Angiographic and embryologic considerations in five cases of middle cerebral artery fenestration

Five cases of unilateral middle cerebral artery fenestration were observed during the prospective evaluation of 1466 consecutive cerebral angiograms (0.43% of 1170 patients) between January 1999 and July 2001. In each case, an early branching temporopolar artery was seen to arise from the inferior limb of the fenestrated segment. This finding suggests that early branching temporopolar arteries may participate in the formation of middle cerebral artery fenestration by interfering with the normal fetal development of the middle cerebral artery.

Tailored cognitive testing with provocative amobarbital injection preceding AVM embolization

BACKGROUND AND PURPOSE

Transarterial embolization of cerebral arteriovenous malformations (AVMs) has been associated with postprocedural neurologic complications in 7-39% of patients. We sought to determine whether a method of targeted neurologic and cognitive testing during AVM embolization reduces the incidence of focal cognitive and other neurologic deficits associated with the procedure.

METHODS

A cognitive neurologist extensively examined 12 patients prior to AVM embolization. In each patient, a battery of tests tailored to their specific abilities was developed by using stimuli selected from standard and experimental cognitive tests to probe specific brain regions related to the location of the AVM. In each feeder vessel to be embolized, a 50-mg bolus of sodium amobarbital was superselectively administered through a microcatheter; this was followed immediately by neurologic and cognitive testing with the tailored battery. After testing, the position of the microcatheter tip was checked with fluoroscopy. If the provocative test results were negative, the evaluated feeder was embolized with N-butyl cyanoacrylate glue.

RESULTS

Although results with 27 of 29 provocative amobarbital injections were negative, results with two injections in two different individuals revealed cognitive deficits during tailored provocative testing. In both, the evoked deficits resolved with dissipation of the amobarbital effect; the feeder vessels were not embolized. Neurologic and cognitive evaluation after each of 27 embolizations revealed no major or minor deficits.

CONCLUSION

In our experience, provocative amobarbital testing prior to AVM embolization was helpful in identifying vascular territories where embolization may lead to neurologic and cognitive deficits.

Bilateral arch origin of the vertebral arteries

A case of bilateral anomalous origins of the vertebral arteries (VAs) is reported. Both VAs arose directly from the aortic arch between the left common carotid artery and the left subclavian artery. The possible embryologic mechanism and clinical importance of this previously unreported variant are reviewed.

CT findings in the infantile form of citrullinemia

Citrullinemia is a rare autosomal recessive inborn error of the urea cycle due to a deficiency in argininosuccinic acid synthetase. We present two cases of the infantile form of citrullinemia in which CT revealed bilateral and symmetric corticosubcortical hypoattenuating areas, ulegyric changes, and atrophy in the frontal lobes, as well as atrophy in the gyrus cinguli, insulae, and temporal lobes.

Pooling of echographic contrast agents during transcranial Doppler sonography: a sign in favor of slow-flowing giant saccular aneurysms

Transcranial Doppler (TCD) sonography is a new imaging technique allowing for non-invasive evaluation of the intracranial vascular anatomy and cerebral hemodynamics. The recent introduction of echographic contrast agents has significantly increased the sensitivity of TCD for the diagnosis of intracranial vascular lesions. We report a case of giant AComA aneurysm, undetected by color and power TCD, which became visible after echographic contrast administration as a delayed and persistent area of contrast enhancement. Knowledge of atypical or contrast-specific lesion appearances will become important if contrast-enhanced TCD is to be used routinely in the diagnosis of intracranial aneurysms.

Training and pretreatment planning of interventional neuroradiology procedures--initial clinical validation

A PC based system for simulating image-guided interventional neuroradiological procedures for physician training and patient specific pretreatment planning is described. The system allows physicians to manipulate and interface interventional devices such as catheters, guidewires, stents and coils within 2-D and hybrid surface and volume rendered 3-D patient vascular images in real time. A finite element method is employed to model the interaction of the catheters and guidewires with the vascular system. Fluoroscopic, roadmapping and volume rendered 3-D presentations of the vasculature are provided. System software libraries allow for the use of commonly employed catheters, guidewires, stents and occluding coils of various shapes and sizes. The results of an initial clinical validation suggest that the experience gained from our simulator is comparable with that of using a vascular phantom. We are conducting further validation with the aim of providing patient specific pretreatment planning.

Vascular compression by a ventricular shunt catheter: clinical value of volume-rendered CT angiography

One of the strongest advantages of CT angiography (CTA) lies in its unique ability to display simultaneously the anatomy of the vascular system and the topographic relationships existing between the vessels and the neighboring structures. The case we report, a 76-year-old man who underwent an intraventricular shunt placement complicated by a stroke, shows how this topographic assessment also provides important diagnostic information when vascular lesions resulting from an extrinsic compression mechanism are suspected.

In vitro evaluation of the effectiveness of distal protection in the prevention of cerebral thromboembolism during carotid stent placement

RATIONALE AND OBJECTIVES

The purpose of this in vitro study was to evaluate and quantify the benefit of the balloon protection device, to identify the most effective sequence of irrigation or flushing, and to determine the most effective catheter position to remove the maximum number of emboli or debris beneath the flow-arrest balloon.

MATERIALS AND METHODS

Silicone models of the neurovasculature were attached to a systodiastolic pump. Stents were placed in carotid stenoses by using the distal flow protection technique. Embolic material was released within the stent. The effectiveness of different irrigation techniques was evaluated.

RESULTS

Aspiration under the balloon through the guiding catheter with a 60-mL syringe followed by one power injection at 40 mL injected at 2 mL/sec will result in removal of about 98% of potential emboli from the internal carotid artery [corrected].

CONCLUSION

In vitro evaluation of the distal flow protection technique indicates that it should reduce stroke risk during carotid stent placement.

Role of the distal balloon protection technique in the prevention of cerebral embolic events during carotid stent placement

BACKGROUND AND PURPOSE

We sought to quantitatively and qualitatively evaluate the release of atheromatous plaque debris induced by carotid stenting procedures.

METHODS

Eight patients with severe carotid atheromatous stenoses were treated by stent implantation under distal balloon protection. Blood samplings were obtained after stent deployment in the blood pooled below the inflated protection balloon. The samples were centrifuged and evaluated for plaque debris with the use of light microscopy. The debris release was quantitatively estimated by dividing the total volume of debris obtained by the mean debris size. Five patients without endovascular procedure were used as a control group.

RESULTS

The 2 main debris types found were nonrefringent cholesterol crystals (4 to 389 microm; 115 to 8697 in number) and lipoid masses (7 to 600 microm; 341 to 34 000 in number). There was a statistically significant difference compared with the samples obtained in the control group (P:=0.017).

CONCLUSIONS

Blood samples collected during stent implantation procedures contain a large quantity of atheromatous plaque debris. This emphasizes the role of distal protection techniques in avoiding migration of this plaque material into the cerebral circulation.

Anatomic relationship between arachnoid granulations in the transverse sinus and the termination of the vein of Labbé: an angiographic study

We studied the anatomic relationship between arachnoid granulations in the transverse sinus and the termination of the vein of Labbé in 57 consecutive angiograms. Patients with pathology in intracranial venous structures or with inadequate image quality of the venous system were excluded. Arachnoid granulations were found in 12 of the 57 patients (21.1%), always at the junction of the vein of Labbé and the transverse sinus; the vein of Labbé was present in 55 patients (96.5%), most often without associated arachnoid granulations; the latter, however, were not observed in the absence of a vein of Labbé. This study confirms the close, constant anatomic relationship between arachnoid granulations in the transverse sinus and the termination of the vein of Labbé. This observation may help to differentiate arachnoid granulations from pathologic conditions involving the transverse sinus such as dural sinus thrombosis. The constant character of this relationship suggests a developmental role of afferent veins in the formation of arachnoid granulations.

Endovascular treatment of cerebral aneurysms: An in vitro study with detachable platinum coils and tricellulose acetate polymer

OBJECTIVE

The purpose of our experimental study was to determine the effectiveness of filling the cavity of in vitro aneurysms with detachable platinum coils and the combination of detachable platinum coils and liquid embolic agent.

MATERIALS AND METHODS

Silicone aneurysm models were connected to a circulatory system to simulate arterial flow. A microcatheter was used to introduce detachable coils into the aneurysm cavities. First, platinum coils were introduced until the point of minimal dense packing, indicated by aneurysmal circulatory exclusion. Packing was continued up to maximal dense packing, indicated by protrusion of the coil into the parent artery. Volumetric ratios (coil volume-aneurysm volume) were calculated for minimal and maximal dense packing. Then, after purposeful undercoiling of aneurysm models, a micropump system was used to fill the aneurysm by stepwise injection of tricellulose acetate polymer through the coil mesh until angiographic aneurysm exclusion was completed. The volumetric ratios of maximal packing with coils and tricellulose acetate polymer in relation to the aneurysm volume were calculated.

RESULTS

Maximal dense packing ratios with coils (mean, 32.5%; standard deviation [SD], 3%) were slightly higher than those with the minimal dense packing (mean, 28. 2%; SD, 3%) but were always less than 37%. The ratios of packing with the combined use of coils and tricellulose acetate polymer were greater than 100% (mean, 124.4%; SD, 15%).

CONCLUSION

Knowledge of the volumetric ratio of maximal dense packing was useful for effective filling with coils and tricellulose acetate polymer. The combined use of coils and liquid polymer appeared more effective than the use of coils alone for the complete occlusion of the aneurysm lumen.

Neurovascular embolization: in vitro evaluation of a mechanical detachable platinum coil system

The authors evaluated a mechanically detachable platinum coil system intended for neurovascular use. The introduction characteristics, ease of delivery, ease of retrieval, and detachability were studied with fluoroscopic guidance with in vitro silicone models. All the coils passed easily through the microcatheter. The detachment maneuver occurred within 20 seconds with 20 or fewer rotations of the pusher wire. One of 229 coils detached prematurely but only after deliberate and extreme manipulation. The detachment system is safe, reliable, and consistent and will be useful for interventional neuroradiologists.

Angiographic anatomy of the laterocavernous sinus

BACKGROUND AND PURPOSE

The laterocavernous sinus (LCS) has recently been recognized as one of the major drainage pathways of the superficial middle cerebral vein (SMCV). Our purpose was to investigate the drainage pattern of the SMCV, with special emphasis on the angiographic anatomy of the LCS.

METHODS

The drainage pathways of the SMCV were evaluated prospectively on 100 selective carotid angiograms obtained in 65 consecutive patients.

RESULTS

The SMCV was absent in 19% of cases. A classic termination into the cavernous sinus (CS) was found in 20%, a paracavernous sinus in 39%, and an LCS in 22%. The LCS drained toward the pterygoid plexus (27%), the superior petrosal sinus (18%), the posterior aspect of the CS (32%), or a combination of these pathways (23%). A complete absence of connection between the LCS and CS was observed in 63.5% of the patients.

CONCLUSION

The LCS is a laterosellar venous space that is anatomically and angiographically distinct from the CS. Secondary small anastomoses between the LCS and CS may make it difficult to differentiate the two structures. Appreciation of the course and connection pattern of the LCS is important, particularly when planning an endovascular approach to treatment of lesions in the region of the CS.

Liver of the "visible man"

Endoscopic surgery, also called minimally invasive surgery, is presumed drastically to reduce postoperative morbidity and thus to offer both human and economic benefits. For the surgeon, however, this approach leads to a number of gestural challenges that require extensive training to be mastered. In order to replace experimentation on animals and patients, we developed a simulator for endoscopic surgery. To achieve this goal, a first step was to develop a working prototype, a "standard patient," on which the informatic and microengineering tools could be validated. We used the visible man dataset for this purpose. The external shape of the visible man's liver, his biliary passages, and his extrahepatic portal system turned out to be fully within the standard pattern of normal anatomy. Anatomic variations were observed in the intrahepatic right portal vein, the hepatic veins, and the arterial blood supply to the liver. Thus, the visible man dataset reveals itself to be well suited for the simulation of minimally invasive surgical operation such as endoscopic cholecystectomy.

Termination of the inferior petrosal sinus: an anatomical variant

Unusual caudal terminations of the inferior petrosal sinus (IPS) characterized by an extracranial extension joining the internal jugular vein up to 40 mm below the external skull base are reported. This variation was observed bilaterally on an anatomical specimen and unilaterally on four patients during diagnostic cerebral angiography. It may be considered an accessory internal jugular vein and, if present, may allow for an alternate endovascular access to the IPS.

Anatomy teaching for medical undergraduates: general practice as a guideline? The brain

Basic science teaching, particularly the teaching of gross anatomy, is at present a highly controversial topic. How much and what kind of anatomy should be taught to medical undergraduates nowadays? In conducting the present study we based our proposals on the criterion of general medical relevance. Therefore, we sent an anatomical questionnaire to a sample of Swiss general practitioners. Here, we present the results derived from questions on the human brain, discussing them in connection with the other organs so far investigated. The results obtained suggest that a common body of anatomical knowledge appropriate for the field of general medical practice does in fact exist. We believe that this basic stock can serve as a guideline for decision makers involved in the development of curricula, which can be fitted into the time frame available for anatomy teaching today while still guaranteeing a sound level of competence required for general practice of medicine. We also hope that this approach may serve as a model for the teaching of other basic sciences.

Contrast-enhanced MR angiography: the effects of k-space truncation on luminal representation in a carotid artery phantom model

Using carotid bifurcation phantom models with different degrees of stenoses, we evaluated the accuracy of vessel lumen representation on MR images obtained from the inverse Fourier transform of different k-space percentages. Our results show that the lower thresholds of truncated k-space sampling are dictated by the severity of luminal narrowing. The defined thresholds may help improve efficiency of 3D MR imaging of the carotid arteries while maintaining adequate luminal representation.