Peripheral nerve injury are different in the mechanism of damage to the nerve trunks of the peripheral nervous system. They are manifested by pain syndrome and symptoms of a decrease or loss of motor, sensory, autonomic and trophic nerve function distal to the injury site. Peripheral nerve injury is diagnosed based on the results of neurological examination and electrophysiological studies of the neuromuscular apparatus. Treatment can be conservative (painkillers, vitamins, physiotherapy, neostigmine, vasoactive drugs, exercise therapy) and surgical (neurolysis, nerve autoplasty, nerve suture, neurotization).
General information
Injuries of peripheral nerves, according to various data, account for 1-10% of the total number of injuries. Limb wounds are accompanied by damage to nerve trunks in 1.5% of cases, and fractures — in 20% of cases. The areas where nerve injury is most often observed when damaged are the upper third of the shoulder, the armpit, the lower part of the thigh and the upper part of the lower leg. The latter two account for up to 65% of all peripheral nerve trunk injuries.
Every year in the USA up to 7 thousand people need surgical treatment, the indication for which is a peripheral nerve injury. Many patients are discharged from trauma or general surgical clinics with existing neuro-motor deficiency. The lack of timely qualified assistance from specialists in the field of neurology and neurosurgery leads to disability of patients, most of whom are persons of working age. According to some data, persistent disability is observed in 60% of the victims.
Classification
By the nature of the injury, peripheral nerve injury is classified as compression (compression), concussion, contusion (contusion) and anatomical break. The latter can be partial (incomplete), full and intra-barrel. With a partial and intra-trunk break, the possibility of spontaneous regeneration of the nerve remains due to the ingrowth of axons of the terminal sections of its central segment into the peripheral section. The speed of this process is 1 mm per day. Significant nerve damage leads to scar formation and conduction disorder distal to the injury site. A complete anatomical break with the divergence of the ends or the presence of an obstacle between the formed nerve segments in the form of a bone fragment, scar, foreign body causes the development of neurinoma. The outcome of a bruised nerve trunk or hemorrhage into it can also be a neurinoma.
On the other hand, all nerve injuries are divided into open, most often leading to an anatomical break of the nerve, and closed, in which concussion, compression or bruising of the nerve is possible. Open injuries include various wounds: stabbed, torn, cut, chopped, gunshot. In this case, there is a danger of direct infection of the wound tissues. Closed injury of the peripheral nerve is possible with bruising, blunt force trauma, compression of the limb, excessive traction. Closed ones include nerve damage with dislocation and with a closed fracture, its compression with post-traumatic scars, hematoma, callus, etc.
In some cases, combined injuries occur, in which open injury to the nerve is combined with its closed damage. A special group consists of iatrogenic injuries of peripheral nerve trunks that occur as a complication of a number of surgical operations or various medical manipulations.
Injury periods
The acute period takes 3 weeks from the moment of nerve injury. During this period, there is a spread of degenerative changes that occur in the nerve trunk after its injury. Due to certain neurophysiological laws of this process, it is not possible to accurately assess the degree of dysfunction of the injured nerve in the acute period. In this period, surgical treatment is performed for open injuries with visualization of the anatomical break of the nerve while preserving the integrity of the formed segments. In such cases, it is possible to perform a primary nerve suture during the wound PHO in the early stages after injury or to apply a primary delayed suture 2-4 days later.
The early period lasts from 3 weeks to 3 months after the injury and is characterized by the highest regenerative activity of damaged nerve tissues. In the early period, it is possible to accurately determine the degree, type, level and extent of damage; together with a neurosurgeon, solve the issue of therapeutic tactics (conservative or operative) and determine the optimal volume of surgery.
The subacute, or intermediate, period is 3-6 months from injury. There is a significant decrease in the rate of regenerative processes and an increase in the degree of divergence (diastasis) of the ends formed as a result of anatomical nerve interruption. Surgical treatment is possible, but requires the use of complex reconstructive techniques and brings less result.
The late period is from 6 months to 3-5 years after the nerve injury occurred. Due to a significant decrease in the ability to repair and the increase in degenerative changes in the injured nerve trunk, surgical treatment during this period leads to significantly less functional recovery.
The residual, or remote, period is 3-5 years after the damage. Functional restoration of the nerve is not possible. Orthopedic tendon-muscle surgical interventions may be performed to improve the function of the affected limb.
Symptoms
Peripheral nerve injury of any localization is characterized by the presence of several groups of symptoms: motor (motor), sensory (sensory), vegetative (vasomotor and secretory) and trophic.
Motor disorders are characterized by peripheral paresis of muscles that occur immediately after injury, innervated by a section of the damaged nerve located distal to the injury site. Paresis is accompanied by muscle hypotension and hyporeflexia. Over time, they lead to atrophic processes in the muscles. When assessing the paresis zone, the possibility of cross-innervation of some muscle groups should be taken into account.
Sensory disorders are divided into symptoms of irritation (pain, hyperpathy and paresthesia) and symptoms of prolapse (hypesthesia and anesthesia), which are usually combined. Partial damage to the nerve trunk is accompanied mainly by pain and paresthesia. The pain increases with palpation of the nerve trunk below the injury site.
There is a symptom of Tinel — the occurrence of pain shooting along the course of the nerve in the distal direction during pounding in the injury zone. In the case of a complete anatomical break, Tinel’s symptom is negative. The appearance of pain or its intensification in a later period indicates the restoration of sensitivity due to the repair of nerve fibers. At the same time, hyperpathy is most pronounced, often bearing the form of causalgia.
As a rule, in the first days after the injury, the zone of total anesthesia is determined — the absence of all types of sensitivity. Its size and localization may vary due to the individual characteristics of cross-sensory innervation. Usually, a mixed zone with areas of hypesthesia and hyperpathy passes along the edge of the anesthesia area. As the nerve is restored, the area of anesthesia is transformed into the area of hypesthesia, and then (with timely restoration of the integrity of the nerve trunk), sensitivity is normalized.
Vegetative dysfunction manifests itself in the form of anhidrosis of the skin in the area of anesthesia. Approximately in the same area, redness and a rise in local skin temperature are observed, which after 3 weeks is replaced by cooling and pallor. Local pasty tissue is often observed.
Trophic changes develop in a later period. They are characterized by thinning and reduction of skin turgor, its slight vulnerability. There is a striation and clouding of the nails of the injured limb. In the late period, trophic changes may affect the ligaments, tendons and capsule of the joint with the formation of its stiffness, as well as bones with the development of osteoporosis.
Topical symptoms of lesions of various peripheral nerves are described in detail in the articles “Femoral neuropathy“, “Sciatic neuropathy“, “Tibial Neuropathy“, “Fibular Neuropathy“, “Ulnar Neuropathy“, “Radial Neuropathy“, “Median neuropathy“.
Diagnostics
The initial examination of the patient is often carried out by a traumatologist. A peripheral nerve injury is an indication for referring the victim to a neurosurgeon or neurologist. The topic of the lesion is established according to the neurological examination and the results of the EPI of the neuromuscular system. With the help of electroneurography, an increase in the conduction threshold of the nerve trunk can be established. However, experience has shown that these data may not be accurate enough. In this regard, stimulation electromyography is additionally recommended. In the presence of appropriate equipment, the best option is a comprehensive ENMG study that allows you to assess the functional state of both the nerve and the muscles innervated by it.
In order to diagnose damage to the osteoarticular apparatus, radiography of bones and joints is performed, in difficult cases — CT of the bone, ultrasound or MRI of the joint. With the help of these studies, it is also possible to identify compression factors of the nerve trunk.
Treatment
Peripheral nerve injury is not always isolated. With combined injuries and polytrauma, the treatment of life-threatening injuries comes to the fore. After the stabilization of the patient’s condition, they proceed to the treatment of the damaged nerve. It should be carried out by a qualified specialist. If we are talking about surgical treatment, then the operation should be performed by a neurosurgeon in a specialized department with the necessary microsurgical instruments.
Conservative therapy is carried out with closed nerve injuries and in combination with surgical treatment. It is aimed at creating optimal conditions for the speedy regeneration of nerve fibers. In the acute period, immobilization is indicated. Pharmacotherapy is carried out with injectable preparations of vitamins g. B, nicotinic acid with bendazole, neostigmine. If necessary, the treatment regimen includes analgesics and sedatives. From the 4th week, ATP is prescribed. Physiotherapy is widely used: UHF from the 3rd day of injury, electrophoresis, SMT. After 2 weeks, UHF is replaced with diathermy, physical therapy, paraffin applications, massage are recommended. After 1.5-2 months, mud treatment, ozokeritotherapy, hydrotherapy (coniferous, hydrogen sulfide therapeutic baths) are indicated.
The absence of the effect of conservative therapy and open injury of the peripheral nerve with visualization of its interruption are indications for surgical treatment. The optimal timing of the operation is considered to be the first 3 months after the injury. Reconstructive operations on peripheral nerves include: nerve suture, neurolysis, interplastic nerve plasty with an autograft from the external cutaneous nerve of the lower leg. When the nerve is compressed, its decompression of the nerve trunk is performed, if necessary, a new bed is formed. If it is impossible to reconstruct the nerve trunk, neurotization is carried out — the insertion of a less functionally significant nerve trunk into the distal end of the damaged nerve. In the residual period, in order to increase the functionality of the limb, orthopedists can perform tendon-muscle operations.