Hyperkinetic Movement Disorder (HMD), also called Dyskinesia, refer to types of excessive, abnormal and involuntary movements. These movements can prevent maintaining a stable posture, and sometimes cause significant disability and impairment in daily activities.
Chorea (means to dance) refers to ongoing irregular, discrete involuntary dance-like flowy movements, especially of the hands and feet.
Athetosis refers to slow, writhing or convoluted, and continuous worm-like movements usually of the limbs (fingers, hands, toes, and feet and in some cases, arms, and legs). The trunk, neck, face, and tongue can also be affected.
Hemiballismus is a rare but violent flinging-out involuntary movement of the hands and legs on one side of the body.
Note – Pseudo-athetosis is a movement disorder, very similar to athetosis, however, the underlying cause is loss of proprioception (sense of perceiving location, position, and movement), due to damage to the connections between the brain (primary somatosensory cortex) and the muscle and joint receptors).
It is a movement disorder that causes the muscles to contract involuntarily. This can cause repetitive or twisting movements, cramps, or abnormal posture. The condition can affect one part of the body (focal), two or more adjacent parts (segmental), or all parts of the body (general).
It refers to the sudden, brief involuntary twitching or jerking of a muscle or group of muscles. It may not always represent a disease or abnormality and may sometimes be a natural physiological occurrence due to muscle fatigue, anxiety, exercise while falling asleep, or low levels of salts like magnesium.
These are sudden repetitive abnormal movements (motor tics) or sounds (phonic tics), which come on due to and bring relief to, an uncontrollable sensation of urge. They usually start in childhood, are not serious, and can reduce over time. Examples include repeatedly blinking the eyes, shrugging shoulders, leg/arm/neck jerks, clapping, mouth movements, throat clearing, facial expressions, grunting sounds, or blurting out words. Tics are partially controllable or suppressible as the patient can recognize the onset of the urge.
Tremors are oscillating rhythmic alternating movements involving one or more joints or parts of the body. While the other movements described above are more random, irregular, and exaggerated, tremors are regular and more subtle.
Most of these abnormal movements occur as part of the damage to the area of the brain called the basal ganglia that control the body’s voluntary movements. The basal ganglia can approve or reject movement signals, help one control certain specific muscles, and further refine movements based on sensory signals. Other areas of the brain that can also cause such abnormal movements when damaged are the thalamus (motor and sensory relay center), hippocampus (area of learning and memory), and sometimes the cerebellum (responsible for muscle coordination, movement and balance).
Damage to the mentioned brain structures resulting in abnormal involuntary exaggerated movements can occur due to many causes:
- Birth Injury: Trauma during delivery, lack of adequate oxygen during birth, and jaundice in the newborn (kernicterus). In such cases, there may be associated cerebral palsy, developmental delay, or speech/hearing impairment.
- Genetic/inherited conditions: Huntington’s disease (chorea with cognitive decline and behavioral changes), Tourette’s syndrome (motor and phonic tics), essential tremor, and other rarer genetic diseases.
- Physical brain injury
- Excess metal deposits (copper – Wilson’s disease, iron – hemochromatosis, mercury)
- Infections (HIV, cryptococcal, streptococcal infection in children – called Sydenham’s chorea, toxoplasmosis, TB, meningitis, and encephalitis)
- Side effects of some drugs (cocaine, levodopa, some antiepileptics like phenytoin and antipsychotics)
- Poisoning (carbon monoxide, alcohol)
- Sudden decrease or increase in blood sugar
- Pregnancy (chorea gravidarum)
- Neurodegenerative conditions like amyotrophic lateral sclerosis-ALS
- Autoimmune diseases (like lupus, thyrotoxicosis), multiple sclerosis
- Parkinson’s Disease (tremors and dystonia)
- Liver/Kidney failure
- Idiopathic (unknown cause)
There are also two specific kinds of drug-induced dyskinesia:
Levodopa-induced dyskinesia occurs as a delayed side effect of this drug for Parkinson’s disease. This is managed by modifying levodopa dosage, or using a class of medicines called dopamine agonists.
Tardive dyskinesia is caused by the long-term use of neuroleptic (antipsychotic) drugs, which are used to treat psychiatric conditions. Stopping or tapering these drugs is required in such cases.
The doctor will make a provisional symptomatic diagnosis based on the history, description and observation of the dyskinesia. Additional tests for diagnosing the root cause will involve blood tests, CT/MRI, EEG, and EMG. Blood tests may be quite detailed to exclude multiple conditions.
Treatment revolves around lifestyle therapy. This may be a combination of physical therapy and exercises with or without adaptive or orthotic equipment, speech therapy, and counseling and behavioral therapy for anxiety and stress management. In all cases, the underlying primary cause should be diagnosed and treated effectively.
Some medicines are available to control these movements. These include:
- antimuscarinic-antispasmodics: trihexyphenidyl and benztropine
- antipsychotics (anti-dopamine): tetrabenazine (only FDA-approved drug for Huntington’s chorea), haloperidol, chlorpromazine, and thiopropazate
- anti-epileptics: valproate, carbamazepine, and benzodiazepines like diazepam, clonazepam
- muscle relaxant: baclofen
- botulinum toxin injections for focal dystonia
A procedure called deep brain stimulation (DBS) may be performed in some cases. Sometimes brain surgery is done in severe and non-responsive cases of such abnormal movements.
Understanding Tremors – Parkinson’s Disease and Other Conditions
REFERENCE – Hyperkinetic Movement Disorders