Motor neuron disease

Introduction to motor neuron disease Motor neuron disease (MND) is a group of unexplained causes, which selectively damage the anterior horn of the spinal cord and the motor nucleus of the brainstem, and slowly progress to the degenerative diseases of the nervous system. The clinical manifestations are muscle atrophy, muscle weakness, and upper limbs. The lower motor neurons coexist, without involving the sensory system, characterized by autonomic and cerebellar functions. Such as: unclear speech, difficulty swallowing, difficulty in activities, difficulty breathing, etc. Finally, the patient died because of the inability to breathe when the patient was conscious. Therefore, this kind of patient is also called "gradually frozen person." basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: amyotrophic lateral sclerosis

Cause of motor neuron disease

Gene abnormalities (20%):

There is a family history called familial motor neuron disease. In recent years, genetic abnormalities of superoxide dismutase have been found in this group of family members with motor neuron disease, and it is believed that this group may be the disease. The reason is that with the application of experimental motor neuron disease model in the active immunization of animals with spinal cord anterior horn cells, the anti-GM1 antibody in serum and cerebrospinal fluid, the detection rate of anti-calcium channel antibody and the certain therapeutic effect of immunosuppressive therapy have been The theory of autoimmune mechanisms has received much attention.

Abnormal immune function (40%):

Immune function refers to the body's resistance to disease. The immune function of the body is completed by the interaction of lymphocytes, monocytes and other related cells and their products. The immune function is the function of the immune system based on immune recognition. Immune abnormalities can cause the disease.

Motor neuron disease prevention

As the cause of this disease is unknown, there are no special precautions. Anyone who is involved in the cause of the disease, such as heavy metal contacts, should have regular health checks, paying particular attention to changes in muscle strength for early detection and early treatment. Usually, you should pay attention to physical exercise and emotional adjustment, keep your mood happy, avoid irritating and other mental stimuli. After middle age, it is better to live alone, reduce sexual intercourse, diet should be light, creamy and spicy. It is appropriate to prevent adverse factors such as spleen and kidney yang deficiency, liver and kidney yin deficiency.

Motor neuron disease complications Complications amyotrophic lateral sclerosis

The disease is a progressive disease, but the course of different types of patients is different, even if the same type of patients progressed slowly, the average course of amyotrophic lateral sclerosis is about 3 years, and the progress is fast or even after the onset 1 Can die within the year, the progress of slow progress can sometimes reach more than 10 years, adult type of spinal muscular atrophy generally develops slowly, the course of disease often reaches more than 10 years, primary side sclerosis is rare in clinical practice, generally slow development, death More due to ball paralysis, respiratory muscle paralysis, combined with pulmonary infection or systemic failure.

Symptoms of motor neuron disease Common symptoms Muscle tremor muscles beating sporty excitement or inhibiting cough, swallowing difficulty, reflexes, muscle atrophy, purpura

symptom

The onset is slow and the course of the disease can be subacute. The symptoms depend on the damaged part. Because motor neuron disease selectively invades the spinal anterior horn cells, the brain in the cranial nerve motor nucleus, and the brain motor cortex pyramidal cells, pyramidal tracts, so if the lower grade motor neurons are dominant, called progressive spinal muscular atrophy If the disease is higher than the upper motor neuron, it is called primary lateral sclerosis; if the upper and lower motor neuron damage exists at the same time, it is called amyotrophic lateral sclerosis; if the lesion is medullary motor neuron degeneration The subject is called progressive medullary paralysis. Clinically, progressive spinal muscular atrophy and amyotrophic lateral sclerosis are the most common.

The main manifestations of this disease, the earliest symptoms are more common in the hand part, the patient feels that the finger movement is weak, stiff, clumsy, the hand muscles gradually shrink, visible muscle bundle tremor. The distal extremities are progressive muscular atrophy. About half of the cases are early in the upper limbs. The size of the hand muscles is atrophy. Later, it extends to the forearm muscles, even the pectoralis major muscles. The back muscles can also shrink, and the calf muscles can also shrink. Muscle atrophy, limb weakness, high muscle tension (stretching sensation), muscle bundle tremor, difficulty in movement, breathing and swallowing disorders. For example, early bilateral bilateral pyramidal tracts may have paraplegia of both lower extremities.

First, the lower motor neuron type:

More than 30 years old. Usually with small muscle weakness in the hand and muscle gradual atrophy, it can spread to one side or both sides, or from one side to the opposite side. Due to the atrophy of the size of the fish muscles, the palms are flat, and the interosseous muscles are atrophied and have claw-like hands. Muscle atrophy is extended upwards, gradually invading the forearm, upper arm and shoulder strap. The fasciculation is common and can be limited to certain muscle groups or widely existed, and it is easy to induce by hand tapping. A small number of muscle atrophy begins with the tibialis anterior and tibialis musculature of the lower extremities or from the extensors of the neck, and can also begin with the proximal muscles of the upper and lower extremities.

Cranial nerve damage is often the earliest invasion of the lingual muscles, with atrophy of the tongue muscles, accompanied by tremors. Later, the sputum, pharynx, laryngeal muscles, and masticatory muscles are gradually weakened, resulting in unclear articulation, difficulty in swallowing, and weakness in chewing. Ball paralysis can occur after the first symptom or following atrophy of the limb.

Late muscles can be atrophied, so that bedridden, and respiratory dysfunction caused by respiratory muscle paralysis.

If the lesion mainly affects the anterior horn of the spinal cord, it is called progressive spinal atrophy, and because it begins in adulthood, it is also called adult spinal muscular atrophy. It is different from infants and adolescents in infancy or juvenile onset. Type of spinal muscular atrophy, the latter two have family genetic factors, clinical manifestations and disease course are also different, and will not be detailed.

Second, the upper motor neuron type:

It manifests as weakness, tightness, and inability to move. Symptoms start with both lower extremities and later affect both upper limbs, and the lower limbs are heavy. The limbs are weak, the muscle tension is increased, and the walking is difficult. The squatting gait is squatting, the sputum reflex is hyperthyroidism, and the pathological reflex is positive. If the lesion involves the bilateral cortical brain stem, pseudo-ball paralysis symptoms, clear pronunciation, swallowing disorder, hyperthyroidism hyperthyroidism. The disease is rare in clinical practice, and it usually starts in adulthood, and the progress is generally slow.

Third, the upper and lower motor neurons mixed type:

Usually the hand muscle weakness, atrophy as the first symptom, usually from one side to the opposite side, with the development of the disease, the upper and lower motor neurons mixed damage symptoms, called amyotrophic lateral sclerosis. In the late course of the disease, the muscles of the whole body are thin and atrophy, so that the head can not be lifted, breathing is difficult, and bedridden. The disease is mostly in the 40 to 60 years old, about 5 to 10% have a family history, and the progress of the disease is different.

Type

According to the most severely damaged nervous system, the clinical symptoms vary according to the location of the lesion. The specific classification is as follows:

1. Amyotrophic lateral sclerosis (ALS): the most common, the age of onset is 40-50 years old, more men than women, the onset of disease is hidden, slowly progressing, clinical symptoms often start at the distal end of the upper extremity, showing the hand Muscle atrophy, weakness, gradually forward arm, upper arm and scapula belt development; atrophic muscle has obvious fasciculation; at this time, the lower limbs are upper motor sputum, showing increased muscle tone, hyperreflexia, pathological signs positive, symptoms Usually from one side to the other side, the basic symmetry damage, with the development of the disease, can gradually appear medulla, cerebral palsy nerve movement nuclear damage symptoms, tongue muscle atrophy, dysphagia and speech vague; late influence on head muscle strength And respiratory muscles, the main clinical features of ALS: simultaneous damage of upper and lower motor neurons.

2, progressive medullary paralysis: the lesion is limited to the anterior horn cells of the spinal cord, does not affect the upper motor neurons, this type can be divided according to the age of onset and lesions:

(1) Adult type (distal type): occurs mostly in middle-aged males. It starts from the distal end of the upper extremity and develops from the hand to the proximal end. There is obvious muscle atrophy and muscle weakness, sputum reflexes, and muscle fasciculation. Development to the lower limbs or neck muscles, causing respiratory paralysis, very few can develop from the distal to the proximal.

(2) juvenile type (near-end type): most of them start from adolescence or childhood, have a family history, are autosomal recessive or dominant inheritance, clinically with pelvic and proximal limb muscle weakness and muscle atrophy, walking When the gait is unstable, the abdomen is convex when standing, and the scapula and the proximal muscles of the upper limbs are weak and muscle atrophy, and there is a anterior horn stimulation (muscle beam tremor), and the supine position is not easy to get up.

(3) Infant type: It is an autosomal recessive genetic disease, which occurs in the mother or within one year after birth. The clinical manifestations are muscle weakness and atrophy of the limbs and trunk. Therefore, the fetus in the mother is significantly reduced in fetal movement. Or disappear, the child with morbidity after birth is weak, obvious purpura, systemic flaccid muscle weakness and muscle atrophy, atrophy begins with the pelvic and proximal limbs, develops to the scapula, the neck and the distal extremities, cranial nerve innervation The muscles are also extremely vulnerable, but the muscle tremors are rare in the clinic, and the intelligence, sensory and autonomic functions are relatively intact.

3, progressive muscular atrophy: after the onset of 40 years old, early symptoms of medullary lesions, patients may have atrophy of the tongue muscle fibrillation, difficulty swallowing, drinking water cough and language vague, etc., late damage to the pons and brain The brain stem bundle can be combined with the performance of pseudobulbar paralysis, such as hyperactivity of the limbs and the pathological reflex.

4, primary lateral sclerosis: middle-aged males have more morbidity, clinically slow-developing limbs of motor neurons, muscle weakness, increased muscle tone, hyperreflexia and pathological signs, generally less muscle atrophy, Does not affect the sensory and autonomic function, can invade the cortical medullary bundle of the brain stem, showing pseudobulbar paralysis.

The clinical manifestations are the slow progression of tonic muscle weakness, which is the muscle weakness of the distal part of the limb in primary lateral sclerosis. In the progressive pseudobulbar medulla, the muscle weakness of the posterior cranial nerve is predominant. Muscle twitching and muscle atrophy can occur many years later. These diseases usually result in a total loss of patient mobility after several years of progression.

Motor neuron disease examination

1. Examination of cerebrospinal fluid: cerebrospinal fluid pressure measured after puncture, 0.78-1.96 kPa (80-200 mm water column) for adults in the lateral position, 0.39-0.98 kPa (40-100 mm water column) for infants, and 0.098- for newborns. 0.14 kPa (10-14 mm water column). When observing the initial pressure, attention should be paid to the presence or absence of respiratory pulsation in the cerebrospinal fluid level (with a respiratory rate of 0.098-0.197 kPa (10-20 mm water column pulsation) and pulse pulsation (with a pulse of 0.02-0.039 kPa (2-4 mm water column). Liquid level beat). Basically normal.

2, EMG examination: EMG is to describe the functional state of the neuromuscular by describing the biological current of the neuromuscular unit activity, in order to combine the clinical diagnosis of the disease, the use of electromyography can help distinguish the lesion muscle Primitive or neurogenic. For the diagnosis of nerve root compression, EMG has a unique value. It can be seen that the self-generating position and the nerve conduction velocity are normal.

3, muscle biopsy can be seen neurogenic muscle atrophy.

4, head, neck MRI can be normal.

Diagnosis and diagnosis of motor neuron disease

Diagnosis can be based on medical history, clinical symptoms, and laboratory tests.

Differential diagnosis

1, cervical spondylosis: upper limb or shoulder pain, and staged segmental sensory disturbance, no medullary paralysis, imaging examination and sternocleidomastoid EMG are not involved to identify.

2, syringomyelia: the disease is characterized by segmental, separation pain and temperature sensation; according to segmental separation of sensory dysfunction, cervical spinal cord magnetic resonance (MRI) visible cavity.

3, spinal cord tumors and brainstem tumors: different degrees of conduction beam-type sensory disturbances, lumbar puncture, spinal canal obstruction, spinal angiography, CT or magnetic resonance imaging (MRI) showed intra-osseous space-occupying lesions.

4, myasthenia gravis: the same myasthenia gravis easily affects the medulla and limb muscles, but the myasthenia gravis has volatility and other fatigue, it is generally not difficult to identify.

5, multifocal motor neuropathy: clinically similar to motor neuron disease, the main identification is the EMG shows the effect of nerve conduction velocity, especially the discovery of multifocal punctate myelin sheath disease, in addition to this group of patients in the cerebrospinal fluid anti-GMI The positive rate of antibody increase is higher, and sometimes it takes a long time to follow up before identification can be made.

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