I65.1 Occlusion and stenosis of basilar artery

Billable ICD-10-CM code, FY2026.

Applies from I65 Occlusion and stenosis of precerebral arteries, not resulting in cerebral infarction

Includes

• embolism of precerebral artery
• narrowing of precerebral artery
• obstruction (complete) (partial) of precerebral artery
• thrombosis of precerebral artery

Excludes1 (never code together)

• insufficiency, NOS, of precerebral artery (G45.-)
• insufficiency of precerebral arteries causing cerebral infarction (I63.0-I63.2)

MS-DRG index

Defines the logic of DRG(s) 061-063 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 433.00 Occlusion and stenosis of basilar artery without mention of cerebral infarction

Code annotations containing back-references to I65.1

Back-references to I65.1

• Type 2 Excludes: I74 Arterial embolism and thrombosis ("basilar embolism and thrombosis (I63.0-I63.2, I65.1)")

Back-references to I65

• Type 1 Excludes: G31.84 Mild cognitive impairment of uncertain or unknown etiology ("cerebrovascular diseases (I60-I69)")
• Code First: G46 Vascular syndromes of brain in cerebrovascular diseases ("underlying cerebrovascular disease (I60-I69)")
• Type 2 Excludes: I10 Essential (primary) hypertension ("essential (primary) hypertension involving vessels of brain (I60-I69)")
• Type 2 Excludes: I15 Secondary hypertension ("secondary hypertension involving vessels of brain (I60-I69)")

Diagnosis Index entries for I65.1

• Embolism (multiple) (paradoxical) › basilar (artery)
• Occlusion, occluded › artery › basilar

Nearby codes

• I65.0 Occlusion and stenosis of vertebral artery
• I65.01 Occlusion and stenosis of right vertebral artery
• I65.02 Occlusion and stenosis of left vertebral artery
• 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 (this code)
• 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