Overview
Daily activities such as chewing food, talking to others, writing on paper, or walking are all governed by motor neurons. These motor neurons are nerve cells that signal different parts of the body to complete their jobs efficiently. However, when these motor neurons are damaged, a person may experience muscle weakness, fatigue, slurred speech, and other symptoms –an indication of one of the motor neurone diseases (MND).
MND can affect anyone, but the symptoms start appearing after the person reaches 50 years and above. It is a rare and severe neurological group of disorders that lead to loss of brain and spine functionality. Men are more susceptible to motor neurone disease than women. It is not curable, but medical intervention helps manage the symptoms ensuring patients live for many years. Motor neurone disease shortens a person’s life expectancy and, eventually, leads to death.
This blog explains motor neurone disease, its types, symptoms, causes, and treatment options.
What are Motor Neurons?
Motor Neurons are a kind of nerve cell whose job is to send messages around the body so you can move. There are two main kinds:
- Upper motor neurons: Located in your brain, upper motor neurons send messages from there to the spinal cord.
- Lower motor neurons: Located in your spinal cord, the lower motor neurons transmit messages sent from the brain to your muscles.
When you have a motor neuron disease, the nerve cells die. Therefore, electrical messages cannot get transmitted from the brain to your muscles. With time, the muscles waste away. This is called, ‘atrophy.’
When this occurs, an individual loses control over movements and it gets harder to breathe, talk, swallow and even walk.
What is motor neurone disease?
Motor neurone disease is a blanket term that refers to a group of diseases that causes the loss of function of motor nerves in the spine and brain. The loss of function is progressive. It is a rare and severe neurodegenerative disease. Amyotrophic lateral sclerosis (ALS) is the most common form of MND.
Typically, the brain cells send signals to various cells in the spinal cord and muscles in the body to perform everyday functions – walking, chewing, talking, and others. But when the brain cells fail to send signals to different body parts, it may cause muscle stiffness and overactive reflex. Over time, individuals may find performing daily activities challenging, leading to motor neuron disease. Progressive bulbar palsy, progressive muscular atrophy, primary lateral sclerosis, spinal muscular atrophy, Kennedy’s disease, and post-polio syndrome are also a part of the motor neuron disease.
What are the types of motor neurone disease?
Motor neurone diseases are categorized if they are genetic, sporadic, and affect upper and lower motor neurons, or both.
The different types of diseases that belong to the group of motor neuron diseases are as follows:
- Amyotrophic Lateral Sclerosis (ALS): It is the most common form of MND. It affects upper and lower motor neurons responsible for walking, talking, chewing, swallowing, and breathing. As ALS progresses, a patient loses control of the affected muscles of the arms, legs, mouth, and respiratory system. Thus, resulting in muscle weakness, muscle atrophy, muscle twitches, and weakness.
In most cases, ALS can affect anyone. It usually develops between the age of 40-60 years. On average, patients with ALS live for 3 to 5 years after getting diagnosed. However, with supportive care, few patients continue to live for close to ten years.
- Primary Lateral Sclerosis (PLS): PLS is similar to ALS but affects only the upper motor neurons . Patients who are suffering from PLS experience muscle weakness and stiffness in the legs and arms, slow walking, and poor coordination and balance. As the disease progresses, it affects the quality of life, including slow walking and slurred and slow speech. However, unlike ALS, PLS is not fatal. It progresses slowly. Children are affected with primary lateral sclerosis, called juvenile primary lateral sclerosis.
- Progressive bulbar palsy (PBP) is a form of ALS. Progressive bulbar palsy damages the brain stem, causing frequent choking spells. Patients often struggle to speak, eat, swallow, and control emotions. Many patients with PBP, in due course, develop ALS.
- Pseudobulbar Palsy: It is similar to PBP. It affects the motor neurons that control the ability to chew, swallow and talk, and causes uncontrollable laughter and crying.
- Progressive muscular atrophy: It is a rare disorder that affects the lower motor neurons in the spinal cord causing slow but gradual muscle wasting, particularly in the arms, legs, and mouth. It can be inherited or sporadic. Progressive muscular atrophy can develop into ALS.
- Spinal muscular atrophy (SMA): A defective gene called SMN1 causes spinal muscular atrophy (SMA). The gene is responsible for producing proteins that protect the neurons – without the neurons may die. It develops in children and causes weakness in the trunk, legs, and arms. It is an inherited disease and has four types. They are as follows:
- Type 1: It is also known as Werdnig-Hoffman disease. It affects babies at around 6 months of age. Children with this disease cannot hold their heads up or sit on their own. The symptoms include weak muscle tone, poor reflexes, and trouble swallowing and breathing.
- Type 2: This type affects children between 6-12 months. Affected children can sit but cannot stand or walk independently and may find breathing difficult.
- Type 3: It is also called Kugelber-Welander disease. It develops between ages 2 and 17. It affects the child’s gait, walking, running, posture, and ability to stand or climb stairs. Other symptoms include a curved spine and shortened muscles or tendons around the joints.
- Type 4: It affects people after 30 years. Patients with this type may experience muscle weakness, shaking, twitching, or breathing difficulties. This type of disorder typically affects the muscles in the upper arms and legs.
- Kennedy’s disease: It is an inherited disease that affects only men. Women can be carriers but are not affected by the disease. The woman with the defective gene has a 50% chance of passing it on to her son. Hand tremors, muscle cramps and twitches, weakness in the facial muscle, arms, and legs, troubled swallowing, difficulty speaking, enlarged breasts, and decreased sperm count are symptoms of Kennedy’s disease.
- Post-polio syndrome (PPS): Polio survivors get affected by this kind of muscle neuron disease after decades of recovering from the initial illness. It causes severe damage to the motor neurons. Fatigue, muscle and joint weakness, gradual worsening of pain, muscle atrophy and twitches, reduced tolerance to cold, and difficulty in breathing, swallowing, or sleeping could be symptoms of post-polio syndrome. It is not fatal. It is estimated that 25 to 50% of polio survivors develop PPS.
- Respiratory insufficiency: The patient cannot breathe enough oxygen and expel carbon dioxide. Breathlessness, shortness of breath when lying down, repeated chest infections, disturbed sleep, decreased concentration, poor memory, confusion, morning headaches, and fatigue are symptoms of respiratory insufficiency.
What are the symptoms of motor neuron disease?
Motor neuron disease gradually progresses in three stages, each stage having different symptoms and varying severity.
Early stage
In the early stage, the symptoms develop gradually and are confused with other health conditions. The symptoms depend on the type of MND and its severity. It affects the arms, legs, mouth, and respiratory system. The symptoms are as follows:
- A weakened grip, resulting in difficulty picking and holding things
- Fatigue
- Muscle pain, cramps, and twitches
- Slurred speech
- Weakness in the legs and arms resulting in clumsiness and stumbling
- Difficulty breathing, shortness of breath, and swallowing
- Unacceptable emotional responses, such as laughing or crying
- Increased weight loss
Middle stage
As the disease progresses, the symptoms worsen. Patients may experience the following:
- Shrinkage of muscle
- Joint pain
- Challenges in moving
- Drooling due to difficulty swallowing
- Uncontrolled yawning leads to jaw pain
- Changes in personality and emotional changes
- Troubled breathing
Advanced stage
In the advanced stage of ALS, patients require assistance to move, eat, breathe, or perform all of the above functions. It is a life-threatening disease causing breathing issues. Breathing issues are the most common cause of death in ALS patients.
When to see a doctor?
A person should consult their doctor if they notice symptoms of motor neurone disease, such as muscle weakness. Early and proper diagnosis is crucial for the patient to get needed care and support.
What are the causes of motor neurone disease?
Research studies show that nearly 10% are hereditary, and 90% develop randomly. The exact cause of developing motor neurone diseases is unknown. However, the National Institute of Neurological Disease and Stroke reports that the reasons may also be genetic, toxic, viral, and other environmental factors.
What are the risk factors of motor neurone disease?
Motor neurone disease can occur in adults and children. It manifests as spinal muscular atrophy in children due to specific genetic mutations. The symptoms may appear immediately at birth or during early childhood. However, adults are more likely to develop MND without any family history, and the symptoms may occur after age 50.
How is motor neurone disease treated?
Currently, motor neurone disease is incurable. But treatment can assist in reducing the impact of the symptoms. The following are the treatment options available for patients:
Medications
- Riluzole is the first medicine approved by the US Food and Drug Administration (FDA) to treat Amyotrophic Lateral Sclerosis ALS. During the clinical trials, patients who used the medication lived nearly 10 per cent longer than those who didn’t receive the medicine. However, the medicine does not reverse the already-caused damage. It has been shown to decrease the release of glutamate and block sodium channels – both may protect against motor neuron damage.
- Edaravone is another drug that is FDA-approved to treat, slow physical function decline, and prevent disease progression in ALS patients. The medicine is administered intravenously .
- Nusinersen: It is the first FDA-approved drug to treat SMA in children and adults. An injectable medication increases the SMN protein required for proper muscle and nerve function. The fully functional human SMN gene with a virus is delivered to patients that target motor neurons, improving their muscle movement and function, and increasing their chances of survival.
- Muscle relaxers: Medicines, including baclofen, tizanidine, and benzodiazepines, may help reduce muscle stiffness and spasms.
- Botulinum toxin: The injection may help treat muscle stiffness by weakening the overactive muscles. The medicine is also injected into the salivary glands to prevent drooling. Excess saliva can also be treated with medication such as amitriptyline, glycopyrrolate, and atropine.
Supportive therapies
- Physical therapy and rehabilitation: These treatments help improve posture, stop joint immobility, and slow muscle weakness and atrophy. Patients can be relieved from stiffness and increase their range of motion and circulation through various stretching and strengthening exercises. In severe cases, patients may need additional speech, chewing, and swallowing therapy. Assistive devices help patients gain some independence. These devices include supports or braces, orthotics, speech synthesizers, and wheelchairs.
- Correct nutrition and a balanced diet: A balanced diet with proper nutrition are crucial for maintaining weight and strength. People finding chewing and swallowing difficult may need a feeding tube.
- Ventilators: Doctors recommend non-invasive positive pressure ventilation to prevent sleep apnea. Sometimes, assisted ventilation during the day may be required in case of muscle weakness in the neck, throat, and chest.
Conclusion
Motor Neurone Disease is a rare condition that is overwhelming to deal with. However, proper therapy, treatment, and medication can manage the symptoms.
Frequently Asked Questions (FAQs)
How is MND diagnosed?
The following are some of the tests that help diagnose MND
- Electromyography detects electrical energy in the muscle
- Nerve conduction study tests how efficiently the nerves transmit signals to the muscles
- MRI scan detects other possible reasons that cause the symptoms
- Blood and urine test
- Muscle biopsy to rule out other conditions
What are the tips for living with ALS?
The following are the tips that help to live with ALS easily:
- Socializing with friends and family is crucial, and actively participating in several activities helps.
- Be a part of a support group to share experiences and gain valuable insights
- Make necessary arrangements at home for effective movements .
- Plan ahead for the future, such as making arrangements for patient care.
