This is a multi-center prospective observational study that will capture detailed information about the treatment and long term outcomes of 250 patients with PNI resulting from upper extremity trauma. The study will focus on a young adult population to include individuals ages 18-65. Patients with PNI will be recruited during the hospitalization for initial treatment of the upper extremity injury. Additional patients may be identified during clinic visits for on-going treatment of upper extremity injuries as nerve injuries evolve or upon referral from outside physicians. However, all eligible nerve injuries must be treated within 6 months of the initial upper extremity trauma. Outcomes will be assessed at 3, 6, 12, 18 and 24 months following diagnosis of the nerve injury. All assessments will take place in the clinic and will include a patient interview and a brief exam to evaluate sensory and motor function.

Inclusion Criteria:

1. Ages 18-65

2. Sustained a peripheral nerve injury (including iatrogenic injuries and partial nerve injuries) resulting from upper extremity trauma meeting the following criteria:

   1. Involves injury or dysfunction to motor, or motor and sensory function of the axillary, radial, median, ulnar, or musculocutaneous nerve with injury localized distal to the brachial plexus cord level and proximal to the distal flexion crease of the wrist
   2. Involves a "mixed" nerve segment (i.e. involves a location of any of the above specified nerves that can be expected to have both sensory and motor axons present) but does not include sensory only distal terminations of the same nerves.

3. Receiving surgical treatment (i.e. exploration, neurolysis, repair or reconstruction, nerve or tendon transfer) within 6 months of the initial injury.

Exclusion Criteria:

1. Injuries to the brachial plexus roots, trunks, divisions and cords
2. Injuries to the nerves distal to the distal flexion crease of the wrist
3. Injuries that involve a distal extension of the parent nerve that is considered sensory only (superficial radial nerve, lateral ante brachial cutaneous nerve, etc)
4. Previous motor or sensory deficit prior to injury (e.g. resulting from trauma, stroke, muscular, neurologic, neuromuscular disorder, etc.)
5. Documented psychiatric disorder that limits ability to consent and maintain follow-up
6. Unable to speak either English or Spanish
7. Severe problems with maintaining follow up (e.g patients who are prisoners or homeless at time of injury or who are intellectually challenged without adequate family support).

450 Patients with PNI that meet the eligibility criteria.