Dystonia is a neurological movement disorder syndrome in which sustained or repetitive muscle contractions result in twisting and repetitive movements or abnormal fixed postures. The movements may resemble a tremor. Dystonia is often intensified or exacerbated by physical activity, and symptoms may progress into adjacent muscles.
The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning (e.g., lead poisoning) or reaction to pharmaceutical drugs, particularly neuroleptics, or stress. Treatment must be highly customized to the needs of the individual and may include oral medications, chemodenervation botulinum neurotoxin injections, physical therapy, or other supportive therapies, and surgical procedures such as deep brain stimulation.
|A person with medication-induced dystonia.|
There are multiple types of dystonia, and many diseases and conditions may cause dystonia.
Dystonia is classified by
Physicians use these classifications to guide diagnosis and treatment.
For example, dystonia musculorum deformans (Oppenhiem, Flatau-Sterling syndrome):
Also known as torsion dystonia or idiopathic torsion dystonia (old terminology "dystonia musculorum deformans").
These most common dystonias are typically classified as follows:
|Anismus||muscles of the rectum||Causes painful defecation, constipation; may be complicated by encopresis.|
|Cervical dystonia (spasmodic torticollis)||muscles of the neck||Causes the head to rotate to one side, to pull down towards the chest, or back, or a combination of these postures.|
|Blepharospasm||muscles around the eyes||The sufferer experiences rapid blinking of the eyes or even their forced closure causing functional blindness.|
|Oculogyric crisis||muscles of eyes and head||An extreme and sustained (usually) upward deviation of the eyes often with convergence causing diplopia(double vision). It is frequently associated with backward and lateral flexion of the neck and either widely opened mouth or jaw clenching. Frequently a result of antiemetics such as the neuroleptics (e.g., prochlorperazine) or metoclopramide. Can be caused by Chlorpromazine.|
|Oromandibular dystonia||muscles of the jaw and muscles of tongue||Causes distortions of the mouth and tongue.|
|Spasmodic dysphonia/Laryngeal dystonia||muscles of larynx||Causes the voice to sound broken, become hoarse, sometimes reducing it to a whisper.|
|Focal hand dystonia (also known as musician's or writer's cramp).||single muscle or small group of muscles in the hand||It interferes with activities such as writing or playing a musical instrument by causing involuntary muscular contractions. The condition is sometimes "task-specific," meaning that it is generally apparent during only certain activities. Focal hand dystonia is neurological in origin and is not due to normal fatigue. The loss of precise muscle control and continuous unintentional movement results in painful cramping and abnormal positioning that makes continued use of the affected body parts impossible.|
Segmental dystonias affect two adjoining parts of the body:
|DYT1||128100||TOR1A||9q34||Early-onset torsion dystonia|
|DYT2||224500||HPCA||1p35-p34.2||Autosomal recessive primary isolated dystonia|
|DYT4||128101||TUBB4||19p13.12-13||Autosomal dominant whispering dysphonia|
|DYT5a||128230||GCH1||14q22.1-q22.2||Autosomal dominant dopamine-responsive dystonia|
|DYT5b||191290||TH||11p15.5||Autosomal recessive dopamine-responsive dystonia|
|DYT6||602629||THAP1||8p11.21||Autosomal dominant dystonia with cranio-cervical predilection|
|DYT7||602124||unknown||18p (questionable)||Autosomal dominant primary focal cervical dystonia|
|DYT8||118800||MR1||2q35||Paroxysmal nonkinesigenic dyskinesia|
|DYT9||601042||SLC2A1||1p35-p31.3||Episodic choreoathetosis/spasticity (now known to be synonymous with DYT18)|
|DYT10||128200||PRRT2||16p11.2-q12.1||Paroxysmal kinesigenic dyskinesia|
|DYT12||128235||ATP1A3||19q12-q13.2||Rapid onset dystonia parkinsonism and alternating hemiplegia of childhood|
|DYT13||607671||unknown, near D1S2667||1p36.32-p36.13||Autosomal dominant cranio-cervical/upper limb dystonia in one Italian family|
|DYT15||607488||unknown||18p11||Myoclonic dystonia not linked to SGCE mutations|
|DYT16||612067||PRKRA||2q31.3||Autosomal recessive young onset dystonia parkinsonism|
|DYT17||612406||unknown, near D20S107||20p11.2-q13.12||Autosomal recessive dystonia in one family|
|DYT18||612126||SLC2A1||1p35-p31.3||Paroxysmal exercise-induced dyskinesia|
|DYT19||611031||probably PRRT2||16q13-q22.1||Episodic kinesigenic dyskinesia 2, probably synonymous with DYT10|
|DYT20||611147||unknown||2q31||Paroxysmal nonkinesigenic dyskinesia 2|
|DYT21||614588||unknown||2q14.3-q21.3||Late-onset torsion dystonia|
|DYT24||610110||ANO3||11p14.2||Autosomal dominant cranio-cervical dystonia with prominent tremor|
There is a group called myoclonic dystonia where some cases are hereditary and have been associated with a missense mutation in the dopamine-D2 receptor. Some of these cases have responded well to alcohol.
Symptoms vary according to the kind of dystonia involved. In most cases, dystonia tends to lead to abnormal posturing, in particular on movement. Many sufferers have continuous pain, cramping, and relentless muscle spasms due to involuntary muscle movements. Other motor symptoms are possible including lip smacking.
Early symptoms may include loss of precision muscle coordination (sometimes first manifested in declining penmanship, frequent small injuries to the hands, and dropped items), cramping pain with sustained use, and trembling. Significant muscle pain and cramping may result from very minor exertions like holding a book and turning pages. It may become difficult to find a comfortable position for arms and legs with even the minor exertions associated with holding arms crossed causing significant pain similar to restless leg syndrome. Affected persons may notice trembling in the diaphragm while breathing, or the need to place hands in pockets, under legs while sitting or under pillows while sleeping to keep them still and to reduce pain. Trembling in the jaw may be felt and heard while lying down, and the constant movement to avoid pain may result in the grinding and wearing down of teeth, or symptoms similar to temporomandibular joint disorder. The voice may crack frequently or become harsh, triggering frequent throat clearing. Swallowing can become difficult and accompanied by painful cramping.
Electrical sensors (EMG) inserted into affected muscle groups, while painful, can provide a definitive diagnosis by showing pulsating nerve signals being transmitted to the muscles even when they are at rest. The brain appears to signal portions of fibers within the affected muscle groups at a firing speed of about 10 Hz causing them to pulsate, tremble and contort. When called upon to perform an intentional activity, the muscles fatigue very quickly and some portions of the muscle groups do not respond (causing weakness) while other portions over-respond or become rigid (causing micro-tears under load). The symptoms worsen significantly with use, especially in the case of focal dystonia, and a "mirror effect" is often observed in other body parts: Use of the right hand may cause pain and cramping in that hand as well as in the other hand and legs that were not being used. Stress, anxiety, lack of sleep, sustained use and cold temperatures can worsen symptoms.
Direct symptoms may be accompanied by secondary effects of the continuous muscle and brain activity, including disturbed sleep patterns, exhaustion, mood swings, mental stress, difficulty concentrating, blurred vision, digestive problems, and short temper. People with dystonia may also become depressed and find great difficulty adapting their activities and livelihood to a progressing disability. Side-effects from treatment and medications can also present challenges in normal activities.
In some cases, symptoms may progress and then plateau for years, or stop progressing entirely. The progression may be delayed by treatment or adaptive lifestyle changes, while forced continued use may make symptoms progress more rapidly. In others, the symptoms may progress to total disability, making some of the more risky forms of treatment worth considering. In some cases with patients who already have dystonia, a subsequent tramatic injury or the effects of general anethesia during an unrelated surgery can cause the symptoms to progress rapidly.
An accurate diagnosis may be difficult because of the way the disorder manifests itself. Sufferers may be diagnosed as having similar and perhaps related disorders including Parkinson's disease, essential tremor, carpal tunnel syndrome, TMD, Tourette's syndrome, conversion disorder or other neuromuscular movement disorders. It has been found that the prevalence of dystonia is high in individuals with Huntington's disease, where the most common clinical presentations are internal shoulder rotation, sustained fist clenching, knee flexion, and foot inversion. Risk factors for increased dystonia in patients with Huntington's disease include long disease duration and use of antidopaminergic medication.
Primary dystonia is suspected when the dystonia is the only sign and there is no identifiable cause or structural abnormality in the central nervous system. Researchers suspect it is caused by a pathology of the central nervous system, likely originating in those parts of the brain concerned with motor function—such as the basal ganglia and the GABA (gamma-aminobutyric acid) producing Purkinje neurons. The precise cause of primary dystonia is unknown. In many cases it may involve some genetic predisposition towards the disorder combined with environmental conditions.
Meningitis and encephalitis caused by viral, bacterial, and fungal infections of the brain have been associated with dystonia. The main mechanism is inflammation of the blood vessels, causing restriction of blood flow to the basal ganglia. Other mechanisms include direct nerve injury by the organism or a toxin, or autoimmune mechanisms.
Environmental and task-related factors are suspected to trigger the development of focal dystonias because they appear disproportionately in individuals who perform high precision hand movements such as musicians, engineers, architects, and artists. Chlorpromazine can also cause dystonia, which can be often misjudged as a seizure. Neuroleptic drugs often cause dystonia, including oculogyric crisis.
Misfunction of the sodium-potassium pump may be a factor in some dystonias. The Na+
pump has been shown to control and set the intrinsic activity mode of cerebellar Purkinje neurons. This suggests that the pump might not simply be a homeostatic, "housekeeping" molecule for ionic gradients; but could be a computational element in the cerebellum and the brain. Indeed, an ouabain block of Na+
pumps in the cerebellum of a live mouse results in it displaying ataxia and dystonia. Ataxia is observed for lower ouabain concentrations, dystonia is observed at higher ouabain concentrations. A mutation in the Na+
pump (ATP1A3 gene) can cause rapid onset dystonia parkinsonism. The parkinsonism aspect of this disease may be attributable to malfunctioning Na+
pumps in the basal ganglia; the dystonia aspect may be attributable to malfunctioning Na+
pumps in the cerebellum (that act to corrupt its input to the basal ganglia) possibly in Purkinje neurons.
Cerebellum issues causing dystonia is described by Filip et al. 2013: "Although dystonia has traditionally been regarded as a basal ganglia dysfunction, recent provocative evidence has emerged of cerebellar involvement in the pathophysiology of this enigmatic disease. It has been suggested that the cerebellum plays an important role in dystonia etiology, from neuroanatomical research of complex networks showing that the cerebellum is connected to a wide range of other central nervous system structures involved in movement control to animal models indicating that signs of dystonia are due to cerebellum dysfunction and completely disappear after cerebellectomy, and finally to clinical observations in secondary dystonia patients with various types of cerebellar lesions. It is proposed that dystonia is a large-scale dysfunction, involving not only cortico-basal ganglia-thalamo-cortical pathways, but the cortico-ponto-cerebello-thalamo-cortical loop as well. Even in the absence of traditional "cerebellar signs" in most dystonia patients, there are more subtle indications of cerebellar dysfunction. It is clear that as long as the cerebellum's role in dystonia genesis remains unexamined, it will be difficult to significantly improve the current standards of dystonia treatment or to provide curative treatment."
Reducing the types of movements that trigger or worsen dystonic symptoms provides some relief, as does reducing stress, getting plenty of rest, moderate exercise, and relaxation techniques. Various treatments focus on sedating brain functions or blocking nerve communications with the muscles via drugs, neuro-suppression, or denervation. All current treatments have negative side-effects and risks. A geste antagoniste is a physical gesture or position (such as touching one's chin) that temporarily interrupts dystonia, it is also known as a sensory trick. Patients may be aware of the presence of a geste antagoniste that provides some relief. Therapy for dystonia can involve prosthetics that passively simulate the stimulation.
While research in the area of effectiveness of physical therapy intervention for dystonia remains weak, there is reason to believe that rehabilitation can benefit dystonia patients. Physical therapy can be utilized to manage changes in balance, mobility and overall function that occur as a result of the disorder. A variety of treatment strategies can be employed to address the unique needs of each individual. Potential treatment interventions include splinting, therapeutic exercise, manual stretching, soft tissue and joint mobilization, postural training and bracing, neuromuscular electrical stimulation, constraint-induced movement therapy, activity and environmental modification, and gait training.
A patient with dystonia may have significant challenges in activities of daily living (ADL), an area especially suited for treatment by occupational therapy (OT). An occupational therapist (OT) may perform needed upper extremity splinting, provide movement inhibitory techniques, train fine motor coordination, provide an assistive device, or teach alternative methods of activity performance to achieve a patient's goals for bathing, dressing, toileting, and other valued activities.
Recent research has investigated further into the role of physiotherapy in the treatment of dystonia. A recent study showed that reducing psychological stress, in conjunction with exercise, is beneficial for reducing truncal dystonia in patients with Parkinson’s Disease. Another study emphasized progressive relaxation, isometric muscle endurance, dynamic strength, coordination, balance, and body perception, seeing significant improvements to patients’ quality of life after 4 weeks.
Since the root of the problem is neurological, doctors have explored sensorimotor retraining activities to enable the brain to "rewire" itself and eliminate dystonic movements. The work of several doctors such as Nancy Byl and Joaquin Farias has shown that sensorimotor retraining activities and proprioceptive stimulation can induce neuroplasticity, making it possible for patients to recover substantial function that was lost due to Cervical Dystonia, hand dystonia, blepharospasm, oromandibular dystonia, dysphonia and musicians' dystonia.
Some focal dystonias have been proven treatable through movement retraining in the Taubman approach, particularly in the case of musicians. However other focal dystonias may not respond and may even be made worse by this treatment.
Due to the rare and variable nature of dystonia, research investigating the effectiveness of these treatments is limited. There is no gold standard for physiotherapy rehabilitation. To date, focal cervical dystonia has received the most research attention; however, study designs are poorly controlled and limited to small sample sizes.
Different medications are tried in an effort to find a combination that is effective for a specific person. Not all people respond well to the same medications. Medications that have had positive results in some include: diphenhydramine, benzatropine and atropine. anti-Parkinsons agents (such as ropinirole and bromocriptine), and muscle relaxants (such as diazepam).
Medications such as anticholinergics (benztropine), which act as inhibitors of the neurotransmitter acetylcholine, may provide some relief. In the case of an acute dystonic reaction, diphenhydramine is sometimes used (though this drug is well known as an antihistamine, in this context it is being used primarily for its anticholinergic role).. See also Procyclidine.
A baclofen pump has been used to treat patients of all ages exhibiting muscle spasticity along with dystonia. The pump delivers baclofen via a catheter to the thecal space surrounding the spinal cord. The pump itself is placed in the abdomen. It can be refilled periodically by access through the skin. Baclofen can also be taken in tablet form
Botulinum toxin injections into affected muscles have proved quite successful in providing some relief for around 3–6 months, depending on the kind of dystonia. Botox or Dysport injections have the advantage of ready availability (the same form is used for cosmetic surgery) and the effects are not permanent. There is a risk of temporary paralysis of the muscles being injected or the leaking of the toxin into adjacent muscle groups, causing weakness or paralysis in them. The injections must be repeated, as the effects wear off and around 15% of recipients develop immunity to the toxin. There is a Type A and a Type B toxin approved for treatment of dystonia; often, those that develop resistance to Type A may be able to use Type B.
Clonazepam, an anti-seizure medicine, is also sometimes prescribed. However, for most, their effects are limited and side-effects like mental confusion, sedation, mood swings, and short-term memory loss occur.
Dopamine agonists: One type of dystonia, dopamine-responsive dystonia, can be completely treated with regular doses of L-DOPA in a form such as Sinemet (carbidopa/levodopa). Although this does not remove the condition, it does alleviate the symptoms most of the time. (In contrast, dopamine antagonists can sometimes cause dystonia.)
A Ketogenic diet consisting of 70% fats (focusing on medium chain triglycerides and unsaturated fats), 20% protein and 10% carbohydrates (any sugar) has shown strong promise as a treatment for Dystonia. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270868/]
Surgery, such as the denervation of selected muscles, may also provide some relief; however, the destruction of nerves in the limbs or brain is not reversible and should be considered only in the most extreme cases. Recently, the procedure of deep brain stimulation (DBS) has proven successful in a number of cases of severe generalised dystonia. DBS as treatment for medication-refractory dystonia, on the other hand, may increase the risk of suicide in patients. However, reference data of patients without DBS therapy are lacking.
The Italian Bernardino Ramazzini provided one of the first descriptions of task-specific dystonia in 1713 in a book of occupational diseases, The Morbis Artificum. In chapter II of this book’s Supplementum, Ramazzini noted that “Scribes and Notaries” may develop “incessant movement of the hand, always in the same direction … the continuous and almost tonic strain on the muscles... that results in failure of power in the right hand.” A report from the British Civil Service also contained an early description of writer’s cramp. In 1864, Solly coined the term “scrivener’s palsy” for this affliction. These historical reports usually attributed the etiology of the motor abnormalities to overuse. Then, dystonia were reported in detail in 1911, when Hermann Oppenheim, Edward Flatau and Wladyslaw Sterling described some Jewish children affected by a syndrome that was retrospectively considered to represent familial cases of DYT1 dystonia. Some decades later, in 1975, the first international conference on dystonia was held in New York. It was then recognized that, in addition to severe generalized forms, the dystonia phenotype also encompasses poorly-progressive focal and segmental cases with onset in adulthood, such as blepharospasm, torticollis and writer’s cramp. These forms were previously considered independent disorders and were mainly classified among neuroses. A modern definition of dystonia was worded some years later, in 1984. During the following years it became evident that dystonia syndromes are numerous and diversified, new terminological descriptors (e.g., dystonia plus, heredodegenerative dystonias, etc.) and additional classification schemes were introduced. The clinical complexity of dystonia was then fully recognized.
Basal ganglia disease is a group of physical problems that occur when the group of nuclei in the brain known as the basal ganglia fail to properly suppress unwanted movements or to properly prime upper motor neuron circuits to initiate motor function. Research indicates that increased output of the basal ganglia inhibits thalamocortical projection neurons. Proper activation or deactivation of these neurons is an integral component for proper movement. If something causes too much basal ganglia output, then the Ventral Anterior (VA) and Ventral Lateral (VL) thalamocortical projection neurons become too inhibited and one cannot initiate voluntary movement. These disorders are known as hypokinetic disorders. However, a disorder leading to abnormally low output of the basal ganglia leads to relatively no inhibition, and thus excitation, of the thalamocortical projection neurons (VA and VL) which synapse onto the cortex. This situation leads to an inability to suppress unwanted movements. These disorders are known as hyperkinetic disorders. Currently, reasons for abnormal increases or decreases of basal ganglia output are poorly understood. One possible factor could be the natural accumulation of iron in the basal ganglia, causing neurodegeneration due to its involvement in toxic, free-radical reactions. Though motor disorders are the most common associated with the basal ganglia, recent research shows that basal ganglia disorders can lead to other dysfunctions such as obsessive compulsive disorder (OCD) and Tourette syndrome.Blepharospasm
Blepharospasm is any abnormal contraction or twitch of the eyelid. The condition should be distinguished from the more common, and milder, involuntary quivering of an eyelid, known as myokymia. In most cases, blepharospasm symptoms last for a few days and then disappear without treatment, but in some cases the twitching is chronic and persistent, causing life-long challenges. In these cases, the symptoms are often severe enough to result in functional blindness. The person's eyelids feel like they are clamping shut and will not open without great effort. People have normal eyes, but for periods of time are effectively blind due to their inability to open their eyelids. In contrast, the reflex blepharospasm is due to any pain in and around the eye.
It is of two types: essential and reflex blepharospasm. The benign essential blepharospasm is a focal dystonia—a neurological movement disorder involving involuntary and sustained contractions of the muscles around the eyes. The term essential indicates that the cause is unknown, but fatigue, stress, or an irritant are possible contributing factors. Blepharospasm is sometimes part of benign fasciculation syndrome.
Although there is no cure, botulinum toxin injections may help temporarily. A surgical procedure known as myectomy may also be useful. It is a fairly rare disease, affecting only one in every 20,000 people in the United States. The word is from Greek: βλέφαρον / blepharon, eyelid, and σπασμός / spasmos, spasm, an uncontrolled muscle contraction.D-DOPA
D-DOPA (D-3,4-dihydroxyphenylalanine; dextrodopa) is similar to L-DOPA (levodopa), but with opposite chirality. Levo- and dextro- rotation refer to a molecule's ability to rotate planes of polarized light in either direction. Whereas L-DOPA is moderately effective in the treatment of Parkinson's disease (PD) and Dopamine-responsive dystonia (DRD) by stimulating the production of dopamine in the brain, D-DOPA is biologically inactive.Dysautonomia
Dysautonomia or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic. A number of conditions can feature dysautonomia, such as Parkinson's disease, HIV/AIDS, multiple system atrophy, autonomic failure, postural orthostatic tachycardia syndrome, and autonomic neuropathy.The diagnosis is achieved through functional testing of the ANS, focusing on the affected organ system. Investigations may be performed to identify underlying disease processes that may have led to the development of symptoms or autonomic neuropathy. Symptomatic treatment is available for many symptoms associated with dysautonomia, and some disease processes can be directly treated.Dyskinesia
Dyskinesia refers to a category of movement disorders that are characterized by involuntary muscle movements, including movements similar to tics or chorea and diminished voluntary movements. Dyskinesia can be anything from a slight tremor of the hands to an uncontrollable movement of the upper body or lower extremities. Discoordination can also occur internally especially with the respiratory muscles and it often goes unrecognized. Dyskinesia is a symptom of several medical disorders that are distinguished by their underlying cause.Focal dystonia
Focal dystonia is a neurological condition, a type of dystonia, that affects a muscle or group of muscles in a specific part of the body, causing involuntary muscular contractions and abnormal postures. For example, in focal hand dystonia, the fingers either curl into the palm or extend outward without control. In musicians, the condition is called musician's focal dystonia, or simply, musician's dystonia. In sports, it is commonly referred to as the yips.Hyperkinesia
Hyperkinesia refers to an increase in muscular activity that can result in excessive abnormal movements, excessive normal movements, or a combination of both. Hyperkinesia is a state of excessive restlessness which is featured in a large variety of disorders that affect the ability to control motor movement, such as Huntington's disease. It is the opposite of hypokinesia, which refers to decreased bodily movement, as commonly manifested in Parkinson's disease. Many hyperkinetic movements are the result of improper regulation of the basal ganglia-thalamocortical circuitry. Overactivity of a direct pathway combined with decreased activity of an indirect pathway results in activation of thalamic neurons and excitation of cortical neurons, resulting in increased motor output. Often, hyperkinesia is paired with hypotonia, a decrease in muscle tone. Many hyperkinetic disorders are psychological in nature and are typically prominent in childhood. Depending on the specific type of hyperkinetic movement, there are different treatment options available to minimize the symptoms, including different medical and surgical therapies. The word hyperkinesis comes from the Greek hyper, meaning "increased," and kinein, meaning "to move."Meige's syndrome
Meige's syndrome is a type of dystonia. It is also known as Brueghel's syndrome and oral facial dystonia. It is actually a combination of two forms of dystonia, blepharospasm and oromandibular dystonia (OMD).
When OMD is combined with blepharospasm, it may be referred to as Meige’s Syndrome named after Henri Meige, the French neurologist who first described the symptoms in detail in 1910. The symptoms usually begin between the ages of 30 and 70 years old and appear to be more common in women than in men (2:1 ratio). The combination of upper and lower dystonia is sometimes called cranial-cervical dystonia. The incidence is about one case in 20,000 people.Mohr–Tranebjærg syndrome
Mohr–Tranebjærg syndrome (MTS) is a rare X-liked recessive syndrome also known as deafness–dystonia syndrome and caused by mutation in the TIMM8A gene. It was first described in 1960. The severity of the symptoms may vary, but they progress usually to severe deafness and dystonia and sometimes are accompanied by cortical deterioration of vision and mental deterioration.Myoclonic dystonia
Myoclonic dystonia or Myoclonus dystonia syndrome is a rare movement disorder that induces spontaneous muscle contraction causing abnormal posture. The prevalence of myoclonus dystonia has not been reported, however, this disorder falls under the umbrella of movement disorders which affect thousands worldwide. Myoclonus dystonia results from mutations in the SGCE gene coding for an integral membrane protein found in both neurons and muscle fibers. Those suffering from this disease exhibit symptoms of rapid, jerky movements of the upper limbs (myoclonus), as well as distortion of the body's orientation due to simultaneous activation of agonist and antagonist muscles (dystonia).
Myoclonus dystonia is caused by loss-of-function-mutations in the epsilon sarcoglycan gene (SGCE). The disease is dominantly inherited, however SGCE is an imprinted gene, so only the paternal allele is expressed. Therefore, children suffering from this disease inherit the mutation from the father. If the mutated allele is inherited from the mother, the child is not likely to exhibit symptoms.
While no cure has been found for myoclonus dystonia, treatment options are available to those suffering from the disease. Ethanol often ameliorates the symptoms well, and so the syndrome is also called "Alcohol-responsive dystonia". Alcohol may be substituted by benzodiazepines, such as clonazepam, which work through the same mechanism. Deep brain stimulation (DBS) is another viable option that can alleviate symptoms without the unwanted side effects of medications, and has been successful in treating other movement disorders.Procyclidine
Procyclidine is an anticholinergic drug principally used for the treatment of drug-induced parkinsonism, akathisia and acute dystonia; Parkinson disease; and idiopathic or secondary dystonia.SGCE
Epsilon-sarcoglycan is a protein that in humans is encoded by the SGCE gene.The SGCE gene encodes the epsilon member of the sarcoglycan family, transmembrane components of the dystrophin-glycoprotein complex, which links the cytoskeleton to the extracellular matrix.[supplied by OMIM]Spasm
A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ such as the heart.
A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a muscle cramp which is accompanied by a sudden burst of pain. A muscle cramp is usually harmless and ceases after a few minutes. It is typically caused by ion imbalance or muscle overload.
There are other causes of involuntary muscle contractions, and some of these may cause a health problem.Spasmodic dysphonia
Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm. This results in breaks or interruptions in the voice, often every few sentences, which can make a person difficult to understand. The person's voice may also sound strained or they may be nearly unable to speak. Onset is often gradual and the condition is lifelong.The cause is unknown. Risk factors may include family history. Triggers may include an upper respiratory infection, injury to the larynx, overuse of the voice, and psychological stress. The underlying mechanism is believed to typically involve the central nervous system, specifically the basal ganglia. Diagnosis is typically made following examination by a team of healthcare providers. It is a type of focal dystonia.While there is no cure, treatment may improve symptoms. Most commonly this involves injecting botulinum toxin into the affected muscles of the larynx. This generally results in improvement for a few months. Other measures include voice therapy, counselling, and amplification devices. If this is not effective, surgery may be considered; however, evidence to support surgery is limited.The disorder affects an estimated 2 per 100,000 people. Women are more commonly affected. Onset is typically between the ages of 30 and 50. Severity is variable between people. In some, work and social life are affected. Life expectancy is, however, normal.Spasmodic torticollis
Spasmodic torticollis is an extremely painful chronic neurological movement disorder causing the neck to involuntarily turn to the left, right, upwards, and/or downwards. The condition is also referred to as "cervical dystonia". Both agonist and antagonist muscles contract simultaneously during dystonic movement.
Causes of the disorder are predominantly idiopathic. A small number of patients develop the disorder as a result of another disorder or disease. Most patients first experience symptoms midlife. The most common treatment for spasmodic torticollis is the use of botulinum toxin type A.Status dystonicus
Status dystonicus is a serious and potentially life-threatening disorder which occurs in people who have primary or secondary dystonia. Symptoms consist of widespread severe muscle contractions. Treatment can be difficult but status dystonicus may respond to midazolam, propofol, baclofen and bilateral pallidal deep brain stimulation.TIMM8A
Mitochondrial import inner membrane translocase subunit Tim8 A, also known as Deafness-dystonia peptide or protein is an enzyme that in humans is encoded by the TIMM8A gene. This translocase has similarity to yeast mitochondrial proteins that are involved in the import of metabolite transporters from the cytoplasm into the mitochondrial inner membrane. The gene is mutated in Deafness-dystonia syndrome (or Mohr-Tranebjaerg syndrome; MTS/DFN-1) and it is postulated that MTS/DFN-1 is a mitochondrial disease caused by a defective mitochondrial protein import system.Tardive dyskinesia
Tardive dyskinesia (TD) is a disorder that results in involuntary, repetitive body movements. This may include grimacing, sticking out the tongue, or smacking the lips. Additionally there may be rapid jerking movements or slow writhing movements. In about 20% of people, decreased functioning results.Tardive dyskinesia occurs in some people as a result of long-term use of neuroleptic medications (antipsychotics, metoclopramide). These medications are usually used for mental illness, but may also be given for gastrointestinal or neurological problems. The condition typically develops only after months to years of use. The diagnosis is based on the symptoms after ruling out other potential causes.Efforts to prevent the condition include not using or using the lowest possible dose of neuroleptics. Treatment includes stopping the neuroleptic medication if possible or switching to clozapine. Other medications such as valbenazine, tetrabenazine, or botulinum toxin may be used to lessen the symptoms. With treatment some see a resolution of symptoms while others do not.Rates in those on atypical antipsychotics are about 20%, while those on typical antipsychotics have rates of about 30%. Risk is greater in older people. The term "tardive dyskinesia" first came into use in 1964.Writer's cramp
Writer's cramp, also called mogigraphia and scrivener's palsy, is a disorder caused by cramps or spasms of certain muscles of the hand and/or forearm, and presents itself while performing fine motor tasks, such as writing or playing an instrument. Writer's cramp is a task-specific focal dystonia of the hand. 'Focal' refers to the symptoms being limited to one location (the hand in this case), and 'task-specific' means that symptoms first occur only when the individual engages in a particular activity. Writer's cramp first affects an individual by interfering with their ability to write, especially for prolonged periods of time.