Lou Gehrig's disease: clinical features and management

Lou Gehrig's Disease: Etiology And Pathology

Amyotrophic lateral sclerosis is a motor neuron disease which causes muscular degeneration. ALS, also known as Lou Gehrig's disease, causes the death of the nerve cells in the central nervous system, resulting in a debilitating disruption of voluntary motor capabilities. As these nerve cells die off, the body becomes increasingly unable to send messages to its muscles, resulting in their immobility and atrophy. In spite of the relative awareness of this illness and a medical familiarity with its associated symptoms and course of diagnosis, it also remains vexing to medical science, which has only devised modestly effective methods of disease management and no ability to control or prevent the condition.

Etiology (causative agent):

The etiology of ALS is one of the most challenging areas with respect to our collective understanding of the disease. Though a number of causative agents have been suggested, most of those identified are either only speculative in nature or have been shown only to be true in a certain percentage of cases. Indeed, there are a number of types of ALS which appear in all likelihood to be differentiated by these causative factors.

For instance, familial ALS has been so named for the connection demonstrated between the genetic presence of ALS and its occurrence in offspring. Indeed, "in 10% of cases, ALS is transmitted in an autosomal-dominant manner [familial ALS (FALS)]" (Ray & Lansbury, 5701) This helps to act least connect the condition to some genetic indicators, which could be a clue in future research as to the genetic preconditions inciting the surfacing of the disease. It also points to the significantly heightened risk of familial ALS in the children of those who have familial ALS. For those that have what is called sporadic ALS, there is no observable connection between the condition's presence in family history and its occurrence in an individual. This demonstrates the complexity of identifying the etiology of ALS.

Still, even in familial cases, evidence suggests that heredity alone is not sufficient in understanding the cause of ALS. There have been some clues but at present, these have also only led to partial resolution on the subject. Indeed, a theory which is now popularly evaluated is that which identifies ALS as being the result of a genetic mutation. According to the study by Ray & Landsbury (2004), "the most commonly mutated gene, accounting for ?20% of all FALS, encodes superoxide dismutase type 1 (SOD1), a dimeric metalloenzyme that is rich in ?-sheet structure and contains copper- and zinc-binding sites, the former being critical for catalysis" (Ray & Lansbury, 5701) the hypothesis ventured on this subject indicates that the mutation on the SOD1 gene obstructs this from producing enzymes which are crucial in protecting the body from antioxidants. The deficiency in this area allows free radicals in the body to attach themselves to cells and proteins. These stifle motor neurons and gradually produce symptomatic evidence of the condition's presence.

In spite of compelling evidence that this genetic mutation can be identified in a number of cases, it too remains insufficient in accounting for all known cases of the condition. There are also causes to speculate that in many cases environmental toxins have played a part in the development of this condition. The higher demonstrated risk of various categories of individual, whether determined by profession, military service or geography tends to suggest that specific environmental conditions have also contributed to the cause of the disease. To what extent this is true remains uncertain, though numerous cases are available through general research endorsing the likelihood of this connection.

Diagnostic characteristics of the etiologic agent

Diagnosing ALS can be particularly difficult because the onset of symptoms may not demonstrate the immediate severity of the condition. Given the difficult which researchers have had in pinning down the etiology of the condition, identifying the etiologic agent does not typically occur. Instead, it is more common that the symptoms of the condition itself will reach a severe enough state to cause the physician to consider the possibility of ALS. In other words, it is less likely that the etiologic agent will produce an opportunity for diagnosis.

As WebMD reports, "it can be hard for your doctor to tell if you have ALS. It may not be clear that you have the disease until symptoms get worse or until your doctor has done more testing. To find out if you have ALS, your doctor will do a physical exam and will ask you about your symptoms and past health. You will also have tests that show how your muscles and nerves are working." (WebMD, 1) These tests may given the physician cause to observe the nerve cells where atrophy has occurred. Because ALS will generally prove debilitating to both upper and lower motor neurons, symptoms demonstrating a degeneration in both capacities will frequently be a tip-off that ALS is present.

Host/Intermediate host or Life

The individual who is host to this condition will have a limited life expectancy. ALS is a fatal disease which may run its course in a period of months or over a number of years. But as with the namesake of the condition in the U.S., Lou Gehrig, even those in peak physical condition may be struck by an aggressive advancement of the condition. Gehrig only survived two years following his diagnosis. This is demonstrative of the life-cycle for a disease that works its way through the body, eventually resulting in the failure to control basic life functions. According to current research "there is no cure for ALS, but treatment can help you stay strong and independent for as long as possible. It can also help you avoid other problems from ALS." (WebMD, 1)

Pathogenicity (include the pathology of the disease, specific toxins or other chemicals involved in the making of the disease)

Though the immediate effects of ALS become first present through the function of extremities, the pathogenicity of the disease demonstrates that an array of bodily systems are impacted and will produce evidence of the disease. Particularly, Waller (2006) indicates that "atrophy of the anterior horn cells and replacement of the large motor neurons by fibrous astrocytes (gliosis) causes the affected anterior and lateral columns of the spinal cord to become hard, hence the term 'lateral sclerosis.' Large neurons tend to be affected before small ones, but the general distribution of pathologic findings within the spinal cord should correlate with the clinical findings." (Waller, 1) This is also true of the brain, which will demonstrate atrophy in the motor cortex. In some ways, the pathology of the condition demonstrates the way that it invades and permeates the whole of the central nervous system.

In addition to the toxins which are found in the body due to the failure of the body to produce certain needed enzymes, we may also suggest the possibility that exposure to such chemicals as pesticides and chemical-based military weaponry could also be associated with ALS.