When it comes to stroke, we often hear the phrase: “Time is Brain.” For years, stroke care emphasized that treatment must be delivered within a strict time window—the earlier, the better. While urgency remains crucial, recent advances in imaging and endovascular therapy have transformed how we determine eligibility for life-saving treatment.
One of the most revolutionary treatments for acute ischemic stroke is mechanical thrombectomy, a minimally invasive procedure that physically removes clots from blocked brain arteries. Traditionally offered only within 6 hours of symptom onset, new evidence shows that relying solely on the clock can exclude patients who may still benefit. This is where the concept of the tissue window comes in.
What is Mechanical Thrombectomy?
Mechanical thrombectomy involves threading a catheter through the blood vessels to the brain and removing the clot that is blocking blood flow. It has transformed outcomes for patients with large vessel occlusion (LVO), dramatically improving chances of recovery and long-term independence.
Time Window vs. Tissue Window
Time Window
Earlier guidelines restricted thrombectomy to within 6 hours of stroke onset, assuming brain tissue beyond that period would be irreversibly damaged.
Tissue Window
Modern imaging—such as CT perfusion or MRI—allows doctors to see:
- The core: brain tissue already dead
- The penumbra: at-risk tissue that is still salvageable
Even if a patient arrives 8, 12, or even 24 hours after symptom onset, thrombectomy can be beneficial if viable brain tissue remains.
Why the Tissue Window Approach Matters
- More Patients Benefit – Many strokes occur during sleep or go unnoticed at onset. A tissue-based approach ensures patients aren’t automatically excluded due to uncertain timing.
- Personalized Stroke Care – Not all strokes progress at the same rate. Some patients’ brains maintain better collateral blood flow, keeping tissue alive longer. Imaging allows individualized decisions.
- Proven by Landmark Trials – Trials such as DAWN and DEFUSE-3 demonstrated that carefully selected patients could benefit from thrombectomy up to 16–24 hours after stroke onset, shifting global guidelines.
- Better Outcomes, Less Disability – Focusing on salvageable tissue maximizes the chance of returning to independence instead of long-term disability.
A Call for Awareness
Healthcare providers, policymakers, and the public need to recognize this evolving paradigm:
- Stroke is an emergency—rapid action is essential.
- Patients should not be denied thrombectomy just because the time window has passed.
- Hospitals must adopt advanced imaging protocols to assess tissue viability and guide treatment.
The Bottom Line
Time is important—but tissue is paramount. Mechanical thrombectomy has redefined stroke treatment, and the tissue window approach ensures more lives are saved and more patients leave the hospital with independence intact.
If you or someone you know experiences stroke symptoms, remember FAST:
- F – Face drooping
- A – Arm weakness
- S – Speech difficulty
- T – Time to call emergency services
The earlier a patient reaches a stroke-ready center, the greater the chance of accessing advanced treatments like thrombectomy. Stroke care is no longer just about hours passed—it’s about the brain that can still be saved.
Dr. Tejesh Shavi
MBBS, DrNB Neurosurgery, FINR (SNVI)
Consultant – Interventional Neurosurgeon
