M43.6 classifies acquired torticollis (wryneck) — a musculoskeletal condition in which involuntary cervical muscle contractions cause the head to tilt to one side and the chin to rotate toward the opposite side. It covers acquired presentations not attributable to a more specific etiology.

Documentation tips

What should appear in the chart to support M43.6.

Source · Editorial brief grounded in 6 cited references ↓

• Specify 'acquired' torticollis in the assessment to distinguish from congenital (Q68.0) and birth-injury (P15.2) presentations — the word 'acquired' supports M43.6 directly.
• Document the absence of spasticity or cervical dystonia features; if spasmodic torticollis is suspected, note any neurological evaluation results, since G24.3 cannot be coded simultaneously with M43.6.
• Record the direction of head tilt and chin rotation, duration of symptoms, and any precipitating events (e.g., pharyngeal infection for Grisel's disease, rheumatic history) to establish medical necessity and etiology.
• For Medicare spinal manipulation claims (98940–98942), document active improvement at each visit and apply the AT modifier — maintenance care is not covered once improvement plateaus.
• If imaging was obtained, document findings (e.g., atlantoaxial rotation, cervical alignment, soft tissue swelling) to support medical necessity and rule out current injury requiring an S-code.

Related CPT procedures

Procedure codes commonly billed with M43.6. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

Common coding pitfalls

The recurring mistakes coders make with M43.6 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

• Coding M43.6 for spasmodic torticollis or cervical dystonia — these require G24.3, which is an Excludes1 condition; simultaneous use of both codes on the same encounter is a compliance violation.
• Using M43.6 for congenital sternomastoid torticollis in pediatric patients — the correct code is Q68.0, not M43.6, regardless of when the patient presents.
• Failing to apply the AT modifier on Medicare spinal manipulation claims (98940–98942) for active torticollis treatment — claims will be denied retroactively.
• Coding M43.6 for torticollis resulting from a current cervical spine injury — acute traumatic presentations must be coded to the appropriate S-code by spinal region and encounter type (A, D, or S).
• Confusing P15.2 (birth injury) with congenital torticollis — birth-injury torticollis in a neonate is P15.2, while structural congenital torticollis is Q68.0; neither maps to M43.6.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

Inclusion & exclusion notes

Per the official ICD-10-CM Tabular List.

Source · CDC ICD-10-CM Official Tabular List · 2026

Sibling codes

Other billable codes under M43 (laterality / anatomic variants).