Each year in the United States one child out of approximately two hundred and seventy-eight will be diagnosed with Cerebral Palsy. This disability is the leading neurodevelopmental motor impairment today. Cerebral Palsy (cerebral refers to the brain and palsy refers to the loss or impairment of motor function), commonly referred to as CP, is a overarching term that is described by a loss or impairment of motor function and can involve nervous system functions such as learning, seeing, hearing and thinking. The damage affects the cerebral cortex of the brain, which is involved in the production of movement and integration of sensory signals. If damage occurs before or during birth (85-90% of the time) it is referred to as congenital CP. It can also occur soon after the birth; the important thing to note is that the damage is done while the brain is still developing. If the damage occurs more then 28 days after birth by injury or infection it is called acquired CP. The good news is that the damage is non-progressive. Unfortunately, it is near impossible to repair and the problems, or disabilities, that the child faces will last for the rest of their life.
In many cases the cause of cerebral palsy is unknown, it could be due to meningitis (infection of the cerebral spinal fluid), encephalitis (inflammation within the brain region), physical injury such as an accident, blood flow restrictions, genetic abnormalities, congenital deformations or maternal infection. It is classified by either the type of movement disability or by the limbs that it affects.
Classification of CP by number of limbs involved
Classification of CP by number of limbs involved


Classifications of Cerebral Palsy:

It has many different types, four based on how the movement is affected are:

  • Spastic - (Hypertonia) Increased muscle tone. Damage to the Motor Cortex or Corticospinal tract
  • Ataxic - Problems with coordination and balance. Damage to the Cerebellum
  • Dyskinetic - Muscle tone varies from being set too tight to being set too lax. Damage to the Basal Ganglia
  • Mixed - Symptoms from multiple types of CP - Most common is a combination of Dyskinetic & Spastic. Damage to the Basal Ganglia, Cortex and Cerebellum

Classifications based upon the limbs affected according to the Ontario Federation for Cerebral Palsy:
  • Hemiplegia - One hemisphere of the body is impaired. Arm tends to be more affected
  • Diplegia - All four limbs affected. The legs show increased impairment
  • Quadriplegia - All four limbs are impaired
  • Monoplegia - One limb (usually an arm) is impaired
  • Triplegia - Three limbs are affected. Generally, it is two arms and a leg

The classification of the movement disorder and affected limbs are usually combined. For example an individual may have spastic hemiplegia.


Brain Damage:

According to the National Institute of Neurological Disorders and Stroke some possible forms of brain damage that can cause its novel symptoms are:

Perventricular leukomalacia (PVL) - Damage to the white matter of the brain.
The white matter of the brain is responsible for transmitting signals inside the brain and to the rest of the body. Damage from PVL looks like tiny holes in the white matter of an infant’s brain. These gaps in brain tissue interfere with the normal transmission of signals. Researchers have identified a period of selective vulnerability in the developing fetal brain, a period of time between 26 and 34 weeks of gestation, in which periventricular white matter is particularly sensitive to insults and injury.

Cerebral dysgenesis - Abnormal developement of the brain
Any interruption of the normal process of brain growth during fetal development can cause brain malformations that interfere with the transmission of brain signals. Mutations in the genes that control brain development during this early period can keep the brain from developing normally. Infections, fevers, trauma, or other conditions that cause unhealthy conditions in the womb also put an unborn baby’s nervous system at risk.

Intracranial hemorrhage - Bleeding in the brain
Bleeding inside the brain from blocked or broken blood vessels is commonly caused by fetal stroke. Some babies suffer a stroke while still in the womb because of blood clots in the placenta that block blood flow in the brain. Other types of fetal stroke are caused by malformed or weak blood vessels in the brain or by blood-clotting abnormalities. Maternal high blood pressure (hypertension) is a common medical disorder during pregnancy and is more common in babies with fetal stroke. Maternal infection, especially pelvic inflammatory disease, has also been shown to increase the risk of fetal stroke.

Asphyxia - Sever lack of oxygen in the brain
A lack of oxygen in the brain caused by an interruption in breathing or poor oxygen supply, is common for a brief period of time in babies due to the stress of labor and delivery. If the supply of oxygen is cut off or
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Table 3
reduced for lengthy periods, an infant can develop a type of brain damage called hypoxic-ischemic encephalopathy, which destroys tissue in the cerebral motor cortex and other areas of the brain. This kind of damage can also be caused by severe maternal low blood pressure, rupture of the uterus, detachment of the placenta, or problems involving the umbilical cord, or severe trauma to the head during labor and delivery.

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Table 1
General Symptoms & Diagnosis:

Symptoms include but are not limited to
  • Ataxia - lack of muscle coordination when performing movements voluntarily
  • Spasticity - exaggerated reflexes and stiff or tight muscles
  • Weakness in one or more appendage (arm or leg)
  • Variations in muscle tone, being too lax or too tense
  • Walking on toes, a crouched gait, or a "scissored" gait
  • Excessive drooling or problems with swallowing or speaking
  • Tremors - shaking or involuntary movements at random
  • Difficulty with precise everyday movements
  • Delays in achieving motor skills

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Table 2

Spastic Cerebral Palsy:

Coronal and lateral views of the lower limbs of a 7-year-old boy with bilateral spastic cerebral palsy.

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Importance of Spinal Interneurons

According to the St. Louis Hospital's Center for Cerebral Palsy Spasticity, the term "spasticity refers to increased tone, or tension, in a muscle. Normally, muscles must have enough tone to maintain posture or
movement against the force of gravity while at the same time providing flexibility and speed of movement. The command to tense, or increase muscle tone, goes to the spinal cord via nerves from the muscle itself. Since these nerves tell the spinal cord just how much tone the muscle has, they are called "sensory nerve fibers." The command to be flexible, or reduce muscle tone, comes to the spinal cord from nerves in the brain. These two commands must be well coordinated in the spinal cord for muscles to work smoothly and easily while maintaining strength."

The muscle sends these signals regarding the state of the muscle to the spinal cord by the muscle spindle and golgi tendon organ sensors through afferent type Ia and II axons. When damage to the brain occurs it is still unclear why it affects the areas that control muscle tone and specifically the tone of the appendages (arms and legs) primarily, but it does. As a result the cortex is inefficient in controlling how much flexibility a limb has via descending inhibitory nerves which synapse on the spinal interneurons. This causes the excitation signals from the muscle to dominate the interneurons in the spinal cord which results in an increased excitation of the muscles, causing them to be continually in a state of increased tension, or spastic. Spastic Cerebral Palsy is normally associated with the diplegic, hemiplegic and quadraplegic forms of the disorder and approximately 80% of all cases of CP involve some form of spasticity. Unfortunately the constant increased tension on the muscles causes side effects which include inhibition of voluntary movement, protein synthesis in muscle cells, and longitudinal muscle growth. It will also cause minor to major muscle and joint deformities over periods of time and limited stretching capability in normal everyday activities.

The region specificity of the different "-plegias" is probably due to the somatopic arrangement of the supraspinal structures. Damage to a specific region would affect the cortex's ability to manipulate that specific limb or limbs. This is also true of the cerebellum in regards to ataxic CP as the vermis and the intermediate regions are also somatotopically organized.

Quiz Questions:

1) Ataxic Cerebral Palsy deals with:
a) Muscle tone varies from being set too tight to being set too lax. Possible damage to the Basal Ganglia and Motor Cortex
b) Symptoms from multiple types of CP - Most common is a combination of Dyskinetic & Spastic. Damage to the Basal Ganglia, Cortex and Cerebellum
c) Problems with coordination and balance. Damage to the Cerebellum
d) (Hypertonia) Increased muscle tone. Damage to the Motor Cortex or Corticospinal tract

2) Intracranial hemorrhage is due to:
a) Damage to the white matter of the brain.
b) Bleeding in the brain
c) Abnormal developement of the brain
d) Severe lack of oxygen in the brain

3) A quadraplegic is impaired in all four of their limbs.
True or False?

4) When a person has persistent increased muscle tone in one or more limbs they have Dyskinetic Cerebral Palsy.
True or False?

5) Spastic Cerebral Palsy is caused by too much excitation, of the muscles, from the motor cortex.
True or False?

Answers: 1: c) Ataxia refers to problems with balance and coordination 2: b) most likely caused by a fetal stroke 3: True. A quadraplegic involves all four of the limbs with the disorder 4: False. They have Spastic Cerebral Palsy 5: False. The excitation stems from a polysynaptic reflex loop that comes the muscle itself. The brain isn't actually providing enough inhibition on the interneurons within the spinal cord to stop the reflex from causing the heightened persistent muscle tone in the limbs.


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