Encyclopedia of Health and Medicine

multiple sclerosis 263
CEREBROSPINAL FLUID circulates between the
arachnoid mater and the pia mater, in an envelope-like
pocket called the subarachnoid space.
DURA MATER GRAFTS AND CJD
For several decades neurosurgeons have used
grafts of dura mater acquired from cadaver
donors to replace dura mater removed during
neurosurgery or in circumstances of extensive
injury to the BRAIN. In the late 1990s researchers
traced several cases of CREUTZFELDT-JAKOB DISEASE
(CJD) to the grafts, which had been harvested
from individuals who turned out to have CJD. US
Food and Drug Administration (FDA) regulations
now establish strict criteria for the harvesting and
processing of dura mater grafts to reduce the risk
of transmitting infectious conditions such as CJD.
For further discussion of the meninges within
the context of the structures and functions of the
NERVOUS SYSTEM, please see the overview section
“The Nervous System.”
See also MENIGITIS.
multiple sclerosis A chronic, progressive
demyelinating disorder that affects the CENTRAL
NERVOUS SYSTEM (BRAIN and SPINAL CORD) and the
CRANIAL NERVES, notably the optic nerves. Though
the cause of multiple sclerosis remains unknown,
most researchers believe the condition is an
autoimmune disorders in which the body’s IMMUNE
RESPONSE attacks myelin, the fatty substance that
coats nerves. The areas under attack become
inflamed and separate from the nerves, and as
they heal scars form. Over time the SCAR tissue
damages the nerves and disrupts the passage of
electrical impulses. The progression of demyelination
is generally slow, occurring over several
decades. There is wide variation in the severity of
multiple sclerosis among individuals. Some people
experience few symptoms and negligible interference
with their regular activities and other people
lose control of muscles and mobility.
Symptoms and Diagnostic Path
One of the earliest signs of multiple sclerosis is
RETROBULBAR NEURITIS, an INFLAMMATION of the OPTIC
NERVE (second cranial NERVE) that impairs vision.
Indications of retrobulbar neuritis include DIPLOPIA
(double vision), blurred vision, impaired color
vision and scotomas (blind spots in the field of
vision). Other symptoms are neurologic and
include
• weakness and lack of coordination in the arm
or leg on one side of the body
• gait disturbances such as stumbling
• transient PARESTHESIA (tingling or numbness that
comes and goes without apparent cause) on
one side of the body
• intermittent loss of BLADDER control (URINARY
INCONTINENCE)
• emotional lability
• VERTIGO and dizziness
• fatigue
• SEXUAL DYSFUNCTION (notably ERECTILE DYSFUNC-
TION in men)
Because symptoms are typically transient they
often occur over a number of years before a person
seeks medical attention for them. The diagnosis is
primarily one of exclusion so the diagnostic path
includes a general medical examination, BLOOD
tests, NEUROLOGIC EXAMINATION, LUMBAR PUNCTURE,
and imaging procedures such as MAGNETIC RESO-
NANCE IMAGING (MRI) of the brain to rule out other
potential causes, such as BRAIN TUMOR, of symptoms.
Imaging procedures, especially MRI, also may show
the lesions (scarring) that characterize multiple
sclerosis. However, there is no conclusive diagnostic
test for multiple sclerosis and a person may seek
medical care for a number of years before doctors
feel confident making the diagnosis.
Heat often worsens the symptoms of
multiple sclerosis. For this reason, doctors
advise against hot tubs, saunas,
exposure to hot weather, and hot showers
or baths.
Treatment Options and Outlook
For most people the course of multiple sclerosis is
one of alternating relapse and REMISSION, without
predictability for the frequency or duration of
either. Treatment depends on the severity and frequency
of symptoms. People who have mild