Dystonia

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There are multiple types of dystonia, and many diseases and conditions may cause dystonia. Dystonia is classified by clinical characteristics such as age of onset, body distribution, nature of the symptoms, and associated features such as additional movement disorders or neurological symptoms. It is also classified by cause, which includes changes or damage to the nervous system and inheritance.^[4] Types include generalized dystonia, focal dystonia, psychogenic dystonia, acute dystonic reaction,^[5] and Vegetative-vascular dystonia.

Generalized dystonias

This section is missing information about other examples/types of generalized dystonia. (May 2025)

For example, in dystonia musculorum deformans (Oppenheim, Flatau-Sterling syndrome), also known as torsion dystonia or idiopathic torsion dystonia, ^[6] the individual has a normal birth history and milestones before a childhood onset. It is autosomal dominant and starts in the lower limbs before spreading upwards.

Symptoms vary according to the kind of dystonia involved. In most cases, dystonia tends to lead to abnormal posturing, in particular on movement. Many individuals with the condition have continuous pain, cramping, and relentless muscle spasms due to involuntary muscle movements. Other motor symptoms are possible including lip smacking.^[16]

An accurate diagnosis may be difficult because of the way the disorder manifests itself. Affected individuals may be diagnosed as having similar and perhaps related disorders including Parkinson's disease, essential tremor, carpal tunnel syndrome, temporomandibular joint disorder, 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.^[17] Risk factors for increased dystonia in patients with Huntington's disease include long disease duration and use of antidopaminergic medication.^[17]

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.^[18]

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.^[19]

Malfunction of the sodium-potassium pump may be a factor in some dystonias. The Na⁺
-K⁺
pump has been shown to control and set the intrinsic activity mode of cerebellar Purkinje neurons.^[20] 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.^[21] Indeed, an ouabain block of Na⁺
-K⁺
pumps in the cerebellum of a live mouse results in it displaying ataxia and dystonia.^[22] Ataxia is observed for lower ouabain concentrations, dystonia is observed at higher ouabain concentrations. A mutation in the Na⁺
-K⁺
pump (ATP1A3 gene) can cause rapid onset dystonia parkinsonism.^[23] The parkinsonism aspect of this disease may be attributable to malfunctioning Na⁺
-K⁺
pumps in the basal ganglia; the dystonia aspect may be attributable to malfunctioning Na⁺
-K⁺
pumps in the cerebellum (that act to corrupt its input to the basal ganglia) possibly in Purkinje neurons.^[20]

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."^[24]

Various treatments focus on sedating brain functions or blocking nerve communications with the muscles via drugs, neuro-suppression, or selective denervation surgery.^[25] Almost all 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.^[26] Patients may be aware of the presence of a geste antagoniste that provides some relief.^[27] Therapy for dystonia can involve prosthetics that passively simulate the stimulation.^[28]

Surgery

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.^[43] 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.^[44]

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.^[45] 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 condition. These historical reports usually attributed the etiology of the motor abnormalities to overuse. Then, dystonia was reported in detail in 1911, when Hermann Oppenheim,^[46] 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.^[47]

• Extrapyramidal symptoms
• Hypertonia
• Sydenham's chorea
• Ulegyria (brain condition with dystonia symptoms)