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I66Non-billableSave

I66 - Occlusion and stenosis of cerebral arteries, not resulting in cerebral infarction

ICD-10-CM Chapter 9: Diseases of the circulatory system · I60-I69 Cerebrovascular diseases (I60-I69) · Top-level category · FY2027

Coding Guidance

I66 is a non-billable heading. Report one of the 6 more specific codes below.

Includes, Excludes and Coding Notes

IncludesFrom I66

Conditions this code covers.

  • embolism of cerebral artery
  • narrowing of cerebral artery
  • obstruction (complete) (partial) of cerebral artery
  • thrombosis of cerebral artery
Excludes 1 — Not Coded HereFrom I66

Mutually exclusive: these conditions are never reported together with this code.

  • Occlusion and stenosis of cerebral artery causing cerebral infarction (I63.3-I63.5)
Excludes 1 — Not Coded HereFrom I60-I69 Cerebrovascular diseases (I60-I69)

Mutually exclusive: these conditions are never reported together with this code.

  • traumatic intracranial hemorrhage (S06.-)
Use Additional CodeFrom I60-I69 Cerebrovascular diseases (I60-I69)

Add a secondary code to identify the associated condition or cause when it is documented.

  • 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-I1A)
  • occupational exposure to environmental tobacco smoke (Z57.31)
  • tobacco dependence (F17.-)
  • tobacco use (Z72.0)
Excludes 2 — Not Included HereFrom Chapter I00-I99

Not part of this code; report both codes when the patient has both conditions.

  • 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.-)

More Specific Codes (6)

I66.0Occlusion and stenosis of middle cerebral artery→I66.1Occlusion and stenosis of anterior cerebral artery→I66.2Occlusion and stenosis of posterior cerebral artery→I66.3Occlusion and stenosis of cerebellar arteries→I66.8Occlusion and stenosis of other cerebral arteries→I66.9Occlusion and stenosis of unspecified cerebral artery→