Thursday, April 29, 2010

Motor Neurone Disease (MND) is a progressive neurodegenerative disease that attacks the upper and lower motor neurones. This dsease basically causes loss of mobility in the limbs, and difficulties with speech, swallowing and breathing. This disease refers to a group of diseases that affect motor neurones. There are other diseases of the motor neuron that should not be confused with MND such as spinobulbar muscular atrophy, spinal muscular atrophy, Charcot-Marie-Tooth disease, and many others.
About 90% of cases of MND are "sporadic", meaning that the patient has no family history of ALS and the case appears to have occurred with no known cause. Genetic factors are suspected to be important in determining an individual's susceptibility to disease, and there is some weak evidence to suggest that onset can be "triggered" by as yet unknown environmental factor.
Approximately 10% of cases are "familial MND", defined either by a family history of MND or by testing positive for a known genetic mutation associated with the disease. The following genes are known to be linked to ALS: Cu/Zn superoxide dismutase SOD1, ALS2, NEFH (a small number of cases), senataxin (SETX) and vesicle associated protein B (VAPB).
Symptoms usually present themselves between the ages of 50-70, and include progressive weakness, muscle wasting, and muscle fasciculations, spasticity or stiffness in the arms and legs, and overactive tendon reflexes. Patients may present with symptoms as diverse as a dragging foot, unilateral muscle wasting in the hands, or slurred speech.
Neurological examination presents specific signs associated with upper and lower motor neurone degeneration. Signs of upper motor neurone damage include spasticity, brisk reflexes and the Babinski sign. Signs of lower motor neurone damage include weakness and muscle atrophy.
Note that every muscle group in the body requires both upper and lower motor neurones to function. The signs described above can occur in any muscle group, including the arms, legs, torso, and bulbar region.The symptoms described above may resemble a number of other rare diseases, known as "MND Mimic Disorders". These include, but are not limited to, multifocal motor neuropathy, Kennedy's disease, hereditary spastic paraplegia, spinal muscular atrophy and monomelic amyotrophy.
A small subset of familial MND cases occur in children, such as "juvenile ALS", Madras syndrome, and individuals who have inherited the ALS2 gene. However, these are not typically referred to as MND, but by their specific names
Currently there is no cure for ALS. The only drug that affects the course of the disease is riluzole. The drug functions by blocking the effects of the neurotransmitter glutamate, and is thought to extend the lifespan of an ALS patient by only a few months.
The lack of effective medications to slow the progression of ALS does not mean that patients with ALS cannot be medically cared for. Instead, treatment of patients with ALS focuses on the relief of symptoms associated with the disease. This involves a variety of health professionals including neurologists, speech-language pathologists, physical therapists, occupational therapists, dieticians, respiratory therapists, social workers, palliative care specialists, specialist nurses and psychologists.
Most cases of MND progress quite quickly, with noticeable decline occurring over the course of months. Although symptoms may present in one region, they will typically spread. If restricted to one side of the body they are more likely to progress to the same region on the other side of the body before progressing to a new region. After several years, most patients require help to carry out activities of daily living such as self care, feeding, and transportation.
MND is typically fatal within 2–5 years. Around 50% die within 14 months of diagnosis. The remaining 50% will not necessarily die within the next 14 months as the distribution is significantly skewed. As a rough estimate, 1 in 5 patients survive for 5 years, and 1 in 10 patients survive 10 years.Professor Stephen Hawking is a well-known example of a person with MND, and has lived for more than 40 years with the disease.
Mortality normally results when control of the diaphragm is impaired and the ability to breathe is lost. One exception is PLS, which may last for upwards of 25 years. Given the typical age of onset, this effectively leaves most PLS patients with a normal life span. PLS can progress to ALS, decades later. Around a third of all MND patients experience labile affect, also known as emotional lability, pseudobulbar affect, or pathological laughter and crying.
The incidence of MND is approximately 1–5 out of 100,000 people. Men have a slightly higher incidence rate than women. Approximately 5,600 cases are diagnosed in the U.S. every year. By far the greatest risk factor is age, with symptoms typically presenting between the ages of 50-70. Cases under the age of 50 years are called "young onset MND", whilst incidence rates appear to tail off after the age of 85.
Tentative environmental risk factors identified so far include: exposure to severe electrical shock leading to coma, having served in the first Gulf War, and playing Association football (soccer). However, these findings have not been firmly identified and more research is needed.
There are three "hot spots" of MND in the world. One is in the Kii peninsula of Japan, one amongst a tribal population in Papua New Guinea. Chamorro inhabitants from the island of Guam in the Pacific Ocean have an increased risk of developing a form of MND known as Guamanian ALS-PD-dementia complex or "lytico bodig", although the incidence rate has declined over the last 50 years and the average age of onset has increased.
Putative theories involve neurotoxins in the traditional diet including cycad nut flour and bats that have eaten cycad nuts.The search for a drug that will slow MND progression is under way. Agents that are currently in trials include ceftriaxone, arimoclomol, IGF-1, lithium and coenzyme Q10 to name but a few.
In conclusion, Motor Neurone Disease (MND) is a rare disease that affects the mobility of the body which in some cases will eventually lead to death. Currently, there is no known cure for this disease. However, we should not underestimate the people who have this disease as they can be strong and survive long enough to benefit the society such as Stephen Hawkings.


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