What term refers to involuntary contraction of a blood vessel?

• A. Brain death
• B. Vasospasm
• C. Occlusion
• D. AV Malformation

Answer: (B)

Vasospasm is the involuntary contraction of the smooth muscle in the wall of a blood vessel, causing the lumen to narrow. This physiological tightening reduces or alters blood flow downstream and can be a dynamic, reversible process rather than a fixed blockage. In the brain, cerebral vasospasm can occur after events like subarachnoid hemorrhage and is often monitored with Doppler studies that show higher flow velocities as the artery constricts. This concept is distinct from occlusion, which is a true blockage such as a clot blocking flow; brain death, which is the loss of all brain function; and an arteriovenous malformation, which is an abnormal tangle of vessels forming direct arterial-to-venous connections rather than transient vessel constriction.