causes of Cerebral palsy and its newest treatment

Cerebral palsy

Definition and prevalence:-

Cerebral palsy is the commonest cause of severe neurological disability in chilclren (2-3 per 1000 live births) and has slightly increased in recent years partially explained by the reduced mortality of LBW infants with an increased rate of CP in survivors.

                Cerebral palsy is a general term given to a variety of conditions with different aetiologies. They all lead to non-progressive damage to the developing brain (under 4 years of age), which affects the motor system. Although the cerebral lesion is static, manifestations change as the condition evolves in each individual. There are often associated problems of vision, hearing, sensation and intelligence.

Aetiology

I- Preterm babies:-

Around 40% of children with CP have been prematurely born. The aetiology is Perinatal in 90% of these cases:

Periventricular leukomalacia: This is due to hypoperfusion-infarction in the watershed areas of the preterm brain wich cannot compensate for hypotension by means of autoregulation. The internal capsule is mainly affected, starting with immediate Periventricular areas affecting the legs.

Intraventricular haemorrhage: The germinal matrix around the lateral ventricles in preterm infants is well vascularised and susceptible to bleeding. CP only results if there is associated ventricular dilatation or parenchymal haemorrhage, the latter probably due to venous obstruction.

A few children with CP who are born prematurely have a prenatal cause e.g. brain malformation (10%).

II- Term infants:-

                In these children the aetiology is prenatal in the majority of cases (75%).

•          Genetic:- Especially ataxic type.

•          Cerebral malformation: mainly cortical dysplasias due to migrational defects e.g. polymicrogyria or pachygeria.

•          Intrauterine infections: CMV, rubella, toxoplasmosis.

•          Maternal-placental illness: causes cerebrovascular disease in the fetus, mainly Periventricular leukomalacia and unilateral / bilateral middle cerebral artery infarction.

•          15% are of Perinatal origin e.g. birth asphyxia and neonatal jaundice (Now is rare).

•          10% postnatal mainly meningitis, cardio-respiratory arrest and trauma due to accidental or NAI.

      Perinatal asphyxia and CP

•                          Intrapartum asphyxia is overdiagnosed as a cause of CP, however intrapartum asphyxia to cause CP it must produce encephalopathy at least moderate degree.

•               Intrapartum asphyxia is not diagnosed by low apgar score alone but also needs manifestations of acidosis-encephalopathy and end ogens dysfunction.

•                 Table 1. American Academy of Pediatrics / American College of Obstetrics and Gynecology (1992)

•          Profound metabolic acidosis    (pH<7.0).

•          Apgar 3 or lower beyond 5 minutes.

•           Neonatal encephalopathy.

•            Multiorgan system dysfunction.

   Table 2. international cerebral Palsy Task Force (1999)

•          EssentialModerate to severe neonatal encephalopathy.

•             pH<7.0

•          Severe fetal heart rate changes.

•          Apgar lower than 6 beyond 5 minutes.

•          Multisystem dysfunction

•          Evidence of acute cerebral involvement (electroencephalography/imaging)

•         

Table 3. American College of Obstetrics and

 Gynecology (2002)

•          Asphyxia pH<7.0.

•          base deficit> 12mmol/L.

•          Moderate to severe neonatal encephalopathy.

•          Fetal heart rate changes: bradycardia, loss of variability.

•          Apgar 3 or lower beyond 5 minutes.

•          Multisystem involvement.

•          Early imaging changes.

•          Table:4 Neonatal Encephalopathy

•          Mild IncreasedirritabilityHyperexcitabilityJitterinessExaggerated Moro and tendon reflexesSympathetic overreactivityTransient changes in tone (<6 hours)

•          Moderate

•          LethargyHyotoniaDiminished reflexesWith or without associated seizures

•          Severe

•          Profound obtundation/coma,Flaccid muscle tone,Brainstem dysfunction,Apnea,Skew deviation, nystagmus, sucking and swallowing abnormalities,Increased intracranial tension,Seizures (frequently/ refractory )

The following relationships between intrapartum asphyxia, neonatal encephalopathy and cerebral palsy as follow:-

1. Some children with neonatal encephalopathy will have intrapartum asphyxia.
2. All children with intrapartum asphyxia will have neonatal encephalopathy.
3. Some children with intrapartum asphyxia will develop later CP.
4. Some children with neonatal encephalopathy and no intrapartum asphyxia will develop later CP.
5. Some children with later CP will have had previous neonatal encephalopathy and no intrapartum asphyxia (Note that 4 and 5 are equivalent statements.)•                 

•                                     Neonatal encephalopathy have many causes one of them is Intrapartum asphyxia but most of them are intrauterine events and if associated with low apgar score it is a result and not a cause of neonatal encephalopathy: Causes include SGA, maternal fever, viral illness, placental abnormalities severe preeclempsia but the commonest cause remain idiopathic.

•          Most  children with later CP will not have previous intrapartum asphyxia.

•          Most  children with later CP will not have previous neonatal encephalopathy.

•          All children with later CP will have a neurodevelopmental disability.

•          Some children with a later non-CP neurodevelopmental disability will have had previous intrapartum asphyxia.

•          Some children with a later non-CP neurodevelopmental disability will have had previous neonatal encephalopathy but no  intrapartum asphyxia.

•          Most  children with a later non-CP neurodevelopmental disability will not have had previous neonatal encephalopathy.

•          Some normal children will have had previous intrapartum asphyxia.

•          Some normal children will have had previous neonatal encephalopathy but no intrapartum asphyxia.

•          Neurophysiology of CP

•          Damage to the extrapyramidal system results in dyskinetic CP(Basal ganglia) or ataxic CP (cerebellum). Spastic CP results from damage to pyramidal system (Motor cortex and internal capsule) this system is responsible for voluntary movements and learning motor patterns which are then transferred to the extrapyramidal system for later use.

•          Damage to the pyramidal system cause the following problems:-

•          Loss of selective voluntary control.

•          Dependence on primitive patterns of mobility.

•          Abnormal muscle tone (Hypotonia or spasticity) and muscle weakness.

•          Agonist / antagonist imbalance with predominance of hip adductors, flexors and internal rotators, knee flexors (Hamstrings) and ankle planter flexors (gastrocnemius and soleus). This cause fixed joint positions and eventually muscle contractures.

•          Ppreserved primitive reflexes mainly due to lack of inhibitory effect on the vestibular and brainstem nuclei.

•          CLASSIFICATION OF CP 

•          The Swedish classification is usually used as it is simple and practical. The following CP syndromes may be combined and each child must be individually described.

•          A standardized recording form may be used for this purpose

Diplegia (44%)

•          Spasticity affects mainly the lower limbs with variable but lesser involvement of upper limbs. 65% occurs in preterm infants due to perinatal cerebrovascular disease. Almost all are home or limited outside walkers

•          Quadriplegia (7%)

•          Severe spasticity of all limbs, usually worse in the upper limbs. In preterm infants, the main cause is perinatal cerebrovascular disease. In term infants causes include prenatal cerebrovascular disease, severe birth asphyxia and congenital infection. Disability is severe, most being non-mobile and severely mentally retarded. Feeding problems are common due to bulbar involvement, as is a tendency to hip dislocation, scoliosis, constipation .

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•           

•          Hemiplegia (34%)

•          Spasticity affects one half of the body, usually with the arm worse than the leg but sometimes vice versa. 20% are preterm, usually unilateral cerebrovascular disease and 80% term due to unilateral prenatal cerebrovascular disease (PVL or infarction of main cerebral artery) or cerebral malformation. Walking is usually only slightly delayed.

•          Dyskinetic CP (9%)

•          Mainly athetoid, some dystonic (rigid or variable tone). Mobility is variable. Dyskinesia is often a feature of mixed CP, usually due to asphyxia. (A short period of asphyxia in the term infant leads to athetosis but normal IQ due to damage to basal ganglia alone). Choreo-athetosis due to kernicterus is now rare.

•          Ataxic CP (6%)

•          Most of these infants are born at term of which half are due to genetic conditions, mainly autosomal recessive. Some have cerebellar hypoplasia demonstrable on CT/MRI scan which can be associated with particular syndromes e.g. Joubert’s ataxic diplegia is often seen.

•          DIAGNOSIS OF CP

•          CP is diagnosed on careful follow-up of at risk infants from the neonatal unit in about half of cases. The rest present because of parental concern and from routine paediatric surveillance, or will acquire CP from a later severe illness, usually in the first year.

•          Risk assessment for CP on the neonatal unit

•          *Investigation

•          Serial ultrasound in the neonatal period is essential for all infants with significant problems. PVL with later cystic change is associated with CP in 59% and IVH with ventricular dilatation in 48%.

•           Brain MRI after screening ultrasound identifies cerebral lesions even more accurately.