Reversible cerebrovascular vasoconstriction syndrome

This code identifies a neurological disorder characterized by sudden, severe headaches, often described as thunderclap headaches, accompanied by transient narrowing of cerebral blood vessels. These vasoconstrictions are reversible, typically resolving spontaneously within weeks to months, and are not associated with permanent brain damage or stroke.

Assign this code when documentation confirms a diagnosis of Reversible Cerebral Vasoconstriction Syndrome (RCVS), often following imaging studies like CT angiography or MR angiography demonstrating multifocal segmental vasoconstriction. This diagnosis is typically made after excluding other causes of thunderclap headache, such as subarachnoid hemorrhage or vasculitis.

• Ensure documentation explicitly states "reversible" to differentiate from other forms of cerebral vasculopathy.
• Do not confuse with other types of cerebral vasculitis (I67.7) or unspecified cerebrovascular disease (I67.9).
• Code any associated symptoms, such as headache (R51.9), as secondary diagnoses.