Inclusion Criteria:

- Patients with neuropathic pain associated with avulsion injuries following traumatic
brachial plexus injuries scheduled for brachial plexus exploration and reconstruction
by three senior surgeons at Mayo Clinic (AYS, ATB, RJS):

- Neuropathic pain defined as pain directly related to injury to the somatosensory
system, and score >4/10 on the Douleur Neuropathique en 4 Questions (DN4) neuropathic
pain questionnaire. Symptoms of neuropathic pain include allodynia, hyperalgesia,
burning, needle-like, throbbing, shooting, or electrical-type sensation.

- Nerve root avulsion on CT myelogram.

- Traumatic brachial plexus injuries defined as blunt or penetrating trauma resulting in
injury and dysfunction along the course of the brachial plexus defined as nerve roots
C5-T1, trunks, divisions, cords, and terminal branches.

Exclusion Criteria:

- Patients without pain following traumatic brachial plexus injuries.

- Patients with brachial plexus injuries due to non-traumatic causes such as tumors,
infection, radiation, or inflammatory disorders such as Parsonage Turner Syndrome.

- Patients who do not require surgery for exploration/reconstruction at the brachial
plexus.

- Patients under 18 years of age.

- Contraindication to ketamine use (severe hepatic dysfunction -cirrhosis, high-risk
coronary artery disease, poorly controlled psychiatric condition- schizophrenia.

Eligibility last updated 6/21/22. Questions regarding updates should be directed to the study team contact.