Definition and Causes:
DEFINITION:
- Multiple sclerosis (MS) is a disease that affects the brain and
spinal cord which is referred to as the central nervous system
(CNS)
- Inflammation caused by the immune system leads to injury of the
insulation (known as the myelin sheath) surrounding nerve cells
(neurons) within the CNS
- This injury disrupts the normal function and signals that is
sent from the brain and spinal cord to the rest of the body
CAUSES:
MS
is an autoimmune disease, i.e. the body's own immune cells, which
are normally used to defend us against invading organisms, such as
bacteria and viruses, somehow being to attack normal body tissue.
In this case the attack is against the insulation (or myelin)
surrounding the neuron (nerve cells) within the brain and spinal
cord.
The exact reason why the immune cells behave in this fashion is
unknown, but there have been speculation about:
- Environmental factors, it has been speculated
that exposure to certain drugs, toxins, viruses or chemicals in the
environment might trigger the immune system to malfunction, such
that it begins attacking the myelin within the CNS
- Genetic Factors, i.e some people may have
genes that might have the tendency to allow the development of
immune malfunction if they are exposed to certain toxins, viruses
etc.
- The amount of MS cases in the population depends on the
geographic location. MS is more prevalent in temperate countries as
compared to tropical countries and developing MS is related to
where a person lives during their first ~15 years of life, i.e.
individuals who grew up in tropical regions before moving to a
temperate country have a lower risk of developing MS, than someone
who grew up in a temperate country then moved to the tropics. This
observation as led to the notion that environmental factors play an
important role in causing of MS
Back to TopSymptoms:
There are different types of MS which varies in severity and
presentation.
Many patients will develop relapsing remitting symptoms, with
attacks interspersed with periods of normal functioning. There are
4 main types:
- Primary progressive MS (PPMS)
- Gradual progression with no remissions
- Progressive relapsing MS (PRMS)
- Steady cumulative progression of clinical neurologic damage
with some relapses and remissions
- Relapsing remitting MS (RRMS) (most common
initial presentation)
- Periods of relapse (often new neurological symptoms), followed
by periods of remission
- Secondary progressive MS (SPMS)
- Steady progression of neurologic symptoms and progressive
worsening
MS
Symptoms are varied and depends on the area of the central nervous
system CNS that is affected. Symptoms may include:
Vision problems:
- Optic neuritis (inflammation of the optic nerve of the eye) can
occur with or without MS
- The condition may affect one or both eyes
- Visual loss is variable and may be partial or complete
- Pain may occur and made worse by eye movements
Sensory disturbance:
- Can occur in any part of the body and patients may have a sense
of numbness, tingling, pins-and-needles, coldness, and decreased
sensitivity to touch
Reduced strength and co-ordination:
- Weakness and incoordination can affect any part of the body and
may result in weakness of face, arm leg, difficulty
speaking/drooling. There may be trouble coordinating movements such
that writing, eating, dressing and walking
Bowel/Bladder:
- Frequent and urgent need to urinate
- Patients may need to be checked for urinary tract
infections
- Constipation and loss of bowel control may occur
Sexual dysfunction:
- Men experience varying degrees of erectile dysfunction
- Women may experience a loss in sensation and pain during
intercourse
Weakness with exposure to heat:
- Exposure to hot conditions (sun, sauna, hot-tubs etc) increases
body temperature and may cause transient worsening of symptoms
Fatigue:
- Fatigue is a common complaint in MS
Depression:
- Many patients (>50%) may have some degree of depression
Cognitive dysfunction:
- Mental impairment can occur in MS, and as the disease
progresses may affect ~34-65% of patients
Epilepsy:
- 2 to 3% of patients may develop epilepsy
Back to TopInvestigations and Treatment:
Multiple sclerosis has no definitive diagnostic test. Diagnosis
depends on clinical presentation as well as the results of
investigative tests and ruling out other causes of myelin damage in
the central nervous system.
INVESTIGATION:
History
- Patients will be asked to describe the history of their
symptoms; when they first started, if the have ever gone into
remission, how often, and to describe any relapses
Blood work
- Patient's blood is examined for indicators of the presence of
other disease that may have similar symptoms.
Magnetic Resonance Imaging (MRI)
- A device used to take pictures of the internal organs,
including brain and spinal cord. This machine does not use x-rays.
Instead MRI uses magnetic fields over the body. The device looks
like a long cylindrical tube. Patients will lie on a table that
slides into the hollow tube. Computer analysis of magnetic fields
within the machine can generate images of the internal structures
of the body's organs, including the brain. In an MS patient a MRI
of the brain or spinal cord will show the normal structures, plus
any area of injury caused by inflammation will be commonly detected
as white spots called plaques. Patients must lie still inside a MRI
machine for several minutes. In some circumstances a dye might be
injected into the veins (enhanced MRI) just before the scan to help
improve detection of abnormalities. Patients who complain of
claustrophobia (fear of small space) may be given a mild sedative
to help relax prior to MRI scanning
Lumbar Puncture/Spinal tap for cerebrospinal fluid (CSF)
analysis
- A small amount of fluid called cerebrospinal fluid (CSF) is
removed from the patient's spine in the low back (lumbar) area and
sent for analysis. During the procedure the physician will clean
and drape the lumbar area. A local anesthetic is administered over
the skin where the needle is to be placed. Since the spinal cord
does not extend down into the lower lumbar region there is little
or no chance of causing injury to the spinal cord. The CSF is
extracted and sent for checking for special proteins that might be
present in MS. The test is not specific for MS, but with the right
clinical presentation and complementary MRI findings this may help
with the diagnosis of MS
Evoked potentials
- This procedure is used to measure how well the nerve cells are
conducting electrical signals within the brain and spinal cord.
Electrodes (small wires) are placed on the skin at various
locations on the arm or leg, spine and head, and time taken for
small electrical signals to reach the brain recorded. This can also
be done using the vision (visual evoked
potentials), hearing (auditory evoked
potentials) and sensory nerves on the body
(somatosensory evoked potentials). Observed delays
in signal communication allow doctors to figure out where the
damaged neurons in the body are located
TREATMENT:
Multiple sclerosis has no cure, however newer agents may help
reduced the inflammation and "slow down" the injury within the CNS;
treatment therefore involves modifying the path of the disease and
direct treatment of symptoms to minimize their effects on patients
and improve quality of life.
Disease Modifying therapy - helps to reduce inflammation
within the CNS
May be used in relapsing
remitting MS and secondary progressive MS
- Steroids - given intravenously or orally
- Helps to reduce the inflammation in the brain and spinal cord
that's associated with MS
- Usually given for exacerbations (flare-ups) over several
days
- Beta interferons (rebif, avonex)
- Used to slow the progression of MS symptoms. Used to suppress
the immune cells that are causing injury within the brain and
spinal cord. May cause stress on the liver and so blood tests will
be required to monitor liver function
- Glatiramer acetate (copaxone)
- This drug is injected under the skin once a day. It is believed
that it blocks the immune system from attacking the myelin sheaths.
Side effects include flushing and shortness of breath (transient
and occurs soon after soon after injection is administered)
- Fingolimod (gilenya)
- May help decrease certain type of immune cells within the CNS.
May require intermittent monitoring of liver and heart
function.
- Natalizumab (tysabri)
- Interferes with the movement of immune cells from the
bloodstream to the brain and spinal cord, and helps prevent
degradation of the myelin sheaths. This drug is usually prescribed
as a last resort as there is a small but potential risk of
developing a rare and extremely serious condition called
Progressive Multifocal Leukoencephalopathy (PML) which has a high
rate of death
- Mitoxantrone (novantrone)
- Suppresses the immune system, lowering the likelihood of attack
on myelin sheaths. May slow the course of secondary progressive MS.
Significant side effects requires use with caution. May be
associated with development of leukemia and can also be harmful to
the heart. As such, it is usually reserved for those refractory
(resistant) to other forms of treatment
- Other agents include
- Cyclophosphamide
- Methotrexate
- Azathioprine
- Cladribine
- Intravenous immunoglobulin (IVIG)
- May reduce the clinical attack rate in Relapsing Remitting MS;
Some data suggestive of benefit but not conclusive.
- Other Therapies under investigation
- Chronic Cerebrospinal Venous Insufficiency (CCSVI): A recent
hypothesis suggesting that impaired venous drainage from brain and
spinal cord leads to injury within the central nervous system that
is related to MS
- Please see CCSVI.ca for position statements from the Canadian
Medical Association (CMA) and the Canadian Institutes of Health
Research (CIHR)
Symptomatic Treatment
Symptomatic treatment is necessary and complex due to the
widespread effect of the disease on the function of the central
nervous system. Some symptoms requiring treatment are as
follows:
Spasticity
- To prevent stiffness and muscle spasms, patients may be
prescribed muscle relaxants such as baclofen and tizanidine. Side
effects include include weakness and drowsiness
Fatigue
- Patients may be prescribed drugs such as amantadine to help
reduce their fatigue. Antidepressants may also be recommended for
fatigue associated with depression
Pain
- Patients complaining of acute or chronic pain may be prescribed
usual analgesics (acetaminophen, ibuprofen). Depending on the type
and location of pain other drugs which might be consider includes:
Neuronotin, lyrica, tramadol, cymbalta and tegretol among
others
Bladder dysfunction
- Patients suffering with bladder spams may require drugs to help
control them (e.g. Ditropan). Patients who have lost the ability to
control their bladder may have to use intermittent
self-catheterization which involves sliding a thin tube through the
urethra (channel from balder to exterior of penis/vagina) into the
bladder, allowing urine to drain freely
Bowel dysfunction
- Drugs may be prescribed to help with control. Patients may be
recommended to use fiber and stool softeners to treat
constipation
Sexual dysfunction
- Males with erectile dysfunction may be offered treatment with
agents such as tadalafil (cialis), sildenafil (viagra) and
vardenafil (levitra). Caution is advised in the elderly and those
with cardiac disease. Water-based lubricants may be suggested to
women with insufficient natural vaginal lubrication
Back to TopRisk Factors and Prevention:
No definite cause has yet been discovered for multiple
sclerosis, however, the following have been observed.
- Typical age of onset is between 20-40 years old; average age at
onset is 32 years old
- Females are twice as likely as Males to develop MS
- Family history may have a weak genetic link (<5%)
- Infection: Epstein-Barr virus has been suggested
- Caucasians are more likely than other races to develop MS
- Location - temperate climate
Back to TopOutcome:
There is no known cure for MS. Treatments are geared at slowing
the progression of attacks and reducing the effects of symptoms on
the body.
- If untreated, more than 30% of patients with multiple sclerosis
will develop significant physical disability within 20-25 years
from onset
- 70% of patients lead active, productive lives with prolonged
remissions
- 30% relapse in 1 year, 20% in 5-9 years, and 10% in 10-30
years
- Patients with MS are thought to have a slightly lower average
life expectancy; 5-7 years shorter than that of the general
population
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