Mononeuropathies (neuritis and neuralgia) are isolated lesions of individual nerve trunks.
The disease is based on direct trauma, compression of the nerve trunk. Predisposing factors are the superficial location of the nerve on the bone or its passage in the channels formed by the bone-ligamentous and muscle elements. In such anatomical conditions, the corresponding parts of the nerve trunks are particularly sensitive to chronic occupational or sports injury, limb compression during deep sleep, etc. (tunnel or trap syndromes). In atherosclerosis, diabetes mellitus, periarteritis nodosa, menoneuropathy is caused by ischemia (ischemic neuropathy). Direct infection of individual nerves is observed very infrequently (characteristic only for leprosy). In a considerable number of cases, the etiology of neuropathy is unknown.
The defeat of the main trunk of the nerve leads to the loss of all its functions. More distal lesions cause only partial damage. The clinical picture depends on the degree of damage to the nerve fibers. The following describes only the syndromes of complete interruption of the main nerves of the limbs in their proximal parts, as well as the clinical course of the most frequent cranial mononeuropathies.
Neuritis of the ulnar nerve, the improbability of flexion of the IV and V fingers of the hand and its deformity according to the type of “clawed paw”;
subsequently, two fingers are in a state of abduction; anesthesia of the ulnar plane of the hand, also IV and V fingers. Most often, the nerve is compressed in the cubital canal at the internal condyle of the humerus.
Neuritis of the radial nerve: improbability of extension in the elbow and wrist joints (“hanging hand”); loss of reflex with m. triceps; anesthesia of the posterior plane of the shoulder, forearm and 1 finger. The nerve is most commonly injured in the shoulder, where it spirals around the humerus.
Neuritis of the median nerve: improbability of pronation of the hand and flexion of the first three fingers; anesthesia of the lateral plane of the palm, I-III fingers and the lateral plane of the IV finger. Most often, the nerve is damaged in the carpal tunnel (the most common carpal tunnel syndrome).
Neuritis of the femoral nerve: improbability of extension in the knee joint; loss of knee jerk; anesthesia of the anterior plane of the thigh and the medial plane of the leg.
Neuritis of the sciatic nerve: improbability of flexion in the knee joint, paralysis of the foot; loss of the Achilles reflex; anesthesia of the lower leg (except for its medial plane) and foot.
Neuritis of the tibial nerea: improbability of plantar flexion of the foot and toes; loss of the Achilles reflex (walking on the fingers is impossible); anesthesia of the plantar plane of the foot. The distal nerve may be compressed in the tarsal canal at the medial malleolus.
Neuritis of the peroneal nerve: improbability of dorsiflexion of the foot (foot sags down and inward); anesthesia of the outer plane of the lower leg and rear of the foot.
The differential diagnosis of mononeuropathies with radicular syndromes and plexus involvement is based on a careful examination of the clinical picture, which is not often difficult to distinguish from radiculopathies (hence the unjustified frequency of diagnosing neuritis of the femoral and sciatic nerves). In favor of discogenic radiculopathies, in particular, the vertebral syndrome (antalgic scoliosis, etc.) testifies, as well as an infrequent increase in protein in the cerebrospinal fluid.
Vasodilators and decongestants, B vitamins, massage, exercise therapy.