Neurosurgery Blog

Neurosurgery 72:922–929, 2013

Dural splitting decompression may be an effective and safe treatment for Chiari I malformation.

OBJECTIVE: To compare clinical outcomes, complications, and resource utilization for patients undergoing Chiari I decompression with or without duraplasty.

METHODS: Between 2000 and 2009, the senior author performed 113 Chiari I decompression operations with dural splitting or duraplasty in children less than 18 years of age; 110 were included in a retrospective cohort analysis of safety, efficacy, and treatment cost. Patients without significant syringomyelia underwent dural splitting decompression, and patients with syringomyelia underwent duraplasty.

RESULTS: Sixty-three patients without significant syringomyelia (57%) underwent dural splitting decompression. They were significantly younger than patients undergoing duraplasty (8.3 ± 4.9 years vs 10.4 ± 4.4 years; P < .05). Headaches improved or resolved in most patients in both groups (90.5% vs 93.6%; P = .59). Dysphagia, long tract signs, cranial nerve, and bulbar symptoms also improved similarly in both groups. Three duraplasty patients were treated medically for aseptic meningitis; one underwent reoperation for a symptomatic pseudomeningocele. No patient undergoing dural splitting decompression experienced a cerebrospinal fluid-related complication. Extradural decompression required less operative time than duraplasty (105.5 vs 168.9 minutes, P < .001), a shorter length of stay (2.4 vs 2.8 days, P = .011), and lower total cost for the primary hospitalization ($26 837 vs $29 862, P = .015).

CONCLUSION: In this retrospective cohort study, dural splitting decompression was equally effective, safer, and lower cost for treatment of Chiari I malformation without syringomyelia. A multicenter trial with groups balanced for the presence of syringomyelia is necessary to determine whether these results are generalizable.

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.

SPINE Volume 38, Number 6, pp E344–E349

Diastematomyelia is a rare entity, which presents distinct clinical characteristics and requires different managements compared with other more common occult spinal dysraphism.

Methods. A total of 156 patients with diastematomyelia were reviewed. All the patients underwent neurological and radiological examinations. Surgical excision of the lesion was performed for most patients and intradural exploration of the lumbar region was done to release tethering of conus in some patients. One patient died and autopsy was performed. Follow-up was carried out for all the patients, including surgical and nonsurgical approaches.

Results. There were 123 cases of type I diastematomyelia and 33 cases of type II diastematomyelia. The lumbar and thoracolumbar region was the most common site for diastematomyelia, and most spinal cords were split among 6 segments. The postoperative course was complicated by cerebrospinal fl uid leakage in 2 patients, temporary neurological deterioration in 4 patients, and epidural hematoma in 1 patient. All cases did not have aggravation of symptoms during the follow-up of 2 to 20 years (mean of 4.5 yr). For the 123 patients with type I diastematomyelia, clinical symptoms were improved in 96 after surgical intervention and no worsening or occurrence of new clinical signs were observed during the follow-up. Those who did not receive surgery showed stabilization of neurological manifestation. Of the 33 type II cases, 9 surgical patients remained neurologically stable during the postoperative years without signifi cant improvement in function, and 24 nonsurgical patients neither improved nor worsened in their neural defi cit.

Conclusion. Surgical treatment is the necessary management for type I diastematomyelia causing progressive neurological deterioration or with tethered fi lum, whereas conservative treatment is recommended to asymptomatic type I diastematomyelia and all type II diastematomyelia.

J Neurosurg 117:942–946, 2012

Chiari malformation Type I (CM-I) is characterized by hindbrain deformity. We investigated the effects of craniocervical decompression surgery on the anatomical features of hindbrain deformity with a prospective MRI study of patients with CM-I.

Methods. A prospective longitudinal study was conducted in 48 patients with CM-I (39 with syringomyelia) treated with craniocervical decompression. Clinical examinations and cervical MRI were performed before surgery and 1 week, 3–6 months, and annually after surgery. Hindbrain deformity was defined by tonsillar ectopia, pointed cerebellar tonsils, and/or cervicomedullary protuberance. The length of the clivus, basiocciput (sphenooccipital synchondrosis to basion), supraocciput (internal occipital protuberance to opisthion), and anteroposterior (AP) width of CSF pathways at the foramen magnum were measured and compared with those from 18 healthy volunteers (control group).

Results. Before surgery, the patients’ posterior fossa bones were short and their CSF pathways were narrow. All patients had tonsillar ectopia (mean [± SD] 12.3 ± 5.1 mm; normal 0.3 ± 1.0). The majority of patients had pointed tonsils and more than two-thirds exhibited a cervicomedullary protuberance. Clivus and basiocciput lengths were significantly shorter than the values obtained in the control group. However, the supraocciput length did not differ significantly from control measurements. The mean bulbopontine sulcus distance superior to the basion was 9.5 ± 2.6 mm (vs 13.6 ± 2.8 mm in controls; p < 0.0001). The AP widths of the CSF pathways at the level of the foramen magnum were significantly narrowed. After surgery, CSF pathways significantly expanded both ventrally and dorsally. By 3–6 months after surgery, pointed tonsils became round, cervicomedullary protuberance disappeared, and tonsillar ectopia diminished by 51% (to 6.0 ± 3.3 mm; p < 0.0001).

Conclusions. The cerebellar tonsils and brainstem assumed a normal appearance within 6 months after craniocervical decompression. These findings support the concept that the CM-I is not a congenital malformation of the neural elements but rather an acquired malformation that arises from pulsatile impaction of the cerebellar tonsils into the foramen magnum.

Neurosurgery 71:365–380, 2012 DOI: 10.1227/NEU.0b013e31825c3426

Foramen magnum decompression is widely accepted as the treatment of choice for Chiari I malformation. However, important surgical details of the procedure are controversial.

OBJECTIVE: This study analyzes 371 decompressions focusing on intraoperative findings, analysis of complications, and long-term outcomes.

METHODS: Among 644 patients between 1985 and 2010, 359 patients underwent 371 decompressions. Surgery for symptomatic patients consisted of suboccipital craniectomy, C1 laminectomy, arachnoid dissection, and duraplasty. Short-term results were determined after 3 months; long-term outcomes were evaluated with Kaplan-Meier statistics.

RESULTS: The mean age was 40 ± 16 years; mean follow-up was 49 ± 56 months; 75.8% demonstrated syringomyelia. The complication rate was 21.8% with permanent surgical morbidity of 3.2% and surgical mortality of 1.3%. Of the patients, 73.6% reported improvement after 3 months; 21% were unchanged. Overall, 14.3% demonstrated a neurological deterioration within 5 years and 15.4% within 10 years. The severity of neurological symptoms correlated with the grade of arachnoid pathology. Outcome data correlated with the number of previous decompressions, severity of arachnoid pathology, handling of the arachnoid, type of duraplasty, and surgical experience. Firsttime decompressions with arachnoid dissection and an alloplastic duraplasty resulted in surgical morbidity for 2.0%, a 0.9% mortality rate, postoperative improvement after 3 months for 82%, and neurological recurrence rates of 7% after 5 years and 8.7% after 10 years.

CONCLUSION: Arachnoid pathology in Chiari I malformation has an impact on clinical symptoms and postoperative results. Decompressions with arachnoid dissection and an alloplastic duraplasty performed by surgeons experienced with this pathology offer a favorable long-term prognosis.

J Neurosurg Spine 16:107–113, 2012. DOI: 10.3171/2011.10.SPINE11199

The primary goal of this study was to review the immediate postoperative neurological function in patients surgically treated for symptomatic cervical spine disease without intraoperative neurophysiological monitoring. The secondary goal was to assess the economic impact of intraoperative monitoring (IOM) in this patient population.

Methods. This study is a retrospective review of 720 consecutively treated patients who underwent cervical spine procedures. The patients were identified and the data were collected by individuals who were not involved in their care.

Results. A total of 1534 cervical spine levels were treated in 720 patients using anterior, posterior, and combined (360°) approaches. Myelopathy was present preoperatively in 308 patients. There were 185 patients with increased signal intensity within the spinal cord on preoperative T2-weighted MR images, of whom 43 patients had no clinical evidence of myelopathy. Three patients (0.4%) exhibited a new neurological deficit postoperatively. Of these patients, 1 had a preoperative diagnosis of radiculopathy, while the other 2 were treated for myelopathy. The new postoperative deficits completely resolved in all 3 patients and did not require additional treatment. The Current Procedural Terminology (CPT) codes for IOM during cervical decompression include 95925 and 95926 for somatosensory evoked potential monitoring of the upper and lower extremities, respectively, as well as 95928 and 95929 for motor evoked potential monitoring of the upper and lower extremities. In addition to the charge for the baseline [monitoring] study, patients are charged hourly for ongoing electrophysiology testing and monitoring using the CPT code 95920. Based on these codes and assuming an average of 4 hours of monitoring time per surgical case, the savings realized in this group of patients was estimated to be $1,024,754.

Conclusions. With the continuing increase in health care costs, it is our responsibility as providers to minimize expenses when possible. This should be accomplished without compromising the quality of care to patients. This study demonstrates that decompression and reconstruction for symptomatic cervical spine disease without IOM may reduce the cost of treatment without adversely impacting patient safety.

J Neurosurg 115:1106–1114, 2011. DOI: 10.3171/2011.6.JNS11506

We reviewed our experience with pineal cysts to define the natural history and clinical relevance of this common intracranial finding.

Methods. The study population consisted of 48,417 consecutive patients who underwent brain MR imaging at a single institution over a 12-year interval and who were over 18 years of age at the time of imaging. Patient characteristics, including demographic data and other intracranial diagnoses, were collected from cases involving patients with a pineal cyst. We then identified all patients with pineal cysts who had been clinically evaluated at our institution and who had at least 6 months of clinical and imaging follow-up. All inclusion criteria for the natural history analysis were met in 151 patients.

Results. Pineal cysts measuring 5 mm or larger in greatest dimension were found in 478 patients (1.0%). Of these, 162 patients were male and 316 were female. On follow-up MR imaging of 151 patients with pineal cyst at a mean interval of 3.4 years from the initial study, 124 pineal cysts remained stable, 4 increased in size, and 23 decreased in size. Cysts that were larger at the time of initial diagnosis were more likely to decrease in size over the follow-up interval (p = 0.004). Patient sex, patient age at diagnosis, and the presence of septations within the cyst were not significantly associated with cyst change on follow-up.

Conclusions. Follow-up imaging and neurosurgical evaluation are not mandatory for adults with asymptomatic pineal cysts.

Neurosurgery 69[ONS Suppl 2]:ons176–ons183, 2011 DOI: 10.1227/NEU.0b013e318219563c

Surgical approaches to colloid cysts of the third ventricle have evolved over time. In recent years, endoscopy has been recognized as an effective alternative to open surgery. The disadvantage of endoscopic treatment is the difficulty in controlling the adhesion of the cyst to the roof of the third ventricle and in obtaining complete removal of the cyst.

OBJECTIVE: To design and carry out a supraorbital approach to obtain a better viewing angle of the cyst and better control of the adhesion of the cyst to the roof of the third ventricle.

METHODS: From September 2005 to February 2008, we operated on 7 consecutive patients with colloid cysts in the third ventricle. All procedures were performed with the endoscopic supraorbital approach. The endoscopic procedure was performed with a rigid STORZ endoscope with 3 working channels. In 4 patients, the surgical supraorbital trajectory was planned with the help of a navigator.

RESULTS: The procedures lasted between 60 and 110 minutes, including the registration on the navigation system. Near-total removal of the cyst was achieved in 6 patients. All patients were discharged within 6 days.

CONCLUSION: Endoscopic treatment may be an effective and safe alternative to open surgical craniotomy. Our series shows that the endoscopic supraorbital endoscopic resection is a valuable approach to colloid cysts of the third ventricle.

J Neurosurg 115:647–658, 2011.DOI: 10.3171/2010.11.JNS102148

The aim of this paper was to measure the posterior fossa (PF) volume increase resulting from a givensized occipital craniectomy in Chiari malformation Type I surgery and to analyze its correlations with the PF size and the treatment response, with the perspective of tailoring the amount of bone removal to the patient-specific PF dimensions.

Methods. Between January 2005 and June 2006, 11 adult patients with symptomatic Chiari malformation Type I underwent a standardized PF decompression. A prospective evaluation with clinical examination, functional grading, and MR imaging measurement protocols was performed pre- and postoperatively. A method is reported for the measurement of PF volume (PFV) after surgery. The degree of PFV increase was compared with the preoperative size of the PF and with the clinical outcome.

Results. All 11 patients improved postoperatively, with complete and partial recovery in 4 and 7 patients, respectively. No postoperative complication occurred after a mean follow-up period of 45 months. The mean relative increase in PFV accounted for 10% (range 1.5%–19.7%) of the initial PFV; the increase was greater in cases in which the PF was small (r = -0.52, p = 0.09) and the basiocciput was short (r = -0.37, p = 0.2). A statistically significant positive correlation was found between the degree of PFV increase and the treatment response (p = 0.014); complete recovery was observed with a PFV increase of 15% and partial recovery with an increase of 7%.

Conclusions. The treatment response is significantly influenced by the degree of PFV increase, which is dependent on the size of the PF and the extent of the craniectomy, suggesting that the optimal patient-specific PFV increase could be predicted on the basis of preoperative MR imaging and enhancing the perspective that the craniectomy size could be tailored to the individual PFV.

Neurosurg Focus 31 (3):E4, 2011. DOI: 10.3171/2011.6.FOCUS11106

Resolution of syringomyelia is common following hindbrain decompression for Chiari malformation, yet little is known about the kinetics governing this process. The authors sought to establish the volumetric rate of syringomyelia resolution.

Methods. A retrospective cohort of patients undergoing hindbrain decompression for a Chiari malformation Type I with preoperative cervical or thoracic syringomyelia was identified. Patients were included in the study if they had at least 3 neuroimaging studies that detailed the entirety of their preoperative syringomyelia over a minimum of 6 months postoperatively. The authors reconstructed the MR images in 3 dimensions and calculated the volume of the syringomyelia. They plotted the syringomyelia volume over time and constructed regression models using the method of least squares. The Akaike information criterion and Bayesian information criterion were used to calculate the relative goodness of fit. The coefficients of determination R² (unadjusted and adjusted) were calculated to describe the proportion of variability in each individual data set accounted for by the statistical model.

Results. Two patients were identified as meeting inclusion criteria. Plots of the least-squares best fit were identified as 4.01459e-^0.0180804x and 13.2556e^-0.00615859x. Decay of the syringomyelia followed an exponential model in both patients (R² = 0.989582 and 0.948864).

Conclusions. Three-dimensional analysis of syringomyelia resolution over time enables the kinetics to be estimated. This technique is yet to be validated in a large cohort. Because syringomyelia is the final common pathway for a number of different pathological processes, it is possible that this exponential only applies to syringomyelia related to treatment of Chiari malformation Type I.

J Neurosurg Pediatrics 8:214–221, 2011.  DOI: 10.3171/2011.5.PEDS1122

The natural history of the Chiari malformation Type I (CM-I) is incompletely understood. The authors report on the outcome of a large group of patients with CM-I that were initially selected for nonsurgical management.

Methods. The authors identified 147 patients in whom CM-I was diagnosed on MR imaging, who were not offered surgery at the time of diagnosis, and in whom at least 1 year of clinical and MR imaging follow-up was available after the initial CM-I diagnosis. These patients were included in an outcome analysis.

Results. Patients were followed clinically and by MR imaging for a mean duration of 4.6 and 3.8 years, respectively. Of the 147 patients, 9 had new symptoms attributed to the CM-I during the follow-up interval. During this time, development of a spinal cord syrinx occurred in 8 patients; 5 of these patients had a prior diagnosis of a presyrinx state or a dilated central canal. Spontaneous resolution of a syrinx occurred in 3 patients. Multiple CSF flow studies were obtained in 74 patients. Of these patients, 23 had improvement in CSF flow, 39 had no change, and 12 showed worsening CSF flow at the foramen magnum. There was no significant change in the mean amount of cerebellar tonsillar herniation over the follow-up period. Fourteen patients underwent surgical treatment for CM-I. There were no differences in initial cerebellar tonsillar herniation or CSF flow at the foramen magnum in those who ultimately underwent surgery compared with those who did not.

Conclusions. In patients with CM-Is that are selected for nonsurgical management, the natural history is usually benign, although spontaneous improvement and worsening are occasionally seen.

J Neurosurg Pediatrics 8:177–183, 2011. DOI: 10.3171/2011.5.PEDS10362

Posterior fossa decompression with duraplasty for Chiari malformation Type I (CM-I) is a common pediatric neurosurgery procedure. Published series report a complication rate ranging from 3% to 40% for this procedure. Historically, many dural substitutes have been used, including bovine grafts, human cadaveric pericardium, synthetic dura, and autologous pericranium. The authors hypothesized that a recently observed increase in complications was dependent on the graft used.

Methods. Between January 2004 and January 2008, 114 consecutive patients ≤ 18 years old underwent primary CM-I decompression using duraplasty. Records were retrospectively reviewed for short- and intermediate-term complications and operative technique, focusing on the choice of duraplasty graft with or without application of a tissue sealant.

Results. The average age of the patients was 8.6 years. The dural graft used was variable: 15 were treated with cadaveric pericardium, 12 with Durepair, and 87 with EnDura. Tisseel was used in 75 patients, DuraSeal in 12, and no tissue sealant was used in 27 patients. The overall complication rate was 21.1%. The most common complications included aseptic meningitis, symptomatic pseudomeningocele, or a CSF leak requiring reoperation. The overall complication rates were as follows: cadaveric pericardium 26.7%, Durepair 41.7%, and EnDura 17.2%; reoperation rates were 13%, 25%, and 8.1%, respectively. Prior to adopting a different graft product, the overall complication rate was 18.1%; following the change the rate increased to 35%. Complication rates for tissue sealants were 14.8% for no sealant, 18.7% for Tisseel, and 50% for DuraSeal. Nine patients were treated with the combination of Durepair and DuraSeal and this subgroup had a 56% complication rate.

Conclusions. Complication rates after CM-I decompression may be dependent on the dural graft with or without the addition of tissue sealant. The complication rate at the authors’ institution approximately doubled following the adoption of a different graft product. Tissue sealants used in combination with a dural substitute to augment a duraplasty may increase the risk of aseptic meningitis and/or CSF leak. The mechanism of the apparent increased inflammation with this combination remains under investigation.

Neurosurgery 69:112–118, 2011 DOI: 10.1227/NEU.0b013e3182134360

Lumbosacral cutaneous vascular anomalies associated with neural tube defects are frequently described in the literature as ‘‘hemangiomas.’’ The classification system for pediatric vascular anomalies developed by the International Society for the Study of Vascular Anomalies provides a framework to accurately diagnose these lesions.

OBJECTIVE: To apply this classification to vascular cutaneous anomalies overlying myelodysplasias.

METHODS: A retrospective analysis of patients with neural tube defects and lumbosacral cutaneous vascular lesions was performed. All eligible patients had detailed histopathologic analysis of skin and spinal cord/placode lesions. Clinical and radiologic features were analyzed. Conventional histology and GLUT-1 immunostaining were performed to differentiate infantile capillary hemangiomas from capillary vascular malformations.

RESULTS: Ten cases with cutaneous lesions associated with neural tube defects were reviewed. Five lesions were diagnosed as infantile capillary hemangiomas based upon histology and positive GLUT-1 endothelial reactivity. These lesions had a strong association with dermal sinus tracts. No reoperations were required for residual intraspinal vascular lesions, and overlying cutaneous vascular anomalies involuted with time. The remaining 5 lesions were diagnosed as capillary malformations. These occurred with both open and closed neural tube defects, did not involute, and demonstrated enlargement and darkening due to vascular congestion.

CONCLUSION: The International Society for the Study of Vascular Anomalies scheme should be used to describe the cutaneous vascular lesions associated with neural tube defects: infantile capillary hemangiomas and capillary malformations. We advocate that these lesions be described as ‘‘vascular anomalies’’ or ‘‘stains’’ pending accurate diagnosis by clinical, histological, and immunohistochemical evaluations.

Neurosurg Focus 31 (1):E1, 2011. DOI: 10.3171/2011.5.FOCUS1183

The aim of this paper is to provide a comprehensive review of clinical, imaging, and histopathological features, as well as operative and nonoperative management strategies in patients with Rathke cleft cysts (RCCs).

A literature review was performed to identify previous articles that reported surgical and nonsurgical management of RCCs.

Rathke cleft cysts are often incidental lesions found in the sellar and suprasellar regions and do not require surgical intervention in the majority of cases. In symptomatic RCCs, the typical clinical presentation includes headache, visual loss, and/or endocrine dysfunction. Visual field testing and endocrine laboratory studies may reveal more subtle deficiencies associated with RCCs. When indicated, the transsphenoidal approach typically offers the least invasive and safest method for treating these lesions.

Various surgical strategies including cyst wall resection, intralesional alcohol injection, and sellar floor reconstruction are discussed. Although headache and visual symptoms frequently improve after surgical drainage of RCCs, hypopituitarism and diabetes insipidus are less likely to do so.

A subset of more aggressive, atypical RCCs associated with pronounced clinical symptoms and higher recurrence rates is discussed, as well as the possible relationship of these lesions to craniopharyngiomas.

Rathke cleft cysts are typically benign, asymptomatic lesions that can be monitored. In selected patients, transsphenoidal surgery provides excellent rates of improvement in clinical symptoms and long-term cyst resolution. Complete cyst wall resection, intraoperative alcohol cauterization, and sellar floor reconstruction in the absence of a CSF leak are not routinely recommended.

Neurosurg Rev. DOI 10.1007/s10143-011-0327-4

Benign external hydrocephalus in infants, characterized by macrocephaly and typical neuroimaging findings, is considered as a self-limiting condition and is therefore rarely treated. This review concerns all aspects of this condition: etiology, neuroimaging, symptoms and clinical findings, treatment, and outcome, with emphasis on management. The review is based on a systematic search in the Pubmed and Web of Science databases. The search covered various forms of hydrocephalus, extracerebral fluid, and macrocephaly. Studies reporting small children with idiopathic external hydrocephalus were included, mostly focusing on the studies reporting a long-term outcome.

A total of 147 studies are included, the majority however with a limited methodological quality. Several theories regarding pathophysiology and various symptoms, signs, and clinical findings underscore the heterogeneity of the condition. Neuroimaging is important in the differentiation between external hydrocephalus and similar conditions. A transient delay of psychomotor development is commonly seen during childhood. A long-term outcome is scarcely reported, and the results are varying.

Although most children with external hydrocephalus seem to do well both initially and in the long term, a substantial number of patients show temporary or permanent psychomotor delay. To verify that this truly is a benign condition, we suggest that future research on external hydrocephalus should focus on the long-term effects of surgical treatment as opposed to conservative management.

Neurosurgery 68:950–956, 2011 DOI: 10.1227/NEU.0b013e318208f1f3

Hydrocephalus affects 7% to 10% of patients with Chiari I malformation (CIM). It can be successfully treated by endoscopic third ventriculostomy (ETV), possibly improving related CIM and syringomyelia.

OBJECTIVE: To confirm the effectiveness of ETV in the management of Chiari-related hydrocephalus and symptoms and to estimate the posterior cranial fossa volume (PCFV) to find the possible reasons for the success or failure of ETV.

METHODS: Fifteen patients (11 children and 4 adults) underwent ETV for hydrocephalus associated with CIM (syringomyelia was present in 6 patients). Preoperative PCFV, posterior fossa brain volume (PFBV), and PFBV/PCFV ratio were calculated in the last 12 patients in the series by a magnetic resonance imaging–based computerized method.

RESULTS: All patients had symptomatic hydrocephalus (mean third ventricle diameter, 14.1 mm). Mean tonsillar ectopia was 12.7 mm. Postoperatively, hydrocephalus symptoms improved in all cases (mean third ventricle diameter, 8.3 mm); signs and symptoms of CIM and syringomyelia resolved or improved in all patients, although the malformation remained radiologically stable in half of the patients (postoperative mean tonsillar ectopia, 8.8 mm). There were no remarkable differences between cases and controls with regard to PCFV and PFBV. The PFBV/PCFV ratio was comparable in pediatric cases and controls but not among adult patients, suggesting a PCF overcrowding in the controls.

CONCLUSION: ETV is an effective treatment for hydrocephalus associated with CIM. It is successful in improving CIM and syringomyelia in patients with no overcrowding (mainly in children) or with reversible overcrowding of the PCF (mainly in adults).

J Neurosurg Pediatrics 7:000–000, 2011.DOI: 10.3171/2011.1.PEDS10341

The natural history of untreated Chiari malformation Type I (CM-I) is poorly defined. The object of this study was to investigate outcomes in pediatric patients with CM-I who were followed up without surgical intervention.

Methods. The authors retrospectively reviewed 124 cases involving patients with CM-I who presented between July 1999 and July 2008 and were followed up without surgery. The patients ranged in age from 0.9 to 19.8 years (mean 7 years). The duration of follow-up ranged from 1.0 to 8.6 years (mean 2.83 years). Imaging findings, symptoms, and findings on neurological examinations were noted at presentation and for the duration of follow-up.

Results. The mean extent of tonsillar herniation at presentation was 8.35 mm (range 5–22 mm). Seven patients had a syrinx at presentation. The syrinx size did not change in these patients on follow-up imaging studies. No new syrinxes developed in the remaining patients who underwent subsequent imaging. The total number of patients with presenting symptoms was 81. Of those 81 patients, 67 demonstrated symptoms that were not typical of CM-I. Of the 14 patients with symptoms attributed to CM-I, 9 had symptoms that were not severe or frequent enough to warrant surgery, and surgery was recommended in the remaining 5 patients. Chiari malformation Type I was also diagnosed in 43 asymptomatic patients who had imaging studies performed for various reasons. No new neurological deficits were noted in any patient for the duration of follow-up.

Conclusions. The majority of patients with CM-I who are followed up without surgery do not progress clinically or radiologically. Longer follow-up of this cohort will be required to determine if symptoms or new neurological findings develop over the course of many years.

Neurosurgery 68:788–803, 2011 DOI: 10.1227/NEU.0b013e318207ac91

Intracranial cysts containing cerebrospinal fluid (CSF) may be developmental or acquired.

OBJECTIVE: To analyze the results of endoscopic neurosurgery in the management of intracranial CSF cysts.

METHODS: In a 7-year period, 64 consecutive patients underwent endoscopic neurosurgery for CSF cysts. Group 1 consisted of 13 patients with acquired cysts; group 2 included 51 patients with developmental cysts. In all cases, the cyst walls were fenestrated through small burr holes with frameless guided operative endoscopes. Follow-up ranged from 1 to 6 years (mean, 3.4 years).

RESULTS: There were no mortality and no permanent morbidity, apart from a patient (1.6%) who remained neurologically intact but required ventriculoperitoneal shunting because of intraoperative hemorrhage. The planned fenestrations could be performed in all patients except 2, owing to thick, opaque cyst walls. In group 1, 6 patients fully recovered and remained intact throughout the follow-up, whereas 7 improved but had various degrees of neurological disabilities that were related to their initial diseases. Radiological results were excellent in all cases. In group 2, there were 7 asymptomatic patients who remained unchanged and 44 ‘‘symptomatic’’ patients: 40 (91%) clinically improved, 4 (9%) remained unchanged, and none worsened. Cyst size decreased in 37 patients (74%) and remained unchanged in 13 (26%).

CONCLUSION: In this series, patients of different ages, harboring cysts of various sizes and locations, could be satisfactorily treated with endoscopic neurosurgery.

J Neurosurg Pediatrics 7:000–000, 2011.DOI: 10.3171/2010.12.PEDS10359

The authors present their experience in the surgical treatment of metopic synostosis by orbital bandeau remodeling and frontal bone rotation. The pitfalls and advantages of the surgical technique are discussed, along with the long-term clinical results in 48 consecutive cases.

Methods. Forty-eight consecutive patients in whom trigonocephaly was diagnosed between 1990 and 2009 were treated with frontal bone rotation and frontoorbital bandeau remodeling. Of these patients, 38 (79%) were boys and 10 (21%) were girls. The age at the time of surgical treatment ranged between 4 and 42 months (mean ± SD 11.4 ± 8.7 months). The average follow-up period was 5.5 ± 4.2 years (range 5 months–19 years). The preoperative and latest postoperative photographs of the patients were evaluated for the following features: 1) shape of the forehead; 2) hypotelorism; and 3) temporal depression. Scores of 0, 1, or 2 were assigned for each item: 0 was normal, 1 meant moderate deformity, and 2 denoted severe deformity.

Results. In the early postoperative period, no complications were documented. The average hospitalization period was 4 days. Follow-up radiographs or 3D CT scans were obtained at regular intervals. The mean preoperative scores for the evaluated items were 1.38 ± 0.49 for the shape of the forehead, 1.33 ± 0.48 for hypotelorism, and 1.7 ± 0.46 for the temporal depression. The mean postoperative scores were 0.06 ± 0.24 for the shape of the forehead, 0.21 ± 0.4 for hypotelorism, and 0.67 ± 0.48 for the temporal depression. Overall, the total preoperative score dropped from 4.4 to 0.93 postoperatively (p < 0.05). All the patients were contented with the cosmetic results.

Conclusions. Early detection and treatment of metopic suture synostosis has a significant, favorable influence on the outcomes. Good understanding of the structural abnormality and the pathophysiological mechanisms of the possible complications is very important for performing proper surgical reconstruction.

Childs Nerv Syst.DOI 10.1007/s00381-011-1399-8

Endoscopic cystocisternotomy is one of three surgical methods used to treat middle cranial fossa arachnoid cysts. There is debate about which method is the best.

Objective The aim of this study is to evaluate the effectiveness and safety of endoscopic cystocisternotomy for treatment of arachnoid cysts of the middle cranial fossa.

Methods Thirty-two patients with arachnoid cysts of the middle cranial fossa who had undergone endoscopic cystocisternal fenestration between 2004 and 2009 were studied retrospectively. Data were obtained on clinical and neuroradiological presentation, indications to treat, surgical technique, complications, and the results of clinical and neuroradiological follow-up.

Results Among the 27 patients with symptoms before surgery, 8 had disappearance of symptoms and 17 had improvement of symptoms. The cyst was reduced in size or it completely disappeared in 24 (75%) patients. The incidence rate of complications was 18.8%.

Conclusions Endoscopic cystocisternal fenestration is an effective treatment for symptomatic arachnoid cysts of the middle cranial fossa and should be the initial surgical procedure.