Hereditary sensory neuropathy

Introduction to hereditary sensory neuropathy Hereditary sensory neuropathy is classified as hereditary peripheral neuropathy, which is a group of diseases caused by genetic factors that are mainly caused by peripheral nerve damage. Hereditary sensory neuropathy is mostly dominant, which is usually caused by loss of skin. Recurrent episodes of painless ulcers at the extremities, gait instability caused by deep sensory loss. Hand and foot ulcers and secondary osteomyelitis, osteolysis and cellulitis, dyskinesia is not obvious. Mainly include: 1 adult disabling hereditary sensory neuropathy (mutilating hereditary sensoryneuropathyinadult); 2 children with disabling hereditary sensory neuropathy (mutilating hereditary sensoryneuropathy in childhood); 3 congenital analgesia (congenitalinsensitivitytopain) three subtypes. Since hereditary sensory neuropathy often has severe autonomic nerve involvement, the above three subtypes and familial dysfunction (familialdysautonomia) are collectively referred to as hereditary sensory autonomic neuropathy. basic knowledge The proportion of illness: 0.0006%-0.0008% Susceptible people: no special people Mode of infection: non-infectious Complications: corneal ulcers dysphagia, mental retardation, mental retardation

Causes of hereditary sensory neuropathy

Cause of disease:

Mostly autosomal dominant inheritance, mostly caused by close relatives marriage. Adult disabling hereditary sensory neuropathy is autosomal dominant. Congenital analgesia is very rare, is autosomal recessive, the gene defect is located at 1q, close to the CMT1B type gene locus, which encodes a nerve growth factor receptor protein. Familial autonomic dysfunction, also known as Riley-Day disease. It is autosomal recessive.

Pathophysiology:

The pathogenesis is still unclear. The main pathological changes are atrophy and thinning of the posterior root and spinal ganglia of the spinal cord, and the spinal nerves of the lumbar spinal cord are obvious. Microscopic examination revealed that the nerve cells in the ganglion were degenerated and disappeared. Myelin sheath and axonal degeneration from nerve ganglia. This change mainly occurs in fine fibers. The spinal cord is atrophied and partially demyelinated. Interstitial structure and Schwann cell proliferation, the anterior horn cells of the spinal cord and the anterior root of the spinal nerve are normal. There is no significant change in skeletal muscle. Cochlear nerves and vestibular ganglia can also atrophy, neuronal degeneration, and reduction. Some patients may have phalanx destruction and humeral bone hyperplasia.

Hereditary sensory neuropathy prevention

Actively do a good job in genetic counseling and publicity of prenatal and postnatal care, carefully investigate their genealogy, early neurophysiological examination and peripheral nerve biopsy for suspected cases. Conduct genetic counseling. Preventive measures include avoiding the marriage of close relatives, genetic testing of carriers, prenatal diagnosis and selective abortion to prevent the birth of the child.

Hereditary sensory neuropathy Complications, corneal ulcer, dysphagia, mental retardation, mental retardation

Due to sensory disturbances, it can lead to disregard of external environmental damage factors, which is easy to cause trauma (scalding, burns, scratches, etc.).

Autonomic dysfunction, such as pupillary fixation, corneal ulcer, dysphagia, esophageal and small intestine expansion, children may also have mental retardation and mental retardation.

Hereditary sensory neuropathy symptoms Common symptoms Feeling inversion, hypotension, reflexes, disappearance, high fever, ataxia, repeated infections

The classification of hereditary sensory neuropathy belongs to hereditary peripheral neuropathy, which can occur from early childhood to adulthood (30-40 years old). The initial symptoms are often ulcers from the foot. Ulcers are painless and intractable and are prone to occur in the weight of the foot and the bottom of the foot. It can be recurrent. If it is a deep penetrating ulcer, it can expose the affected local bones, and periostitis and osteomyelitis can occur in the phalanges, tibia and ribs. This can lead to joints between the toes, pain in the ankle joints, and limited mobility. Some patients may have toe deformation, shortening, and even toe loss. The dorsal artery of the foot is pulsating normally. The range of sensory disturbances is wide. Generally, the lower limbs are heavier than the upper limbs, and often have numbness and ants walking. Sometimes it can show pain in the front and abdomen. The distribution of sensory disturbances in the neurological examination is in the form of gloves and socks. It is important to hurt the pain and temperature. The sense of position and vibration are relatively less damaged. Sometimes it can be expressed as a shallow, deep feeling of dissociative sensory disturbance. Generally no obvious dyskinesia, but there are sputum reflexes. The sputum reflection weakens or disappears. Autonomic dysfunction is generally not obvious, and sometimes there is abnormal sweating in the palms and feet. Cranial nerve involvement often manifests as deafness or optic atrophy, and other cranial nerves are generally unaffected.

According to its genetic form, the age of onset and the difference in sensory impairment, the disease can be divided into four types:

Type I: autosomal dominant genetic disease, which can occur from childhood to adulthood, mainly manifested by sensory loss of the distal extremities, with lower limbs, pain and temperature sensation, __D__?C__ pressure To be severe, there is no sensory ataxia, and some patients may present with tearing pain. Reduced body sweat or no sweat.

Type II: It is an autosomal recessive hereditary disease, which is also known as congenital sensory neuropathy in infants and young children. The main manifestation is the disappearance of various sensations of the skin and skin, with the distal ends of the extremities. There are often paronychia, finger and toe ulcers. Most limbs also have reduced sweat or no sweat.

Type III: a recessive genetic disease in infants and children. The clinical features are infancy, a history of poor feeding, frequent vomiting and pulmonary infection. The child is not sensitive to pain, autonomic dysfunction, including tear secretion defects, poor temperature control, excessive sweating, high blood pressure and orthostatic hypotension. Some children showed slow corneal reflex and disappeared gingival papilla.

Type IV: It is a recessive hereditary sensory neuropathy. It is believed that this disease is caused by abnormal neural crest differentiation. Mainly manifested as insensitive to pain, reduced sweat gland secretion or no sweat. Associated with mental retardation is a feature of this type.

Examination of hereditary sensory neuropathy

1. Blood test: including blood glucose, liver function, kidney function, erythrocyte sedimentation rate, rheumatism series, immunoglobulin electrophoresis and other serological tests related to autoimmunity; serum heavy metal (lead, mercury, arsenic, antimony, etc.) concentration detection; Diagnostic significance, serum dopamine hydroxylase reduction is often an important biochemical indicator for the diagnosis of this disease.

2. Analysis of genetic defects.

3. Most of the EMG examinations are normal, and some patients show that the sensory nerve conduction velocity is slow, and the lower limbs are more obvious.

4. X-ray examination can find the phalanges, destruction of the tibia, osteolysis or hyperplasia, thickening of the periosteum.

5. Muscle biopsy is normal, or denervic changes, transverse stripes disappear, there are scattered degeneration of muscle fibers, peripheral nerve biopsy, found that small unmyelinated fibers almost completely disappear, myelinated fibers demyelinated.

Diagnosis and differentiation of hereditary sensory neuropathy

diagnosis

The diagnosis of this disease mainly depends on the clinical manifestations of the characteristics, family genetic history, gene defect analysis, peripheral sensory electrophysiological examination and peripheral nerve biopsy, which helps to determine the diagnosis.

Differential diagnosis

Should be associated with sensory path destructive lesions caused by loss of sensation or lack of identification, should do a detailed neurological examination, especially the distribution of sensory disturbances, combined with medical history and other clinical features to make the cause of diagnosis.

It is still necessary to distinguish from other hereditary diseases and peripheral neurological diseases according to clinical characteristics. Gene defect analysis, peripheral sensory electrophysiological examination and peripheral nerve biopsy are the main basis for diagnosis.

The disease should be differentiated from the following diseases:

1. Syringomyelia: mostly isolated sensory disturbance of one or both upper limbs. It is distributed like a horse's or semi-horse. It shows pain, temperature is disturbed, and the sense of touch and deep feels normal. The affected limb may have muscle atrophy and dry skin. No sweat, nails become brittle, autonomic dysfunction such as Xia's joints, etc., which is different from the sensory disturbance of this disease and easy to identify.

2. Leprosy: There is typical skin damage, hypertrophy of peripheral nerves (foot, sputum, auricular nerves, etc.), painful feeling of damaged skin, severe temperature perception, irregular area of damage, and difference in the detection of leprosy may be different from this disease. .

3. Amyloidosis: gastrointestinal symptoms such as diarrhea and constipation; autonomic symptoms such as impotence, abnormal sweating and orthostatic hypotension; abnormal sensation of the toes and lower extremities, pain, and temperature sensation, rectal mucosa and peripheral nerves Biopsy, with amyloid deposits in the tissue, can be distinguished from this disease.

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