ICD10BillableValid for clinical use
ICD-10 Code G31.9: Degenerative disease of nervous system, unspecified
Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026
What is this code?
ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the nervous system (G00-G99).
When is it used?
- May be used when a clinician documents degenerative disease of nervous system, unspecified in a patient's medical record.
- May appear in hospital records, claims, referrals, and clinical documentation.
- This code can be used as a clinically usable diagnosis entry in standardized coding workflows.
What it does not mean
- A code alone does not explain severity, treatment plan, or outcome.
- A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
Code hierarchy
chapter
6Diseases of the nervous system (G00-G99)
block
G30-G32Other degenerative diseases of the nervous system
category
G31Other degenerative diseases of nervous system, not elsewhere classified
currentG31
Where you may see this code
You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.
Related specialists
NeurologistGeneral Physician
Related codes
Sibling codes
Coverage-related procedures and services
CPT 96105high
ASSESSMENT OF APHASIA (INCLUDES ASSESSMENT OF EXPRESSIVE AND RECEPTIVE SPEECH AND LANGUAGE FUNCTION, LANGUAGE COMPREHENSION, SPEECH PRODUCTION ABILITY, READING, SPELLING, WRITING, EG, BY BOSTON DIAGNOSTIC APHASIA EXAMINATION) WITH INTERPRETATION AND REPORT, PER HOUR
Source: CMS coverage guidance
CPT 78608high
BRAIN IMAGING, POSITRON EMISSION TOMOGRAPHY (PET); METABOLIC EVALUATION
Source: CMS coverage guidance
CPT 96113high
DEVELOPMENTAL TEST ADMINISTRATION (INCLUDING ASSESSMENT OF FINE AND/OR GROSS MOTOR, LANGUAGE, COGNITIVE LEVEL, SOCIAL, MEMORY AND/OR EXECUTIVE FUNCTIONS BY STANDARDIZED DEVELOPMENTAL INSTRUMENTS WHEN PERFORMED), BY PHYSICIAN OR OTHER QUALIFIED HEALTH CARE PROFESSIONAL, WITH INTERPRETATION AND REPORT; EACH ADDITIONAL 30 MINUTES (LIST SEPARATELY IN ADDITION TO CODE FOR PRIMARY PROCEDURE)
Source: CMS coverage guidance
CPT 96112high
DEVELOPMENTAL TEST ADMINISTRATION (INCLUDING ASSESSMENT OF FINE AND/OR GROSS MOTOR, LANGUAGE, COGNITIVE LEVEL, SOCIAL, MEMORY AND/OR EXECUTIVE FUNCTIONS BY STANDARDIZED DEVELOPMENTAL INSTRUMENTS WHEN PERFORMED), BY PHYSICIAN OR OTHER QUALIFIED HEALTH CARE PROFESSIONAL, WITH INTERPRETATION AND REPORT; FIRST HOUR
Source: CMS coverage guidance
HCPCS A9601high
FLORTAUCIPIR F 18 INJECTION, DIAGNOSTIC, 1 MILLICURIE
Source: CMS coverage guidance
HCPCS A9552high
FLUORODEOXYGLUCOSE F-18 FDG, DIAGNOSTIC, PER STUDY DOSE, UP TO 45 MILLICURIES
Source: CMS coverage guidance
Mapped diagnoses and classifications
SNOMED_CT 691461000119103high
Acquired cerebral atrophy
Source: SNOMED International ICD-10 map
SNOMED_CT 417017003high
Acute cerebellar syndrome
Source: SNOMED International ICD-10 map
SNOMED_CT 1144386003high
Atrophy of Purkinje cells of cerebellar cortex
Source: SNOMED International ICD-10 map
SNOMED_CT 1144381008high
Atrophy of brainstem
Source: SNOMED International ICD-10 map
SNOMED_CT 1144383006high
Atrophy of caudate nucleus
Source: SNOMED International ICD-10 map
SNOMED_CT 1144387007high
Atrophy of cerebellar vermis
Source: SNOMED International ICD-10 map
Coding guidelines
Compatibility
Legacy and official ICD code match exactly.
Legacy codes
G31.9
Common synonyms
Degenerative disease of nervous system, unspecifiedDegenerative disease of nervous system
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.