ICD10BillableValid for clinical use
ICD-10 Code I66.9: Occlusion and stenosis of unspecified cerebral artery
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 circulatory system (I00-I99).
When is it used?
- May be used when a clinician documents occlusion and stenosis of unspecified cerebral artery 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
9Diseases of the circulatory system (I00-I99)
block
I60-I69Cerebrovascular diseases
category
I66Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
currentI66
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
CardiologistGeneral Physician
Related codes
I66.0Occlusion and stenosis of middle cerebral arterycategoryI66.1Occlusion and stenosis of anterior cerebral arterycategoryI66.2Occlusion and stenosis of posterior cerebral arterycategoryI66.3Occlusion and stenosis of cerebellar arteriescodeI66.8Occlusion and stenosis of other cerebral arteriescode
Sibling codes
Coverage-related procedures and services
CPT 93319high
3D ECHOCARDIOGRAPHIC IMAGING AND POSTPROCESSING DURING TRANSESOPHAGEAL ECHOCARDIOGRAPHY, OR DURING TRANSTHORACIC ECHOCARDIOGRAPHY FOR CONGENITAL CARDIAC ANOMALIES, FOR THE ASSESSMENT OF CARDIAC STRUCTURE(S) (EG, CARDIAC CHAMBERS AND VALVES, LEFT ATRIAL APPENDAGE, INTERATRIAL SEPTUM, INTERVENTRICULAR SEPTUM) AND FUNCTION, WHEN PERFORMED (LIST SEPARATELY IN ADDITION TO CODE FOR ECHOCARDIOGRAPHIC IMAGING)
Source: CMS coverage guidance
CPT 76376high
3D RENDERING WITH INTERPRETATION AND REPORTING OF COMPUTED TOMOGRAPHY, MAGNETIC RESONANCE IMAGING, ULTRASOUND, OR OTHER TOMOGRAPHIC MODALITY WITH IMAGE POSTPROCESSING UNDER CONCURRENT SUPERVISION; NOT REQUIRING IMAGE POSTPROCESSING ON AN INDEPENDENT WORKSTATION
Source: CMS coverage guidance
CPT 76377high
3D RENDERING WITH INTERPRETATION AND REPORTING OF COMPUTED TOMOGRAPHY, MAGNETIC RESONANCE IMAGING, ULTRASOUND, OR OTHER TOMOGRAPHIC MODALITY WITH IMAGE POSTPROCESSING UNDER CONCURRENT SUPERVISION; REQUIRING IMAGE POSTPROCESSING ON AN INDEPENDENT WORKSTATION
Source: CMS coverage guidance
CPT 95940high
CONTINUOUS INTRAOPERATIVE NEUROPHYSIOLOGY MONITORING IN THE OPERATING ROOM, ONE ON ONE MONITORING REQUIRING PERSONAL ATTENDANCE, EACH 15 MINUTES (LIST SEPARATELY IN ADDITION TO CODE FOR PRIMARY PROCEDURE)
Source: CMS coverage guidance
HCPCS G0453high
CONTINUOUS INTRAOPERATIVE NEUROPHYSIOLOGY MONITORING, FROM OUTSIDE THE OPERATING ROOM (REMOTE OR NEARBY), PER PATIENT, (ATTENTION DIRECTED EXCLUSIVELY TO ONE PATIENT) EACH 15 MINUTES (LIST IN ADDITION TO PRIMARY PROCEDURE)
Source: CMS coverage guidance
CPT 93325high
DOPPLER ECHOCARDIOGRAPHY COLOR FLOW VELOCITY MAPPING (LIST SEPARATELY IN ADDITION TO CODES FOR ECHOCARDIOGRAPHY)
Source: CMS coverage guidance
Mapped diagnoses and classifications
SNOMED_CT 724427002high
Asymptomatic stenosis of intracranial artery
Source: SNOMED International ICD-10 map
SNOMED_CT 1263547004high
Benign intracranial hypertension due to thrombus of intracranial vein
Source: SNOMED International ICD-10 map
SNOMED_CT 20059004high
Cerebral artery occlusion
Source: SNOMED International ICD-10 map
SNOMED_CT 75543006high
Cerebral embolism
Source: SNOMED International ICD-10 map
SNOMED_CT 472746006high
Cerebrovascular disorder due to paradoxical embolus
Source: SNOMED International ICD-10 map
SNOMED_CT 1204128009high
Cholesterol atheroembolism of cerebrum
Source: SNOMED International ICD-10 map
Coding guidelines
Compatibility
Legacy and official ICD code match exactly.
Legacy codes
I66.9
Common synonyms
Occlusion and stenosis of unspecified cerebral arteryOcclusion and stenosis of cerebral artery
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.