Also called: Disorders of Movement
Movement disorders are neurological conditions that prevent patients from controlling their muscles and, therefore, their movements. Some patients experience facial tics or trembling hands while others will uncontrollably flail one or more limbs. Conversely, some patients with movement disorders are unable to move a limb despite their intentions.
Most movement disorders involve the voluntary muscles, which a person controls through conscious thought. Conscious movement requires complex processes involving neurons (nerve cells) in several parts of the brain, spinal cord and muscles. A movement disorder may occur if the communication between any of these parts is slowed, disrupted or blocked. This can result from a number of causes, including physical injuries (e.g., head injury, spinal cord injury, stroke), genetic mutations and infections.
There are dozens of types of movement disorders. Some of the most common are Parkinson’s disease and essential tremor. Both cause uncontrollable shaking, but Parkinson’s disease is also associated with severe complications. Patients may also have one of the many tic disorders (e.g., Tourette syndrome), which cause uncontrollable muscle and vocal spasms. Other examples of movement disorders include Bell’s palsy, Huntington’s disease and locked-in syndrome.
Several, somewhat distinct, types of movements help characterize most movement disorders. Exaggerated or uncontrollable movements are termed hyperkinetic. They may be rapid (e.g., tics, hemiballismus) or slow and rhythmic (e.g., athetosis, dystonia). Other movements are hypokinetic, which are delayed or absent (e.g., paralysis, ataxia).
The diagnosis of a movement disorder can be complex. This is because the nervous system is a complicated and multifaceted system that is not completely understood. Diagnosis will likely require eliminating other possible disorders that could cause similar signs and symptoms. Because diagnosis is often complicated, the process may require visiting several specialists in neurological and muscular diseases, in addition to the patient’s primary care physician.
Proper diagnosis of a movement disorder is essential in order to receive adequate treatment. Some types may cause similar symptoms, but while one form responds to a certain medication, the other may not. In addition to medications, surgery may also help relieve the symptoms of some movement disorders. This may entail surgical procedures (e.g., pallidotomy, thalamotomy) that remove certain parts of the brain involved in movement. Surgery may also be necessary to implant devices that help control the nerve action of the brain or spinal cord. Rehabilitation is likely to be part of the treatment and in some cases may be the best treatment options available. Examples of rehabilitation include physical therapy and occupational therapy.
About movement disorders
A movement disorder, or dyskinesia, is a neurological condition that limits a patient’s ability to control movement. Depending on the condition and the area of the brain affected, the movements may either be exaggerated or occur beyond the patient’s control. Conversely, some movement disorders are characterized by slowed movement or the inability to move.
Voluntary movements – those that a person consciously thinks about and controls – require complex processes. Movement begins with nerve signals that are processed in multiple parts of the brain. The signals then travel through the spinal cord to motor neurons, the nerve cells that signal muscles. The motor neurons send neurotransmitters to muscle fibers that cause contraction or relaxation. In addition to voluntary movements, there are also reflexes and internal muscle movements, such as those that involve circulation and breathing. They are controlled by different aspects of the nervous system, but may also be impacted by movement disorders.
Any condition that disrupts the communication process between the nerves and muscles and causes problems with movement may be considered a movement disorder. These conditions include head injury, stroke, infection, genetic defects and nerve degeneration in the brain. The severity of the disorder is likely linked to the degree of damage to the nerve cells (neurons). It may also reflect which section or sections of the brain are affected.
Many movement disorders involve damage or disease to the basal ganglia, which is located deep within the brain and is integral to many aspects of movement. Other movement disorders may result from damage or disease to the cortex, brain stem or cerebellum, each of which are also associated with aspects of movement. For example, Parkinson’s disease involves the destruction of cells within a small region of the brain stem known as the substantia nigra. These cells produce and release a neurotransmitter called dopamine, which controls movement and balance in the body. Dopamine is vital to proper central nervous system functioning and helps electrochemical signals move from one neuron to another. A sharp decline in dopamine production results in most of the symptoms of Parkinson’s disease.
Types and differences of movement disorders
There are many types of movement disorders. Certain types are relatively common, such as Parkinson’s disease. However, many are considered rare with no accurate estimates of national prevalence.
Movement disorders can generally be classified as primarily hyperkinetic (causing an increase in movement) or primarily hypokinetic (causing a decrease in movement). Some movement disorders involve both hyperkinetic and hypokinetic symptoms.
For example, the motor symptoms associated with Huntington’s disease are primarily hyperkinetic. Huntington’s disease results in the degeneration of neurons in the basal ganglia, which causes characteristic involuntary, jerking movements. The movements associated with Huntington’s disease are called chorea and are often described as dance-like.
Conversely, Bell’s palsy is a movement disorder that is primarily hypokinetic. Bell’s palsy or facial palsy occurs when the nerve controlling facial muscles becomes compressed, inflamed or swollen. This leads to facial paralysis (or palsy) and weakness in the muscles controlling facial expressions and movement.
Parkinson’s disease is a common type of movement disorder that involves both hypokinetic and hyperkinetic movements. Parkinson’s disease is caused by the degeneration of cells that produce dopamine. This results in the various motor symptoms associated with the disease such as tremor, rigidity, bradykinesia and postural instability.
Some examples of primarily hyperkinetic movement disorders are:
- Essential tremor. One of the most common types of movement disorders. Most cases of essential tremor are associated with aging, though the symptoms can also begin in adolescence and early adulthood. Patients with this condition typically experience trembling when performing voluntary movements. The hands are most frequently affected, but shaking may also occur in the head, legs, tongue and arms. In some cases, the trembling may be severe enough to prevent patients from performing everyday tasks, such as dressing themselves.
- Dystonias. This group of disorders are marked by sustained muscle contractions that force the body into unusual postures, abnormal twisting or repetitive movements. It is caused by abnormalities in the basal ganglia.
- Tic disorders. There are many types of these disorders, which are characterized by uncontrollable and repetitive movements or vocalizations (tics). The tics may be simple movements that involve just one muscle group, such as head shaking, blinking, coughing or throat clearing. Alternatively, tics may also be more complex, such as self-hitting, jumping, twirling or repeating words.
- Tardive dyskinesia. Movement disorder associated with the long-term use of some medications for psychiatric, gastrointestinal and neurological disorders. Patients experience a wide-range of involuntary facial movements including grimacing, lip smacking and blinking. In some cases, the limbs may also become involved. Part of the treatment for tardive dyskinesia may require discontinuing or changing medications, but this should only be done under the guidance of a physician.
- Paroxysmal choreoathetosis. A disorder involving involuntary movements of the limbs, trunk and facial muscles. These movements may last for as long as an hour. Most patients with the disease exhibit the first symptoms during early adolescence and the severity of symptom attacks tend to lessen over time.
- Joubert syndrome. Disease characterized by a lack or underdevelopment of the cerebellar vermis, a part of the brain involved in balance and coordination. The disease causes abnormal breathing and jerky eye movements in infants and may also cause physical deformities. Most cases occur sporadically, though some are related to family history.
- Sydenham’s chorea. Unique among the movement disorders because it is known to result from bacterial infections. Female patients between 5 and 15 years of age seem most prone to this movement disorder. The disease causes rapid and irregular movements of muscles in the face, neck, trunk and limbs. The disease may be self-limiting and pass within three to six months, though recurrences have been recorded, especially during pregnancy.
Movement disorders that are primarily hypokinetic include:
- Amyotrophic lateral sclerosis (ALS). Also known as Lou Gehrig’s disease, this disease involves damage to the nervous system resulting in a gradual decrease in movement. Eventually, the disease causes paralysis.
- Multiple sclerosis. A common neurological disorder thought to be caused by the immune system attacking the body’s neurons. One third of patients eventually become paralyzed.
- Multiple system atrophy (MSA). In addition to movement, this group of slowly progressive disorders may also affect the patient’s blood pressure and excretory systems. The symptoms of each disease vary but all reflect damage to the patient’s nervous system.
- Angelman syndrome. Patients with Angelman syndrome tend to have movement and balance problems, in addition to developmental delays, seizures and skull malformations. Most cases of the disorder result from inherited genetic mutations, but some may also occur spontaneously.
- Cerebellar hypoplasia. Patients with cerebellar hypoplasia have a cerebellum that is not correctly formed. This part of the brain is involved in movement and balance. The deformation may occur sporadically or due to inherited genetic mutations. The disease causes symptoms that become progressively more severe with time and include developmental delays, ataxia, seizures, dizziness and imbalance.
- Corticobasal degeneration. Disease that causes the outer layer (cortex) and several other areas (including the basal ganglia) of the brain to degenerate. In most patients it begins after the age of 60. Symptoms typically include stiffness, shakiness, jerkiness or slowness of the extremities on the right or left side of the body. Over time, the symptoms spread to the other side and also become more severe.
- Progressive supranuclear palsy. A rare disorder that tends to develop in patients after age 40. The condition causes loss of control of gait, balance and eye movement in 20,000 Americans according to the National Institutes of Heath. Due to the balance problems that accompany the disease, progressive supranuclear palsy may initially be diagnosed as an inner ear condition. The disease progresses rapidly and patients typically die within 6 years of the onset of symptoms.
- Myotonia. Disorder characterized by a delay in muscle relaxation. This may affect many everyday activities, such as the patient being unable to release the grip following a hand shake. There are several types of myotonia and most result from inherited genetic conditions.
- Dyspraxia. A movement disorder that limits patients’ ability to perform motor tasks. It has many other names, including clumsy child syndrome and developmental coordination disorder. Children with dyspraxia demonstrate a delay in achieving developmental movement milestones, such as rolling over, sitting, standing and walking.
- Cerebellar degeneration. This group of non-specific conditions involves atrophy of the cerebellum, a part of the brain that is involved in balance and movement. When the spinal cord is also involved, it is termed spinocerebellar degeneration. Examples of cerebellar degeneration include Friedreich’s ataxia and Machado-Joseph disease. There are many possible causes of these conditions, though they are often hereditary. Cerebellar degeneration may also occur spontaneously or result from stroke, multiple sclerosis, cancer, alcohol abuse or vitamin deficiency.
- Neurodegeneration with brain iron accumulation. A rare, inherited movement disorder characterized by degradation of the nervous system. The disease typically starts in patients younger than age 10. They experience a great variety of symptoms, including jerky or slow writhing movements and distorting contractions of the muscles of the limbs, face and trunk. Eventually, the disease typically causes patients to require a wheelchair for mobility. This disease may also be referred to as Hallervorden-Spatz syndrome.
In addition, there are some disorders that have paralysis as the primary symptom. For example, locked-in syndrome involves the paralysis of all voluntary muscles other than those involved in eye movement. It is usually the result of damage to the pons, part of the brain stem that regulates communication between sections of the brain. The pons may be damaged by physical injuries to the brain, disease that destroys or degenerates the myelin sheath that protects nerve cells, diseases of circulatory or nervous system (e.g., Guillain-Barré syndrome) or medication overdose. Patients with locked-in syndrome remain conscious but are unable to speak or move.
Risk factors and causes of movement disorders
Movement disorders result from blocked, slowed or distorted communication between the central nervous system and the muscles. The cause of the communication interference may vary and include:
- Traumatic injury. Many parts of the brain are involved in processing and transmitting the nerve signals necessary for coordinating balance and movement. They are susceptible to damage from head injuries. Spinal cord injuries may also lead to movement disorders by blocking the transmission of nerve signals from the brain to muscles below the head.
- Stroke. Much like head injuries, stroke can also damage parts of the brain involved in movement. The lack of oxygen getting to nerves in the brain (neurons) can cause the cells to die.
- Genetic mutation. Genes provide the instructions for all of the body’s functions. While some mutations may occur with no apparent effects, others can cause nerve or muscle degeneration that result in a movement disorder. Mutations may occur spontaneously or may be inherited from a parent who may or may not have had the disorder.
- Medications. Several types of medications (e.g., for psychiatric, gastrointestinal and neurological disorders) may cause damage to the brain and nerve cells. Physicians will likely monitor the patient’s side effects while under these medications to prevent occurrence of tardive dyskinesia and other movement disorders.
- Infection. In rare cases, Streptococcus bacterial infections may lead to Sydenham’s chorea.
Certain factors put some populations at greater risk for developing movement disorders. They vary greatly among the many disorders and some groups who are at greater risk for one type may be at less risk for another. Risk factors for movement disorders may include:
- Family history of disease
Signs and symptoms of movement disorders
The movements that are symptomatic of movement disorders can vary greatly. In general, they may be classified as hyperkinetic or hypokinetic.
Hyperkinetics are exaggerated, unintended or uncontrolled movements. Some varieties of hyperkinetics include the following:
- Chorea and athetosis. Athetosis is slow, writhing, nearly continuous movements in the muscles farthest from body core (distal muscles). Chorea is rapid, jerky motions of the facial and limb muscles. In many cases, the two occur together.
- Dystonia. Slow change in normal posture of one or more joints that may occur in conjunction with athetosis.
- Tics. Involuntary muscular or vocal spasms that occur faster than athetosis or dystonia. In most cases, a patient experiences tics in the same area of the body, but they can also be more general. Examples of tics include blinking, clearing throat, facial twitching, grunting, shrugging shoulders and sighing.
- Hemiballismus. Rapid, irregular muscle jerking that cannot be controlled by the patient. Severe forms of hemiballismus may involve sudden flinging of an arm or leg.
- Myoclonus. Sudden rapid, brief, irregular movement of many parts of the body at one time. There are also uncommon forms of myoclonus that are characterized by rhythmic movements.
- Tremors. Rhythmic shaking. There are three types of tremors. One form most frequently occurs at rest. A second type, postural tremors, are strongest when holding a limb against gravity, such as when holding an arm straight out from the body. Intention tremor is the third type and occurs in conjunction with voluntary movement (e.g., when trying to write or pick something up).
In contrast to the hyperkinetic movements, hypokinetic movements are slower than the patient intended or they do not occur at all. They may also be referred to as akinesia (lack of movement) or bradykinesia (slow movement). One of the most severe forms of hypokinetic movement is paralysis, which is the inability to move muscles and may also involve loss of sensation. Ataxia is also a type of hypokinesis that prevents patients from responding to verbal commands to move.
Diagnosis methods for movement disorders
Diagnosing a movement disorder is complex. In many cases it requires ruling out other possible causes of symptoms. This is especially important since treatment for one disorder may have no effect on another condition. The diagnosis process is likely to take some time and may require appointments with several specialists, including neurologists (physician specializing in the brain and nerves), rheumatologists (physician specializing in muscles) or ophthalmologists (physician specializing in the eyes).
A physical examination and neurological examination are often vital to the diagnosis of movement disorders. During these examinations, a physician will test balance, reflexes and eye movement. The examinations will also check for other signs and symptoms that may be indicative of certain movement disorders or other diseases.
The physician will also likely review the patient’s medical history. This will include a description of the patient’s symptoms, including details on when symptoms began and how long they typically last. Many of the movement disorders are inherited, so the patient may also be asked about the occurrence of similar symptoms or movement disorders in family members.
In addition to these basic examinations, other tests are likely to be required to diagnose a movement disorder. These may include:
- Blood test, urine test and spinal tap. Fluid samples may be tested for enzymes and other indicators of movement disorders. In rare cases, blood may also be tested for antibodies that may indicate Sydenham’s chorea. DNA tests may also be performed on fluid samples to identify or eliminate disorders resulting from genetic mutations.
- Imaging tests. Several non-invasive or minimally invasive techniques allow physicians to view a patient’s brain, nerves and muscles. In some case, these tissues may show damage that is characteristic of certain diseases. Types of imaging tests include MRI (magnetic resonance imaging), CAT scan (computed axial tomography), PET scan (positron emission tomography) and SPECT scan (single photon emission computed tomography).
- Electromyogram (EMG) and nerve conduction velocity (NCV) tests. Measures electrical activity of muscles and nerves. Results may indicate portions of the body with reduced or blocked signal activity. Certain movement disorders may be recognized by characteristic results of these tests.
- Electroencephalogram (EEG). Measurement of the electrical activity of the brain using electrodes placed on the scalp. Brain damage may be suspected when the electrical activity occurs in atypical patterns or is greater or less than expected.
- Muscle or nerve biopsy. Removing a sample of muscle or nerve for microscopic examination. Many of the movement disorders result from damage to muscles or nerves that may become apparent when viewed through a microscope.
Treatment/prevention of movement disorders
Treatment options for movement disorders vary greatly. In some cases, the disorder may require no treatment because it is either mild or may pass naturally with time. Most movement disorders cannot be cured with treatment, but the symptoms may be managed.
Treatment for movement disorders is usually individualized. There are many medications available to treat movement disorders. Most are only available with a physician’s prescription and should be taken exactly as directed. Some medications that may be prescribed include:
- Seizure medications
- Anti-anxiety medications
- Dopamine depletors or dopamine stimulators
- Beta blockers
- Botulinum toxin
Medications are usually the first step in treating movement disorders. In some cases, patients may not respond to the prescribed medications or may not be able to take them due to intolerable side effects. If this occurs, there are other treatment options. They include:
- Implantable devices. Deep brain stimulation is a process that requires the implantation of a battery powered neurostimulator. It delivers an electric charge to areas of the brain that control movement and can temporarily correct disorders. In addition, a spinal pump may be inserted near the spinal cord. It delivers muscle relaxants that help control spasticity.
- Ablation surgery. Ablation is the surgical removal of parts of the brain and may reduce uncontrollable movements. Pallidotomy removes part of the globus pallidus, to treat Parkinson’s disease. Thalamotomy is removal of part of the thalamus and may be required to reduce tremors.
- Physical therapy. A mixture of exercises, massage and other treatments to maintain muscle strength and flexibility. A physical therapist is likely to teach the patient exercises that he or she can do at home to strengthen and retrain muscles, which may help control symptoms of the movement disorder. Physical therapy may also include training with canes, walkers, wheelchairs or other assistive devices to improve mobility.
- Occupational therapy. Similar to physical therapy but focuses on improving the patient’s fine motor skills. It aims at improving the patient’s ability to accomplish daily activities like dressing and personal hygiene.
- Speech therapy. Therapy to train or retrain the patient’s speech skills. In addition, the patient may be taught to use voice amplifiers or similar devices.
Though there are treatments for many types of movement disorders, there remains some that have shown no response to a variety of treatment methods.
In most cases, the development of a movement disorder cannot be prevented. However, patients may be able to act to reduce the severity and frequency of symptom occurrence. This may be accomplished by consuming a healthy diet and reducing the intake of alcohol and stimulants (e.g., caffeine). Behaviors recommended for healthy living (e.g., reducing stress, getting regular exercise and adequate sleep) may also help reduce symptom occurrence.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with healthcare professionals regarding their condition. Patients may wish to ask their doctor the following questions related to movement disorders:
- What has caused my movement disorder?
- What tests need to be performed to diagnose my disorder?
- Will diagnosis of my disorder require visiting a specialist? If so, can you recommend one?
- What type of movement disorder do I have?
- Are there other diseases that could cause my symptoms?
- Can my disorder be treated? Are there side effects?
- Will treatment require surgery? If so, what are the risks?
- Can the symptoms of my movement disorder be prevented?
- Will my children develop the same disorder?
- I have a family member who developed a movement disorder, is there a way to know if I will get it too?
- Can you recommend a support group for my movement disorder?