Brachial Plexus Injury, It's Types.

 Brachial Plexus Injury 

• Traction injury

• Penetrating wounds

• Stab wounds or gunshot wounds

• Vehicular accidents

• Birth injuries

• Fracture dislocation of the scapula, clavicle or upper part of the humerus

• Shoulder girdle neuritis

• An unusually large cervical rib

• Malignancy of the cervical lymph nodes

• Congenital abnormality of the cervical spine like the Klippel Fail syndrome

• Apical lung tumors.

Types

Brachial plexus injury is classified mainly based upon the site of injury as preganglionic, postganglionic and total plexus injury.

• Preganglionic injury is caused due to avulsion of the roots from the spinal cord. This type of lesion produces both sensory and motor loss. As in preganglionic lesion the dorsal root ganglion is separated from the spinal cord; wallerian degeneration doesn’t take place in the sensory axon even though the patient has peripheral anesthesia. Axon reflex remains intact in the initial stage of the injury. Conduction velocity of the sensory axon remains intact but that of the motor axon remains lost. The prognosis of this type of injury is very poor.

• Postganglionic lesions are the one in which the lesion is distal to the dorsal root ganglion. There is sensory and motor loss. The axon reflex is also lost. Conduction velocity of both the sensory axon and motor axon is affected. As the dorsal root ganglion is not in contact with the remaining portion of the axon, wallerian degeneration is a must and hence such type of injury has a good prognosis.

• Total plexus injury is the one in which the lesion is very close to the vertebral column. This type of brachial plexus injury is very rare. All the muscles supplied by the brachial plexus are paralyzed and even the cervical sympathetic is involved. However if the plexus is involved at the level of the trunk then certain muscles like the rhomboids, serratus anterior, spinalis and pectorals may be spared. Appreciation of touch, pain, thermal sensation is lost over the hand, forearm and the lower third of the upper arm. Joint position sensitivity is lost in the fingers. Tendon reflexes in the upper limb are lost.