What Is Peripheral Nerve Damage?

Peripheral nerve damage is mainly caused by sensory disturbances, dyskinesias, and nutritional disorders in areas dominated by this nerve for various reasons. Peripheral nerves are nerves other than the central nerves (brain and spinal cord). It includes 12 pairs of brain nerves, 31 pairs of spinal nerves and vegetative nerves (sympathetic, parasympathetic).

Basic Information

English name: peripheral nerve injury
Visiting department: neurosurgery
Common causes: Stretch injury, cutting injury, compression injury, firearm injury, ischemic injury, etc.

Common symptoms: Drooping of upper limbs, atrophy of small hand muscles, deltoid muscle atrophy (square shoulder), ape palm deformity, etc.

Causes of peripheral nerve injury

The causes of peripheral nerve injury can be divided into: traumatic injuries such as brachial plexus injuries caused by birth injuries; cutting injuries such as knife cuts, chainsaw injuries, glass cuts, etc .; compression injuries such as fracture dislocations, etc. Nerve compression; Firearm injuries such as gunshot and shrapnel injuries; Ischemic injuries; Ischemic contractures of the limbs and nerve damage; Electrical and radiation burns; Drug injection injuries and other iatrogenic injuries.

Clinical manifestations of peripheral nerve injury

Brachial plexus injury

Mainly manifested as motor and sensory disorders in the nerve root type distribution area. The upper brachial plexus injury manifested as drooping of the entire upper limb, adduction of the upper arm, no abduction and outward rotation, straightening of the forearm adduction, no pronation, supination, or flexion. There was a long and narrow sensory impairment area on the outside of the scapula, upper arm and forearm. The lower part of the brachial plexus is manifested as atrophy of all the small muscles of the hand and a claw shape. There is a sensory loss in the ulnar side of the hand and the inner side of the forearm, and Horner syndrome sometimes occurs.

Axillary nerve injury

Mainly manifested as dyskinesia, reduced shoulder abduction, and sensory impairment of the skin in the deltoid region. The deltoid muscles atrophy, the shoulders lose the appearance of round bulges, and the acromion peaks protrude, forming a "square shoulder".

3. Myocutaneous nerve injury

After the musculocutaneous nerve emanates from the lateral bundle, it crosses the coracalis brachialis obliquely, descends between the biceps brachii and the brachialis muscle, and issues a branch to dominate the above three muscles. The terminal branch is slightly outside the elbow joint, penetrates the deep fascia of the arm, and is renamed the lateral cutaneous nerve of the forearm, which is distributed on the outer skin of the forearm. Skin dysfunction of the biceps brachii, brachialis and lateral forearm after musculocutaneous nerve injury.

4. Median nerve injury

Loss of flexion of the first, second, and third fingers; loss of thumb-to-palm movement; atrophy of the great intermuscular muscles, malformation of the ape palm; loss of sensation in the index and middle fingers.

5 Radial nerve injury

Radial nerve injury is the most susceptible to damage to the nerves throughout the body, and is often complicated by fractures of the middle humerus. The main manifestation is the disappearance of wrist extension, and "vertical wrist" is a typical condition; the abduction of the thumb and the extensor muscles disappear;

6. Ulnar nerve injury

The distal segment of the fourth and fifth fingers cannot be flexed; the interosseous muscles are paralyzed, and the abduction and abduction function of the fingers is lost; the atrophy of the little fish is flattened; the feeling of the little finger disappears completely.

7. Femoral nerve injury

Dyskinesias, paralysis of the anterior femoral muscles, difficulty in raising legs while walking, and inability to extend the calf. Sensory disorders, skin dysfunction in front of the thighs and inside of the calf. Quadriceps atrophy and sacrum protruding. The knee reflex disappeared.

8. Sciatic Nerve Injury

When the sciatic nerve is completely injured, the clinical manifestations are similar to those when the tibiofibular nerve is injured. The ankle and toe joints do not move autonomously, and the foot sags to form a horseshoe-like deformity. The ankle can move in a swinging manner with the movement of the affected limb. Calf muscle atrophy, Achilles tendon reflex disappeared, knee flexion was weak, and knee extension was normal. Calf skin sensations, except for the medial side, are often manifested as reduced sensation due to compression of the cutaneous nerve. When the sciatic nerve is partially injured, the biceps femoris is often paralyzed, and the semitendinosus and hemimenis muscles are rarely affected. In addition, calf or sole of the foot is often accompanied by jumping pain, tingling or burning.

9. Common peroneal nerve injury

Dyspepsia is deformed. In order to prevent the toes from being dragged to the ground, the foot is held high while walking, showing a gait;

Peripheral nerve injury examination

Injury examination

Check for wounds, and if there is a wound, check its extent and depth, soft tissue damage, and infection. Find out the path of gunshot wound or shrapnel injury, whether there is vascular injury, fracture or dislocation. If the wound has healed, observe the condition of the scar and the presence of aneurysm or arteriovenous fistula.

2. Limb posture

Observe the limbs for deformities. Radial nerve injuries include carpal ptosis; ulnar nerve injuries include claw-shaped hands, that is, metacarpophalangeal joints of the fourth and fifth fingers are overextended, and interphalangeal joints are flexed; median nerve injuries include ape hands; common peroneal nerve injuries include foot droop. If the time is too long, due to the loss of balance against the muscles, joint contracture and other changes can occur.

3. Examination of motor function

According to the state of muscle paralysis, the nerve damage and its degree are judged, and the muscle strength is distinguished by the six-stage method. No muscle contraction at level 0 ; Muscle contraction at level 1 ; Level 2 does not oppose the direction of gravity and can achieve full joint motion; Level 3 opposes the direction of gravity; it can reach full motion of the joint, but no resistance can be added; Level 4 can resist the direction of gravity and add a certain resistance to achieve full joint motion; Level 5 is normal.

Peripheral nerve injury causes muscle paralysis, loss of tension, and progressive muscle atrophy. According to the degree of nerve injury, muscle strength has the above-mentioned differences. During the nerve recovery process, muscle atrophy gradually disappears. If you persist in exercise, you can make continuous progress.

4. Examination of sensory function

Examine pain, touch, temperature, two points of difference and their range of change to determine the degree of nerve damage. Generally check the pain and touch. Note that the sensory supply area is a single nerve or other nerve supply overlap, which can be compared with healthy skin. Physical sensations and shallow sensations are fine sensations, and pain and deep sensations are coarse sensations. After nerve repair, rough sensation recovers better earlier.

Six levels of sensory dysfunction can also be used to distinguish the degree: level 0 is completely no sensation; level 1 deep pain exists; level 2 has pain and partial touch; level 3 pain and touch are complete; level 4 pain and touch are complete, and there are two points Distinguish, but the distance is large; Level 5 feels completely normal.

5. Nutrition changes

After nerve injury, the skin in the innervation zone became cold, sweatless, smooth, and atrophic. Sciatic nerve injuries often involve plantar pressure ulcers and frostbite. Non-sweating or less sweating areas generally correspond to the disappearance of sensation. A sweat test can be made.

6. Reflection

Depending on muscle paralysis, tendon reflexes disappear or diminish.

7. Pseudoneuroma at the proximal stump of the nerve

There is often severe pain and tenderness, and the tenderness spreads to this innervation zone.

8. Neural dry tap test (Tinel sign)

When the nerve is injured or the injured nerve is repaired, at the level of the injury or the site where nerve growth reaches, the palatine nerve is light, that is, the radioactive paralysis of the nerve distribution area occurs, which is called a positive Tinel sign.

9. Electrophysiological examination

EMG and evoked potentials were used to determine the extent and extent of nerve injury, recovery after anastomosis, and prognosis.

Diagnosis of peripheral nerve injury

According to the history of trauma, clinical symptoms and examinations, the location, nature and extent of nerve injury were judged.

Peripheral nerve injury treatment

Non-surgical therapy

For peripheral nerve injury, whether or not surgery, the following measures should be taken to maintain limb circulation, joint mobility and muscle tension, to prevent deformities and trauma. Paralyzed limbs are susceptible to trauma, frostbite, burns, and crushing, and care should be taken to protect them.

2. Surgical treatment

In principle, the sooner the nerve is repaired, the better. Sharp wounds should be repaired in the first stage. Firearm wounds should not be repaired in the early stage of debridement. Second stage repair will be performed 3 to 4 weeks after the wound is healed. If the sharp injury is not repaired in the early stage, it should also be repaired in the second stage. The period of secondary repair is preferably 3 to 4 weeks after wound healing. The main surgical treatment methods are neurolysis and nerve anastomosis.

3. Nerve transfer and transplantation

Nerve transfer is used for hand trauma, which can use nerve transfer of residual fingers to repair other nerves that damage fingers. In the upper limbs, the superficial branch of the radial nerve can be used to repair the distal sensory nerve or superficial branch of the ulnar nerve. In brachial plexus root injury, phrenic nerve transfer can be used to repair musculocutaneous nerve, cervical plexus motor branch transfer to repair axillary nerve or superior scapular nerve. Autotransplantation is preferred for nerve transplantation. Commonly used nerves for transplantation are the sural nerve, saphenous nerve, medial forearm cutaneous nerve, lateral femoral cutaneous nerve, and superficial branch of radial nerve.

4. Muscle Transfer

When nerve injuries cannot be repaired, muscle transfer is performed to rebuild function. If the radial nerve injury cannot be repaired, the flexor muscles can be transferred instead of the extensor thumb, total extensor and wrist muscles. When the ulnar nerve cannot be repaired, the superficial flexor muscle can be used instead of the interosseous and vermiform muscles. When the muscle branch cannot be repaired, the superficial flexor flexor, ulnar wrist extensor, or little finger abductor can be used to replace the thumb-palm muscle. When the musculocutaneous nerve cannot be repaired, part of the latissimus dorsi or pectoralis major muscle can be used instead of the brachii Biceps and so on.

5. Postoperative management

Post-flexion of the joint is fixed with plaster, so that the anastomotic nerve is not subject to any tension. Usually 4 to 6 weeks after surgery, remove the plaster, gradually straighten the joints, practice joint activities, massage related muscles, and promote functional recovery. But straighten the joints too quickly to avoid breaking the anastomosis. Care should also be taken to protect the affected limb from trauma, burns and frostbite. The flexed knee anastomoses the sciatic nerve; postoperatively, knee flexion and hip extension are fixed with plaster.