2027 ICD-10-CM Diagnosis Code G23.1Progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski]
ICD-10-CM Codes›G00–G99›G20-G26›G23
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 199
- Chronic Condition
G23.1 is a billable ICD-10-CM diagnosis code for progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski]. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 56 through 57. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 23 closely related codes. Coders also document this condition as atypical progressive supranuclear palsy syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).
For Medicare Advantage risk adjustment, G23.1 maps to CMS-HCC Category 199 (Parkinson and Other Degenerative Disease of Basal Ganglia) under the V28 model, adding a risk factor of about 0.615 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
G23.1 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Atypical progressive supranuclear palsy syndrome
- Progressive supranuclear ophthalmoplegia
- Progressive supranuclear palsy
- Progressive supranuclear palsy corticobasal syndrome
- Progressive supranuclear palsy parkinsonism syndrome
- Progressive supranuclear palsy progressive non fluent aphasia
- Supranuclear gaze palsy
- Supranuclear paralysis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G23.1: its own notes plus those printed at G23 and Chapter 6. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Progressive supranuclear palsy
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- multi-system degeneration of the autonomic nervous system (G90.3)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name G23.1, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming G23.1: they are not reported together with it, unless the two conditions are unrelated.
- R25 Abnormal involuntary movements
Excludes2 2
These codes carry an Excludes2 note naming G23.1: its condition is not part of those codes, and both may be reported when the patient has both.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Ophthalmoplegia See Also: Strabismus, paralytic;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Progressive Supranuclear Palsy
Progressive supranuclear palsy (PSP) is a rare brain disease. It happens because of damage to nerve cells in the brain. PSP affects your movement, including control of your walking and balance. It also affects your thinking and eye movement.
The full article covers:
- What is progressive supranuclear palsy (PSP)?
- What causes progressive supranuclear palsy (PSP)?
- Who is at risk for progressive supranuclear palsy (PSP)?
- What are the symptoms of progressive supranuclear palsy (PSP)?
- How is progressive supranuclear palsy (PSP) diagnosed?
- What are the treatments for progressive supranuclear palsy (PSP)?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G23.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About G23.1Overview
What is the ICD-10 code for progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski]?
The ICD-10-CM code for progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski] is G23.1 (sometimes written as G231). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G23.1 (Other degenerative diseases of basal ganglia) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski] on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G23.1 group to?
When progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski] is the principal diagnosis on an inpatient stay, it groups to MS-DRG 57, 56, with relative weights from 1.2835 to 2.2649 depending on complications. Higher weights mean higher Medicare reimbursement.
Is G23.1 a CC or MCC?
CMS lists G23.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 23 closely related codes in its exclusion list.
What is the ICD-9 equivalent of G23.1?
Under the General Equivalence Mappings, progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski] converts to ICD-9-CM 333.0 (degen basal ganglia NEC). The mapping is approximate, so confirm the match fits the documentation.
What HCC is G23.1?
G23.1 (progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski]) maps to CMS-HCC Category 199 (Parkinson and Other Degenerative Disease of Basal Ganglia), commonly written as HCC 199, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 78 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 161.
Does G23.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G23.1 adds a risk adjustment factor of about 0.615 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.219 to 0.634 depending on the payment segment). HCC 199 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 199 category page.
