Athetosis is a type of dyskinesia, which describes a group of movement disorders characterized by involuntary muscle actions. This neurological symptom involves slow, continuous, and writhing movements that interfere with a person’s ability to maintain a stable posture. Understanding athetosis is important because it is often a long-term symptom of an underlying condition. The movements are unintentional and can affect various parts of the body, making everyday activities challenging.
Understanding Athetosis: Defining the Movement
Athetosis is defined by its characteristic slow, convoluted, and writhing movements, often described as having a worm-like or sinuous quality. These movements are involuntary, meaning they cannot be consciously controlled, and they tend to be continuous during wakefulness. The motions are smooth and flowing, differentiating them from the rapid, jerky movements seen in a related condition called chorea.
The movements most frequently involve the distal extremities, such as the fingers, toes, hands, and feet, causing them to twist and turn unpredictably. This activity can also extend to the arms, legs, neck, face, and trunk, sometimes making it difficult to hold a stable posture. Attempts to perform a purposeful action often intensify the involuntary movements, a phenomenon known as muscle overflow. The movements typically cease or significantly diminish when the person is asleep.
The Neurological Basis: What Causes Athetosis
Athetosis is a symptom arising from damage within a specific area of the brain responsible for regulating movement. The condition results from a lesion, or injury, primarily in the basal ganglia, a collection of deep brain structures that coordinate muscle control and posture. Specifically, damage to the striatum (which includes the caudate nucleus and putamen) disrupts the brain’s ability to refine and suppress unwanted movements.
This damage interferes with the complex circuit that controls voluntary movement, leading to an imbalance in neurotransmitter activity, particularly involving dopamine. The most common underlying cause of athetosis is athetoid or dyskinetic cerebral palsy, which arises from brain injury occurring before, during, or shortly after birth. This injury is often linked to perinatal issues like a lack of oxygen (asphyxia) or severe jaundice (hyperbilirubinemia), which can lead to a condition known as kernicterus.
Other, less frequent causes include acquired brain injuries later in life, such as those resulting from a stroke, trauma, or certain neurodegenerative diseases. In all cases, the common factor is the disruption of the basal ganglia’s function, which impairs the brain’s filtering mechanism for motor commands, leading to the uncontrolled, fluctuating movements.
Identifying Athetosis and Its Functional Effects
Clinicians identify athetosis primarily through observation and a comprehensive movement assessment, often differentiating it from other movement disorders like tremor or dystonia. A thorough medical history is taken to look for perinatal complications or acquired brain injuries that might explain the symptoms. Imaging studies, such as magnetic resonance imaging (MRI), are used to confirm lesions in the basal ganglia, which supports a diagnosis of the underlying cause.
The involuntary movements impose significant challenges on an individual’s daily life, affecting motor and non-motor functions. Fine motor skills are particularly impaired, making simple tasks like writing, buttoning clothes, or self-feeding difficult. Trunk instability is common, which affects the ability to maintain a stable sitting or standing posture, and can lead to difficulties with balance and mobility.
Athetosis can also affect the muscles of the face, mouth, and throat, leading to difficulties with articulation, resulting in slurred speech (dysarthria). Movements of the tongue and pharynx can interfere with swallowing, increasing the risk of aspiration and making it hard to consume enough calories. The constant, uncontrolled muscle activity requires a substantial amount of energy, which contributes to fatigue and higher caloric needs.
Current Approaches to Management
Management of athetosis is a lifelong process focused on reducing symptoms and maximizing functional independence, as there is currently no cure for the condition. A multidisciplinary team, including neurologists and various therapists, collaborates to create an individualized treatment plan.
Therapeutic Interventions
Physical therapy is a foundational component, aiming to maintain range of motion, prevent fixed joint deformities, and improve muscle strength against the constant involuntary movements. Occupational therapy focuses on helping individuals adapt to their environment and manage activities of daily living through specialized techniques and assistive technology. Speech therapy addresses challenges with articulation and swallowing by working on breath control, vocalization, and strengthening the oral motor musculature.
Pharmacological interventions are often used to reduce the severity of the involuntary movements or associated muscle stiffness. Medications such as anticholinergics (like Trihexyphenidyl) are commonly prescribed to block specific chemical messengers that contribute to the uncontrolled motions. Other options include GABA agonists (like Baclofen) and benzodiazepines, which act as muscle relaxants to help decrease muscle tone and involuntary spasms. In some severe cases, procedures like deep brain stimulation or intrathecal baclofen pump implantation may be considered to manage disabling movements.