Cerebral Palsy : Introduction and classification

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Cerebral Palsy (CP) is an umbrella term used for static or non-progressive disorders of the foetal or infant brain affecting the development of movement, posture and co-ordination resulting from a lesion of an immature brain. It is one of the common chronic neurological disorders in children. The incidence of cerebral palsy is in the region of 2.5 per 1000 live births and has always varied from one country to another.

 

The causes of cerebral palsy can be generally classified as prenatal, perinatal and postnatal causes. 

• The prenatal causes include genetic factors, intrauterine infection during pregnancy, radiation, cerebral infarction, metabolic and toxic factors and hypoxia. 
• The perinatal risk factor of birth asphyxia is a well-recognised cause of cerebral palsy particularly in the term baby, the incidence of birth asphyxia among cases of cerebral palsy is declining. 
• Postnatal causes of cerebral palsy include hypoglycaemia, hyperbilirubinaemia, meningitis, subdural haematoma, acute infantile hemiplaegia and trauma.

Approximately half of all the cases of cerebral palsy are associated with preterm delivery and low birth weight. The main pathological lesions found in preterm infants who later develop cerebral palsy are periventricular leukomalacia and intracerebral haemorrhage. Lesions in the full term infants who develop cerebral palsy are mainly due to hypoxic ischaemic encephalopathy and are seen in thalami and basal ganglia or in the cortex and sub-cortical white matter.

Various Comorbidities of CP child :

1. Musculoskeletal disorders and deformities develops later when the child is not treated at the earlier stage, when the symptoms are not severe. Common joint deformities are ankle equinovarus, knee and hip flexion, lumbar spine kyphosis, 
2. Children in GMFCS level V have been demonstrated to have a greater risk for high myopia, absence of any fusion, dyskinetic strabismus, more severe gaze dysfunction, optic neuropathy, and cerebral visual impairment, nystagmus (reflexive back and forth movement of eye when head moves).
3. Hearing problems occur in approximately 30% to 40% of children with CP. Hearing loss is known to be especially prevalent in children with CP with kernicterus, congenital infections, low birth weight, or severe hypoxic ischemic injury. Conductive and sensori-neural impairments are found in children with CP, who should be screened by an audiologist.
4. Oral motor impairments namely problems with feeding, swallowing, drooling is present. Gastroesophageal reflux disease (GERD) is common among CP. Poor oromotor skills, gastroesophageal reflux, and the inability to self-feed or communicate hunger can all increase the risk for malnutrition in children with CP. 
5. Speech impairments are common in child with CP. They have difficulty in controlling the oral muscles used for speech (lips, tongue, vocal folds, diaphragm, facial muscles), dysarthria (difficulty pronouncing or articulating words), apraxia of speech.
6. Cognitive and intellectual impairments : Cognitive deficits tend to be most prevalent and severe in those with spastic tetraplegia, although children with spastic tetraplegia may have normal to near-normal intelligence. Aphasia associated with poor language development. Functionally looks as though the person has difficulty comprehending the meaning of certain words. Assessment of intellectual functioning can be difficult in patients with severe motor and communication difficulties, which may lead to an underestimation of cognitive function. The overall frequency of mental retardation, defined as an IQ score of 69 or below, is reported to be 50% to 70%. In general, patients with more severe neuromuscular impairments are at greater risk for cognitive impairments, but some patients with severe motor impairments can have normal cognition.
7. Epilepsy is common in individuals with CP. It is particularly common in those with tetraplegic CP and in those with hemiplegic CP. Partial epilepsy is the most common form of seizure activity in all children with CP, and is especially common in children with hemiplegia who have seizures with a prevalence of around 70% in this specific population. Generalized tonic-clonic seizures are more common in those individuals with spastic tetraplegia and diplegia.
8. A wide variety of behavior and emotional disorders are possible, including attention deficit disorder, passivity, immaturity, anger, sadness, impulsivity, emotional lability, low self-esteem, and anxiety. Difficulty with peer relationships has been found even in children with milder CP (GMFCS I). Compared to their classmates, children with mild CP were found to have fewer reciprocated friendships, fewer sociable and leadership behaviors, and were more isolated and victimized by their classmates. 
9. Decreased bone mineral density (BMD) and increased risk of fracture with minimal trauma is common in patients with moderate to severe CP, especially those who are nonambulatory. By the age of 10 years, most nonambulatory children have osteopenia, as defined by BMD z score of <–2.0 in their femur.

Fig : Phenotypical appearance of different CP child

Classification of cerebral palsy

Cerebral palsy may be classified in terms of physiological, topographical, aetiological and functional categories : 

Clinical features of CP based on physiologic classification :

SPASTIC CEREBRAL PALSY: 

This group shows the features of upper motor neuron type of pyramidal tract lesion such as spastic hypertonicity, exaggerated deep tendon reflexes, ankle clonus and extensor plantar response. It may be symmetric or asymmetric and may involve one or more extremities. 

• Spasticity refers to increased muscle tone.
• Depending upon the grade of spasticity, the child may show severe to moderate to mild symptoms. Symptoms includes :
• Hypertonus with little change in the degree of tone.
• Increased tone or constant co-contractions of the agonist and antagonist muscle which inhibits any type of relaxation when awake or asleep.
• Child is vulnerable to development of deformities in spine, upper-limbs and lower-limbs joints
• To perform any activity, the child attempts to move the limbs with much efforts. In case of severe spasticity, the limbs have very little or no voluntary movement but stimulus of primitive reflex causes reflex responses.

1) Spastic diplegia : the lower limbs are affected more than the upper limbs. Some children go through an initial hypotonic or dystonic phase and then a spastic phase. Particularly the preterm babies are affected but the term babies with perinatal asphyxia are also prone. The spastic phase of diplegia can manifest in two types : 

• The extensor muscles such as triceps and quadriceps shows 'phasic spasticity'. The phasically spastic muscles show brisk tendon reflexes and often the clasp-knife phenomenon. 
• The flexor muscles are mainly affected in 'tonic spasticity'. Tonically spastic muscles show decreased lengthening reaction and rapidly develop contractures. 
• The hip flexors, hamstrings and calf muscles together with adductors of hip form the main tonic groups in the lower limbs, causing the child to be flexed at hip, knee and in equinus at the ankle with the legs usually internally rotated and the characteristic scissoring posture.
• The upper limbs are flexed at elbow and wrist, and the fingers are flexed across the adducted thumb with marked spasticity of the pronators. Atrophy below the waist occurs in many patients. 

In spastic diplegia of low birth weight babies epilepsy is uncommon and intelligence is only moderately reduced whereas in diplegia of term asphyxiated babies, epilepsy, mental retardation, microcephaly, speech and behaviour disorders are more common. The most common neuropathologic finding in spastic diplegic cerebral palsy is periventricular leukomalacia (PVL), which occurs when the periventricular structures are vulnerable between 26 weeks and 36 weeks gestation, usually in utero.

2) Spastic Quadriplegia : This is the most severe form of cerebral palsy with marked motor impairments of all 4 extremities. Child has difficulties with feeding (due to pseudobulbar palsy), increase gastroesophageal reflux and risk of aspirations, speech and visual abnormalities. There is a high association with mental retardation and seizures. Neuropathologic findings include severe periventricular leukomalacia, multicystic encephalomalacia and cerebral dysgenesis. Positional deformities are common resulting in windswept posture of lower limbs, dislocation of hip, pelvic tilt, scoliosis and rib deformities.

3) Spastic Hemiplegia : This type of cerebral palsy affects one side of the body. The majority are congenital and the result of maldevelopment, prenatal circulatory disturbances or perinatal stroke in the distribution of middle cerebral artery. Postnatal causes include acute CNS infection, acute infantile hemiplaegia, cerebral thrombosis particularly in congenital cyanotic heart disease and subdural haematoma. The right side is more often affected than the left and the arm more severely than the leg. Neuropathologic findings show an atrophic cerebral hemisphere or a porencephalic cyst. Spastic hemiplegic CP child show features like: 

• Children usually present in the second half of first year with asymmetric crawling, tip toeing on the affected side while walking, asymmetric hand skills, persistence of fisting of the affected side or unusual dominance of the unaffected side.
• The child walks with a circumduction gait with the affected upper limb adducted at shoulder, flexed at elbow and wrist, with forearm pronated and the lower limb partially flexed and adducted at hip, the knee flexed and the foot in equinus position. 
• There is growth arrest of the affected extremities, particularly the hands and the feet. 
• Cortical sensory loss and haemianopia are not infrequent. Convulsions and mental retardation are seen in about one-fourth of these children. 
• Children with right hemiplegia also have a delay in acquiring language skills and speech. 

DYSKINETIC CEREBRAL PALSY: 

This type of cerebral palsy results from damage to the extrapyramidal system usually the result of neonatal jaundice or acute severe perinatal asphyxia. Pathologic findings include lesions in the globus pallidus, subthalamic nucleus and status marmoratus (lesions in the basal ganglia and thalamus with a marbled appearance). There is defect of posture and involuntary movement in the form of athetosis, choreoathetosis, rigidity or dystonia. 

1) Athetosis : Athetosis is characterized by slow, continuous, involuntary, writhing movements that are present at rest and made worse by attempts to move. The involuntary movements usually affect the hands, feet, arms and legs. 

The affected infants go through an early hypotonic phase characterised by lethargy, poor head control and feeding difficulty. This is followed after 4 months of age by the dystonic phase associated with extensor hypertonia, arching attacks, mass body movements and abnormal persistence of primitive reflexes. The stage of involuntary movement is obvious after 2 years consisting of slow writhing distal movements. When athetosis is caused by kernicterus there is often an associated high-tone deafness. Child show following features:

• Athetosis refers to fluctuating muscle tone. The child's tone may fluctuate from stiff body (hypertonia) to floppy body (hypotonia).
• Due to tonal fluctuations there is no adequate co-contractions of the proximal and distal joints, which is necessary for stability, mobility and postural control.
• The child is dysarthric and drooling may be prominent. Seizures are uncommon and intelligence may be well preserved, but difficult to be quantified by the routine intelligence tests. 
• Athetoid cerebral palsy makes it difficult to hold onto an object, like a pencil or cutlery, due to fluctuating muscle tone. A person with athetosis may experience difficulties with eating and drinking.
• Athetosis can be divided into following types namely a)Athetosis with spasticity, b)Athetosis with tonic spasm, c)Pure Athetosis. Both a) and b) type of athetoid CP shows dystonic features.

2) Choreoathetosis : In this type, the writhing athetotic movements have in addition jerky, irregular, unpredictable or dance-like rapid movements involving the proximal extremities and face. Stress and excitement may exacerbate the chorea.

• The individual has muscle tone which fluctuates between hypotonia to normal and hypotonia to hypertonia.
• Movements can affect various body parts and interfere with movement, speech and swallowing. 
• There is no co-contractions and deformities are rare but there is tendency of subluxation of the shoulder and finger joints. 
• There is lack of selective movements and fixation of movement
• Primitive spinal patterns are present but modified by athetosis. There are intermittent tonic reflex pattern.
• Righting reactions and equilibrium reactions are present to some extent but coordination in abnormal. Protective extension of the arms in abnormal and often absent.
• Child shows similar features like that of athetoid CP but the involuntary movements can be of more amplitude due to proximal muscles involvement. Child has difficulties with ADL performance, oro-motor dysfunction (drooling, grimacing)

3) Dystonia : This type affects the trunk and proximal muscles of the limbs and consists of abnormal twisting and sustained movements, which may be either slow or rapid. These children tend to be more severely affected. Child with dystonia may show following features :

• It impede motor function through involuntary muscle contractions and limitations in muscle relaxation. 
• Dystonic postures can be painful, interfere with sleep, interfere with positioning for sitting and lying. If dystonia involves neck and/or facial muscles then difficulties with oro-motor functions are seen like speaking, swallowing, eating, chewing.
• Dystonia can result in high energy expenditure and malnutrition. Dystonic postures/hypertonia can create challenges for the child to perform his personal hygiene and other basic ADL. Child's parent also faces challenges with care-giving.

Hyperkinetic/Dyskinetic CP patients experience involuntary movements like jerky (chorea, athetosis) and non-jerky (dystonia) which causes incoordination between bilateral sides of body, excessive effort and energy is needed to control or stop unnecessary movements while performing any activity. Patients has to put continuous conscious attention to complete task thus causing cognitive overload. In dystonia, patients experience slowness in upper-limb and lower-limb functional movements while doing any activities due to dystonic sustained contractions. Ataxic CP patients experience imbalance, postural instability, eye-hand incoordination and incoordination of upper-limbs and lower-limbs which  negatively impacts their daily occupational functioning due to slowness and excess energy expenditure for controlling movements, balance and prevent themselves from falling.

ATAXIC CEREBRAL PLASY  :

In a small proportion of children with cerebral palsy, the clinical manifestations indicate a cerebellar defect, e.g. ataxic reeling gait, intention tremor, past pointing, dysdiadochokinesia, affected finger-nose and heel-knee test and muscular hypotonia. Most of these cases are congenital in origin and due to malformations of the cerebellum and may have an autosomal inheritance. A few cases are due to perinatal asphyxia and hydrocephalus. 

• Most patients have congenital hypotonia. It  is characterized by moderate to severe muscular hypotonia.
• Truncal ataxia predominates over appendicular signs. Child shows generalized weakness, incoordinated movements and intentional tremors. Ataxia may be associated with spasticity, athetosis or combination of both.
• Child show imbalance while walking, fear of fall is present, wide base of support while standing and walking. Childs has difficulty in performing gross-motor and fine-motor ADL activities. They require help from their parents to complete the task.
• Motor milestones and language skills are typically delayed.

HYPOTONIC CEREBRAL PLASY

In a few children cerebral palsy takes the form of a hypotonic quadriplaegia without any spasticity. Many infants destined to develop typical spastic diplegic or choreoathetoid cerebral palsy pass through a hypotonic phase and require continued observation for a definitive diagnosis. In hypotonic cerebral palsy, there has often been perinatal asphyxia and is associated with learning difficulties. Hypotonic CP shows following features : 

• Muscle tone may be too low that tonic neck reflex is not elicited. The child has full range of motion but shows less muscle activity and gross-motor movements compared to normal child.
• There may be hypermobility of the joints but there is no ability to co-contract muscles. Typically the legs go in the frog position i.e. hip abduction and external rotation and knee flexion. This position may cause hip dislocation. Their head lag when are held up in 'pull to sit' position. 
• Form 'inverted U' shape in ventral suspension position. In vertical suspension, the legs are extended passively. Due to decreased tone of the shoulder girdle muscles, the child slips through the examiner's hand when held in vertical suspension position.
• The child appears to be weak with flat chest and trunk. Respiration is usually shallow. Poor ability to cough and clear airway secretions.

Fig : Hypotonic CP : A)Headlag evident on 'pull to sit' position, B)Scarf sign (Elbow crosses midline), C)Child slips from examiner's hand in vertical suspension, D) Inverted U shape on body in horizontal suspension

Mixed Cerebral Palsy : 

Mixed cerebral palsy includes manifestations of two or more types usually of both spastic and extrapyramidal types. Often an ataxic component is present. These patterns of motor impairment are the result of involvement of large areas of brain affecting the cortex, subcortical areas and basal ganglia.

Assessment using specific scales: Severity of the CP condition can be assessed using 

• Gross Motor Function Classification System (GMFCS) for gross motor function.
• Manual Ability Classification System (MACS) for hand function abilities.
• Communication Function Classification System (CFCS) to assess effectiveness of communication between CP child (sender person) and receiver person of information. 
• The Pediatric Functional Independence Measure (WeeFIM) was developed to measure the functional independence of children with disabilities.  WeeFIM was designed to measure the need for aid and the severity of the disability in children aged between 6 months and 7 years.
• The Activities Scale for Kids (ASK) is an instrument that assesses and monitors functional changes in children of 5 to 15 years with physical limitations caused by musculoskeletal disorders.
• The Children’s Assessment of Participation and Enjoyment (CAPE) and Preferences for Activities in Children (PAC) are instruments developed together to evaluate the nature of participation and the effectiveness of interventions aimed at increasing such participation (social and community). It was developed for children from 6 to 21 years old.
• The Pediatric Balance scale, a modification of the Berg Balance Scale, can be used to measure the functional balance (which includes static and dynamic balance) for school-aged children.

Thankyou for reading !!!

Dr.Sheetal Tatar-Dhande, Dr.Ashwini Sangar, Dr.Pallavi Khadse-Kolhe.