Motor Neuron Disease

Definition

“Motor Neuron Disease” is a term applied to a collection of diseases in which the motor neurons, both upper and/or lower, are progressively destroyed over time. This category includes diseases such as amyotrophic lateral sclerosis (ALS or Lou Gerhig's Disease), progressive muscular atrophy (PMA), primary lateral sclerosis (PLS), progressive bulbar palsy (PBP), and some forms of spinal muscular atrophy. One type of motor neuron disease, post-polio syndrome, can develop many years after a polio infection, producing similar symptoms.

Description

Motor neurons are those nerves in the body that are responsible for transmitting messages for movements such as those involved in moving, speaking, and breathing, among others. In motor neuron disease, the ability to transmit these messages for muscle movement may be progressively lost, making normal activities increasingly difficult as muscle activity declines. In some of these diseases, this progression may eventually result in death .

Demographics

In some cases, the disease may be inherited, and in other cases, they develop in an individual without prior family history. They occur worldwide, and the frequency of disease depends upon the type, though it is estimated to affect approximately five people per 100,000. For example, ALS (amyotrophic lateral sclerosis) is the most common motor neuron disease, affecting approximately 30,000 people in the United States at any one time, most of them Caucasian. It can affect people between the ages of 40 to 70. It is generally more common in men than in women, but is equally distributed between males and females among older age groups.

Causes and symptoms

The motor neurons of the body are responsible for carrying nervous system “messages” from the brain via the upper motor neurons, to the brain stem, and then to the spinal cord (lower motor neurons). These messages then travel to the muscles to create movement. In motor neuron disease, these “highways” for signal transmission are disrupted, affecting one's ability to move the voluntary muscles (the muscles a person can control).

This affects activities such as walking, breathing, or swallowing, but not the muscles used for activities such as the beating of the heart. The voluntary muscles can eventually become smaller (atrophy). In some cases, this can result in paralysis and death, as for some cases of ALS, where a person may lose the ability to breathe.

The symptoms of motor neuron disease will vary depending upon which type of disease is present and response of the individual, but in general, they may include the following:

• muscle weakness, often first appearing as dropping objects, difficulty buttoning shirts, climbing stairs, stumbling, “foot drop”
• fatigue
• stiffness or cramping of muscles
• twitching of muscles (fasciculation)
• difficulty speaking, swallowing, or breathing
• emotional changes

Motor neuron disease does not affect the sensory nerves responsible for smell, sight, hearing or taste, nor other functions such as those of the bladder and bowel. In general, it does not affect the intellect

It is not known specifically what causes motor neuron diseases that are not inherited, but it is believed to be a combination of genetic tendency, and exposure to agents in the environment, such as toxins and viruses . Research in this area is ongoing, with promising results. One gene NTE (neuropathy target esterase) has been implicated in the development of motor neuron disease, and studies are currently being performed to evaluate the interaction between such genes and factors in the environment to trigger the development of motor neuron disease.

Diagnosis

Motor neuron disease shares symptoms with many other diseases and conditions. Therefore, if motor neuron disease is suspected, it is very important to seek the advice of a qualified medical professional who specializes in the diagnosis of motor neuron disease. The tests conducted will depend upon the type of disease that is expected, but in general involves a combination of tests such as:

• neurological examination
• electromyography (EMG) involving electrical stimulation of muscles to look for abnormalities
• Nerve Conduction Velocity (NCV) tests
• spinal tap
• myelogram
• nerve and muscle biopsies
• Magnetic Resonance Imaging (MRI) to examine the brain and spinal column for abnormalities
• blood and urine tests for proteins, hormone levels, and heavy metal

Physicians will often require a complete medical history to try to determine what the symptoms are and when they first occurred. This will provide clues as to whether the symptoms are possibly due to some type of infection or perhaps another cause, so it is important for patients to list as much information as possible to assist in this process

Treatment

Currently, there is no real cure for or “treatment” for these diseases, though there are active, ongoing research efforts to determine the causes and search for treatments. At best, efforts can be made to help alleviate the symptoms, which can often be quite understandably anxiety-provoking in the patient.

One common treatment for symptoms is the mediation Rilutek, which has been shown to slow the progression of the disease by a few months. Other drugs may be administered to control muscles spasms and cramps, as well as other symptoms that may arise.

Nutrition/Dietetic concerns

As for any disease, it is important for patients to maintain a good, nutritionally balanced diet with adequate calorie intake. It may be beneficial to meet with a nutritionist to address dietary concerns. In particular, medical professionals may be able to provide guidance on how to cope with difficulties swallowing food, such as choosing thicker liquids over thin liquids, putting foods in the blender, and preparing shakes among other food choice recommendations. Also, people with motor neuron disease should avoid eating alone where one could choke. Having friends or family members close by who are trained in the Heimlich maneuver may be necessary.

For some patients, difficulties in swallowing (dysphagia) and chewing may result in severe impairment in the ability to consume food. For these patients, it may become necessary to have a feeding tube placed through the wall of the abdomen into the stomach (enteral feeding).

Therapy

A variety of therapy interventions can be applied to help patients cope with the day-to-day challenge of living with such potentially debilitating conditions. This requires a great deal of supportive care from a team of health care professionals, including the efforts of occupational, physical, rehabilitation, and other therapy specialists as indicated by the patient's condition. Compassionate efforts should be made to obtain the best possible quality of life for the patient throughout the various stages of illness, preserving the best possible mobility and enjoyment.

QUESTIONS TO ASK YOUR DOCTOR

• Are these symptoms indicative of a motor neuron disease, or could they be associated with some other condition?
• What tests may be needed, and are there any special preparations for these tests?
• What type of motor neuron disease is present, how much has it progressed, and what is the expected prognosis?
• What medications may be helpful?
• What type of medical follow-up is needed?
• What measures can be taken to improve the quality of life?
• What resources are available for coping with this disease?
• What resources are available for financial assistance?
• What plans need to be in place for a medical emergency?

The involvement of mental health specialists can not be over-emphasized, as this type of diagnosis can be incredibly challenging, sometimes requiring heroic coping skills. Some patients do not receive the needed counseling support as a standard of care, so it is imperative that care-givers take an active role in obtaining such support, not only for the patient, but for themselves. Depression and anxiety are common reactions to distressing symptoms, and assistance to help the patient and the patient's family cope with these symptoms is of extreme importance and must not be overlooked. Caregivers should not be hesitant to request support at the mental, emotional, and spiritual levels if required, and resources are available through various organizations to assist in these areas.

Prognosis

The prognosis for patients with a motor neuron disease is dependant upon what type of affliction they have, the age at which it occurred, individual factors and the course of the illness. For example, in the case of ALS, though the average life expectancy following diagnosis is from two to five years, approximately 20% will live more than ten years, and 10% more than ten years. There have been some individuals for which the progression has stopped.

KEY TERMS

ALS —Amyotrophic Lateral Sclerosis (Lou Gehrig's Disease)

Motor Neuron Disease —A collection of diseases in which the motor neurons, both upper and/or lower, are progressively destroyed over time affecting the voluntary muscles.

PMA —Progressive Muscular Atrophy

PBP —Progressive Bulbar Palsy

PLS —Primary Lateral Sclerosis

Post-polio Syndrome —A motor neuron disease that develops many years after polio

With this in mind, it is important for patients and there families to pursue support as needed and to focus upon maintaining the quality of life. The disease should be viewed in a step-wise fashion based upon the patient's condition, with a focus on living life to the fullest means possible.

Prevention

Some have suggested association with exposure to environmental factors regarding the development of motor neuron disease, but this is currently a topic of research, debate, and discussion. Research as to the underlying causes of motor neuron disease is ongoing.

Caregiver concerns

Care givers should be aware of the need for counseling and support, not only for the patient, but for other family members. There should be no hesitancy to request support to deal with this very challenging medical situation.

It may be wise to prepare an advanced directive for those patients who may have a poor prognosis, such that the patient's wishes for quality of life are honored.

Additionally, medical care for this condition can be costly, so it is important to inquire with insurers as to what items will be covered. Alternative resources may be available to assist with financial concerns through Medicare and the United States Social Security Administration, among others. Care givers should contact various support organizations on the web, which may be able to provide additional information.

Resources

books

Brust, J. Current diagnosis and treatment in Neurology. New York, McCraw Hill Companies, Inc., 2007.

ALS Association Maintaining good nutrition with ALS-Bethesda, 2007. http://www.alsa.org/files/cms/Resources/nutrition.pdf

other

http://hcd2.bupa.co.uk/fact_sheets/html/motor_neurone_disease.html

http://www.alsa.org/als/default.cfm?CFID=6045154&CFTOKEN=40320ce-f169be1a-117d-4249-9bca-f7c0b9f5ed93

http://www.alsmndalliance.org/

http://www.bmj.com/cgi/content/full/318/7191/1118

http://www.mayoclinic.com/health/amyotrophic-lateral-sclerosis/DS00359

http://www.medterms.com/script/main/art.asp?articlekey=17783

http://www.ninds.nih.gov/disorders/motor_neuron_diseases/motor_neuron_diseases.htm

organizations

ALS Association, 27001 Agoura Road, Suite 150, Calabasas Hills, CA, 91301-5104, 818-880-9007, 800-782-4747, 818-880-9006, http://http://www.alsa.org/.

Jill Granger M.S.