Multiple sclerosis (MS) is one of the most common diseases of the central nervous system (CNS). Arou...
Multiple sclerosis (MS) is one of the most common diseases of the central nervous system (CNS). Around two million people have MS worldwide, but it is more common in some countries than others. Women are also more likely to develop MS than men, occurring 50% more frequently (in other words three women for every two men). MS is a disease of young adults and the average age of onset is 29-33 years, but the range of onset is extremely broad from approximately 10-59 years.
There does appear to be some genetic susceptibility to the disease and occurrence is likely to involve multiple genes.
MS occurs more often in temperate regions and, like other auto-immune diseases, less in the tropics. In the UK, for instance, MS is more common in the north of the country. There could be many reasons for this, including a correlation between infectious diseases and climate bands, and variations in genetic susceptibility for MS between different ethnic groups.
Clinical definitions
MS is a major disease and highlights how important critical illness cover for the disease is in today's society. The Association of British Insurers (ABI) definition is: A definite diagnosis by a consultant neurologist of multiple sclerosis which satisfies the following criteria:
l There must be current impairment of motor or sensory function, which must have persisted for a continuous period of at least six months.
l The diagnosis must be confirmed by diagnostic techniques current at the time of the claim.
If we look at the first part of the definition, this requires a definite diagnosis of MS. Unfortunately, the course of MS is unpredictable. Diagnosis is generally made by means of observation of the clinical course in conjunction with a neurological examination and laboratory tests.
In its initial manifestations, the diagnosis of MS can be difficult - early MS may present itself as a history of vague symptoms which may have subsided and many of the signs on further investigations could be attributed to a number of medical conditions such as, trigeminal neuralgia, chronic fatigue syndrome (ME), paraesthesia and so on. There are clinical definitions of definite, probable, and possible MS and these will determine whether the applicant's condition meets the criteria in the definition.
Definite multiple sclerosis
Definite multiple sclerosis consists of two attacks, each involving different parts of the central nervous system (CNS). These can last at least 24 hours and be separated by at least one month.
Definite multiple sclerosis may also be diagnosed with laboratory support. This means that one of the two episodes must involve a part of the CNS distinct from that demonstrated on clinical examination or by paraclinical evidence, in other words electrophysiological, neuro-imaging or cerebrospinal fluid (CSF) examination. The course of MS is extremely difficult to predict and it may be many years before another attack occurs. However, in some cases the progression of the disease can be much more rapid and can lead to a significant degree of disability which affects lifestyle.
Probable multiple sclerosis
Probable multiple sclerosis shows a variety of syndromes within its definition. It can be two attacks that involves evidence of only one lesion, or one attack with evidence of two lesions, or one attack with evidence of another lesion. Laboratory supported probable multiple sclerosis requires the presence of an abnormal CSF examination.
Possible multiple sclerosis
Possible multiple sclerosis is a common clinical problem in which there is only one lesion, the clinical evidence is scanty or indefinite, but the symptom is itself strongly suggestive of the disease, for example, trigeminal neuralgia in a person less than 40-years old.
The symptoms of probable and possible MS, although in themselves are worrying, are not disabling and would not usually result in the individual being unable to live a normal life.
Furthermore, there may never be any further symptoms suggesting that they may never have been MS-related. The CI definition requires impairment of motor and sensory function to have lasted six months. Many minor ailments will normally have subsided in this time period. As there remains some uncertainty over the diagnosis, claims arising due to probable or possible MS are outside the scope of the MS CI definition. It may be that a further episode does occur and a definite diagnosis is made, thus bringing a claim within the scope of the CI definition.
Diagnostic tests
If we take the last part of the CI definition of MS, we note that the diagnosis must be confirmed by diagnostic techniques current at the time of the claim. MS is essentially a clinical diagnosis and there are no tests which are specific for the condition and no single test is 100% conclusive. Therefore, several tests and procedures are needed to establish a diagnosis of MS and we will look briefly at the following techniques used.
Medical history
The physician will ask for a medical history which will include past records of signs and symptoms as well as the current status of health. The type of symptoms, their onset and pattern may suggest MS, but a full physical examination and medical tests will be needed to confirm the diagnosis.
Neurological examination
The neurologist will test for abnormalities in nerve pathways. Some of the more common neurological signs involve changes in eye movements, limb co-ordination, weakness, balance, sensation, speech, and reflexes. However, this examination cannot conclude what is causing the abnormality and so other possible causes of illness which produce similar symptoms to MS must be eliminated.
Testing of visual and auditory evoked
When demyelination (scarring) occurs, the conduction of messages along the nerves may be slowed. Evoked potentials measure the time taken for the brain to receive and interpret messages (nerve conduction velocity). This is done by placing small electrodes on the head which monitor brain waves in response to visual and auditory (hearing) stimuli. Normally, the brain's reaction to such stimuli is almost instantaneous, but if there is demyelination in the CNS, a delay may occur.
Magnetic resonance imaging (MRI)
The MRI scanner is a more recent diagnostic test and takes detailed pictures of the brain and spinal cord, showing any existing areas of sclerosis (lesions or plaques).
While this is the only test in which the lesions of MS can be seen, it cannot be regarded as conclusive, particularly as not all lesions may be picked up by the scanner and because many other conditions can produce identical abnormalities. The MRI clearly shows the size, quantity and distribution of lesions, and together with supporting evidence from medical history and neurological examination, is a very significant indicator toward confirming the diagnosis of MS.
Lumbar puncture
In this test, cerebrospinal fluid (the fluid which flows around the brain and spinal cord) is tested for the presence of antibodies. Antibodies can occur with MS, but they can also occur with other neurological conditions. The fluid is taken from the spinal cord by inserting a needle into the back and withdrawing a small amount of fluid. This test may indicate MS but is not conclusive.
It is impossible to predict accurately the course of MS for any individual, but the first five years give some indication of how the disease will continue. This is based upon the course of the disease over that period and the disease type (in other words, relapses, remitting or progression). The level of disability reached at end points such as five and 10 years is thought to be a reliable predictor of the future course of the disease.
As with other critical illness conditions, the industry has had to produce a product which is cost-effective and as a result, a definite diagnosis must be confirmed. While there are other conditions such as probable or possible MS which would be desirable to cover, the need to keep the price of cover affordable will continue to influence the product design.
Katie Bamber is individual protection life and disability underwriter at Scottish Equitable
