HAND DYSTONIA: WHAT YOU NEED TO KNOW ABOUT THIS MOVEMENT DISORDER

Dystonia is a neurological disorder that induces unintentional muscle spasms, contractions, abnormal movements, and postures, typically due to neurological disease or a side effect of drug therapy.

While rare, it is the third leading movement disorder in the US, affecting approximately 500,000 adults and children. Hand dystonia tends to occur in those aged 30 to 50 and affects men and women equally.

Hand dystonia affects the muscles in the hand and fingers and the involuntary movements are often painful. It can be debilitating and significantly impact daily activities, lowering a person's quality of life.

The disorder can occur at a local site, in one body part, or as part of a more widespread dystonia affecting other areas of the body.

This article covers the different types of hand dystonia, their causes, and how they can be managed through exercise and other treatments.

Types and Causes of Hand Dystonia

There are several types of hand dystonia. Hand dystonia classifications rely on the underlying cause, the extent of the dystonia, and the type of movement.

Most causes of dystonia arise from disturbances in nervous conduction, usually caused by nerve inhibition at some point of the circuit that governs movement. However, in some instances, nerve dysfunction, sensory disturbance, and aberrant neuroplasticity can also contribute.^[1]

Two of the most frequent types of hand dystonic movements include:

• Dystonic tremor: This type of hand dystonia causes a rhythmic shaking or tremor in the hand, which can get in the way of performing delicate motor tasks.
• Dystonic spasm: This type of hand dystonia causes sudden, painful spasms in the hand and fingers, which can be triggered by specific movements or activities. Spasms can sometimes lead to excessive muscle contractions that cause the wrist to over or under-extend or the fingers to remain curled or extended, leading to abnormal hand postures.

Hand dystonia may occur at any time or be task-specific (known as task-specific dystonia), triggered by a specific task or activity, such as typing, holding a utensil, or golfing.

Other common types include focal hand dystonia, generalized hand dystonia, and secondary dystonia.

Focal hand dystonia

This type of hand dystonia affects a specific hand area, such as the fingers or wrist. Repetitive movements or overuse of the hand are common causes of focal hand dystonia.

Typical forms of focal hand dystonia include:

• Writer's cramp: This is a focal hand dystonia that affects individuals during writing or similar tasks. Common symptoms of hand dystonia include excessive pen gripping, wrist contortions, elbow elevation, and involuntary finger extension, causing the pen to fall. Severe cases may involve shoulder elevation or arm retraction during writing, with sustained hand postures like wrist bending, clenched fist, or finger contractions. These symptoms may cause mild, temporary pain.^[2]
• Musician's cramp: This is a form of hand dystonia that impacts musicians, leading to involuntary movements and muscle spasms while playing instruments that often hinder their performance. Symptoms include loss of fine motor control (especially during fast phrases), excessive curling of the hand or fingers, and "freezing" of the hand (the hand stops moving).^[3]
• Occupational dystonia: This manifests as involuntary muscle contractions and abnormal movements in the hand during specific work-related tasks. It can cause discomfort, impaired motor control, extensive hand movements or a lack of them, and challenges in performing work-related activities effectively. This type can affect typists, golfers or athletes who use sports equipment, construction workers, and those who operate heavy machinery that requires their hands.
• Gamer's thumb: This involves involuntary movements and muscle spasms in the thumb and hand, often triggered by extensive gaming sessions and long-term repetitive use of gaming controllers. The repetitive movements of the thumb and sometimes fingers cause ligaments to rub together in the wrist, resulting in a gamer's thumb. It can lead to cramping, discomfort, reduced hand coordination, and difficulties in engaging in gaming activities.^[4]

Generalized hand dystonia

This form affects major muscle groups in the entire body. In those with generalized hand dystonia, it may impact the hand, arms, and torso, impacting various activities that require hand-arm coordination, including lifting, carrying, and pushing off from the ground. This type of dystonia can cause discomfort that may be debilitating for some until the involuntary contractions cease.

The exact cause of generalized hand dystonia is not fully understood. Yet, evidence suggests it may arise as a result of genetics and environmental exposures, such as injury, toxins, and medications.

Gene mutations in the DYT1 gene may cause generalized dystonia^[5]. Symptoms may spread from the hands and arms to the rest of the body as the condition progresses (especially when present in childhood), or it may involve the whole body at the onset.

Other genetic causes of generalized dystonia include mutations in the following genes^[6]:

• DYT28, leading to DYT-KMT2B dystonia
• TAF1, causing DYT/PARK-TAF1, DYT3, or X-linked dystonia/parkinsonism
• GCH1, causing Segawa syndrome, a type of dopa-responsive dystonia related to parkinsonism
• THAP1, leading to DYT-THAP1
• MR1, responsible for Paroxysmal non-kinesigenic dyskinesia

There are many other kinds of genetic dystonia, most of which relate to Parkinsonism movement disorders.

Secondary hand dystonia

People acquire this type from injuries or other neurological conditions like stroke or Parkinson's disease. It develops as a secondary symptom of an underlying neurological disorder or damage to the brain. Additionally, people with secondary hand dystonia may have widespread dystonia and be unable to move other body parts optimally.

The causes of secondary hand dystonia can be diverse, including:

• Brain injury or trauma
• Stroke
• Infections or inflammation of the brain
• Exposure to certain medications or toxins
• Neurodegenerative disorders, such as Parkinson's disease
• Oxygen deprivation or carbon monoxide poisoning
• Brain tumor

Any of the above factors can interrupt the functioning of the brain's motor control regions, leading to involuntary muscle contractions and abnormal movements in the hand.^[7]

Risk factors that can aggravate symptoms of dystonia include:

• Stress
• Fatigue
• Anxiety
• Lack of sleep

Although research is mixed on the subject, a few medications may cause dystonia in some people.

Diagnosis

There are no tests that diagnose hand dystonia. A doctor will diagnose the condition based on physical findings and the patient's medical history during a consultation.

Treating Hand Dystonia

While there is no cure for hand dystonia, there are several treatment options available for symptom control and improving life quality. These include medications, injections, and physical therapy.

Medications

Medications, such as muscle relaxants and anticholinergics, can help reduce muscle spasms and improve motor control in people with hand dystonia. However, these medications may have side effects and are only effective in a few instances.

Those with dystonia related to Parkinsonism movement disorders may require dopamine agonists or similar medications to help normalize muscle movements and coordination.

Injections

Botulinum toxin injections, also known as Botox injections, can temporarily paralyze the muscles in the hand, reducing involuntary movements and spasms. These injections are typically given every few months and can provide significant relief for some people with hand dystonia.

Physical Therapy and Exercises

Physical therapy and exercises can also be crucial in managing hand dystonia.

A physical therapist can provide instructions for strengthening the muscles in the hands and arms. These exercises can help improve motor control, reduce muscle spasms, and increase hand flexibility and range of motion.

Hand exercises help train the hand in different postures and positions that can give the hand and brain a break from repetitive motions. It also facilitates better neuroplasticity in the brain, which may regulate underlying issues that can contribute, such as seen in musician’s cramps.

Some with hand dystonia may benefit from immobilizing fingers with splints that are not required to perform a movement while practicing the movement.^[8]

Other Treatments

In addition to medications, injections, and physical therapy, other treatments may be beneficial for managing hand dystonia. These include:

• Sensory tricks: Some people with hand dystonia may find relief by using sensory tricks, such as touching a specific part of the hand or using a specific grip or posture. While poorly understood, sensory tricks may temporarily interrupt processes involved in hand dystonia.
• Biofeedback: Biofeedback is a technique that involves sensors that monitor muscle activity and offer feedback to the person. This can help them learn to control their muscles and reduce involuntary movements.
• Deep Brain Stimulation: Deep brain stimulation involves the surgical implantation of probes into the brain that send corrective signals to an affected area. Electrical stimulation of the thalamus may correct symptoms of dystonia. Non-invasive brain stimulation may also improve hand coordination.^[9]
• Surgery: In case of task-specific focal hand dystonia, thalamotomy or globus pallidus internus deep brain stimulation (GPi DBS) has been utilized as a surgical procedure when patients did not respond to other treatments.

Complications and Outlook

Whether complications present themselves or not depends on the type of dystonia. Those with focal hand dystonia may find symptom resolution after performing hand exercises, while others may require intensive lifelong treatment to keep their symptoms under control.

For generalized and secondary hand dystonias, the symptoms will progress to other body areas, and the prognosis is typically worse.

Complications and long-term effects of hand dystonia can include complete loss of hand coordination and movement. Treatment may help prevent or delay these complications.

Tips for Managing Hand Dystonia

In addition to medical treatments and exercises, some lifestyle changes and tips can help manage hand dystonia and improve quality of life. These include:

• Avoiding triggers: If you know that certain activities or movements trigger your hand dystonia, try to avoid or limit them as much as possible.
• Taking breaks: If you have a job or hobby requiring repetitive hand movements, take frequent breaks to rest your hand and prevent overuse.
• Using assistive devices: Assistive devices, such as ergonomic keyboards or writing aids, can help reduce strain on the hand and make daily activities easier.
• Managing stress: Stress can exacerbate symptoms of hand dystonia, so it is essential to find ways to manage stress and relax, such as through meditation or yoga.

Severe hand dystonia can be challenging to live with due to social stigma, frustration, and the inability to perform certain tasks.

It is crucial for those living with the worst form of the condition to have a solid social support network and to consult with a mental health specialist if they battle to manage their stress or are suffering from symptoms of anxiety or depression.

Conclusion

Hand dystonia is a complex and often debilitating disorder that can seriously impact a person's daily life. However, suitable treatment and management strategies can improve symptoms and maintain a good quality of life.

If you are experiencing symptoms of hand dystonia, it is beneficial to book an appointment with a medical professional for an exact diagnosis and a personalized management plan. With a tailored approach, you can effectively keep symptoms of hand dystonia under control and continue to live a fulfilling life.

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