Introduction to Motor neuron disorder (MND)
Motor neuron disorder (MND) is characteristically a neurodegenerative disorder and is alternatively referred to as amyotrophic lateral sclerosis (ALS) . It is a degenerative disorder and typically has undefined and unknown aetiological characteristics. It is a progressive disorder and is typically associated a weakness of the motor functionality and is additionally associated with a dysfunction of the bulbar tissue . It is likely to result in premature death as well . Researchers and physicians have forever and especially in the 19th century have associated the weakness of the muscles and nervous tissue dysfunction with primary disorders of the muscle . Additionally, it may be associated with secondary loss of the integrity of neuromuscular tissues and cells . Such a dysfunction is similar to the dysfunction that results from a cut in the peripheral nerves. This is even likely in the cases of degeneration of motor neurones . Researchers have additionally observed that the motor neuron degeneration may be of different categories or types. They may selectively affect either the upper or the lower motor neurones causing selective dysfunction in either of these neuronal junctions . A condition in which there is a combination of the upper and lower neurone systems is known as amyotrophic lateral sclerosis or ALS. The terminology of ALS is more commonly used in the USA for diseases of the motor neurone dysfunction . The term ALS is used for most motor neurone dysfunction diseases irrespective of whether the upper or the lower motor neurones are involved. The term MND is used more commonly in the UK . MND occurs commonly in the middle or late life period. It is one of the most common diseases which onsets in the later adult life. There is no specific treatment protocol for the management of MND in adults. The substantial progression of the disease onset is not currently possible by any medication or known treatment procedure. The incidence rates of the disease is considerably high as it affects at least one or two individuals per 1, 00,000 individuals. The disease is predominantly prevalent in individuals who are middle aged or old. The mean age of disease onset is an average of 55 years old. However, occasional occurrences in younger individuals are possible.
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The disease is typically associated with progressive injury to the motor neurones. Additionally, the death of cells and groups of cells of the lower motor neurone are also associated with MND. The groups of cells of the lower motor neurone are present in the spinal cord and the brain stem regions in the individuals. The upper motor neurones of the motor cortex are mostly affected in the condition of MND. The affected individuals typically present with a combination of upper and lower signs of the motor neurone [3, 4, 21]. They also present with muscle weakness of a progressive nature. There is an occurrence of muscle wasting that primarily occurs due to the presence of brisk reflexes in a pathological manner. There is an eventual involvement of the muscles of the limb and the bulbar region. There may be occasional occurrences of several clinical variants of the disease which particularly affect the lower motor neurones predominantly. Progressive muscular atrophy and primary lateral sclerosis is predominantly associated with the upper and lower motor neurones. The occurrence of death is most often resulted from the failure of the respiratory organs which may be due to the presence of weakness in the ventilator muscles. The causes of the neurodegenerative process are not precisely predicted and they are unknown to research. The disease process particularly includes certain selectivity for the system of motor functionality in the human body. This type of sensitivity is particularly of a relative nature and is not observably absolute. Research and extensive analysis of clinical and pathological data have unravelled that the extra-motor sections of the central nervous system are additionally affected in these individuals. Therefore, research considers the condition as that involving multiple systems and the failure of motor neurones essentially occurs at the earliest stage. The motor neurones are affected severely in the early onset stages of the disease.
The degeneration of motor neurones is resulted from the presence of multiple gene products of different classes and of abnormal classifications. In most familial incidences of motor neurone disease, several gene mutations, particularly point mutations have been found to exist in most of these cases. The most common observation has been the mutation in the chromosome 21 that encodes copper and zinc superoxide dismutase (SOD1) (Cu/Zn) in the familial motor neurone disease. The primary function of SOD1 is the catalysis of conversion of radicals of the intracellular superoxide which are produced during the event of metabolism of normal cellular hydrogen peroxide. These hydrogen peroxide radicals are typically eliminated by scavenging enzymes that characteristically act on free radicals. SOD1 is a ubiquitous enzyme and undergoes expression in cells present throughout the body. However, the reason for the specific vulnerability of motor neurones to injury in the presence of several mutations lacks complete clarity. Motor neurones display a great degree of expression of the Cu/Zn superoxide dismutase enzyme in the compartments of the cells and the axons relative to the other cells of the nervous system. The mutant enzyme is able to generate a gain of function rather than a loss which results in a toxic event. One of the primary hypotheses for this gain of function is the likely abnormal handling of biochemical compounds such as hydrogen peroxide resulting in elevated formations of damaging hydroxyl radicals which are excessively damaging to the system. Additionally, the formation of nitrotyrosine residues on the intracellular proteins is indicated. Neurotoxicity is a common occurrence resulting due to the formation of intracellular aggregates of Cu/Zn superoxide dismutase which are abnormal and lead to adverse cellular biochemical effects along with a probable abnormal release of copper or zinc.
Oxidative stress is considered one of the most important causes of deterioration of neuronal function and age-related neurodegenerative disorders. The mutations of the Cu/Zn superoxide dismutase are known to cause damage to free radicals and several damaging biochemical changes leading to oxidative stress. An altered expression of the individual components of the defence systems of the intracellular antioxidants is a major reason for the presence of oxidative stress as indicated by post-mortem studies of the patients with as an attempt of the system to compensate for oxidative stress. The fibroblasts present in the fibroblast cells of the specimens of skin tissues of patients of familial and sporadic MND indicate an increased sensitivity to oxidative insults.
The primary excitatory transmitter of the human nervous system, glutamate, plays a vital role in the transmission of excitatory signals. The termination of the excitatory signal occurs when glutamate is taken out of the cleft of the synapsis by the means of several transporter proteins. They are primarily located in the perisynaptic glial cells. The stimulation of the receptors of the neuronal glutamate, if carried out in an excessive and abnormal manner typically results in the damage and the death of these cells. The mechanisms of the primary derangement of the homeostasis of intracellular moieties of calcium along with the excessive production of free radicals are also some of the effects of the derangement. Glutamate mediated toxicity is one of the primary factors that contribute to the injury of the cells in the condition of MND. One of the important findings of research indicates that one of the primary reuptake transporter proteins of glutamate is typically impaired in MND. The concentrations of glutamate are found to be abnormal in the extracellular fluid and the cerebrospinal fluid in a few cases of MND. Research has additionally found the presence of various RNA segments with abnormal splicing sequences. These encode the excitatory molecule of amino acid transporter 2. These have been found in the motor system in most cases of MND. Research has suggested that one of the major aetiological factors for the disease progression is the presence of a specific defect in the processing mechanism of the RNA molecule in the disease pathology. However, certain theories of disease progression suggest that the RNA segments which are alternatively spliced are typically found within the central nervous system.
Neurodegeneration of motor neurones
The neurons of the motor system are characteristically cells of a post-mitotic and fixed type. They do not have the retained capacity of replication. These cells tend to gradually reduce in number along with the process of aging. One of the important features of the MND condition is that only certain specific populations of the neurons of the motor system have additional vulnerability for degeneration. These cells are susceptible to acquire the disease process. Certain cell populations including the cell groups that are responsible for controlling the muscles of the extraocular region and the floor of the pelvic region are typically immune to the disease progression. Research has attempted to understand the particular features of the motor neuron that render it either resistant to disease development or vulnerable to acquiring the motor neuron disease condition. The features that mostly render the cells of the neuron susceptible to the disease include the following: The largest cells of the human system are those of the nervous system and thus the motor neurons that supply nerves to the distal lower limbs need to support the axonal processes that are up to one meter in length and thus the burden on these neurons is considerably high. This leads to an excessively high demand of energy in these cells. This requires a high level of mitochondrial activity along with the requirement for a robust and energetic system containing the cytoskeleton. This in turn poses the demand for a high content of intracellular material in the proteins of the neurofilament. Research has found evidence from human sources of tissue and several experimental animal models that the proteins of the mitochondria and the neurofilament are specific target sites for injury resulting in within the motor neurons. Another important feature is that most neurons of the motor system have specific features of the cellular composition that renders them susceptible to processes of a toxic nature that are mostly mediated by the calcium moiety. These processes are seen to result following the activation of the surface of their cells and the receptors present on the cell surface. Most of the neurones of the motor system are suggested to possess a particular profile for the receptors of d=glutamate which are permeable to calcium molecules. These are in fact different from the receptors of several groups present in other cell groups of the nervous system. Additionally, most motor neurons lack proteins that are responsible for intracellular buffering of calcium. These are responsible for protecting the various neurones from excessive increases in the calcium present in the cytosolic region. Motor neurones specifically contain a high extent of expression of perisomatic molecules of the excitatory amino acid transporter 2 moiety along with having a high expression rate of Cu/Zn superoxide dismutase enzyme.
Nursing care for patient with MND
The patients of MND have special needs and medical emergencies. The carers of these patients additionally have complex requirements in the caring of these patients. The common presentations include compromised respiratory mechanism and other emergency presentation. The needs of the patients are primarily addressed by the nurses. However, most often, their needs can be addressed adequately by the involvement of several teams and multidisciplinary units. The management of progressive neurological disorders is carried out by these multidisciplinary teams and their experience and skill set is crucial for the effective management of the challenges in the treatment procedures. The multidisciplinary team may involve a wide range of professionals including a physician, physiotherapist, counsellor or psychologist, dietician, community nurse, primary care general practitioner team, neurologist, gastroenterologist, occupational therapist, palliative care team, respiratory specialists, social service, speech and language therapist, and sociologist. The care protocol is carried out for 24 hours every day at the multidisciplinary centre or on an outpatient basis as the care provided needs to incessant. In the case of Mr. Chiswick, the progression of MND is at an advanced stage. Due to this, the care provided is mostly palliative care. The palliative care setup is also multidisciplinary in nature and the setup includes the afore-mentioned patients.
The role of the nurse is of specific importance in the multidisciplinary team. The nurse essentially needs to coordinate with the paramedics, physicians, and other related multidisciplinary teams to provide complete care to the patients. The role of the nurse is increasingly critical in the subsequent stages of the progression of MND and the progression of the disease process. The requirement of the support for the patient increases with time. The patients require more attention and time during the progression of the disease process. The nurse’s role extrapolates to the provision of support and assistance for the performance of many activities of daily life. Mr. Chiswick complains of inability to speak effectively or speech deficit. The nurse would then be required to coordinate with the speech and language therapists to provide the necessary care. Additionally, Mr. Chiswick experiences inability to walk and weakness due to which he has become wheelchair bound. The multidisciplinary team essentially includes wheelchair services as well and thus the nurse needs to assist in the provision of the physiotherapy and wheelchair services. Mr. Chiswick has been advised to undergo palliative care. The anxiety in the patient is a essential challenge to the care provided to him. Thus, the role of the psychologist is increasingly important. Mr, Chiswick experiences anxiety with a belief of being ‘given up on’ and believes that he is being driven to the process of death by lack of attempt of curative treatment. Thus, the appropriate counselling for the patient needs to be provided by the psychologist or the counsellor.
The nurse’s role is critical for educating the patient and his carer or the consequences of MND. The awareness of the disease progression and pathology of the disease is essential in the carer of the patient in order to appreciate the ceasing of curative medication. The role of the nurse extends from educating the patient and the carer to the coordinated provision of the multidisciplinary care options. The various multidisciplinary care services have to be provided with much coordination by the involvement of the nurse in the palliation. Palliative care mostly focuses on relief from pain and the requirement of the care protocol is to provide the essential aides for activities of daily life. Providing support to the patient for the performance of regular activities is an essential aspect of palliative care. The nurse is involved in both community caring as well as provision of care to hospitalised patients.
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The most important complications during the palliative care for a patient with MND include aspiration which can be potentially avoided by urging the patient to sit upright whilst consuming food. The carers of the patients also experience several emotional and physical demands during this stage; therefore, the nurse is expected to deal with the situation with empathy and provide adequate support to the carers. The up keeping of records of daily consumption of food and drinks, health and the moods of the patient, the pressure areas on the skin and treatment provided, if any, care at night, bathing, washing up, getting dressed and the aid provided, bowel habits of the patient and any reported constipation occurrences, and other recordable activities. Since Mr. Chiswick experiences difficulty in swallowing, the speech therapist needs to provide support in the swallowing activity. The dietician may additionally suggest any changes or dietary supplements with better ease of swallowing, and a diet to suit the patient can be prepared. In extreme cases, tube feeding can be undertaken. The possibility of choking has to be avoided by managing the position at the time of ingestion.
Person-centred nursing and multidisciplinary team care may be the best practice for patients with MND. Non-invasive respiratory assistance and reduction of pain at all stages of nursing and palliation are the most crucial for the improvement of the quality of life. The palliative care protocol includes the entire course of the disease development without involving only the final stage. Symptom control is crucial during the entire disease process. MND is associated with the damage of motor neurones and thus injury or trauma to the nerve has to be avoided. Since MND is a crippling and devastating condition, the role of nursing and care remains to enhance the independence and quality of life of the patients.
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