2020 ICD-10-CM Diagnosis Code I66

Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

    2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
  • I66 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
  • Short description: Occls and stenosis of cereb art, not rslt in cerebral infrc
  • The 2020 edition of ICD-10-CM I66 became effective on October 1, 2019.
  • This is the American ICD-10-CM version of I66 - other international versions of ICD-10 I66 may differ.
Type 1 Excludes
Type 1 Excludes Help
A type 1 excludes note is a pure excludes. It means "not coded here". A type 1 excludes note indicates that the code excluded should never be used at the same time as I66. A type 1 excludes note is for used for when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
  • Occlusion and stenosis of cerebral artery causing cerebral infarction (
    ICD-10-CM Diagnosis Code I63.3

    Cerebral infarction due to thrombosis of cerebral arteries

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    I63.3-
    ICD-10-CM Diagnosis Code I63.5

    Cerebral infarction due to unspecified occlusion or stenosis of cerebral arteries

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    I63.5
    )
Includes
Includes Help
"Includes" further defines, or give examples of, the content of the code or category.
  • embolism of cerebral artery
  • narrowing of cerebral artery
  • obstruction (complete) (partial) of cerebral artery
  • thrombosis of cerebral artery
The following code(s) above I66 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to I66:
  • I00-I99
    2020 ICD-10-CM Range I00-I99

    Diseases of the circulatory system

    Type 2 Excludes
    • 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)
    • systemic connective tissue disorders (M30-M36)
    • transient cerebral ischemic attacks and related syndromes (G45.-)
    Diseases of the circulatory system
  • I60-I69
    2020 ICD-10-CM Range I60-I69

    Cerebrovascular diseases

    Type 1 Excludes
    • traumatic intracranial hemorrhage (S06.-)
    Use Additional
    • code to identify presence of:
    • alcohol abuse and dependence (F10.-)
    • exposure to environmental tobacco smoke (Z77.22)
    • history of tobacco dependence (Z87.891)
    • hypertension (I10-I16)
    • occupational exposure to environmental tobacco smoke (Z57.31)
    • tobacco dependence (F17.-)
    • tobacco use (Z72.0)
    Cerebrovascular diseases
Code History
  • 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
  • 2017 (effective 10/1/2016): No change
  • 2018 (effective 10/1/2017): No change
  • 2019 (effective 10/1/2018): No change
  • 2020 (effective 10/1/2019): No change
Code annotations containing back-references to I66:
  • Type 2 Excludes: I74
    ICD-10-CM Diagnosis Code I74

    Arterial embolism and thrombosis

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    Code First
    • embolism and thrombosis complicating abortion or ectopic or molar pregnancy (O00-O07, O08.2)
    • embolism and thrombosis complicating pregnancy, childbirth and the puerperium (O88.-)
    Includes
    • embolic infarction
    • embolic occlusion
    • thrombotic infarction
    • thrombotic occlusion
    Type 2 Excludes
ICD-10-CM Codes Adjacent To I66
I65.03 Occlusion and stenosis of bilateral vertebral arteries
I65.09 Occlusion and stenosis of unspecified vertebral artery
I65.1 Occlusion and stenosis of basilar artery
I65.2 Occlusion and stenosis of carotid artery
I65.21 Occlusion and stenosis of right carotid artery
I65.22 Occlusion and stenosis of left carotid artery
I65.23 Occlusion and stenosis of bilateral carotid arteries
I65.29 Occlusion and stenosis of unspecified carotid artery
I65.8 Occlusion and stenosis of other precerebral arteries
I65.9 Occlusion and stenosis of unspecified precerebral artery
I66 Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
I66.0 Occlusion and stenosis of middle cerebral artery
I66.01 Occlusion and stenosis of right middle cerebral artery
I66.02 Occlusion and stenosis of left middle cerebral artery
I66.03 Occlusion and stenosis of bilateral middle cerebral arteries
I66.09 Occlusion and stenosis of unspecified middle cerebral artery
I66.1 Occlusion and stenosis of anterior cerebral artery
I66.11 Occlusion and stenosis of right anterior cerebral artery
I66.12 Occlusion and stenosis of left anterior cerebral artery
I66.13 Occlusion and stenosis of bilateral anterior cerebral arteries
I66.19 Occlusion and stenosis of unspecified anterior cerebral artery

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.