Category: Vascular

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Contrast-Enhanced Angiographic Computed Tomography for Detection of Aneurysm Remnants After Clipping

Aneurysm

Neurosurgery 74:606–614, 2014 

For preclusion of remnants after aneurysm clipping, a reliable, noninvasive imaging technique is desirable.

OBJECTIVE: To evaluate the reliability of optimized angiographic computed tomography with intravenous contrast agent injection (ivACT) in detecting remnants after aneurysmal clipping compared with digital subtraction angiography (DSA), the gold standard.

METHODS: We included 84 patients with 112 clipped cerebral aneurysms of the anterior circulation. For treatment, 116 clips of cobalt and 57 clips of titanium alloy were used. In each patient, we performed an ivACT with dual rotational acquisition and a DSA. Data from ivACT were postprocessed with a dual-volume technique with newly implemented reconstructions modes. Aneurysm remnants were measured, classified, and correlated with DSA by 2 raters.

RESULTS: In total, 12 remnants were revealed by DSA, meaning a prevalence of 11%. IvACT demonstrated a sensitivity of 75% to 92% and a specificity of 99% in detecting remnants up to a minimal size of 0.7 · 0.3 mm. Classification of remnants by ivACT was identical to that by DSA, and assessment of size showed a significant correlation with DSA (P , .001). No significant differences between cobalt and titanium alloy were revealed concerning artifacts.

CONCLUSION: Optimized ivACT with enhanced postprocessing demonstrated high sensitivity and specificity in detecting remnants after aneurysm clipping in the anterior circulation. Classification and assessment of remnant size and detection of relevant parent artery stenosis showed high accuracy of ivACT compared with DSA. Our results indicate that ivACT might become a noninvasive alternative to DSA for postsurgical control.

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Treatment of Blister-Like Aneurysms With the Pipeline Embolization Device

Treatment of Blister-Like Aneurysms With the Pipeline Embolization Device

Neurosurgery 74:527–532, 2014

Endovascular vessel reconstruction with the pipeline embolization device (PED) has become common practice. Data on the safety and efficacy of the PED in blister-like aneurysms (BLAs) are limited.

OBJECTIVE: To retrospectively present our experience with use of the PED in BLAs.

METHODS: A total of 8 patients harboring 8 BLAs were treated with the PED at our institution between November 2011 and April 2013.

RESULTS: Aneurysm size was 2.5 mm on average. Five patients had sustained a subarachnoid hemorrhage (SAH), 1 patient presented with sentinel headaches, and in 2 patients the aneurysm was incidentally discovered. Seven aneurysms arose from the ICA and 1 from the basilar artery. Placement of the PED was successful in all 8 patients. There were no procedural or perioperative complications in any of the patients. At the latest follow-up, all 8 patients achieved a favorable outcome (mRS 0-2). Angiographic follow-up was available for 6 patients at a mean time point of 3.9 months. Follow-up angiography showed 100% aneurysm occlusion in 5 patients and marked decrease in aneurysm size in 1 patient.

CONCLUSION: The findings of this study suggest that the PED may be a safe and effective treatment for BLAs. Given the limitations of other treatment modalities and the challenging nature of BLAs, flow diversion may be a valuable option for these lesions.

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Occipital artery to posterior inferior cerebellar artery bypass

How I do it- occipital artery to posterior inferior cerebellar artery bypass

Acta Neurochir (2014) 156:971–975

Aneurysms located at the proximal posterior inferior cerebellar artery (PICA) may need to be addressed by trapping and concomitant bypass. An anastomosis of the Occipital Artery (OA) to PICA is one bypass option in these cases. This bypass is highly challenging and its technical description is seldom cited in the literature.

Methods We describe the technical nuances of an OA-PICA end-to-side bypass in a 63-year-old man with a dissecting ruptured aneurysm of the third segment (tonsilomedullary) of the PICA.

Conclusion OA-PICA bypass option should remain as a treatment modality in the armamentarium of neurovascular surgeons.

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Risks and benefits of CT angiography in spontaneous intracerebral hemorrhage

ct_spot_sign

Acta Neurochir (2014) 156:911–917

Few studies have examined the risk of computed tomography angiography (CTA) during the acute phase of spontaneous intracerebral hemorrhage (ICH), while the benefits of CTA in ICH have been well-documented. The present study investigated both the benefits of identifying spot signs, which are supposed to indicate hematoma enlargement after admission, and risks of CTA performed during the acute phase of ICH.

Methods We retrospectively assessed 323 consecutive patients with spontaneous ICHs admitted to our hospital between April 2009 and March 2012 and who underwent CTA on admission.

Results In 80 patients (24.7 %), spot signs were demonstrated on CTA source images. Multivariate analysis revealed two independent factors correlated with presence of the spot sign: age and hematoma volume (p<0.05 each). The presence of spot sign was associated with unfavorable outcomes at discharge and hematoma growth after admission (p<0.05 each). Adverse events related to CTA occurred in 17 patients (5.2 %), including transient renal dysfunction in 16 patients and allergy to contrast medium in one patient. All adverse events completely resolved within 1 week.

Conclusions Presence of the spot sign indicated the possibility of hematoma growth and unfavorable outcomes. A small number of adverse events occurred in association with CTA, but without any permanent deficits. Given the potential benefits and risks, we believe that CTA performed at admission in all patients with ICH is beneficial to improve the outcomes.

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Recovery from oculomotor nerve palsy due to posterior communicating artery aneurysms: results after clipping versus coiling in a single-center series

Recovery from oculomotor nerve palsy due to posterior communicating artery aneurysms- results after clipping versus coiling in a single-center series

Acta Neurochir (2014) 156:879–884

Oculomotor nerve palsy (ONP) is a common clinical manifestation of ruptured or unruptured posterior communicating artery (PcomA) aneurysms. Although microsurgical clip ligation has been proven a safe and durable treatment, endovascular management is emerging as an increasingly popular alternative. The aim of our study is to compare the recovery rate from ONP and assess the safety and long-term durability of both techniques.

Methods We have reviewed the retrospective data concerning twenty-two patients treated at our institution between 2004 and 2012 for PcomA aneurysms with ONP. Seven patients were operated on via a standard pterional approach, and fourteen were treated by endovascular occlusion with coils. One patient was managed conservatively. Pre-treatment and post-treatment severity of ONP was recorded, as well as the duration of symptoms before admission and treatment-related complications.

Results All seven patients who underwent surgery improved, with six total recoveries and one partial recovery. Among the fourteen patients treated by embolization, thirteen initially recovered, but long-term follow-up revealed three cases of exacerbation of ONP after refilling of the aneurysms. Two of them were clipped, and one embolized. Also, one partially resolved patient underwent a second embolization. No severe complications occurred in either group.

Conclusions Despite the small number of patients, our study suggests that both surgical clipping and embolization are safe and effective methods in regards to functional recovery (complete ONP recovery in about 85 % of the cases). However, coiling may lead to delayed recurrence of third cranial nerve (CN) palsy at long-term follow-up, requiring additional treatment. Keywords

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Long-term natural history of incidentally discovered cavernous malformations in a single-center cohort

cavmal2_600

J Neurosurg 120:1188–1192, 2014

The aim of this study was to determine the prospective hemorrhage rate in a group of retrospectively identified patients in whom symptoms had an unclear relationship to an intracerebral cavernous malformation (ICM) or the malformation itself was an incidental finding.

Methods. Patients with incidentally discovered ICMs diagnosed between 1989 and 1999 were identified from a previously published cohort. Those with ICMs having an unclear relationship with existing symptoms were also eligible for analysis. Updated clinical and radiographic data pertaining to symptomatic intracerebral hemorrhage related to the ICM or new seizures were obtained through medical chart review and mail survey. In select patients, phone calls were made and death certificates were obtained when possible. The prospective hemorrhage rate was calculated as the number of prospective hemorrhages divided by the number of patient-years of follow-up.

Results. There were 1311 patient-years of follow-up among the 107 patients (49.5% male; mean age at diagnosis 52 years) eligible for this study. Forty-four patients died in the follow-up period, and the cause of death could be determined in 34 (77%). Two patients had a prospective hemorrhage, which was definitively related to the ICM in only one. Thus, the definitive prospective bleed rate was 0.08% per patient-year. No new seizures developed in any of the patients during the follow-up period.

Conclusions. The risk of prospective hemorrhage in patients presenting asymptomatically with ICM is very low. This information can be useful in managing such patients and may be most applicable to those with a single ICM.

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Revascularization and Aneurysm Surgery: Techniques, Indications, and Outcomes in the Endovascular Era

Revascularization and Aneurysm Surgery

Neurosurgery 74:482–498, 2014

Given advances in endovascular technique, the indications for revascularization in aneurysm surgery have declined.

OBJECTIVE: We sought to define indications, outline technical strategies, and evaluate the outcomes of patients treated with bypass in the endovascular era.

METHODS: We retrospectively reviewed all aneurysms treated between September 2006 and February 2013.

RESULTS: We identified 54 consecutive patients (16 males and 39 females) with 56 aneurysms. Aneurysms were located along the cervical internal carotid artery (ICA) (n = 1), petrous/cavernous ICA (n = 1), cavernous ICA (n = 16), supraclinoid ICA (n = 7), posterior communicating artery (n = 2), anterior cerebral artery (n = 4), middle cerebral artery (MCA) (n = 13), posterior cerebral artery (PCA) (n = 3), posterior inferior cerebellar artery (n = 4), and vertebrobasilar arteries (n = 5). Revascularization was performed with superficial temporal artery (STA) to MCA bypass (n = 25), STA to superior cerebellar artery (SCA) (n = 3), STA to PCA (n = 1), STA-SCA/STA-PCA (n = 1), occipital artery (OA) to PCA (n = 2), external carotid artery/ICA to MCA (n = 15), OA to MCA (n = 1), OA to posterior inferior cerebellar artery (n = 1), and in situ bypasses (n = 8). At a mean clinical follow-up of 18.5 months, 45 patients (81.8%) had a good outcome (Glasgow Outcome Scale 4 or 5). There were 7 cases of mortality (12.7%) and an additional 9 cases of morbidity (15.8%). At a mean angiographic follow-up of 17.8 months, 14 bypasses were occluded. Excluding the 7 cases of mortality, the majority of aneurysms (n = 42) were obliterated. We identified 7 cases of residual aneurysm and recurrence in 6 patients at follow-up.

CONCLUSION: Given current limitations with existing treatments, cerebral revascularization remains an essential technique for aneurysm surgery.

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Re-exploration of the craniotomy after surgical treatment of unruptured intracranial aneurysms

Cranio re-exploration for aneu

Acta Neurochir (2014) 156:869–877

Unplanned re-exploration of the craniotomy after surgical treatment of unruptured intracranial aneurysms (UIAs) is sometimes required, but the underlying causes and rates of these procedures are seldom reported. This study retrospectively analyzed the causes of such re-explorations to identify methods for decreasing their necessity.

Method From January 2000 to December 2011, 1,720 patients with a total of 1,938 UIAs underwent surgical treatment at our institution. Fromthis cohort, 26 patients (1.5 %) with 38 UIAs required re-exploration. Clinical data, aneurysm characteristics, treatment methods, and the incidence and causes of re-exploration of the craniotomy were analyzed for these 26 patients.

Results: Several causes of re-exploration were identified: compromised distal blood flow (eight patients, 0.47 %), hemorrhagic venous infarction (four patients, 0.23 %), brain retraction injury (three patients, 0.17 %), newly identified aneurysms (three patients, 0.17 %), bleeding from an incompletely clipped aneurysm (two patients, 0.12 %), epidural hematoma (two patients, 0.12%), failed aneurysm clipping (two patients, 0.12 %) and other causes (two patients, 0.12 %). Annual reexploration incidence rates ranged from 0 to 3.1 %. Annual incidence rates gradually decreased following the introduction of several intraoperative monitoring systems.

Conclusions Precise surgical planning and careful operative techniques can reduce the incidence of unplanned reexploration of the craniotomy. The introduction of various intraoperative monitoring systems can also contribute to a reduction in this incidence.

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Pre- and postoptic subdivisions of the anterior choroidal artery

AChA Anatomy

J Neurosurg 120:1217–1228, 2014

The object of this study was to delineate the microsurgical anatomy of the cisternal segment of the anterior choroidal artery (AChA). The authors also propose a new classification of this segment on the basis of its complicated course within the carotid and crural cisterns in relation to important neurovascular structures, and the site of origin, course, and areas of supply of perforating arteries.

Methods. Thirty cadaveric cerebral hemispheres injected with colored latex were dissected under surgical magnification to view the cisternal segment of the AChA and its perforators. Fiber dissections using the Klingler technique were performed in two additional latex injected hemispheres to follow the penetration points, courses, and terminal areas of supply of perforating branches that arise from the cisternal segment of the AChA.

Results. The cisternal segment of the AChA was divided into pre- and postoptic parts that meet at the artery’s genu, the most medial extension point of the cisternal segment where the artery makes an abrupt turn after passing under the optic tract. The preoptic part of the AChA extended from its origin at the inferomedial side of the internal carotid artery to the artery’s genu, which is commonly located just inferomedial to the initial part of the optic tract. The postoptic part coursed within the crural cistern and extended from the genu to the inferior choroidal point. The genu of the AChA was 8 mm medial to the artery’s origin and was located medial to the optic tract in 13% of the hemispheres. The postoptic part was longer than the preoptic part in all hemispheres and had more perforating arteries supplying critical deep structures (preoptic 3.4 per hemisphere vs postoptic 4.6 per hemisphere), and these results were statistically significant (p = 0.01). At the preoptic part, perforating arteries arose from the superolateral portion of the artery and coursed laterally; at the postoptic part, perforators arose from the inferomedial portion of the artery and coursed medially. Perforating arteries from both segments passed most commonly to the optic tract, followed by the anterior segment and apex of uncus in the preoptic part and the cerebral peduncle in the postoptic part.

Conclusions. Both parts of the cisternal segment of the AChA come into surgical view during surgeries for different pathologies in and around the perimesencephalic cisterns. However, attending to the artery’s genu and defining pre- and postoptic parts during surgery may help the surgeon locate the origin and eventual course of these perforators, and even estimate the terminal areas of supply of most of the perforating arteries. The proposed classification system can prove helpful in planning any operative procedure along the crural cistern and may reduce the probability of inadvertent injury to perforating branches of the cisternal segment.

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Stereotactic radiosurgery for Spetzler-Martin Grade III arteriovenous malformations

Spetzler-Martin grade III AVMs

J Neurosurg 120:973–981, 2014

The purpose of this study was to define the outcomes and risks of stereotactic radiosurgery (SRS) for Spetzler-Martin (SM) Grade III arteriovenous malformations (AVMs).

Methods. Between 1987 and 2009, SRS was performed in 474 patients with SM Grade III AVMs. The AVMs were categorized by scoring the size (S), drainage (D), and location (L): IIIa was a small AVM (S1D1L1, N = 282); IIIb was a medium/deep AVM (S2D1L0, N = 44); and IIIc was a medium/eloquent AVM (S2D0L1, N = 148). The median target volume was 3.8 ml (range 0.1–26.3 ml) and the margin dose was 20 Gy (range 13–25 Gy). Eighty-one patients (17%) underwent prior embolization, and 58 (12%) underwent prior resection.

Results. At a mean follow-up of 89 months, the total obliteration rates documented by angiography or MRI for all SM Grade III AVMs increased from 48% at 3 years to 69% at 4 years, 72% at 5 years, and 77% at 10 years. The SM Grade IIIa AVMs were more likely to obliterate than other subgroups. The cumulative rate of hemorrhage was 2.3% at 1 year, 4.4% at 2 years, 5.5% at 3 years, 6.4% at 5 years, and 9% at 10 years. The SM Grade IIIb AVMs had a significantly higher cumulative rate of hemorrhage. Symptomatic adverse radiation effects were detected in 6%.

Conclusions. Treatment with SRS was an effective and relatively safe management option for SM Grade III AVMs. Although patients with residual AVMs remained at risk for hemorrhage during the latency interval, the cumulative 10-year 9% hemorrhage risk in this series may represent a significant reduction compared with the expected natural history.

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Spinal juvenile (Type III) extradural-intradural arteriovenous malformations

Spinal extradural-intradural AVMs

 J Neurosurg Spine 20:452–458, 2014

Owing to their rarity, demographics, natural history, and treatment, results for spinal juvenile (Type III) extradural-intradural arteriovenous malformations (AVMs) are frequently only provided in case report format.

Methods. A pooled analysis was performed utilizing the PubMed database through April 2013. Individualized patient data were extracted to elucidate demographics, hemorrhage risk, and treatment result information.

Results. Twenty-nine studies describing 51 patients were included. The mean age at presentation was 15.0 ± 10.5 years with a slight male predilection (63%, 1.7:1 sex ratio). Presentation modality included progressive deficits in 35%, hemorrhage in 31%, acute deficits not attributed to hemorrhage in 22%, and asymptomatic/incidental in 12% of patients. The annual hemorrhage rate was 2.1%; statistically significant risk factors for hemorrhage included presentation age (HR 0.39 [95% CI 0.18–0.87]) and associated aneurysms (HR 8.74 [95% CI 1.76–43.31]). Seventy-seven percent of patients underwent treatment; after a mean follow-up of 2.6 ± 3.2 years, 73% were improved, 10% were the same, and 17% were worse neurologically. Of 25 cases with described angiographic results, 8 lesions were obliterated (32%). Of these 25 patients, 8 had AVMs with associated aneurysms, and the aneurysm was obliterated in all 8 patients. Over the course of 57.9 patient-years of follow-up, including 55.3 patient-years for partially treated AVMs, no hemorrhages were described, reflecting a trend toward protection from hemorrhage after treatment (p = 0.12, likelihood ratio test).

Conclusions. Spinal juvenile (Type III) extradural-intradural AVMs commonly present symptomatically. Associated arterial aneurysms increase their hemorrhage risk, and protection from hemorrhage may be achieved from partial obliteration of these lesions, particularly if targeted toward associated aneurysms.

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Radiosurgery for Spetzler-Martin Grade III arteriovenous malformations

Multimodality management of Spetzler-Martin Grade III arteriovenous malformations

J Neurosurg 120:959–969, 2014

Intracranial arteriovenous malformations (AVMs) are most commonly classified based on their Spetzler- Martin grades. Due to the composition of the Spetzler-Martin grading scale, Grade III AVMs are the most heterogeneous, comprising 4 distinct lesion subtypes. The management of this class of AVMs and the optimal treatment approach when intervention is indicated remain controversial. The authors report their experience with radiosurgery for the treatment of Grade III AVMs in a large cohort of patients.

Methods. All patients with Spetzler-Martin Grade III AVMs treated with radiosurgery at the University of Virginia over the 20-year span from 1989 to 2009 were identified. Patients who had less than 2 years of radiological follow-up and did not have evidence of complete obliteration during that period were excluded from the study, leaving 398 cases for analysis. The median patient age at treatment was 31 years. The most common presenting symptoms were hemorrhage (59%), seizure (20%), and headache (10%). The median AVM volume was 2.8 cm3, and the median prescription dose was 20 Gy. The median radiological and clinical follow-up intervals were 54 and 68 months, respectively. Univariate and multivariate Cox proportional hazards and logistic regression analysis were used to identify factors associated with obliteration, postradiosurgery radiation-induced changes (RIC), and favorable outcome.

Results. Complete AVM obliteration was observed in 69% of Grade III AVM cases at a median time of 46 months after radiosurgery. The actuarial obliteration rates at 3 and 5 years were 38% and 60%, respectively. The obliteration rate was higher in ruptured AVMs than in unruptured ones (p < 0.001). Additionally, the obliteration rate for Grade III AVMs with small size (< 3 cm diameter), deep venous drainage, and location in eloquent cortex was higher than for the other subtypes (p < 0.001). Preradiosurgery AVM rupture (p = 0.016), no preradiosurgery embolization (p = 0.003), increased prescription dose (p < 0.001), fewer isocenters (p = 0.006), and a single draining vein (p = 0.018) were independent predictors of obliteration. The annual risk of postradiosurgery hemorrhage during the latency period was 1.7%. Two patients (0.5%) died of hemorrhage during the radiosurgical latency period. The rates of symptomatic and permanent RIC were 12% and 4%, respectively. Absence of preradiosurgery AVM rupture (p < 0.001) and presence of a single draining vein (p < 0.001) were independent predictors of RIC. Favorable outcome was observed in 63% of patients. Independent predictors of favorable outcome were no preradiosurgery hemorrhage (p = 0.014), increased prescription dose (p < 0.001), fewer isocenters (p = 0.014), deep location (p = 0.014), single draining vein (p = 0.001), and lower Virginia radiosurgery AVM scale score (p = 0.016).

Conclusions. Radiosurgery for Spetzler-Martin Grade III AVMs yields relatively high rates of obliteration with a low rate of adverse procedural events. Small and ruptured lesions are more likely to become obliterated after radiosurgery than large and unruptured ones.

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Clipping of UIA and postoperative cognition

MCA aneurysm

J Neurosurg 120:937–944, 2014

The mechanisms underlying neurocognitive changes after surgical clipping of unruptured intracranial aneurysms (UIAs) are poorly understood. The aim of this study was to investigate factors that determine postoperative cognitive decline after UIA surgery.

Methods. Data from 109 patients who underwent surgical clipping of a UIA were retrospectively evaluated. These patients underwent neuropsychological examinations (NPEs), including assessment by the Wechsler Adult Intelligence Scale- Third Edition and the Wechsler Memory Scale-Revised before and 6 months after surgical clipping of the UIA. Results of NPEs were converted into z scores, from which pre- and postoperative cognitive composite scores (CSpre and CSpost) were obtained. The association between the change in CS between pre- and postoperative NPEs (that is, CSpost – CSpre [CSpost – pre]) and various variables was assessed. These latter variables included surgical approach (anterior interhemispheric approach or other approach), structural change evidenced on T2-weighted imaging at 6 months, somatosensory evoked potential amplitude decrease greater than 50% during aneurysm manipulation, preexisting multiple ischemic lesions in the lacunar region detected on preoperative T2-weighted imaging, and total microsurgical time. Paired t-tests of the NPE scores were performed to determine the net effect of these factors on neurocognitive function at 6 months.

Results. A significant CSpost – pre decrease was observed in patients with a structural change on postoperative T2-weighted imaging when compared with those without such a change on postoperative T2-weighted imaging (-0.181 vs 0.043, p = 0.012). Multiple regression analysis demonstrated that postoperative T2-weighted imaging change independently and negatively correlated with CSpost – pre (p = 0.0005). In group-rate analysis, postoperative NPE scores were significantly improved relative to preoperative scores.

Conclusions. Minimal structural damage visualized on T2-weighted images at 6 months as a result of factors such as pial/microvascular injury and excessive retraction during surgical manipulation could cause subtle but significant negative effects on postoperative neurocognitive function after surgical clipping of a UIA. However, this detrimental effect was small, and based on the group-rate analysis, the authors conclude that successful and meticulous surgical clipping of a UIA does not adversely affect postoperative cognitive function.

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Flexible Omnidirectional Carbon Dioxide Laser as an Effective Tool for Resection of Brainstem, Supratentorial, and Intramedullary Cavernous Malformations

Ponto-mesencephalic cavernoma

Operative Neurosurgery 10:34–45, 2014

Lasers have a long history in neurosurgery, yet bulky designs and difficult ergonomics limit their use. With its ease of manipulation and multiple applications, the OmniGuide CO2 laser has reintroduced laser technology to the microsurgical resection of brain and spine lesions. This laser, delivered through a hollow-core fiber lined with a unidirectional mirror, minimizes energy loss and allows precise targeting.

OBJECTIVE: To analyze resections performed by the senior author from April 2009 to March 2013 of 58 cavernous malformations (CMs) in the brain and spine with the use of the OmniGuide CO2 laser, to reflect on lessons learned from laser use in eloquent areas, and to share data on comparisons of laser power calibration and histopathology.

METHODS: Data were collected from electronic medical records, radiology reports, operative room records, OmniGuide CO2 laser case logs, and pathology records.

RESULTS: Of 58 CMs, approximately 50% were in the brainstem (30) and the rest were in supratentorial (26) and intramedullary spinal locations (2). Fifty-seven, ranging from 5 to 45 mm, were resected, with a subtotal resection in 1. Laser power ranged from 2 to 10 W. Pathology specimens showed minimal thermal damage compared with traditionally resected specimens with bipolar coagulation.

CONCLUSION: The OmniGuide CO2 laser is safe and has excellent precision for the resection of supratentorial, brainstem, and spinal intramedullary CMs. No laser-associated complications occurred, and very low energy was used to dissect malformations from their surrounding hemosiderin-stained parenchymas. The authors recommend its use for deep-seated and critically located CMs, along with traditional tools.

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Minimally invasive microsurgery for anterior circulation aneurysms

MIS for Anterior Circulation Aneurysms

Acta Neurochir (2014) 156:493–503

The aim of our study was to evaluate minimally invasive techniques for the treatment of anterior circulation aneurysms versus standard surgery, and to calculate the impact of these techniques on health resources, length of stay, and treatment costs.

Methods A consecutive series of 24 patients with ruptured and 30 with unruptured anterior circulation aneurysms treated with minimally invasive microsurgery (MIM) by the same surgeon was compared with a matched series of standard microsurgeries (SM) conducted for 23 ruptured and 22 unruptured aneurysms. Complication rates, aneurysm obliteration, modified Rankin Scale (mRS) outcomes, length of stay, and treatment costs were assessed.

Results Surgical complications, aneurysm obliteration rates and mRS outcomes were comparable between MIM and SM groups in ruptured and unruptured aneurysm cohorts. MIM resulted in shorter operative times both in unruptured (102.7±4.35 vs 194.7±10.26 min, p<0.0001) and ruptured aneurysms (124.3±827 vs 209±13.84 min, p<0.0001). Length of stay was reduced in patients with MIM for unruptured aneurysms (1.55±24 vs 4.28±0.71 days, p<0.000,1) but not in those with ruptured aneurysms. MIM reduced treatment costs of unruptured aneurysm patients, mainly through reduced utilization of inpatient resources (non-acute bed costs in CAD: 371.2±80.99 vs 1440±224.1, p<0.0001), whereas costs were comparable in patients with ruptured aneurysms.

Conclusion Minimally invasive surgery is a safe and effective approach for the treatment of ruptured and unruptured aneurysms of the anterior circulation. In patients with unruptured aneurysms, reduced invasiveness and shorter operative times decreased length of stay, which reflects improved patient postoperative recovery. Overall, this translated into bed resource economy and cost reduction.

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Middle Cerebral Artery Bifurcation Aneurysms: An Anatomic Classification Scheme for Planning Optimal Surgical Strategies

Middle Cerebral Artery Bifurcation Aneurysms- An Anatomic Classification Scheme for Planning Optimal Surgical Strategies

Operative Neurosurgery 10:145–155, 2014

Changing landscapes in neurosurgical training and increasing use of endovascular therapy have led to decreasing exposure in open cerebrovascular neurosurgery. To ensure the effective transition of medical students into competent practitioners, new training paradigms must be developed.

OBJECTIVE: Using principles of pattern recognition, we created a classification scheme for middle cerebral artery (MCA) bifurcation aneurysms that allows their categorization into a small number of shape pattern groups.

METHODS: Angiographic data from patients with MCA aneurysms between 1995 and 2012 were used to construct 3-dimensional models. Models were then analyzed and compared objectively by assessing the relationship between the aneurysm sac, parent vessel, and branch vessels. Aneurysms were then grouped on the basis of the similarity of their shape patterns in such a way that the in-class similarities were maximized while the total number of categories was minimized. For each category, a proposed clip strategy was developed.

RESULTS: From the analysis of 61 MCA bifurcation aneurysms, 4 shape pattern categories were created that allowed the classification of 56 aneurysms (91.8%). The number of aneurysms allotted to each shape cluster was 10 (16.4%) in category 1, 24 (39.3%) in category 2, 7 (11.5%) in category 3, and 15 (24.6%) in category 4.

CONCLUSION: This study demonstrates that through the use of anatomic visual cues, MCA bifurcation aneurysms can be grouped into a small number of shape patterns with an associated clip solution. Implementing these principles within current neurosurgery training paradigms can provide a tool that allows more efficient transition from novice to cerebrovascular expert.

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Extended Subtemporal Transtentorial Approach to the Anterior Incisural Space and Upper Clival Region: Experience With Posterior Circulation Aneurysms

Extended Subtemporal Transtentorial Approach to the Anterior Incisural Space and Upper Clival Region- Experience With Posterior Circulation Aneurysms

Neurosurgery 10:15–24, 2014

Although most posterior circulation aneurysms are currently treated by endovascular means, some are not amenable to this treatment modality. The narrow working window afforded by the anterolateral and lateral surgical approaches often translates into suboptimal visualization and limited maneuverability.

OBJECTIVE: We present a modified technique of tentorial incision and reflection that optimizes the exposure achieved with the traditional subtemporal approach and report our clinical experience in a series of posterior circulation aneurysms.

METHODS: Retrospective review of patients operated via an extended subtemporal transtentorial approach for posterior circulation aneurysms. The modified tentorial incision implies dissection of the trochlear nerve along its dural canal up to its entrance into the cavernous sinus and incision of a tentorial flap that extends up to Meckel cave, which is then reflected far anterolaterally. Clinical and radiological data were reviewed.

RESULTS: This series comprises 18 patients (21 procedures). Ten patients presented (56%) with a subarachnoid hemorrhage. Aneurysms most frequently arose from the basilar tip (61%) and were of small size (50%) and saccular morphology (72%). Two patients underwent surgery following unsuccessful endovascular treatment. Aneurysm treatment was successful on the first attempt in 90% (19/21) and after a second attempt in 10% (2/21). Documented postoperative palsies of the oculomotor (n = 3) and trochlear (n = 1) nerves were all transient. No procedure-related mortality occurred.

CONCLUSION: This modified technique of tentorial incision and reflection optimizes visibility, anatomic orientation, and maneuverability by increasing the rostrocaudal and anterolateral exposure obtained via the extended subtemporal transtentorial route without permanent postoperative trochlear nerve deficit.

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Stereotactic radiosurgery for arteriovenous malformations of the cerebellum

Bowden et al

J Neurosurg 120:583–590, 2014

Arteriovenous malformations (AVMs) of the posterior fossa have an aggressive natural history and propensity for hemorrhage. Although the cerebellum accounts for the majority of the posterior fossa volume, there is a paucity of stereotactic radiosurgery (SRS) outcome data for AVMs of this region. The authors sought to evaluate the long-term outcomes and risks of cerebellar AVM radiosurgery.

Methods. This single-institution retrospective analysis reviewed the authors’ experience with Gamma Knife surgery during the period 1987–2007. During this time 64 patients (median age 47 years, range 8–75 years) underwent SRS for a cerebellar AVM. Forty-seven patients (73%) presented with an intracranial hemorrhage. The median target volume was 3.85 cm3 (range 0.2–12.5 cm3), and the median marginal dose was 21 Gy (range 15–25 Gy).

Results. Arteriovenous malformation obliteration was confirmed by MRI or angiography in 40 patients at a median follow-up of 73 months (range 4–255 months). The actuarial rates of total obliteration were 53% at 3 years, 69% at 4 years, and 76% at 5 and 10 years. Elevated obliteration rates were statistically higher in patients who underwent AVM SRS without prior embolization (p = 0.005). A smaller AVM volume was also associated with a higher rate of obliteration (p = 0.03). Four patients (6%) sustained a hemorrhage during the latency period and 3 died. The cumulative rates of AVM hemorrhage after SRS were 6% at 1, 5, and 10 years. This correlated with an overall annual hemorrhage rate of 2.0% during the latency interval. One patient experienced a hemorrhage 9 years after confirmed MRI and angiographic obliteration. A permanent neurological deficit due to adverse radiation effects developed in 1 patient (1.6%) and temporary complications were seen in 2 additional patients (3.1%).

Conclusions. Stereotactic radiosurgery proved to be most effective for patients with smaller and previously nonembolized cerebellar malformations. Hemorrhage during the latency period occurred at a rate of 2.0% per year until obliteration occurred.

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Analysis of the relationship between different bleeding positions on intraoperative rupture anterior circulation aneurysm and surgical treatment outcome

Intraoperative rupture anterior circulation aneurrysms

Acta Neurochir (2014) 156:481–491

It is well recognized that intraoperative aneurysm rupture (IAR) is a serious event that is difficult to manage and has a relatively serious influence on a patient’s prognosis. The aim of this study was to evaluate the prognostic value of different bleeding positions of IAR in patients, and to describe the technique that the authors have used to clip the ruptured aneurysms.

Methods From May 2009 to March 2012, a total of 148 aneurysms in 135 consecutive patients in our institution underwent clipping surgeries, and 31 IARs occurred in 30 patients. The clinical data of all patients were retrospectively analyzed. Statistics analysis was performed to analyze possible factors of different bleeding positions of IARs, to assist observation.

Results Outcome was estimated by Glasgow outcome scale via following up or calling back within 1, 3, and 6 months after surgery: 94 patients were 5’, 23 patients were 4’, nine patients were 3’, two patients were 2’ and eight patients were 1’. There was no significant difference between the outcome of IAR and that of no intraoperative aneurysm rupture (NIAR) in Hunt–Hess groups 0–III (P =0.802) and Hunt–Hess groups IV–V (P =0.229), and the different bleeding positions were shown to be an important factor that significantly influences the patients’ prognosis (P=0.001).

Conclusions Different bleeding positions of IAR have a significant impact on surgical outcome; IAR of the neck is the most devastating complication. If surgeons take appropriate measures according to different bleeding positions, the efficiency, accuracy and security of the operation will be improved

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A prospective study of microscope-integrated intraoperative fluorescein videoangiography during arteriovenous malformation surgery

intraoperative fluorescein videoangiography during arteriovenous malformation surgery

Neurosurg Focus 36 (2):E15, 2014

The authors report on the use of a recently developed microscope-integrated fluorescent module using low-dose intravenous fluorescein for videoangiography during arteriovenous malformation (AVM) surgery.

Methods. The authors analyzed the application of a low-dose intraoperative fluorescein in 4 consecutive patients undergoing AVM surgery. The ability to distinguish the associated vessels of the AVM from normal vessels and to assess the degree of AVM obliteration based on videoangiography of venous drainage was specifically analyzed.

Results. All 4 patients underwent fluorescein angiography without complication. In each case, videoangiography confirmed recognition of feeding arteries and draining veins through the operating oculars under the fluorescent mode. In one case involving a large frontal AVM, videoangiography demonstrated mainly cortical veins on the surface of the AVM and alerted the senior author to first tackle the feeding arteries in the interhemispheric space. While evaluating the flow within the different draining veins after most of the AVM was disconnected, videoangiography also prioritized the order for disconnection of large draining veins to allow mobilization the AVM and exposure of the remaining deep arterial feeders. In the other 3 cases, videoangiography allowed easy recognition of the angioarchitecture of the AVMs, estimated its cortical boundaries, and most importantly, assessed the flow within the draining veins before their disconnection.

Conclusions. The authors found fluorescein videoangiography to be a useful adjunct in resection of AVMs. This technology offers the unique ability to visualize fluorescent vessels and nonfluorescent tissues in near-natural colors simultaneously and permits microsurgical manipulation of relevant structures under the fluorescent mode. Largerscale studies are needed to establish its efficacy and wider applicability.

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