Athetoid cerebral palsy

Hypoxic-ischemic brain injury is a form of cerebral hypoxia in which oxygen cannot perfuse to cells in the brain. Lesions in the putamen and thalamus caused by this type of brain injury are primary causes of ADCP and can occur during the prenatal period and shortly after.[1] Lesions that arise after this period typically occur as a result of injury or infections of the brain.[7] Cerebral cortex and white matters are often relative spared, so intelligence is often normal.

Bilirubin encephalopathy, also known as kernicterus, is the accumulation of bilirubin in the grey matter of the central nervous system. The main accumulation targets of hyperbilirubinemia are the basal ganglia, ocular movement nucleus, and acoustic nucleus of the brainstem.[1] Pathogenesis of bilirubin encephalopathy involves several factors, including the transport of bilirubin across the blood-brain barrier and into neurons.[1] Mild disruption results in left cognition impairment, while severe disruption results in ADCP.[1] Lesions caused by accumulation of bilirubin occur mainly in the global pallidus and hypothalamus.[1] Disruption of the blood-brain barrier by disease or a hypoxic ischemic injury can also contribute to an accumulation of bilirubin in the brain.[1] Bilirubin encephalopathy leading to cerebral palsy has been greatly reduced by effective monitoring and treatment for hyperbilirubinemia in preterm infants.[1] As kernicterus has decreased due to improvements in care, over the last 50 years the proportion of children developing athetoid CP has decreased.[8] In most cases, will have normal intelligence.

Movement and posture limitations are aspects of all CP types and as a result, CP has historically been diagnosed based on parental reporting of developmental motor delays such as failure to sit upright, reach for objects, crawl, stand, or walk at the appropriate age.[3] Diagnosis of ADCP is also based on clinical assessment used in conjunction with milestone reporting.[2] The majority of ADCP assessments now use the Gross Motor Function Classification System (GMFCS) or the International Classification of Functioning, Disability and Health (formerly the International Classification of Impairments Disease, and Handicaps), measures of motor impairment that are effective in assessing severe CP.[1][2] ADCP is typically characterized by an individual's inability to control their muscle tone, which is readily assessed via these classification systems.[1][2]

Magnetic resonance imaging (MRI) is used to detect morphological brain abnormalities associated with ADCP in patients that are either at risk for ADCP or have shown symptoms thereof.[4] The abnormalities chiefly associated with ADCP are lesions that appear in the basal ganglia.[4] The severity of the disease is proportional to the severity and extent of these abnormalities, and is typically greater when additional lesions appear elsewhere in the deep grey matter or white matter.[4] MRI also has the ability to detect brain malformation, periventricular leukomalacia (PVL), and areas affected by hypoxia-ischemia, all of which may play a role in the development of ADCP.[2] The MRI detection rate for ADCP is approximately 54.5%, however this statistic varies depending on the patient's age and the cause of the disease and has been reported to be significantly higher.[1]

Physical therapy and Occupational Therapy are staple treatments of ADCP. Physical therapy is initiated soon after diagnosis and typically focuses on trunk strength and maintaining posture.[1] Physical therapy helps to improve mobility, range of motion, functional ability, and quality of life. Specific exercises and activities prescribed by a therapist help to prevent muscles from deteriorating or becoming locked in position and help to improve coordination.[9] Occupational therapy interventions for children with CP emphasises function, and therapists assist with activities of daily living, such as feeding, dressing, bathing and toileting, grooming. Various areas of occupation are also considered, and the occupational therapist may assist the child with pencil grasp and handwriting skills and play. The occupational therapist makes use of everyday activities in order to reach a functional outcome.

Speech impairment is common in ADCP patients.[2][5] Speech therapy is the treatment of communication diseases, including disorders in speech production, pitch, intonation, respiration and respiratory disorders. Exercises advised by a speech therapist or speech-language pathologist help patients to improve oral motor skills, restore speech, improve listening skills, and use communication aids or sign language if necessary.[9]

Medications that impede the release of excitatory neurotransmitters have been used to control or prevent spasms.[10] Treatment with intrathecal baclofen, a gamma-aminobutyric acid (GABA) agonist, decreases muscle tone and has been shown to decrease the frequency of muscle spasms in ADCP patients.[10] Tetrabenazine, a drug commonly used in the treatment of Huntington's disease, has been shown to be effective treating chorea.[10]

Deep brain stimulation (DBS) is a technique that uses electrodes placed in the brain to modify brain activity by sending a constant electrical signal to the nearby nuclei.[10] Treatment of muscle tone issues via deep brain stimulation typically targets the global pallidus and has shown to significantly improve symptoms associated with ADCP.[10] The specific mechanism by which DBS affects ADCP is unclear.[10] DBS of the globus pallidus interna improves dystonia in people with dyskinetic CP in 40% of cases, perhaps due to variation in basal ganglia injuries.[11]