Nervous System Pathology
Diseases of the CNS
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Recall CNS includes the brain and spinal cord
Examples of diseases that affect the CNS include:
(1) Infections (meningitis, encephalitis, polio)
(2) Degenerative diseases (Huntington’s, Alzheimer’s,
Parkinson’s, ALS, MS)
 (3) Epilepsy
 (4) Cerebral palsy
 (5) Genetic (Spina bifida, Tay Sachs)
Meningitis
 Meningitis is the inflammation of the meninges
 Recall the meninges consists of three protective layers that
surround the brain and spinal cord (dura mater, arachnoid, pia
mater)
 Meningitis can be caused by viral, bacterial, or fungal infections
 Swelling of the meningeal tissue often causes the typical
symptoms: headache, fever, stiff neck, confusion, vomiting
 Bacterial infections are especially serious and can lead to death in
the matter of a few days without treatment
Meningitis
Encephalitis
 Encephalitis is inflammation of the brain due most often to
viral infections
 Examples of viruses that can cause encephalitis include:
mosquito-borne like West Nile, Powassan virus (tick-borne),
 Symptoms can include flu-like symptoms, such as a fever or
severe headache. It can also cause confused thinking,
seizures, or problems with senses or movement
 Many cases of encephalitis present with mild flu-like to no
symptoms
Polio
 Also known as poliomyelitis, an
infectious disease caused by the
polio virus
 Highly infectious disease that can
damage the brain or spinal cord and
paralyze a person within hours
 Before introduction of the polio
vaccine, tens of thousands of
children developed paralytic polio
 4 part series of shots now to prevent
polio virus
FDR hid his disease so well many
never knew he had polio until after
his presidency. Only 3 photos of him
in a wheelchair are known to exist.
Huntington’s Disease
 An autosomal dominant disease
(inherited) that causes the
progressive breakdown of nerve
cells in the brain. Huntington's
disease has a broad impact on a
person's functional abilities and
usually results in movement,
thinking (cognitive) and
psychiatric disorders. Most
people with Huntington's disease
develop signs and symptoms in
their 30s or 40s, but the onset of
disease may be earlier or later in
life.
Eventually,
a
person
with
Huntington's disease requires
help with all activities of daily
living and care. Late in the
disease, he or she will likely be
confined to a bed and unable to
speak. However, he or she is
generally able to understand
language and has an awareness of
family and friends.
Huntington’s Disease
Alzheimer’s Disease
 Alzheimer's is the most
common form of dementia, a
general term for memory loss
and other intellectual abilities
serious enough to interfere
with daily life. Alzheimer's
disease accounts for 60 to 80
percent of dementia cases.
Alzheimer's is a progressive
disease, where dementia
symptoms gradually worsen
over a number of years.
Plaques, abnormal clusters of protein
fragments, build up between nerve cells.
Dead and dying nerve cells contain tangles,
which are made up of twisted strands of
another protein.
Alzheimer’s Disease
 Alzheimer's disease disrupts
both the way electrical
charges travel within cells
and the activity of
neurotransmitters.
Alzheimer's disease leads to
nerve cell death and tissue
loss throughout the brain.
Over time, the brain shrinks
dramatically, affecting nearly
all its functions. Shrinkage is
especially severe in the
hippocampus.
Parkinson’s Disease
 Parkinson's disease is caused by the
progressive
impairment
or
deterioration of neurons (nerve cells)
in an area of the brain known as the
substantia nigra. When functioning
normally, these neurons produce a
vital brain chemical known as
dopamine. Dopamine serves as a
chemical
messenger
allowing
communication
between
the
substantia nigra and another area of
the brain called the corpus striatum.
This communication coordinates
smooth
and
balanced
muscle
movement. A lack of dopamine
results in abnormal nerve functioning,
causing a loss in the ability to control
body movements.
ALS (Lou Gehrig's Disease)
 Amyotrophic lateral sclerosis is
the progressive degeneration of
motor neurons that eventually
leads to their death. When the
motor neurons die, the ability of
the brain to initiate and control
muscle movement is lost. With
voluntary
muscle
action
progressively affected, patients
in the later stages of the disease
may become totally paralyzed.
ALS (Lou Gehrig's Disease)
 As motor neurons degenerate,
they can no longer send
impulses to the muscle fibers
that normally result in muscle
movement. When muscles no
longer receive the messages
from the motor neurons that
they require to function, the
muscles begin to atrophy
(become smaller). Limbs begin
to look "thinner" as muscle
tissue atrophies.
Multiple Sclerosis (MS)
 MS is an autoimmune disease
that destroys the myelin
sheaths in the nerves of the
spinal cord and brain, as well as
the optic nerves. Sclerosis
means scarring, and people
with MS develop multiple areas
of scar tissue in response to the
nerve damage. Depending on
where the damage occurs,
symptoms
may
include
problems with muscle control,
balance, vision, or speech.
Epilepsy
 Epilepsy stems from an electrical glitch or malfunction, usually
in one region of the brain. During an epileptic seizure,
disturbances in the brain's orderly flow of electrical signals are
interrupted by abnormal electrical discharges. The type of
epileptic seizure depends on the area affected and the pattern
in which it spreads.
Epilepsy
 Scientists have identified
specific damage to the
neuron dendrite areas of
the cell. The observed
dendrite damage accounts
for the occurrence of
cognitive impairment seen
in those with seizure
disorders.
Cerebral Palsy
 Cerebral palsy is a group of
problems that affect body
movement and posture. It is
related to a brain injury or to
problems with brain
development. It is one of the
most common causes of
lasting disability in children.
 It can be caused by:
 Problems from being born too early
(premature birth).
 Not getting enough blood, oxygen, or
other nutrients before or during birth.
 A serious head injury.
 A serious infection that can affect the
brain, such as meningitis.
 Some problems passed from parent
to child (genetic conditions) that
affect brain development.
 In many cases, the exact cause of
cerebral palsy is not known
(idiopathic).
Cerebral Palsy
Spina Bifida
 Spina bifida is a type of birth
defect called a neural tube
defect. It occurs when the
bones of vertebrae don't form
properly around part of the
baby's spinal cord. Spina bifida
can be mild or severe. The mild
form is the most common. It
usually doesn't cause problems
or need treatment. You can't
see the defect, but some
people may have a dimple,
birthmark, or hairy patch on
their back.
 A rare and more severe form is
meningocele. In this form, fluid leaks
out of the spine and pushes against
the skin. You may see a bulge in the
skin.
Spina Bifida
 The most rare and severe form is myelomeningocele. Part of
the spinal nerves push out of the spinal canal, and the nerves
are often damaged. You may see a bulge in the skin. In some
babies, the skin is open and the nerves are exposed.
Tay Sachs Disease
 Children
with
Tay-Sachs
disease lack a vital enzyme,
hexosaminidase A (Hex-A).
Hex-A is needed for the body
to break down a fatty waste
substance found in brain
cells. Without Hex-A, this
substance
accumulates
abnormally
and
causes
progressive damage until the
nervous system can no
longer sustain life.
Tay Sachs Disease
 A baby with Tay-Sachs disease appears healthy at birth, and seems to be
developing normally for a few months. Symptoms generally appear by six
months of age. While symptoms vary from one child to the next, there is
always a slowing down of development. Gradually, Tay-Sachs children
lose motor skills and mental functions. Over time, the child becomes
blind, deaf, mentally retarded, paralyzed and non responsive to the
environment. Tay-Sachs children usually die by age five.
Diseases of the PNS
 Recall the PNS includes the nerves that stem from the brain and
spinal cord throughout the rest of the body
 Examples of diseases that affect the PNS include:
 (1) Carpal Tunnel Syndrome
 (2) Peripheral Neuropathy
Carpal Tunnel Syndrome
 Carpal tunnel syndrome occurs
when the median nerve, which
runs from the forearm into the
palm of the hand, becomes
pressed or squeezed at the
wrist. The median nerve
controls sensations to the palm
side of the thumb and fingers
(although not the little finger),
as well as impulses to some
small muscles in the hand that
allow the fingers and thumb to
move.
Peripheral Neuropathy
 The term peripheral neuropathy
encompasses a wide range of
disorders in which the nerves
outside of the brain and spinal
cord—peripheral
nerves—have
been
damaged.
Peripheral
neuropathy is a widespread
disorder, and there are many
underlying causes. Some of these
causes are common, such as
diabetes, and others are extremely
rare, such as leprosy.
Peripheral Neuropathy
 Typical symptoms of neuropathy are related to the type of
affected nerve. If a sensory nerve is damaged, common
symptoms include numbness, tingling in the area, a prickling
sensation, or pain. Pain associated with neuropathy can be
quite intense and may be described as cutting, stabbing,
crushing, or burning. In some cases, a nonpainful stimulus may
be perceived as excruciating or pain may be felt even in the
absence of a stimulus. Damage to a motor nerve is usually
indicated by weakness in the affected area.
Treatment for CNS Disorders
 Degenerative diseases and disorders of the central nervous
system (CNS) afflict tens of millions of people worldwide, and
often arise due to the failure of CNS tissue due to the loss of
functional cells. For many of these conditions, there are no
curative treatment options today and effective long-term
therapies remain limited.
 Stem Cell Research
 Deep Brain Stimulation (DBS)
Stem Cell Research
 Most of the advances in stem cell research have been directed
at treating degenerative diseases. While many treatments aim
to limit the damage of these diseases, in some cases scientists
believe that damage can be reversed by replacing lost cells
with new ones derived from cells that can mature into nerve
cells, called neural stem cells.
 Highly controversial; Embryonic stem cells must be used rather
than Adult Stem Cells
 Using embryonic stem cells kills the developing embryo
Stem Cell Research
Deep Brain Stimulation (DBS)
 Procedure
whereby
electrodes are placed in
the brain and deliver weak
electronic impulses to
stimulate neurons
 Patients return every 4
years
for
battery
replacement
 Has shown tremendous
promise in Parkinson’s,
individuals with major
depression, and PTSD
Early Diagnosis is Key
 Early Diagnosis - A new blood test for Alzheimer’s appears to detect
the disease as many as 10 years before clinical diagnosis is possible -far sooner than other tests in development. So far diagnosis has been
correct in 100% of the cases. A single protein in the brain involved in
insulin signaling, called IRS-1, that appears to be defective in
Alzheimer’s patients. They found that patients with Alzheimer’s had
higher amounts of the inactive form of the protein and lower
amounts of the active form than healthy individuals. The diabetics had
intermediate levels.
 These levels were so consistent that the team could predict whether a
blood sample came from an Alzheimer’s patient, healthy individual, or
a diabetic -- with no errors. This was true even for samples from
Alzheimer’s patients taken 10 years before they were diagnosed.