Hyperkinetic movement disorders (HMDs) or dyskinesias, refer to a group of excessive, abnormal and involuntary movements. There are five major types of HMDs (Table 1).1 Some authors also define ballism separately or as chorea that affects proximal joints.2 Other HMDs include athetosis, stereotypies and in the amputee population “jumpy stumps”.
HMDs can be itself a disease entity or a sign of another underlying neurologic condition. They can result from genetic abnormalities and neurodegenerative diseases; structural lesions; infection; drugs and toxins; or psychogenic causes (Table 2).1,2,3,4,5 However, in many cases they have no clear cause and are thus identified as idiopathic.
Epidemiology including risk factors and primary prevention
Tremor, especially essential tremor (ET), is the most frequent type of HMD seen in clinical practice. An estimated 10-20 million individuals in the United States live with ET.6 Huntington’s Disease is the most frequent cause of chorea with a worldwide prevalence of 3/100,000 people.5 Anywhere from 2-50 children/million develop early-onset dystonia and 30-7,000 adults/million develop late-onset dystonia.7 Adult-onset focal dystonia is by far the most frequent form of isolated dystonia. Focal dystonia is approximately tenfold more common than generalized dystonia. Cervical dystonia is the most frequently documented focal dystonia.7
Psychiatric illnesses and associated neuroleptic medications have been associated with HMD. Therefore, close monitoring of patients on psychiatric medications is warranted for early detection and prevention.
Tremors are associated with brainstem, cerebellum or thalamic lesions. Chorea and ballism have been linked to lesions in the subthalamic nucleus. Dystonia is primarily associated with dysfunction of the putamen or globus pallidus. Myoclonus can be caused by irritation or destruction of gray matter. Tics can involve inflammation or degeneration of the basal ganglia in rare cases.2 Among all HMDs there appears to be decreased neural firing rates in the inhibitory output nuclei of the basal ganglia leading to a subsequent disinhibition of thalamocortical activity. Sensory abnormalities may also have a role.8
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time):
Disease progression amongst HMDs can be highly variable. Huntington’s disease will gradually progress to include dementia, psychiatric disturbance, dysphagia and falls. Tremors associated with Parkinson’s disease usually worsen. Primary dystonia that begins in childhood can start in a single limb but will eventually spread to other body regions.7 Adult-onset primary HMDs are usually non-progressive. Tics generally begin in the head and neck but can progress to the trunk and extremities. Peak tic severity is usually experienced before mid-teens. Tics decrease in severity and may even disappear in adult life in a large proportion of patients. HMDs due to stroke or brain injury are usually static and do not progress if the precipitating factor is no longer active.
Specific secondary or associated conditions and complications
Many patients with HMD suffer from social phobias, depression and anxiety.9,10 Cervical dystonia has been associated with premorbid psychiatric disorders.10 Dementia and dysphagia will develop with Huntington’s disease. Growing and aging with a generalized dystonia can result in joint contractures, chronic pain, nerve compression, spondylosis, vascular compromise and dysphagia.
Essentials of Assessment
Distinguish, based on description of the abnormal movement, if the HMD consists of tremors, jerky or shock like movements, tics or abnormal postures. History of distribution of the movements will help determine if the disorder is focal, multifocal, unilateral or generalized. Finally focus on identification of etiology by assessing age at onset, childhood development, prior infections, exposures, trauma, progression, symptoms, co-morbidities, family history and psychosocial history.
The examiner should pay attention to the character of the movements, pattern of involvement, speed, rhythmicity, duration, suppressibility and triggers. Resting tremor occurs when the extremity is relaxed. Action tremor occurs during attempts to sustain posture (postural tremor) or with movement (kinetic, intention and task-specific tremors). Immediate onset of tremor once the arms are outstretched is characteristic of ET. A dystonic tremor is arrhythmic. Chorea involves the distal extremities in contrast to ballism which involves the shoulder or hip. Patients with dystonia may have a sensory trick (geste antagoniste) which is a physical gesture that temporarily suppresses the movement disorder.
Clinical functional assessment: mobility/self care/cognition/behavior/affective state
Patients should have their gait and balance assessed by clinician and/or therapist with focus on safety and fall prevention. Certain HMDs are best observed during attempts at functional tasks as these disorders may interfere with (instrumented) activities of daily living. Some neurodegenerative HMDs can affect speech, cognition and cause dysphagia. Mental health assessment can identify associated depression, anxiety or social phobias.
Dyskinesias are typically diagnosed clinically. However, underlying metabolic, endocrine, immunologic, infectious and toxic etiologies may be excluded with blood work including thyroid function panel and ceruloplasmin and analysis of cerebrospinal fluid to rule out infectious or autoimmune causes. Paraneoplastic panels and genetic testing may also be pursued in certain cases.
Computerized axial tomography (CAT) scan or magnetic resonance imaging (MRI) may assist with ruling out structural abnormalities. Radiographs, CAT scans or MRI are indicated in cases of suspected cervical or truncal dystonia to rule out structural derangements. Dopamine transporter single-photon emission computed tomography (SPECT) scan also known as DaTscanTM may be useful in discriminating between tremor due ET versus Parkinson’s disease or other Parkinsonian syndromes. DaTScanTM may also be helpful in helping identify dopamine responsive dystonia. Diffusion tensor imaging is emerging as a powerful tool for understanding pathway alterations in movement disorders but is not widely available yet.
Supplemental assessment tools
Electroencephalogram may be used for the work up of chorea and myoclonus to help differentiate whether the abnormal movements are due to abnormal cortical, subcortical, or spinal activity. If available, gait or motion analysis with dynamic surface polyelectromyography recordings can help identify antagonistic muscles to assist with treatment planning, especially if planning to perform targeted chemodenervation with botulinum toxin.
Early prediction of outcomes
Huntington’s disease, a trinucleotide repeat disorder, are often more severe and earlier in onset with increased repeat lengths. Onset of primary dystonia in the leg before the age of 26 increases the risk of developing severe generalized dystonia.14
Tremors can be caused by nicotine, alcohol (and withdrawal), carbon monoxide, lead, mercury, tolulene, dichlorodiphenyltrichlorethane (DDT), naphthalene, manganese, lindane, arsenic, kepone, cyanide and dioxins.2 Psychological stressors can also exacerbate HMDs stressing the importance of a social support system.
Social role and social support system
A social worker can provide patient with information regarding outside resources such as home nursing, home health aide and therapy services when appropriate. Patients should also be given information regarding national and local support groups to help provide education, access to participate in clinical research studies and life management tips.
For certain psychiatric disorders such as schizophrenia, the treatment itself has resulted in the HMD and the question arises whether to continue treatment. Some of these patients are cognitively impaired and institutionalized, therefore informed consent is sometimes not possible. Another ethical consideration is if patients with severe neurodegenerative disorders should have the right to physician assisted suicide.
Rehabilitation Management and Treatments
Available or current treatment guidelines
Oral medications (e.g. anti-epileptics, anticholinergics, dopamine depletors, beta blockers, GABA agonists) primarily act via inhibitory pathways in attempt to suppress abnormal movement except for dopa-responsive dystonia which improves with use of dopaminergics such as levodopa. Certain focal or multifocal movement disorders can be targeted with botulinum toxin injections to reduce activity in antagonist muscles with some success. More severe or generalized HMDs may require neuromodulation with intrathecal baclofen or deep brain stimulation (DBS). For some, relaxation therapies (e.g. yoga, biofeedback) and avoidance of aggravating stimuli (e.g. caffeine, stressors) will also decrease the frequency and severity of tremor, tics and dystonia.
At different disease stages
The potential benefits of exercise in HMDs is well documented not only with improving patients’ strength and endurance but also with improving psychological wellbeing.11 However, no definitive rehabilitation guidelines are available for addressing HMDs though these patients are commonly referred to therapy. Strategies (i.e. use of sensory tricks with dystonia) and adaptive equipment (i.e. weighted utensils and garments for tremor) may be beneficial. Regular stretching may prevent contractures in dystonia. Use of orthotics, assistive devices and wheelchairs may be indicated to enhance mobility and safety.
Oral medications are of variable benefit. Tetrabenazine is approved for Huntington’s disease related chorea. Trihexyphenidyl can be used to treat tremor and dystonia but is poorly tolerated. Pramipexole, beta-blockers, anti-epileptics and benzodiazepines have been used to treat tremors and myoclonus with mixed success. Botulinum toxin injections are useful for focal and multifocal dystonia. Generalized dystonia may benefit from intrathecal baclofen therapy. DBS has shown benefit for multiple HMDs especially essential tremor, tremor due to Parkinson’s disease and primary generalized dystonia.
Secondary prevention of falls, aspiration, infections, malnutrition and pressure sores becomes the primary focus of management. Behavioral interventions may be required. In some severe cases, hospice care should be considered.
Coordination of care
Patients with HMDs may benefit from a coordinated team approach including a neurologist, a physiatrist, therapists and a social worker for ongoing management. In some cases, this team should also include a psychiatrist and/or psychologist to assist with mood and behavioral issues, especially considering some psychiatric medications can exacerbate the HMD.
Patient & family education
Patient and family education is important for identifying symptoms, monitoring treatment response, secondary prevention efforts, goal-setting and management of expectations. Decisions regarding genetic testing (whether for diagnosis or family planning) may be emotionally challenging and can have financial implications. Therefore, inclusion of a genetic counselor in these discussions is advisable.
Measurement of Treatment Outcomes including those that are impairment-based, activity participation-based and environmentally-based
The Unified Huntington’s Disease Rating Scale assesses motor function, cognitive function, behavioral abnormalities and functional capacity associated with Huntington’s disease.12 The Fahn-Tolosa-Marin tremor rating scale was developed to assess essential upper extremity tremor.13 The Toronto Western Spasmodic Torticollis Rating Scale has been used for assessment of cervical dystonia and to demonstrate the benefits of botulinum toxin in clinical trials.14 Several other scales to measure dystonia are available including the Fahn-Marsden Scale, Unified Dystonia Rating Scale and the Global Dystonia Rating Scale.15,16 For practical purposes, patient testimony, clinical assessment and collecting video recordings remain the mainstay of evaluation and assessing treatment.
Translation into Practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
Management of HMDs requires a multidisciplinary and multifaceted approach. Initial treatment initially involves trials with medications to reduce HMD as well as optimization of psychiatric comorbidities sometimes in coordination with psychiatry. In some cases, focal HMDs can be treated with chemodenervation. Assistive devices such as weighted utensils and orthotics should also be considered. Cases unresponsive to conservative treatment may be amenable to neuromodulation with DBS or intrathecal baclofen therapy. Areas for practice improvement involve earlier diagnosis and intervention as oftentimes these patients are often misunderstood and misdiagnosed and therefore can go without formal diagnosis and treatment for years after onset.
Cutting edge/emerging and unique concepts and practice
Advances in neuromodulation and neurosurgery for the treatment of movement disorders continue to evolve.17,18 DBS is being offered as a treatment option for other HMDs such as cerebellar outflow tremor, Holmes tremor, tics due to Tourette syndrome, cervical dystonia, Huntington’s chorea, tardive dyskinesia, myoclonus, and hemiballism with variable outcomes. Intraventricular baclofen therapy is also being investigated in the treatment of generalized dystonia. Magnetic resonance imaging guided focused ultrasound can create lesions in the brain to reduce tremor. Transcranial magnetic stimulation to enhance intracortical inhibition and gene therapy are other approaches to the treatment of HMDs being investigated.
Gaps in the evidence-based knowledge
Psychiatric illness and HMD are commonly associated suggesting the underlying pathophysiology is potentially intertwined. Studies of genetic and biochemical abnormalities and advanced neuroimaging (e.g. DaTscan, functional MRI and diffusion tensor imaging) on these patients may help elucidate the underlying abnormalities to yield more effective treatment strategies for both.
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Original Version of the Topic
Heather R. Ene, MD. Hyperkinetic movement disorders (including dystonias, choreas). Original Publication Date: 09/20/2014
Daniel Moon, MD, MS
Nothing to Disclose
Nicole Ferro, DO
Nothing to Disclose