Injury of accessory nerve, left side, sequela

This code signifies a long-term effect or complication resulting from a previous injury to the left accessory nerve. This nerve, also known as cranial nerve XI, primarily controls the sternocleidomastoid and trapezius muscles, so its injury can lead to chronic weakness, atrophy, or impaired movement of the shoulder and neck on the left side.

Apply this code when documenting a current condition directly attributable to an old injury of the left accessory nerve, where the acute phase of the injury has passed. This includes chronic pain, muscle weakness, or functional limitations in the left shoulder or neck that are a direct consequence of the prior nerve damage. Documentation should clearly state the sequela and its causal link to a past left accessory nerve injury.

• Requires a seventh character "S" for sequela, indicating a late effect.
• Always sequence this code after the code(s) for the specific sequela being treated (e.g., muscle weakness, atrophy).
• Distinguish from acute accessory nerve injuries (S04.72XA, S04.72XD) which are used for initial encounters or subsequent encounters for active treatment.