BRACHIAL PLEXUS INJURIES AND THEIR TREATMENT

Brachial plexus
The brachial plexus nerve structure formed by the union of branches of the cervical roots C5, C6, C7, C8 and T1. From this union come the nerves that are responsible for movement and sensation in the upper limb. Its injuries are highly debilitating and complex in treatment.
Brachial plexus
 

Brachial plexus injury after falling down fron a motorcycle Brachial plexus injury after falling down fron a motorcycle
The origin of brachial plexus injuries is varied, the most frequent being trauma (motorcycle accidents, particularly), but may also be due to birth trauma ( obstetric brachial plexus injury) or secondary to tumors, treating them with radiotherpy or even after surgery for other reasons. The most common mechanism is sudden traction after violent separation of the shoulder and head (motorcycle falls, for example) or upper limb be pulled up (in case of a fall, for example).
Brachial plexus injury after falling down from a motorcycle
 
Brachial plexus injury during delivery
 
Brachial plexus injury during delivery
 
Types of brachial plexus injury: pre-ganglionic and post-ganglionic
The brachial plexus injuries in relation to the dorsal root ganglion are classified as:
Pre-ganglionic injuries (or root avulsions): it is the uprooting the nerve roots at the point where they leave the spinal cord. They are very serious and irreparable spontaneously. Require surgical treatment to start with. In fact it is best to diagnose them early and avoid unnecessary delays in surgical treatment.

Post-ganglionic injuries: occur after the nerves come out of the spine. They may be complete or a nerve damage in continuity. The first will require surgical repair. The latter may, in some cases, show a more or less partial spontaneous recovery. In turn, these lesions may be located above the collarbone or clavicule (supraclavicular) or below it (infraclavicular). Sometimes in the same patient there are injuries at two levels (nerve root and peripheral nerves) or even at various points at the peripheral level.

Types of brachial plexus injury: pre-ganglionic and post-ganglionic
 
Clinical examination of a patient with a right brachial plexus avulsion of the C5, C6 and C7 roots
The first step will be to establish an accurate diagnosis of the level and severity of the injury/injuries to apply the most appropriate treatment. A thorough physical examination will provide important clues that will be confirmed by studies using MRI and electrophysiology. The latter should be repeated periodically to see the evolution of the injury and if a spontaneous is to be expected (more or less complete) or if surgical repair is essential to achive a useful recovery.
Clinical examination of a patient with a right brachial plexus avulsion of the C5, C6 and C7 roots
 

In the pre-ganglionic avulsion injuries the only treatment is surgery, providing healthy nerve axons that allow to replace, as far as possible, those irreversibly injured. Depending on the lesion, it can be used nearby nerves such as the spinal nerve, the intercostal nerves or C7 root from the other side arm (healthy). There are many technical possibilities and their application always depends on what was injured and what remains healthy in this brachial plexus. As a rule, lesions in higher roots (C5, C6 and C7) are easier to repair and show better results than in the case of injuries of the lower roots (C8 and T1).

In the post-ganglionic lesions there are more options. The first step is the diagnosis of the point or points of injury. During surgery the point of injury is evaluated electrophysiologically, trying to figure out whether the injury is complete or parcial (there are nervous impulses going through it, even if only partially). If the injury is complete or conduciton is poor, the diseased segment is removed and replaced with nerve grafts. These grafts are obtained from other nerves from the patient such as cutaneous sensory nerves, that can be removed without serious consequences (will leave an area of ​​skin least sensitive). When the lesion is large, severe or old, we proceed to take some of the nerve branches from neighboring healthy nerves to innervate the muscles of the damaged one. It is a quick and very effective way to revitalize a denervated area. Typically this works and, if planned well, the deficit is minimal in the healthy nerve from which some branches are subtracted. There are now many nerve transfers, applicable depending to the case and the severity of the injury. The most common are the transfer of spinal nerve branch to the trapezius muscle to the suprascapular nerve, the branch of the long head of the triceps to the axillary nerve, a bundle of the median nerve to the motor branch of the biceps brachii muscle, of a bundle of the ulnar nerve to the motor branch of the brachialis muscle, the two branches of the median nerve at the posterior interosseous nerve and the anterior interosseous nerve to the ulnar nerve.

Right axillary nerve injury: pre-operative situation
Right radial nerve anastomosis to the axillary nerve: outcome one year after surgery
Right axillary nerve injury: pre-operative situation
Right radial nerve anastomosis to the axillary nerve: outcome one year after surgery
Anastomosis of a ulnar nerve fascicle to the motor branch of the biceps brachii muscle (Technique Oberlin I)
Anastomosis of a median nerve motor fascicle to the motor branch of the brachialis anterior muscle (Oberlin Technique II)
Anastomosis of a ulnar nerve fascicle to the motor branch of the biceps brachii muscle (Technique Oberlin I)
Anastomosis of a median nerve motor fascicle to the motor branch of the brachialis anterior muscle (Oberlin Technique II)

In relation to the timing of the repairs, avulsions should be repaired as soon as possible, because there is no possibility of spontaneous recovery. In post-ganglionic lesions weusually wait 2-3 months to see if there is spontaneous recovery. When in doubt it is best to explore the plexus than to keep waiting. Beyond 6 months is better to start thinking in healthy nerve transfers of neighby nerves. After two years there will not be an effective nerve regeneration and it is better to use methods of tendon transfer. With these muscles are transferred or thier insertion point changed trying to alleviate, as far as possible, the loss of function. Are palliative surgeries, but may be useful to increase the functionality of the injured limb.

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