The most common form of motor neuron disease is also known as amyotrophic lateral sclerosis (ALS), which is a condition in which motor neurons dominate our muscle movements. When motor neurons become diseased, the muscles slowly atrophy and die, which in turn affects the respiratory system, resulting in paralysis of the limbs and difficulty swallowing and breathing. In the United States, ALS is also known as Lou Gehrig’s disease, named after the American baseball player who died of the disease in 1941. In the United Kingdom and elsewhere in the world, ALS is often referred to as motor neuron disease, based on the cells lost in the disease.
I. Overview.
ALS usually occurs in middle-aged and older people (on average, in their 50s) or later, although it also occurs in younger people and even children. Some genetic types of ALS can cause symptoms to appear in young adults. Men are more likely to develop ALS than women by a ratio of 1.2:1.
II. Possible etiology.
To date, the cause of the disease is unclear. The following possible causes are being studied by ALS experts.
1. Free radicals.
2. Excess glutamate.
3. accumulation of neurofilaments.
4. Mitochondrial defects.
5. Apoptosis.
6. Abnormal immune system.
7. Viruses and other infectious substances.
8. Toxins: Long-term exposure to agricultural drugs such as pesticides may, in some cases, be the cause of ALS.
9. Genes.
10. Other etiological factors.
III. Clinical classification of motor neuron diseases.
1. Juvenile-type remote muscular atrophy (JDSMA)
JDSMA is a form of muscular dystrophy of the palms of the hands, which will not develop into a full-blown muscular dystrophy. It is often called “Hirayama disease” in China.
2, spinal muscular atrophy (SMA)
It is mainly progressive muscle atrophy of the limbs of the hands and feet, and most of the time it does not invade the muscles of breathing and swallowing, and has a long disease course.
3. Lateral sclerosis of the spinal cord (ALS/MND)
This is the most common motor neuron disease, 80% of motor neuron diseases belong to this type, this type can be divided into two categories: one starts with muscle atrophy of the limbs and then invades the muscles of swallowing and breathing; the other starts with muscle atrophy of swallowing and breathing and spreads to the limbs, this kind of motor neuron disease is aggressive and has a poor healing process.
4.Lower motor neuron syndrome (LMN)
It is an autoimmune disease in which the muscles of the hands and feet are mainly atrophied and the tendon reflexes of the extremities are normal or disappear. Chemotherapy and plasma dialysis may be helpful for this type of motor neuron disease.
Disease development process.
1. The beginning of the disease: At the beginning of the disease, there may be a sudden inability to hold chopsticks in the hand, or occasional falls for no apparent reason when walking, without any obvious symptoms.
2. Difficulty in work: The hands and feet are obviously weak and even atrophied, and although they can still take care of themselves, they are already handicapped in the workplace.
3.Difficulty in daily life: the disease process into the middle, hands or feet, or hands and feet at the same time has been severely impaired, life has been unable to take care of themselves, such as unable to walk, dress themselves, hold dishes, and speech has been slightly unclear expression situation.
4. Dysphagia: The disease process has entered the middle and end stage, the speech has become seriously unclear, the limbs are almost completely weak, and even liquid food is easy to choke when eating, which often leads to aspiration pneumonia if the nasogastric tube is not inserted for feeding.
If the patient chooses to undergo tracheotomy when he/she has difficulty in breathing, he/she should be admitted to a regional respiratory care center or receive home care.
Often, the initial phase of ALS begins with persistent weakness or spasticity in one arm or leg, leading to difficulty moving that part of the limb; or the muscles that control speech or swallowing, leading to difficulty functioning those muscles. Patients usually ignore these problems at this stage, or visit a doctor who does not relate to this. However, if this is indeed ALS, it does not stop there. Often it will expand from one part of the body to another, often adjacent to it. In this way, the problem becomes so serious that it can no longer be ignored.
A complete medical history, family history and physical examination are the starting points for a neurological examination. The patient will undergo simple, indoor muscle and nerve function testing.
If ALS cannot be ruled out at this point, a further electromyography (EMG) is usually performed. This test has some similarities to the more familiar electrocardiogram (EKG), which measures the signals between nerves and muscles and the electrical activity within the muscles to determine if it is the type consistent with ALS. If so, additional tests may be performed.
Additional tests may include imaging of the spinal cord and brain (usually magnetic resonance imaging). Sometimes it also includes a cerebrospinal fluid test (spinal tap or lumbar puncture), which is performed by inserting a needle between two low vertebrae.
Blood tests are also performed to rule out the possibility of other diseases. In some cases, a muscle biopsy (removal of a small sample of muscle after local anesthesia) is also performed.
With the exception of genetic testing, which can identify a small percentage of ALS, the diagnosis of ALS is a “stepwise exclusion” process. This means that the diagnosis of ALS is made only after all other possibilities have been ruled out by special tests.
Some of the conditions that resemble ALS are forms of muscular dystrophy, such as neurological spinal myelomeningocele and adult onset spinal muscular dystrophy, neuromuscular transmission disorders such as myasthenia gravis and spinal cord or brainstem compression due to tumors or malformations.
If you were diagnosed with ALS in a small hospital or without extensive examination, it is worthwhile to visit a specialist in a large hospital again.
V. Diagnosis.
The diagnosis of motor neuron disease must be made with extreme caution! A large number of patients with motor neuron disease are clinically misdiagnosed as cervical spondylosis and undergo surgery. This will not only increase the financial burden on the patient and family, but will also directly aggravate the condition, knowing that trauma such as surgery can cause a sharp turnaround in motor neuron disease and significantly shorten the survival period.
On the other hand, a considerable number of clinicians will misdiagnose diseases with very similar clinical manifestations such as Kennedy’s disease, multifocal motor neuropathy (MMN), chronic motor axonal neuropathy (CMAN), monoclonal proliferative disease, etc. as motor neuron disease, allowing patients to take expensive drugs such as LIRUZUO orally, causing unnecessary psychological burden, economic waste, and also delaying the disease and missing the The best time for treatment will be missed. For this reason, we hope to have the diagnosis made by a specialist at an extremely specialized hospital. This is extremely important!
Brief diagnostic criteria for motor neuron disease
(a) The following neurological symptoms and signs must be present
1, lower motor neuron lesion characteristics (including the current clinical performance is normal, EMG abnormalities)
2, upper motor neuron lesion characteristics
3.Progressive disease
(B) Diagnostic criteria of ALS
1.Confirmed ALS: Signs and symptoms of upper and lower motor neuron lesions in three of the four regions of the body (brain, cervical, thoracic, and lumbosacral innervation areas).
2.Proposed ALS: Signs and symptoms of upper and lower motor neuron lesions in two regions, with upper motor neuron damage and progression to the upper end.
3.Probable ALS: signs and symptoms of upper and lower motor neuron lesions in one region, or signs of upper motor neuron lesions in two or three regions.
(c) The following criteria support the diagnosis of ALS
One or more muscle bundle tremors; EMG suggesting anterior horn cell damage; normal MCV and SCV but prolonged distal latency and low wave amplitude; no CB (conduction block).
(iv) Signs and symptoms that should not be present in ALS.
Sensory: sphincter, visual and ocular muscles, autonomic nerves, extrapyramidal system, Alzheimer’s disease, signs and symptoms of ALS-like syndromes that can be explained by other diseases
(e) The following tests may help in the diagnosis
EMG, ENG, SCMEMG, MRI of the brain and spinal cord, muscle biopsy.