Medical Guide for Motor Neuron Disease (Introduction) http://www.mingyihui.net/article_415.html What is motor neuron disease?
Motor Neuron Disease (MND) is a group of diseases with unknown causes, selectively damaging the anterior horn of the spinal cord and the motor nuclei of the brainstem. It is a slowly progressing neurodegenerative disease. Clinically, it manifests as coexistence of upper and lower motor neuron paralysis in the limbs, without affecting the sensory system, autonomic nervous system, and cerebellar function.
What are the manifestations of motor neuron disease? Are there any special symptoms?
What are the early symptoms of motor neuron disease?
The clinical symptoms depend on the location of the most severely affected part of the nervous system and vary according to the lesion site. The specific types are as follows:
1. Amyotrophic Lateral Sclerosis (ALS): The most common type. Onset age is between 40-50 years, more common in males than females. The onset is insidious and progresses slowly. Clinical symptoms often start in the distal part of the upper limb, manifesting as hand muscle atrophy and weakness, gradually progressing to the forearm, upper arm, and shoulder girdle; the atrophied muscles show obvious fasciculations; at this time, the lower limbs exhibit signs of upper motor neuron paralysis, characterized by increased muscle tone, hyperactive tendon reflexes, and positive pathological signs. Symptoms usually progress from one side to the other. The damage is basically symmetrical. As the disease progresses, symptoms of medullary and pontine nerve motor nucleus damage may gradually appear, such as tongue muscle atrophy and fibrillation, dysphagia, and slurred speech; in the late stage, it affects the neck muscle strength and respiratory muscles. The main clinical feature of ALS: simultaneous damage to both upper and lower motor neurons.
2. Progressive Bulbar Palsy: The lesion is limited to the anterior horn cells of the spinal cord and does not affect the upper motor neurons. This type can be divided according to the age of onset and lesion site:
(1) Adult type (distal type): Common in middle-aged men, starting from the distal part of the upper limb, developing from the hand towards the proximal part, with obvious muscle atrophy and weakness, decreased tendon reflexes, and muscle fasciculations, which can develop to the lower limbs or neck muscles, causing respiratory paralysis. In very few cases, it can develop from distal to proximal.
(2) Juvenile type (proximal type): Most cases start during adolescence or childhood, with a family history, being either autosomal recessive or dominant inheritance. Clinically, it presents with pelvic girdle and proximal lower limb muscle weakness and atrophy, unsteady gait when walking, abdominal protrusion when standing, followed by shoulder girdle and proximal upper limb muscle weakness and atrophy, with anterior horn stimulation manifestation (muscle fasciculations), difficulty getting up from supine position.
(3) Infantile type: An autosomal recessive genetic disease, occurring within the mother's body or within one year after birth. Clinically, it presents with muscle weakness and atrophy in the limbs and trunk. Therefore, fetuses who develop the disease in the mother's body have significantly reduced or absent fetal movements, and newborns have weak cries, obvious cyanosis, generalized flaccid muscle weakness and atrophy. Atrophy starts from the pelvic girdle and proximal lower limbs, progressing to the scapular girdle, neck, and distal parts of the limbs. Cranial nerve-controlled muscles are also easily damaged. However, fasciculations are rarely seen clinically. Intellectual, sensory, and autonomic nervous functions are relatively intact.
3. Progressive Muscular Atrophy: More common after the age of 40, early lesions present symptoms of bulbar damage, patients may experience tongue muscle atrophy and fibrillation, dysphagia, choking while drinking water, and slurred speech. Later, due to damage to the pons and corticobulbar tracts, pseudobulbar palsy symptoms may occur, such as hyperactive tendon reflexes and positive pathological reflexes in the limbs if the corticospinal tract is involved.
4. Primary Lateral Sclerosis: More common in middle-aged men, clinically presenting as slowly progressive upper motor neuron paralysis in the limbs, muscle weakness, increased muscle tone, hyperactive tendon reflexes, and positive pathological signs. Generally, there is little muscle atrophy, and it does not affect sensation and autonomic nerve function. It can affect the corticobulbar tracts of the brainstem, presenting as pseudobulbar palsy.
Clinically, it presents as slowly progressive spastic muscle weakness; in primary lateral sclerosis, it is muscle weakness in the distal parts of the limbs, while in progressive pseudobulbar palsy, it mainly involves the muscles controlled by the posterior cranial nerves. Muscle fasciculations and atrophy may occur many years later. These diseases usually cause complete loss of patient activity after several years of progression.
After knowing the manifestations of motor neuron disease, what checks should we do?
What tests should be done for motor neuron disease?
1. Cerebrospinal fluid examination is basically normal.
2. Electromyography shows spontaneous potentials, normal nerve conduction velocity.
3. Muscle biopsy shows neurogenic muscular atrophy.
4. Head and neck MRI may be normal.
After confirming the diagnosis through tests, how should we treat it?
Precautions before treating motor neuron disease:
There is no special treatment yet. Acupuncture and traditional Chinese medicine can be used, with some efficacy. In recent years, drugs applicable in clinical practice include: ① Riluzole, 50mg, taken orally every 12 hours; ② Lamotrigine, starting with 25mg daily, gradually increasing to 100mg/d, clinical studies indicate that this drug can improve symptoms and delay progression, but cannot change the outcome; ③ Immunosuppressants, commonly used drug cyclophosphamide 200mg intravenous drip, online appointment registration, every other day or twice a week, total amount 3-4g for one course, partially effective for motor neuron disease; ④ Nerve growth factor is also applied, but its efficacy is uncertain.
For those with respiratory muscle paralysis, tracheotomy and artificial assisted respiration should be performed as soon as possible. Select appropriate antibiotics for pulmonary infections. For those with stiff limbs, physical therapy can be given, along with oral administration of baclofen 5-10mg, 2-3 times/day to improve symptoms. Carbamazepine or phenytoin sodium can be taken orally for painful spasms.
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