What Is Hereditary Neuropathy?

Hereditary sensory neuropathy is classified as hereditary peripheral neuropathy, which is a group of diseases that are mainly caused by peripheral nerve damage caused by genetic factors. Hereditary sensory neuropathy is mostly inherited, typically manifested as recurrent painless ulcers at the extremities of the limbs due to sensory loss of the skin, and gait instability caused by lack of deep sensory sense. Hand and foot ulcers and secondary osteomyelitis, osteolysis and cellulitis. Dyskinesias are not obvious. It mainly includes: adult disabling hereditary sensory neuropathy; child disabling hereditary sensory neuropathy; and three subtypes of congenital analgesia. Because hereditary sensory neuropathy often has severe autonomic nerve involvement, the above three subtypes and familial autonomic dysfunction are collectively referred to as hereditary sensory autonomic neuropathy.

Causes of hereditary sensory neuropathy

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

Clinical manifestations of hereditary sensory neuropathy

1. Disabling hereditary sensory neuropathy in adults

It is an autosomal dominant inheritance. It begins on the age of 10 to 20 years, mainly involves the feet, and begins to form plantar plantar ridges. Later, blister, ulcer, lymphangitis and irritating pain appear. Distal pain and temperature sensation are absent, touch pressure is relatively mild, and often accompanied by no or little sweat. Most patients have no pain, and a few can have acupuncture pain in the lower limbs or shoulders. The tendon reflexes mostly disappear or decrease, and the muscle strength is generally normal. A few patients may have weakness in the fibula and anterior tibialis muscles, with sagging feet and cross-threshold gait. Occasionally, mild arched feet. Electrophysiological examination showed a decrease in sensory nerve conduction velocity or failure to elicit it.

2. Disabling hereditary sensory neuropathy in children

Early onset in infants or children, delayed toddlers, often with arched feet and ataxia. Repeated infections of ulcers on the toes and fingers cause paronychia and toe (or finger) cephalitis. All kinds of sensations are involved. The pressure sensation is more obvious than the pain and temperature sensation, which mainly affects the distal extremities, and sometimes also affects the trunk. The tendon reflex disappeared, and the limb muscle strength was more normal.

3. Congenital analgesia

This disease is very rare. It is an autosomal recessive inheritance. The gene defect is located at 1q, which is close to the CMT1B gene locus, which encodes a nerve growth factor receptor protein. Generalized analgesia, anhidrosis, and orthostatic hypotension. Body temperature can fluctuate with changes in ambient temperature. Another type of congenital apathy is that patients have the ability to distinguish acupuncture and can distinguish harmful stimuli from harmless stimuli, but have no response to painful stimuli, show indifference, and have no organic changes in the nervous system.

4. Familial autonomic dysfunction

The child was born with sucking difficulties, high fever without obvious incentives, and recurrent pneumonia. On examination, obvious pain and temperature dysfunction can be seen, while the touch pressure sensation is relatively light, tendon reflex disappears, and the dyskinesia is light. Later, clinical manifestations of autonomic dysfunction gradually appear, such as fixed pupils, less tears, corneal ulcers, excessive sweating, transient white spots, cold hands and feet, orthostatic hypotension, abnormal body temperature fluctuations, difficulty swallowing, esophagus and Small intestine dilation and so on. Children may also have mental retardation and mental retardation. About a quarter of patients die around the age of 20.

Hereditary sensory neuropathy

Blood test

Including blood glucose, liver function, kidney function, erythrocyte sedimentation, rheumatism series, immunoglobulin electrophoresis and other autoimmune-related serological tests; serum heavy metal (lead, mercury, arsenic, thallium, etc.) concentration detection; meaningful for differential diagnosis. Decreased serum dopamine hydroxylase is often used as an important biochemical indicator in the diagnosis of this disease.

2. Analysis of genetic defects.

3. Other inspections

(1) Most of the EMG examinations are normal, and some patients show that the sensory nerve conduction speed becomes slower, and the lower limbs are more obvious.

(2) X-ray examination can find toe bone, metatarsal bone destruction, osteolysis or hyperplasia, thickening of periosteum.

(3) The muscle biopsy is normal or denervated, the horizontal stripes disappear, scattered degenerated muscle fibers, and peripheral nerve biopsy. It is found that the small myelinated fibers almost completely disappear and the myelinated fibers are demyelinated.

Diagnosis of hereditary sensory neuropathy

The diagnosis is mainly based on the clinical manifestations of the characteristics, including family genetic history, genetic defect analysis, peripheral sensory nerve electrophysiological examination, and peripheral nerve biopsy, which can help determine the diagnosis.

Differential diagnosis of hereditary sensory neuropathy

Syringomyelia

Most of them are isolated sensory disorders on one or both sides of the upper limbs. They are distributed in the same or half-jersey-like distribution, showing pain and temperature disturbances and normal tactile and deep sensations. The affected limbs may have muscle atrophy, dry and sweatless skin, brittle nails, and autonomic dysfunctions such as Charcoal joints, which are different from the sensory disorders of the disease, and are easy to identify.

2. Leprosy

There are typical skin lesions, hypertrophy of peripheral nerves (ulnar, radial, large auricular nerves, etc.), pain and temperature sensation of the damaged skin, irregularities in severely damaged areas, and positive leprosy can be distinguished from this disease.

3. Amyloidosis

It has digestive symptoms such as diarrhea and constipation; autonomic symptoms such as impotence, abnormal sweating and orthostatic hypotension; abnormalities in the toes and lower limbs, and disturbances in sensation, pain and temperature. Rectal mucosa and peripheral nerve biopsy with amyloid deposits in the tissue can be distinguished from this disease.

Hereditary sensory neuropathy complications

Due to sensory disturbances, it can lead to indifference to external environmental damage factors, which can lead to trauma (scalds, burns, scratches, etc.). Autonomic dysfunction may also occur such as pupil fixation, corneal ulcers, difficulty swallowing, esophagus and small intestine dilation. Children may also have mental retardation and mental retardation.

Hereditary sensory neuropathy treatment

There is no special treatment method, mainly symptomatic treatment, such as avoiding nociceptive injury, strengthening nutrition, regulating cardiovascular function, and promoting gastrointestinal motility. For peripheral nerve damage, neurotrophic drugs such as vitamin B1, vitamin B12, vitamin E, citicoline, adenosine triphosphate (ATP), coenzyme A, etc., as well as drugs such as nerve growth factors, or drugs that can promote nerve function improve. Topical treatment of ulcers caused by this disease. Can also cooperate with acupuncture, physical therapy and other treatments.

Hereditary sensory neuropathy prognosis

Careful patients can also survive to 30 to 40 years of age. Although it is a genetic disease, it is quite rare. Most children die of pneumonia or other complications.