There are four main types of MS: benign, relapsing-remitting, secondary progressive and primary progressive. Most people with MS will suffer from the relapsing-remitting form of the disease to begin with. As the name suggests, this type of MS is characterized by periods of remission and relapse. The relapses are unpredictable and may affect people in different ways each time. The severity of relapses can vary greatly, as can the duration. a relapse can last from hours to months. In the early stages of MS, people are generally symptom-free in periods of remission. Some people with MS have a benign form of the disease. People with this type seem to undergo a complete recovery after a few mild attacks with no resulting permanent disability or illness. Very occasionally, some disability may develop at a later date. Secondary progressive MS is a phase of the disease that develops after relapsing-remitting MS. People with this form of the disease do not recover completely from any disability evident during a relapse and their condition worsens progressively. Some people with MS suffer from increasingly severe symptoms and progressive disability from the outset, never having distinct periods of relapse or remission. This type is known as primary progressive MS.
What tests confirm a diagnosis of MS?
MS is difficult to diagnose because the symptoms may be very vague and there are no specific conclusive tests. A diagnosis of MS is not usually made until a person has experienced two separate bouts of symptoms involving different areas of the central nervous system. Each of these bouts should have lasted for at least 24 hours and the two should have occurred more than a month apart. The doctor will need to perform various tests to confirm the diagnosis. The doctor will usually perform a neurological examination to assess coordination of limbs, balance and reflexes, and to look for any signs of weakness or changes in speech or eye movements. Any changes or problems may indicate abnormalities in the nerve pathways involved in movement or sensation.
Evoked potential tests may also be performed. These tests involve the use of small electrodes, which are attached to the head in order to monitor brain activity in response to sights or sounds. If there is nerve damage these responses may be delayed. A magnetic resonance imaging (MRI) scan can take detailed pictures of the brain and spinal cord and will usually show any plaques that are present. An MRI scan confirms the diagnosis in over 90% of cases. A lumbar puncture may also be performed. Lumbar punctures are usually done under local anesthetic and involve the insertion of a needle into the lower back to take fluid from the spinal cord. Characteristic abnormalities in protein patterns may be detected in the fluid if MS is present. Alternatively, a computer axial tomography (CAT) scan may be performed – this is similar to an MRI scan and is used to show a cross-section of the brain.