From the Guidelines
Dystonia is caused by a variety of factors, including genetic mutations, brain injuries, certain medications, and other neurological conditions, with the most recent and highest quality evidence suggesting that early identification of the cause is crucial for guiding treatment approaches. The causes of dystonia can be broadly categorized into primary and secondary forms. Primary dystonia results from genetic causes, with mutations in genes like DYT1/TOR1A being well-established culprits 1. Secondary dystonia develops from identifiable causes such as stroke, traumatic brain injury, oxygen deprivation, infections affecting the brain, brain tumors, or as a side effect of medications (particularly antipsychotics like haloperidol) 1. Certain neurodegenerative disorders including Parkinson's disease, Huntington's disease, and Wilson's disease can also trigger dystonia 1.
Some key points to consider when evaluating the causes of dystonia include:
- Genetic mutations: Mutations in genes like DYT1/TOR1A are well-established causes of primary dystonia 1.
- Brain injuries: Stroke, traumatic brain injury, and oxygen deprivation can all contribute to the development of secondary dystonia 1.
- Medications: Certain medications, particularly antipsychotics like haloperidol, can cause dystonia as a side effect 1.
- Neurodegenerative disorders: Conditions like Parkinson's disease, Huntington's disease, and Wilson's disease can all trigger dystonia 1.
The underlying mechanism of dystonia involves dysfunction in the basal ganglia and related brain circuits that control movement, resulting in abnormal muscle contractions and postures. In many cases, especially in adult-onset focal dystonias, the exact cause remains unknown despite extensive investigation, suggesting complex interactions between genetic predisposition and environmental factors. Early identification of the cause is important as it may guide treatment approaches, particularly for secondary forms where addressing the underlying condition might improve dystonia symptoms 1.
From the Research
Causes of Dystonia
The causes of dystonia are multifaceted and can be classified into different categories.
- Primary dystonia: This type of dystonia is characterized by dystonia as the sole phenotypic manifestation, with the exception of tremor 2.
- Secondary dystonia: This type of dystonia is caused by environmental factors, brain injuries, or other medical conditions 3.
- Heredodegenerative diseases with dystonia: These are diseases that cause dystonia as a symptom, along with other neurological symptoms 2.
- Dystonia plus: This category includes diseases that cause dystonia along with other neurological symptoms, such as parkinsonism or myoclonus 2.
Genetic Causes
Genetic mutations can also cause dystonia, with many cases of childhood- and adolescent-onset dystonia being due to mutations in TOR1A and THAP1 2.
- Mutations in THAP1 and CIZ1 have been associated with sporadic and familial adult-onset dystonia 2.
- The genetic basis for most cases of adult-onset primary dystonia is still not well understood 2.
Environmental Causes
Environmental factors can also play a role in the development of dystonia, with some studies suggesting that environmental stressors can act as disease modifiers in dystonia pathogenesis 4.
- Certain environmental factors, such as eye diseases, sore throat, and repetitive upper limb motor action, have been associated with specific forms of primary adult-onset focal dystonia 3.
- There is also evidence to suggest that coffee drinking may have an inverse association with blepharospasm 3.
Pathophysiological Considerations
The pathophysiological substrate of dystonia is related to several lines of research, including loss of inhibition, sensory dysfunction, and alterations of synaptic plasticity 5.
- These abnormalities can lead to the development of dystonia, and may be influenced by both genetic and environmental factors 5.