Which change in Doppler flow characteristics corresponds to deterioration of cerebral perfusion leading toward brain death?

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

Answer: (B)

The main idea here is how Doppler signals change as cerebral perfusion worsens. When vessels constrict in a process called vasospasm, the lumen narrows and the same amount of blood has to pass through a tighter space. On Doppler, this shows up as higher flow velocities in the affected arteries, often with more pulsatile flow and reduced diastolic contribution as downstream resistance rises. That pattern reflects growing ischemia and deteriorating brain perfusion, and it can progress toward brain death if perfusion becomes critically low.

So, vasospasm best fits the scenario of worsening cerebral perfusion leading toward brain death because it represents a dynamic, progressive loss of blood supply due to vessel constriction. In contrast, brain death would imply an eventual absence of intracranial flow rather than a progressive velocity increase; an AV malformation causes abnormal, turbulent high-velocity flow from abnormal connections rather than a stepwise decline in perfusion; and occlusion would cause an abrupt loss of flow in the affected territory rather than the gradual deterioration associated with vasospasm.