Sphenoparietal Sinus Transposition: Operative Technique for Optimizing Pretemporal Posterior Circulation Access While Preserving the Sylvian Venous Complex

BACKGROUND

Transsylvian approaches are a cornerstone of complex cranial operations, with wide applicability across cerebrovascular, skull base, and neuro-oncology operations. Deep lesions, especially those involving the basilar apex, midbrain, or interpeduncular fossa, require wide exposures that may be inhibited by the presence of a large complex of superficial sylvian veins (SSV) draining into the sphenoparietal sinus. This report describes technical and clinical aspects of the sphenoparietal sinus transposition (SPST) technique.

METHODS

Technical case report of the SPST technique, including a step-by-step neuroanatomic description, overview of common indications, clinical pearls and pitfalls, and illustrative case examples.

RESULTS

Once the benefits of proceeding with SPST have been established, the maneuver is initiated with 2 stepwise dural incisions: an incision from lateral to medial along the lateral margin of the lesser sphenoid wing, followed by an orthogonal cut across the temporal pole down the middle fossa floor. The pretemporal dura is peeled off the lateral wall of the cavernous sinus, allowing mobilization of the SSV complex and temporal pole posteriorly without disrupting or straining the connection point at the sphenoparietal sinus. Illustrative case examples include a clip reconstruction of a basilar apex aneurysm for which earlier endovascular treatment had failed and microsurgical resection of a peduncular cavernous malformation.

CONCLUSIONS

SPST is a simple but versatile technique with important applications in complex cranial surgery. By mobilizing the SSV complex together with its dural attachment, the transsylvian corridor can be markedly widened, allowing access to the basilar apex region and ventral midbrain.

A meta-analysis and systematic review of endovascular thrombectomy versus medical management for acute basilar artery occlusion

OBJECTIVE

Acute basilar artery occlusion (BAO) is a devastating neurologic event. As endovascular thrombectomy (EVT) became more prevalent for anterior circulation strokes, investigations were conducted in the posterior circulation. Its success in improving outcomes compared to standard medical therapy (SMT) after BAO has been debated.

METHODS

We conducted a systematic review and meta-analysis of all randomized controlled trials (RCTs) and observational cohort studies evaluating EVT compared to SMT in acute BAO. We queried PubMed, Embase, and Cochrane for studies. Primary outcome was good functional outcome at 90 days (modified Rankin scale (mRS) ≤ 3). We analyzed studies for risk of bias (ROB) and calculated pooled risk ratios (RRs), odds ratios (ORs), and mean differences (MDs) with 95% confidence intervals (95%CI) using the random effects model for our primary outcome and secondary positive outcomes and harms.

RESULTS

We identified four RCTs (991 patients randomized) and three cohort studies (1030 patients treated in-trial) that fit inclusion criteria. Three RCTs had low ROB, one had serious ROB. One cohort study had high ROB, one had moderate ROB, and one had low ROB. EVT was statistically significantly more associated with good functional outcome than SMT in RCTs (RR=1.54, 95%CI=1.16-2.04, p = 0.003) and trended towards significance in cohort studies (RR=2.64, 95%CI=0.87-8.00, p = 0.09). Mean mRS at 90 days was lower in EVT patients in RCTs (MD=-0.65, 95%CI=-1.07--0.22, p = 0.003) though not cohort studies (MD =-0.84, 95%CI=-2.48-0.79, p = 0.31). Symptomatic intracerebral hemorrhage (sICH) was statistically significantly associated with EVT in RCTs (OR=6.36, 95%CI=2.24-18.07, p < 0.001) and statistically non-significantly in cohort studies (OR=4.51, 95CI=1.00-20.33, p = 0.05). Mortality at 90 days was statistically lower with EVT than with SMT in both RCTs (OR=0.76, 95%CI=0.65-0.88, p < 0.001) cohort studies (OR=0.36, 95%CI=0.26-0.50, p < 0.001) CONCLUSION: EVT is associated with greater rates of good functional outcomes and lower rates of death and disability despite higher rates of periprocedural sICH.

Revascularization of a Complex Case of Vertebrobasilar Insufficiency with Occipital Artery-Anterior Inferior Cerebellar Artery Bypass

Atherosclerotic disease is the most common etiology in causing posterior circulation strokes and can be found within the intracranial vertebrobasilar system.¹ Endovascular and surgical approaches to treat this disease have been defined with both advantages and disadvantages.^2,3 We present a case of surgical revascularization of a complex case of vertebrobasilar insufficiency with occipital artery (OA)-anterior inferior cerebellar artery (AICA) bypass (Video 1). A 56-year-old gentleman presented with severe, disabling, and progressive symptoms of vertebrobasilar insufficiency refractory to maximal medical management. Symptom onset was 2 years prior after suffering a left lateral medullary stroke due to a left vertebral artery (VA) occlusion. Angiography showed left VA occlusion after the origin of the posterior inferior cerebellar artery (PICA) and a hypoplastic right VA mostly ending in a PICA with a small and critically stenosed branch to the basilar artery. An initial attempt to revascularize the chronic totally occluded left VA using a combination of anterograde and retrograde (via PComm) approaches was unsuccessful. The decision was made to proceed with an OA-AICA bypass. The end-to-side anastomosis was conducted in the right cerebellopontine cistern and was uncomplicated. Postoperative angiography demonstrated a patent bypass with brisk OA-to-AICA flow with retrograde filling of the basilar artery and its branches. No perioperative strokes. The patient remained free of recurrent symptoms of vertebrobasilar insufficiency at 6 months' follow-up.

Horizontal stent deployment via extracranial-intracranial bypass in coil embolization of basilar apex aneurysms: technical report

BACKGROUND

The endovascular treatment of large, wide-necked basilar apex aneurysms (BAAs) remains challenging. Although horizontal stent deployment across both P1 segments of the posterior cerebral arteries (PCAs) would be an optimal strategy in coil embolization of wide-necked BAAs, this is only feasible in cases with anatomically favorable access. In rare circumstances, large-diameter conduits of extracranial-intracranial (EC-IC) bypass can also provide a good access route for endovascular treatment of complex intracranial aneurysms.

METHODS

We describe the technique of accessing the PCA via EC-IC bypass grafts and deploying a stent horizontally across the neck of BAA and its coil embolization. We provide a detailed technical review and describe some pitfalls of the procedure.

RESULTS

Two patients underwent EC-IC bypass surgery prior to the treatment of a large, wide-necked BAA. The radial artery and saphenous vein were used as grafts, respectively. To facilitate coil embolization for a large BAA, a PCA-to-PCA horizontal stent was deployed via the bypass graft. Trans-cell and jailing techniques were used, respectively. Both aneurysms were completely occluded, and the patients were discharged without any neurological deficit.

CONCLUSION

Horizontal stent deployment via EC-IC bypass grafts can be performed safely, providing proper closure of the aneurysmal neck and apposition to both PCAs, facilitating complete coil embolization.

Posterior Circulation Stroke: Coma (More Than Time) is Brain

BACKGROUND AND PURPOSE

Contrary to anterior circulation, the legitimacy of endovascular treatment in posterior circulation stroke is still being questioned. Finding reliable prognostic factors and determining how patient selection should be done has become top priority.

METHODS

Observational and retrospective study from two Portuguese hospitals, including all consecutive patients with posterior circulation occlusions who underwent thrombectomy between January 1st 2015 and December 31st 2019.

RESULTS

Out of a total of 126 patients, the median age was 74 (IQR 61-80) and 39.7% were female. A good clinical outcome (mRS ≤2) was associated with a lower incidence of coma (24,2% vs 66,7%, p < 0,001) and of sudden onset coma (3% vs 18%,=0,04), a lower NIHSS at admission (14 vs 19, p < 0,001), a higher pc-ASPECTS at admission (10 vs 9, p < 0,001) and at 24 h (8 vs 6, p < 0,001) and a higher BATMAN score (7 vs 6, p = 0,017). Differences in the times of symptom-onset-to-recanalization (496 vs 536, p = 0,19) and symptom-onset-to-coma (130 vs 195, p = 0,52) were not remarkable. When excluding NIHSS and pc-ASPECTS at 24 h, coma (p = 0,003; OR=0,22; 95% CI: 0,08-0,59) and the pc-ASPECTS at admission (p = 0,037; OR=1,63; 95% CI: 1,03-2,57) become independent predictors of good outcome.

CONCLUSIONS

In strokes from the posterior circulation, coma, more than time, appears to be an important prognostic factor. The BATMAN and the pc-ASPECTS scores were also associated with clinical outcome and coma.

Persistent Stapedial Artery Resulting in Direct Communication Between the Middle Meningeal and Basilar Arteries: Clinical Image

A persistent stapedial artery originates from the petrous segment of the internal carotid artery due to failure of the regression of the embryonic stapedial artery. During embryologic development, the stapedial artery supplies the middle meningeal artery through the ventral pharyngeal artery. The presence of a persistent stapedial artery can result in direct communication between the basilar and middle meningeal arteries. We present a cerebral angiogram image of an adult patient that shows a right-sided persistent stapedial artery with communication between the right middle meningeal and basilar arteries. It is important to recognize such rare anatomic variants during endovascular interventions to avoid catastrophic complications such as nontarget embolization of the posterior circulation.

Distal Basilar Artery "Umbrella Aneurysm" Treated by Radial Artery Graft Bypass From the External Carotid Artery to Posterior Cerebral Artery and Clip Trapping: 2-Dimensional Operative Video

A 71-yr-old woman was discovered to have an incidental distal basilar artery (BA) fusiform aneurysm 7 × 5 mm in dimension, shaped like an "umbrella handle" with critical stenosis distal to the aneurysm. The right posterior cerebral artery (PCA) P1 segment was small; the left posterior communicating artery (PComA) was miniscule. Because the natural history of fusiform BA aneurysms is poorly defined, this was equated to a saccular aneurysm, with an estimated 10-yr rupture rate of 29%.1-8 After discussion of alternative treatments, the patient decided upon surgery. Because of inadequate collateral circulation, a bypass to the left PCA was deemed necessary.  The aneurysm was exposed by an extended trans-sylvian approach, and the left PCA P2 segment was visualized subtemporally. The left radial artery (RAG) was extracted, and pressure distended to prevent vasospasm. The RAG bypass was sutured first to the P2, and then to the cervical external carotid artery (ECA); the BA aneurysm was then clipped. The proximal anastomosis of the bypass needed revision because of poor flow; a 4-mm punch hole was made to widen the arteriotomy on the ECA. The patient was discharged home with mild memory loss and partial left cranial nerve III palsy. After discharge, she developed a severe left hemicrania, resolved with gabapentin. At 6-wk follow-up, she was asymptomatic, and computed tomography (CT) angiogram demonstrated patency of the bypass.  The patient gave informed consent for surgery and video recording. All relevant patient identifiers have been removed from the video and accompanying radiology slides.

Direct Vertebral Artery Access for Coil Embolization of a Partially Thrombosed Mid-Basilar Trunk Aneurysm: Technical Limitations

BACKGROUND AND IMPORTANCE

Partially thrombosed basilar aneurysms have a high morbidity from the rupture risk and mass effect prompting early treatment. Depending on the size and location, they pose a surgical challenge often requiring multiple endovascular treatment modalities. Here we present a partially thrombosed mid-basilar aneurysm successfully coil embolized with direct vertebral artery access and discuss the technical limitations of direct V1 access.

CLINICAL PRESENTATION

A 70-yr-old woman presented with acute onset headache, nausea, and vomiting. A computed tomography (CT) head demonstrated a hyperdense prepontine mass which was further characterized as a partially thrombosed basilar aneurysm on CT angiography. After multiple failed attempts to access the vertebral artery via femoral and radial access the patient was taken to the operating room (OR) for surgical exposure of the right V1 segment and direct cannulation of the vertebral artery. The aneurysm was successfully coiled and the vertebral artery closed primarily. The patient was discharged home without any neurological deficits.

CONCLUSION

Partially thrombosed mid-basilar aneurysms are difficult to treat both surgically and endovascularly. We present a case where endovascular access to the aneurysm was very challenging requiring direct exposure and cannulation of the V1 segment to successfully embolize with coils and discuss the technical limitations of this approach.

Dementia resulting from expansion of basilar artery aneurysm: two case reports and a review of the literature

BACKGROUND

Dementia places a large burden on the economy, with financial and emotional costs incurred by patients, caregivers and the health sector.

METHODS AND RESULTS

We report the first published case series of giant basilar aneurysm leading to progressive cognitive and functional decline. We review the literature regarding giant aneurysms and their association with dementia and the possible underlying pathophysiological mechanism.

CONCLUSIONS

This report highlights a number of therapeutic considerations when determining the best management strategy for these difficult lesions.