2027 ICD-10-CM Diagnosis Code G12.23Primary lateral sclerosis
ICD-10-CM Codes›G00–G99›G10-G14›G12
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 190
- Chronic Condition
G12.23 is a billable ICD-10-CM diagnosis code for primary lateral sclerosis. 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 111 closely related codes. Coders also document this condition as juvenile primary lateral sclerosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other nervous system disorders (often hereditary or degenerative).
For Medicare Advantage risk adjustment, G12.23 maps to CMS-HCC Category 190 (Amyotrophic Lateral Sclerosis and Other Motor Neuron Disease, Spinal Muscular Atrophy) under the V28 model, adding a risk factor of about 1.175 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
G12.23 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.
- Juvenile primary lateral sclerosis
- Primary lateral sclerosis
- Upper motor neuron disease
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to G12.23: its own notes plus those printed at Chapter 6. A note printed at a category, block or chapter applies to every code under it.
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.
- 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.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Primary Lateral Sclerosis
a progressive neurodegenerative disorder affecting upper motor neurons, characterized by progressive muscle weakness.Motor Neuron Disease
diseases characterized by a selective degeneration of the motor neurons of the spinal cord, brainstem, or motor cortex. clinical subtypes are distinguished by the major site of degeneration. in amyotrophic lateral sclerosis there is involvement of upper, lower, and brainstem motor neurons. in progressive muscular atrophy and related syndromes (see muscular atrophy, spinal) the motor neurons in the spinal cord are primarily affected. with progressive bulbar palsy (bulbar palsy, progressive), the initial degeneration occurs in the brainstem. in primary lateral sclerosis, the cortical neurons are affected in isolation. (adams et al., principles of neurology, 6th ed, p1089)
Patient EducationClinical
Neuromuscular Disorders
Neuromuscular disorders affect your neuromuscular system. They can cause problems with:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert G12.23 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code History & ChangesHistory
Replacement G12.23 replaces the following previously assigned code(s):
- G12.29 - Other motor neuron disease
Questions About G12.23Overview
What is the ICD-10 code for primary lateral sclerosis?
The ICD-10-CM code for primary lateral sclerosis is G12.23 (sometimes written as G1223). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is G12.23 (Motor neuron disease) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report primary lateral sclerosis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does G12.23 group to?
When primary lateral sclerosis 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 G12.23 a CC or MCC?
CMS lists G12.23 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 111 closely related codes in its exclusion list.
What is the ICD-9 equivalent of G12.23?
Under the General Equivalence Mappings, primary lateral sclerosis converts to ICD-9-CM 335.24 (prim lateral sclerosis). The mapping is a direct match.
What HCC is G12.23?
G12.23 (primary lateral sclerosis) maps to CMS-HCC Category 190 (Amyotrophic Lateral Sclerosis and Other Motor Neuron Disease, Spinal Muscular Atrophy), commonly written as HCC 190, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 73 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 154.
Does G12.23 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, G12.23 adds a risk adjustment factor of about 1.175 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.628 to 3.642 depending on the payment segment). HCC 190 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 190 category page.
