Spinal Pial (Type IV) Arteriovenous Fistulae

Spinal Pial (Type IV) Arteriovenous Fistulae

Neurosurgery 73:141–151, 2013

Demographics, hemorrhage risk, and results of surgical and endovascular treatment of spinal pial (type IV) arteriovenous fistulae (AVFs) across a large patient group have not been previously reported.

OBJECTIVE: To report demographics, hemorrhage rates, and treatment results for these AVFs.

METHODS: We performed a pooled analysis via the PubMed and Embase databases through November 2012. Individualized patient data were extracted and analyzed using Cox proportional hazards regression to obtain hazard ratios for hemorrhage risk factors and pooled for baseline demographics and treatment results.

RESULTS: We extracted information on 213 patients from 28 studies. Only 1% of lesions were incidental; 93% of patients presented with neurologic deficits and 36% with hemorrhage. Patients with type IVa lesions were significantly older (mean age, 46.9 years) and demonstrated a male sex predilection (68% male). Patients with type IVc lesions were significantly younger (mean age, 18.7 years), had no sex predilection, and had the highest prevalence of syndromic conditions (29% of cases). The annual hemorrhage rate was 2.5% (95% confidence interval [CI]: 1.4%-4.7%), increasing to 5.6% for hemorrhagic fistulae (95% CI: 3.0%-10.7%; hazard ratio: 6.31; 95% CI: 0.69-57.4; P = .10). Patient sex, fistula location, and fistula subclass were not significant risk factors for hemorrhage. The surgical obliteration rate was 88%; 68% of patients improved, 26% were the same, and 6% were worse. The endovascular obliteration rate was 74%; 75% of patients improved, 14% were the same, and 11% were worse.

CONCLUSION: We demonstrate the utility of the Anson-Spetzler a-c subclassification and underscore the efficacy of surgical and endovascular spinal AVF treatment.

Risk Factors for Pediatric Arachnoid Cyst Rupture/Hemorrhage: A Case-Control Study

Risk_Factors_for_Pediatric_Arachnoid_Cyst

As the availability of imaging modalities has increased, the finding of arachnoid cysts has become common. Accurate patient counseling regarding physical activity or risk factors for cyst rupture or hemorrhage has been hampered by the lack of definitive association studies.

OBJECTIVE: This case-control study evaluated factors that are associated with arachnoid cyst rupture (intracystic hemorrhage, adjacent subdural hematoma, or adjacent subdural hygroma) in pediatric patients with previously asymptomatic arachnoid cysts.

METHODS: Patients with arachnoid cysts and intracystic hemorrhage, adjacent subdural hygroma, or adjacent subdural hematoma treated at a single institution from 2005 to 2010 were retrospectively identified. Two unruptured/nonhemorrhagic controls were matched to each case based on patient age, sex, anatomical cyst location, and side. Risk factors evaluated included arachnoid cyst size, recent history of head trauma, and altitude at residence.

RESULTS: The proportion of imaged arachnoid cysts that presented either originally or subsequently with a rupture or hemorrhage was 6.0%. Larger cyst size, as defined by maximal cyst diameter, was significantly associated with cyst rupture/hemorrhage (P < .001). When dichotomized with a 5-cm cutoff, 9/13 larger cysts ruptured and/or hemorrhaged, whereas only 5/29 smaller cysts ruptured/hemorrhaged (odds ratio = 16.5 (confidence interval [2.5, N]). A recent history of head trauma was also significantly associated with the outcome (P < .001; odds ratio = 25.1 (confidence interval [4.0, N]). Altitude was not associated with arachnoid cyst rupture or hemorrhage.

CONCLUSION: This case-control study suggests that larger arachnoid cyst size and recent head trauma are risk factors for symptomatic arachnoid cyst rupture/hemorrhage.

Risk of hemorrhage from de novo cerebral aneurysms

denovo aneurysms

J Neurosurg 118:58–62, 2013

A small percentage of patients will develop a completely new or de novo aneurysm after discovery of an initial aneurysm. The natural history of these lesions is unknown. The authors undertook this statistical evaluation a large cohort of patients with both ruptured and unruptured de novo aneurysms with the aim of analyzing risk factors for rupture and estimating a risk of subarachnoid hemorrhage (SAH).

Methods. A review of a prospectively maintained database of all aneurysm patients treated by the vascular neurosurgery service of Goodman Campbell Brain and Spine from 1976–2010 was performed. Of the 4718 patients, 611 (13%) had longterm follow-up imaging. The authors identified 27 patients (4.4%) with a total of 32 unruptured de novo aneurysms from routine surveillance imaging. They identified another 10 patients who presented with a new SAH from a de novo aneurysm after treatment of their original aneurysm. The total study group was thus 37 patients with a total of 42 de novo aneurysms. The authors then compared the 27 patients with incidentally discovered aneurysms with the 10 patients with SAH. A statistical analysis was performed, comparing the 2 groups with respect to patient and aneurysm characteristics and risk factors.

Results. Thirty-seven patients were identified as having true de novo aneurysms. This group had a female predominance and a high percentage of smokers. These 37 patients had a total of 42 de novo aneurysms. Ten of these 42 aneurysms hemorrhaged. De novo aneurysms in both the SAH and non-SAH group were anatomically small (< 10 mm). The estimated risk of hemorrhage over 5 years was 14.5%, higher than the expected SAH risk of small, unruptured aneurysms reported in the ISUIA (International Study of Unruptured Intracranial Aneurysms) trial. There was no statistically significant correlation between hemorrhage and any of the following risk factors: hypertension, diabetes, tobacco and alcohol use, polycystic kidney disease, or previous SAH. There was a statistically significant between-groups difference with respect to patient age, with the mean patient age being significantly older in the SAH aneurysm group than in the non-SAH group (p = 0.047). This is likely reflective of longer follow-up and discovery time, as the mean length of time between initial treatment and discovery of the de novo aneurysm was longer in the SAH group (p = 0.011).

Conclusions. While rare, de novo aneurysms may have a risk for SAH that is comparatively higher than the risk associated with similarly sized, small, initially discovered unruptured saccular aneurysms. The authors therefore recommend longterm follow-up for all patients with aneurysms, and they consider a more aggressive treatment strategy for de novo aneurysms than for incidentally discovered initial aneurysms.

Spinal Glomus (Type II) Arteriovenous Malformations

Spinal Glomus (Type II) AVM

Neurosurgery 72:25–32, 2013

The natural history and treatment results for spinal glomus (type II) arteriovenous malformations (AVMs) remain relatively obscure.

OBJECTIVE: To calculate spinal glomus (type II) AVM hemorrhages rates and amalgamate results of intervention.

METHODS: We performed a pooled analysis via the PubMed database through May 2012, including studies with at least 3 cases. Data on individual patients were extracted and analyzed using a Cox proportional hazards regression model to obtain hazard ratios for hemorrhage risk factors.

RESULTS: The annual hemorrhage rate before treatment was 4% (95% confidence interval [confidence interval]: 3%-6%), increasing to 10% (95% CI: 7%-16%) for AVMs with previous hemorrhage. The hazard ratio for hemorrhage after hemorrhagic presentation was 2.25 (95% CI: 0.71-7.07), increasing to 13.0 within the first 10 years (95% CI: 1.44-118). The overall rates of complete obliteration were 78% (95% CI: 72%-83%) for surgery and 33% (95% CI: 24%-43%) for endovascular treatment. Long-term clinical worsening occurred in 12% of patients after surgical treatment (95% CI: 8%-16%) and in 13% after endovascular treatment (95% CI: 7%-21%). No hemorrhages occurred after complete obliteration. After partial surgical treatment, the annual hemorrhage rate was 3% (95% CI: 1%-6%); no hemorrhages were reported over 196 patient-years after partial endovascular treatment.

CONCLUSION: Spinal glomus (type II) AVMs with previous hemorrhage, particularly within 10 years, demonstrated a greater risk of hemorrhage. Complete obliteration and even partial endovascular treatment significantly decreased their hemorrhage rate.

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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.

Hemorrhage From Arteriovenous Malformations During Pregnancy

Neurosurgery 71:349–356, 2012 DOI: 10.1227/NEU.0b013e318256c34b

Previous hemorrhage, deep venous drainage, and deep location are established risk factors for arteriovenous malformation (AVM) hemorrhage. Although pregnancy is an assumed risk factor, there is a relative paucity of data to support this neurosurgical tenet.

OBJECTIVE: To elucidate the hemorrhage rate of AVMs during pregnancy.

METHODS: We reviewed the records of 54 women with an angiographic diagnosis of an AVM at our institution. Annual hemorrhage rates were calculated as the ratio of the number of bleeds to total number of patient-years of follow-up. Patient-years of followup were tallied assuming lesion presence from birth until AVM obliteration. The Cox proportional hazards model for hemorrhage with pregnancy as the time-dependent variable was used to calculate the hazard ratio.

RESULTS: Five hemorrhages in 4 patients occurred over 62 pregnancies, yielding a hemorrhage rate of 8.1% per pregnancy or 10.8% per year. Over the remaining 2461.3 patient-years of follow-up, only 28 hemorrhages occurred, yielding an annual hemorrhage rate of 1.1%. The hazard ratio for hemorrhage during pregnancy was 7.91 (P = 2.23 x 10-4), increasing to 18.12 (P = 7.31 x 10-5) when limiting the analysis to patient follow-up up to age 40.

CONCLUSION: Because of the increased risk of hemorrhage from AVMs during pregnancy, we recommend intervention in women who desire to bear children, particularly if the AVM has bled. If the AVM is discovered during pregnancy, we recommend early intervention if it has ruptured; if it is unruptured, we recommend comprehensive counseling, weighing risks of intervention against continuation of pregnancy without intervention.

 

Injuries of the Cingulum and Fornix After Rupture of an Anterior Communicating Artery Aneurysm

Neurosurgery 70:819–823, 2012 DOI: 10.1227/NEU.0b013e3182367124 

After rupture of an anterior communicating artery (ACoA) aneurysm, the anterior cingulum and the fornix can be vulnerable to injury. However, very little is known about this topic.

OBJECTIVE: To investigate injuries of the cingulum and fornix in patients with an ACoA aneurysm rupture with diffusion tensor tractography.

METHODS: Eleven consecutive patients with an ACoA aneurysm rupture and 11 ageand sex-matched normal control subjects were recruited. Diffusion tensor imaging was scanned at an average of 54.1 days (range, 29-97 days) after onset of ACoA aneurysm rupture.

RESULTS: We found that 6 (54.5%) and 7 (63.6%) of 11 patients revealed no trajectory of the anterior cingulum and the fornical body on diffusion tensor tractography, respectively. In terms of diffusion tensor imaging parameters, we found that the fractional anisotropy value and tract volume of the cingulum and fornix were decreased (P , .05) and that mean diffusivity values were increased (P , .05), except for those of the left fornix, which showed no difference (P . .05).

CONCLUSION: We found injuries of the cingulum and fornix in patients with an ACoA aneurysm rupture. It is our belief that sustained memory impairment of patients with an ACoA aneurysm rupture might be related to injury of the cingulum and fornix. Therefore, we recommend evaluation of the cingulum and fornix with diffusion tensor tractography for patients with an ACoA aneurysm rupture.

The Natural History of Cranial Dural Arteriovenous Fistulae With Cortical Venous Reflux—The Significance of Venous Ectasia

Neurosurgery 70:312–319, 2012 DOI: 10.1227/NEU.0b013e318230966f

The quoted risk of hemorrhage from dural arteriovenous fistulae with cortical venous reflux varies widely, and the influence of angiographic grade on clinical course has not previously been reported.

OBJECTIVE: To assess the risk of hemorrhage and the influence of angiographic grade on this risk, compared with known predictors of hemorrhage such as presentation.

METHODS: Seventy-five fistulae with cortical venous reflux identified in our arteriovenous malformations clinic between 1992 and 2007 were followed up clinically, and their angiograms were reviewed.

RESULTS: There were 8 hemorrhages in 90 years of follow-up. The annual incidence of hemorrhage before any treatment was 13%, and 4.7% after partial treatment, giving an overall incidence of 8.9% before definitive treatment. Borden and Cognard grades were poor discriminators of risk for lesions with the exception of Cognard type IV lesions. These lesions, characterized by venous ectasia, had a 7-fold increase in the incidence of hemorrhage (3.5% no ectasia vs 27% with ectasia). Patients presenting with hemorrhage (20%) or nonhemorrhagic neurological deficit (22%) had a higher incidence of hemorrhage than those with a benign presentation (4.3%), but this may be directly linked to the presence of venous ectasia.

CONCLUSION: In this series untreated dural arteriovenous fistulae with cortical venous reflux had a 13% annual incidence of hemorrhage after diagnosis. There was a significant difference between those with and without venous ectasia. This should be confirmed by further studies, but probably defines a high-risk subgroup of patients that requires rapid intervention.

Meta-Analysis of Hemorrhagic Complications From Ventriculostomy Placement by Neurosurgeons

Neurosurgery 69:255–260, 2011 DOI: 10.1227/NEU.0b013e31821a45ba

Ventriculostomy placement is an important diagnostic and therapeutic tool for neurosurgeons. Multiple authors have presented retrospective series of patients evaluating periprocedure hemorrhage.

OBJECTIVE: We performed a meta-analysis of existing studies to determine a more accurate rate of hemorrhage.

METHODS: A MEDLINE and PubMed search was performed to find all studies of 25 or more patients conducted since 1970 that found a hemorrhagic complication rate from placement of a ventriculostomy. Studies in which a non-neurosurgeon placed the ventriculostomy and studies involving premature infants were excluded.

RESULTS: Sixteen studies were used to obtain data from 2428 ventriculostomy procedures. Hemorrhage was found after 203 procedures, and 52 of these hemorrhages were deemed significant by the authors. The cumulative rate of hemorrhage was 7.0% (95% confidence interval: 4.5%-9.4%), with P , .05. The cumulative rate of significant hemorrhage was 0.8% (95% confidence interval: 0.2%-1.4%) with P , .05.

CONCLUSION: Based on our meta-analysis, the overall hemorrhagic complication rate from ventriculostomy placement by neurosurgeons is approximately 7%. The rate of significant hemorrhage from ventriculostomy placement is approximately 0.8%. Further prospective studies are warranted to better address this question.

The natural history of intracranial cavernous malformations

Neurosurg Focus 30 (6):E24, 2011, DOI: 10.3171/2011.3.FOCUS1165

Literature reports on the natural history of cerebral cavernous malformations (CMs) are numerous, with considerable variability in lesion epidemiology, hemorrhage rates, and risk factors for hemorrhage.

In this review, the authors performed a meta-analysis of 11 natural history studies. The overall male-to-female ratio was 1:1, and the mean age at presentation was 30.6 years. Overall, 37% of patients presented with seizures, 36% with hemorrhage, 23% with headaches, 22% with focal neurological deficits, and 10% were asymptomatic. Some patients had more than one symptom. Seizure presentation was most prevalent among supratentorial CMs, while focal neurological deficits were common in patients with infratentorial CMs. By location, CMs were in the cerebral hemispheres (66%), brainstem (18%), basal ganglia or thalamus (8%), cerebellum (6%), and other (2.5% [combined supra- and infratentorial, callosal or insular]). Overall, 19% of patients harbored multiple intracranial CMs, and 9% had radiographically apparent associated developmental venous anomalies. An overall annual hemorrhage rate of 2.4% per patient-year (range 1.6%–3.1%) was identified across 3 studies.

Prior hemorrhage and female sex were risk factors for bleeding, while CM size and multiplicity did not affect hemorrhage rates. Although not impacting the hemorrhage rate itself, deep location was a risk factor for increased clinical aggressiveness.

Risk Factors for Conversion to Permanent Ventricular Shunt in Patients Receiving Therapeutic Ventriculostomy for Traumatic Brain Injury

Neurosurgery 68:85–88, 2011 DOI: 10.1227/NEU.0b013e3181fd85f4

Intracranial pressure is routinely monitored in patients with severe traumatic brain injury (TBI). Patients with TBI sometimes develop hydrocephalus, requiring permanent cerebrospinal fluid (CSF) diversion. OBJECTIVE: To quantify the need for permanent CSF diversion in patients with TBI. METHODS: Patients who received a ventriculostomy after TBI between June 2007 and July 2008 were identified, and their medical records were abstracted to a database. RESULTS: Sixteen of 71 patients (22.5%) receiving a ventriculostomy required a ventriculoperitoneal or ventriculoatrial shunt before discharge from the hospital. The average number of days between ventriculostomy and shunt was 18.3. Characteristics that predispose these patients to require permanent CSF diversion include the need for craniotomy within 48 hours of admission (odds ratio, 5.20; 95% confidence interval, 1.48-18.35) and history of culture-positive CSF (odds ratio, 5.52; 95% confidence interval, 1.19-25.52). Length of stay was increased in patients receiving permanent CSF diversion (average length of stay, 61 vs 31 days; P = .04). Patient discharge disposition was similar between shunted and nonshunted patients. CONCLUSION: In this retrospective study, 22% of TBI patients who required a ventriculostomy eventually needed permanent CSF diversion. Patients with TBI should be assessed for the need for permanent CSF diversion before discharge from the hospital. Care must be taken to prevent ventriculitis. Future studies are needed to evaluate more thoroughly the risk factors for the need for permanent CSF diversion in this patient population.

Surgical approaches to brainstem cavernous malformations

Neurosurg Focus 29 (3):E8, 2010. DOI: 10.3171/2010.6.FOCUS10128

Brainstem cavernous malformations (CMs) are low-flow vascular lesions in eloquent locations. Their presentation is often marked with symptomatic hemorrhages that appear to occur more frequently than hemorrhage from supratentorial cavernomas.

Brainstem CMs can be removed using 1 of the 5 standard skull-base approaches: retrosigmoid, suboccipital (with or without telovelar approach), supracerebellar infratentorial, orbitozygomatic, and far lateral.

Patients being referred to a tertiary institution often have lesions that are aggressive with respect to bleeding rates. Nonetheless, the indications for surgery, in the authors’ opinion, are the same for all lesions: those that are symptomatic, those that cause mass effect, or those that abut a pial surface. Patients often have relapsing and remitting courses of symptoms, with each hemorrhage causing a progressive and stepwise decline.

Many patients experience new postoperative deficits, most of which are transient and resolve fully. Despite the risks associated with operating in this highly eloquent tissue, most patients have had favorable outcomes in the authors’ experience. Surgical treatment of brainstem CMs protects patients from the potentially devastating effects of rehemorrhage, and the authors believe that the benefits of intervention outweigh the risks in patients with the appropriate indications.

Contrast-Enhanced Magnetic Resonance Characteristics of Arteriovenous Malformations After Gamma Knife Radiosurgery: Predictors of Post-Angiographic Obliteration Hemorrhage

Neurosurgery 67:101-109, 2010 DOI: 10.1227/01.NEU.0000370601.17570.4

The reported cumulative risk of post-angiographic obliteration (post-AO) hemorrhage from arteriovenous malformations (AVMs) following gamma knife radiosurgery (GKRS) over 10 years is 2.2%.

OBJECTIVE: To identify the warning signs of post-AO hemorrhage by analyzing the characteristics of enhancement on contrast-enhanced MRI magnetic resonance imaging (MRI) of AVMs with post-AO hemorrhage.

METHODS:We performed a retrospective analysis of 121 patients whose AVMs were angiographically obliterated within 5 years of GKRS without hemorrhage and who received at least 1 contrast-enhanced MRI after GKRS (group 1), and 7 patients who experienced post- AO hemorrhage (group 2). We analyzed the enhancement persistence ratio (the percentage of AVMs with persisting enhancement on contrast-enhanced T1-weighted image after obliteration) and the change in size of the enhanced region over time in each patient.

RESULTS: The enhancement persistence ratio showed no significant difference between the 2 groups (89.4% vs 100% for groups 1 and 2, respectively; P = .401). While most cases in group 1 showed a tendency to decrease in size and gradually stabilize following GKRS, there were significantly more cases in group 2 with obvious increment of the enhanced regions within 1 year of angiographic obliteration compared with the previous measurement (4.96% vs 71.4% for groups 1 and 2, respectively; P < .0001).

CONCLUSION: Our results suggest that AVMs that show an increase in the size of the enhanced region within 1 year of angiographic obliteration should be followed up with caution for post-AO hemorrhage. Persisting enhancement itself is not positively associated with subsequent hemorrhage.

Exacerbation of Perihematomal Edema and Sterile Meningitis With Intraventricular Administration of Tissue Plasminogen Activator in Patients With Intracerebral Hemorrhage

Neurosurgery 66:631-638, 2010. DOI: 10.1227/01.NEU.0000367634.89384.4B

Intraventricular hemorrhage (IVH) is associated with a poor outcome. External ventricular drainage together with clot lysis through intrathecal tissue plasminogen activator (IT-tPA) has been proposed as a promising therapy. However, recent experimental work has implicated tissue plasminogen activator (tPA) in the pathogenesis of cerebral edema.

METHODS: We reviewed the records of all patients with IVH caused by primary supratentorial intracerebral hemorrhage who underwent external ventricular drainage without surgical evacuation between January 2001 and June 2008. Of these 30 patients, we identified 13 who received IT-tPA. The remaining 17 patients served as controls. Hemorrhage, edema volume, and IVH score were determined on admission and by follow-up computed tomographic scans for 96 hours after admission. Discharge outcome was evaluated using the modified Rankin Scale.

RESULTS: There were no significant differences between the treatment and controls in terms of age, Glasgow Coma Scale score, Graeb and LeRoux IVH scores, or intracerebral hemorrhage volume on admission. IT-tPA resulted in more rapid clearance of IVH as determined by the 96-hour decrease in both the Graeb IVH score (tPA, 3.00 ± .55; control, 1.00 ± 0.57; P = .05) and the LeRoux IVH score (tPA, 6.2 ± 0.80; control, 2.25 ± 1.32; P = .05). Patients treated with IT-tPA demonstrated significantly larger peak ratios of edema to intracerebral hemorrhage volume (1.24 ± 0.14 vs 0.70 ± 0.08 in controls; P = .002). Additionally, increased rates of sterile meningitis (46% vs 12%; P = .049) and a trend toward shunt dependence (38% vs 6%; P = .06) were observed in the tPA cohort. Nevertheless, no significant differences in outcome at discharge or length of hospital stay were observed between cohorts.

CONCLUSION: Although IT-tPA hastens the resolution of IVH, it may worsen perihematomal edema formation. Larger prospective studies are required to confirm these findings and to determine whether outcome is adversely affected by IT-tPA administration.