Introduction

The leading cause of childhood motor dysfunction is due to Cerebral Palsy, the most common neurological disease resulting in motor function deficiency. CP is a loss in the control of movement not from muscular disorders but from abnormal development of the brain or brain damage from a traumatic event. Due to a lesion on the corticospinal tract, most voluntary movements such as walking, are prevented. Most of the muscles are tight and rigid to passive stretch and usually result in the child flexing their elbow while clenching their fist. CP is a form of Upper Motor Neuron Syndrome that typically causes certain muscles to act in two ways. The lesion that occurs in an upper motor neuron first causes muscles to lose volitional command throughout the descending corticospinal tract. Secondly, at the same time, the child gains involuntary command creating an uncontrolled mixture of movements.The majority of CP cases occur during birth or during early childhood The Centers for Disease Control and Prevention has termed CP the most common motor disability in childhood with an average of 3.5 cases per 1,000 births. The most common cause of CP is from a lack of oxygen during the birthing process and brain deformities in the developing womb before and after birth.

Causes

CP can be caused by four different kinds of brain damage
  • Cerebral Dysgenesis
    • Categorized by abnormal brain development. It is characterized by a brain that does not develop, experiences incomplete division, and develops with incomplete motor organization
    • Risk factors that increase the likelihood of cerebral dysgenesis can be mutations in gene combinations, fever, and infections such as Rubella, Syphillis, and Herpes.
  • Intraventricular Hemorrhage (IVH)
    • Consists of arterial bleeding which results in a lack of oxygenated blood traveling back to the heart. Venous bleeding only affects the veins returning blood to the heart. It is most common in premature babies who have had respiratory issues or high blood pressure. Blood-clotting abnormalities, shaken baby syndrome, and pelvic inflammatory disease are all key risk factors for IVH.
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      Figure 1. Intraventricular Hemorrhage>>
  • Periventricular Leukomalacia (PVL)
    • Occurs when the white matter in the brain is damaged causing a decaying of the brain cells. This allows the filling of the lateral ventricles. The white matter in the brain, which transmits neurons back and forth between the gray matter, controls the synapse transmission involved in motor function. Without white matter, the myelin is damaged which further decelerates and hinders nerve transmission to allow proper movements to occur. Typically PVL occurs in the fetus between 26 and 34 weeks. Inflammation of umbilical cord, inflammation of fetal membranes, twin gestation, and vaginal bleeding are all common risk factors. Particularly decreased blood flow such as hypoxemia is a major cause for PVL.
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      Figure 2. Periventricular Leukomalacia
  • Hypoxic-Ischemic Encephalopathy (HIE)
    • This disease is characterized by a lack of oxygen to the brain. The brain tissue of a newborn can be damaged if asphyxia lasts for too long. Asphyxia can occur when the body is deprived of oxygen resulting in suffocation or even death. When a lesion occurs in the brain, there may be decreased blood flow to critical areas leading to a buildup of excitatory glutamate. This excess of glutamate can further create an overproduction and accumulation of toxic oxygen leading to cell death.
    • Current studies have been done regarding the treatment of HIE. Researchers have tested and proven that placing the asphyxiated newborn in a cool environment immediately following birth may significantly reduce the risks of HIE and other disabilities. The child must be placed within the first 6 hours after birth in order for negative effects to be reversed. Research is still being done on what the exact time frame is for this treatment to be successful.
    • This injury only effects full-term infants at 40 weeks. The more severe, the more detrimental the effect is on the child’s future activities and coordination of movements. Injury from umbilical cord, interruption in breathing, and blood containing less oxygen are all significant risk factors. Specifically, fetal stroke caused by blood-clotting abnormalities or blocked blood flow in the placenta increases the probability of HIE occurring. Children who live through asphyxia will eventually develop severe disabilities such as cerebral palsy and mental retardation.
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    Figure 3. Hypoxic Ischemic Encephalopathy

Signs of CP

There are 8 major signs of CP that help identify the disease from an early age. These include:
  • Muscle Tone
    • Hypotonia - decreased muscle tone
    • Hypertonia- increased muscle tone
    • Muscle spasms - involuntary contractions
  • Movement coordination and control
    • Spastic, Ataxic, and Mixed movements
    • Gait disturbances
  • Reflexes
    • Asymmetrical tonic reflex – head turning causes legs on ipsilateral side to extend, and the opposite limbs contract.
    • Symmetrical tonic neck reflex – when the neck is in extension, the child will maintain a crawling position.
    • Spinal gallant reflexes – the hips will respond and turn to the side of the body that is touched whenever the child is laying prone.
  • Posture
    • Landau reflex – assuming a lying position, the head in depression will cause the legs to drop, and as the head elevates, the legs will rise.
    • Parachute response – when the infant's head is prone to ground, they respond like they are landing on high impact to the ground with arms and legs extended out.
  • Balance
    • Uses both hands for support
    • Unable to sit without using hands for support
    • Sways when standing
    • Unsteady when walking
    • Difficulty making quick movements
  • Gross motor function
    • walking
    • standing
    • crawling
    • balancing
  • Fine motor function
    • Unable to hold objects/utensils for eating
    • Unable to hold pencils, or crayons for writing/coloring
    • Unable to turn pages in a book
  • Oral motor function
    • Apraxia- most common to CP, this speech impairment is caused by an inability of the brain to successfully send signals to oral muscles
    • Dysarthria- another speech impediment involving neurological underdevelopment that effect oral control
    • Other functions that are disabled include: closing the mouth, controlling tongue movement, and inability to contain saliva.

Classes of CP

There are two main categories of CP based on motor function which include spastic and nonspastic.
  • Pyramidal Spastic
    • This is the most common type of CP characterized by an increased and sustained amount of muscle tone during passive muscle lengthening mainly due the hyper excitability of the Ia afferent muscle activity.
    • The three main descending tracts that are responsible for increases muscle tone are the corticospinal, reticulospinal, and vestibulospinal tracts. Projections from corticospinal tracts
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      Figure 4. Lateral Descending Corticospinal Tract
      descend from the motor cortex and are responsible for voluntary movements in axial, limb, and cranial muscles.
      These neurons communicate the brain’s movement to the spinal cord. When these tracks are damaged, incorrect neuronal signals for continual contraction are sent to the muscles causing it to be stiff in flexed positions. Because of this, the signal from the motor cortex down to the spinal cord remains in a sustained excitatory state of increased tension.
    • Inside muscles are muscle spindles that contain intrafusal muscle fibers that signal change in muscle length and Ib afferent fibers originating in Golgi Tendon organs that sense muscle tension. Inside the intrafusal muscle fibers of muscle spindles are Ia afferents that have excitatory synapses onto the alpha motor neuron in the spinal cord. In the myotatic stretch reflex, the Ia afferent excites the alpha motor neuron in addition to an inhibitory interneuron in the spinal cord that inhibits the contraction of the antagonist muscle. This reflex helps the body in maintaining tone, posture, and balance by keeping a constant contraction of the flexors and inhibition of the extensors. When damage to the upper motor neurons originating from these tracks occur, there is a loss in inhibitory regulation controlling the muscles. If there is a lack of inhibition of these antagonistic muscles, the Ia afferent fiber input from the muscle spindles will increase and sustain its activity to the alpha motor neurons, increasing overall muscle tone which creates the hyper excitability of the spinal reflexes.
    • Another cause of spasticity are lesions that occur in the rostral medulla, damaging the descending reticulospinal tracts. This damage causes a change in the way the alpha motor neurons respond to painless stimuli by making it seem more painful than it is.The response is hyperactivity of the muscles even when the stimulus is painless.
    • Spastic CP can cause scoliosis, hip dislocation, and contracture of the limb muscles.

  • Extrapyramidal Non-Spastic
    • Damage to the extrapyramidal tract causes this form of CP which is characterized by fluctuating muscle tone. There are two types: ataxic and dyskinetic
      • Ataxic – poor balance
        • Involves fine motor skills such as writing and eating. Described as having shaky and uncoordinated movements causing the child to be imbalanced in space, which can further lead to irregular gait patterns.
        • The cause is damage to the cerebellum which originally is responsible for perfecting posture and coordination of movements
      • Dyskinetic
        • Characterized by damage to the basal ganglia which is responsible for relaying and processing messages between the cerebral cortex and the spinal cord to help regulate voluntary movement
        • Dyskinetic
          • Dystonia : twisting and repetitive movement
          • Athetosis: slow, continuous, rhythmic, involuntary movements
          • Chorea: irregular, unpredictable, abrupt movements
        • Athetoid –
          • involuntary writhing movement in arms, legs, and hands
  • Mixed Type
    • Combination of spastic and non-spastic CP that effects multiple areas of the brain including the basal ganglia and cerebellum.

Forms of Spastic CP

  • Hemiplegia: Rarely does it effect both sides of the child’s body. The child has a higher chance of developing scoliosis due to the shorter arm and leg length on one side. Typically walks on toes because of heel tightness
    • Acquired- disorder developed after birth up to 60 months of age
    • Congenital- The most common type of hemiplegia CP, this disorder occurs before or during birth. Causes could be stroke related or damage to the white matter. Children with premature brain damage are more likely to have psychological issues including severe mental and intellectual difficulties
  • Diplegia: involved both legs being affected. The muscles and tendons in the legs are normally hyperactive causing them to be tight and caving in towards midline.
  • Quadriplegia: involves all four limbs. Usually caused by significant brain damage. Walking and talking are very difficult for the child.
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    Figure 5. Types of Cerebral Palsy based on which limbs are affected

Quiz

  • 1. Which one of the following is not a sign of CP?
    • a. Sways when standing
    • b. Hypotonia
    • c. Inability to blink
    • d. Hyperextending legs and arms when lying prone
  • 2. What characterizes chorea?
    • a. involuntary writhing movement in arms, legs, and hands
    • b. irregular, unpredictable, abrupt movements
    • c. Involves fine motor skills such as writing and eating
    • d. twisting and repetitive movement
  • 3. What type of Cerebral Palsy irregular, unpredictable, abrupt movements
    • a. Ataxic
    • b. Athetoid
    • c. Dystonia
    • d. Chorea
  • 4. A three year old girl is diagnosed with CP. She is unable to separate both of her legs while walking. However, her arms can move freely about. What type of CP does she have?

    • a. Spastic Hemiplegiab.
    • b. Dyskinetic Dystonic
    • c. Spastic Diplegia
    • d. Dyskinetic Atheotoid

  • 5. Which of the following are associated with Periventricular Leukomalacia?
    • a. The white matter in the brain is damaged causing a decaying of the brain cells.
    • b. Arterial bleeding which results in a lack of oxygenated blood traveling back to the heart.
    • c. A brain that does not develop, experiences incomplete division, and develops with incomplete motor organization.
    • d. A lack of oxygen to the brain
  • 6. True or False: Placing a newborn in a hypothermic environment immediately decreases the risk of Hypoxic-Ischemic Encephalopathy
  • 7. True or False: Spasticity is caused by an increase in the Ia afferent activity to the spinal cord regulating the flexor muscle activity and a decrease in the inhibitory interneuron activity to the antagonistic muscles
  • 8. Which of the following characterizes fine motor function?
    • a. Unable to hold objects/utensils for eating
    • b. Unsteady when walking
    • c. Crawling
    • d. Difficulty making quick movements
  • 9. What is a common risk factor for Cerebral Dysgenesis?
    • a. Inflammation of umbilical cord
    • b. Blood-clotting abnormalities
    • c. Shaken Baby Syndrome
    • d. Mutations in gene combinations
  • References

  • Allison Brashear, M., & Elie Elovic, M. (2010). Spasticity : Diagnosis and Management. New York: Demos Medical.
  • "Cause of Cerebral Palsy." My Child at Cerebral Palsy.org: The Ultimate Resource for Everything Cerebral Palsy. N.p., n.d. Web. http://cerebralpalsy.org/about-cerebral-palsy/cause/
  • Centers for Disease Control and Prevention. Data and Statistics for Cerebral Palsy. [July 31, 2015]; http://www.cdc.gov/nchs/births.htm.
  • Dyskinetic Cerebral Palsy." Cerebral Palsy Alliance. N.p., n.d. Web. <https://www.cerebralpalsy.org.au/what-is-cerebral-palsy/types-of-cerebral-palsy/dyskinetic-cerebral-palsy/>.
  • Howlin, P., & Udwin, O. (2002). Outcomes in Neurodevelopmental and Genetic Disorders. Cambridge: Cambridge University Press.
  • Mukherjee, Angshuman, and Ambar Chakravarty. "Spasticity Mechanisms – for the Clinician." Frontiers in Neurology. Frontiers Research Foundation, n.d. Web. 8 Dec. 2015. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3009478/>.
  • National Institute of Neurological Disorders and Stroke. Cerebral Palsy: Hope Through Research. NIH Publication Number 10-159, updated 5/6/10; http://www.ninds.nih.gov/disorders/cerebral_palsy/detail_cerebral_palsy.htm
  • Pia Wintermark, “Current Controversies in Newer Therapies to Treat Birth Asphyxia,” International Journal of Pediatrics, vol. 2011, Article ID 848413, 5 pages, 2011. doi:10.1155/2011/848413
  • Images

  • Quiz Answers

    • 1. c.
    • 2. b
    • 3. d
    • 4. c
    • 5. a
    • 6. true
    • 7. true
    • 8. a
    • 9. d