ICD-10 Code G56.40 – Causalgia of unspecified upper limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G56.40 – Causalgia of unspecified upper limb
What it is
G56.40 identifies causalgia in an upper limb when the affected side is not specified. It refers to severe, persistent neuropathic pain after nerve injury, and you should use it only when documentation supports that diagnosis.
Clinical signs
Typical findings include burning pain, marked sensitivity to touch, and pain that seems out of proportion to the original injury. Clinical features vary; refer to documentation for nerve involvement and laterality details.
When to use this code
Use this code when the record clearly states causalgia involving an upper extremity but does not identify right or left. It is appropriate for follow-up visits, specialist notes, or problem lists when the diagnosis remains active. If the note only says neuropathic pain, check documentation.
Do not use for
Do not use G56.40 for generalized limb pain, unspecified nerve pain, or conditions that are documented as CRPS without causalgia. If the provider specifies a different nerve disorder or laterality, code that instead.
Coding tip
Confirm the term “causalgia” is documented and avoid assuming laterality when the chart does not state it.