected sister, and compared their results to those from a group of normal subjects. In the patient with peripherally induced dystonia, we found a paradoxical intracortical facilitation at short interstimulus intervals of 3 and 5 milliseconds, at which regular intracortical inhibition (ICI) occurred in healthy subjects. These findings suggest that the foot dystonia may have been precipitated as the result of a preexisting abnormality of motor cortex excitability. Furthermore, the abnormality of ICI in her brother and sister indicates that altered motor excitability may be a hereditary predisposition. The study demonstrates that the paired-pulse technique is a useful tool to assess individual vulnerability, which can be particularly relevant when the causal association between trauma and dystonia is less evident.

Complete suppression of paroxysmal nonkinesigenic dyskinesia by globus pallidus internus pallidal stimulation

Stereotactic functional surgery is being explored as potential therapies for medically intractable paroxysmal dyskinesias (PxD). We report on a 59-year-old man in whom stimulation of globus pallidus internus produced immediate and sustained relief of paroxysmal non-kinesigenic dyskinesia secondary to a rotator cuff tears on the left shoulder. Our finding strongly suggests that altered function of neuronal circuits of the basal ganglia underlies the manifestation of PxD.

Movement disorders in Latin America

The authors review some particularities of movement disorders (MDs) in the ethnically diverse population of Latin America. Although idiopathic diseases are evenly prevalent, access to treatment encounters difficulties that are worth discussing. Infectious-parasitic diseases observed throughout the continent occasionally present as MDs, and will be individually reviewed. Inherited MDs with regional foci of increased prevalence, particularly spinocerebellar ataxias, will also be considered. Whereas there is no treatment for genetic disorders, most of the other conditions are preventable or amenable to adequate treatment. Hope for better health standards for the Latin American population lies in profound social and political changes that are still to come.

Dystonia after a bone fracture of the arm in a patient with a history of striato-pallidal ischemic stroke: a case report

We report on a female with segmental dystonia of the upper limb after an anatomically related ischemic stroke. Dystonia developed almost 3 years after the onset of the stroke and immediately following the removal of the cast because of a bone fracture in the same limb. We discuss the case considering issues such as: delay-onset, lesion topography and pathophysiology, peripheral input and their possible contribution to the development of secondary dystonia.

Natural history of posttraumatic cervical dystonia

We studied a case series of 9 patients with posttraumatic cervical dystonia, in whom involuntary muscle spasms and abnormal head postures occurred within 7 days after cervical injury. Patients were examined, treated with botulinum toxin as necessary, and were followed up to 5 years. Based on our observations of these cases, we propose that complex regional pain syndrome (CRPS) could represent a variant of posttraumatic cervical dystonia that may develop over time after the initiation of dystonia.

Persistent abnormal shoulder elevation after accessory nerve injury and differential diagnosis with post-traumatic focal shoulder-elevation dystonia: report of a case and literature review

We report on a patient with persistent abnormal shoulder posture associated with isolated neurogenic hypertrophy of the trapezius muscle due to accessory nerve injury. The patient complained of marked difficulty in shoulder elevation and abduction. Over 6-month treatment with botulinum toxin, there was a complete resolution.

Movement disorders after intervertebral disc surgery: Coincidence or causal relationship?

It is well known that brain injury or central traumatic lesions may result in the subsequent appearance of movement disorders such as dystonia or tremor. The concept that peripheral lesions to neural structures may be involved in the pathogenesis of movement disorders has been discussed controversely but has gained more widespread acceptance only recently. Here, we report on 6 patients who developed movement disorders after spinal disc surgery. The movement disorders became manifest with a delay of 1 day to 12 months after surgery. Of the six patients, 4 underwent cervical disc surgery, and 2 patients were operated on for lumbar disc herniation; 2 patients presented with paroxysmal kinesigenic segmental dystonia, 1 patient with focal dystonia, 2 with unilateral tremor, and 1 with bilateral tremor. The appearance of the movement disorder was associated with persistent dermatomal or segmental pain. In all patients, the anatomic distribution of the movement disorder was related to the nerve root or spinal segment of the corresponding disc level and the manifestation was in close temporal relation to the surgery. We conclude that spinal disc surgery may be another, thus far neglected, cause for movement disorders. The postoperative pain syndrome in all patients should be considered as an important factor of pathogenesis. Overall, movement disorders associated with disc surgery appear to be rare, yet they may cause significant discomfort to the affected individual.

The syndrome of fixed dystonia: an evaluation of 103 patients

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.

Posttraumatic painful torticollis

The development of abnormal posturing of the neck or shoulder after local injury has been termed posttraumatic cervical dystonia (PTCD). Certain features seem to distinguish a unique subgroup of patients with this disorder from those with features more akin to typical idiopathic cervical dystonia, such as onset and maximum disability that occurs very quickly after injury, severe pain and a fixed abnormal posture. In an attempt to clarify the nature of this syndrome further, we evaluated 16 such patients (8 men, 8 women). Motor vehicle accident and work-related injuries were common precipitants, with posturing usually developing shortly after trauma, and little progression occurring after the first week. A characteristic, painful, fixed head tilt and shoulder elevation were present in all but one patient, who had a painless elevated shoulder and painful contralateral shoulder depression, as well as nondermatomal sensory loss in 14 patients. Additional abnormalities included dystonic posturing in a limb (2 patients) or jaw (1 patient), limb tremor (3 patients) and "give-way" limb weakness (8 patients). The tremor and the jaw dystonia demonstrated features suggestive of a psychogenic movement disorder, most commonly distractibility. Litigation or compensation was present in all 16 patients. Intravenous sodium amytal improved the posture, pain or both in 13 of 13 patients; in 7 of 13 the sensory deficit either markedly improved or normalized. General anesthesia demonstrated full range of motion in all 5 patients assessed. Psychological evaluations suggested that psychological conflict, stress, or both were being expressed via somatic channels in 11 of 12 tested patients. Our results suggest an important role of psychological factors in the etiology or maintenance of abnormal posture, pain and associated disability of these patients. The role of central factors triggered in psychologically vulnerable individuals after physical trauma is discussed. We propose that the disorder be referred to as "posttraumatic painful torticollis" rather than characterize it as a form of dystonia until further information on its pathogenesis is forthcoming.

Abnormal cortical sensory activation in dystonia: an fMRI study

Despite the obvious motor manifestations of focal dystonia, it is recognised that the sensory system plays an important role in this condition. This functional magnetic resonance imaging study examines the sensory representations of individual digits both within the subregions of the primary sensory cortex (SI) and in other nonprimary sensory areas. Patients with focal dystonia and controls were scanned during vibrotactile stimulation of both the index (digit 2) and little (digit 5) fingers of their dominant hand (which was the affected hand in all the dystonic subjects). The activation maps obtained were analysed for location, size, and magnitude of activation and three-dimensional (3-D) orientation of digit representations. Data from both groups were compared. There were significant differences in the average 3-D separation between the two digit representations in area 1 of SI between subject groups (9.6 +/- 1.2 mm for controls and 4.1 +/- 0.2 mm for dystonic subjects). There were also strong trends for reversed ordering of the representation of the two digits in both the secondary sensory cortex and posterior parietal area between the two groups. In addition, in dystonic subjects, there was significant under activation in the secondary somatosensory cortex (SII/area 40) for both digits and in the posterior parietal area for digit 5. These results indicate the presence of widespread activation abnormalities in the cortical sensory system in dystonia.

Paroxysmal kinesigenic dyskinesias

The paroxysmal dyskinesias (PxDs) are involuntary, intermittent movement disorders manifested by dystonia, chorea, athetosis, ballismus or any combination of these hyperkinetic disorders. Paroxysmal kinesigenic dyskinesia (PKD), one of the four main types of PxD, involves sudden attacks of dyskinesias induced by voluntary movements. PKD most commonly occurs sporadically or as an autosomal-dominant familial trait with variable penetrance. Many causes of secondary PKD are being recognized. The exact pathophysiology of the PxDs awaits further elucidation, although basal ganglia dysfunction appears to play a major role. Although the precise gene remains unknown, genetic linkage studies have isolated loci on chromosome 16, which colocalizes with the locus for familial infantile convulsions and paroxysmal choreoathetosis in some studies. The episodic nature of PKD and its relationship with other episodic diseases, such as epilepsy, migraine, and episodic ataxia, suggests channelopathy as a possible underlying etiology. PKD may remit spontaneously, but it also responds well to anticonvulsants as well as some other agents.

Secondary paroxysmal dyskinesias

Paroxysmal dyskinesias (PxDs) are involuntary, episodic movements that include paroxysmal kinesigenic (PKD), paroxysmal nonkinesigenic (PNKD), and paroxysmal hypnogenic (PHD) varieties. Although most PxDs are primary (idiopathic or genetic), we found 17 of our 76 patients with PxD (22%) to have an identifiable cause for their PxD (10 men; mean age, 41.4 years). Causes included peripheral trauma (in three patients), vascular lesions (in four), central trauma (in four), kernicterus (in two), multiple sclerosis (in one), cytomegalovirus encephalitis (in one), meningovascular syphilis (in one), and migraine (in one). The latency from insult to symptom onset ranged from days (trauma) to 18 years (kernicterus), with a mean of 3 years. Nine patients had PNKD, two had PKD, five had mixed PKD/PNKD, and one had PHD. Hemidystonia was the most common expression of the paroxysmal movement disorder, present in 11 patients. Both of the patients with PKD had symptom durations of <5 minutes. Symptom duration ranged from 10 seconds to 15 days for PNKD and from 5 minutes to 45 minutes for mixed PKD/PNKD. There were no uniformly effective therapies, but anticonvulsant drugs, clonazepam, and botulinum toxin injections were the most beneficial. Awareness of the variable phenomenology and the spectrum of causes associated with secondary PxD will allow for more timely diagnosis and early intervention.

Head injury and posttraumatic movement disorders

WE REVIEW THE phenomenology, pathophysiology, pathological anatomy, and therapy of posttraumatic movement disorders with special emphasis on neurosurgical treatment options. We also explore possible links between craniocerebral trauma and parkinsonism. The cause-effect relationship between head injury and subsequent movement disorder is not fully appreciated. This may be related partially to the delayed appearance of the movement disorder. Movement disorders after severe head injury have been reported in 13 to 66% of patients. Although movement disorders after mild or moderate head injury are frequently transient and, in general, do not result in additional disability, kinetic tremors and dystonia may be a source of marked disability in survivors of severe head injury. Functional stereotactic surgery provides long-term symptomatic and functional benefits in the majority of patients. Thalamic radiofrequency lesioning, although beneficial in some patients, frequently is associated with side effects such as increased dysarthria or gait disturbance, particularly in patients with kinetic tremor secondary to diffuse axonal injury. Deep brain stimulation is used increasingly as an option in such patients. It remains unclear whether pallidal or thalamic targets are more beneficial for treatment of posttraumatic dystonia. Trauma to the central nervous system is an important causative factor in a variety of movement disorders. The mediation of the effects of trauma and the pathophysiology of the development of posttraumatic movement disorders require further study. Functional stereotactic surgery should be considered in patients with disabling movement disorders refractory to medical treatment.