Viva · IR system
Neurointervention Viva Questions
Oral-exam style questions and answers on neurointervention for MD, DNB and super-specialty practical examinations. Each answer links back to the playbook or Library entry it was written from.
- Your patient is neurologically intact throughout a 30 minute occlusion but the venous phase on the tested side lags the control hemisphere by 3.5 seconds. Do you sacrifice the carotid?
- No, not on that result alone. Clinical tolerance at rest only shows perfusion is above the threshold for symptoms, whereas venous delay reflects exhausted collateral reserve, and delay in this range predicts delayed infarction after permanent occlusion. Add a hypotensive challenge or perfusion imaging, and plan bypass or a reconstructive strategy if the result remains borderline.
- Why does balloon position relative to the carotid bulb matter, and what happens if you get it wrong?
- Inflation within or immediately above the bulb stimulates carotid sinus baroreceptors, causing bradycardia and systemic hypotension. That simultaneously drops collateral perfusion pressure and confounds the neurological assessment, producing a false positive test in a patient who would in fact have tolerated occlusion.
- The patient develops dense hemiparesis at 12 minutes. You deflate and it does not resolve after 10 minutes. What is your reasoning and what do you do?
- Haemodynamic ischaemia reverses within minutes of restoring flow, so a persistent deficit after deflation indicates thromboembolism rather than collateral failure. Check the activated clotting time, give further heparin, and perform immediate angiography with a view to mechanical thrombectomy of a large vessel occlusion.
- How does a fetal posterior cerebral artery on the side being tested change your interpretation?
- It means the occipital lobe is supplied by the tested internal carotid artery rather than the basilar, so occlusion removes both anterior and posterior circulation supply to that hemisphere and there is no posterior communicating collateral to recruit. The territory at risk is larger and a pass should be regarded with more caution.
- Why must the patient not be sedated, and what do you do if they cannot cooperate?
- Serial neurological examination is the primary endpoint of the test and sedation abolishes it, leaving only surrogate angiographic and pressure measures. In an uncooperative patient, either abandon clinical BTO and rely on quantitative perfusion imaging during occlusion, or reconsider a reconstructive rather than deconstructive strategy.
- What does a stump pressure ratio of 45 percent tell you in a patient with no deficit and symmetric venous phase?
- It indicates collateral perfusion pressure below the accepted 60 percent threshold, so the patient has functional but low-pressure collateral supply that may fail under any future hypotensive stress. This is the classic indication to proceed to a hypotensive challenge or perfusion imaging rather than accepting the test as passed.
- Why is catheter cerebral angiography still considered the reference standard?
- It provides the highest spatial and temporal resolution, selective vessel assessment and direct visualization of arterial, capillary and venous phases. It is especially valuable for small aneurysms, collateral circulation and the haemodynamics of AVMs or dural fistulas.
- What is the difference between four-vessel and six-vessel cerebral angiography?
- Four-vessel angiography consists of bilateral internal carotid and bilateral vertebral injections. Six-vessel angiography adds bilateral external carotid injections, which are essential when evaluating dural fistulas, vascular malformations and hypervascular tumours.
- What is the most feared complication and how do you prevent it?
- The most feared complication is thromboembolic stroke. Prevention requires continuous air-free heparinized flushing, aspiration and flushing after wire removal or catheter exchange, gentle catheter manipulation, avoidance of diseased plaque and repeated neurological assessment.
- Which catheter is useful in a type III aortic arch?
- A Simmons 2 or another reverse-curve catheter is commonly useful because its secondary curve provides support for selecting superiorly directed great-vessel origins. It must be reformed and manipulated under fluoroscopy without force.
- Why should a diagnostic cerebral angiogram include the venous phase?
- The venous phase defines drainage pattern, stenosis, outflow obstruction and cortical venous reflux. These findings are essential for classifying AVMs and dural fistulas and estimating haemorrhagic risk.
- How is carotid stenosis measured by the NASCET method?
- Percentage stenosis equals **1 minus the minimum residual lumen divided by the normal distal cervical ICA lumen, multiplied by 100**. The distal reference artery must be beyond the bulb where the walls are parallel.
- What should you do if contrast stagnates during a test injection?
- Stop injecting immediately because the catheter may be wedged or the vessel may be in spasm or dissected. Withdraw to a larger-calibre segment and exclude injury with a gentle proximal injection before proceeding.
- What is the immediate response to a new neurological deficit during angiography?
- Stop the diagnostic study, stabilize airway and haemodynamics, perform a focused neurological examination and identify an angiographic occlusion or dissection. Activate the institutional stroke and neurointerventional rescue pathway without delay.
- A patient with an indirect cavernous shunt has minimal proptosis but the angiogram shows filling of the superficial middle cerebral vein. How does that change your plan?
- Cortical venous reflux carries a risk of parenchymal haemorrhage that is independent of ocular symptoms, so the lesion moves from elective observation to prompt treatment. The plan also changes intraprocedurally, because heparinisation is moderated and the fistulous point must be closed before any outflow is sacrificed.
- You are coiling transvenously and the shunt is only partly closed, but the patient's proptosis worsens acutely on the table. What has happened and what do you do?
- Posterior outflow has been occluded while arterial inflow persists, so arterialised blood has been diverted anteriorly into the superior ophthalmic vein. The correct response is to continue and complete closure of the fistulous point rather than to stop, because stopping leaves the orbit exposed to the full shunt pressure.
- Why is the inferior petrosal sinus still attempted when it fails to opacify on the venous phase?
- Angiographic non-opacification usually reflects chronic thrombosis or diversion of flow rather than obliteration of the channel, and the sinus remains navigable with a wire and microcatheter in a large proportion of such cases. Abandoning the route on the venous run alone forfeits the safest and most direct access.
- Which arterial anatomy must you exclude before injecting liquid embolic into a middle meningeal artery feeder, and why?
- An ophthalmic artery arising from the middle meningeal artery, and dangerous anastomoses between the internal maxillary or ascending pharyngeal arteries and the internal carotid or vertebral circulations. Injecting without excluding these risks central retinal artery occlusion with blindness, or reflux into the cerebral circulation with stroke.
- You have completed coiling and the ipsilateral internal carotid run shows no cavernous filling. Is the case finished?
- No. The endpoint requires external carotid and, where relevant, contralateral and vertebral injections through the full venous phase, because indirect fistulae are frequently supplied from multiple territories. A single ipsilateral run can appear clean while an external carotid feeder continues to shunt.
- A young man with a traumatic direct fistula has a pseudoaneurysm at the tear. Why does this alter your technique?
- Coils placed into an unsupported pseudoaneurysm cavity will prolapse into the carotid lumen and embolise distally. A compliant balloon inflated across the defect or a covered stent is used to stabilise the framing coil and protect the carotid lumen during deployment.
- Why is the sixth nerve the one most often affected after transvenous coiling, and what does that tell the patient about prognosis?
- The abducens nerve travels freely within the cavernous sinus rather than in its lateral wall, so it is directly exposed to the coil mass. The palsy is usually a compressive and transient phenomenon and the majority recover over weeks to months, which allows conservative management with orthoptic support.
- When is internal carotid artery sacrifice acceptable in a direct fistula, and what must precede it?
- It is a last resort when the fistula cannot be closed with carotid preservation and the shunt threatens vision or life. It must be preceded by balloon test occlusion demonstrating adequate cross-flow and clinical tolerance, because sacrifice without this assessment risks a large territorial infarct.
- A patient presents at 14 hours from last known well with an M1 occlusion, NIHSS 14, prestroke mRS 0, age 74, ASPECTS 4. Your centre has no CT perfusion. Do you treat?
- Yes. The 2026 AHA/ASA guideline gives a COR 1 recommendation for selected patients aged under 80 with internal carotid artery or M1 occlusion at 6-24 hours, NIHSS 6 or more, prestroke mRS 0-1 and ASPECTS 3-5, without significant mass effect. Selection is expressed in ASPECTS, so the absence of perfusion imaging does not exclude this patient; the requirement is that there is no significant mass effect on the non-contrast CT.
- You have deployed a 6 mm stent retriever across an internal carotid terminus clot and achieve mTICI 3, but the patient wakes with a dense contralateral hemiplegia far worse than baseline. What has happened anatomically?
- Most likely occlusion or avulsion of the anterior choroidal artery, which arises from the supraclinoid internal carotid artery just proximal to the terminus and supplies the posterior limb of the internal capsule. It has no meaningful collateral supply, so a small perforator infarct there produces a dense hemiplegia despite complete large-vessel reperfusion.
- Why is direct contact aspiration suggested as the first-line strategy in basilar artery occlusion rather than a stent retriever?
- The ESO-ESMINT basilar guideline suggests aspiration first-line based on limited evidence. Mechanistically, the basilar trunk gives off numerous small pontine perforators with no collateral supply, and dragging a stent retriever along that surface risks shearing or occluding them; aspiration at the clot face avoids traversing and abrading the perforator-bearing segment.
- Mid-procedure, a test injection through the microcatheter shows contrast extravasating into the subarachnoid space. What is your first action, and what must you not do?
- Inflate the balloon guide catheter to arrest inflow and reverse heparin with protamine, while leaving the microcatheter in place. The critical error is withdrawing the microcatheter, because it may be tamponading the perforation; if bleeding continues, the same microcatheter is used to coil or embolise the perforated branch.
- After a successful thrombectomy with mTICI 3, the ward asks you for a blood pressure target and suggests keeping systolic below 140 mmHg. What is your answer and why?
- Decline it. In anterior circulation large vessel occlusion successfully recanalised to mTICI 2b, 2c or 3, an intensive systolic target below 140 mmHg for the first 72 hours carries a COR 3 Harm designation. Reperfused brain has impaired autoregulation and lowering pressure aggressively risks extending infarction in marginally perfused tissue.
- A patient has an M3 occlusion with NIHSS 4. The referring physician asks for thrombectomy. What do you say?
- Decline routine thrombectomy. DISTAL and ESCAPE-MeVO, both published in 2025, were neutral for medium and distal vessel occlusion, with numerically higher symptomatic intracranial haemorrhage, stroke progression and recurrent stroke in the thrombectomy arms. There is no evidence base supporting a benefit that would justify the added procedural risk in a mild deficit.
- What does an mTICI grade of 2b actually mean, and why is 2c or 3 preferred as an endpoint?
- mTICI 2b denotes antegrade reperfusion of more than half the previously occluded target territory. It is the accepted minimum threshold for technical success, but 2c and 3 represent near-complete and complete reperfusion respectively, and greater extent of reperfusion correlates with better functional outcome, so 2b is the point at which further passes stop being clearly beneficial rather than the point of an optimal result.
- You find a fetal posterior cerebral artery on the diagnostic run in a patient with an internal carotid terminus occlusion. How does this change your assessment of the final result?
- The occipital lobe is supplied from the internal carotid artery rather than the basilar artery, so the target territory includes the posterior cerebral artery distribution. A final run showing restored middle and anterior cerebral artery flow but a persistently unfilled fetal posterior cerebral artery is not a complete result, and grading it as mTICI 3 would be wrong.
- What is the gold-standard investigation for a suspected spinal vascular malformation?
- Selective catheter spinal DSA is the reference standard. MRI and time-resolved MRA or CTA can suggest and localize a lesion, but DSA best defines the feeder, shunt point or nidus, normal cord supply and venous drainage.
- What constitutes a complete spinal angiogram?
- It is a clinically appropriate bilateral selective examination of all potential arterial contributors, including vertebral and cervical branches, intercostal, lumbar, internal iliac or lateral sacral and median sacral arteries as required. Every injection must be technically adequate, correctly level-labeled and recorded through the relevant venous phase.
- Why must both sides be injected at each relevant level?
- The spinal cord and its venous system are midline structures, and the feeding artery may arise contralateral to the dominant MRI abnormality. Unilateral sampling can therefore miss a dural or perimedullary shunt.
- What is the artery of Adamkiewicz?
- It is the great anterior radiculomedullary artery, usually left-sided and arising in the lower thoracic or upper lumbar region, which provides a major contribution to the anterior spinal artery. Its origin is variable and must be identified before treating a segmental pedicle.
- How do you describe a spinal dural arteriovenous fistula angiographically?
- State the exact vertebral level and side, the radiculomeningeal arterial feeder, the shunt at the dural nerve-root sleeve, early drainage into a radicular vein and the direction and extent of congested perimedullary venous drainage. Also document any normal radiculomedullary artery arising from the same pedicle.
- Why can spinal angiography be falsely negative?
- Correctable causes include failure to inject the lesion-bearing territory, technically inadequate selective injection, wrong level labeling, incomplete venous-phase acquisition and failure to recognize a lesion already visible on the images. High clinical suspicion should trigger a completeness and interpretation audit.
- What is the most feared complication and how is it prevented?
- Spinal cord infarction with permanent neurologic deficit is the most feared complication. Prevention includes gentle air-free catheter technique, avoidance of wedged or forceful injections, recognition of normal cord supply, maintenance of perfusion and minimizing catheter trauma and thromboembolism.
- When is radial access useful?
- Radial access is a feasible alternative for selected targeted or thoracolumbar studies and when femoral or aortoiliac anatomy is unfavorable. The operator must ensure that catheter length, support and access geometry allow every required vessel to be examined.