Multiple sclerosis (MS) is one of the most common diseases of the central nervous system. Today over 2,500,000 people around the world have MS.MS is the result of damage to myelin – a protective sheath surrounding nerve fibres of the central nervous system. When myelin is damaged, this interferes with messages between the brain and other parts of the bodySymptoms vary widely and include blurred vision, weak limbs, tingling sensations, unsteadiness and fatigue. For some people, MS is characterised by periods of relapse and remission while for others it has a progressive pattern. For everyone, it makes life unpredictable.
Research has been difficult to do on patients with MS for many reasons. One reason is the area is often inaccessible because MS occurs is the Brain and Cervical spinal cord. Antoher important reason is that every patient disease does not follow the same pattern of progression. This is why comparing patients can be so difficult. MS is also very unpredictable, which makes it hard to treat. Patients may not be showing symptoms but may have underlying disease process . There are four types of MS, (see chart)
In this form of MS there are unpredictable relapses (exacerbations, attacks) during which new symptoms appear or existing symptoms become more severe. This can last for varying periods (days or months) and there is partial or total remission (recovery). The disease may be inactive for months or years.
Frequency – approx 25%Benign MS
After one or two attacks with complete recovery, this form of MS does not worsen with time and there is no permanent disability. Benign MS can only be identified when there is minimal disability 10-15 years after onset and initially would have been categorised as relapsing-remitting MS. Benign MS tends to be associated with less severe symptoms at onset (e.g. sensory).
Frequency – approx 20%
Secondary Progressive MS
For some individuals who initially have relapsing-remitting MS, there is the development of progressive disability later in the course of the disease often with superimposed relapses.
Frequency – approx 40%
Primary Progressive MS
This form of MS is characterised by a lack of distinct attacks, but with slow onset and steadily worsening symptoms. There is an accumulation of deficits and disability which may level off at some point or continue over months and years.
Frequency – approx 15%
MRI imaging has come a long way in being able to detect small lesions in the brain and spinal cord. The most useful sequences in MRI scanning are Flair Sagitals and Axials. Lesions on T2 axial scans of the brain are hyperintense an hypointense on T1 weighted images.
and will return to isointensity over the next several months. However, chronic lesions that persist over several months likely represent irreversible and profound
tissue damage due to demyelination and axonal loss. Brain hypointense T1-weighted lesions have correlated better with disability than have lesions on T2-weighted images in some but not all studies.
more sensitive to disease activity than clinical relapses. Moreover, the appearance of Gd-enhancing lesions predicts future relapses but not long-term disability.Gdenhancing lesions, which may appear as homogeneous, heterogeneous, tumor-like, and ring enhanced, are more commonly seen in patients with relapsing-remitting MS (RRMS) than in patients with progressive forms of the disease.
The open-ring pattern is particularly characteristic
of MS lesions.
(Rohit Bakshi, MD, FAAN)
Cutting Edge MRI
There is no known definitive cure for multiple sclerosis. However, several types of therapy have proven to be helpful. Different therapies are used for patients experiencing acute attacks, for patients who have the relapsing-remitting subtype, for patients who have the progressive subtypes, for patients without a diagnosis of MS who have a demyelinating event, and for managing the various consequences of MS attacks. Treatment is aimed at returning function after an attack, preventing new attacks, and preventing disability.
Various disease-modifying treatments have been approved by the USA’s Food and Drug Administration (FDA) for multiple sclerosis.
These are medications derived from human cytokines which help regulate the immune system. Betaseron has been approved by the FDA for relapsing forms of secondary progressive MS.
Interferon beta-1a: (trade names Avonex and Rebif)
beta-1b: (trade name Betaseron [in Europe and Japan Betaferon]).
GLATIRAMER ACETATE: (trade name Copaxone)
A synthetic medication made of four amino acids that are found in myelin. This drug stimulates T cells in the body’s immune system to change from harmful, pro-inflammatory agents to beneficial, anti-inflammatory agents that work to reduce inflammation at lesion sites.
MITOXANTRONE: (trade name Novantrone)
This medication is effective, but is limited by cardiac toxicity. Novantrone has been approved by the FDA for secondary progressive, progressive-relapsing, and worsening relapsing-remitting MS.
NATALIZUMAB: (trade name Tysabri).
This medication is effective and safe alone but in combination with other immunotherapies can lead to PML.
Relapsing-remitting symptomatic attacks can be treated. Patients in the United States are typically given high doses of intravenous corticosteroids, such as methylprednisolone, to end the attack sooner and leave fewer lasting deficits. Patients’ self-reporting indicates that many find benefit from a number of other medicines.
Currently there are no approved treatments for primary progressive multiple sclerosis, though several medications are being studied and are described at Therapies for multiple sclerosis.