Subcortical cystic lesions within the anterior superior temporal gyrus: a newly recognized characteristic location for dilated perivascular spaces

SUMMARY

Cystic parenchymal lesions may pose an important diagnostic challenge, particularly when encountered in unexpected locations. Dilated perivascular spaces, which may mimic cystic neoplasms, are known to occur in the inferior basal ganglia and mesencephalothalamic regions; a focal preference within the subcortical white matter has not been reported. This series describes 15 cases of patients with cystic lesions within the subcortical white matter of the anterior superior temporal lobe, which followed a CSF signal; were located adjacent to a subarachnoid space; demonstrated variable surrounding signal change; and, in those that were followed up, showed stability. Pathology study results obtained in 1 patient demonstrated chronic gliosis surrounding innumerable dilated perivascular spaces. These findings suggest that dilated perivascular spaces may exhibit a regional preference for the subcortical white matter of the anterior superior temporal lobe. Other features-lack of clinical symptoms, proximity to the subarachnoid space, identification of an adjacent vessel, and stability with time-may help in confidently making the prospective diagnosis of a dilated perivascular space, thereby preventing unnecessary invasive management.

Long-term clinical and imaging follow-up of complex intracranial aneurysms treated by endovascular parent vessel occlusion

BACKGROUND AND PURPOSE

Flow-diverting stents are increasingly being used for the treatment of complex intracranial aneurysms, but the indications for their use in lieu of traditional endovascular PVO have yet to be precisely defined. The purpose of this study was to review the clinical and imaging outcomes of patients with intracranial aneurysms treated by PVO.

MATERIALS AND METHODS

A total of 28 patients with intracranial aneurysms, treated by PVO between July 1992 and December 2009, were reviewed. Aneurysms arising from peripheral arteries were excluded. Clinical and imaging data were retrospectively analyzed from a prospectively maintained data base.

RESULTS

There were 28 patients with 28 aneurysms treated by PVO. Aneurysms of the anterior circulation presenting with mass effect (n = 11) or discovered incidentally (n = 1), and dissecting-type VB aneurysms presenting with subarachnoid hemorrhage (n = 6) faired the best with high obliteration rates (83.3% and 83.6%, respectively) and no permanent major ischemic complications. In contrast, VB aneurysms presenting with mass effect (n = 7) demonstrated the lowest obliteration rate (57.1%), the highest rate of permanent major ischemic complications (28.6%), and a high mortality rate (28.6%).

CONCLUSIONS

PVO is a safe and effective treatment for complex intracranial aneurysms of the carotid artery and dissecting-type VB aneurysms presenting with SAH. In contrast, PVO for aneurysms of the VB circulation presenting with mass effect is less efficacious and associated with significant morbidity and mortality. It is hoped that flow diverters may represent a better treatment technique for these most difficult-to-treat lesions.

Canadian experience with the pipeline embolization device for repair of unruptured intracranial aneurysms

BACKGROUND AND PURPOSE

Flow-diverting stents, such as the PED, have emerged as a novel means of treating complex intracranial aneurysms. This retrospective analysis of the initial Canadian experience provides insight into technical challenges, clinical and radiographic outcomes, and complication rates after the use of flow-diverting stents for unruptured aneurysms.

MATERIALS AND METHODS

Cases were compiled from 7 Canadian centers between July 2008 and December 2010. Each center prospectively tracked their initial experience; these data were retrospectively updated and pooled for analysis.

RESULTS

During the defined study period, 97 cases of unruptured aneurysm were treated with the PED, with successful stent deployment in 94 cases. The overall complete or near-complete occlusion rate was 83%, with a median follow-up at 1.25 years (range 0.25-2.5 years). Progressive occlusion was witnessed over time, with complete or near-complete occlusion in 65% of aneurysms followed through 6 months, and 90% of aneurysms followed through 1 year. Multivariate analysis found previous aneurysm treatment and female sex predictive of persistent aneurysm filling. Most patients were stable or improved (88%), with the most favorable outcomes observed in patients with cavernous carotid aneurysms. The overall mortality rate was 6%. Postprocedural aneurysm hemorrhage occurred in 3 patients (3%), while ipsilateral distal territory hemorrhage was observed in 4 patients (3.4%).

CONCLUSIONS

Flow-diverting stents represent an important tool in the treatment of complex intracranial aneurysms. The relative efficacy and morbidity of this treatment must be considered in the context of available alternate interventions.

Recanalization rates after endovascular coil embolization in a cohort of matched ruptured and unruptured cerebral aneurysms

The aim of this study was to retrospectively assess the recanalization rate, factors associated with and time taken for recanalization to occur in a matched ruptured and unruptured aneurysm population that were treated with endovascular coiling.Ruptured and unruptured aneurysms treated between 2002 and 2007 were matched for aneurysm location, diameter and neck size. Recanalization rate, time to recanalize, re-treatment rate and clinical outcome were analysed. Ninety-eight matched ruptured and unruptured aneurysms (49 aneurysms in each group) were studied. 46.8% of aneurysms in the ruptured group achieved complete obliteration on the initial post treatment angiogram versus 34.7% in the unruptured group. The ruptured group had a higher rate of recanalization (40.4% versus 20.4%). 25.5% of aneurysms had significant recanalization in the ruptured group versus 6.1% in the unruptured group (p=0.009). The retreatment rate was higher in the ruptured group (21.3% versus 6%). Ruptured aneurysms took a shorter time to recanalize with a mean time of 5.3±3.8 months versus 12.4±7.7months (p=0.003). Multivariate logistic regression analysis found neck size (p=0.0098), wide neck morphology (p=0.0174), aneurysm diameter (p< 0.0001) and ruptured aneurysms (p=0.0372) were significant predictors of recanalization. The majority of patients in both groups had a good outcome with GOS=5 (85.7% and 83.7%) but two deaths occurred in the ruptured group.Ruptured and unruptured aneurysms showed significant differences in rate, degree and timing of recanalization, thus requiring different protocols for imaging follow-up post endovascular treatment. Earlier and more frequent imaging follow-up is recommended for ruptured aneurysms.

Negative CT angiography findings in patients with spontaneous subarachnoid hemorrhage: When is digital subtraction angiography still needed?

BACKGROUND AND PURPOSE

CTA is becoming the frontline modality to reveal aneurysms in patients with SAH. However, in about 20% of SAH patients no aneurysm is found. In these cases, intra-arterial DSA is still performed. Our aim was to evaluate whether negative findings on CTA can reliably exclude aneurysms in patients with acute SAH.

MATERIALS AND METHODS

We conducted a retrospective analysis of all negative findings on CTAs performed from 2005 to 2009 in patients with spontaneous SAH. Findings were compared with DSA. CTAs were performed with a 64-section multidetector row CT scanner.

RESULTS

One hundred ninety-three patients with SAH and negative findings on CTA who underwent subsequent DSA were identified. The distribution of blood on unenhanced CT was the following: PMH in 93 patients, diffuse aneurysmal pattern in 50, no blood on CT (xanthochromic LP) in 32, and peripheral sulcal distribution in 18. All patients with PMH had negative findings on DSA. One patient with no blood on CT had vasculitis on DSA. Six of 18 (33%) patients with peripheral blood had vasculitis on DSA. Three of these were also diagnosed by CTA. All except 1 patient with diffuse aneurysmal blood had negative findings on DSA. One patient was diagnosed with an aneurysm on DSA (1/50, 0.5%). Repeat delayed DSA performed in 28 of these patients revealed a small aneurysm in 4 (14%). Five patients had a complication of DSA (2.6%); 1 was a clinical stroke (0.5%).

CONCLUSIONS

In patients with SAH, negative CTA findings are reliable in ruling out aneurysms in the PMH pattern or no blood on CT. DSA is indicated in the diffuse aneurysmal pattern of SAH, and repeat delayed DSA is required if the initial DSA findings are negative. When the blood is peripheral, CTA should be scrutinized for vasculitis and DSA is recommended for confirmation.

Cranial dural arteriovenous fistula: diagnosis and classification with time-resolved MR angiography at 3T

BACKGROUND AND PURPOSE

The diagnosis of dural arteriovenous fistula (DAVF) remains one of the few uncontested indications for catheter based cerebral angiography. We report our experience of using a commercially available form of time-resolved MR angiography (trMRA) at 3T for the diagnosis and classification of a cranial DAVF compared with the reference standard of digital subtraction angiography (DSA).

MATERIALS AND METHODS

A retrospective review of our patient records identified patients who had undergone trMRA at 3T and DSA for the evaluation of DAVF. The trMRA consisted of whole-head, contrast-enhanced "time-resolved imaging of contrast kinetics" (TRICKS) MRA. Image sets were independently reviewed by 3 readers for the presence, location, and classification of a DAVF. The reported result of the DSA was used as the gold standard against which the performance of the trMRA was measured.

RESULTS

Forty patients were identified who had undergone DSA and trMRA for evaluation of DAVF, yielding a total of 42 cases. On DSA, the results of 7 cases were normal, 15 cases were performed for surveillance of a previously cured fistula, and a new fistula (14) or persistent (6) fistula was found in 20 cases. Of these 20 fistulas, on DSA, 13 were Borden I, 2 were Borden II, and 5 were Borden III. In 93% (39/42) of DAVF cases, the 3 readers were unanimous and correct in their independent interpretation of the trMRA, correctly identifying (or excluding) all fistulas and accurately classifying them when encountered.

CONCLUSIONS

In this small series, trMRA at 3T seems be a reliable technique in the screening and surveillance of DAVF in specific clinical situations.

Management and clinical outcome of posterior fossa arteriovenous malformations: report on a single-centre 15-year experience

OBJECTIVES

Posterior fossa brain arteriovenous malformations (PFbAVMs) are rare lesions. Management is complicated by eloquence of adjacent neurological structures, multimodality treatment is often necessary, and obliteration is not always possible. We describe a 15-year experience in the management of posterior fossa brain AVMs with a focus on clinical outcome.

METHODS

From 1989 to 2004, prospectively collected information on 106 patients with diagnosis of a PFbAVMs was obtained. Clinical and angioarchitectural characteristics, management options and complications are described and reviewed to evaluate their impact on final outcome as measured by the Modified Rankin Score (mRS).

RESULTS

Ninety-eight patients were followed for an average of 3.3 years (1-14.6). The male-to-female ratio was 1:1. Ninety-five out of 98 patients (96.9%) were symptomatic at presentation, with 61 (62.2%) intracranial haemorrhages. Sixty-two patients were treated (46 cerebellar, 16 brainstem). Ten haemorrhages occurred in follow-up (4.1%/year). The mRS was obtained in 62 patients and was classified as low (good, mRS<or=2) or high (poor, mRS>or=3). Haemorrhage was the only predictor of poor mRS at presentation (p = 0.0229). A poor clinical outcome was correlated with the presence of AA (p = 0.0276), a poor initial mRS (p<0.0001) and the number of treatments needed (p = 0.0434). Patients were significantly more likely to improve than to deteriorate over time (p = 0.0201).

CONCLUSION

The final clinical outcome in PFbAVMs relates directly with the presence of associated aneurysms, number of treatments needed to obliterate the AVM and mRS at presentation. Despite the fact that patients tend to improve after brain AVM haemorrhage, the relationship of MRS at presentation and final outcome suggests that an expedited, more definitive treatment is probably a better choice, especially in patients with good grades after the initial bleeding.

Clinical and angiographic follow-up of ruptured intracranial aneurysms treated with endovascular embolization

BACKGROUND AND PURPOSE

Endovascular embolization is a well-established treatment of ruptured intracranial aneurysms, but concern about its long-term stability and its ability to prevent rehemorrhage are still present. We evaluated the long-term clinical and angiographic follow-up of patients with ruptured cerebral aneurysms treated with coiling, focusing on rehemorrhage and changes in aneurysm morphologic features.

MATERIALS AND METHODS

A total of 377 patients with ruptured aneurysms that were treated with endovascular approaches at our institution between 1994 and 2008 were reviewed. Clinical and angiographic data were analyzed from a prospectively collected data base.

RESULTS

There were 377 patients with 391 ruptured aneurysms treated for 14 years. Good outcome (Glasgow Outcome Score [GOS], 5) was achieved in 74% of patients, moderate disability or poor outcome in 18%, and 8.8% died. Permanent morbidity or mortality from procedural complications occurred in 2.9%. Complete follow-up was available for 85% of surviving patients, with mean follow-up of 22.3 months. Re-treatment was required in 11% (31 patients). Eight (2.1%) patients had rebleeding, 6 (1.6%) in the hospital within 30 days of treatment, 5 in the first 48 hours. Follow-up imaging was available in 276 aneurysms in 270 patients. Recanalization occurred in 56 of 276 aneurysms (20.3%) regardless of the initial angiographic result, but the risk was higher if a body remnant was left (chi2, 11.791; P = .0006).

CONCLUSIONS

Long-term clinical and angiographic follow-up demonstrates the efficacy of endovascular treatment of ruptured intracranial aneurysms. Rebleeding after treatment is rare, with the greatest risk during the first 48 hours after treatment. Initial angiographic results are not a useful predictor of clinical outcome or rehemorrhage.

Characterization of aneurysm remnants after endovascular treatment: contrast-enhanced MR angiography versus catheter digital subtraction angiography

BACKGROUND AND PURPOSE

A substantial percentage of coiled aneurysms are associated with persistent filling of an aneurysmal component due to incomplete initial treatment or re-growth. Traditionally follow-up of coiled aneurysms has consisted of repeated intra-arterial cerebral catheter angiography, an invasive procedure with associated risks. Hence, many authors have advocated the use of non-invasive imaging techniques for this purpose. Our aim was to compare contrast-enhanced MR angiography (CE-MRA) with digital subtraction angiography (DSA) for depiction of aneurysmal remnants of coiled cerebral aneurysms.

MATERIALS AND METHODS

Aneurysms coiled between September 2003 and October 2006 were retrospectively reviewed. We included patients meeting the following criteria: 1) residual/recurrent aneurysm measuring 2 mm or greater, and 2) CE-MRA and DSA performed no more than 60 days apart. Three readers were asked to determine which technique was superior for characterization of the aneurysmal remnant: CE-MRA, DSA, or indeterminate. Statistical analysis included most rule and kappa statistics.

RESULTS

Of 232 patients who underwent coiling, 44 met the inclusion criteria (33 women and 11 men; 24-72 years of age). Sixteen patients had neck remnants and 28 had body remnants. The first study to identify the remnant was DSA in 35 patients and CE-MRA in 9. In 32 patients (32/44, 73%), the readers indicated that CE-MRA was superior to DSA for remnant characterization. CE-MRA and DSA were thought to be equivalent in 7 (16%), and DSA was preferred in 3 (7%). Two cases (5%) yielded ambiguous results. Of the 28 body remnants, 22 (78.6%) were characterized by remnant protrusion into the coil mass: In 20 of these (91%), the readers preferred CE-MRA over DSA, and in 2 cases (9%), the techniques were thought to be equivalent.

CONCLUSION

In patients with known aneurysm remnants, CE-MRA is at least equivalent to DSA for characterization of aneurysmal remnants after coiling. Contrast filling within the coil mass was more clearly seen with CE-MRA than with DSA.

Segmental artery exchange technique for stable 4F guiding-catheter positioning in embolization of spinal vascular malformations

For anatomic and technical reasons, it is often difficult to achieve guiding-catheter stability in the segmental arteries during embolization of spinal vascular lesions. We have developed a segmental artery exchange technique using a thin-walled 4F nontapered catheter that is safe and achieves a stable guiding-catheter position. This catheter accommodates both the flow-guided and variable-stiffness microcatheters, allowing selective catheterization and treatment of spinal vascular lesions.

Endovascular treatment of intracranial aneurysms with matrix coils: immediate posttreatment results, clinical outcome and follow-up

INTRODUCTION

Endovascular aneurysm repair with coils has become a safe and effective alternative to surgical clipping. Efforts have been made to create coils that will facilitate aneurysm healing and reduce recurrence. The purpose of this study was to review the safety and durability of our aneurysm treatment using Matrix coils.

METHODS

A total of 39 aneurysms in 38 patients, aged 30 to 77 years, were treated using Matrix coils in 42 procedures. Two procedures were unsuccessful, and 12 were done using only Matrix coils. Aneurysm volume, packing density and percentage length of Matrix coils were calculated. The treatment results, procedural complication rate and clinical outcome were analyzed. Follow-up examinations were available for 34 procedures with a mean follow-up of 4.9 months (maximum 13.5 months).

RESULTS

Angiographic results were similar to those following the use of platinum coils, with complete occlusion or a residual neck in 82.5% of procedures. Six procedures (14%) were complicated with platelet aggregation. Recanalization occurred in 32% of the patients. Nine patients (26%) had major recanalization and were retreated. One patient had a re-bleed 5 months after the treatment resulting in severe disability. The mean packing density of 39.2% in the recanalized aneurysms was similar to that in the nonrecanalized group.

CONCLUSION

In our series, treatment with Matrix coils had a complication rate similar to that reported with platinum coils. However, we had a higher percentage of major recanalizations requiring retreatment. We believe that the absorption of the polymer contributes to the failure of formation of a stable scar within the aneurysm.

Transvenous treatment of cranial dural arteriovenous fistulas with hydrogel coated coils

SUMMARY

Intracranial dural arteriovenous fistulas (DAVF) with cortical venous reflux may become symptomatic due to venous congestion or intracranial hemorrhage. Venous congestion in the orbit can also occur resulting in proptosis, chemosis, double vision and progressive visual loss. The transvenous approach has been used for selective disconnection of the venous drainage to eliminate the venous congestion and future risk of intracranial bleeding and/or neurological deficit. Hydrogel coated coils (Hydro- Coil(R)) expand after contact with blood causing the coils to swell up to five to 11 times a standard 10-system bare platinum coil. Due to this property, HydroCoils could have an advantage over platinum coils in the transvenous approach to embolization of DAVFs. Ten patients with symptomatic cranial DAVF underwent a transvenous embolization using HydroCoils as the only embolic agent or in a combination with bare platinum coils. The patients' characteristics, symptoms, angioarchitecture of the DAVF, treatment, complications and results were analyzed. All the treated DAVFs were disconnected at the end of the procedure. All the patients with orbital symptoms had complete or significant improvement. There were no periprocedural complications. Nine patients had radiological follow-up showing cure. HydroCoils can be used effectively and safely to treat intracranial DAVFs transvenously. The volume expansion of Hydrocoils may have significant advantage over bare platinum coils given the large venous spaces that need to be filled. The use of HydroCoils may decrease the procedure time and consequently reduce the radiation dose to the patient.

Acute subarachnoid hemorrhage: using 64-slice multidetector CT angiography to “triage” patients’ treatment

INTRODUCTION

To evaluate the clinical role of CT angiography (CTA) in patients with acute subarachnoid hemorrhage (SAH) for treatment decision-making.

METHODS

Consecutive patients with acute SAH had CTA using a 64-slice scanner for initial clinical decision-making. Image processing included multiplanar volume reformatted (MPVR) maximum intensity projections (MIP) and 3D volume-rendered reconstructions. CTAs were used for (1) evaluating the cause of SAH, and (2) triaging aneurysm-bearing patients to the more appropriate management, either surgical clipping or endovascular coiling. CTA findings were confirmed by neurosurgical exploration or catheter angiography (digital subtraction angiography, DSA). Successful coiling provided evidence that triaging to endovascular treatment was correct.

RESULTS

Included in the study were 73 patients. CTA findings were confirmed by DSA or neurosurgical operation in 65 patients, and of these 65, 47 had aneurysmal SAH, 3 had vasculitis, 1 had arterial dissection and 14 had no underlying arterial abnormality. The cause of SAH was detected with CTA in 62 out of the 65 patients (95.4%, sensitivity 94%, specificity 100%). CTA revealed the aneurysm in 46 of 47 patients (98%, sensitivity 98%, specificity 100%, positive predictive value 100%, negative predictive value 82.3%), 1 of 3 vasculitides and 1 of 1 dissection. Of the 46 patients with aneurysm, 44 (95.7%) were referred for treatment based on CTA. In 2 patients (2 of 46, 4.4%) CTA was not informative enough to choose treatment requiring DSA. Of the 44 patients, 27 (61.4%) were referred to endovascular treatment and successful coiling was achieved in 25 (25 of 27, 92.6%).

CONCLUSION

CTA using a 64-slice scanner is an accurate tool for detecting and characterizing aneurysms in acute SAH. CTA is useful in the decision process whether to coil or clip an aneurysm.

Idiopathic intracranial hypertension: the validity of cross-sectional neuroimaging signs

The aim of this study was to evaluate the accuracy of previously reported neuroimaging signs in establishing or excluding the diagnosis of idiopathic intracranial hypertension (IIH). In a retrospective study, 30 patients with confirmed IIH and 56 controls were evaluated with brain magnetic resonance imaging. All examinations were evaluated in a blinded fashion by three neuroradiologists for the presence or absence of the 'traditional' signs of IIH: empty sella turcica, deformation of the pituitary, slit-like ventricles, 'tight' subarachnoid spaces, flattening of the posterior globe, protrusion of the optic nerve, enhancement of the optic nerve head, distension of the optic nerve sheath and vertical tortuosity of the optic nerve. Optic nerve protrusion and enhancement, slit-like ventricles and tight cerebrospinal fluid spaces were not significantly associated with IIH (P>0.05). Posterior globe flattening, optic nerve sheath distension, optic nerve tortuosity, pituitary deformity and empty sella turcica were significantly associated with IIH (P<0.05). However, most of these are not helpful in a clinical setting, with the exception of posterior globe flattening. This is the only sign that, if present, strongly suggests the diagnosis of IIH (specificity 100%, 95% CI 93.6% to 100%; sensitivity 43.5%, 95% CI 27.3% to 60.8%; positive likelihood ratio 49.7). The majority of the reported signs for IIH on cross-sectional imaging are not helpful in establishing or excluding the diagnosis of IIH, and are of no value in the clinical setting. Flattening of the posterior aspect of the globe is the only sign that, if present, is suggestive of the diagnosis of IIH.

Targeted compartmental embolization of cavernous sinus dural arteriovenous fistulae using transfemoral medial and lateral facial vein approaches

There are multiple transvenous approaches for treatment of cavernous dural arteriovenous fistulae (DAVF). The choice of a specific route depends on the compartment of the cavernous sinus involved in the fistula and its venous drainage. We used two different facial vein approaches to treat patients with cavernous DAVF draining directly into the anterior compartment of the cavernous sinus and thence to the superior ophthalmic vein. Other transvenous routes to the sinus were not apparent. Embolization was targeted to the involved compartment with preservation of those not embolized. No major post-procedure ophthalmic venous engorgement occurred. We believe that ideal treatment of cavernous DAVF is targeted transvenous coil deposition, which necessitates detailed knowledge of the anatomy of the facial veins and cavernous sinus compartments.

Idiopathic intracranial hypertension: the prevalence and morphology of sinovenous stenosis

OBJECTIVE

To determine the prevalence and nature of sinovenous obstruction in idiopathic intracranial hypertension (IIH) using auto-triggered elliptic-centric-ordered three-dimensional gadolinium-enhanced MR venography (ATECO MRV).

METHODS

In a prospective controlled study, 29 patients with established IIH as well as 59 control patients underwent ATECO MRV. In a randomized blinded fashion, three readers evaluated the images. Using a novel scoring system, each reader graded the degree of stenosis seen in the transverse and sigmoid sinuses of each patient.

RESULTS

There was excellent agreement across the three readers for application of the grading system. Substantial bilateral sinovenous stenoses were seen in 27 of 29 patients with IIH and in only 4 of 59 control patients.

CONCLUSION

Using ATECO MRV and a novel grading system for quantifying sinovenous stenoses, the authors can identify IIH patients with sensitivity and specificity of 93%.

Intracranial arteriovenous malformations: real-time auto-triggered elliptic centric-ordered 3D gadolinium-enhanced MR angiography--initial assessment

Auto-triggered elliptic centric-ordered three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiography was compared with 3D multiple overlapping thin-slab acquisition time-of-flight (TOF) MR angiography in the evaluation of intracranial arteriovenous malformations (AVMs) in 10 patients. Intraarterial digital subtraction angiography (DSA) was the reference standard. Gadolinium-enhanced MR angiograms were found to be equivalent to DSA images in AVM component depiction in 70%--90% of cases and were consistently superior to TOF MR angiograms.

Deep cerebral venous thrombosis: an illustrative case with reversible diencephalic dysfunction

BACKGROUND

Isolated thrombosis of the deep cerebral veins is rare and its diagnosis can be difficult. Mortality is often high and little is known about the long-term prognosis.

CASE REPORT

We report a 24-year-old woman with akinetic mutism and extensive bilateral thalamic lesions. CT and MRI allowed early diagnosis by demonstrating thrombosis within the internal cerebral veins, without the need for angiography. Heparin treatment was used safely despite the presence of thalamic and intraventricular hemorrhage. After five weeks, the patient recovered rapidly and remains well at 18 months. Serial MRI showed dramatic resolution of the imaging abnormalities.

CONCLUSIONS

The clinical features and characteristic neuroimaging appearance of deep cerebral venous thrombosis should be recognized by physicians caring for stroke patients. Deep cerebral venous thrombosis can produce extensive venous congestion and vasogenic edema without early infarction. Excellent clinical recovery is possible even after severe and prolonged neurological deficits.

Angiographic and clinical characteristics of patients with cerebral arteriovenous malformations associated with hereditary hemorrhagic telangiectasia

BACKGROUND AND PURPOSE

Cerebral arteriovenous malformations (AVMs) are occasionally associated with hereditary hemorrhagic telangiectasia (HHT), which is characterized by the presence of multiple mucocutaneous telangiectasia, epistaxis, and familial inheritance. We analyzed the angiographic and clinical characteristics of patients with cerebral AVMs related to HHT.

METHODS

Among 638 patients with cerebral AVMs, we identified 14 patients with HHT. The AVMs were classified as those with nidi of 1 cm or less (micro AVMs), those with nidi between 1 and 3 cm (small AVMs), and those of the fistulous type (arteriovenous fistulas [AVFs]).

RESULTS

A total of 28 AVMs were found; seven of 14 patients had multiple AVMs. The 28 AVMs were categorized as 12 micro AVMs, eight small AVMs, and eight AVFs. All except one micro AVM were asymptomatic, whereas all small AVMs were symptomatic. Three of eight AVFs were asymptomatic. All 28 AVMs were located on the cortex. All micro AVMs and AVFs had single feeders and single draining veins, whereas the small AVMs had multiple feeders in all lesions and single draining veins in six of eight lesions.

CONCLUSION

Multiple, cortical, micro AVMs or AVFs harboring single feeding arteries and single draining veins should raise clinical suspicion of HHT-related AVMs.

Dissecting aneurysms of the posterior cerebral artery: angioarchitecture and a review of the literature

Isolated dissecting aneurysms of the posterior cerebral artery are not as rare as previously reported. Affecting primarily a younger population, this condition can be recognized by angiographic patterns, the most common being a "pearl and string" morphology. We reviewed the literature and present a series of six cases, discussing management strategies.

A simple relationship between radiological arteriovenous malformation hemodynamics and clinical presentation: a prospective, blinded analysis of 31 cases

OBJECT

The authors sought to establish prospectively whether there is a simple relationship between radiological features of brain arteriovenous malformation (AVM) hemodynamics and a patient's clinical presentation.

METHODS

Thirty-one consecutive patients with AVMs underwent cerebral angiography at 3.8 frames/second during each standardized injection of contrast material. Contrast dilution curves were derived from the image sequences by using regions of interest (ROIs) traced on arteries feeding and veins draining the AVM nidus. Angiographic parameters were then analyzed in a blinded fashion. These parameters included the times required to reach the peak contrast density, the contrast decay time, and fractions thereof, in the ROI for each vessel. The authors determined whether these parameters, the arteriovenous transit time, and/or AVM size were related to patients' presentation with hemorrhage (11 patients), seizure (11 patients), or other clinical symptoms (nine patients). Statistically significant results were found only in analyses of arterial phase times to reach peak contrast density. Analyses of venous parameters, AVM size, and nidus transit time showed trends but no statistical significance. Arterial filling with contrast material was significantly slower in patients presenting with hemorrhage (mean 50%, 80%, and 100% of time to peak +/- standard error [SE] = 1.19+/-0.13, 1.97+/-0.18, and 3.04+/-0.34 seconds, respectively) compared with patients presenting with seizures (mean 50%, 80%, and 100% of time to peak +/- SE = 0.80+/-0.12, 1.32+/-0.18, and 1.95+/-0.29 seconds, respectively) according to analysis of variance (p<0.05) and post-hoc t-tests (p<0.05) for each parameter. Patients who presented with other symptoms had intermediate arterial filling times.

CONCLUSIONS

These simple hemodynamic parameters, which can be obtained without added risk to the patient, may help identify a subset of individuals in whom AVMs pose a higher risk of future hemorrhage and who may therefore warrant more expeditious treatment.

Acute human histopathology of an intracranial aneurysm treated using Guglielmi detachable coils: case report and review of the literature

OBJECTIVE AND IMPORTANCE

This case study provided us with the opportunity to explore the histopathological effects of Guglielmi detachable coil (GDC) therapy on the aneurysm orifice and parent vessel-aneurysm neck interface. This type of study is important to the understanding of the mechanisms of obliteration of aneurysms by GDCs.

CLINICAL PRESENTATION

The patient presented with a Hunt and Hess Grade III subarachnoid hemorrhage that occurred secondary to the rupture of a small anterior communicating artery aneurysm.

INTERVENTION

The aneurysm was successfully coiled without complication, but the patient died 36 hours later. We examined the gross and microscopic pathological findings of this GDC-treated anterior communicating artery aneurysm 36 hours after coiling. A discrete membrane composed of fibrin had formed completely across the aneurysm orifice, excluding the aneurysm sac from the circulation. This membrane was contiguous with the parent vessel.

CONCLUSION

This case represents one of the first examples in humans of the formation of a membrane over the aneurysm orifice after GDC therapy. The formation of this membrane, shown to be composed of fibrin, was found at 36 hours after coiling, which is the earliest time frame at which membrane formation has been noted in either humans or animal models. This fibrin membrane may function both as a scaffold for subsequent endothelialization across the aneurysm neck as well as to isolate the aneurysm from the parent circulation, permitting thrombus within the aneurysm sac to mature to an endovascular scar. The factors contributing to the formation of this membrane and its clinical implications are discussed.

Serial magnetic resonance imaging findings for a spontaneously resolving spinal subdural hematoma: case report

OBJECTIVE AND IMPORTANCE

Spinal subdural hematoma (SSDH) is a rare entity, and cases are usually managed as surgical emergencies. We describe a patient with a SSDH who demonstrated incomplete clinical resolution with nonsurgical management, despite continued anticoagulation treatment. We provide the most complete demonstration of the magnetic resonance imaging (MRI) characteristics of a large SSDH from its initiation to its radiological resolution.

CLINICAL PRESENTATION

A 61-year-old woman developed a large SSDH as a complication of a lumbar puncture. Her only neurological deficit was urinary retention.

INTERVENTION

Because of the extensiveness of the hematoma and the relative neurological preservation of the patient, she was treated conservatively. Serial MRI scans were obtained at 4, 7, 13, and 25 days. The evolution of deoxyhemoglobin in the hematoma to methemoglobin was observed. By 25 days, MRI scans showed virtual resolution.

CONCLUSION

SSDHs undergo MRI signal changes that are similar to those of brain hematomas. In certain cases, even large SSDHs demonstrate swift and dramatic spontaneous resolution, despite continued anticoagulation treatment. This report suggests that there is a role for conservative management for selected cases of SSDHs.

Cerebral cavernous malformations: natural history and prognosis after clinical deterioration with or without hemorrhage

Despite recent studies of the natural history of cavernous malformations, there remains significant uncertainty concerning hemorrhage rates and the importance of lesion location. Controversy arises over varying definitions of "hemorrhage." What is ultimately important to the patient is the occurrence of a neurological event, which may or may not be associated with radiologically documented hemorrhage, as well as the chance of recovery after such an event. The purpose of this study was to determine the rates of occurrence and sequelae of neurological events in 173 patients referred to our vascular malformation clinic with cavernous malformations. All patient data were entered into a database. The mean age at presentation for the 173 patients was 37.5 years. The lesion location was deep (brainstem, cerebellar nuclei, thalamus, or basal ganglia) in 64 patients (37%) and superficial in 109 (63%). Thirty-one patients (18%) had multiple lesions. Disease presentation was due to seizures in 62 patients (36%), hemorrhage in 44 (25%), focal neurological deficit without documented hemorrhage in 35 (20%), headache alone in 11 (6%), and incidental findings in 21 patients (12%). The results obtained in the 110 patients eligible for follow-up review were used to derive information on the rates of hemorrhage and neurological events. An interval event (neurological deterioration) required both symptoms and signs. The total mean follow-up period was 46 months, the majority (65%) of which was prospective. There were 18 interval events in 427 patient-years of follow-up review, for an overall annual event rate of 4.2%. Location was the most important factor for predicting interval event occurrence, with significantly higher rates for deeply located (10.6%/year) compared with superficially located lesions (0%/year) (p = 0.0001). Of patients suffering a neurological event, only 37% had complete resolution of their deficits. This largely prospective study indicates that deep cavernous malformations carry a worse prognosis than superficial lesions with respect to annual rates of neurological deterioration. The alarming rate of adverse clinical events occurring in patients with deep lesions is punctuated by the fact that less than one-half of them recover fully during long-term follow-up review.

Endovascular management of vertebral arteriovenous fistulas: the Toronto experience

OBJECTIVE

This study was designed to evaluate the effectiveness of the endovascular management under angiographic control of vertebral arteriovenous fistulas (AVF).

DESIGN

The study included a retrospective chart review.

METHOD

Of the eight patients with AVF (2 traumatic, 6 spontaneous) referred to the interventional neuroradiology group at the Toronto Hospital between May 1986 and August 1994, endovascular embolization was attempted in six cases.

RESULTS

All cases were successful, with no residual fistula flow, mortality, or morbidity.

CONCLUSIONS

Vertebral AVFs are rare; therefore, most centres have had limited experience with their management. Endovascular management has proven to be less difficult and to have less morbidity than surgical management in these cases.

Listeria spinal cord abscess--clinical and MRI findings

BACKGROUND

Intramedullary spinal cord abscess due to Listeria Monocytogenes is an uncommon condition usually affecting immunocompromised patients.

METHOD

Case study.

RESULTS

A 69-year-old man presented with 3 weeks history of subacute paralysis of both lower limbs and the left upper limb. Myelogram and CT scan showed a widened upper cervical cord. CSF revealed lymphocytosis, moderately elevated protein and depressed glucose. A gadolinium-enhanced MRI showed diffuse cervical cord edema with two ring-enhancing lesions at C2-C3. Blood and CSF cultures grew Listeria Monocytogenes. He received IV ampicillin and gentamycin; the latter was discontinued after 1 month due to nephrotoxicity. Serial MRI over the next 3 months showed significant reduction in the size of these abscesses. The patient made a modest improvement in the power of his lower limbs, however he remained bed-ridden. Aside from being a mild, diet-controlled diabetic, there was no evidence of immunosuppression.

CONCLUSION

Listeria spinal cord abscess is a treatable disorder and should be considered in the differential diagnosis in patients with a subacute onset of spinal cord dysfunction.

Spontaneous meningocele, a rare middle ear mass

This report describes the CT and MR findings in one patient with a spontaneous middle ear meningocele and a second patient with a middle ear meningoencephalocele possibly related to a large intracranial mass. High-resolution CT defined anatomic relation and bone destruction, and MR aided in tissue characterization.

Posttreatment MR findings in spinal dural arteriovenous malformations

PURPOSE

To review the MR findings in 17 patients with spinal dural arteriovenous malformations and compare posttreatment MR with clinical outcome in 10 patients.

METHODS

Extramedullary flow voids, cord swelling, and intramedullary signal changes were recorded in 17 patients. Enhancement and vessel cospicuity were assessed in 10 patients given gadopentetate dimeglumine. In 10 patients, follow-up MR was correlated with clinical outcome.

RESULTS

Of the 17 patients, 14 (82%) had abnormal subarachnoid vessels, 11 (65%) had cord enlargement, and 16 (94%) had hyperintensity on T2-weighted images. In 3 patients, the vessels were better seen with contrast, and 6 had cord enhancement. On posttreatment MR, the vessels were no longer evident in 7 of 10 patients, cord swelling resolved in 9 of 9 patients, the the T2 hyperintensity resolved or was less evident in 9 of 9 patients. Eight patients had clinical improvement, and 2 stabilized.

CONCLUSIONS

Follow-up MR showed resolution of most of the findings in spinal dural arteriovenous malformation. There was some correlation between MR and clinical outcome, but MR evaluation could not distinguish those who had improved from those who stabilized.

Embolization with temporary balloon occlusion of the internal carotid artery and in vivo proton spectroscopy improves radical removal of petrous-tentorial meningioma

A highly vascular petroclival meningioma supplied by tentorial branches of the internal carotid artery was embolized by temporary balloon occlusion of the parent vessel distal to the tumor, followed by obliteration of the tumor vascularity with polyvinyl alcohol particles. Subsequently, in vivo proton spectroscopy showed necrosis of a large portion of the tumor and helped determine the timing of surgery. Both innovative techniques considerably facilitated the subsequent radical excision of the tumor with no neurological morbidity.

Validity of test occlusion studies prior to internal carotid artery sacrifice

Twenty-nine patients with lesions of the neck, skull base, and cavernous sinus had test balloon occlusions of the internal carotid artery (ICA) to determine the feasibility of sacrifice of the artery. Only one patient (3.4%) showed evidence of cerebrovascular compromise. Sixteen patients who tolerated test occlusions went on to ICA sacrifice. Ten patients had permanent balloon occlusion (PBO) of the ICA for cavernous aneurysms or to "trap" carotid-cavernous fistulae (CCF). Complications occurred in three patients (30%) with permanent morbidity in one patient (10%). One patient with CCF had PBO of the proximal ICA only, resulting in an unstable neurologic state and ultimately in death. Two patients had resection of skull base tumors 2 and 6 days after PBO of the ICA. Both suffered strokes and one died. Three patients had surgical sacrifice of the ICA without PBO. Two of these patients suffered cerebral ischemia without permanent sequelae. We conclude that test occlusion of the ICA with clinical monitoring will miss a significant number of patients with inadequate cerebrovascular reserve. Sensitivity is improved by controlled reduction of systemic blood pressure during the test occlusion. Resection of a skull base tumor soon after PBO of the ICA should be done in a delayed fashion or preceded by extracranial-intracranial arterial bypass. Patients who have had the artery sacrificed should be monitored in an intensive care setting for 48 hours to avoid hypotension, which could cause cerebrovascular ischemia.

Delayed angiography in the investigation of intracerebral hematomas caused by small arteriovenous malformations

We reviewed the clinical and radiological features of ten patients with small arteriovenous malformations that caused intracerebral hematomas. In six patients, angiography showed a small nidus (less than 1 cm in diameter) with a shunt at the site of the hematoma, and in four only an early-filling vein was evident. Six patients had only delayed angiography (4 weeks or more after the ictus). In three, angiography within 2 days of the ictus failed to reveal the cause of the bleed, but repeat angiography showed an early-filling vein in two, and a nidus with shunting in one. In only one patient did early angiography reveal the malformation. MRI was obtained in eight patients, and in two prominent vessels were evident in the wall of the hematoma cavity. In investigation of an unexplained intracerebral hematoma, MRI may be useful to exclude a neoplasm or cavernoma, although the latter may be not be evident in the presence of a recent hematoma. We suggest early MRI and angiography for investigation of an unexplained, nonhypertensive intracerebral bleed, with follow-up MRI and delayed angiography if the initial studies fail to reveal the cause.

Tinnitus: imaging algorithms

The causes of tinnitus can be grouped according to whether the noise is continuous or pulsatile, whether it is subjective or objective and whether there is a retrotympanic mass. Imaging algorithms can be based on these symptoms and signs. For patients with nonpulsatile tinnitus and a normal drum, magnetic resonance imaging is preferred if a retrocochlear lesion is suspected, whereas high-resolution computed tomography (HRCT) is recommended if a cochlear abnormality is likely. If a chronic inflammation in the middle ear is suspected, HRCT is the study of choice to differentiate cholesteatoma from chronic otitis media. If the bruit is objective and the tympanic membrane normal, selective cerebral angiography should be the initial investigation, because most such patients have an acquired vascular abnormality, usually a dural arteriovenous fistula. If there is pulsatile tinnitus and a retrotympanic mass, HRCT should be the first examination because this technique allows differentiation of a vascular variation, such as an aberrant carotid artery or jugular dehiscence, from a paraganglioma.

Aberrant carotid artery: recognition on high resolution computed tomography

In the investigation of a pulsatile retrotympanic mass it is important to recognize the high resolution computed tomography findings of an aberrant internal carotid artery. These include an absent exocranial opening of the carotid canal and a tubular density coursing along the medial wall of the middle ear in continuity with the horizontal carotid canal through a dehiscence of the lateral carotid plate. Our report highlights an unusual variation where two anomalous arteries, an aberrant internal carotid and an inferior tympanic to petrous carotid anastomoses, course through the middle ear.

Posttraumatic Ligamentous Disruption of the Cervical Spine, an Easily Overlooked Diagnosis: Presentation of Three Cases

Three patients with hyperflexion sprain of the cervical spine secondary to motor vehicle accidents are discussed. One patient exhibited tetraplegia and the other two only had paresthesia of the upper and/or lower extremities at the scene of the accident. All patients were young with no evidence of degenerative disc disease or osteoarthritis. Diagnosis of hyperflexion sprain is suggested by transient or persistent neurological deficits, local tenderness, or plain film findings, which include interspinous fanning, localized kyphotic angulation, subluxation, or disc space narrowing. Review of our patients' records revealed that some of these findings were evident at their initial presentation. In patients who have no neurological deficits, controlled flexion and extension views after routine plain films may be diagnostic of an unstable cervical spine. If there is a persistent neurological deficit, a magnetic resonance imaging scan is the examination of choice. If there is no compression of the thecal sac or spinal cord, supervised flexion and extension views of cervical spine should be done. Definitive management of the unstable spine is operative fixation.

Posttraumatic ligamentous disruption of the cervical spine, an easily overlooked diagnosis: presentation of three cases

Three patients with hyperflexion sprain of the cervical spine secondary to motor vehicle accidents are discussed. One patient exhibited tetraplegia and the other two only had paresthesia of the upper and/or lower extremities at the scene of the accident. All patients were young with no evidence of degenerative disc disease or osteoarthritis. Diagnosis of hyperflexion sprain is suggested by transient or persistent neurological deficits, local tenderness, or plain film findings, which include interspinous fanning, localized kyphotic angulation, subluxation, or disc space narrowing. Review of our patients' records revealed that some of these findings were evident at their initial presentation. In patients who have no neurological deficits, controlled flexion and extension views after routine plain films may be diagnostic of an unstable cervical spine. If there is a persistent neurological deficit, a magnetic resonance imaging scan is the examination of choice. If there is no compression of the thecal sac or spinal cord, supervised flexion and extension views of cervical spine should be done. Definitive management of the unstable spine is operative fixation.

Multiple cerebral arteriovenous malformations (AVMs). Review of our experience from 203 patients with cerebral vascular lesions

From our series of 203 patients with cerebral vascular lesions, 18 (9%) could be included in the multiple arteriovenous malformation category. There were five patients with Rendu-Osler-Weber, one with Wyburn-Mason syndromes and two with concurrent arteriovenous malformations. The remaining ten patients (4%) had multiple brain arteriovenous malformations. Careful angiography with magnification is necessary to try to diagnose multiple brain AVMs, since these sometimes become apparent only after embolization of a larger dominant AVM. The incidence of multiple brain arteriovenous malformations is likely to have been underestimated due to the failure to recognize micro-arteriovenous malformations associated with larger arteriovenous malformations.

Psychological, topographic EEG, and CT scan correlates of frontal lobe function in schizophrenia

This study examined frontal lobe function in a group of 20 patients with schizophrenia, on and off medication, compared to 20 normals matched for age, sex, handedness, intelligence, and educational level. Schizophrenic patients generally did not perform as well as normals on the Wisconsin Card Sorting Test (WCST). Patients off medication performed less well on this test than those on medication. Those on medication did not perform as well as those off medication on the design and word fluency tests, which suggested that medications may affect various aspects of frontal lobe function differently. During the WCST, normal subjects demonstrated an increase in beta mean frequency of the electroencephalogram in frontal and centrotemporal regions which was not statistically significant in either schizophrenic group. This shift in beta mean frequency was found to correlate positively with performance on the WCST in normals, but not in patients. Patients with more negative symptoms tended to show a smaller increase in beta mean frequency during the WCST. Performance on the WCST was correlated negatively with ventricle-brain ratio in all subjects, suggesting that frontal lobe function might be related to computed tomographic measures in the normal population as well as in schizophrenic patients. There was no correlation with performance on the WCST and length of illness.

Reversal of cluster headache side following treatment of arteriovenous malformation

We describe the case of a forty-four year old man who had typical right sided cluster headaches and an arteriovenous malformation supplied mainly by the right anterior cerebral artery. Following endovascular embolisation of this artery the AVM was supplied mainly by the left anterior cerebral artery. Subsequent headaches have always been on the left. Transcranial Doppler studies now suggested an increase of middle cerebral artery flow velocity. We suggest that the change in haemodynamics was responsible for the change in headache side.

Computed tomography of lingual thyroid

The CT findings of a lingual thyroid are presented. A round, well-defined, homogeneously enhancing mass at the base of the tongue suggested the diagnosis leading to the confirmatory isotope scan.

Epidermoid tumor: an unusual cause of ossification within the spinal canal

Epidermoid tumors of the spinal canal are rare. We report two patients with intraspinal lesions and radiographically evident calcification. One proved to have an epidermoid tumor. Although the tissue diagnosis in the second was not definitive, it suggested an epidermoid tumor as well. Radiographically visible ossification or calcification has not been reported before in intraspinal epidermoids.

CT of myeloma involving the skull base

We report three patients with myeloma involving the skull base. A large extracranial soft-tissue mass, intracranial extension, homogeneous enhancement, smooth margins, and bone remodelling were features common to the three lesions. In two patients the lesions extended into the orbit with one patient presenting with proptosis.