Diagnosis of multiple sclerosis (MS) involves
taking a family history and a history of symptoms, and performing a
physical examination (including neurological examination) and various
tests (including blood tests and imaging tests).
Blood tests: Many
blood tests may be used to determine if MS is present. They include a
complete blood count (CBC), liver function tests, testing for Lyme
disease, a creatine kinase test, and a DNA analysis (to determine if the
disorder is genetic) among others. In some cases, a cerebrospinal fluid
(CSF) analysis also is performed.
Cerebrospinal fluid analysis
involves performing a spinal tap or lumbar puncture. In this procedure,
about two tablespoons of cerebrospinal fluid is drawn into a needle
inserted between two lumbar vertebrae and then examined under a
microscope. In cases of MS, the doctor may see an elevation of protein
and white blood cells in the cerebrospinal fluid. This procedure is
usually performed in a hospital or clinic under local anesthesia,
although general anesthesia can be used.
Imaging tests: Imaging
tests, including computed tomography (CT scan), magnetic resonance
imaging (MRI scan), and positron emission tomography (PET scan), may be
used to detect damage (such as shrinkage) in the basal ganglia,
structural abnormalities, and stroke (neurological damage due to a lack
of oxygen to the brain).
Other imaging tests: An electromyogram
(EMG) and an electroencephalogram (EEG) also may be performed. These
tests are used to monitor electrical activity within the body and can
help detect nerve and muscle disorders. EMG involves placing electrodes
on the skin (surface EMG) or needles into the muscle (intramuscular EMG)
to record electrical activity of the muscle. In an EEG, electrodes are
attached to the scalp and connected to a machine that records electrical
impulses in the brain.
Muscle biopsy: A muscle biopsy may also be
performed to distinguish between nerve and muscle disorders. This
procedure, which is performed under local anesthesia, involves making a
small incision and removing a sample of muscle for microscopic
evaluation to determine if the muscle tissue is being damaged. Following
the procedure, patients may experience minor pain and bruising at the
biopsy site for about one week.
Evoked potential tests: Evoked
potentials are electrical signals generated by the nervous system in
response to stimuli. Evoked potential tests (including somatosensory
evoked potentials, visual evoked potentials, and brainstem auditory
evoked potentials) are performed to evaluate sensory, visual, and
auditory functions and detect slowed nerve impulse conduction caused by
demyelination. In these tests, nerves responsible for each type of
function are stimulated electronically and responses are recorded using
electrodes placed over the CNS (brain and spine) and peripheral nerves
(including the median nerve in the wrist and the peroneal nerve in the