Other malformations of precerebral vessels

This code signifies congenital structural abnormalities affecting the arteries and veins that supply blood to the brain, excluding those within the brain itself (intracranial). These malformations can involve the carotid arteries, vertebral arteries, or their major branches in the neck and base of the skull. They represent developmental defects present at birth, rather than acquired conditions.

Use this code for documented congenital anomalies of the extracranial cerebral vasculature, such as an aberrant origin of a vertebral artery, hypoplasia of a carotid artery, or a persistent fetal carotid-basilar anastomosis. Documentation should clearly specify a congenital origin and the specific precerebral vessel involved, distinguishing it from intracranial vascular malformations.

• Differentiate from acquired conditions like atherosclerosis or dissection; this code is strictly for congenital malformations.
• Ensure documentation specifies "precerebral" or "extracranial" to avoid confusion with intracranial malformations (e.g., AVMs coded elsewhere).
• Do not use for unspecified cerebrovascular disease; a specific congenital malformation of a precerebral vessel must be identified.