Cerebral palsy (CP) refers to a group of permanent disorders affecting a person’s ability to move, maintain posture, and balance, resulting from non-progressive disturbances in the developing fetal or infant brain. It is the most common cause of physical disability in childhood. Dyskinetic cerebral palsy is a specific subtype characterized by the inability to control muscle movement, leading to involuntary and uncontrolled motions. Unlike the stiffness of spastic CP, the dyskinetic form involves fluctuating muscle tone and movements that interfere with voluntary actions.
The Defining Characteristics of Dyskinetic CP
The defining feature of dyskinetic CP is the presence of involuntary, fluctuating movements, collectively known as dyskinesia. Dyskinesia is categorized into three distinct patterns: athetosis, chorea, and dystonia. Individuals often experience a combination of these patterns, frequently referred to as choreoathetosis.
Athetosis involves slow, continuous, writhing movements, typically affecting the hands, feet, arms, and legs, making fine motor tasks challenging. Chorea is characterized by rapid, abrupt, and unpredictable movements, often described as jerky. Both result from poor control over muscle tone, which fluctuates between being too loose (hypotonia) and too stiff (hypertonia).
Dystonia involves sustained or repetitive involuntary muscle contractions, often causing twisting and awkward postures. These contractions can be painful and may be focal or generalized across the trunk and limbs. All three types of involuntary movements increase significantly with emotional stress or attempts at purposeful movement. These motions typically disappear entirely when the person is relaxed or asleep.
Underlying Causes and Associated Risk Factors
Dyskinetic CP is directly linked to damage occurring in the deep gray matter structures of the brain, specifically the basal ganglia and, in some cases, the thalamus. These regions regulate voluntary movement and inhibit unwanted motions. Damage to these areas disrupts the signaling pathways responsible for smooth, coordinated action, leading to the uncontrolled movements characteristic of dyskinesia.
The most common causes of this brain injury pattern are severe hyperbilirubinemia, leading to kernicterus, and perinatal asphyxia. Hyperbilirubinemia is an excessive buildup of bilirubin, a toxic breakdown product of red blood cells, if left untreated in infants. Kernicterus, the resulting brain damage, shows a strong association with dyskinetic CP and prominent dystonia.
Perinatal asphyxia, a lack of sufficient oxygen during or immediately following birth, is the second major risk factor. This oxygen deprivation causes lesions in the basal ganglia, leading to dyskinetic CP. While it occurs in both full-term and premature infants, it is often the dominant type of CP seen in term-born babies who have experienced these specific brain injuries.
Diagnostic Confirmation and Clinical Assessment
Diagnosing dyskinetic CP relies on clinical observation of the child’s movement patterns and muscle tone over time. A neurological assessment looks for fluctuating muscle tone and involuntary movements, distinguishing it from other CP subtypes, such as spastic CP. Because these movements may not be clearly apparent right away, a definitive diagnosis is often made after the child is 18 months old, once movement patterns become established.
Brain imaging, particularly Magnetic Resonance Imaging (MRI), is important for confirming the diagnosis and determining the cause. An MRI detects specific damage in deep brain structures, such as the basal ganglia, supporting the clinical suspicion. Imaging is also useful for ruling out progressive neurological disorders that mimic early signs of cerebral palsy. Clinical history, neurological exam, and supportive imaging confirm the non-progressive nature of the condition.
Comprehensive Management and Support
Management for dyskinetic CP requires a comprehensive, multidisciplinary approach focused on maximizing function and minimizing the impact of involuntary movements. Physical therapy (PT) and occupational therapy (OT) are foundational. They maintain joint range of motion and develop functional skills for daily activities. Therapists use targeted exercises and positioning techniques to manage fluctuating muscle tone and improve control.
Medications are used to manage severe involuntary movements and abnormal muscle tone. Specific oral medications, such as trihexyphenidyl, reduce the intensity of dystonia and choreoathetosis by acting on the nervous system. Muscle relaxants, like oral baclofen, may also ease muscle rigidity and spasms. Medication choice and dosage are highly individualized and adjusted over time based on the person’s response.
Assistive technology provides support, helping individuals compensate for challenges with movement control. This includes specialized seating and mobility equipment that offers trunk support to minimize involuntary movements and improve posture. Augmentative and alternative communication (AAC) devices are commonly used, as dyskinesia often affects speech muscles, making verbal communication difficult.