Multiple Sclerosis





2.5 million people live with MS


 

Multiple sclerosis (MS) is an immune-mediated inflammatory disease that attacks myelinated axons in the central nervous system, destroying the myelin and the axon in variable degrees and producing significant physical disability within 20- 25 years in more than 30% of patients. In most cases, the disease follows a relapsingremitting pattern (approximately 85% of cases), with short-term episodes of neurologic deficits that resolve completely or almost completely. A minority of patients experience steadily progressive neurologic deterioration.

The cause of MS is not known, but it likely involves a combination of genetic susceptibility and a presumed nongenetic trigger (e.g. viral infection, low vitamin D levels) that together result in a self-sustaining autoimmune disorder that leads to recurrent immune attacks on the CNS. Geographic variation in the incidence of MS supports the probability that environmental factors are involved in the etiology. The incidence of the disease is lower in the equatorial regions of the world than in the southernmost and northernmost regions.

A controversial hypothesis proposes a vascular rather than an immunologic cause for some cases of MS. The CCSVI hypothesis posits that stenosis of the main extracranial venous outflow pathways results in compromised drainage and a high rate of cerebral venous reflux and iron deposition in the brain parenchyma.

Given the paucity of supporting evidence, most MS experts question the CCSVI hypothesis. Worldwide, approximately 2.5 million people are affected by MS. As is true of autoimmune diseases in general, MS is more common in women. The female-to-male ratio of MS incidence is 3 to 1. MS is usually diagnosed in persons aged 20-50 years; however, it can occur in persons of any age. An estimated 8,000-10,000 children under the age of 18 also live with MS. The average age at diagnosis is 29 years in women and 31 years in men.

Diagnosis

MS is diagnosed on the basis of clinical findings and supporting evidence from ancillary tests.

Tests include the following: l Magnetic resonance imaging(MRI) of the brain and spine: The imaging procedure of choice for confirming MS and monitoring disease progression in the CNS l Evoked potentials: Used to identify subclinical lesions; results are not specific for MS l Lumbar puncture and cerebrospinal fluid examination (CSF): May be useful if MRI is unavailable or MRI findings are nondiagnostic; CSF is evaluated for oligoclonal bands and intrathecal immunoglobulin G (IgG) production Traditionally, MS could not be diagnosed after only a single symptomatic episode, as diagnosis required the occurrence of repeat clinical attacks suggesting the appearance of lesions separated in time and space; however, recent guidelines allow diagnosis of MS even with a first clinical episode as long as ancillary tests support separation of lesions in time or space.

Signs and symptoms

Attacks or exacerbations of multiple sclerosis (MS) are characterized by symptoms that reflect central nervous system (CNS) involvement. The sine qua non of MS is that symptomatic episodes are “separated in time and space” – that is, episodes occur months or years apart and affect different anatomic locations. In addition, the duration of the attack should be longer than 24 hours.

Additionally, it is important to recognize that the progression of physical and cognitive disability in MS may occur in the absence of clinical exacerbations.

Classic MS symptoms are as follows: l Sensory loss (ie, paresthesias) - Usually an early complaint l Spinal cord symptoms (motor) - Muscle cramping; weakness & spasticity l Spinal cord symptoms (autonomic) - Bladder, bowel, and sexual dysfunction l Cerebellar symptoms - Charcot triad of dysarthria, ataxia, and tremor. l Optic neuritis (ON) characterized by loss of vision (or loss of color vision) in the affected eye and pain on movement of the eye; can be the first demyelinating event in approximately 20% of patients. ON develops in approximately 40% of MS patients during the course of their disease. l Heat intolerance, may result in blurring of vision (Uhthoff sign), usually in an eye previously affected by ON l fatigue (which occurs in 70% of cases) and dizziness; fatigue must be differentiated from depression (which may, however, coexist), lack of sleep, and exertional exhaustion due to disability l Pain – Occurs in 30-50% of patients at some point in their illness l Subjective cognitive difficulties – With regard to attention span, concentration, memory, and judgment l Depression – A common symptom l Euphoria – Less common than depression

Management

Treatment and management of multiple sclerosis should be targeted toward relieving symptoms of the disease, treating acute exacerbations, shortening the duration of an acute relapse, reducing frequency of relapses, and preventing disease progression.

Drugs approved for use in MS that reduce the frequency of exacerbations or slow disability progression are referred to as disease-modifying drugs (DMDs). The DMDs currently approved for use by the US Food and Drug Administration (FDA) include the following: l Interferon beta-1a l Interferon beta-1b l Glatiramer acetate l Natalizumab has a black-box warning for progressive multifocal leukoencephalopathy (PML). Because of the risk of PML, natalizumab is available only through a special restricted distribution prescribing. l Fingolimod l Teriflunomide l Dimethyl fumarate Treatment of acute relapses is as follows: l Methylprednisolone can hasten recovery from an acute exacerbation of MS l Plasma exchange (plasmapheresis) can be used short term for severe attacks if steroids are contraindicated or ineffective The following agents are used for treatment of aggressive MS: l High-dose cyclophosphamide has been used for induction therapy l Mitoxantrone is approved for reducing neurologic disability and/or the frequency of clinical relapses in patients with SPMS, PRMS, or worsening RRMS

Prognosis

If left untreated, more than 30% of patients with MS will develop significant physical disability within 20-25 years after onset. Several of the disease-modifying agents used in MS have slowed disability progression within the duration of research trials.

Male patients with primary progressive MS have the worst prognosis, with less favorable response to treatment and rapidly accumulating disability. The higher incidence of spinal cord lesions in primary progressive MS is also a factor in the rapid development of disability. Life expectancy is shortened only slightly in persons with MS, and the survival rate is linked to disability. Death usually results from secondary complications (50-66%), such as pulmonary or renal causes, but can also be due to primary complications, suicide, and causes unrelated to MS.

The Author

Dr Suzan Noori is a consultant neurologist at Rashid Hospital Dubai. She is a member of the Royal College of Physicians in the UK and a collegiate member of the Royal College of Physicians in London. She is a Multiple Sclerosis certified specialist (USA) and she earned a postgraduate certificate in Multiple Sclerosis practice from Leeds Metropolitan University in UK. She earned an MBBS and MD from the University of Khartoum. She is licensed by the Dubai Health Authority , MOH and the General Medical Council in Sudan. Her special interests include Multiple Sclerosis, therapeutic use of botulinum toxin injections for spasticity and dystonia, Intrathecal (IT) Baclofen pump therapy refilling and programming for treatment of spasticity.

 Date of upload: 20th Nov 2013

 

                                  
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