Radial neuropathy is a pathology of N. radialis in any part of it, having a different genesis (metabolic, compression, post-traumatic, ischemic). It is clinically manifested by the symptom of a “hanging hand” due to the inability to straighten the hand and fingers; impaired sensitivity of the posterior surface of the shoulder, forearm and back of the 3.5 first fingers; difficulty in withdrawing the thumb; loss of extensor elbow and carporadial reflexes. It is diagnosed mainly according to neurological examination, auxiliary are: EMG, ENG, radiography and CT. The therapeutic algorithm is determined by the etiology of the lesion, includes etiopathogenetic, metabolic, vascular, rehabilitation therapy.
General information
Radial neuropathy is the most common peripheral mononeuropathy, for its occurrence it is sometimes enough just to put your hand incorrectly during a sound sleep. The development of radiation neuropathy is often secondary and is associated with muscle overloads and injuries, which makes this pathology relevant both for specialists in the field of neurology and for traumatologists, orthopedists, sports doctors. The topic of the lesion of N. radialis is reduced to three main levels: in the area of the armpit, at the level of the middle 1/3 of the shoulder and in the area of the elbow joint. The features of the location of the radial nerve at these levels will be described below.
Anatomy of the radial nerve
The radial nerve originates from the brachial plexus (C5-C8, Th1). Then it passes along the back wall of the armpit, at the lower edge of which it fits snugly to the intersection of the widest muscle of the back and the tendon of the long head of the triceps of the shoulder. At this level, the first place of potential compression of n. radialis is located. Next, the nerve passes in the so—called “spiral groove” – a furrow located on the humerus. This furrow and the heads of the triceps muscle form a brachial (spiral) channel, passing through which the radial nerve wraps around the humerus in a spiral. The brachial canal is the second place of possible nerve damage. After leaving the canal, the radial nerve follows to the outer surface of the elbow joint, where it divides into deep and superficial branches. The elbow area is the third place of increased vulnerability of N. radialis.
The radial nerve and its motor branches innervate the muscles responsible for the extension of the forearm and hand, the withdrawal of the thumb, the extension of the proximal phalanges and the supination of the hand (its palm up). Sensory branches provide sensitive innervation of the capsule of the elbow joint, the posterior surface of the shoulder, the back of the forearm, the back surface of the radial edge of the hand and the first 3.5 fingers (except their distal phalanges).
Causes
The most common radial neuropathy is due to its compression. Often, patients who have compression of n. radialis occurred in a dream due to an incorrect position of the hand turn to a neurologist. Such a “sleep paralysis” can happen in people suffering from alcoholism or drug addiction, in healthy people who have fallen asleep in a state of acute alcohol intoxication, in people who have fallen asleep soundly after hard work or lack of sleep. Compression of the radial nerve with the subsequent development of neuropathy can be caused by the imposition of a tourniquet on the shoulder to stop bleeding, the presence of lipoma or fibroma at the nerve passage site, repeated and prolonged sharp bending in the elbow during running, conducting or manual labor. Compression of the nerve in the armpit is observed when using crutches (so—called “crutch paralysis”), compression at the wrist level – when wearing handcuffs (so-called “prisoner’s paralysis”).
Neuropathy associated with traumatic nerve damage is possible with a fracture of the humerus, injuries to the joints of the arm, dislocation of the forearm, isolated fracture of the head of the radius. Other factors in the development of radiation neuropathy are: bursitis, synovitis and post-traumatic arthrosis of the elbow joint, rheumatoid arthritis, epicondylitis of the elbow joint. In rare cases, the cause of neuropathy is infectious diseases (typhus, influenza, etc.) or intoxication (poisoning with alcohol surrogates, lead, etc.).
Symptoms
The lesion of N. radialis in the armpit manifests a violation of the extension of the forearm, hand and proximal phalanges of the fingers, the inability to move the thumb to the side. A “hanging” or “falling” brush is characteristic — when pulling the arm forward, the brush on the side of the lesion does not take a horizontal position, but hangs down. At the same time, the thumb is pressed against the index finger. Supination of the forearm and hand, flexion at the elbow — weakened. The extensor elbow reflex falls out, the carporadial reflex decreases. Patients complain of some numbness or paresthesia in the area of the back of the I, II and partially III fingers. Neurological examination reveals hypesthesia of the posterior surface of the shoulder, the back of the forearm and the first 3.5 fingers with the preservation of sensory perception of their distal phalanges. Hypotrophy of the posterior muscle group of the shoulder and forearm is possible.
Radial neuropathy at the level of the middle 1/3 of the shoulder (in the spiral channel) differs from the above clinical picture by the preservation of extension in the elbow joint, the presence of an extensor elbow reflex and normal skin sensitivity of the posterior surface of the shoulder.
Radial neuropathy at the level of the lower 1/3 of the shoulder, elbow joint and upper 1/3 of the forearm is often characterized by increased pain and paresthesia on the back of the hand when working with bending the arm at the elbow. Pathological symptoms are observed mainly on the hand. Complete preservation of sensitivity on the forearm is possible.
Radial neuropathy at the wrist level includes 2 main syndromes: Turner syndrome and radial tunnel syndrome. The first is observed with a fracture of the lower end of the beam, the second — with compression of the superficial branch of the n. radialis in the area of the anatomical snuffbox. It is characterized by numbness of the back of the hand and fingers, burning pain on the back of the thumb, which can radiate into the forearm and even the shoulder. The sensory disturbances detected during the examination usually do not go beyond the I finger.
Diagnostics
The fundamental method of diagnosing neuropathy N. radialis is a neurological examination, namely, the study of the sensory sphere and the conduct of special functional tests aimed at assessing the performance and strength of muscles innervated by the radial nerve. During the examination, the neurologist may ask the patient to extend his arms forward and hold the hands in a horizontal position (a hanging hand is detected on the side of the lesion); lower his arms along the trunk and turn the hands palms forward (a violation of supination is detected); withdraw the thumb; having matched the palms of the hands, spread the fingers apart (on the side of the lesion, the fingers bend and slide down the healthy palm).
Functional tests and sensitivity studies make it possible to differentiate radiation neuropathy from ulnar neuropathy and median nerve neuropathy. In some cases, radial nerve neuropathy resembles a CVII-level radiculopathy. It should be borne in mind that the latter is also accompanied by a disorder of flexion of the hand and reduction of the shoulder; characteristic pain of the root type, which increases with sneezing and head movements.
Electromyography, which reveals a decrease in the amplitude of muscle action potentials, and electroneurography, which informs about the slowing down of the nerve impulse along the nerve, allows to establish the topic of the lesion of the radial nerve. An important diagnostic value is the determination of the nature (compression, post-traumatic, ischemic, toxic, etc.) and the causes of neuropathy. For this purpose, it is possible to consult an orthopedist, traumatologist, endocrinologist, radiography of the shoulder, forearm and hand bones, CT of joints, biochemical blood analysis, blood sugar analysis, etc. examinations.
Treatment
The main directions in the treatment of radiation neuropathy are: elimination of etiopathogenetic factors of pathology development, supportive metabolic and vascular therapy of the nerve, restoration of the function and strength of the affected muscles. With any genesis of the disease, radial nerve neuropathy requires a comprehensive approach to treatment.
According to indications, etiopathogenetic therapy may consist of antibiotic therapy, anti-inflammatory (ketorolac, diclofenac, ibuprofen, UHF, magnetotherapy) and decongestant (hydrocortisone, diprospan) treatment, detoxification by drip administration of sodium chloride and glucose solutions, compensation for endocrine disorders, dislocation reduction, bone reposition in case of fracture, application of a fixing bandage, etc. Neuropathy traumatic genesis often requires surgical treatment: the implementation of neurolysis, nerve plasty.
In order to restore the nerve as soon as possible, metabolic (calf blood hemodialysate, vit B1, vit B6, thioctic k-ta) and vasoactive (pentoxifylline, nicotine k-ta) drugs are used. For the rehabilitation of the muscles innervated by him, neostigmine, massage, exercise therapy, and electromyostimulation are prescribed.