Childhood Neurological Disorders

5 questions for each disorder:

1. Frequency - How common is the disease?

2. Cause

3. Part of CNS affected

4. Functions affected

5. Treatments or cures

Incidence

Rate at which new cases occur during a specified period (# of new diagnoses)

Prevalance

How many people have the disease at a given time

Possible causes:

• Genetic/developmental

• Injury

• Infectious Disease

• Toxicity/environmental

• Unknown/combination

Structure of neuron

Cell body (soma) has multiple dendrites (fibrous projections) and one axon covered in myelin

Gray matter

Cells arranged in structures called nuclei (located at the soma)

White matter

Axons (white because of myelin sheath)

Function of dendrites

Receive signals from other neurons

Myelin function

Speeds up signal transduction down the axon (makes signals faster)

Axon function

Sends signals to the soma of the next neuron

Major Divisions of the CNS (Rostral → Caudal)

Cerebral Hemispheres (cortex)

Thalamus and basal ganglia (subcortical)

Brainstem (midbrain, pons, and medulla)

Cerebellum

Spinal Cord

Brain Functions

• Sensory

  • Balance, vision, hearing, etc.

• Motor

  • Muscle tone, coordination, etc.

• Cognitive and affect

  • IQ, language, memory, emotion

Types of Treatments

• Medication

• Surgery

• Support (OT/PT, in-home care)

3 main childhood disorders

1. Down Syndrome (DS)

2. Krabbe Disease

3. Seizure Disorder (epilepsy before)

History of DS

People with DS used to be institutionalized, but now much more accepted

Frequency of DS

Not that common, 1 in 800 births

Cause of DS

Trisomy 12 (extra copy of chromosome 21)
Genetic cause

Trisomy Mosaic

Some cells have normal chromosome number, some have trisomy which results in less severe symptoms

Majority (75%) of DS cases result in…

Spontaneous miscarriage

DS Detection

Genetic testing, especially in older moms (higher risk) although most DS are born to young women

Symptoms of DS

• Developmental: facial structure

• Cognitive: Low IQ (variable), intellectual disability if IQ is less than 70

  • High functioning vs. Low functioning

• Motor: Delayed ‘motor milestones’

DS affect on CNS

Smaller cerebral cortex and cerebellum

Subcortical structures not affected as much as cortical

DS-associated Medical Problems

• Heart surgery due to structural problems

• Strabismus, myopia, spontaneous nystagmus (vision)

• Short stature, obesity

• Tongue thrust impairs speech

• Seizure and autism spectrum disorders

• C-spine instability

• Early onset Alzheimer’s

• Behavioral/Stereotypes

Strabismus

2 eyes don’t work together, requiring ocular muscle surgery

Myopia

Nearsightedness

Spontaneous nystagmus

Abnormal eye movements without stimulus

DS C-Spine Instability

Atlanto-axial subluxation not common in DS; too much movement between skull and spine is dangerous to spinal cord

Why are people with DS at risk for early onset Alzheimer’s?

Gene on chromosome 21 has a key protein in AD (more of chromosome 21 = higher risk)

Life expectancy for DS

Shorter than average, but has been improving with conditions

Treatment for DS

No cure; often requires therapy, special ed., support groups for families, change in society’s attitude

Krabbe Disease (GCL)

Abnormal structure of white matter and presence of globoid cells in the brain (AKA globoid cell leukodystrophy)

Frequency of Krabbe Disease

Very rare (1 in 100,000 live births)

Cause of Krabbe Disease

Autosome recessive gene mutation (hereditary - autosomal recessive)

Myelin in Krabbe Disease

Mutatation affects galactocerebrosidase which forms myelin, leading to wrong structure of myelin

Areas affected by Krabbe Disease

• Since myelination is not able to finish at birth:

  • The brain and spinal cord are all affected

Functions affected by Krabbe Disease

• Affect: babies are unusually irritable

• Motor: loss of control, increase muscle tone (stiffness)

Symptoms of Krabbe Disease

• Irritability

• Stiffness and no motor control

• Seizures, blindness, deafness

• Death by 2 years old

Life Expectancy for Krabbe Disease

2 years old; very short

Treatment for Krabbe Disease

• Cord blood transplants (HSCT - stem cell) must be done early to replace the defective gene

  • NOT cure, but increases life expectancy and QoL

• Newborn screening

• Irreversible

Seizure Disorder

Recurrent, unprovoked seizures (one seizure cannot be classified as SD)

Frequency of Seizure Disorder

Much more common than other childhood NDs; a good portion are pharmaco-resistant/intractable

What is a seizure?

Spontaneous, simultaneous discharges of neurons that generate many action potentials in the brain

Symptoms of a seizure

Variable, and depends on part of brain affects (seizure focus in where it starts)

Cause of Seizure Disorder

• Many different causes:

  • Brain structure (developmental or mutations)

  • Head injury (scar tissue → electrical abnormality)

  • Tumors

  • Multiple sclerosis (due to scar tissue)

Critical Parameters for Seizures:

1. Where did it start?

2. Is it motor or nonmotor (absence)?

3. Is consciousness affected?

Focal Onset Seizures

• Aware vs. impaired

  • Aware maintains consciousness

• Abnormal electrical activity is limited to a specific part of the brain

  • Determines symptoms

Seizure Classification Flowchart

Focal Impaired

• Temporal lobe origin

  • Temporal - complicated movements

  • No loss of postural control (stay standing)

• Not fully conscious, no memory

• Often preceded by an aura

Generalized Onset

• The entire brain is involved, falls into motor or non-motor:

  • Motor: tonic-clonic (two phases of seizure)

• Lasts seconds to minutes

Tonic Phase

Increased muscle tone; rigidity

Clonic Phase

Back and forth movement of body (contracting opposite muscles)

Seizure Triggers

Often no trigger but some are due to lights, sounds, etc.

Dangers of Seizures

• Generalized motor are not dangerous, but falling/drowning/car accidents are concerns

• STATUS EPILEPTICUS

Status Epilepticus

Prolonged, repeated seizures with no recovery between (5-10 minutes without consciousness)

Requires immediate medical treatment (IV, life support)

Seizure First Aid

1. Move objects

2. Pay attention to TIME (status)

3. Don’t hold person down, nothing in their mouth

4. Call 911 if longer than 5 minutes

Post-Ictal Period

Period immediately after seizure, causing confusion or deep sleep

Non-Motor (Absence) Seizure

• Staring spells, no loss of postural tone

• Most common in children, often outgrown

EEG

Diagnostic tool to record brain waves and find the seizure focus

Useful for determining type of seizure

Treatments for Seizure Disorder

Goal is to prevent/control seizures and risk of SUDEP:

1. Drugs

2. Ketogenic Diet

3. VNS

4. Brain surgery

Drugs for Seizure Disorder

Anti-epileptic Drugs (AEDs), don’t always work though

Ketogenic Diet

Very controlled diet high in fat, changing metabolism (Atkins or low glycemic index diets)

VNS (Vagal Nerve Stimulation)

Implanted pacemaker-like device delivering stimulation to brain via Vagus nerve

Surgeries for Seizure Disorder

1. Remove focus (small site to entire hemisphere)

2. Cut corpus callosum to prevent spread from 1 hemisphere to the other

Seizure Precautions

• Driving, swimming, alcohol should be limited

• Helmets - protective reflex doesn’t work