G90.2 Horner's syndrome

The ICD-10-CM code for Horner's syndrome is G90.2 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

6: Diseases of the nervous system (G00-G99)

Section

G89-G99: Other disorders of the nervous system (G89-G99)

Category G90

27 codes (21 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to G90.2:

• Claude Bernard-Horner syndrome
• Bernard-Horner syndrome
• Horner (-Claude Bernard) syndrome
• Dystrophy, dystrophia › cervical sympathetic
• Syndrome › Horner's
• Dystrophy, dystrophia › sympathetic (reflex) › cervical
• Syndrome › cervical (root) › sympathetic paralysis
• Syndrome › sympathetic › cervical paralysis

Inclusion Terms

• Bernard(-Horner) syndrome
• Cervical sympathetic dystrophy or paralysis

U.S. Hospital Utilization

• An estimated 3,705 U.S. inpatient stays in 2023 included G90.2 among the documented diagnoses.
• 145 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Dominant/nondominant side (TOC entry)

a. Dominant/nondominant side ................................................................................................. 45

Pain - Category G89 (TOC entry)

b. Pain - Category G89.............................................................................................................. 45

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)