Ulnar neuropathy is a lesion of N. ulnaris, different in etiology, accompanied by a violation of its sensory and motor functions. It is manifested by weakness when trying to squeeze the hand into a fist and hold objects with the brush, lack of sensitivity of the skin of the V and partially IV fingers, atrophy of the hypotenor and small muscles of the hand, the appearance of the hand similar to a clawed paw. In the diagnosis of ulnar neuropathy, they rely on the results of neurological examination, electrophysiological testing, radiography of bones and joints. Therapeutic tactics are built taking into account the genesis of neuropathy and can include both medical and physiotherapeutic methods, as well as surgical treatment.
General information
Ulnar neuropathy is a fairly common lesion of the peripheral nervous system. It often accompanies injuries of the elbow joint, and therefore occurs not only in the practice of neurologists, but also specialists in the field of traumatology.
The anatomical location of the ulnar nerve is such that the most vulnerable place is its site, localized in the area of the elbow joint in the so-called cubital (ulnar) canal. The symptom complex of compression of the ulnar nerve in this channel is called cubital canal syndrome in neurology. Among all neuropathies of compression genesis, it occupies the second place (the first belongs to carpal tunnel syndrome — one of the variants of neuropathy of the median nerve).
Anatomy of the ulnar nerve
The nerve originates in the medial bundle (C7-C8, Th1) of the brachial plexus. Without giving up branches, it passes along the inner side of the shoulder, then passes to its posterior-medial surface. In the area of the elbow joint, it runs along the back surface of the inner condyle of the shoulder, where it is actually subcutaneously. Then it enters the cubital canal formed by the ulnar process, the internal condyle, ligament and tendons of the forearm muscles.
From the elbow to the wrist, N. ulnaris runs along the medial edge of the inner surface of the forearm. Here he gives motor branches to the medial portion of the flexor muscle of the fingers and the elbow flexor of the wrist. At the head of the ulna, the nerve gives the dorsal branch, innervating the skin of the ulnar side of the back of the hand, the back surface of the V, IV and partially III fingers. Passing to the palm, N. ulnaris is divided into superficial and deep branches. The first is responsible for the sensory perception of the skin of the little finger and the half of the ring finger facing it. The second is for the innervation of the hypotenor muscles and small muscles of the hand, as well as joints, ligaments and bones of the hand. After departing from the ulnar nerve, a deep branch passes through the Guyon canal, located between the pea-shaped bone and the metacarpal palmar ligament.
Causes
The most common mechanisms of development of ulnar neuropathy are traumatic nerve damage and its compression in the cubital canal. Nerve injury may be accompanied by: bruising of the arm, dislocation of the forearm, supracondylar fracture of the shoulder, fracture of the medial condyle of the shoulder, fracture of the forearm, isolated fracture of the ulna or fracture of the ulnar process, dislocation of the hand. Cubital canal syndrome often occurs in people who are used to doing elbow support. For example, to lean with your elbow on a desk, a machine, a side of a door in a car, etc.
Compression of the nerve in the ulnar canal and in the Guyon canal is possible with inflammatory or anatomical changes in the structures forming these channels. Thus, compression neuropathy of the ulnar nerve can be observed in osteoma, sprains, synovitis, tendovaginitis, deforming osteoarthritis, rheumatoid arthritis, osteodystrophy, bursitis of the elbow joint, post-traumatic osteoarthritis of the wrist joint and other diseases. Work associated with prolonged pressure of tools (screwdrivers, hammers, scissors, forceps, etc.) on this area can provoke ulnar neuropathy at the level of the Guyon canal.
Symptoms
The lesion of N. ulnaris at the level of the cubital canal is characterized by weakness in the hand, manifested when trying to take something in the hand (for example, pick up a kettle from the stove), play the piano, type on the keyboard, etc. Sensory disturbances are manifested by a feeling of numbness of the little finger, partially ring finger and the elbow edge of the palm. A typical feeling of discomfort in the area of the elbow joint, often pain in it, radiating into the hand along the elbow edge of the forearm. Often, an increase in these symptoms is noted in the morning, which is due to the habit of many patients to sleep with their hands under the pillow or under their head, which means bending them at the elbow joints.
During the examination, attention is drawn to the hypotrophy of the hypotenor and small muscles of the palm, the position of the fingers in the form of a clawed paw (the main phalanges are in the extension position, and the middle ones are bent).
Ulnar neuropathy in the Guyon canal has similar manifestations. The difference is the localization of pain syndrome only in the area of the base of the hand and the hypotenor, the presence of sensory disorders exclusively on the palmar surface of the little finger and half of the ring finger with complete preservation of the sensitivity of the back of the hand.
Diagnostics
During the study, the neurologist reveals hypesthesia of the V and the adjacent half of the IV fingers; incomplete flexion of the V, IV and partly III fingers when trying to assemble the fingers into a fist; the presence of trigger points in the medial condyle of the shoulder, along the radial nerve or in the area of the pea bone. To assess the volume of movements in the patient’s hand, they are asked to put the hand with the palm on the table and, trying to keep it pressed against the table, try to “scratch” the table with the little finger, spread and close the fingers. Difficulty in performing these movements, as well as previous symptoms, indicates ulnar neuropathy.
Electromyography and electroneurography help to clarify the topic of the radial nerve lesion. Ultrasound of the nerve allows to establish the etiology of pathological changes underlying neuropathy and the degree of compression of the nerve in the channels. The analysis of the condition of joints and bone structures is carried out according to the results of radiography of the elbow joint, radiography of the forearm and wrist joint, if necessary, CT of the joints is performed.
N. ulnaris neuropathy should be differentiated from neuropathies of the median and radial nerve, from polyneuropathy of various genesis, from radiculopathy caused by damage to the lower cervical spine in osteochondrosis, myelopathy, spondyloarthrosis, and other pathologies.
Treatment
Therapeutic tactics in relation to ulnar neuropathy largely depends on the etiology of nerve damage. Surgical treatment is required to remove tumors, hematomas, scars that compress the nerve trunk or cause compression of the musculoskeletal canal in which it passes. Surgical tactics are also used in the absence of the proper effect of conservative treatment. According to the indications, nerve decompression, neurolysis, release from adhesions, nerve transposition, removal of a nerve tumor, and other operations are performed.
Conservative therapy involves the appointment of anti-inflammatory drugs (glucocorticoids, diclofenac, ketorolac), painkillers (sodium metamizole, injections of local anesthetics), anticholinesterase drugs (ipidacrine, neostigmine, etc.), vasoactive drugs (nicotinic acid, pentoxifylline), metabolites (vitamins g. B, alpha-lipoic acid). Effectively complements the medical treatment of physiotherapy: UHF, phonophoresis, magnetotherapy. The fight against muscular atrophy is carried out with the help of massage and electromyostimulation.
In the acute period of ulnar neuropathy, an important point is the exclusion / limitation of static and dynamic load, which enhances the pathological manifestations of the disease. Patients suffering from cubital canal syndrome, in order to limit the flexion of the arm at the elbow for the period of night sleep, it is recommended to bandage a towel rolled into a roller to the flexor surface of the elbow. Subsequently, when the inflammatory process subsides and the pain syndrome decreases, a special exercise therapy complex is prescribed.
