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.

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.

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.

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.

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.

Navigation with three-dimensional rotational radiographic data for transpedicular percutaneous needle introduction: feasibility and comparison with fluoroscopic guidance.

PURPOSE: To investigate the feasibility of navigation with three-dimensional (3D) rotational radiographic data for transpedicular percutaneous needle introduction and to compare navigation with 3D rotational radiographic data with conventional fluoroscopic guidance. MATERIALS AND METHODS: A navigation system was coupled to a 3D rotational radiographic imaging system. In a cadaver study, 60 biopsy needles were introduced into vertebral bodies with fluoroscopic guidance or navigation with 3D rotational radiographic data by two interventionalists with different levels of experience in percutaneous procedures. Radiation exposure, fluoroscopy and introduction times, and needle position were evaluated and compared. RESULTS: For 3D rotational radiographic navigation, the needle position was equivalent for both interventionalists (7 mm). For fluoroscopic guidance, the interventionalist with less experience in percutaneous procedures had significantly more pedicle cortex violations than the other interventionalist (eight vs one). Radiation exposure measured at the operators' hand was lower for 3D rotational radiography-guided needle introductions. Radiation exposure measured at the body wall of the cadaver was equivalent between modalities (9 mGy). CONCLUSIONS: Navigation with 3D rotational radiographic image data is feasible for transpedicular percutaneous needle introduction and has two advantages compared with fluoroscopic guidance: it poses less strict requirements on the expertise of the interventionalist, and it reduces radiation exposure to the interventionalist.

Three-dimensional rotational X-ray navigation for needle guidance in percutaneous vertebroplasty: an accuracy study.

STUDY DESIGN: The position of a needle tip displayed on a navigation system after transpedicular introduction into a vertebral body is compared with the real position of the needle tip when using a direct navigation coupling between a three-dimensional rotational X-ray (3DRX) system and a navigation system. OBJECTIVES: To assess whether the needle tip position displayed by the navigation system corresponds to the real needle position and to quantitatively determine needle navigation accuracy in a clinically relevant setting. SUMMARY OF BACKGROUND DATA: Image-guided navigation has reportedly increased the accuracy and safety of pedicle screw insertion and decreased complication rates. In former studies, the result of image-guided navigation was mainly compared qualitatively with the result of conventional fluoroscopy-guided procedures. Previously, a direct navigation coupling between a 3DRX system and a standard navigation system was introduced that bypasses the need for explicit patient-to-image registration necessary for image-guided orthopedic surgery. In a phantom experiment, the reported accuracy of navigation with the coupling to a 3DRX system was approximately 1 mm. However, in a clinical setting, additional errors can be introduced. METHODS: Twenty-three needles were placed transpedicularly into vertebral bodies of embalmed human trunks using 3DRX-guided navigation. The navigated needle tip positions were compared with the real needle tip positions manually extracted from 3DRX volumes acquired after completion of the introduction. RESULTS: The average distance between the navigated needle tip and the real position of the needle tip extracted from a postprocedure 3DRX volume was 2.5 +/- 1.5 mm. CONCLUSIONS: Accuracy of 3DRX-guided navigation is 2.5 +/- 1.5 mm in a clinically relevant setting, which is less than the accuracy determined in phantom experiments.

The risk of new osteoporotic vertebral compression fractures in the year after percutaneous vertebroplasty.

PURPOSE: To prospectively assess the incidence, location, and possible causative mechanisms of new vertebral compression fractures (VCFs) in 66 symptomatic patients with osteoporotic VCFs treated with percutaneous vertebroplasty (PV) and to study the relation between new VCFs and back pain symptoms. MATERIALS AND METHODS: Sixty-six patients with 102 painful symptomatic VCFs were treated with PV. All patients had baseline total spinal magnetic resonance (MR) imaging. Follow-up MR imaging was performed at 3, 6, and 12 months to locate new VCFs. Visual analog scales for pain and pain medication consumption were used to assess clinical outcomes. The following characteristics were compared in patients with new VCFs after PV versus patients without new VCFs: patient age, sex, presence of secondary osteoporosis, bone mineral density, number of preexisting VCFs, shape and grade of VCFs, type of bone cement used for PV, volume of injected cement, and cement leakage in intervertebral disc spaces. RESULTS: Sixteen of 66 patients had 26 new VCFs during 1 year of follow-up after PV. Most new VCFs occurred within 3 months of PV, half of new VCFs appeared in levels adjacent to treated levels, and half of the new VCFs were symptomatic. The presence of more than two preexisting VCFs was the only independent risk factor for the development of a new VCF. CONCLUSIONS: New VCFs occurred after PV in 24% of patients. Half of new VCFs occurred in levels adjacent to treated levels and half were symptomatic. The presence of more than two preexisting VCFs was the only independent risk factor for the development of a new VCF.