By Dr Ananya Mandal, MD
Multiple Sclerosis (MS) can be difficult to diagnose when a person has had just one “attack” of what appears to be MS symptoms. Other conditions share MS symptoms and a physician will need to rule those out first.
Usually, a diagnosis is made after a person has experienced several episodes of symptoms. If a doctor suspects a patient may be suffering from MS, a neurologist may carry out several tests to confirm the diagnosis.
Examples of the tests that are used to diagnose MS include:
The patient is assessed for adequate functioning of the nervous system. This includes tests of co-ordination, balance, reflexes, vision, speech and sensation. A neurologist checks for symptoms of parasthesia, which refers to numbness and tingling sensations such as “pins and needles” or “dead” limbs. In MS, speech may be interspersed by long pauses or slurred due to poor coordination of speech articulators such as the tongue and lips.
Magnetic Resonance Imaging (MRI)
An MRI scan is used to give a detailed image of the brain and spinal cord to reveal the presence of any damaged myelin, the protective coating that surrounds nerve fibres. The majority (90%) of individuals with MS have their condition confirmed using MRI. The procedure is painless and takes around half an hour to perform.
Also called a spinal tap, this procedure involves taking a sample of the fluid from the area surrounding a patient’s spinal cord. This cerebrospinal fluid (CSF) is tested for antibodies, the presence of which indicates that the immune system has been attacking the nervous system. A lumbar test is usually only performed if other tests for MS have not been able to confirm the diagnosis.
Evoked potentials test
For this test, electrodes are applied to the patient’s head to monitor the brain’s responses to visual and auditory stimulation and show whether nerve transmission is occurring normally.
Blood test are run to check for any alternative causes of symptoms.
Types of Multiple Sclerosis (MS)
Once an MS diagnosis is confirmed, the neurologist can identify which form of MS a patient has, although the patients may need to be monitored for some time before this can be decided.
Relapsing remitting MS may be diagnosed when two episodes of relapse are separated by more than 30 days or there has only been one relapse but there is MRI evidence of newly scarred or damaged myelin three months later.
Secondary progressive MS may be diagnosed if the patient has had relapses in the past or if there has been a steadily increasing disability for at least 6 months, with or without relapses.
Primary progressive MS may be diagnosed if there have been no previous symptoms of relapse but the patient has become increasingly disabled over a period of at least one year as well as an MRI scan showing damaged myelin and a CSF being positive for antibodies.
Reviewed by Sally Robertson, BSc