Neuropathy of the median nerve of the hand

Among the most frequently diagnosed diseases of the peripheral nerves is the neuropathy of the median nerve - one of the three main motor-sensory nerves of the hands, providing their movements and sensitivity from the shoulder to the fingertips.

Without taking into account pathogenetic factors, many continue to call it neuritis, and ICD-10 on the basis of anatomical and topographic features of the disease refers it to mono-neuropathies of the upper extremities with code G56.0-G56.1.

[1], [2], [3]

Epidemiology

The exact statistics of this pathology is unknown. Most epidemiological studies focus on carpal tunnel syndrome, which is the most common syndrome of the peripheral compression of the median nerve with a frequency of diseases - 3.4% of all neuropathies: 5.8% in women and 0.6% in men.

European neurologists note that this syndrome is diagnosed in 14-26% of patients with diabetes; about 2% of cases are recorded during pregnancy, almost 10% of professional drivers, a quarter of painters, 65% of people constantly working with vibrating tools, and 72% of workers involved in manual processing of fish or poultry.

But the syndrome of the round pronator is revealed in almost two-thirds of milkmaids.

[4], [5], [6], [7], [8],

Causes of the neuropathy of the median nerve

In most cases, the causes of neuropathy of the median nerve are the squeezing of some part of the nerve trunk, which in neurology is defined as the compression neuropathy of the median nerve, neurocompression or tunnel syndrome. Compression can be the result of injuries: fractures in the head of the shoulder or the clavicle, dislocations and strong impacts of the shoulder, forearm, elbow or wrist joints. If the blood vessels close to the nerve and the capillaries of its endoneurium are subjected to compression, then the compression-ischemic neuropathy of the median nerve is diagnosed.

In neurology, other types of neuropathy of the medial nerve are distinguished, in particular, degenerative-dystrophic, associated with arthrosis, deforming osteoarthritis or osteitis of the shoulder, elbow or wrist joints.

In the presence of chronic infectious inflammation of the joints of the upper extremities - arthritis, carpal osteoarthritis, rheumatoid or arthritic arthritis, articular rheumatism - neuropathy of the median nerve can also occur. Here, as a trigger for pathology, inflammatory processes localized in the synovial pouch of the joints, in the tendons and ligaments (with stenosing tenosynovitis or tenosynovitis) should be included.

In addition, the lesion of the median nerve can lead to neoplasm of the bones of the shoulder and forearm (osteomas, bony exostoses or osteochondrosis); tumors of the nerve trunk and / or its branches (in the form of neurinomas, schwannomas or neurofibromas), as well as anatomical abnormalities.

So, if a person has a rare anatomical formation in the lower third of the shoulder bone (about 5-7 cm above the middle supracondylum) - the spinous supracondylar process (apophysis), then together with the Struser ligament and the humerus, it can form an additional opening. It can be so narrow that the median nerve  and brachial artery passing through it  can be squeezed, leading to compression-ischemic neuropathy of the median nerve, which in this case is called the syndrome of the supra-apical apophysis or the syndrome of the supracondylar process.

[9], [10], [11], [12], [13], [14], [15]

Risk factors

Experts consider unconditional risk factors for the development of the neuropathy of the nerve, the constant tension of the wrist or elbow joints, long-acting with a bent or unbent wrist, peculiar to some professions. The importance of heredity and history of diabetes mellitus, severe hypothyroidism - myxedema, amyloidosis, myeloma, vasculitis, vitamin B deficiency is also noted.

According to some foreign studies, factors associated with this type of peripheral mononeuropathy include pregnancy, increased body mass index (obesity), and in men - varicose veins in the shoulder and forearm.

The threat of neuritis of the median nerve exists with antitumor chemotherapy, long-term use of sulfonamides, insulin, dimethyl biguanide (antidiabetics), drugs with derivatives of glycolyl urea and barbituric acid, thyroid hormone thyroxine, etc.

[16], [17], [18], [19], [20]

Pathogenesis

The long branch of the brachial plexus that emerges from the brachial knot (plexus brachials) in the axillary region forms the median nerve (nervus medianus) running parallel to the humerus: through the elbow joint along the elbow and radius bones of the forearm, through the carpal canal of the wrist brush and fingers.

Neuropathy develops in cases of compression of the middle trunk of the supraclavicular part of the brachial plexus, its outer fascicle (in the exit zone of the upper nerve pedal from the brachial node) or at the point of the inner nerve of the nerve leaving the inner secondary fascicle. And its pathogenesis consists in blocking the conduction of nerve impulses and in violation of the innervation of muscles, which leads to the limitation of the movements of the wrist musculus flexor carpi radialis and the circular pronator (musculus pronator teres) in the region of the forearm-the muscle that provides rotations and rotational movements . The stronger and longer the pressure on the median nerve, the more pronounced nervous dysfunction.

The study of the pathophysiology of chronic compression neuropathies has shown not only segmental, but also often extensive demyelination of the axons of the median nerve in the compression zone, marked puffiness of the surrounding tissues, an increase in the density of fibroblasts in the tissues of the protective nerve shells (perineuria, epineurium), vascular hypertrophy in endoneurium and an increase in the endoneural fluid volume , strengthening squeezing.

There was also an increase in the expression of relaxing smooth muscles of prostaglandin E2 (PgE2); vascular endothelial growth factor (VEGF) in synovial tissues; matrix metalloproteinase II (MMP II) in small arteries; transforming growth factor (TGF-β) in the fibroblasts of the synovial membranes of the joint cavities and ligaments.

[21], [22], [23], [24], [25],

Symptoms of the neuropathy of the median nerve

Basic definitions of diagnoses of compression mononeuropathies: syndrome of the supra-apical apophysis, syndrome of the round pronator and carpal tunnel syndrome or carpal canal syndrome.

In the first case, with the syndrome of the supra-apical apophysis (referred to above), the compression of the median nerve is manifested by motor and sensory symptoms: pain in the lower third of the shoulder (from the inside), numbness and tingling (paresthesia), decreased sensitivity (hypesthesia) and weakening of the muscles of the hand and fingers (parez). The frequency of this syndrome is 0.7-2.5% (according to other data - 0.5-1%).

In the second case, the symptoms of the neuropathy of the median nerve appear after its compression when passing through the structures of the muscles of the forearm (round pronator and flexor of fingers). The first signs of the syndrome of the round pronator include pain in the forearm (giving to the shoulder) and brushes; further note the hypesthesia and paresthesia of the palm and the back surface of the terminal phalanges I, II, III and half of the IV fingers; restriction of rotations and rotational movements (pronation) of the muscles of the forearm and hand, flexion of the hand and fingers. When a disease is started, the innard of the median nerve of the tenar muscle (elevation of the thumb) partially atrophies.

In carpal tunnel syndrome, compression of the median nerve trunk occurs in a narrow bone-fibrous carpal tunnel (carpal canal) through which, along with several tendons, the nerve extends into the wrist. With this pathology, the same paresthesia (not passing through at night) is noted; pains (down to intolerable - causalgic) in the forearm, hand, the first three fingers and partly the index finger; reduction of muscle motility of the hand and fingers.

Soft tissues in the area of the clamped nerve in the first stage swell, and the skin reddens and becomes hot to the touch. Then the skin of the hands and fingers pale or acquire a cyanotic shade, become dry, and the horny layer of the epithelium begins to slough. Gradually there is a loss of tactile sensitivity with the development of asteroognosis.

In this case, the symptomatology, which manifests the neuropathy of the right median nerve, is identical to the signs that arise when the squeezing is localized on the left arm, that is, there is a neuropathy of the left median nerve. For more details see -  Symptoms of the defeat of the median nerve and its branches

Complications and consequences

The most unpleasant consequences and complications of neuropathic syndromes of the medial nerve of the upper limbs are atrophy and paralysis of peripheral muscles due to a violation of their innervation.

In this case, the motor limitations relate to the rotational movements of the brush and its flexion (including the little finger, ring finger and middle finger) and compression into the fist. Also, due to the atrophy of the muscles of the thumb and little finger, the brush configuration changes, which prevents small motor skills.

Especially negatively on the condition of the muscles affects atrophic processes, if the compression or inflammation of the nervus medianus led to extensive demyelination of its axons - with the inability to restore the conduct of nerve impulses. Then begins fibrous degeneration of muscle fibers, which after 10-12 months becomes irreversible.

[26], [27], [28], [29], [30]

Diagnostics of the neuropathy of the median nerve

Diagnosis of the neuropathy of the median nerve begins with the elucidation of the patient's anamnesis, examination of the limb and evaluation of the degree of nerve damage - on the basis of the presence of tendon reflexes, which are checked with special mechanical tests (flexion-extension of the hand and finger joints).

To find out the cause of the disease, you may need blood tests: general and biochemical, glucose levels, thyroid hormones, CRP content, autoantibodies (IgM, IgG, IgA), etc.

Instrumental diagnostics with the help of electromyography (EMG) and electroneuroraphy (ENG) makes it possible to evaluate the electrical activity of the muscles of the shoulder, forearm and hand and the degree of conduction of nerve impulses by the median nerve and its branches. Also use radiography and myelography with contrast material, ultrasound of vessels, ultrasound, CT or MRI of bones, joints and muscles of the upper extremities.

[31], [32]

Differential diagnosis

Differential diagnosis is intended to distinguish the mononeuropathy of the median nerve from the neuropathy of the ulnar or radial nerve, the defeat of the brachial plexus, the radicular dysfunction in radiculopathy, the scalenus syndrome, the inflammation of the ligament (tenosynovitis) of the thumb, the stenosing tenosynovitis of the finger flexors, the polyneuritis in systemic lupus erythematosus , Raynaud's syndrome, sensitive Jackson epilepsy and other pathologies, in the clinical picture of which there are similar symptoms.

Treatment of the neuropathy of the median nerve

Complex treatment of the neuropathy of the median nerve should begin with minimizing the compression effect and relieving pain, for which the hand is given a physiological position and fixed with a long or orthosis. The cessation of intense pain is carried out by perineural or paraneural neocaine  blockade. While the limb is immobilized, the patient is given a hospital with a neuropathy of the median nerve.

It should be borne in mind that the treatment of the emerging neuropathy does not cancel the therapy of the diseases that caused it.

To reduce pain, medicines can be prescribed in tablets:  gabapentin  (other trade names - Gabagama, Gabalept, Gabantin, Lamitril, Neurontin); Maxigan  or  Deksalgin  (Dexallin), etc.

To relieve inflammation and swelling, resort to paraneural injections of corticosteroids (hydrocortisone).

To stimulate the conduct of nerve impulses, Ipidacrine (Amiridin, Neuromidine) is used. Inside take 10-20 mg twice a day (for a month); injected parenterally (SC or in / m - 1 ml of 0.5-1.5% solution once a day). The drug is contraindicated in epilepsy, heart rhythm disturbances, bronchial asthma, exacerbations of stomach ulcers, pregnancy and lactation; not applicable to children. Side effects include headache, allergic skin reactions, hyperhidrosis, nausea, increased heart rate, the appearance of bronchial spasm and seizures.

Improvement of blood circulation in small vessels and blood supply to tissues is facilitated by Pentoxifylline (Vasonitis, Trental). The standard dosage is 2-4 tablets up to three times a day. There are side effects in the form of dizziness, headache, nausea, diarrhea, increased heart rate, lower blood pressure. Contraindications include bleeding and retinal hemorrhages, liver and / or kidney failure, gastrointestinal ulcers, pregnancy.

To increase the content of high-energy compounds (macrog) in muscle tissues are used preparations of alpha-lipoic acid - Alpha-lipon (Espa-lipon): first drop IV introduction - 0.6-0.9 g per day, after two or three weeks take pills - 0.2 g three times a day. Side effects can be expressed by the appearance of urticaria, dizziness, increased sweating, pain in the abdominal cavity, a violation of the intestine.

With neuropathy associated with diabetes, appoint Carbamazepine (Carbalex, Finlepsin). And all patients need to take vitamins C, B1, B6, B12.

Physiotherapy treatment of neuropathies is very effective; therefore, physiotherapy sessions with ultraphonophoresis (with novocaine and GCS) and electrophoresis (with Dibasol or Prozerin) are mandatory; UHF, pulsed alternating current (darsonvalization) and low-frequency magnetic field (magnetotherapy); usual medical massage and point (reflexotherapy); electrostimulation of muscles with impaired innervation; balneo- and peloidotherapy.

After removing the acute pain syndrome, approximately one week after the immobilization of the hand, all patients are prescribed exercise therapy with neuropathy of the median nerve - to strengthen the muscles of the shoulder, forearm, hand and fingers and increase the range of their flexion and pronation.

Alternative treatment

Of the funds that recommend alternative treatment for this pathology, anesthetic compresses with blue clay, turpentine, a mixture of camphor alcohol with salt, alcohol tincture of calendula. The effectiveness of such treatment, as well as herbal treatment (ingestion from the roots of elecampane or burdock inside) was not evaluated by anyone. But it is precisely known that it is useful to take evening primrose oil (evening primrose), since it contains a lot of fatty alpha-lipoic acid.

[33], [34], [35]

Surgery

If all attempts to cure the compression-ischemic neuropathy of the median nerve by conservative methods are unsuccessful, and motor-sensory disorders do not go away after one to six months, surgical treatment is performed.

In this case, if neuropathy has occurred after trauma due to the intersection of the nervus medianus, the operation to restore its integrity, i.e., stitching or plastic, is done earlier - in order to avoid a persistent limitation of the amplitude of brush movements (contractures).

In carpal tunnel syndrome, surgical decompression of the median nerve (dissecting the carpal ligament) or its release (neurolysis) with the removal of compressive fibrous tissues is performed. Intervention can be performed by open access and endoscopically.

Contraindications to the operation with syndrome of the carpal canal are advanced age, duration of symptoms more than 10 months, constant paresthesia, stenosing tenosynovitis of the flexor.

But the syndrome suprakondilyarnogo (nadnamyshlkovogo) appendage is subject only to surgical treatment: for the purpose of decompression, an operation is performed to remove this bone outgrowth.

Prevention

There is no specially developed method for the prevention of neuropathies.

Diseases of the peripheral nerves, including neuropathy of the median nerve, in many cases can not be avoided. And what is possible? To try not to injure limbs, in time to treat inflammations of their joints, to take vitamins of group B, not to gain extra pounds ...

And if your work is associated with prolonged exertion of the elbow or wrist joint, then you need to take short breaks and perform simple but effective exercises for the joints of the hands: they are described in detail (with illustrations) in the material -  Carpal tunnel syndrome

[36], [37], [38], [39],

Forecast

The probability of complete cure and recovery of movements and sensitivity of the upper limbs, that is, the forecast of the neuropathy of the median nerve, depends on many factors, primarily on the cause of nerve function and the degree of damage to its trunk and membranes.

[40], [41]