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G11.4

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🧬ICD-10 CM G11.4 - Hereditary spastic paraplegia

Overview

ICD-10 CM G11.4 classifies Hereditary Spastic Paraplegia (HSP), also known as familial spastic paraparesis. This is a group of rare, inherited neurological disorders characterized by progressive weakness and spasticity (stiffness) of the legs NCHS ICD-10-CM Tabular List 2025. The condition results from degeneration of the upper motor neurons in the corticospinal tract.

Accurate coding of G11.4 is essential for documenting the etiology of spasticity, distinguishing it from acquired forms (such as those due to trauma or cerebral palsy), and supporting medical necessity for genetic testing, physical therapy, and symptom management medications.

Code Breakdown

The structure of G11.4 follows the ICD-10-CM taxonomy:

SegmentValueDescription
CategoryG11Hereditary ataxia
SubcategoryG11.4Hereditary spastic paraplegia

Clinical Definition

Hereditary Spastic Paraplegia is characterized by progressive lower limb spasticity and weakness. It is classified into:

  • Uncomplicated (Pure): Involves only the lower limbs (spasticity, weakness, urinary urgency).
  • Complicated (Complex): Involves additional neurological symptoms (ataxia, dementia, neuropathy, optic atrophy, seizures) American Academy of Neurology.

Coding Guidelines

Includes

  • Hereditary spastic paraparesis.
  • Familial spastic paraplegia.
  • Strumpell-Lorrain disease.
  • Progressive hereditary spastic paraplegia.

Excludes

  • Spastic Cerebral Palsy: G80.1 (Spastic quadriplegic cerebral palsy) or G80.2 (Spastic hemiplegic cerebral palsy).
  • Spastic Paraplegia NOS: G82.10 (Spastic paraplegia, unspecified) - Use this if the hereditary nature is not documented.
  • Friedreich’s Ataxia: G11.1.
  • Other Hereditary Ataxias: G11.0 (Congenital nonprogressive ataxia), G11.2 (Late-onset cerebellar ataxia), G11.3 (Cerebellar ataxia with defective DNA repair).
  • Acquired Spasticity: Due to spinal cord injury, multiple sclerosis, or stroke (code the underlying condition).

Use of Additional Codes

G11.4 may be coded with additional codes to fully capture the clinical picture:

  • Genetic Testing Status: Z31.83 (Encounter for genetic testing) if testing is performed.
  • Family History: Z83.4 (Family history of other genetic disorders) if relevant to counseling.
  • Physical Therapy: Z71.89 (Other specified counseling) or procedure codes for PT.
  • Muscle Spasticity: G80.1 or G82.10 are generally excluded, but specific symptoms like urinary urgency (N39.41) or dysphagia (R13.10) may be coded if present and treated.
  • Assistive Device Dependence: Z99.81 (Dependence on wheelchair) or Z99.89 (Dependence on other enabling machines and devices).

Hereditary vs. Acquired

Ensure documentation supports the hereditary nature of the spastic paraplegia. If the provider documents “spastic paraplegia” without specifying hereditary, query for clarification. If confirmed as acquired (e.g., post-traumatic), G11.4 is invalid.

Risk Adjustment (HCC)

Hierarchical Condition Category (HCC) status determines impact on risk adjustment scores for Medicare Advantage and ACA plans.

  • HCC Status: No CMS-HCC V28
  • RAF Impact: This code does not directly contribute to the Risk Adjustment Factor (RAF) score under the current CMS-HCC V28 model.
  • Clinical Relevance: While not an HCC, this is a chronic, progressive condition requiring long-term management. It may trigger care management programs due to high resource utilization (therapy, medications, equipment).

Inpatient Impact (MS-DRG)

In the inpatient setting, G11.4 influences the Medicare Severity Diagnosis Related Group (MS-DRG) assignment.

  • CC/MCC Status: Non-CC (Not a Complication/Comorbidity) CMS MS-DRG v42
  • Impact: This code generally does not shift a DRG to a higher severity tier on its own. However, it supports medical necessity for admissions related to complication management (e.g., severe contractures, urinary infections) or rehabilitation.
  • POA Indicator: Present on Admission (POA) reporting is required for inpatient claims. Given the chronic hereditary nature, it is typically marked Y (Present on Admission).

Code Tree

Chapter 6: Diseases of the Nervous System (G00-G99)
└── Hereditary and degenerative diseases of the central nervous system (G10-G14)
    └── Hereditary ataxia (G11)
        └── G11.0 (Congenital nonprogressive ataxia)
        └── G11.1 (Friedreich's ataxia)
        └── G11.2 (Late-onset cerebellar ataxia)
        └── G11.3 (Cerebellar ataxia with defective DNA repair)
        └── G11.4 (Hereditary spastic paraplegia)
        └── G11.8 (Other hereditary ataxias)
        └── G11.9 (Hereditary ataxia, unspecified)

Clinical Coding Examples

Example 1: Initial Diagnosis

Scenario: A 35-year-old patient presents with progressive leg stiffness and weakness. Genetic testing confirms a mutation associated with hereditary spastic paraplegia. Coding:

  • Primary: G11.4
  • Secondary: Z31.83 (Encounter for genetic testing)

Example 2: Complicated HSP with Urinary Symptoms

Scenario: Patient with known G11.4 presents with urinary urgency and frequency. Coding:

Example 3: Rehabilitation Admission

Scenario: Patient admitted for intensive physical therapy due to worsening gait disturbance from HSP. Coding:

  • Primary: Z50.89 (Encounter for other rehabilitation procedures) - If rehab is the reason for admission.
  • Secondary: G11.4
  • Secondary: Z99.81 (Dependence on wheelchair) - If applicable.

Example 4: Unspecified Spastic Paraplegia

Scenario: Provider documents “Spastic Paraplegia” without mentioning hereditary or family history. Coding:

  • Primary: G82.10 (Spastic paraplegia, unspecified)
  • Note: Do not use G11.4 without documentation of hereditary etiology. Query the provider.

Revenue Cycle Considerations

  • wRVU: Not Applicable. ICD-10-CM codes do not have work Relative Value Units. wRVUs are assigned to CPT/HCPCS procedure codes.
  • Assistant Payable: Not Applicable. This attribute applies to surgical CPT codes.
  • Denial Risk: Moderate. Payers may request documentation supporting the hereditary diagnosis (e.g., genetic test results or family history) to approve certain medications or durable medical equipment (DME).
  • Prior Authorization: Treatments such as baclofen pumps (CPT 62360) or genetic testing (CPT 81479) typically require prior authorization with supporting documentation of G11.4.
  • G82.10: Spastic paraplegia, unspecified
  • G80.1: Spastic quadriplegic cerebral palsy
  • G11.1: Friedreich’s ataxia
  • G11.9: Hereditary ataxia, unspecified
  • Z99.81: Dependence on wheelchair
  • Z31.83: Encounter for genetic testing
  • G25.82: Stiff-man syndrome (Differential diagnosis)

Clinical Management Notes

Management of G11.4 is symptomatic and supportive National Organization for Rare Disorders:

  • Physical Therapy: To maintain muscle strength and prevent contractures.
  • Medications: Baclofen, tizanidine, or benzodiazepines for spasticity.
  • Interventions: Intrathecal baclofen pumps or orthopedic surgery for severe contractures.
  • Assistive Devices: Canes, walkers, or wheelchairs as mobility declines.

Documentation should support the medical necessity of these interventions when billing associated procedure codes.

CMS ICD-10-CM Official Guidelines for Coding and Reporting FY 2025 CMS-HCC Risk Adjustment Model V28 Summary CMS MS-DRG Definitions Manual v42 NCHS ICD-10-CM Tabular List 2025 American Academy of Neurology National Organization for Rare Disorders

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