Neurological Disorders: Definition, Categories, Etiology and Prevalence

DEFINITION

The human central nervous system consists of the brain, the spinal cord, and all the associated nerves and sense organs. Neurological impairments result from damage or dysfunction of the brain/or spinal cord. It can occur before, during or after birth.

Potential causes include:

• Severe lack of oxygen before birth, especially in the first trimester.
• Damage suffered during the birthing process.
• Damage caused by diseases (especially those that attack the Central Nervous System).
• Injury to the spinal cord/brain injury.

Neurological disabilities include:

• Cerebral Palsy
• Spina Bifida
• Epilepsy
• Tourette Syndrome
• Traumatic Brain Injury
• Fetal Alcohol Spectrum Disorders

*We are focusing on Cerebral Palsy, Spina Bifida, Traumatic Brain Injury and Fetal Alcohol Spectrum Disorder.

Prevalence of Neurological Disorders:

• About 0.2 - 1.5% or 2 per 1000 school aged population.

CATEGORIES:

CEREBRAL PALSY (CP):

Definition: 

•  Cerebral Palsy is a condition characterized by damage to the brain before, during or after birth.
•   CP is classified mainly as a motor disorder; however there are co-occurring conditions that lead to multiple disorders.

Prevalence: 

•   CP is the most common condition affecting motor ability in children, with about 1.5 – 2 cases per 1000 live births. 
• About 5000 Canadians have CP.

Etiology:

• More than two-thirds of cases are present at birth.
• 25% of cases have no definable cause.
• An extensive study found that the most likely associated factors were cognitive disability of the mother, premature birth/low birth weight and delay of 5 minutes before baby’s first cry.
• Injury to the brain.
• Disease such as meningitis.

Classification of Cerebral Palsy:

Spastic or Pyramidal CP (Hypertonia) – Individuals have suffered damage to the motor cortex or to the Pyramidal Tract of the brain, (affects approx. 50% of children with CP)

• Pyramidal CP results in problems with controlled movements.
• Spasticity refers to slow, poorly co-ordinated controlled movements.

Extra Pyramidal CP- differs from spasticity CP in that the damage is outside the pyramidal tract. The condition includes:

• Tremor
• Rigidity
• Ataxia (15% of affected individuals)
• Athetiod (25% of affected individuals)

Where there is damage to both the Pyramidal and the Extra Pyramidal regions of the brain the child may show mixed effects, such as spasticity of the legs and rigidity of the arms. About 25% of cases are classified as mixed CP.

SPINA BIFIDA (SB):

Definition

Spina Bifida is a neural tube defect which occurs when 1 or more vertebrae in the spinal column does not close during prenatal development. This incomplete closing in the spinal column allows fluid or part of the spinal cord to transfer through the opening.

Prevalence:

• The prevalence of Spina Bifida varies widely from country to country, area to area and even within the city limits of a particular city. 
•  Spina Bifida occurs from 0.1 – 4.13 live births per 1000 worldwide. 
• In Canada, Newfoundland and Labrador have the highest rates.

Etiology:

• The actual cause of Spina Bifida is unknown. 
•   Etiologically it is believed that both heredity and environment are interweaving factors. 
•  If one baby has SB there is a 4-5% chance of siblings having it.

Classifications of Spina Bifida

Spina Bifida Occulata (40%) 

•  Mildest form and has few or no negative effects.

Spina Bifida Cystica (60%) divided into two groups:

• S.B. Menegocele 4%
• S.B. Myelomeningocele 96%

Spina Bifida Meningocele

• The membranes surrounding the spinal cord protrude from the plane of the spine and form a sac containing cerebrospinal fluid.

Spina Bifida Myelomeningocele

• The most severe type resulting in a protruding sac that contains parts of the spinal cord as well as cerebrospinal fluid. The higher the sac, the greater the damage.

TRAUMATIC BRAIN INJURY (TBI):

Definition

Traumatic Brain Injury (TBI) is defined as a sudden injury that damages the brain (permanently or temporarily) after birth.

Prevalence 

•  In the USA over 1 million children a year are identified with TBI. 
•   In Canada more than 300 children die, and more than 20,500 are hospitalized with serious injuries each year.
• Injuries are more likely to occur among poor children, boys and aboriginal children and youth.

Etiology

• Most common injuries that lead to brain damage include: car accidents, near-drowning, violence related, motor cycles/bicycles and sports related injuries.

Classifications of Traumatic Brain Injury

• TBI is not selective in its damage. 
•  It can cause diffused cerebral swelling due to increased blood volume, and several areas of the brain can therefore be affected.
•  Depending on the severity and location of the head trauma, TBI can result in the disturbance of behaviour or emotional functioning, physical and perceptual motor defects.  
•  Frontal lobe damage is the most common form of injury and ensures diminished cognitive capacity.

FETAL ALCOHOL SPECTRUM DISORDER(FASD):

Definition

 FASD is an entire spectrum of disorders that include diagnostic categories such as Neurobehavioral Disorders, Static Encephalopathy, and Fetal Alcohol Syndrome (FAS), which is caused by maternal consumption of alcohol during gestation.

Prevalence

•   Estimated to be 1.9 per 1000 live births with FASD.
• About 1 of every 750 infants is born with FAS.

Etiology

•  Fetal damage occurs because the body uses large quantities of oxygen to metabolize alcohol, oxygen that the developing fetus needs for cell growth. Also, the ethanol in the alcohol takes fluid from the developing brain causing the death of brain cells. 
•  The exact connection between the amount of alcohol consumption and reproductive risk is not clear. Infants of mothers who drink excessively are at greater risk.    It is suggested that as little as one ounce of alcohol a day can create a drop of six or seven points in IQ.

        

Classifications of FASD

Fetal Alcohol Syndrome

 

• Growth deficiencies that stunt prenatal and/or postnatal growth
• Permanent brain damage resulting in neurological abnormalities
• Facial anomalies including short eye opening and thin upper lip
• Maternal use of alcohol during pregnancy

Neurobehavioral Disorder 

•  Dysfunction of the central nervous system (mild functional impairment with no evidence of structural or neurological abnormalities) cause by maternal use of alcohol during pregnancy.

Static encephalopathy

• Unchanging significant abnormal condition of the structure or function of brain tissues as a result of prenatal alcohol exposure.

 Watch this video about FAS: 

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Please visit for more information:FASlink Fetal Alcohol Disorders Society