Introduction
Although generalized dystonia is of genetic origin in the majority of cases, thus not idiopathic. Generalized dystonia has a reduced quality of life compared to healthy individuals. The reasons are not limited to the clinical characteristics of dystonia but include demographic and social variables and non-muscle movement-related symptoms. Innately, the stigma attached to generalized dystonia requires significant social transformation and coping mechanisms for affected individuals, impacting their quality of life.
What Is Idiopathic Generalized Dystonia?
Generalized dystonia is characterized by involuntary muscle contractions causing slow, repetitive moves or abnormal postures. These movements can be painful, and some individuals with generalized dystonia may harbor tremors or other neurological symptoms. In generalized idiopathic dystonia, there is the involvement of the trunk, legs, and other body parts with no clear identifiable cause and absence of any structural damage or degeneration of the brain.
What Are the Types of Generalized Dystonia?
Dystonia may develop at any age, although earlier onset is more likely to form a severe course. Types of dystonia according to age are as below;
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Early Onset:
Less than 26 years of age.
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Late Onset:
More than 26 years of age.
What Are the Criteria for Generalized Idiopathic Dystonia?
The present criteria for this condition are based on the following;
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A disorder that included dystonic postures and movements. It does not include isolated focal dystonias such as writer’s cramp, cephalic dystonia, or spasmodic torticollis.
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An unremarkable presence at birth or early development period.
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Before the condition's onset, no history of drug exposure or illness associated with dystonia.
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Absence of any intellectual abnormality.
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Negative results for other diseases that can cause dystonia, such as CT (computed tomography) or MRI (magnetic resonance imaging), brain scans, and studies of copper metabolism.
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Absence of other recognizable disorders that may cause dystonia.
What Are the Symptoms of Generalized Idiopathic Dystonia?
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Foot cramp or an inclination for one foot to turn or drag. It can happen periodically or after running or walking.
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Worsening of handwriting after writing a few lines.
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The neck may flex or pull involuntarily, especially when an individual is tired or stressed.
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Both eyes may blink rapidly and uncontrollably. Sometimes spasms may cause the eyes to close.
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Difficulty speaking.
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Subtle facial spasms.
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Difficulty in chewing.
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Eye irritation and excessive sensitivity to bright light.
Dystonia is variable in its advancement. The disease steadily worsens for some individuals, and for others, it rapidly progresses. For some, it may stabilize at a relatively minor stage and not progress further. While for some individuals, it may reach the advanced stage comprising of rapid and involuntary rhythmic moves, twisting postures, distortions of the torso, irregular gait, and eventually, fixed postural deformities.
The disorder is generally not associated with pain but may cause pain in affected areas. For example, cervical dystonia can be painful because of nerve root irritation, spine degeneration, or frequent headaches. In addition, uncontrolled muscle movements can lead to joint deterioration, possibly resulting in the onset of arthritis.
How Is Generalized Idiopathic Dystonia Diagnosed?
The clinician will take the full history and will perform a careful examination.in most cases, the recognition of generalized dystonia is based on clinical features.
Electromyogram (EMG) Mapping:
It can detect the coactivation of agonist and antagonist muscles, the effect of gestures, and the presence of phasic and tonic elements of the movements. EMG mapping is also useful for differentiating dystonic tremors from other tremors.
What Treatments Are Available for Generalized Idiopathic Dystonia?
Currently, there are no medicines to prevent dystonia or restrict its progression. However, several treatment options can ease some symptoms of dystonia, so clinicians may select a therapeutic strategy based on each individual’s symptoms and need.
Botulinum Toxin:
Botulinum injections are often the most effective treatment for dystonias. Injections of small amounts of botulinum chemical into affected muscles stop muscle contractions and can temporarily improve the abnormal postures and motions that characterize dystonia. The toxin reduces muscle spasms by blocking the release of the neurotransmitter acetylcholine, which is responsible for causing muscle contraction normally. The effect typically takes a few days after the injection administration and can last for a few months before the injections need to be repeated. However, the course of the treatment can vary among individuals.
Medications:
Several groups of drugs that have effects on different neurotransmitters may be helpful and effective for various forms of dystonia. These medications are off-label as they are approved by FDA (The U.S. Food and Drug Administration) to treat other disorders or conditions but are not specifically approved as a treatment for dystonia. The response to these drugs varies among individuals and also in the same individual over time. Some of these drugs include the followings;
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Anticholinergic Agents:
Block neurotransmitter acetylcholine effects include Trihexyphenidyl and Benztropine. Occasionally, these drugs can sedate or cause memory difficulties, especially at higher doses and in older individuals. Some common side effects include dry mouth and constipation.
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GABAergic Agents:
These drugs regulate the neurotransmitter GABA. They include the benzodiazepines such as Lorazepam, Diazepam, Clonazepam, and Baclofen. Their common side effect is drowsiness.
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Dopaminergic Agents:
They act on the neurotransmitter dopamine and the dopamine system, which enables the control of muscle movement. Some individuals benefit from drugs like Tetrabenazine that block the effects of dopamine. However, common side effects such as weight gain, involuntary and repetitious muscle movements, and depression can limit the use of these medications.
Deep Brain Stimulation (DBS):
It may be recommended for some people with generalized dystonia, especially where medications do not adequately ease symptoms or intolerable side effects are present. DBS comprises surgically implanting small electrodes which connect to a pulse generator in specific brain areas that control movement. Regulated amounts of electricity are transmitted into the exact parts of the brain that generates dystonic movements and interfere with and intercept the electrical signals that can cause the symptoms. DBS also implicates follow-up and adjustments of settings for optimizing an individual’s DBS.
Other Surgeries:
Some surgeries aim to block pathways responsible for abnormal muscle movements at different levels of the nervous system. Some procedures purposely damage small territories of the thalamus (thalamotomy), some parts of the globus pallidus (pallidotomy), or other deep centers of the brain. At the same time, other surgeries include clipping nerves leading to the nerve roots located deep in the neck near the spinal cord, called anterior cervical rhizotomy, or removing the nerves at the juncture where they enter the contracting muscle, called selective peripheral denervation. Report from a few individuals establishes significant symptoms subsiding after surgery.
Physical and Other Therapies:
They can be helpful as an adjunct to other therapeutic methods. Speech therapy and voice therapy help in the case of spasmodic dysphonia and speech problems. Physical therapy includes splints, biofeedback, and stress management and may help individuals with generalized idiopathic dystonia.
Conclusion
Generalized idiopathic dystonia generally develops gradually, with localized symptoms indicating the presence of the disorder. There is no definitive cure for dystonia. Therefore, its management is mostly directed at relieving symptoms. Surgical treatment such as DBS is considered if medicines and other treatment modalities cannot provide adequate relief and dystonic symptoms negatively affect the quality of life.
