Symmetric lower motor neuron paralysis of the extremities

Introduction Lower motor neuron spasm, also known as peripheral sputum. It is the result of damage to the motor fibers of the anterior horn cells (or cranial nerve motor cells), the anterior spinal cord, the peripheral nerves, and the peripheral nerves of the brain. Symptoms of motor neuron spasm in the limbs are caused by motor neuron disease, which is characterized by lower motor neuron symmetry of limbs. Motor neuron disease (MND) is a group of neurodegenerative diseases that are unexplained and selectively damage the anterior horn of the spinal cord and the motor nucleus of the brainstem. The clinical manifestations are the coexistence of upper and lower motor neurons of the limbs, without affecting the sensory system, autonomic nerves, and cerebellar function.

Cause

The etiology and pathogenesis are unclear. 5% to 10% of patients have a family history called familial motor neuron disease. In recent years, genetic abnormalities of superoxide dismutase have been found in this group of patients with family history of motor neuron disease, and it is believed that this may be the cause of the disease. With the application of experimental motor neuron disease model in the active immunization of animals with spinal cord anterior horn cells, autoantibodies have been detected in patients with serum and cerebrospinal fluid anti-GM1 antibodies, increased anti-calcium channel antibody detection rate and immunosuppressive therapy. The theory of the mechanism has received much attention.

an examination

Related inspection

Nervous system examination

Diagnosis is based on clinical manifestations.

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 the disease is hidden and progresses slowly. Clinical symptoms often occur in the distal part of the upper extremity, which is characterized by atrophy and weakness of the hand muscles, and gradually develops in the forward arm, upper arm and scapula; the atrophic muscle has obvious fasciculation; at this time, the lower extremity is the upper motor neuron, which is expressed as Increased muscle tone, hyperreflexia, positive pathology. Symptoms usually develop from one side to the other. Basic symmetry damage. With the development of the disease, symptoms of nucleus dysfunction of the medulla oblongata and pons, and atrophy of the lingual muscles, dysphagia, and speech ambiguity may occur gradually; the late onset muscle strength and respiratory muscles may be affected in the late stage. The main clinical features of ALS: upper and lower motor neurons are simultaneously damaged.

2. Progressive medullary paralysis: The lesion is confined 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 the location of the lesion:

(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 are obvious muscle atrophy and muscle weakness, tendon reflex decline, and muscle fasciculation. Developed to the lower limbs or neck muscles, causing respiratory paralysis. Very few can develop from the far end to the near end.

(2) juvenile type (near-end type): Most of them start from adolescence or childhood, have a family history, and are autosomal recessive or dominant. Clinically, the pelvic girdle and the lower extremity muscle weakness and muscle atrophy, the gait is unstable when walking, the abdomen bulge when standing, and the scapular band and the proximal muscle of the upper limb are weak and muscle atrophy, and there is anterior horn stimulation (muscle beam tremor ), the supine position is not easy to get up.

(3) Infant type: It is an autosomal recessive genetic disease that 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 that develops in the mother has a significant reduction or disappearance of fetal movement, and the child who develops after birth has a weak crying, obvious purpura, systemic flaccid muscle weakness and muscle atrophy. Atrophy begins with the pelvic girdle and the proximal end of the lower extremity, developing toward the scapula, the neck, and the distal extremities. The muscles innervated by the cranial nerves are also extremely vulnerable. However, the muscle bundle is rarely seen in clinical practice. Intelligence, sensation and autonomic function are relatively intact.

3. Progressive muscular atrophy: after the onset of 40 years of age, the symptoms of medullary lesions appear early in the lesion, the patient may have atrophy of the lingual muscles, difficulty swallowing, drinking water cough and language ambiguity. Later, due to damage to the bridge brain and cortical brain stem bundle, it can be combined with the performance of pseudobulbar paralysis, such as invasion of the cortical spinal cord side of the limbs, hyperreflexia and pathological reflex positive.

4. Primary lateral sclerosis: middle-aged men have more morbidity, clinically manifested slowly on the limbs of motor neurons, muscle weakness, increased muscle tone, hyperreflexia and pathological signs. There is usually little muscle atrophy that does not affect sensory and autonomic function. Cortical medullary bundles that can invade the brainstem, manifested as pseudobulbar paralysis.

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

Differential diagnosis

Differential diagnosis of motor neuron spasm in symmetry of limbs:

1, 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.

2, multifocal motor neuropathy: clinically very similar to motor neuron disease, the main identification is the electromyography showed the influence of nerve conduction velocity, especially the multifocal punctate myelin lesions found. In addition, the positive rate of anti-GMI antibody increase in cerebrospinal fluid of this group of patients was higher. Sometimes it takes a long time to follow up to make an identification.

3. Central paralysis of the lower extremities: The central paralysis of the lower extremities is a clinical manifestation of congenital hydrocephalus. When the hydrocephalus is severe and the progress is rapid, it may also appear. The symptom is repeated vomiting. Brain degeneration, brain developmental disorders, central limb spasm, especially lower limbs.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.