Multimodality treatment of nongalenic arteriovenous malformations in pediatric patients

Linear vein-based arteriovenous malformations in children

OBJECT

The authors reviewed the experience of a single surgeon in the surgical treatment of arteriovenous malformations (AVMs) in children, with specific attention to the angioarchitectural appearance of these lesions. Methods The authors performed a retrospective review of pediatric cases of AVM treated at a single institution over a 15-year period. Inclusion criteria consisted of pediatric age at time of treatment and resection of a pial AVM. The AVMs were considered linear-based if they had a single, centrally located, dominant vein with a linear configuration rather than the typical central nidus.

RESULTS

Sixty-seven patients, ranging in age from 6 months to 17 years, underwent surgical treatment of an AVM between January 1, 1990, and December 30, 2005. In these patients, 31 AVMs (46%) had a distinct linear configuration that was centered on a dominant draining vein ("vein-based"). These AVMs presented with hemorrhage (61%), incidental findings on imaging (16%), or seizures (13%). In 4 cases, AVM recurrence was noted on angiographic follow-up after postoperative angiography showed no residual lesion. Recurrence was seen at 1 year in 2 cases, and at 3 and 11 years in 1 case each.

CONCLUSIONS

A linear vein-based morphological pattern is common in pediatric AVMs and may recapitulate the embryological origins of the cerebral circulation. Surgical treatment in these cases can also be vein-based, through a narrow surgical corridor, which leads to minimal cortical disruption.

Radiosurgery of brain arteriovenous malformations in children

OBJECTIVE

The authors describe their experience in treating 22 children with a single brain arteriovenous malformation (bAVM) using a dedicated LINAC stereotactic radiosurgery unit.

METHODS

The findings of 22 consecutive patients < or = 18 years of age who underwent radiosurgery for a single bAVM and with at least 24 months of follow-up, or earlier proven obliteration,were reviewed. The median age at radiosurgery was 13.8 years,with a hemorrhagic presentation in 86%. Median bAVM-volume was 1.8 ml, with a median prescribed marginal dose of 19.0 Gy.

RESULTS

The crude complete obliteration-rate was 68% (n = 15) after a median follow-up of 24 months. The actuarial obliteration- rate was 45 % after two years and 64 % after three years. Patients with a radiosurgery-based AVM score < or = 1 more frequently had an excellent outcome than patients with a bAVM score > 1 (71% vs. 20%, P = 0.12), as well as an increased obliteration rate (P = 0.03) One patient died from a bAVM-related hemorrhage 27 months after radiosurgery, representing a postradiosurgery hemorrhage rate of 1.3%/year for the complete followup interval. Overall outcome was good to excellent in 68% (n = 15). Radiation-induced changes on MR imaging were seen in 36% (n = 8) after a median interval of 12.5 months, resulting in deterioration of pre-existing neurological symptoms in one patient.

CONCLUSIONS

Radiosurgery is a relatively effective, minimally invasive treatment for small bAVMs in children. The rebleeding rate is low, provided that known predilection places for bleeding had been endovascularly eliminated.Our overall results compare unfavourably to recent pediatric microsurgical series, although comparison between series remains imprecise. Nevertheless, when treatment is indicated in a child with a bAVM that is amenable to both microsurgery or radiosurgery, microsurgery should carefully be advocated over radiosurgery, because of its immediate risk reduction.

Gamma Knife surgery for intracranial arteriovenous malformations in children: a retrospective study in 103 patients

OBJECT

This retrospective study was designed to study the outcome in children with intracranial arteriovenous malformations (AVMs) treated with Gamma Knife surgery (GKS).

METHODS

One hundred and forty-two children were treated with GKS at the authors' institution between April 1997 and March 2006; of these, 103 patients with a mean follow-up of 26.4 months (range 6-96 months) were included. The mean age at presentation was 13.9 years (range 3-18 years). Eighty-six (83%) patients presented with hemorrhage. In 57 children the AVMs were Spetzler-Martin Grade I or II, and in 46 the AVMs were Grades III, IV, or V. The mean volume of the AVMs was 2.4 ml (range 0.04-23.3 ml). The mean marginal dose administered was 24.4 Gy (range 15-27 Gy). Follow-up angiography was advised at 2 years after GKS and yearly thereafter. In patients with residual AVMs, follow-up angiography was advised yearly until 4 years after GKS. If residual AVM was present, even on a follow-up angiogram obtained 4 years postsurgery, the GKS was considered a failure.

RESULTS

Complete obliteration of the AVM was documented in 34 (87%) of the 39 patients with complete angiographic follow-up. The 3- and 4-year actuarial rates of nidus obliteration were 66 and 86% respectively. Three patients (2.9%) experienced bleeding during the latency period, and symptomatic radiation-induced edema was noted in four patients (3.8%). A significantly higher incidence of radiation edema was noted in patients with AVM volumes greater than 3 ml and in patients with Spetzler-Martin Grade IV and V AVMs.

CONCLUSIONS

Gamma Knife radiosurgery is an effective modality for the treatment of intracranial AVMs in children, yielding high obliteration rates and low complication rates.

ROLE OF RADIOSURGERY IN THE MANAGEMENT OF CEREBRAL ARTERIOVENOUS MALFORMATIONS IN THE PEDIATRIC AGE GROUP

OBJECTIVE

To assess the safety and efficacy of radiosurgery for the management of arteriovenous malformations (AVMs) in the pediatric age group.

METHODS

We reviewed data from 100 children (44 girls and 56 boys) presenting a total of 103 AVMs treated by linear accelerator radiosurgery between December 1988 and May 2002. The median patient age was 12 years (range, 2–16 yr). Sixty-seven AVMs (65%) were in functional locations and 30% were inoperable. The mean AVM volume was 2.8 cm3 (range, 0.9–21.3 cm3). The mean marginal dose was 23 Gy (range, 15–25 Gy) and required between one and four isocenters. Fifty patients received multimodal treatments with embolization and/or surgery before and/or after radiosurgery. Given that 16 patients underwent two sessions of radiosurgery and one patient received three sessions, a total of 119 radiosurgical treatments were delivered. We maintained our clinical and angiographic follow-up for at least 36 months after irradiation or until the complete obliteration of the AVM was confirmed by angiography (our sole end point for judging clinical efficacy). Univariate and multivariate analysis were performed to determine predictive factors for obliteration.

RESULTS

Complete obliteration was achieved for 72 AVMs (70%). The permanent neurological deficit rate was 5%. One patient died because of rebleeding. None of our patients presented bleeding after an angiographically verified AVM obliteration. The main predictive factors for obliteration were low AVM volume and no previous embolization. Moreover, the younger the patient, the more effective the radiosurgery seemed to be.

CONCLUSION

Radiosurgery is a safe and effective treatment for AVMs in the pediatric age group. One criterion for success was the use of a prescription dose similar to that used with adult populations.

Pediatric arteriovenous malformation: University of Toronto experience using stereotactic radiosurgery

INTRODUCTION AND BACKGROUND

Arteriovenous malformations (AVMs) are congenital vascular lesions of the brain, which behave differently in pediatric population compared to adults. Treatment of pediatric AVMs includes a combination of microsurgery, embolization and radiation therapies. However, the role of radiosurgery in the treatment of pediatric AVMs is not fully accepted because of concerns regarding the long-term effects of radiation on the pediatric brain.

DISCUSSION

In this study, we review our experience at the University of Toronto with treating pediatric AVMs using linear accelerator-based (LINAC) radiosurgery over the past 15 years. We report our results, obliteration rates, and complications on a total of 40 patients. In addition, we provide a review of series published to date combined with our own results to determine whether radiosurgery is a safe and reasonable treatment modality for pediatric AVMs.

Pediatric arteriovenous malformations: a 15-year experience with an emphasis on residual and recurrent lesions

OBJECT

Pediatric arteriovenous malformations (AVMs) are generally treated with microsurgical resection to achieve complete obliteration. We review our experience treating AVMs in children, particularly those with residual or recurrent lesions.

METHODS

The records of 39 patients with AVMs (25 girls: 14 boys; average age 10.3 years) treated during a 15-year period were reviewed (mean follow-up 30 months). Three primary outcomes were analyzed: AVM obliteration by last follow-up, residual on postoperative angiograms and recurrence after angiographic "cure."

RESULTS

Most children (57%) presented with spontaneous intracerebral hemorrhage, the average nidus size was 3.4 cm, and the modal Spetzler-Martin grade was 2. AVMs were classified as compact (82%) or diffuse (18%). Most patients (90%) underwent surgery as their primary treatment. The immediate obliteration rate was 76% and the overall, long-term obliteration rate was 89%. Nine (23%) patients had residual nidus after initial treatment; five of these underwent further treatment that obliterated their lesion. Five (13%) patients developed recurrence within 6 years, including one patient with two recurrences. Three were successfully treated with a repeat resection. Patients with diffuse-type AVMs were at greater risk of having a persistent lesion (40%), residual lesion (44%), or recurrence (80%) at last follow-up.

CONCLUSION

Most pediatric AVMs can be successfully treated with microsurgical resection. Endovascular treatment is reserved primarily as a preoperative adjunct and stereotactic radiosurgery for inoperable AVMs. Patients may develop recurrences years after their original treatment. Patients with diffuse-type AVMs were less likely to be cured and more likely to have a residual or a recurrence.

Radiosurgery for epilepsy

Radiosurgery is an emerging therapeutic approach for the treatment of medically intractable epileptogenic foci. A favourable seizure outcome was first reported in studies of the effects of radiosurgery in the treatment of arteriovenous malformations and tumours. Radiosurgery has since been applied to the treatment of complex partial seizures with mesial-temporal-lobe onset. Nearly simultaneously, experimental evidence supporting the usefulness of radiosurgery to improve or abolish seizures has confirmed that stereotactic irradiation can preferentially affect epileptogenic versus normal cortex. Further work is clearly needed, but this technique might become an important approach in the management of mesial-temporal and extratemporal epilepsy, especially if refractory seizures arise from eloquent cortex or surgically challenging regions of brain.

Radiosurgery for arteriovenous malformations in children

OBJECT

The authors present the results of stereotactic radiosurgery performed in a consecutive series of children with arteriovenous malformations (AVMs) and analyze factors associated with successful radiosurgery for this condition.

METHODS

Between 1990 and 2001, 38 patients 18 years of age or younger underwent radiosurgery for AVMs. The median patient age was 15 years; 20 patients (53%) had experienced a prior hemorrhage. Twenty-seven AVMs (71%) were Spetzler-Martin Grade III or higher; 16 patients (42%) had AVMs located in the basal ganglia, thalamus, or brainstem. The median AVM volume was 3.4 cm3. The median radiosurgery-based AVM score was 1.08 according to the following formula: AVM score = 0.1 volume (cm3) + 0.02 x age (years) + 0.3 x location (frontal/temporal = 0; parietal/occipital/corpus callosum/cerebellar = 1; basal ganglia/thalamus/brainstem = 2). The median follow-up period was 42 months. One patient (3%) had an intraventricular hemorrhage 26 months after radiosurgery but experienced no new deficit. No patient had a permanent radiation-related complication after radiosurgery. Twenty-six patients (68%) had excellent outcomes (as defined by complete obliteration of the AVM with no new deficit) after radiosurgical treatment (21 cases determined using angiography and five using magnetic resonance imaging). Twelve patients (32%) remained unchanged (incomplete obliteration but no new deficit). Univariate analysis found that patient age, AVM volume, location, or Spetzler-Martin grade did not correlate with excellent outcomes. Patients whose radiosurgery-based AVM scores were 1 or lower experienced an excellent outcome more frequently than patients with an AVM score higher than 1 (88% compared with 52%, p = 0.03).

CONCLUSIONS

Radiosurgery was successful in the treatment of the majority of pediatric patients suffering from AVMs, and morbidity levels were minimal. The radiosurgery-based AVM grading scale accurately predicted these outcomes. Children whose AVMs are obliterated after radiosurgery should undergo repeated angiography after they reach adulthood to rule out the possibility of a recurrent nidus that would expose them to an ongoing risk of hemorrhage.

Preoperative endovascular brain mapping for intraoperative volumetric image guidance: preliminary concept and feasibility in animal models

Object

The authors describe a novel concept for brain mapping in which an endovascular approach is used, and they demonstrate its feasibility in animal models. The purpose of endovascular brain mapping is to delineate clearly the nonfunctional brain parenchyma when a craniotomy is performed for resection. The nonfunctional brain will be stained with sharp visual margins, differentiating it from the functional, nonstained brain. The authors list four essential criteria for developing an ideal endovascular mapping agent, and they describe seven potential approaches for accomplishing a successful endovascular brain map.

Methods

Four Sprague–Dawley rats and one New Zealand white rabbit were used to determine initial feasibility of the procedure. The animals were anesthetized, and the internal carotid artery was catheterized. Four potential brain mapping agents were infused into the right hemisphere of the five animals. Afterward, the brains were removed and each was analyzed both grossly and histologically.

Fluorescein and FD&C Green No. 3 provided good visual clarity and margins, but required blood–brain barrier (BBB) manipulation. Tantalum particles enabled avoidance of BBB manipulation, but provided inadequate visual clarity, probably because of their size. A Sudan black “cocktail” provided excellent clarity and margins despite remaining in the brain capillaries.

Conclusions

This is a novel application of the endovascular approach, and has broad potential for clinical neurosurgical brain mapping. The animal models in this study establish the feasibility of the procedure. However, further study is required to demonstrate safety, minimize toxicity, investigate stain durability, and improve the characteristics of potential mapping agents. The authors are planning to conduct future studies for identification of mapping agents that do not require BBB manipulation or vascular occlusion.

Complications of Cerebral Arteriovenous Malformation Embolization: Multivariate Analysis of Predictive Factors

OBJECTIVE:

Embolization is an important therapeutic modality in the multidisciplinary management of arteriovenous malformations (AVM); however, prior series have reported a wide variability in overall complication rates caused by embolization (10–50% neurological deficit, 1–4% mortality). In this study, we reviewed our experience with AVM embolization and analyzed factors that might predict complications and clinical outcomes after AVM embolization.

METHODS:

We analyzed our combined neurovascular unit's results with AVM embolization from 1993 to 2004 for the following outcomes measures: 1) clinically significant complications, 2) technical complications without clinical sequelae, 3) discharge Glasgow Outcome Scale score, and 4) death. To determine embolization efficacy, we analyzed perioperative blood transfusion and rate of AVM obliteration. Univariate and multivariate analyses were performed for patient age, sex, history of rupture, history of seizure, associated aneurysms, AVM size, deep venous drainage, eloquent location, Spetzler-Martin grade, number of embolization stages, number of pedicles embolized, and primary treatment modality.

RESULTS:

Over an 11 year period, 295 embolization procedures (761 pedicles embolized) were performed in 168 patients with embolization as the primary treatment modality (n = 16) or as an adjunct to surgery (n = 124) or radiosurgery (n = 28). There were a total of 27 complications in this series, of which 11 were clinically significant (6.5% of patients, 3.7% per procedure), and 16 were technical complications (9.5% of patients, 5.4% per procedure). Excellent or good outcomes (Glasgow Outcome Scale ≥ 4) were observed in 152 (90.5%) patients. Unfavorable outcomes (Glasgow Outcome Scale 1–3) as a direct result of embolization were both 3.0% at discharge and at follow-up, with a 1.2% embolization-related mortality. In the 124 surgical patients, 96.8% had complete AVM obliteration after initial resection, and 31% received perioperative transfusion (mean 1.4 units packed red blood cells per surgical patient). Predictors of unfavorable outcome caused by embolization by univariate analysis were deep venous drainage (P &lt; 0.05), Spetzler-Martin Grade III to V (P &lt; 0.05), and periprocedural hemorrhage (P &lt; 0.0001) and by multivariate analysis were Spetzler-Martin III to V (odds ratio 10.6, P = 0.03) and periprocedural hemorrhage (odds ratio 17, P = 0.004).

CONCLUSION:

In a single-center, retrospective, nonrandomized study, 90.5% of patients had excellent or good outcomes after AVM embolization, with a complication rate lower than previously reported. Spetzler-Martin grade III to V and periprocedural hemorrhage were the most important predictive factors in determining outcome after embolization.

Gamma Knife radiosurgery for cerebral arteriovenous malformations in children/adolescents and adults. Part II: Differences in obliteration rates, treatment-obliteration intervals, and prognostic factors

PURPOSE

To evaluate and compare obliteration rates (OBRs) and treatment-obliteration intervals (TOIs) for cerebral arteriovenous malformations (cAVMs) treated with Gamma Knife radiosurgery in children/adolescents and adults; and to determine factors predicting the OBR and TOI in these two populations.

METHODS AND MATERIALS

This study concerned 62 children/adolescents and 193 adults observed for > or = 3 years. Fisher exact two-tailed and Wilcoxon rank-sum tests, multiple logistics, and Cox proportional hazard models were used for statistical analysis.

RESULTS

The overall OBR was 85.5% in children/adolescents and 87.6% in adults (p = 0.671), but children/adolescents showed higher 36-month actuarial OBRs (69.35%) and shorter median TOIs (25.7 months) than adults (66.84% and 28.2 months; p = 0.006 and p = 0.017, respectively). In children/adolescents, lower Spetzler-Martin grades (p = 0.043) and younger age (p = 0.019) correlated significantly with OBRs, and lower Spetzler-Martin grades (p = 0.024) and noneloquent cAVM locations (p = 0.046) with TOIs. In adults, low flow through the cAVM and < 6.2-cm3 volume were associated with both OBR and TOI (p = 0.012 and p = 0.002, respectively).

CONCLUSIONS

The differences in OBRs within 3 years and TOIs, although slight, seem to show that pediatric cAVMs behave differently from those in adults after Gamma Knife radiosurgery.

Gamma knife radiosurgery for cerebral arteriovenous malformations in children/adolescents and adults. Part I: Differences in epidemiologic, morphologic, and clinical characteristics, permanent complications, and bleeding in the latency period

PURPOSE

To compare the epidemiologic, morphologic, and clinical characteristics of 92 children/adolescents (Group A) and 362 adults (Group B) with cerebral arteriovenous malformations (cAVMs) considered suitable for radiosurgery; to correlate radiosurgery-related permanent complication and post-radiosurgery bleeding rates in the 75 children/adolescents and 297 adults available for follow-up.

METHODS AND MATERIALS

Radiosurgery was performed with a model C 201-source Co60 Leksell Gamma Unit (Elekta Instruments, Stockholm, Sweden). Fisher exact two-tailed, Wilcoxon rank-sum, and two-sample binomial exact tests were used for statistical analysis.

RESULTS

There were significant differences between the two populations in sex (p = 0.015), clinical presentation (p = 0.001), and location (p = 0.008). The permanent complication rate was lower in younger (1.3%) than in older patients (5.4%), although the difference was not significant (p = 0.213). The postradiosurgery bleeding rate was lower in Group A (1.3%) than in Group B (2.7%) (p = 0.694), with global actuarial bleeding rates of 0.56% per year and 1.15% per year, respectively.

CONCLUSIONS

The different characteristics of child/adolescent and adult cAVMs suggest that they should be considered two distinct vascular disorders. The similar rates of radiosurgery-related complications and latency period bleeding in the two populations show that gamma knife radiosurgery does not expose young patients to a higher risk of sequelae than that for older patients.

Intensity-modulated radiosurgery for childhood arteriovenous malformations

PURPOSE

Presentation of intensity-modulated radiosurgery (IMRS) for the treatment of inoperable, complex shaped pediatric arterio-venous malformations AVM.

METHOD

Between 03/99 and 11/04, IMRS was delivered to seven children aged six to 18 years. Prescribed minimum doses ranged from 17.5 to 20 Gy (median 18 Gy). Radiosurgery planning and delivery used a serial tomotherapeutic IMRT technique (Peacock IMRT, North American Scientific/Nomos, Cranberry Township, PA) over two to four couch angles. A linear accelerator attached binary multi-leaf collimator was used to generate pencil beams of 10 mm by either 8.5 or 4.0 mm. Treatment planning employed an inverse treatment planning optimization algorithm. Parameters submitted to the treatment planning system were: prescription dose (PD), volume of target allowed to receive less dose (standard 3%), minimum dose (0.5 Gy less than PD), and maximum dose (200% of PD). Planning system specific IMRS target and tissue types were selected to prioritize dose conformality over dose homogeneity. The prescription isodose encompassed at least 95% of the target volume. We calculated conformality (CI) and homogeneity indices (HI) to characterize the quality of IMRS plans, and summarized preliminary clinical outcomes.

FINDINGS

Target volumes ranged from 0.71 to 63.02 cm(3) (median 13.8 cm(3), 6/7 AVM larger than 10 cm(3)). Median CI was 1.07 (range 1.05 to 1.7) according to RTOG criteria. Median HI was 1.12 (range 1.09 to 1.23). During limited follow-up (median 32 months, range 5 to 53 months), two AVM completely obliterated at 19 and 22 months, and partial obliteration (>75%) was observed in three cases. No treatment-related side effects, other than acute nausea and temporary headaches interpreted as being associated with changes in cerebral blood distribution, were observed.

CONCLUSIONS

IMRS can allow for highly conformal planning and delivery of radiosurgery radiation doses even if pediatric AVM target volumes are large and/or highly complex in shape. This technique has been seen to result in favorable preliminary outcomes, thus supporting future exploration of this technique in pediatric and adult patients.

Endovascular Treatment of Cerebral Arteriovenous Malformations

The modern management of cerebral arteriovenous malformations (AVMs) is based on three therapeutic modalities: microneurosurgery, endovascular embolization, and stereotactic radiosurgery. Embolization facilitates subsequent radiosurgery by reducing the volume of the nidus, prepares the resection of surgically accessible AVMs, and immediately addresses the risks related to associated intra/extranidal aneurysms and arteriovenous fistulas. We discuss in this article the current state of AVM endovascular therapy.

Leksell gamma knife radiosurgery for cerebral arteriovenous malformations in pediatric patients

OBJECTS

The authors report their experience of gamma knife radiosurgery (GKR) in a large series of pediatric cerebral arteriovenous malformations (cAVMs). The advantages, risks and failures of this approach are presented and discussed.

METHODS

Gamma knife radiosurgery was performed on 63 children aged < or =16 years. Haemorrhage was the clinical onset in 50 out of 63 cases. The mean pre-GK cAVM volume was 3.8 cm(3). Fifty-eight out of 63 cAVMs were Spetzler-Martin grades I-III. Most lesions (47 out of 63) were in eloquent or deep-seated brain regions.

CONCLUSION

Gamma knife radiosurgery-related complications occurred in 2 out of 47 cases with an available follow-up (1 had transient and 1 permanent morbidity). No bleeding occurred during the latency period. In 39 children with >36-month follow-up, complete cAVM occlusion was angiographically documented in 31, with a 3- and 4-year actuarial obliteration rate of 72 and 77% respectively. High rates of complete obliteration and very low frequency of permanent morbidity with no bleeding during the latency period encourage widespread application of GKR in the treatment of pediatric cAVMs.

Effect of Presenting Hemorrhage on Outcome after Microsurgical Resection of Brain Arteriovenous Malformations

OBJECTIVE:

We hypothesized that patients with unruptured arteriovenous malformations (AVMs) at presentation have an increased risk of deterioration compared with patients with ruptured AVMs.

METHODS:

A consecutive series of 224 patients treated microsurgically by a single neurosurgeon during a period of 6.4 years was analyzed. Initial hemorrhagic presentation was the primary predictor variable. Neurological outcomes were assessed by use of the Modified Rankin Scale (MRS) and Glasgow Outcome Scale (GOS), and logistic regression identified predictors of deterioration at follow-up (mean duration, 1.3 yr) relative to baseline before any intervention.

RESULTS:

Overall, 120 patients (54%) presented with hemorrhage, and all 224 patients underwent microsurgical resection. Complete resection was achieved in 220 patients (98%). According to GOS score, 13 patients (5.8%) deteriorated; according to MRS score, 45 patients (20.1%) deteriorated. Fifteen patients (6.7%) died. Hemorrhagic presentation was associated with improved outcomes, with a mean change in MRS score of +0.89 in patients with ruptured AVMs and −0.38 in patients with unruptured AVMs (P &lt; 0.001). The final mean MRS scores in patients with unruptured AVMs were better than those in patients with ruptured AVMs (1.44 versus 1.90; P = 0.048). Presentation with an unruptured AVM was a predictor of worsening MRS score (odds ratio, 2.33; 95% confidence interval, 1.3–4.3; P = 0.006) but not of worsening GOS score.

CONCLUSION:

Presentation with AVM hemorrhage is an underappreciated predictor of outcome after therapy that includes microsurgical resection. Patients with ruptured AVMs tended to have deficits at presentation and generally improved after surgery, whereas patients with unruptured AVMs tended to have normal or nearly normal neurological function at presentation and were susceptible to worsening, albeit slight, as measured by MRS scores. Sensitive outcome measures such as MRS detect subtle symptoms and impairments missed by coarser measures such as GOS. Patients should be counseled that the risks associated with elective resection of unruptured AVMs may be higher than recognized previously. Hemorrhagic brain injury and its secondary effects may mask this surgical morbidity.

Surgical results in pediatric Spetzler-Martin grades I-III intracranial arteriovenous malformations

OBJECTS

The goal of cerebral arteriovenous malformation (AVM) therapy in pediatric patients should be complete resection or obliteration of the AVM to eliminate subsequent hemorrhage, because of high mortality and morbidity rates related to hemorrhage in addition to the longer life expectation. Despite advances in Gamma knife radiosurgery and in endovascular embolization, surgical resection is still the gold standard for treating cerebral AVMs.

METHODS

Between 1986 and 2003, 20 children were surgically treated for cerebral AVMs. The AVMs were graded I, II, and III using the Spetzler-Martin (S-M) Grading Scale. Good recovery was achieved in 18 out of 20 patients (90%) and only 1 patient was moderately disabled (5%). There was one mortality (5%) related to the preoperative deep comatose state of the patient. The total obliteration rate was 89% (17 out of 19).

CONCLUSION

For S-M grade I-III AVMs, surgical resection is the treatment of choice, considering its high cure rate and low morbidity and mortality rates.

Combined endovascular and microsurgical management of giant and complex unruptured aneurysms

Object

The purpose of this study was to assess the efficacy and describe the technical features of combined endovascular and microsurgical treatments for complex and giant unruptured intracranial aneurysms.

Methods

A prospectively maintained database was reviewed to identify all patients with unruptured intracranial aneurysms who were treated with combined techniques. Twenty-one lesions were treated in as many patients: six lesions involved the posterior cerebral artery (PCA); seven the cavernous portion of the internal carotid artery (ICA); two the basilar apex; two the basilar trunk; and one each the anterior communicating artery, anterior cerebral artery, petrous ICA, and cervical ICA. Aneurysms were treated with combined extracranial–intracranial bypass procedures and parent-vessel occlusion, flow redirection, or arterial transposition.

Aneurysm occlusion was achieved in 20 patients. In the remaining patient the aneurysm recurred, requiring stent-assisted repeated coil placement. Three patients suffered permanent neurological deficits related to treatment, and three died, two of whom had basilar trunk aneurysms.

Conclusions

Certain complex aneurysms may be treated optimally by combining endovascular and surgical procedures. A low incidence of complications follows treatment of anterior circulation aneurysms. Treatment of complex posterior circulation aneurysms is associated with a higher incidence of complications, although this likely reflects the more complex nature of these lesions. The risks of this combined treatment strategy are likely lower than the risks associated with the natural history of this subset of aneurysms.

Scalp arteriovenous malformation draining into the superior sagittal sinus associated with an intracranial arteriovenous malformation: just a coincidence? Case report

OBJECTIVE AND IMPORTANCE

Recent experimental and clinical evidence suggests that hemodynamic changes in the venous system can induce the formation of new arteriovenous malformations (AVMs). In a rat model, increased venous pressure induces the formation of soft tissue and dural AVMs. We report a clinical observation that may support these data.

CLINICAL PRESENTATION

A 4-year-old boy with a midline scalp AVM draining into the superior sagittal sinus had an associated intracranial/parenchymal AVM. The cerebral AVM increased venous pressure in the superior sagittal sinus as revealed by angiography.

INTERVENTION

The scalp AVM was resected, and the intracranial AVM was treated by use of the gamma knife.

CONCLUSION

On the basis of reported experimental data and the morphological and hemodynamic characteristics in this patient's two lesions, we suggest that the scalp AVM might have been induced by hypertension in the superior sagittal sinus. This clinical observation supports the notion suggested by experimental studies that hemodynamic changes can induce the formation of associated AVMs.

Survival of infants diagnosed with encephalocele in Atlanta, 1979-98

This study aimed to evaluate the survival of a cohort of liveborn infants diagnosed with encephalocele during a 20-year period and the variation of such survival by selected demographic and clinical characteristics. We reviewed data from the Metropolitan Atlanta Congenital Defects Program (MACDP) to ascertain all live births diagnosed with encephalocele (n = 83) from 1979 to 1998. Of these, 66 (79%) had isolated defects. Among 70 liveborn infants with site of the defect specified, 50 were classified as having posterior and 20 with anterior defects. To identify their vital status, we used data from MACDP hospital records and vital records from the State of Georgia supplemented by linking registry data with the National Death Index from 1979 to 1999. Among children with encephalocele, 76.0% of the deaths (19/25) occurred during the first day of life. The survival probability to 1 year of age was 70.8%[95% confidence intervals (CI) 60.9, 80.7] and to 20 years of age was 67.3%[95% CI 55.7, 78.8]. In multivariable analysis, factors associated with increased mortality were low birthweight (<2500 g) [relative risk (RR) 5.18; 95% CI 2.13, 12.63], presence of multiple defects (RR 2.82; 95% CI 1.19, 6.69) and black race (RR 2.36; 95% CI 0.95, 5.85). Overall survival for infants with multiple defects (41.2%) was significantly poorer than survival among those with isolated defects (74.3%). A 70% decrease in risk of mortality was observed among infants born with encephalocele during 1989-98 compared with those born during 1979-88, but this decrease was evident only among cases with low birthweight (RR 0.29; 95% CI 0.01, 0.90). This study highlights the prognostic importance of multiple defects and low birthweight for infants with encephalocele and identifies a statistically significant difference in survival by race. This information is useful for clinicians and families who must plan for the long-term care of affected children.

Arteriovenous Malformations in the Brain

Arteriovenous malformations (AVM) are a leading cause of intracerebral hemorrhage, especially among the young. Because they pose a lifelong risk of serious bleeding, definitive treatment to obliterate the AVM should be pursued in the majority of patients. Microsurgical resection of a small AVM located in the superficial or non- eloquent brain achieves high cure rates with low morbidity, and is the recommended choice for such lesions. Radiosurgery with gamma knife, linear accelerator, or heavy ion beam irradiation is an alternative therapy for AVM treatments less than 3 centimeters in diameter located in brain regions where surgery is likely to produce major neurologic deficits, or for patients unable or unwilling to undergo craniotomy and resection. Cure rates are lower than with microsurgery, and obliteration of the lesion may take 2 to 3 years, during which time the patient remains at risk for hemorrhage. Because rates of recurrent hemorrhage are higher than rates of initial bleeding, radiosurgery may be a good option for patients who have not yet had an intracranial hemorrhage. Endovascular embolization as sole therapy is curative only in a small percentage of cases, but is recommended as part of a multimodal approach to reduce the size of a large AVM, and decrease bleeding risk of lesions with multiple or inaccessible feeding vessels or associated aneurysms prior to surgery or radiotherapy. Currently, treatment decisions must rely solely on Class III evidence from case series and expert opinion. Randomized clinical trials are needed to provide objective guidelines for the future management of patients with an AVM.

Surgical approaches to vascular anomalies of the child's brain

The population of pediatric patients with cerebrovascular disease presents a unique set of challenges to the neurosurgeon. The wide scope of pathology, including arteriovenous malformations, cavernous malformations and moyamoya disease, coupled with marked advances in diagnosis and treatment of these conditions over the past several years has resulted in a proliferation of the literature related to this subject. The present review provides an overview of current methods of surgical treatment for pediatric cerebrovascular diseases, focusing on indications and use of recent refinements of pre-existing surgical approaches, and newly evolved operative techniques developed to treat these entities.

Arteriovenous malformations

Arteriovenous malformations of the brain are congenital vascular lesions that affect 0.01-0.50% of the population, and are generally present in patients aged 20-40 years. The usual clinical presentations are haemorrhage, seizures, progressive neurological deficit, or headache. Results of natural history studies have shown a yearly haemorrhage rate of 1-4%. Frequency of rebleeding has increased over the years, and several factors that increase risk of haemorrhage have been identified. Although substantial, the morbidity associated with haemorrhages could be less than previously thought. Over the past decade, great advances have been made in application of endovascular embolisation techniques, stereotactic radiosurgery, and microsurgery, allowing effective multidisciplinary treatment of arteriovenous malformations, including those previously deemed to be untreatable. Increasing attention has been paid to management of flow-related aneurysms associated with these malformations. Finally, many reports of recurrent arteriovenous malformations have coincided with new theories regarding the embryogenesis of these disorders and laboratory work suggesting their proliferative potential.