2023 ICD-10-CM Diagnosis Code I66.9

Occlusion and stenosis of unspecified cerebral artery

    2016 2017 2018 2019 2020 2021 2022 2023 Billable/Specific Code
  • I66.9 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2023 edition of ICD-10-CM I66.9 became effective on October 1, 2022.
  • This is the American ICD-10-CM version of I66.9 - other international versions of ICD-10 I66.9 may differ.
The following code(s) above I66.9 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 I66.9:
  • I00-I99
    2023 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
    2023 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
  • I66
    ICD-10-CM Diagnosis Code I66

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

      2016 2017 2018 2019 2020 2021 2022 2023 Non-Billable/Non-Specific Code
    Includes
    • embolism of cerebral artery
    • narrowing of cerebral artery
    • obstruction (complete) (partial) of cerebral artery
    • thrombosis of cerebral artery
    Type 1 Excludes
    • Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)
    Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction
Approximate Synonyms
  • Cerebral artery occlusion
  • Cerebral embolism
  • Cerebral thrombosis
  • Occlusion and stenosis of multiple and bilateral cerebral arteries
  • Occlusion of cerebral artery
  • Occlusion or stenosis of multiple cerebral arteries
  • Stenosis of multiple cerebral arteries
  • Thrombosis of cerebral artery
ICD-10-CM I66.9 is grouped within Diagnostic Related Group(s) (MS-DRG v40.0):
  • 061 Ischemic stroke, precerebral occlusion or transient ischemia with thrombolytic agent with mcc
  • 062 Ischemic stroke, precerebral occlusion or transient ischemia with thrombolytic agent with cc
  • 063 Ischemic stroke, precerebral occlusion or transient ischemia with thrombolytic agent without cc/mcc
  • 067 Nonspecific cva and precerebral occlusion without infarction with mcc
  • 068 Nonspecific cva and precerebral occlusion without infarction without mcc
  • 791 Prematurity with major problems
  • 793 Full term neonate with major problems

Convert I66.9 to ICD-9-CM

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
  • 2021 (effective 10/1/2020): No change
  • 2022 (effective 10/1/2021): No change
  • 2023 (effective 10/1/2022): No change

Diagnosis Index entries containing back-references to I66.9:

ICD-10-CM Codes Adjacent To I66.9
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
I66.2 Occlusion and stenosis of posterior cerebral artery
I66.21 Occlusion and stenosis of right posterior cerebral artery
I66.22 Occlusion and stenosis of left posterior cerebral artery
I66.23 Occlusion and stenosis of bilateral posterior cerebral arteries
I66.29 Occlusion and stenosis of unspecified posterior cerebral artery
I66.3 Occlusion and stenosis of cerebellar arteries
I66.8 Occlusion and stenosis of other cerebral arteries
I66.9 Occlusion and stenosis of unspecified cerebral artery
I67 Other cerebrovascular diseases
I67.0 Dissection of cerebral arteries, nonruptured
I67.1 Cerebral aneurysm, nonruptured
I67.2 Cerebral atherosclerosis
I67.3 Progressive vascular leukoencephalopathy
I67.4 Hypertensive encephalopathy
I67.5 Moyamoya disease
I67.6 Nonpyogenic thrombosis of intracranial venous system
I67.7 Cerebral arteritis, not elsewhere classified
I67.8 Other specified cerebrovascular diseases

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