Dystonias

Dystonia is a movement disorder characterized by involuntary muscle contractions of antagonist muscle groups, leading to repetitive movements and/or abnormal twisting postures. Dystonic movements can be sustained or intermittent and are often accompanied by pain and joint deformity.

This is a very rare and underdiagnosed neurological syndrome, as it is commonly mistaken for other conditions such as tics, Parkinsonian tremor, essential tremor, myoclonus, or psychogenic movement disorders.

Based on their anatomical distribution, the following types of muscular dystonias are classified:

• Focal dystonia: Affects a specific muscle group, mainly in the cranial muscles, neck, larynx, limbs, or trunk. It typically appears in adulthood and is the most prevalent type of dystonia.
• Cervical dystonia or spasmodic torticollis: Contraction of the neck muscles that causes head rotations, tilts, or movements from side to side or up and down. It is the most common focal dystonia.
• Blepharospasm or ocular dystonia: Contraction of the orbicular muscles, leading to involuntary intermittent or sustained eye closure.
• Oromandibular dystonia: Affects the superficial muscles of the neck and lower face, which control the opening and closing of the mouth. It can sometimes include tongue dystonia.
• Laryngeal dystonia or spasmodic dysphonia: Involves contraction of the muscles that regulate the opening and closing of the vocal cords.
• Adductor type: The vocal cords tighten and come together, resulting in a strained, broken voice.
• Abductor type: The vocal cords separate forcefully, producing a whispering voice.
• Occupational dystonias: Occur when performing a specific motor activity, such as writing, playing tennis, or playing a musical instrument.
• Generalized dystonia: Affects most of the body. It typically begins in childhood and is progressive, starting in the lower limbs and spreading to the trunk, neck, and other body regions.
• Segmental dystonia: Affects two or more adjacent anatomical regions, such as a combination of blepharospasm and oromandibular dystonia.
• Multifocal dystonia: Involves two or more distant body areas, such as spasmodic dysphonia and leg dystonia.
• Hemidystonia: Affects one side of the body.

Based on its coexistence with other movement disorders, dystonia is classified as:

• Isolated dystonia: Dystonia is the predominant symptom, and other brain functions remain intact.
• Combined dystonia: Appears alongside other movement disorders, such as myoclonus or parkinsonism.
• Complex dystonia associated with systemic manifestations: Accompanied by neurological and systemic symptoms unrelated to movement, such as cognitive impairment.

Symptoms

The characteristic symptoms of muscular dystonia include:

• Exaggerated muscle contraction.
• Abnormal postures that persist intermittently or continuously.
• Mirror movements: A dystonic movement or posture appears on one side of the body when performing a voluntary movement on the opposite side.
• Overflow phenomenon: Voluntary movements in the body part affected by dystonia trigger dystonic movements in distant regions.
• Antagonistic gesture or "sensory trick": Certain voluntary gestures reduce the intensity of dystonia, particularly in focal dystonias.
• Tremors and joint pain are common.
• Symptoms worsen with fatigue, stress, and other negative emotional states.

Causes

Dystonia is associated with functional alterations in the brain region where the basal ganglia are located. These structures are responsible for controlling posture and voluntary body movements, as well as the cerebellum, which regulates coordination. Additionally, abnormalities have been detected in the presence and levels of certain neurotransmitters.

Based on the origin of these alterations, the types of dystonia include:

• Idiopathic dystonia: Of unknown origin.
• Hereditary dystonia: Caused by mutations in certain genes. It may be autosomal dominant, autosomal recessive, X-linked recessive, or mitochondrial.
• Acquired dystonia: Stemming from various factors, including focal structural brain lesions, metabolism disorders affecting iron, copper, or dopamine, certain medications and toxins, perinatal brain damage, infections, vascular disorders, neoplasms, autoimmune diseases, neurodegenerative conditions, or psychogenic disorders.

Risk Factors

Factors that increase the risk of developing dystonia include:

• Family history.
• Neurological disorders such as Huntington’s disease, Parkinson’s disease, Wilson’s disease, encephalitis, or multiple sclerosis.
• Use of certain medications, such as antiepileptics or antipsychotics.
• Infections.
• Toxic exposure.
• Occupations requiring highly precise hand movements, such as musicians, artists, or engineers.

Complications

The consequences of dystonia vary depending on the specific type. Constant muscle contractions lead to pain and physical exhaustion. Vision problems or difficulty moving the jaw, swallowing, or speaking may develop, as well as physical disabilities that interfere with daily activities, such as walking. In severe cases of childhood-onset generalized dystonia, patients may adopt a fixed twisting posture and become wheelchair-dependent. Additionally, the disease may lead to depression and social isolation.

Prevention

There are no known ways to prevent dystonia, but symptoms improve with sensory tricks, relaxation, and sleep.

What doctor treats dystonia?

Dystonias are evaluated and treated in neurology and pediatric neurology units.