Athetosis is a neurological symptom characterized by involuntary, slow, and continuous movements that affect the limbs and other parts of the body. It is classified as a form of dyskinesia, which is a broad term for abnormal or impaired voluntary movement. The term itself originates from a Greek word meaning “without position,” accurately reflecting the difficulty a person has in maintaining a stable posture. This movement disorder is not a stand-alone disease but rather the manifestation of damage to specific motor control centers in the brain. The constant, uncontrolled motion significantly impacts daily function, especially tasks requiring fine motor skills.
Characteristics of Athetotic Movements
The movements associated with athetosis are often described as writhing, convoluted, or “worm-like” movements that are non-rhythmic and fluid. They typically involve the distal extremities, such as the fingers, hands, toes, and feet, causing them to flex and extend in an irregular, unpredictable pattern. The slow, continuous nature of these motions makes it almost impossible for an affected individual to hold a steady grip or maintain a fixed posture.
Athetotic movements can also affect the trunk, neck, face, and tongue, which can lead to difficulties with speech, swallowing, and maintaining a neutral facial expression. The muscle tone in affected individuals often fluctuates unpredictably, shifting between states of hypotonia (floppy) and hypertonia (stiff), further complicating motor control.
Athetosis frequently worsens when the person attempts to initiate a voluntary action or is experiencing emotional stress. The movements cease entirely when the person is asleep. Athetosis is often discussed alongside chorea, a related dyskinesia that involves quicker, more jerky movements; when both are present, the condition is referred to as choreoathetosis.
Conditions Linked to Athetosis
Athetosis is primarily a symptom that signals underlying damage to a specific region of the brain responsible for movement coordination. The most common cause is injury to the basal ganglia, a group of deep brain structures that includes the corpus striatum and putamen. Damage to these structures disrupts the neural pathways that regulate the initiation and smoothing of muscle movements.
The leading cause of athetosis, particularly in children, is dyskinetic cerebral palsy, which accounts for approximately 10 to 15 percent of all cerebral palsy cases. This damage typically occurs before, during, or shortly after birth due to complications like severe oxygen deprivation (asphyxia) or high levels of bilirubin, known as kernicterus. Kernicterus causes brain damage by specifically targeting the basal ganglia.
Other, less common causes include specific genetic or metabolic disorders that affect the brain’s chemistry or structure, such as Huntington’s disease or Wilson’s disease. Athetosis can also manifest in adults following an acute neurological event, such as a severe stroke that damages the basal ganglia or thalamus.
Identifying and Managing Athetosis
Diagnosis
Identification is based on clinical observation of the characteristic slow, writhing, involuntary movements by a neurologist or movement disorder specialist. A thorough medical history is taken to determine potential underlying causes, focusing on birth complications or a family history of neurological disorders. Brain imaging, most commonly Magnetic Resonance Imaging (MRI), is often used to visualize the extent of damage, which frequently reveals lesions in the basal ganglia.
Management and Treatment
Management centers on improving function and quality of life, as the underlying neurological injury is often permanent. A multidisciplinary approach is employed, beginning with non-pharmacological interventions designed to improve stability and control.
Physical therapy and occupational therapy are foundational, focusing on strengthening controlled movements and teaching adaptive techniques for daily tasks, such as feeding and dressing. Speech therapy is also a common component, addressing movements that impact the muscles of the face, tongue, and throat, which interfere with clear communication and safe swallowing.
Assistive devices, including specialized seating, braces, and communication aids, help compensate for the lack of muscle control. For more severe cases, pharmacological treatment may be considered to reduce the excitability of the motor system. Medications may include:
- Muscle relaxants like baclofen.
- Agents that modulate neurotransmitters, such as anti-dopaminergic drugs.
- Clonazepam, to help dampen the involuntary motions.