Category: Vascular

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Awake mapping for resection of cavernous angioma and surrounding gliosis in the left dominant hemisphere

Awake mapping for resection of cavernous angioma and surrounding gliosis in the left dominant hemisphere

J Neurosurg 117:1076–1081, 2012

Maximal resection of symptomatic cavernous angioma (CA), including its surrounding gliosis if possible, has been recommended to minimize the risk of seizures or (re)bleeding. However, despite recent neurosurgical advances, such extensive CA removal is still a challenge in eloquent areas. The authors report a consecutive series of patients who underwent awake surgery for CA within the left dominant hemisphere in which intraoperative cortical– subcortical electrical stimulation was used.

Methods. Nine patients harboring a CA that was revealed by seizures in 6 cases and bleeding in 3 cases underwent resection. All CAs were located in the left dominant hemisphere: 3 temporal, 2 insular, 2 parietal, and 2 in the parietotemporal region. Awake mapping was performed in all cases by using intraoperative cortical–subcortical electrical stimulation and ultrasonography (except in 1 insular CA in which a neuronavigation system was used).

Results. Total removal of the CA was achieved in all patients, with identification and preservation of language and sensory-motor structures. In addition, the pericavernomatous gliosis was removed in 7 cases, according to the functional boundaries provided by intraoperative subcortical stimulation. In 2 cases, subcortical mapping revealed eloquent areas within the surrounding gliosis, which was voluntarily avoided. There was no postsurgical permanent deficit, no rebleeding, and no epilepsy in 7 cases (2 patients had rare seizures in the 1st year or two after surgery, and then complete arrest), with a mean follow-up of 28.5 months (range 3–64 months).

Conclusions. These results suggest that intraoperative cortical–subcortical stimulation in awake patients represents a valuable adjunct to image-guided surgery with the aim of selecting the safer surgical approach for CAs involving eloquent areas. Moreover, such online mapping can be helpful when removing the pericavernomatous gliosis while preserving functional structures, which can persist within the hemosiderin rim. Thus, the authors propose that awake surgery be routinely considered, both to optimize the resection and to improve the quality of life through seizure control and avoidance of (re)bleeding for CAs located in the left dominant hemisphere.

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Safety and Efficacy of Intraoperative Angiography in Craniotomies for Cerebral Aneurysms and Arteriovenous Malformations

Intraoperative angiography in aneurysms surgery

Neurosurgery 71:1162–1169, 2012

In an era of indocyanine angiography, the routine use of intraoperative angiography (IOA) in the surgical treatment of aneurysms and vascular malformations is controversial.

OBJECTIVE: To retrospectively assess the safety and efficacy of IOA and to determine predictors of surgical revision.

METHODS: Between 2003 and 2011, IOA was performed during surgical treatment of 976 aneurysms, 101 arteriovenous malformations (AVMs), and 16 arteriovenous fistulas.

RESULTS: In 80 of 976 aneurysms (8.2%), IOA prompted clip repositioning. The reason for readjustment was residual aneurysm in 54.7%, parent vessel occlusion in 42.9%, and both in 2.4% of cases. In multivariate analysis, increasing aneurysm size (P,.001), ruptured aneurysm (P,.001), and increasing number of vessels injected (P,.001) were strong predictors of clip readjustment. There was a strong trend for posterior circulation aneurysm location to predict clip repositioning (P = .06). IOA revealed residual nidus/ fistula requiring further intervention in 9 of 101 AVMs (8.9%) and 3 of 16 arteriovenous fistulas (18.8%). Of 9 AVMs requiring a surgical revision, 2 (22.2%) were Spetzler-Martin grade II, 5 (55.6%) were grade III, and 2 (22.2%) were grade IV. Mean Spetzler-Martin grade was 3.0 in AVMs requiring surgical revision compared with 2.3 in those not requiring revision (P = .05). IOA-related complications were all transient or minor and occurred in 0.99% of patients; none resulted in permanent morbidity.

CONCLUSION: IOA remains a valuable tool in the surgical treatment of brain vascular abnormalities, guiding surgical re-exploration in >8% of cases. Easy access to an angiographer and routine use of IOA are important factors contributing to procedural safety and efficacy.

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Selective-Targeted Extra-Intracranial Bypass Surgery in Complex Middle Cerebral Artery Aneurysms: Correctly Identifying the Recipient Artery Using Indocyanine Green Videoangiography

Neurosurgery 71[ONS Suppl 2]:ons274–ons285, 2012

Treatment of complex middle cerebral artery (MCA) aneurysms often requires vessel sacrifice or prolonged temporary occlusion with extra- to intracranial (EC-IC) bypass to preserve perfusion. A crucial surgical step is the identification of the bypass recipient artery matching the distal territory of the involved vessel.

OBJECTIVE: To report about the feasibility and efficiency of an indocyanine green videoangiography (ICG-VA) assisted technique for identification of cortical recipient vessels to perform selective-targeted EC-IC bypass.

METHODS: The proposed technique is based on the analysis of differences in the timing of filling of M4 vessels seen on serial ICG-VAs. A delayed fluorescence can be visualized either primarily on a baseline ICG-VA or secondarily on an ICG-VA performed during temporary occlusion of the involved MCA branch. M4 branches presenting delayed fluorescence represent suitable bypass recipient arteries. We report 7 consecutive patients treated for complex MCA aneurysms with selective-targeted EC-IC bypass.

RESULTS: Application of the proposed technique permitted the correct identification of recipient arteries (cortical branches of the involved MCA segment) in all patients. The cortex distal to the occlusion filled concomitantly on ICG-VA at the end of surgery. All patients underwent successful treatment of the aneurysm, including a cortical bypass. There were no ischemic complications, and a favorable clinical outcome was achieved in all patients (modified Rankin Scale at follow-up # modified Rankin Scale preoperative).

CONCLUSION: The proposed ICG-VA-based technique enables reliable and accurate identification of the cortical recipient artery and eliminates the risk of erroneous revascularization of noninvolved territories.

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Cerebellar Arteriovenous Malformations: Anatomic Subtypes, Surgical Results, and Increased Predictive Accuracy of the Supplementary Grading System

Neurosurgery 71:1111–1124, 2012

Anatomic diversity among cerebellar arteriovenous malformations (AVMs) calls for a classification that is intuitive and surgically informative. Selection tools like the Spetzler-Martin grading system are designed to work best with cerebral AVMs but have shortcomings with cerebellar AVMs.

OBJECTIVE: To define subtypes of cerebellar AVMs that clarify anatomy and surgical management, to determine results according to subtypes, and to compare predictive accuracies of the Spetzler-Martin and supplementary systems.

METHODS: From a consecutive surgical series of 500 patients, 60 had cerebellar AVMs, 39 had brainstem AVMs and were excluded, and 401 had cerebral AVMs.

RESULTS: Cerebellar AVM subtypes were as follows: 18 vermian, 13 suboccipital, 12 tentorial, 12 petrosal, and 5 tonsillar. Patients with tonsillar and tentorial AVMs fared best. Cerebellar AVMs presented with hemorrhage more than cerebral AVMs (P,.001). Cerebellar AVMs were more likely to drain deep (P = .04) and less likely to be eloquent (P,.001). The predictive accuracy of the supplementary grade was better than that of the Spetzler-Martin grade with cerebellar AVMs (areas under the receiver-operating characteristic curve, 0.74 and 0.59, respectively). The predictive accuracy of the supplementary system was consistent for cerebral and cerebellar AVMs, whereas that of the Spetzler-Martin system was greater with cerebral AVMs.

CONCLUSION: Patients with cerebellar AVMs present with hemorrhage more often than patients with cerebral AVMs, justifying an aggressive treatment posture. The supplementary system is better than the Spetzler-Martin system at predicting outcomes after cerebellar AVM resection. Key components of the Spetzler-Martin system such as venous drainage and eloquence are distorted by cerebellar anatomy in ways that components of the supplementary system are not.

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Selective-Targeted Extra-Intracranial Bypass Surgery in Complex Middle Cerebral Artery Aneurysms: Correctly Identifying the Recipient Artery Using Indocyanine Green Videoangiography

Neurosurgery 71[ONS Suppl 2]:ons274–ons285, 2012

Treatment of complex middle cerebral artery (MCA) aneurysms often requires vessel sacrifice or prolonged temporary occlusion with extra- to intracranial (EC-IC) bypass to preserve perfusion. A crucial surgical step is the identification of the bypass recipient artery matching the distal territory of the involved vessel.

OBJECTIVE: To report about the feasibility and efficiency of an indocyanine green videoangiography (ICG-VA) assisted technique for identification of cortical recipient vessels to perform selective-targeted EC-IC bypass.

METHODS: The proposed technique is based on the analysis of differences in the timing of filling of M4 vessels seen on serial ICG-VAs. A delayed fluorescence can be visualized either primarily on a baseline ICG-VA or secondarily on an ICG-VA performed during temporary occlusion of the involved MCA branch. M4 branches presenting delayed fluorescence represent suitable bypass recipient arteries. We report 7 consecutive patients treated for complex MCA aneurysms with selective-targeted EC-IC bypass.

RESULTS: Application of the proposed technique permitted the correct identification of recipient arteries (cortical branches of the involved MCA segment) in all patients. The cortex distal to the occlusion filled concomitantly on ICG-VA at the end of surgery. All patients underwent successful treatment of the aneurysm, including a cortical bypass. There were no ischemic complications, and a favorable clinical outcome was achieved in all patients (modified Rankin Scale at follow-up # modified Rankin Scale preoperative).

CONCLUSION: The proposed ICG-VA-based technique enables reliable and accurate identification of the cortical recipient artery and eliminates the risk of erroneous revascularization of noninvolved territories.

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Comparison of Indocyanine Green Angiography and Laser Speckle Contrast Imaging for the Assessment of Vasculature Perfusion

Neurosurgery 71:1023–1031, 2012

Assessment of the vasculature is critical for overall success in cranial vascular neurological surgery procedures. Although several methods of monitoring cortical perfusion intraoperatively are available, not all are appropriate or convenient in a surgical environment. Recently, 2 optical methods of care have emerged that are able to obtain high spatial resolution images with easily implemented instrumentation: indocyanine green (ICG) angiography and laser speckle contrast imaging (LSCI).

OBJECTIVE: To evaluate the usefulness of ICG and LSCI in measuring vessel perfusion.

METHODS: An experimental setup was developed that simultaneously collects measurements of ICG fluorescence and LSCI in a rodent model. A 785-nm laser diode was used for both excitation of the ICG dye and the LSCI illumination. A photothrombotic clot model was used to occlude specific vessels within the field of view to enable comparison of the 2 methods for monitoring vessel perfusion.

RESULTS: The induced blood flow change demonstrated that ICG is an excellent method for visualizing the volume and type of vessel at a single point in time; however, it is not always an accurate representation of blood flow. In contrast, LSCI provides a continuous and accurate measurement of blood flow changes without the need of an external contrast agent.

CONCLUSION: These 2 methods should be used together to obtain a complete understanding of tissue perfusion.

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Differences in simple morphological variables in ruptured and unruptured middle cerebral artery aneurysms

J Neurosurg 117:913–919, 2012

Management of unruptured intracranial aneurysms remains controversial in neurosurgery. The contribution of morphological parameters has not been included in the treatment paradigm in a systematic manner or for any particular aneurysm location. The authors present a large sample of middle cerebral artery (MCA) aneurysms that were assessed using morphological variables to determine the parameters associated with aneurysm rupture.

Methods. Preoperative CT angiography (CTA) studies were evaluated using Slicer software to generate 3D models of the aneurysms and their surrounding vascular architecture. Morphological parameters examined in each model included 5 variables already defined in the literature (aneurysm size, aspect ratio, aneurysm angle, vessel angle, and size ratio) and 3 novel variables (flow angle, distance to the genu, and parent-daughter angle). Univariate and multivariate statistical analyses were performed to determine statistical significance.

Results. Between 2005 and 2008, 132 MCA aneurysms were treated at a single institution, and CTA studies of 79 aneurysms (40 ruptured and 39 unruptured) were analyzed. Fifty-three aneurysms were excluded because of reoperation (4), associated AVM (2), or lack of preoperative CTA studies (47). Ruptured aneurysms were associated with larger size, greater aspect ratio, larger aneurysm and flow angles, and smaller parent-daughter angle. Multivariate logistic regression revealed that aspect ratio, flow angle, and parent-daughter angle were the strongest factors associated with ruptured aneurysms.

Conclusions. Aspect ratio, flow angle, and parent-daughter angle are more strongly associated with ruptured MCA aneurysms than size. The association of parameters independent of aneurysm morphology with ruptured aneurysms suggests that these parameters may be associated with an increased risk of aneurysm rupture. These factors are readily applied in clinical practice and should be considered in addition to aneurysm size when assessing the risk of aneurysm rupture specific to the MCA location.

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Ruptured Intracranial Aneurysms With Small Basal Outpouching

Neurosurgery 71:994–1002, 2012

Recognizing an aneurysmal basal rupture using angiographic evaluation is crucial for optimal treatment.

OBJECTIVE: To evaluate the incidence of a small basal outpouching (the most common angiographic configuration suggesting a basal rupture), the incidence of a ruptured basal outpouching, and the results of surgical and endovascular treatments.

METHODS: The occurrence of small basal outpouchings was determined in the initial angiographic examinations of 471 patients with a ruptured aneurysm. Information was also obtained from patient charts, surgical and interventional reports, operative video records, and reviews of radiological investigations.

RESULTS: A small basal outpouching was identified in 41 (8.7%) of the 471 ruptured aneurysms. In the surgical series (n = 286), a basal rupture was identified in 8 (30.8%) of the 26 cases of a basal outpouching and successfully treated by aneurysm clip placement. In the endovascular series (n = 185), intraprocedural aneurysm rebleeding developed in 5 of the 15 patients (33.3%) with a basal outpouching, which was most commonly observed with anterior communicating artery aneurysms.

CONCLUSION: The current surgical series included a 9% incidence of ruptured intracranial aneurysms with a small basal outpouching, and a 31% incidence of these basal outpouchings being identified as the rupture point. The results also suggested that endovascular coiling of a basal outpouching carries a high risk of intraprocedural aneurysm rebleeding, whereas surgical clipping is safer and provides more protection against rebleeding of aneurysms with a basal rupture.

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Anterior subtemporal approach for posterolateral brainstem cavernomas

Acta Neurochir (2012) 154:2009–2016

The neuronavigation-assisted anterior subtemporal approach is proposed in this article as an alternative to surgery of posterolateral brainstem cavernomas. Brainstem cavernomas represent a neurosurgical challenge because of the high morbidity and mortality rate related to their surgical removal. Several nerve nuclei, ascending and descending fibers make this region at high risk of serious postoperative deficits.

Methods Between 1998 and 2010, 24 patients underwent surgical removal of brainstem cavernomas in our institution. Ten of these patients presented a cavernous malformation in the posterolateral region of the brainstem and underwent surgical removal by means of a neuronavigation-assisted anterior subtemporal approach.

Results Lesion removal was complete for all patients. There were no cases of surgery-related death. Neurological status improved or remained unchanged after surgery in all cases. All patients presented good outcomes at 12 to 154 months’ follow-up (mean 70 months; GOS05 in 8/10 patients, 4 in 2/10 patients; mRS00–1 in all patients). Only one patient presented transient confusion, aphasia and seizures related to temporal lobe swelling, which resolved completely within a few days. One patient developed cranial nerve III palsy and left hemiparesis with gradual recovery.

Conclusions This approach represents a valid alternative to the “more classical” approaches for the surgery of posterolateral cavernomas of the pontomesenchephalic junction reaching the tentorial incisura, reducing the risk of damaging the vein of Labbé, temporal lobe swelling, cerebellar swelling, ophtalmoparesis, fourth ventricle cranial nerve nuclei lesions. Skeletonization of sigmoidal sinus provides with good outcomes, low morbidity and mortality.

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Management of non-traumatic intraventricular hemorrhage

Neurosurg Rev (2012) 35:485–495

Intraventricular hemorrhage (IVH) is defined as the eruption of blood in the cerebral ventricular system and is mostly secondary to spontaneous intracerebral hemorrhage and aneurysmal and arteriovenous malformation rupture. IVH is a proven risk factor of increased mortality and poor functional outcome. Its seriousness is correlated not only with the amount of blood but also with the involvement of the third and fourth ventricles.

There are four mechanisms that explain the pathophysiology of this event: acute obstructive hydrocephalus, the mass effect exerted by the blood clot, the toxicity of bloodbreaking products on the adjacent brain parenchyma, and, lastly, the development of a chronic hydrocephalus. It is thus obvious that the clearance of blood from the ventricles should be a therapeutic goal.

In cases of acute hydrocephalus, external ventricular drainage is a mandatory step, but proven often insufficient. The concomitant use of intraventricular fibrinolytics such as recombinant tissue plasminogen activator or urokinase seems to be beneficial at least in the context of spontaneous intracerebral hemorrhage, in which their use is now accepted but not yet validated by a randomized trial. Given the potential neurotoxicity of these agents, further research is needed in order to identify the best treatment for intraventricular fibrinolysis (IVF).

The endoscopic retrieval of intraventricular blood was also described recently and seems to be as efficient as IVF, but its use is limited to specialized centers.

IVH represents a therapeutic challenge for neurosurgeons, neurologists, and intensivists. Thus, a better understanding of this dramatic event will help in better tailoring the treatment strategies.

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Clinical presentation and treatment of distal anterior inferior cerebellar artery aneurysms

Neurosurg Rev (2012) 35:497–504

Aneurysms located at the distal portion of the anterior inferior cerebellar artery (AICA) are rare, and their clinical features are not fully understood. We report the clinical features and management of nine distal AICA aneurysms in nine patients treated during the past decade at Kagoshima University Hospital and affiliated hospitals.

Our series includes seven women and two men. Of their nine aneurysms, eight were ruptured and one was unruptured; six were saccular and three were dissecting aneurysms. The most prevalent location was the meatal loop (n=5) followed by the postmeatal (n=3) and premeatal segment (n=1) of the AICA, suggesting hemodynamic stress as an etiology of these distal AICA aneurysms. Of the nine patients, five presented with angiographic features suggestive of increased hemodynamic stress to the AICA and the common trunk of the posterior inferior cerebellar artery, with vertebral artery stenosis, marked laterality, and a primitive hypoglossal artery.

We addressed eight aneurysms (eight patients) surgically; one aneurysm in one patient disappeared in the course of 3 months without surgical treatment. Of the eight surgically treated aneurysms, seven were ruptured and one was unruptured, five were clipped via lateral suboccipital craniotomy, two were trapped via lateral suboccipital craniotomy, and one was embolized. Good outcomes were obtained in six of the eight patients who underwent operation (75 %).

We consider increased hemodynamic stress attributable to anatomic variations in the AICA and related posterior circulation to be the predominant contributor to the development of distal AICA aneurysms. Direct clipping and trapping yielded favorable outcomes in our series.

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Safety and Efficacy of Endovascular Treatment of Basilar Tip Aneurysms by Coiling With and Without Stent Assistance: A Review of 235 Cases

Neurosurgery 71:785–794, 2012

Endovascular therapy is now the preferred treatment option for basilar tip aneurysms (BTAs).

OBJECTIVE: To compare the safety and efficacy of common endovascular techniques in the treatment of BTAs.

METHODS: A retrospective review was conducted of 235 patients with BTAs treated with endovascular means in our institution between 2004 and 2011. Categorization was based on the presence and type of stent assistance (none, single, and Y stenting). The rates of perioperative complications, recanalization, rehemorrhage, and retreatment were analyzed.

RESULTS: A total of 147 patients were treated with coil embolization and 88 patients with stent-assisted coiling (72 single stents, 16 Y stents). Thromboembolic complications occurred in 6.8% of patients in both groups. There was no associated mortality. Angiographic follow-up (mean, 23.5 months) was available in 172 patients (77.1%). Stented patients had significantly lower recanalization (17.2% vs 38.9%; P = .003) and retreatment (7.8% vs 27.8%; P = .002) rates compared with nonstented patients. Four rehemorrhages (2.7%) occurred in the coiled group, whereas none were noted in the stented group (P = .3). In paired comparisons, lower recanalization (8.3% vs 19.2%; P = .21) and retreatment (0% vs 9.6%; P = .19) rates were seen in the Y-stent group compared with the single-stent group. Thromboembolic complications occurred in 6.9% and 6.2% of patients in the single-stent and Y-stent groups, respectively (P = .91). In multivariate analysis, larger aneurysms, nonstented aneurysms, incomplete initial occlusion, and subarachnoid hemorrhage were predictors of aneurysm recanalization.

CONCLUSION: Stent-assisted coiling has significantly lower recurrence, retreatment, and rehemorrhage rates than coiling alone for the treatment of BTAs. Y stenting has the highest efficacy with low complication rates.

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Removal of an ICH through an eyebrow incision

J Neurosurg 117:767–773, 2012

Surgical evacuation of spontaneous intracerebral hemorrhage (sICH) remains a subject of controversy. Minimally invasive techniques for hematoma evacuation have shown a trend toward improved outcomes. The aim of the present study is to describe a minimally invasive alternative for the evacuation of sICH and evaluate its feasibility.
Methods
The authors reviewed records of all patients who underwent endoscopic evacuation of an sICH at the UCLA Medical Center between March 2002 and March 2011. All patients in whom the described technique was used for evacuation of an sICH were included in this series. In this approach an incision is made at the superior margin of the eyebrow, and a bur hole is made in the supraorbital bone lateral to the frontal sinus. Using stereotactic guidance, the surgeon advanced the endoscopic sheath along the long axis of the hematoma and fixed it in place at two specific depths where suction was then applied until 75%–85% of the preoperatively determined hematoma volume was removed. An endoscope’s camera, then introduced through the sheath, was used to assist in hemostasis. Preoperative and postoperative hematoma volumes and reduction in midline shift were calculated and recorded. Admission Glasgow Coma Scale and modified Rankin Scale (mRS) scores were compared with postoperative scores.
Results
Six patients underwent evacuation of an sICH using the eyebrow/bur hole technique. The mean preoperative hematoma volume was 68.9 ml (range 30.2–153.9 ml), whereas the mean postoperative residual hematoma volume was 11.9 ml (range 5.1–24.1 ml) (p = 0.02). The mean percentage of hematoma evacuated was 79.2% (range 49%–92.7%). The mean reduction in midline shift was 57.8% (p < 0.01). The Glasgow Coma Scale score improved in each patient between admission and discharge examination. In 5 of the 6 patients the mRS score improved from admission exam to last follow-up. None of the patients experienced rebleeding.
Conclusions
This minimally invasive technique is a feasible alternative to other means of evacuating sICHs. It is intended for anterior basal ganglia hematomas, which usually have an elongated, ovoid shape. The approach allows for an optimal trajectory to the long axis of the hematoma, making it possible to evacuate the vast majority of the clot with only one pass of the endoscopic sheath, theoretically minimizing the amount of damage to normal brain.

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Near-infrared indocyanine green videoangiography (ICGVA) and intraoperative computed tomography (iCT): are they complementary or competitive imaging techniques in aneurysm surgery?

Acta Neurochir (2012) 154:1861–1868

In this pilot study we compared advantages and drawbacks of near-infrared indocyanine green videoangiography (ICGVA) and intraoperative computed tomography (iCT) to investigate if these are complementary or competitive methods to acquire immediate information about blood vessels and potential critical impairment of brain perfusion during vascular neurosurgery.
Methods
A small subset of patients (n = 10) were prospectively enrolled in this feasibility study and received ICGVA immediately after placement of the aneurysm clips. An intraoperative cranial CT angiography (iCTA) was followed by dynamic perfusion CT scan (iCTP) using a 40-slice, sliding-gantry, CT scanner. The vascular patency of major (aneurysm bearing) arteries, visualisation of arising perforating arteries and brain perfusion after clip application were analysed with both techniques.
Results
The ICGVA was able to visualise blood flow and vascular patency of all major vessels and perforating arteries within the visual field of the microscope, but failed to display vessels located within deeper areas of the surgical field. Even small coverage with brain parenchyma impaired detection of vessels. With iCTA high image quality could be obtained in 7/10 cases of clipped aneurysms. Intraoperative CTA was not sufficiently evaluable in one PICA aneurysm and one case of a previously coiled recurrent aneurysm, due to extensive coil artefacts. Small, perforating arteries could not be detected with iCTA. Intraoperative CTP allowed the assessment of global blood flow and brain perfusion in sufficient quality in 5/10 cases, and enabled adequate intraoperative decision making.
Conclusion
A combination of ICGVA and iCT is feasible, with very good diagnostic imaging quality associated with short acquisition time and little interference with the surgical workflow. Both techniques are complementary rather than competing analysing tools and help to assess information about local (ICGVA/iCTA) as well as regional (iCTA/iCTP) blood flow and cerebral perfusion immediately after clipping of intracranial aneurysms.

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A Simple and Quantitative Method to Predict Symptomatic Vasospasm After Subarachnoid Hemorrhage Based on Computed Tomography: Beyond the Fisher Scale

Neurosurgery 71:869–876, 2012

Although the Fisher scale is commonly used to grade vasospasm risk in aneurysmal subarachnoid hemorrhage (aSAH) patients, it fails to account for increasing subarachnoid hemorrhage (SAH) thickness.

OBJECTIVE: We developed a simple quantitative scale based on maximal SAH thickness and compared its reproducibility and ability to predict symptomatic vasospasm against the Fisher scale.

METHODS: The incidence of radiographic and symptomatic vasospasm among 250 aSAH patients treated at our institution was investigated. Admission head computed tomography scans were graded according to the Fisher scale and the proposed scale, which assigns a score from 1 to 5 based on a single measurement of maximum SAH thickness. We calculated vasospasm risk per grade for the Fisher scale and the proposed scale, and compared inter- and intraobserver variability for both scales.

RESULTS: Forty-five patients (20.6%) developed symptomatic vasospasm. On the proposed scale, grade 5 patients were at highest risk, with an odds ratio for symptomatic vasospasm of 11 (95% confidence interval [CI] 2.27-53.37). Odds ratios for proposed grades 4 and 3 were 4.63 (95% CI 1.10-19.59) and 3.04 (95% CI 0.85-10.90), respectively. The odds ratio for Fisher grade 3 was 3.3 (0.96-11.30). Mean inter- and intraobserver agreement was greater for the proposed scale in comparison with the Fisher scale (k0.65 and k0.81 vs k0.51 and k0.35, respectively).

CONCLUSION: The new scale accounted for increasing SAH thickness and was superior to the Fisher scale in inter- and intraobserver agreement and in predicting symptomatic vasospasm, particularly among the highest-risk patients.

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Microsurgical clipping of true posterior communicating artery aneurysms

Acta Neurochir (2012) 154:1707–1710

“True” posterior communicating artery (PCOM) aneurysms are rare variants in which the aneurysm arises solely from the PCOM rather than the junction of the internal carotid artery and the PCOM.

Methods It is critical to note that for true PCOM aneurysms, the neck arises distal to the origin of the PCOM and therefore lies in what is traditionally an intra-operative blind spot. The PCOM must be followed posteriorly to visualise the aneurysm neck for microsurgical clipping.

Conclusions A thorough pre-operative understanding of this unique anatomy is essential in minimising morbidity associated with microsurgical clipping of this aneurysm configuration.

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Independent predictors for recurrence of chronic subdural hematoma

Acta Neurochir (2012) 154:1541–1548 DOI 10.1007/s00701-012-1399-9

Chronic subdural hematoma is characterized by blood in the subdural space that evokes an inflammatory reaction. Numerous factors potentially associated with recurrence of chronic subdural hematoma have been reported, but these factors have not been sufficiently investigated. In this study, we evaluated the independent risk factors of recurrence.

Methods We analyzed data for 420 patients with chronic subdural hematoma treated by the standard surgical procedure for hematoma evacuation at our institution.

Results Ninety-two (21.9 %) patients experienced at least one recurrence of chronic subdural hematoma during the study period. We did not identify any significant differences between chronic subdural hematoma recurrence and current antiplatelet therapy. The recurrence rate was 7 % for the homogeneous type, 21 % for the laminar type, 38 % for the separated type, and 0 % for the trabecular type. The rate of recurrence was significantly lower in the homogeneous and trabecular type than in the laminar and separated type. We performed a multivariate logistic regression analysis and found that postoperative midline shifting (OR, 3.6; 95 % CI, 1.618-7.885; p00.001), diabetes mellitus (OR, 2.2; 95 % CI, 1.196-3.856; p=0.010), history of seizure (OR, 2.6; 95 % CI, 1.210-5.430; p=0.014), width of hematoma (OR, 2.1; 95 % CI, 1.287-3.538; p=0.003), and anticoagulant therapy (OR, 2.7; 95 % CI, 1.424-6.960; p=0.005) were independent risk factors for the recurrence of chronic subdural hematoma.

Conclusions We have shown that postoperative midline shifting (≥5 mm), diabetes mellitus, preoperative seizure, preoperative width of hematoma (≥20 mm), and anticoagulant therapy were independent predictors of the recurrence of chronic subdural hematoma. According to internal architecture of hematoma, the rate of recurrence was significantly lower in the homogeneous and the trabecular type than the laminar and separated type.

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Long-term Outcomes After Staged-Volume Stereotactic Radiosurgery for Large Arteriovenous Malformations

Neurosurgery 71:632–644, 2012 DOI: 10.1227/NEU.0b013e31825fd247

Stereotactic radiosurgery is an effective treatment modality for small arteriovenous malformations (AVMs) of the brain. For larger AVMs, the treatment dose is often lowered to reduce potential complications, but this decreases the likelihood of cure. One strategy is to divide large AVMs into smaller anatomic volumes and treat each volume separately.

OBJECTIVE: To prospectively assess the long-term efficacy and complications associated with staged-volume radiosurgical treatment of large, symptomatic AVMs.

METHODS: Eighteen patients with AVMs larger than 15 mL underwent prospective staged-volume radiosurgery over a 13-year period. The median AVM volume was 22.9 mL (range, 15.7-50 mL). Separate anatomic volumes were irradiated at 3- to 9-month intervals (median volume, 10.9 mL; range, 5.3-13.4 mL; median marginal dose, 15 Gy; range, 15-17 Gy). The AVM was divided into 2 volumes in 10 patients, 3 volumes in 5 patients, and 4 volumes in 3 patients. Seven patients underwent retreatment for residual disease.

RESULTS: Actuarial rates of complete angiographic occlusion were 29% and 89% at 5 and 10 years. Five patients (27.8%) had a hemorrhage after radiosurgery. Kaplan-Meier analysis of cumulative hemorrhage rates after treatment were 12%, 18%, 31%, and 31% at 2, 3, 5, and 10 years, respectively. One patient died after a hemorrhage (5.6%).

CONCLUSION: Staged-volume radiosurgery for AVMs larger than 15 mL is a viable treatment strategy. The long-term occlusion rate is high, whereas the radiation-related complication rate is low. Hemorrhage during the lag period remains the greatest source of morbidity and mortality.

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The Contralateral Transcingulate Approach

Neurosurgery 71[ONS Suppl 1]:ons4–ons14, 2012

The contralateral transcingulate approach is a variation of the contralateral transcallosal approach for lesions located in the cingulate gyrus and deep white matter of the medial frontal lobe.

OBJECTIVE: To more thoroughly describe the contralateral transcingulate approach by reporting our operative technique and results.

METHODS: This approach positions the head with the midline horizontally, lesion on the upside, allowing gravity retraction of the dependent frontal lobe. Bifrontal craniotomy and splitting of the interhemispheric fissure create a crossing trajectory from the contralateral fissure to the ipsilateral cingulate gyrus that maximizes lateral exposure.

RESULTS: Eleven patients with vascular lesions were treated with the contralateral transcingulate approach (9 patients with cavernous malformations and 2 patients with arteriovenous malformations). Eight lesions were located on the left side, 5 in the cingulate gyrus, and 6 in the deep frontal lobe. The falx was cut in 5 patients to extend the crossing trajectory. All lesions were removed completely, with neurological morbidity in 1 patient caused by venous infarction.

CONCLUSION: Although similar to the contralateral transcallosal approach, the contralateral transcingulate approach accesses lesions outside the ventricle and has a steeper crossing trajectory. This approach requires no disruption of brain tissue with lesions on the cingulate surface and only a small incision in cingulate gyrus with lesions in the deep frontal lobe. The ipsilateral pericallosal and callosomarginal arteries provide dependable landmarks for transcingulate dissection. The contralateral transcingulate approach offers an alternative medial approach to lesions near language and motor areas and avoids lateral transcortical approaches, awake speech mapping, and risk to eloquent cortex in the dominant hemisphere.

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Natural history of DAVFs without cortical venous drainage

J Neurosurg 117:539–545, 2012

The goal of this study was to determine the clinical course of Borden-Shucart Type I cranial dural arteriovenous fistulas (DAVFs) and to calculate the annual rate of conversion of these lesions to more aggressive fistulas that have cortical venous drainage (CVD).

Methods. A retrospective chart review was conducted of all patients harboring DAVFs who were seen at the authors’ institution between 1997 and 2009. Twenty-three patients with Type I DAVFs who had available clinical follow-up were identified. Angiographic and clinical data from these patients were reviewed. Neurological outcome and status of presenting symptoms were assessed during long-term follow-up.

Results. Of the 23 patients, 13 underwent endovascular treatment for intolerable tinnitus or ophthalmological symptoms, and 10 did not undergo treatment. Three untreated patients died of unrelated causes. In those who were treated, complete DAVF obliteration was achieved in 4 patients, and palliative reduction in DAVF flow was achieved in 9 patients. Of the 19 patients without radiographic cure, no patient developed intracranial hemorrhage or nonhemorrhagic neurological deficits (NHNDs), and no patient died of DAVF-related causes over a mean follow-up of 5.6 years. One patient experienced a spontaneous, asymptomatic obliteration of a partially treated DAVF in late follow-up, and 2 patients experienced a symptomatic conversion of their DAVF to a higher-grade fistula with CVD in late follow-up. The annual rate of conversion to a higher-grade DAVF based on Kaplan-Meier cumulative event-free survival analysis was 1.0%. The annual rate of intracranial hemorrhage, NHND, and DAVF-related death was 0.0%.

Conclusions. A small number of Type I DAVFs will convert to more aggressive DAVFs with CVD over time. This conversion to a higher-grade DAVF is typically heralded by a change in patient symptoms. Follow-up vascular imaging is important, particularly in the setting of recurrent or new symptoms.

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