Diagnosis of Brachial Plexus Nerve Injury
The clinical diagnosis of brachial plexus nerve requires a thorough examination of every joint, every nerve, and every muscle of the affected limb to arrive at a correct judgment, followed by the following comprehensive clinical analysis. Again, the principles of nerve injury diagnosis are strictly followed!
1, the presence or absence of brachial plexus nerve injury One of the following conditions should be considered the presence of brachial plexus nerve injury.
1, the upper extremity of the five major nerves (axillary, musculocutaneous, median, radial, ulnar nerve), there are any two groups of joint injury (not the same plane of cutting injury)
2.Any one of the three major nerves of the hand (median, radial and ulnar nerves) combined with shoulder or elbow joint dysfunction (normal passive movement)
3.Any of the three major nerves in the hand (median, radial and ulnar nerves) combined with a medial forearm cutaneous nerve injury (non-cutting injury).
2.Determine the site of brachial plexus injury
1, purpose: to facilitate the selection of surgical incision and approach.
2.Method: Clinical examination of the function of the pectoralis major clavicularis representing C5 and C6 nerve roots, the pectoral rib representing C8 and T1 nerve roots, and the latissimus dorsi representing C7 nerve roots.
When the clavicular region of the pectoralis major muscle is normally present (examination method: 45 degrees of forward flexion at the shoulder joint and resistance inversion of the upper arm), it means that the lateral anterior thoracic nerve emanating from the beginning of the lateral bundle of the brachial plexus is functioning well, and the site of brachial plexus injury should be below the lateral bundle (i.e., the lower clavicle). Atrophy of the clavicular portion of the pectoralis major muscle suggests superior trunk or C5, C6 radicular injury.
When the thoracic rib portion of the pectoralis major muscle is normally present (examination method: external booth at the shoulder joint, upper arm for resistance to internal retraction), it indicates that the medial anterior thoracic nerve emanating from the beginning of the medial bundle of the brachial plexus is functioning well, and the site of brachial plexus injury should be below the medial bundle (i.e., the lower clavicle).
When the latissimus dorsi muscle is normally present (examination method: external booth at the shoulder joint, upper arm for resistance internal retraction, the examiner taps the area below the inferior angle of the scapula with the hand to see if there is muscle contraction activity. The muscle contraction above the inferior scapula is often interfered with by the inversion of the vastus lateralis), then the thoracic dorsal nerve from the middle posterior fasciculus is functioning well. Atrophy of the latissimus dorsi muscle suggests injury to the middle trunk or injury to the C7 nerve root.
3, localization and diagnosis of the trunk branch of the brachial plexus nerve
In the preoperative localization of brachial plexus injury, in addition to distinguishing the upper and lower clavicle injury, should further clarify the root or stem injury on the clavicle, as well as the inferior clavicle bundle or branch injury, the specific method should be the clinical examination of the positive signs obtained, according to the five major nerve classification of the upper extremity after the combination of diagnosis.
(1) Brachial plexus nerve root injury
Theoretically, clinical symptoms and signs can only be seen when two adjacent nerve roots are injured at the same time, and we call this phenomenon single-root compensatory phenomenon and double-root combination phenomenon. For the convenience of description, the brachial plexus nerve roots are divided into the upper and lower brachial plexus. The upper brachial plexus includes C5-7 nerve roots; the lower brachial plexus includes C8 nerve roots and T1 nerve roots.
1, upper brachial plexus nerve injury
Main clinical manifestations.
The shoulder joint cannot be abducted and lifted, the elbow joint cannot be flexed but can be extended, the wrist joint can be flexed and extended but the muscle strength is weakened. The lateral sensation of the upper extremity is largely absent, the thumb sensation is diminished, the 2nd-5th fingers, the hand and the medial forearm sensation are completely normal, and muscle atrophy of the shoulder can be found, mainly in the deltoid muscle, and muscle atrophy of the upper arm, mainly in the biceps. In addition, forearm rotation was also impaired, while finger movement was still normal.
The above symptoms are similar to those of upper brachial plexus (C5, C6) injury, and whether there is a combined C7 injury, it is important to check whether there is paralysis of the latissimus dorsi and the common finger extensor muscles. If there is atrophy of the trapezius muscle, limited shrugging activities, and paralysis of the scapularis and rhomboid muscles, it means that the upper brachial plexus nerve root is broken at the intervertebral foramen or preganglionic avulsion injury.
2.Nerve root injury of lower brachial plexus
Clinical manifestations.
Loss of hand function or serious impairment, shoulder, elbow, wrist joint movement is still good, the affected side often appears Horner’s sign. When examined, it can be found that the internal muscles of the hand are all atrophied, among which the interosseous muscles are the most important, there are claw-shaped hand and flat hand deformity, the fingers can not be flexed or have serious impairment, but the metacarpophalangeal joints exist straightening action (the function of the common finger extension muscle), the thumb can not be palmarly abducted. Skin sensation is absent on the ulnar side of the forearm and hand, and skin sensation on the medial side of the arm may also be absent.
The above symptoms are similar to the injury of the inferior brachial plexus and medial bundle. If Horner’s sign appears, it proves that the T1 sympathetic nerve has been severed, which often indicates the injury of C8 and T1 near the intervertebral foramen or preganglionic injury. The clinical symptoms and signs are similar to those of C8 and T1 nerve root injury alone, but careful examination may reveal paralysis of the latissimus dorsi muscle or loss of muscle strength, as well as loss of muscle strength of the common finger extensor muscle, and the plane of sensory impairment may expand radially.
(2) Brachial plexus nerve trunk injury
1.Supra-brachial plexus nerve trunk injury
C5, C6 nerve joint constitutes the upper trunk of the brachial plexus nerve. When the upper trunk is injured, the axillary nerve, musculocutaneous nerve and suprascapular nerve are paralyzed, and the radial nerve and median nerve are partially paralyzed, and their clinical symptoms and signs are similar to those of upper brachial plexus injury.
2.Brachial plexus nerve trunk injury
The middle trunk of the brachial plexus nerve is composed of the C7 nerve alone, and its independent injury is rarely seen clinically, except for a short period of time (usually 2 weeks) the muscle strength of the extensor group is affected, but there are no obvious clinical symptoms and signs.
3.Inferior trunk injury of brachial plexus nerve
When it is injured, the ulnar nerve, medial root of median nerve, medial brachial cutaneous nerve and medial forearm cutaneous nerve become paralyzed, and the lateral root of median nerve and radial nerve become partially paralyzed. The clinical symptoms and signs are similar to those of lower brachial plexus injury. All hand functions (flexion and extension, abduction and adduction) are lost, and no object can be held or pinched.
(3) Brachial plexus bundle injury.
Lateral bundle injury of the brachial plexus
Medial bundle injury of the brachial plexus
Posterior bundle injury of the brachial plexus nerve
(4) Total brachial plexus nerve injury
In the early stage of total brachial plexus injury, the whole upper limb is slowly paralyzed, and the joints cannot move actively, but the passive movement is normal. Due to the existence of trapezius muscle function, the shrugging motion still exists. The sensation of the upper limb was completely lost except for some areas of the medial arm. The medial skin sensation of the upper arm was distributed by both the medial brachial cutaneous nerve and the intercostal brachial nerve, the latter from the second intercostal nerve, so the medial skin sensation of the arm still existed when the whole brachial plexus was injured. All tendon reflexes of the upper extremity were absent, the temperature was slightly low, the distal extremity was swollen, and Horner’s sign appeared. In the late stage, the muscles of the upper limb atrophy significantly, and the joints are often restricted in passive movement due to joint capsule contracture, especially the shoulder and finger joints are serious.
4.Diagnosis of the five major nerve injuries (the most important diagnosis)
(1) Axillary nerve injury.
Clinical manifestations: atrophy of deltoid muscle and limitation of shoulder joint abduction
Single axillary nerve injury its injury plane below the branch; axillary nerve combined with radial nerve injury, its injury plane in the posterior bundle; axillary nerve combined with myocutaneous nerve injury its injury plane in the upper stem; axillary nerve combined with median nerve injury its injury plane in the root of C5.
(2) Myocutaneous nerve injury.
Clinical manifestations: biceps atrophy, limited flexion of the elbow joint
Myocutaneous nerve injury alone, the plane of injury below the branch; myocutaneous nerve injury combined with axillary nerve injury, the plane of injury in the upper trunk; myocutaneous nerve injury combined with median nerve injury the plane of injury in the lateral bundle; myocutaneous nerve injury combined with radial nerve injury, the plane of injury in the C6 nerve root.
(3) Radial nerve injury.
Clinical manifestations: triceps brachii, brachioradialis and wrist extension, thumb extension, finger extension muscle atrophy and functional limitation
Radial nerve injury alone, the plane of injury is below the branch; radial nerve injury combined with axillary nerve injury, the plane of injury is in the posterior bundle; radial nerve injury combined with musculocutaneous nerve injury, the plane of injury is in the C6 nerve root; radial nerve injury combined with median nerve injury, the plane of injury is in the C8 nerve root.
(4) Median nerve injury.
Clinical manifestations: flexion of the wrist and finger muscles, atrophy and atrophy of the greater interphalangeal muscle, limitation of thumb and finger flexion and thumb to palm function, sensory impairment of the 1st-3rd fingers
Median nerve injury alone, the plane of injury is below the branch; median nerve injury combined with myocutaneous nerve injury, the plane of injury is in the lateral bundle; median nerve injury combined with radial nerve injury, the plane of injury is in the C8 nerve root; median nerve injury combined with ulnar nerve injury, the plane of injury is in the inferior trunk or medial bundle.
(5) Ulnar nerve injury.
Clinical manifestations: atrophy of the ulnar carpal flexor muscle, interosseous muscle, internal hand muscle including interosseous muscle and earthworm muscle, and thumb adductor muscle atrophy, limited finger adduction, limited interphalangeal joint extension, limited hand fine function, and sensory impairment of the 4th-5th finger
Injury of ulnar nerve alone, the plane of injury is below the branch; injury of ulnar nerve combined with median nerve, the plane of injury is in the inferior trunk or medial bundle; injury of ulnar nerve combined with radial nerve, the plane of injury is in the thoracic 1 nerve root.
(6) Differential diagnosis of preganglionic and postganglionic injury in the case of brachial plexus nerve root injury
Brachial plexus nerve root injury is divided into two main categories, one is the preganglionic injury within the foramen; the other is the postganglionic injury outside the foramen. The nature of the postganglionic injury is the same as the general peripheral nerve and should be distinguished as a nerve shock, nerve compression, partial or complete nerve disruption. The distinction is based on the nature of the injury, the date, the degree of major functional loss, and different changes in electromyography and nerve conduction velocity. Treatment depends on the pathology and can be conservative and observational or surgical (including decompression and suturing and grafting). Preganglionic injuries are fractured at the anterior and posterior root filaments in the spinal canal, which not only have no ability to heal on their own but also have no possibility of surgical repair, therefore, once the diagnosis is established, early nerve transposition should be sought, so the differential diagnosis of preganglionic and postganglionic is of greater importance in clinical practice.
The nature of postganglionic injury is the same as that of general peripheral nerve, and should be distinguished as nerve shock, nerve compression, partial nerve dissection injury and complete dissection injury. Brachial plexus nerve root injury (avulsion injury) is the most serious type of brachial plexus nerve injury, also known as preganglionic injury, refers to the filamentous structure of the cervical nerve, which constitutes the brachial plexus nerve, is broken in the spinal cord. Since the filamentous structure does not leave a trace on the surface of the spinal cord after rupture, direct repair is not possible, therefore, once the diagnosis is confirmed, early nerve transposition should be performed.
(1) Historical features: the degree of violence causing preganglionic injury is more serious, often combined with a history of coma, multiple fractures of the neck, shoulder and upper extremity, often appearing persistent severe pain.
(2) Features of physical signs: cervical 5 and 6 radical avulsion injuries, significant atrophy of the trapezius muscle, and severe limitation of shoulder shrugging. In cervical 8 and chest 1 radical avulsion injury, Horner’s sign is usually present.
(3) Electromyography: In preganglionic injury, the sensory nerve conduction velocity (SNAP) was normal and the somatosensory evoked potential (SEP) was absent. In the postganglionic injury, the sensory nerve conduction velocity (SNAP) was reduced or disappeared, and the somatosensory evoked potential (SEP) disappeared.
(4) Special tests:
(1) Histamine reaction: the normal skin is pricked with 1% histamine phosphate: local vasodilatation, edema spots, surrounding skin congestion (triple reaction). Preganglionic injury was positive, while postganglionic injury was negative.
②Nerve axon reflex: Immerse the affected hand in cold water at 5 ℃ for 5-10 min, and then the local blood vessels dilate and the temperature increases. This reflex appears when the sensory nerve axon is intact. Therefore, preganglionic injury was positive and postganglionic injury was negative.
Professor Gu Yudong concluded that the following muscles are important in the diagnosis of brachial plexus nerve injury:
(1) Pectoralis major clavicularis (innervated by the lateral anterior thoracic nerve, representing the cervical 5 and 6 nerve roots, examination: forward flexion at the shoulder joint, 45° position of the upper arm for resistance inward contraction), indicating that the injury is below the lateral bundle (lower clavicle); if atrophy, indicating upper trunk or cervical 5 and 6 root injury.
(ii) Pectoralis major (innervated by the medial thoracic nerve, representing the cervical 8 and thoracic 1 nerve roots, examination: external booth at the shoulder joint, resistance inversion of the upper arm) contraction is present, the injury is below the medial bundle (lower clavicle).
If the contraction is good, the brachial plexus injury is below the posterior fasciculus (inferior clavicle); if atrophy is present, it indicates a midstem injury or cervical 7 nerve root injury.