Posterior Cerebral Artery-to-Superior Cerebellar Artery Side-to-Side Bypass via Extreme Lateral Supracerebellar Infratentorial Approach: Technical Note.

BACKGROUND: Difficult-to-treat aneurysms of the distal posterior cerebral artery (PCA) can often be treated by parent artery occlusion. A cerebrovascular bypass can complement PCA occlusion to curb the risk of ischemic complications. An in situ bypass may be considered when the occipital artery or superficial temporal artery cannot serve as a bypass donor. This article describes the use of a side-to-side bypass of superior cerebellar artery as a donor to the PCA via an extreme lateral supracerebellar infratentorial approach (ELSCIT). This bypass approach can be a useful surgical strategy for PCA revascularization. METHODS: A 40-year-old woman underwent a side-to-side PCA-superior cerebellar artery bypass via the ELSCIT approach for to treat a complex and previously coiled PCA aneurysm. The bypass was followed by endovascular aneurysm and parent artery occlusion. RESULTS: Postoperatively, the patient experienced transient, partial trochlear nerve palsy of the left eye without ischemic lesions on magnetic resonance imaging. The clinical condition was stable, and angiography showed a patent bypass and complete aneurysm occlusion 12 months after surgery. CONCLUSIONS: The ELSCIT approach offers access to the medial and distal PCA that is suitable for a side-to-side PCA-superior cerebellar artery bypass. This type of approach and bypass may be of value when revascularization of a P2-P3 portion of the PCA is needed, but a suitable occipital artery or superficial temporal artery is not available.

Can angiographic Flat Detector Computed Tomography blood volume measurement be used to predict final infarct size in acute ischemic stroke?

INTRODUCTION AND PURPOSE: Flat detector computed tomography (FD-CT) technology is becoming more widely available in the angiography suites of comprehensive stroke centers. In patients with acute ischemic stroke (AIS), who are referred for endovascular therapy (EVT), FD-CT generates cerebral pooled blood volume (PBV) maps, which might help in predicting the final infarct area. We retrospectively analyzed pre- and post-recanalization therapy quantitative PBV measurements in both the infarcted and hypoperfused brain areas of AIS patients referred for EVT. MATERIALS AND METHODS: We included AIS patients with large vessel occlusion in the anterior circulation referred for EVT from primary stroke centers to our comprehensive stroke center. The pre- and post-recanalization FD-CT regional relative PBV (rPBV) values were measured between ipsilateral lesional and contralateral non-lesional areas based on final infarct area on post EVT follow-up cross-sectional imaging. Statistical analysis was performed to identify differences in PBV values between infarcted and non-infarcted, recanalized brain areas. RESULTS: We included 20 AIS patients. Mean age was 63 years (ranging from 36 to 86 years). The mean pre- EVT rPBV value was 0.57 (±0.40) for infarcted areas and 0.75 (±0.43) for hypoperfusion areas. The mean differences (Δ) between pre- and post-EVT rPBV values for infarcted and hypoperfused areas were respectively 0.69 (±0.59) and 0.69 (±0.90). We found no significant differences (p > 0.05) between pre-EVT rPBV and ΔrPBV values of infarct areas and hypoperfusion areas. CONCLUSION: Angiographic PBV mapping is useful for the detection of cerebral perfusion deficits, especially in combination with the fill run images. However, we were not able to distinguish irreversibly infarcted tissue from potentially salvageable, hypoperfused brain tissue based on quantitative PBV measurement in AIS patients.

Flat Detector CT with Cerebral Pooled Blood Volume Perfusion in the Angiography Suite: From Diagnostics to Treatment Monitoring.

C-arm flat-panel detector computed tomographic (CT) imaging in the angiography suite increasingly plays an important part during interventional neuroradiological procedures. In addition to conventional angiographic imaging of blood vessels, flat detector CT (FD CT) imaging allows simultaneous 3D visualization of parenchymal and vascular structures of the brain. Next to imaging of anatomical structures, it is also possible to perform FD CT perfusion imaging of the brain by means of cerebral blood volume (CBV) or pooled blood volume (PBV) mapping during steady state contrast administration. This enables more adequate decision making during interventional neuroradiological procedures, based on real-time insights into brain perfusion on the spot, obviating time consuming and often difficult transportation of the (anesthetized) patient to conventional cross-sectional imaging modalities. In this paper we review the literature about the nature of FD CT PBV mapping in patients and demonstrate its current use for diagnosis and treatment monitoring in interventional neuroradiology.

Selective Angiographic Flat Detector Computer Tomography Blood Volume Imaging in Pre-Operative Vascular Mapping and Embolization of Hypervascular Intracranial Tumors-Preliminary Clinical Experience.

Pre-operative embolization of hypervascular intracranial tumors can be performed to reduce bleeding complications during resection. Accurate vascular mapping of the tumor is necessary for both the correct indication setting for embolization and for the evaluation of the performed embolization. We prospectively examined the role of whole brain and selective parenchymal blood volume (PBV) flat detector computer tomography perfusion (FD CTP) imaging in pre-operative angiographic mapping and embolization of patients with hypervascular intracranial tumors. Whole brain FD CTP imaging with a contrast injection from the aortic root and selective contrast injection in the dural feeding arteries was performed in five patients referred for tumor resection. Regional relative PBV values were obtained pre- and post-embolization. Total tumor volumes with selective external carotid artery (ECA) supply volumes and post-embolization devascularized tumor volumes were determined as well. In all patients, including four females and one male, with a mean age of 54.2 years (range 44-64 years), the PBV scans were performed without adverse events. The average ECA supply was 54% (range 31.5-91%). The mean embolized tumor volume was 56.5% (range 25-94%). Relative PBV values decreased from 5.75 ± 1.55 before embolization to 2.43 ± 1.70 post-embolization. In one patient, embolization was not performed because of being considered not beneficial for the resection. Angiographic FD CTP imaging of the brain tumor allows 3D identification and quantification of individual tumor feeder arteries. Furthermore, the technique enables monitoring of the efficacy of pre-operative endovascular tumor embolization.

Extreme Lateral Supracerebellar Infratentorial Approach (ELSCIT) for Occipital Artery-to-Posterior Cerebral Artery Bypass: Results in 3 Cases.

OBJECTIVE/BACKGROUND: The need for revascularization of the distal posterior cerebral artery (PCA) in the treatment of PCA aneurysms is a contentious issue. Approaches to the PCA, such as the subtemporal route, carry significant perioperative risk. This risk at times outweighs the risk of ischemia associated with endovascular PCA sacrifice. This paper describes the use of an extreme lateral supracerebellar infratentorial (ELSCIT) approach as an alternative technique for distal PCA revascularization. METHODS: Between 2016 and 2019, 3 patients underwent a PCA bypass via the ELSCIT approach for the treatment of a PCA aneurysm. In all cases, an end-to-side anastomosis to the P2- or P3-segment of the PCA was made, with the occipital artery as a donor. Bypass procedures were followed by endovascular parent artery occlusion, without ischemic complications. RESULTS: In all 3 cases, the ELSCIT approach offered a broad enough surgical corridor to perform an occipital artery-to-PCA bypass. One patient suffered a cerebrospinal fluid leak that was surgically treated. Patients' clinical conditions were stable on follow-up (mean follow-up of 34 months). All 3 aneurysms remained occluded, and no ischemia was detected on magnetic resonance imaging. CONCLUSIONS: The ELSCIT approach offers an alternative route to the distal PCA for extracranial-to-intracranial bypass with seemingly low perioperative morbidity and good surgical access to the PCA.

Vessel territory mapping after cerebral revascularization surgery using selective angiographic flat detector perfusion imaging.

The technical feasibility and diagnostic potential of angiographic flat-detector perfusion imaging technique, combining digital subtraction angiography with a flat-detector computed tomography steady-state perfusion imaging, was explored in patients treated with direct or indirect revascularization surgery. This short communication is about an imaging modality with great potential for evaluation, comparison and grading of vascular perfusion territory areas and anatomical location selectively perfused by direct and indirect cerebral bypasses.

Multicenter, retrospective analysis of endovascular treatment for acute ischemic stroke in nonagenarians.

BACKGROUND: With the increasing age of acute stroke patients being admitted to hospitals, more data are needed on indications, complications and outcome of endovascular treatment (EVT) in the very elderly. METHODS: Retrospective observational study with data collection from Belgian, Swiss, Canadian comprehensive stroke centers and Swedish EVT National database. All patients with acute ischemic stroke were eligible if aged older than or ≥90 years and treated with EVT ± pretreatment with intravenous thrombolysis (IVT). Safety assessment comprised presence of periprocedural complications, hemorrhagic transformation or other adverse events (<7days). Efficacy and outcome measures were successful recanalization (modified Treatment In Cerebral Infarction (mTICI) score ≥2b), favorable clinical outcome (modified Rankin Score (mRS) 0-2) and 3-months mortality. RESULTS: Inclusion of 112 nonagenarians (mean age 93.3 ± 2.5 years; 76.8% women; pre-mRS ≤2 in 69.4%). Pretreatment with IVT was performed in 54.7%. In 74.6% successful recanalization (mTICI ≥2b) was achieved. Favorable outcome (mRS ≤2) was seen in 16.4% and 3-months mortality was 62.3%. Multivariate logistic regression analysis showed younger age (odds ratio [OR] 2.99; 1.29-6.95; P = .011) and lower prestroke mRS (OR 13.46; 2.32-78.30; P = .004) as significant predictors for good clinical outcome at 90 days. CONCLUSIONS: Our observational study on EVT in nonagenarians demonstrates the need for careful patient selection. A substantial proportion of nonagenarians shows an unfavorable clinical outcome and high mortality, despite acceptable recanalization rates. A high prestroke disability (mRS) and advancing age predict an unfavorable outcome. Treatment decisions should be made on case-by-case evaluation, keeping in mind limited chances of favorable outcome and high risk of mortality.

Geniculate Artery Embolization in Patients With Recurrent Hemarthrosis After Knee Arthroplasty: A Retrospective Study.

BACKGROUND: Recurrent hemarthrosis after knee arthroplasty is an uncommon and disabling complication of this frequently performed procedure. Selective endovascular embolization of the geniculate arteries is one of the therapeutic options to manage this complication. The purpose of this study is to analyze the effectiveness of this treatment in patients suffering from recurrent hemarthrosis after knee arthroplasty. METHODS: We performed a retrospective study of 31 patients (39 embolization procedures) with recurrent hemarthrosis after knee arthroplasty. There were 17 men and 14 women with a median age of 67 years (range 48-90). All patients were referred for geniculate artery embolization between January 2007 and November 2016. RESULTS: Twenty-seven procedures were executed on the right side and 12 on the left side. Total knee arthroplasty was performed on 29 patients, only 2 patients underwent unicompartmental knee arthroplasty. Embolization of the superior geniculate arteries was achieved in all patients. In 12 of 39 procedures (31%), at least 1 of the inferior geniculate arteries could not be catheterized, therefore embolization was achieved through collaterals. Symptomatic improvement was observed in 26 of 31 patients (84%). Discomfort or mild postprocedural pain was observed in most patients, needing only minor pain medication, mostly resolving within 24 hours. Two patients presented with a severe complication: a 48-year-old male patient developed septic arthritis and an 85-year-old hypertensive female patient treated with anticoagulants showed aseptic necrosis of the femoral condyles. CONCLUSION: Embolization of geniculate arteries is a safe and effective treatment in recurrent hemarthrosis post knee arthroplasty. Clinical improvement was seen in most patients.

Complete Transection of Optic Nerve After Endovascular Coiling of a Large Ophthalmic Artery Aneurysm.

BACKGROUND: We describe a patient who developed delayed blindness of the left eye at 5 weeks after endovascular coiling of a large ophthalmic aneurysm. CASE DESCRIPTION: A 44-year-old male was admitted with visual decline due to compression of the optic nerve by a large ophthalmic aneurysm. The aneurysm was treated by endovascular coiling, but visual function was unchanged. One month and 7 days later, the patient developed sudden blindness of the affected eye, despite complete angiographical occlusion of the aneurysm. Surgical exploration in an attempt to restore vision showed a fully thrombosed aneurysm but, surprisingly, complete transection of the optic nerve just proximal to its entry into the optic canal. CONCLUSIONS: This report describes a rare complication of a sudden increase in size of a large ophthalmic aneurysm despite successful endovascular occlusion.

Current concepts in imaging and endovascular treatment of acute ischemic stroke: implications for the clinician.

During the last decade, the management of acute ischemic stroke has changed dramatically, from an expectant bedside "wait and see" attitude towards active treatment, thanks to the continuous improvement of new therapeutic options. In addition to the use of intravenous (IV) thrombolysis in emergent large vessel occlusion (ELVO), endovascular therapy (EVT) has proven to be very efficient in selected acute stroke patients. The indications for EVT have progressed from the era of thrombolysis to individual patient profiling. Recently, several indication parameters, e.g., "treatment time window" or "more distal vessel occlusion," are under debate for adjustment. In this article, we review the imaging strategies in acute stroke and discuss several EVT indication dogmas, which are subject to change.

Frequency-place map for electrical stimulation in cochlear implants: Change over time.

The relationship between the place of electrical stimulation from a cochlear implant and the corresponding perceived pitch remains uncertain. Previous studies have estimated what the pitch corresponding to a particular location should be. However, perceptual verification is difficult because a subject needs both a cochlear implant and sufficient residual hearing to reliably compare electric and acoustic pitches. Additional complications can arise from the possibility that the pitch corresponding to an electrode may change as the auditory system adapts to a sound processor. In the following experiment, five subjects with normal or near-to-normal hearing in one ear and a cochlear implant with a long electrode array in the other ear were studied. Pitch matches were made between single electrode pulse trains and acoustic tones before activation of the speech processor to gain an estimate of the pitch provided by electrical stimulation at a given insertion angle without the influence of exposure to a sound processor. The pitch matches were repeated after 1, 3, 6, and 12 months of experience with the sound processor to evaluate the effect of adaptation over time. Pre-activation pitch matches were lower than would be estimated by a spiral ganglion pitch map. Deviations were largest for stimulation below 240° degrees and smallest above 480°. With experience, pitch matches shifted towards the frequency-to-electrode allocation. However, no statistically significant pitch shifts were observed over time. The likely explanation for the lack of pitch change is that the frequency-to-electrode allocations for the long electrode arrays were already similar to the pre-activation pitch matches. Minimal place pitch shifts over time suggest a minimal amount of perceptual remapping needed for the integration of electric and acoustic stimuli, which may contribute to shorter times to asymptotic performance.

A spinal arteriovenous fistula in a 3-year old boy.

We present a case of a 3-year-old boy with neurodegeneration. Family history reveals Rendu-Osler-Weber disease. Magnetic resonance imaging (MRI) of the spinal cord and spinal angiography showed a spinal arteriovenous fistula with venous aneurysm, causing compression of the lumbar spinal cord. Embolisation of the fistula was executed, resulting in clinical improvement. A week after discharge he was readmitted with neurologic regression. A second MRI scan revealed an intraspinal epidural haematoma and increase in size of the aneurysm with several new arterial feeders leading to it. Coiling of the aneurysm and fistulas was performed. Postoperative, the spinal oedema increased despite corticoids, causing more extensive paraplegia of the lower limbs and a deterioration of his mental state. A laminectomy was performed and the aneurysm was surgically removed. Subsequently, the boy recovered gradually. A new MRI scan after two months showed less oedema and a split, partly affected spinal chord. This case shows the importance of excluding possible arteriovenous malformations in a child presenting with progressive neurodegeneration. In particular when there is a family history for Rendu-Osler-Weber disease, scans should be performed instantly to rule out this possibility. The case also highlights the possibility of good recovery of paraplegia in paediatric Rendu-Osler-Weber patients.

Electric-acoustic pitch comparisons in single-sided-deaf cochlear implant users: frequency-place functions and rate pitch.

Eight cochlear implant users with near-normal hearing in their non-implanted ear compared pitch percepts for pulsatile electric and acoustic pure-tone stimuli presented to the two ears. Six subjects were implanted with a 31-mm MED-EL FLEX(SOFT) electrode, and two with a 24-mm medium (M) electrode, with insertion angles of the most apical contacts ranging from 565° to 758°. In the first experiment, frequency-place functions were derived from pure-tone matches to 1500-pps unmodulated pulse trains presented to individual electrodes and compared to Greenwood's frequency position map along the organ of Corti. While the overall median downward shift of the obtained frequency-place functions (-0.16 octaves re. Greenwood) and the mean shifts in the basal (<240°; -0.33 octaves) and middle (-0.35 octaves) regions were statistically significant, the shift in the apical region (>480°; 0.26 octaves) was not. Standard deviations of frequency-place functions were approximately half an octave at electrode insertion angles below 480°, increasing to an octave at higher angular locations while individual functions were gradually leveling off. In a second experiment, subjects matched the rates of unmodulated pulse trains presented to individual electrodes in the apical half of the array to low-frequency pure tones between 100 Hz and 450 Hz. The aim was to investigate the influence of electrode place on the salience of temporal pitch cues, for coding strategies that present temporal fine structure information via rate modulations on select apical channels. Most subjects achieved reliable matches to tone frequencies from 100 Hz to 300 Hz only on electrodes at angular insertion depths beyond 360°, while rate-matches to 450-Hz tones were primarily achieved on electrodes at shallower insertion angles. Only for electrodes in the second turn the average slopes of rate-pitch functions did not differ significantly from the pure-tone references, suggesting their use for the encoding of within-channel fine frequency information via rate modulations in temporal fine structure stimulation strategies.

Brain stones revisited-between a rock and a hard place.

OBJECTIVES AND METHODS: Large intracranial calcifications are occasionally encountered in routine computed tomography (CT) scans of the brain. These calcifications, also known as "brain stones", can be classified according to location and aetiology. Combining imaging findings with relevant clinical history and physical examination can help narrow down the differential diagnosis and may allow confident diagnosis in certain situations. RESULTS: This article provides a pictorial review illustrating various clinical entities resulting in brain stones. DISCUSSION: Based on location, brain stones can be classified as extra- or intra-axial. Extra-axial brain stones comprise tumours and exaggerated physiological calcifications. Intra-axial brain stones can further be classified according to aetiology, namely neoplastic, vascular, infectious, congenital and endocrine/metabolic. Imaging findings combined with essential clinical information can help in narrowing the differential diagnosis, determining disease state and evaluating effect of therapy. TEACHING POINTS: • Based on location, brain stones can be either extra- or intra-axial. • Extra-axial brain stones comprise tumours and exaggerated physiological calcifications. • Intra-axial aetiologies include neoplastic, vascular, infectious, congenital and endocrine/metabolic. • CT scan is the mainstay in identifying and characterising brain stones. • Certain MRI sequences (gradient echo T2* and susceptibility-weighted imaging) are considered adjunctive.

Perforated oculomotor nerve after endovascular coiling: complete regeneration after microsurgical repair. case report.

BACKGROUND AND IMPORTANCE: We describe a patient who developed complete right oculomotor nerve palsy after endovascular coiling for a ruptured posterior communicating artery aneurysm caused by migration of the coils outside the aneurysm. CLINICAL PRESENTATION: A 50-year-old woman was admitted with an acute subarachnoid hemorrhage. She underwent, on the day of admission, endovascular coiling of a ruptured posterior communicating artery aneurysm. Four hours postcoiling, complete right oculomotor nerve palsy developed because of extrusion of the coils outside the aneurysm. The patient recovered completely after surgical exploration with removal of the migrated coils and microsurgical repair of the oculomotor nerve. CONCLUSION: This report illustrates that oculomotor nerve palsy is a rare complication after coiling of a posterior communicating artery aneurysm, and it should serve as a reminder to encourage neurovascular teams to consider surgical exploration in cases of third nerve palsy after endovascular coiling.

Microsurgical removal of Onyx HD-500 from an aneurysm for relief of brainstem compression. Case report.

The authors report the successful removal of Onyx HD-500 from an aneurysm sac by means of ultrasonic aspiration. This 46-year-old woman presented with progressive spasms of her left arm and leg due to mass effect and compression on the right cerebral peduncle 5 years after endovascular treatment of an unruptured giant posterior communicating artery aneurysm with Onyx HD-500. No filling of the aneurysm was detected on angiography. The patient underwent a right pterional craniotomy and the aneurysm was opened to remove the Onyx mass. However, contrary to expectations, the aneurysm was still patent, filling with blood between the Onyx mass and the aneurysm wall. Under temporary clipping of the carotid artery, the Onyx mass within the aneurysm was removed in a piecemeal fashion using an ultrasonic aspirator and the aneurysm was then successfully clipped. The patient experienced significant improvement of the spasm after surgery. Angiography showed complete occlusion of the posterior communicating artery aneurysm. It is rarely necessary to remove embolization material such as Onyx HD-500, and little is known about the most appropriate surgical technique. This case report demonstrates that removal can be safely accomplished by means of ultrasonic aspiration.

Imaging findings in pyogenic ventriculitis.

INTRODUCTION: Pyogenic ventriculitis is an uncommon but often severe intracranial infection. METHODS: Case report with illustrative CT and MRI imaging. RESULTS: A 49-year-old man presented with an intraparenchymal hematoma with extension of blood into the ventricles. The persistence of intraventricular blood necessitated long term placement of an external ventricular drain. On day 23 after admission, a contrast-enhanced CT scan of the brain showed slight hydrocephalus, irregular debris in the dependent part of the occipital horns and periventricular hypodensities. An MRI scan confirmed the characteristic hallmarks of pyogenic ventriculitis on the T2-weighted, Fluid Attenuated Inversion Recovery (FLAIR), and diffusion-weighted and contrast-enhanced T1-weighted images. CONCLUSION: Neuroimaging is crucial in clearly depicting pyogenic ventriculitis. A contrast-enhanced CT scan, but especially MR imaging, is an ideal tool to reliably diagnose this life-threatening cerebral infection.