I63.342

HCC Category Mapping

What This Code Means

A stroke caused by a blood clot blocking the left cerebellar artery, affecting the left side of the cerebellum.

Coding Tips

• •Confirm left-sided cerebellar involvement through imaging documentation
• •Document any associated cerebellar symptoms such as ataxia or vertigo in the medical record

Clinical Significance

This code identifies an acute ischemic stroke caused by thrombosis (in-situ clot formation) of the left cerebellar artery, requiring precise documentation of the clot mechanism. The cerebellar arteries (posterior inferior, anterior inferior, and superior) supply the cerebellum. Infarction can cause life-threatening posterior fossa swelling. Accurate coding of the mechanism, artery, and laterality is critical for risk adjustment and tracking stroke subtypes for quality measures and secondary prevention strategies.

Documentation Requirements

• ✓Provider documentation of acute cerebral infarction (stroke) as a confirmed diagnosis, not rule-out or suspected
• ✓Identification of the affected artery as the cerebellar artery
• ✓Documentation of laterality (left) supported by clinical findings and/or imaging
• ✓Documentation that thrombosis (in-situ clot formation) is the underlying mechanism, typically supported by vascular imaging such as computed tomography angiography or magnetic resonance angiography
• ✓Neurological examination findings consistent with the identified vascular territory (e.g., acute vertigo, ataxia, dysarthria, nausea/vomiting, nystagmus, and risk of brainstem compression from cerebellar edema)
• ✓Brain imaging (computed tomography or magnetic resonance imaging) confirming acute infarction
• ✓Timing of symptom onset to confirm acute presentation
• ✓Documentation of stroke severity (National Institutes of Health Stroke Scale score preferred)
• ✓Treatment administered (thrombolytics, thrombectomy, antiplatelet therapy, anticoagulation)

Commonly Confused Codes