It’s a nerve injury which affects upper limbs with functional impairments. It’s caused due to traction force exerted on the upper limb, resulting in complete or partial motor paralysis and sensory sometimes. The areas involved are:

• Upper brachial plexus lesion involves spinal nerves C5 and C6 and leads to paralysis of the shoulder muscles and biceps.
• The damage extends to spinal nerve C7, some of the wrist muscles are also impaired.
• A lower brachial plexus lesion involves spinal nerves C8 and T1 and involve paralysis of the forearm flexor and the intrinsic muscles of the hand.

Causes

1. Motorcycle Accidents: Due to upper limb nerve injury or spinal cord injury.
2. Contact sports: Many players experience burners, which can occur when the nerves in the brachial plexus get stretched beyond their limit during collisions with other players.
3. Birth injury: New-born can sustain brachial plexus injuries. These may be due to high birth weight, breech presentation or prolonged labour. The upper nerves are injured, it’s called Erb's palsy.
4. Trauma: Several types of trauma like including motor vehicle accidents, falls or bullet wounds, etc.
5. Tumours and cancer treatments:  Tumours can grow in or along the brachial plexus, or put pressure on the brachial plexus. Radiation treatments to the chest may cause damage to the brachial plexus.

Complications :

• Stiff joints
• Weak muscles
• Muscle atrophy
• Altered sensations
• Restricted and painful movements of joints
• Disability

Here's how Cura Advanced Physiotherapy will help you with your Brachial Plexus Injury with advanced techniques and planned exercise programs. Our physiotherapy management will include:

• Development of strength, flexibility of muscles
• Maintaining ROM with passive movements, exercise, splinting and positioning and protection of denervated dermatomes. 
• Functional training 
• Pain control
• Reduce oedema with compression garments and massage therapy.

References:

https://pubs.rsna.org/doi/full/10.1148/rg.26si065511

https://apcz.umk.pl/JEHS/article/view/6037

https://www.ausmed.com/cpd/articles/brachial-plexus-injuries