Syndromes of brachial plexus lesions

Along with selective damage to individual nerves extending from the brachial plexus, dysfunctions of all or part of this plexus are often observed.

According to the anatomical structure, the following symptom complexes of damage to the primary and secondary bundles of the brachial plexus are distinguished. In the case of a pathological process in the supraclavicular region, the primary bundles are affected.

The syndrome of damage of the upper primary fascicle (CV - CVI) is observed with a pathological focus after passing between the scalene muscles, especially at the site of attachment to the fascia of the subclavian muscle. Projectively, this place is located 2 - 3 cm above the clavicle, approximately a finger's width behind the sternocleidomastoid muscle (Erb's supraclavicular point). In this case, the axillary nerve, the long nerve of the thorax, the anterior thoracic nerves, the subscapular nerve, the dorsal nerve of the scapula, the cutaneous-muscular nerve and part of the radial nerve are simultaneously affected.

In such cases, the upper limb hangs like a whip, the patient cannot actively lift it up, bend it at the elbow joint, abduct and turn it outward, or supinate. The function of the brachioradialis muscle and supinator is impaired (innervated by CV - CVI, the fibers are part of the radial nerve). All movements of the hand and fingers are preserved.

Sensitivity is impaired on the outer side of the shoulder and forearm according to the peripheral type. Pressure on the supraclavicular Erb's point is painful.

After 2-3 weeks from the onset of paralysis, atrophy of the deltoid, supraspinatus and infraspinatus muscles, as well as the shoulder flexor muscles, develops. Deep reflexes disappear - from the biceps brachii and carporadius muscles.

Damage to the upper primary bundle of the brachial plexus is called Duchenne-Erb paralysis. This type of paralysis occurs in trauma (falling on an outstretched upper limb, with prolonged throwing of the arms behind the head during surgery, wearing a backpack, etc.), in newborns during pathological births using delivery techniques, after various infections, with allergic reactions to the introduction of antirabies and other serums.

One of the clinical variants of ischemic damage to the upper trunk of the brachial plexus and its branches is neuralgic amyotrophy of the shoulder girdle (Parsonage-Turner syndrome): initially, increasing pain occurs in the region of the shoulder girdle, upper arm and scapula, and after a few days the intensity of the pain subsides, but deep paralysis of the proximal parts of the arm develops. After 2 weeks, distinct atrophy of the anterior serratus, deltoid, periscapular muscles, and partially of the biceps and triceps brachii muscles is revealed. The strength of the hand muscles does not change. Moderate or mild hypoesthesia in the region of the shoulder girdle and upper arm (CV - CVI).

The syndrome of damage to the middle primary bundle of the brachial plexus (CVII) is characterized by difficulty (or impossibility) in extending the shoulder, hand, and fingers. However, the triceps brachii, extensor pollicis, and abductor pollicis longus are not completely paralyzed, since fibers approach them not only from the CVII segment of the spinal cord, but also from segments CV and CVI. The function of the brachioradialis muscle, innervated by CV and CVI, is preserved. This is an important sign in differentiating damage to the radial nerve and the roots of the brachial plexus. In the case of isolated damage to the spinal root or the primary bundle of the brachial plexus, along with the disorder of the function of the radial nerve, the function of the lateral root of the median nerve is also impaired. Therefore, flexion and abduction of the hand to the radial side, pronation of the forearm, and opposition of the thumb will be impaired.

Sensory disturbances are limited to a narrow strip of hypoesthesia on the dorsal surface of the forearm and the outer surface of the back of the hand. Reflexes from the triceps brachii and metacarpophalangeal muscles disappear.

The syndrome of damage of the primary bundle of the brachial plexus (CVII – TI) is manifested by Dejerine-Klumpke paralysis. The function of the ulnar, cutaneous internal nerves of the shoulder and forearm, part of the median nerve (medial root) is switched off, which is accompanied by paralysis of the hand.

In contrast to combined damage to the median and ulnar nerves, the function of the muscles innervated by the lateral root of the median nerve is preserved.

Extension and abduction of the thumb are also impossible or difficult due to paresis of the short extensor of the thumb and the muscle that abducts the thumb, innervated by the radial nerve, since these muscles receive fibers from neurons located in segments CVIII and TI. The function of the main muscles supplied by the radial nerve is preserved in this syndrome.

Sensitivity in the upper limb is impaired on the inner side of the shoulder, forearm and hand according to the radicular type.

Pain is simultaneously disrupted by the function of the connecting branches that go to the stellate ganglion, then the Claude Bernard-Horner syndrome develops (ptosis, miosis, enophthalmos, dilation of the scleral vessels). When these sympathetic fibers are irritated, the clinical picture is different - dilation of the pupil and eye slit, exophthalmos (Pourfur du Petit syndrome).

When the process develops in the subclavian region, the following syndromes of damage to the secondary bundles of the brachial plexus can form.

Lateral brachial plexus lesion syndrome is characterized by dysfunction of the musculocutaneous nerve and the superior branch of the median nerve.

Posterior brachial plexus syndrome is characterized by the shutdown of the function of the radial and axillary nerves.

The syndrome of damage to the medial cord of the brachial plexus is expressed by a violation of the function of the ulnar nerve, the internal leg of the median nerve, the medial cutaneous nerve of the arm and the medial cutaneous nerve of the forearm.

When the entire brachial plexus is affected (total damage), the function of all the muscles of the upper limb girdle is impaired. In this case, only the ability to "shrug the shoulders" may be preserved due to the function of the trapezius muscle, innervated by the accessory nerve, the posterior branches of the cervical and thoracic spinal nerves. The brachial plexus is affected by gunshot wounds to the supra- and subclavian regions, by a fracture of the clavicle, the 1st rib, by a dislocation of the humerus, its compression by an aneurysm of the subclavian artery, an additional cervical rib, a tumor, etc. Sometimes the plexus is affected as a result of its overstretching when the upper limb is strongly pulled back, when it is placed behind the head, when the head is suddenly turned to the opposite side, or when a birth injury occurs in newborns. Less often, this happens with infections, intoxications, and allergic reactions of the body. Most often, the brachial plexus is affected by spasticity of the anterior and middle scalene muscles due to irritative-reflex manifestations of cervical osteochondrosis - anterior scalene muscle syndrome (Naffziger syndrome).

The clinical picture is dominated by complaints of a feeling of heaviness and pain in the neck, deltoid region, shoulder and along the ulnar edge of the forearm, hand. The pain can be moderate, aching or extremely sharp, up to the sensation of the arm "tearing off". Usually, the pain first appears at night, but soon occurs during the day. It intensifies with a deep breath, turning the head to the healthy side, with sharp movements of the upper limb, especially when abducting it (when shaving, writing, drawing), with vibration (working with jackhammers). Sometimes the pain spreads to the axillary region and chest (with left-sided pain, there is often a suspicion of coronary vascular damage).

Paresthesia (tingling and numbness) appears along the ulnar edge of the hand and forearm, hypalgesia in this area. Weakness of the upper limb, especially in the distal parts, hypotension and hypotrophy of the hypothenar muscles, and partially the thenar muscles are determined. Edema and swelling in the supraclavicular region are possible, sometimes in the form of a tumor (Kovtunovich pseudotumor) due to lymphostasis. Palpation of the anterior scalene muscle is painful. Vegetative-vascular disorders in the upper limb are common, oscillography shows a decrease in the amplitude of arterial oscillations, pallor or cyanoticity, pastosity of tissues, a decrease in skin temperature, brittle nails, osteoporosis of the bones of the hand, etc. are observed. Arterial pressure in the upper limb can change under the influence of tension of the anterior scalene muscle (when abducting the head to the healthy side).

There are several tests to detect this phenomenon: Eaton's test (turning the subject's head toward the sore arm and simultaneously taking a deep breath results in a decrease in blood pressure on that arm; the radial pulse becomes softer); Odeon-Coffey's test (a decrease in the height of the pulse wave and the appearance of a crawling sensation in the upper limbs with a deep breath of the subject in a sitting position with the palms on the knee joints and a slightly straightened head); Tanozzi's test (the subject lies on his back, his head passively tilts slightly and turns to the side opposite to the upper limb on which the pulse is determined; with a positive test, it decreases); Edson's test (a decrease or even disappearance of the pulse wave and a decrease in blood pressure occurs in the subject with a deep breath, raising the chin and turning the head toward the limb on which the pulse is determined).

Scalenus syndrome often develops in people who carry heavy objects on their shoulders (including backpacks, military equipment), as well as in cases of direct muscle injury, osteochondrosis and deforming spondyloarthrosis of the cervical spine, tumors of the spine and spinal cord, tuberculosis of the apex of the lung, and irritation of the phrenic nerve due to pathology of internal organs. Of undoubted importance are the hereditary and constitutional features of both the muscles themselves and the skeleton.

Differential diagnosis of scalenus syndrome must be made with many other painful conditions that are also accompanied by compression and ischemia of the nerve formations of the brachial plexus or irritation of the receptors of the upper limb girdle. X-ray of the cervical spine helps diagnose the syndrome of the additional cervical rib.

Excessive rotation of the shoulder and its outward abduction (for example, in wrestling) can lead to compression of the subclavian vein between the clavicle and the anterior scalene muscle.

Active contraction of the scalene muscles (throwing back and turning the head) leads to a decrease in the pulse wave on the radial artery

The same compression of the vein is possible between the 1st rib and the tendon of the subclavian muscle. In this case, the inner lining of the vessel can be damaged, followed by thrombosis of the vein. Perivascular fibrosis develops. All this constitutes the essence of Paget-Schroetter syndrome. The clinical picture is characterized by edema and cyanosis of the upper limb, pain in it, especially after sudden movements. Venous hypertension is accompanied by spasm of the arterial vessels of the upper limb. Often, scalenus syndrome must be differentiated from pectoralis minor syndrome.

The pectoralis minor syndrome develops when the neurovascular bundle in the armpit is compressed by a pathologically altered pectoralis minor muscle due to neuroosteofibrosis in cervical osteochondrosis. In the literature, it is also referred to as Wright-Mendlovich hyperabduction syndrome.

The pectoralis minor muscle originates from the 2nd to 5th ribs and rises obliquely outward and upward, attaching with a short tendon to the coracoid process of the scapula. With strong abduction of the arm with outward rotation (hyperabduction) and with raising the upper limb high up, the neurovascular bundle is pressed tightly against the taut pectoral muscle and bends over it above the place of attachment to the coracoid process. With frequent repetition of such movements performed with tension, the pectoralis minor muscle is stretched, injured, sclerosed and can compress the trunks of the brachial plexus and the subclavian artery.

The clinical picture is characterized by pain in the chest radiating to the shoulder, forearm and hand, sometimes to the scapular region, paresthesia in the IV-V fingers of the hand.

The following technique has diagnostic value: the arm is taken away and placed behind the head; after 30-40 seconds, pain appears in the chest and shoulder area, paresthesia on the palmar surface of the hand, pallor and swelling of the fingers, weakening of the pulsation in the radial artery. Differential diagnosis must also be made with Steinbrocker's brachial syndrome and brachialgia in diseases of the shoulder joint.

Steinbrocker syndrome, or shoulder-hand syndrome, is characterized by excruciating burning pain in the shoulder and hand, reflex contracture of the muscles of the shoulder and wrist joints with pronounced vegetative-trophic disorders, especially in the hand. The skin on the hand is edematous, smooth, shiny, sometimes erythema appears on the palm or cyanosis of the hand and fingers. Over time, muscle atrophy, flexion contracture of the fingers, osteoporosis of the hand (Sudeck's atrophy) join in and partial ankylosis of the shoulder joint is formed. Steinbrocker syndrome is caused by neurodystrophic disorders in cervical osteochondrosis, myocardial infarction, ischemia of the trophic zones of the spinal cord, as well as in trauma to the upper limb and shoulder girdle.

In brachialgia associated with arthrosis or arthritis of the shoulder joint and surrounding tissues (periarthritis), no symptoms of loss of function of sensory and motor fibers are detected. Hypotrophy of the shoulder muscle is possible due to prolonged sparing of the upper limb. The main diagnostic criteria are limited mobility in the shoulder joint, both during active and passive movements, and data from an X-ray examination of the joint.

Most often, the anterior scalene muscle syndrome has to be differentiated from spondylogenic lesions of the lower cervical roots. The complexity of the problem is that both scalenus syndrome and cervical radiculitis most often have a spondylogenic cause. The scalene muscles are innervated by fibers of the CIII - CVII spinal nerves and, in osteochondrosis of almost all cervical intervertebral discs, are early included in irritative-reflex disorders that occur with pain and spasticity of these muscles. The spastic anterior scalene muscle is stretched when turning the head to the opposite (healthy) side. In such a situation, compression of the subclavian artery between this muscle and the 1st rib increases, which is accompanied by a resumption or a sharp increase in the corresponding clinical manifestations. Turning the head to the side of the affected muscle does not cause these symptoms. If turning the head (with or without load) to the painful side causes paresthesia and pain in the CVI-CVII dermatome, the decisive role of the scalene muscle is excluded. In such cases, paresthesia and pain can be explained by compression of the spinal nerves CVI and CVII near the intervertebral foramen. A test with the introduction of a novocaine solution (10-15 ml) into the anterior scalene muscle is also important. In scalenus syndrome, pain and paresthesia disappear 2-5 minutes after the block, strength in the upper limbs increases, and skin temperature rises. In radicular syndrome, clinical manifestations persist after such a block.

The trunks of the brachial plexus can be compressed not only by the anterior scalene and minor pectoralis, but sometimes also by the omohyoid muscle. The tendinous bridge and its lateral head in the subclavian region are located above the scalene muscles. In such patients, pain in the shoulder and neck area occurs when the upper limb is abducted backward, and the head - in the opposite direction. Pain and paresthesia increase with pressure on the area of the hypertrophied lateral belly of the omohyoid muscle, which corresponds to the area of the middle and anterior scalene muscles.