Peripheral nerve injury: symptoms, treatment

According to various authors, trauma to peripheral nerves accounts for 1.5 to 3.5% of the total number of injuries in peacetime, and in terms of loss of ability to work, it ranks among the first and often leads to severe disability of patients in almost 65% of cases.

Surgery of injuries and diseases of the peripheral nervous system as a section of restorative neurosurgery is acquiring extremely important significance in our time, first of all, in connection with the growth of traumatism, including domestic, road traffic, and gunshot injuries to nerves, with an increase in the number of lesions of peripheral nerves, combined, and iatrogenic injuries. At the same time, many patients with injuries and diseases of the peripheral nervous system do not always receive timely and qualified medical care, which leads to their persistent disability (according to various data, in 28-75% of cases). The overwhelming majority of such patients are young people of working age.

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What causes peripheral nerve injury?

Nerve trauma in the upper limbs occurs in the lower third of the forearm and hand (almost 55% of all upper limb injuries), with about 20% of them accompanied by damage to several nerves. Injuries in the axillary region and upper third of the shoulder, accounting for only 6% of all injuries, are quite often (almost half of the cases) accompanied by damage to two or more nerves. For the lower limb, the risk zone is the lower third of the thigh - upper third of the shin, which accounts for almost 65% of all peripheral nerve injuries.

There is still no generally accepted unified classification of peripheral nerve injuries. The vast majority of classifications of peripheral nerve trunk injuries differ significantly in both form and content from classification schemes of other injuries, such as those of the musculoskeletal system.

Nature of peripheral nerve injury:

• household;
• production;
• combat;
• transport;
• iatrogenic.

Symptoms of Nerve Injury

During a neurological examination, symptoms characteristic of a nerve injury are revealed:

• Sensory disturbances (from anesthesia in the corresponding innervation zone with complete damage to the nerve trunk, to hypoesthesia or paresthesia with partial damage).

Scheme for assessing sensory impairment:

1. S0 - anesthesia in the autonomous innervation zone;
2. S1 - vague pain sensations;
3. S2 - hyperpathy;
4. S3 - hypoesthesia with decreased hyperpathy;
5. S4 - moderate hypoesthesia without hyperpathia;
6. S5 normal pain sensitivity

• Disturbances in muscle strength (in the form of development of peripheral paresis and paralysis according to the innervation of a given nerve).

Muscle strength assessment scheme

1. M0 - absence of muscle contractions (paralysis);
2. M1 - weak muscle contractions without convincing signs of joint movement;
3. M2 - movements under the condition of eliminating the weight of the limb;
4. МЗ - movements with overcoming the weight of the limb;
5. M4 - movements with overcoming a certain resistance;
6. M5 - complete clinical recovery.

• Disturbances in the trophism of muscles and skin in the area of the damaged nerve.

In some cases, when peripheral nerves are injured, a pain syndrome is determined (pain in the nerve trunk itself with irradiation to the zone of its innervation, the presence of Tinel's symptom - shooting pain with irradiation along the nerve trunk when tapping at the site of injury, and sometimes the development of complex pain syndromes such as amputation pain syndrome or complex regional pain syndrome type 2 with the development of causalgia). Quite often, partial damage to nerves, especially the median and tibial portion of the sciatic nerve, is accompanied by pain syndrome.

Among the peripheral nerve injuries, a special group in terms of severity, clinical features and treatment is occupied by injuries to the brachial plexus. They are most often caused by traction of the nerve trunks, for example, when falling from a motorcycle, with dislocations in the shoulder joint, etc. One of the first descriptions of the clinical picture of brachial plexus injury belongs to I. I. Pirogov in "The Principles of Military Field Surgery" (1866), Duchenn (1872) described injury to the upper primary trunk of the brachial plexus, and Erb (1874) described this type of injury in more detail and, based on the clinical and electrophysiological studies, came to the conclusion that the most common site of rupture in such cases is the area at the junction of the C5-C6 spinal nerves (Erb's point). For damage to the brachial plexus according to the Duchenne-Erb type (mainly dysfunction of the suprascapular, axillary, musculocutaneous and partially radial nerves), the most characteristic symptoms are paresis or paralysis of the muscles of the shoulder girdle and shoulder with relatively preserved function of the muscles of the forearm and hand and impaired sensitivity in the innervation zone of C5-C6.

Symptoms of damage to the lower trunk were described by Dejerine-Klumpke (1885), who was the first to note that Horner's syndrome is associated with damage to the first thoracic spinal nerve or its sympathetic branches. Unlike the upper type, damage to the brachial plexus of the Dejerine-Klumpke type (mainly dysfunction of the ulnar and median nerves) is characterized by paresis and paralysis of the muscles in the distal parts of the limb (forearm, hand) and sensitivity disorders in the innervation zone of C7, C8-Th1.

In addition to these classic types, there is a total version of damage to the brachial plexus.

There are several levels of damage to the brachial plexus:

• Level I - preganglionic damage to the brachial plexus roots;
• Level II - damage to spinal nerves:
  • with pronounced retrograde changes up to the anterior horns of the spinal cord;
  • with minor retrograde changes;
• Level III - damage to the trunks, bundles or long branches of the brachial plexus.

Diagnosis of peripheral nerve injury

The diagnosis of nerve injury is made on the basis of a comprehensive examination, including: patient complaints, anamnesis with mandatory clarification of the circumstances of the injury, a thorough examination of the patient and the site of injury (the probability of damage to the nerve trunk is assessed taking into account the location of the injury), neurological examination and additional research methods.

Among the methods of additional diagnostics of peripheral nerve damage, electrophysiological methods are of leading importance. The most informative methods of studying the function of the neuromuscular apparatus are studies of evoked potentials (EP) of nerves and muscles, electroneuromyography (ENMG), intramuscular electromyography (EMG), registration of somatosensory evoked potentials (SSEP), evoked sympathetic skin potentials (ESSP). To assess the motor function of the nerve, such indicators as the latent period, the amplitude of the M-response (the potential that occurs in the muscle during electrical stimulation of the motor nerve), and the velocity of excitation conduction (VEC). To assess the sensitivity function of peripheral nerves, the method of determining the VEC during antidromic or orthodromic stimulation is used.

Bone X-ray is performed in case of suspected fractures, compression of the nerve by bone callus or metal plate, in the presence of dislocations. In addition, the use of this method is justified to clarify the degree of consolidation of bone fragments, which in most cases determines conservative and surgical tactics.

MRI as a highly informative method of examination is used only in some diagnostically complex cases of lesions of the brachial and lumbosacral plexuses, sciatic nerve and in the process of differential diagnostics with lesions of the spine and other brain. For diagnostics, MRI has exceptional informativeness in comparison with other methods, since it allows visualizing directly the spinal roots, identifying traumatic meningoceles formed as a result of the detachment of the roots from the spinal cord, the degree of expression of the atrophic process of the spinal cord, and also to assess the condition of the muscles that are innervated by individual nerves or plexuses as a whole.

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Treatment of peripheral nerve injury

Provision of assistance to victims with peripheral nerve injuries is provided in stages. At the stage of emergency medical care for patients with peripheral nerve injuries, the standard of care organization is urgent transportation of the victim to a medical institution (to trauma centers, trauma, surgical departments, polytrauma departments). The optimal solution for isolated injuries of peripheral nerves is hospitalization of the patient immediately to a specialized microsurgical or neurosurgical department.

The main activities that should be carried out at the stage of emergency medical care:

1. Inspection and assessment of the nature and extent of damage, including associated damage.
2. Assessment of the general condition of the victim.
3. Stopping bleeding.
4. Immobilization of the injured limb(s).
5. If indicated, administer painkillers, carry out anti-shock and resuscitation measures.

If difficulties arise with performing a neurological examination, peripheral nerve injury should be suspected if there are: damage to the main vessels, motorcycle injury (brachial plexus injury), fractures of the pelvic bones and clavicle.

It is not advisable to perform neurosurgical interventions on peripheral nerves in non-specialized medical institutions. At this stage, it is necessary to exclude concomitant lesions; establish a preliminary diagnosis; carry out resuscitation and anti-shock measures; prevent the development of infectious complications (perform primary surgical treatment, prescribe antibacterial therapy); perform an intervention to finally stop bleeding and immobilize fractures; in case of closed injuries of peripheral nerves and plexuses, prescribe restorative treatment and ensure regular (at least once every 2-4 years) electroneuromyographic monitoring of the quality of restoration of the function of the neuromuscular apparatus.

Patients without respiratory failure and with stable hemodynamics must be transported to specialized neurosurgical hospitals. In specialized microsurgical or neurosurgical hospitals, a detailed assessment of the neurological condition should be performed, the neurological level of damage to the peripheral nerve and/or plexuses should be determined, ENMG should be performed to assess the degree of loss of function and a detailed determination of the level of closed damage. After the examination, a diagnosis should be established that would reflect the nature, type and level of damage, the type and localization of concomitant lesions, neurological symptoms, complications.

Surgical treatment of peripheral nerve injuries should be performed as quickly as the patient's condition allows. To avoid technical errors at the stage of surgical treatment of traumatic injuries of peripheral nerves, a number of conditions must be present, without which surgical intervention on nerve trunks is contraindicated (the presence of a specialist who has the skills of microsurgical technique with perfect knowledge of the topographic anatomy of peripheral nerves, capable of providing accurate diagnostics of the nature, degree and level of nerve damage; the presence of microsurgical equipment, instruments, suture material, equipment for intraoperative electrodes on gnostics).

In case of open damage to peripheral nerves, the optimal method is to suture the nerve during primary surgical treatment (PST), if the above-mentioned conditions exist. If these conditions are not met, the surgical intervention should be performed as soon as possible (preferably within two weeks or, in extreme cases, within the first month after the injury).

In case of closed injuries, it is advisable to refer patients early to specialized medical institutions, conduct intensive conservative restorative treatment and constant dynamic monitoring with mandatory ENMG control. In case of absence of signs of restoration of nerve function within 4-6 weeks or in case of ineffective restoration against the background of intensive therapy within 3-6 months (depending on the clinical picture and ENMG data), surgical intervention in a specialized department is recommended.

In isolated injuries of peripheral nerves and plexuses, as a rule, there are no difficulties in making a diagnosis and the quality of care provided to patients depends entirely on determining the optimal treatment tactics and its technical support. Compliance with the basic conditions when providing care to patients with nerve injuries allows us to resolve the issue of surgical treatment in the optimal time frame - the first 14 days (or even the first 12 hours) for open injuries and 1-3 months for closed injuries of peripheral nerves. In this case, the most adequate care should be considered in specialized microsurgical and neurosurgical departments.

In case of combined damage to peripheral nerves, the quality of care provided to the patient depends on the type of damage and the severity of the patient's condition. In case of closed bone fractures and dislocations with simultaneous damage to the peripheral nerve, the following are indicated:

1. In case of closed reposition (reduction) - rehabilitation therapy, observation and ENMG in dynamics. In case of absence of signs of restoration of nerve function (ineffective restoration) with intensive rehabilitation treatment, surgical intervention in a specialized department is indicated within 1-3 months (depending on the clinical picture and ENMG data).
2. In case of open reposition (reduction) - revision of the nerve during the operation with subsequent tactics depending on the surgical findings. In case of tendon and nerve damage, one-stage reconstructive surgery should be considered optimal in order to restore the integrity of the specified anatomical structures. In case of nerve and vascular damage, one-stage reconstructive surgery is also desirable.

Such patients should be taken to specialized departments and operated on as quickly as possible, primarily to restore normal blood circulation to the limb. The question of intervention on peripheral nerves in this case should be decided depending on the complexity of the surgical intervention, its duration and the somatic condition of the patient.

A difficult group of patients with combined injuries of the peripheral nerves, first of all, in terms of diagnosis, are patients who need emergency medical care for vital indications. These are victims who, along with injuries to the plexuses and individual nerve trunks, have injuries to the skull and brain, internal organs, main blood vessels, multiple bone fractures. They need resuscitation both at the scene of the event and during evacuation. In this case, the importance of timely transportation of such victims to specialized medical institutions in accordance with the localization of the dominant injury is of great importance. And the initial period of treatment for patients in this group is mainly resuscitation. The accompanying injury of the plexuses and individual nerve trunks usually attracts little attention from doctors and is therefore often not diagnosed. However, even a diagnosed nerve injury cannot be operated on due to the severity of the patient's condition. The optimal solution is to hospitalize such patients in polytrauma departments or hospitals under the supervision of experienced specialists of various qualifications, including neurosurgeons.

Another complex group of victims are patients with iatrogenic lesions of peripheral nerves. Considering that most of these patients require urgent specialized care due to the possibility of irreversible changes in the nerve trunks, along with preventive measures and mandatory neurological alertness of medical personnel, it is advisable to send these patients to specialized neurosurgical institutions as soon as possible.

Contraindications to neurosurgical intervention for damage to peripheral nerves:

• shock, respiratory and cardiovascular disorders;
• development of infectious complications at the site of injury or proposed surgical access.
• lack of conditions for performing surgical interventions on peripheral nerves,

Absolute indications for neurosurgical intervention are:

• open injuries of peripheral nerves with complete impairment of function;
• closed injuries resulting from bone fractures, if open reposition is performed (it is necessary to revise the corresponding nerve trunk);
• injection injuries of peripheral nerves with aggressive drugs (calcium chloride, cordiamine);
• progressive decrease in the function of the nerve trunk in the case of increasing edema, compression or hematoma.

Relative indications for neurosurgical intervention are:

• damage to peripheral nerves, which is accompanied by partial loss of their function;
• injection injuries of peripheral nerves with non-aggressive drugs;
• iatrogenic closed injuries of peripheral nerves;
• traction and other closed traumatic injuries of peripheral nerves;
• damage to peripheral nerves, which are accompanied by their significant defect (mainly for the purpose of performing reconstructive orthopedic interventions);
• peripheral nerve injuries due to electrical trauma.

Surgeries for nerve injuries

The main requirement for surgical access is the ability to sufficiently view the nerve at the level of damage in the proximal and distal directions. This allows free manipulation of the nerve trunk, correct assessment of the nature and size of the damage and subsequent sufficient intervention. Surgical access should be as atraumatic as possible and performed in compliance with the patterns of the location of the lines of force and Langer's line. It should not be performed directly above the projection line of the nerve trunk, so that coarse scars do not form subsequently, which, in addition to a cosmetic defect, entails secondary compression of the nerve trunk.

When a nerve trunk is compressed, neurolysis is performed (excision of tissues causing compression of the nerve or its fibers). When the anatomical integrity of the nerve is compromised, it is necessary to suture it. In this case, it is possible to suture it by the epineurium (epineural suture), by the epineurium with the capture of the perineurium (epineural suture), or to suture individual nerve fibers (fascicular suture).

If it is impossible to match the ends of the damaged nerve by mobilization, displacement to another anatomical bed, etc., autoplasty is performed (a section of another nerve trunk is sutured between the ends of the damaged nerve. In this case, minor donor nerves are used, for example, the sural nerve). If it is impossible to restore the integrity of the damaged nerve trunk, neurotization is used (suturing the distal end of the damaged nerve to the proximal end of another nerve, the function of which can be sacrificed to ensure the functioning of the muscles innervated by the damaged nerve trunk).

The main requirements for both the suture and the other trunk are the most accurate matching of the ends, taking into account the fascicular structure of the nerve and the absence of tension (holding the suture with a 7/0 thread).

A detailed neurological examination after the intervention in patients with nerve injury should be performed at least once every 4 weeks. After completion of neurosurgical treatment, the patient is transferred to the rehabilitation or neurology department.