G11.0

🧬 ICD-10-CM G11.0 — Congenital Nonprogressive Ataxia

Billable Code Confirmed

ICD-10-CM G11.0 is a valid, billable 4-character diagnosis code. The first three characters (G11) specify hereditary ataxia, and the 4th character (0) specifies the congenital, non-progressive variant. No additional characters are required to report this code.

Non-Billable Parent Codes — Never Submit These

• ❌ G11 — 3-character header — Lacks specificity regarding the exact type or onset of the hereditary ataxia.

Always submit G11.0 (all 4 characters) when congenital nonprogressive ataxia is documented.

Clinical Context: Differentiating Ataxias

ICD-10-CM G11.0 represents a group of rare, early-onset ataxias that are present at birth or manifest in early infancy. Crucially, as the name implies, the neurological deficits do not progressively worsen over time. This distinguishes it from early-onset progressive ataxias (like Friedreich’s ataxia) and acquired ataxias.

Code Classification

ICD-10-CM Diagnosis Code — wRVU, assistant payable, and global period fields are not applicable. See CPT Procedural Crosswalk and ICD-10-PCS Crosswalk sections for associated procedural billing.

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🔍 Code Description

ICD-10-CM G11.0 classifies Congenital non-progressive ataxia (NPCA). This is a clinical syndrome characterized by early-onset cerebellar ataxia (incoordination, unsteady gait, dysmetria, intention tremor) that remains relatively static throughout the patient’s life.

Pathophysiologically, it is often associated with maldevelopment of the cerebellum, such as cerebellar hypoplasia or dysplasia, which can be visualized on neuroimaging. Patients typically present with delayed achievement of early motor milestones (e.g., sitting, walking unsupported) and pronounced hypotonia, which eventually evolves into a recognizable ataxic pattern as the child grows.

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🌳 Code Tree / Hierarchy

G11 Hereditary ataxia ❌ Non-billable
│
├── G11.0 Congenital nonprogressive ataxia ◀ THIS CODE ✅ Billable
├── G11.1- Early-onset cerebellar ataxia 
├── G11.2 Late-onset cerebellar ataxia ✅ Billable
├── G11.3 Cerebellar ataxia with defective DNA repair ✅ Billable
├── G11.4 Hereditary spastic paraplegia ✅ Billable
├── G11.8 Other hereditary ataxias ✅ Billable
└── G11.9 Hereditary ataxia, unspecified ✅ Billable

Congenital vs. Early-Onset

While both G11.0 and the G11.1- subcategory can present early in life, the distinguishing factor for [[G11.0]] is its nonprogressive clinical course. If the provider documents the ataxia as “early-onset” and “progressive,” refer to the G11.1- series instead.

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✅ Includes

The following clinical terms and scenarios map to G11.0 when documented:

• Congenital cerebellar ataxia
• Non-progressive congenital ataxia (NPCA)
• Ataxia with congenital cerebellar hypoplasia (without progressive decline)

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❌ Excludes

Excludes 1 — Cannot Be Coded Simultaneously with CODE

Code	Description	Note
G80.4	Ataxic cerebral palsy	Mutually exclusive. Ataxic CP is caused by a non-progressive injury to the developing brain (often perinatally), whereas G11.0 typically denotes a primary developmental/genetic non-progressive malformation of the cerebellum.
G11.1-	Early-onset cerebellar ataxia	Mutually exclusive. G11.1- codes represent progressive ataxias (like Friedreich ataxia) despite their early onset.

Excludes 2 — May Be Coded in Addition if Separately Present

Code	Description	Note
E70-E88	Metabolic disorders	Patients with congenital ataxia may also have a concomitant, distinct metabolic disorder.
G60.-	Hereditary and idiopathic neuropathy	May be coded simultaneously if the patient has a distinct peripheral neuropathy along with central congenital ataxia.

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📋 Clinical Overview

Common Diagnoses / Clinical Indications

Patients assigned this code typically present in early childhood with:

• Delayed Motor Milestones: Late sitting, standing, or walking.
• Truncal and Appendicular ataxia: Wide-based, unsteady gait, clumsiness, and frequent falls.
• Hypotonia: “Floppy infant” presentation early in life.
• Speech Impairment: Dysarthria or delayed speech development.
• Oculomotor Abnormalities: Nystagmus, strabismus, or ocular dysmetria.

Coding Manifestations and Symptoms

In an outpatient setting, if the definitive diagnosis of “congenital non-progressive ataxia” has not yet been established by the specialist, code the signs and symptoms instead (e.g., R27.0 Ataxia, unspecified; R62.50 Unspecified lack of expected normal physiological development in childhood).

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💰 HCC Risk Adjustment (CMS-HCC v28)

Field	Detail
CMS-HCC Model Version	v28 (2024-2025 Implementation)
HCC Assignment	✅ Mapped — HCC 72 / 76 (depending on exact crosswalk logic)
HCC Category	Spinal Cord Disorders / Neurological Conditions

G11.0 maps to CMS-HCC models indicating chronic neurological complexity. Because this is a lifelong congenital condition, providers must document and code it during an active face-to-face encounter every calendar year to ensure the patient’s risk profile remains accurate.

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🏥 DRG Assignment

MDC 01 — Diseases and Disorders of the Nervous System

DRG	Title	Est. Relative Weight*
DRG 056	Degenerative Nervous System Disorders with MCC	~1.65
DRG 057	Degenerative Nervous System Disorders without MCC	~0.95

Approximate. Verify against IPPS FY2026 Final Rule tables.

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🛠️ Commonly Associated CPT Codes (Profee / Outpatient)

Outpatient Setting Context

Management of congenital nonprogressive ataxia typically occurs in outpatient pediatric neurology or genetic clinics, involving extensive evaluations and imaging.

CPT Code	Description	Modifier Notes / wRVU
99205	Office or other outpatient visit for the evaluation and management of a new patient (High MDM, or 60-74 mins)	Commonly billed for the initial comprehensive pediatric neurology workup. (wRVU: 3.16)
99214	Office or other outpatient visit for an established patient (Moderate MDM)	Used for routine follow-up, symptom management, and therapy coordination. (wRVU: 1.92)
70551	Magnetic resonance (e.g., proton) imaging, brain; without contrast material	Billed with Modifier -26 by the interpreting physician. Crucial for identifying cerebellar hypoplasia.
81400-81408	Molecular pathology procedures (Tier 2)	Various genetic testing codes may be used to identify specific genetic mutations causing congenital ataxias.

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💊 Coding Scenarios and Examples

Scenario 1 — Pediatric Neurology Initial Eval

Clinical Vignette: A 2-year-old child is referred to pediatric neurology due to severe delays in walking and a notably clumsy, wide-based gait. The mother notes the child was hypotonic as an infant. MRI of the brain, previously ordered by the pediatrician, shows generalized cerebellar hypoplasia. The neurologist completes a comprehensive history and exam (High MDM) and diagnoses the child with non-progressive congenital ataxia, ordering physical and speech therapy.

Diagnoses:

• G11.0 — Congenital nonprogressive ataxia (Primary reason for the visit/diagnosis)

Procedure:

• 99205 — E/M new patient, High MDM

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Scenario 2 — Differentiating CP vs. NPCA

Clinical Vignette: A 4-year-old patient with an established diagnosis of “ataxic cerebral palsy” presents to a new neurologist. Upon reviewing birth records (which show a completely normal perinatal course without hypoxic injury) and current imaging (showing specific cerebellar dysplasia), the neurologist documents: “Patient does not have cerebral palsy; symptoms and imaging are consistent with congenital nonprogressive ataxia.”

Corrected ICD-10-CM Coding:

• G11.0 — Congenital nonprogressive ataxia
• Do not code G80.4 (Ataxic cerebral palsy) as it was explicitly ruled out/corrected by the specialist and is an Excludes1.

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⚠️ Coding Pitfalls and Tips

	Pitfall or Tip
❌	Mistaking NPCA for Ataxic Cerebral Palsy. Do not default to G80.4 (Ataxic CP) just because an infant is clumsy or ataxic. If the provider specifically documents “congenital ataxia” or “cerebellar hypoplasia,” query to confirm if G11.0 is the appropriate diagnosis. These codes are subject to an Excludes1 edit.
❌	Using G11.0 for Progressive Conditions. If the medical record indicates the child is losing previously acquired motor milestones (regression) or the ataxia is worsening, G11.0 is incorrect. Look toward progressive codes like Friedreich ataxia (G11.11) or unspecified early-onset ataxia (G11.10).
✅	Code Associated Delays Initially. If the physician has not yet confirmed the congenital nonprogressive nature of the ataxia, use symptom codes like R27.0 (ataxia) or R62.50 (Lack of normal physiological development) until the formal diagnosis is rendered.^5
✅	Capture Annually for HCC. For risk adjustment purposes, even though the condition is “nonprogressive” and stable, it is a permanent condition that adds medical complexity and must be reported face-to-face once per calendar year.

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📚 Sources

1. CMS/NCHS. ICD-10-CM Official Guidelines for Coding and Reporting, FY2025/FY2026. Chapter 6: Diseases of the Nervous System.
2. American Academy of Neurology (AAN). Consensus guidelines on the evaluation of pediatric ataxia.
3. Fogel, B. L. (2012). Childhood cerebellar ataxia. Journal of Child Neurology, 27(9), 1138-1145. (Source for clinical presentation and distinction from progressive ataxias).
4. CMS. 2025-2026 Medicare Advantage Risk Adjustment — CMS-HCC Model v28 ICD-10-CM Mappings.
5. American Medical Association (AMA). CPT Professional Edition 2025. Evaluation and Management Guidelines.