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Triantafyllos Bouras and Spyros Sgouros

Object

Endoscopic third ventriculostomy (ETV) is an established treatment for hydrocephalus. Most studies focus on success rate, and complications are insufficiently documented. The aim of this study was to perform a systematic review of ETV complications.

Methods

A Medline search discovered 34 series of ETV with detailed complications reports (17 series involving exclusively pediatric patient populations, 6 series involving exclusively adults, and 11 series involving mixed adult and pediatric populations).

Results

The analysis included 2985 ETVs performed in 2884 patients. The cause of hydrocephalus was aqueductal stenosis in 29.3% of patients, tumor in 37.6%, meningomyelocele in 7.6%, cysts in 2.6%, cerebellar infarct in 0.9%, Dandy-Walker malformation in 0.6%, and Chiari malformation Type I in 0.4%; 7.4% of the patients had posthemorrhagic hydrocephalus, 1.8% had postinfectious hydrocephalus, and 1.2% had normal pressure hydrocephalus. Hydrocephalus was due to other causes in 1.3% of cases and the cause was not reported in 9.8%. The overall complication rate was 8.5%. The rate of permanent morbidity was 2.38%; the rate of permanent neurological complications was 1.44% (hemiparesis, gaze palsy, memory disorders, altered consciousness), and the rate of permanent hormonal morbidity was 0.94% (diabetes insipidus, weight gain, precocious puberty). The rate of intraoperative hemorrhage rate was 3.7%; the rate of severe intraoperative hemorrhage was 0.6% (including a 0.21% rate of basilar rupture). The rate for intraoperative neural injury (thalamic, forniceal, hypothalamic, and midbrain injuries) was 0.24%. Central nervous system infections occurred in 1.81% of cases, CSF leak in 1.61%, and postoperative intracranial hematomas in 0.81% of cases. The early postoperative mortality rate was 0.21% (6 patients died; 2 of sepsis and 4 of hemorrhage). Another 2 children suffered delayed “sudden death” (one after 25 months and the other after 60 months), caused by acute hydrocephalus due to stoma occlusion. There were no significant differences between series involving pediatric or adult patient populations or series with fewer than 100 or more than 100 patients. All reported deaths were in series involving more than 100 patients.

Conclusions

Endoscopic third ventriculostomy can be regarded as a low-complication procedure, with an overall complication rate of 8.5%, permanent morbidity rate of 2.4%, mortality rate of 0.21%, and delayed “sudden death” rate of 0.07%.

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Spyros Sgouros and Susan J. Dipple

Object. Surveys of cerebrospinal fluid (CSF) shunts that have been removed from patients have shown that even when the ventricular catheter is the cause of the obstruction, the valve may be obstructed or underperforming. The aim of this pilot study was to investigate the degradation of shunt valve structure over time due to the deposition of debris. The findings were compared with findings in unused valves.

Methods. Scanning electron microscopy was used to visualize the structures of the valves. The items that were examined included two unused and nine explanted cylindrical medium pressure valves, one unused and six explanted Delta 1.5 valves (PS Medical, Goleta, CA), and one explanted Medos Programmable valve (Codman Johnson & Johnson, LeLocle, Switzerland). The valves were cut open, disassembled, and coated in gold. The areas that were analyzed included the main valve chamber, the diaphragm unit, and the antisiphon device. For areas with abnormal deposits, energy-dispersive x-ray microanalysis was performed to establish the chemical composition of the deposits.

The reference unused valves had smooth surfaces with no deposits in any areas. All explanted valves had extensive deposits in all surveyed areas. The deposits varied from small clusters of crystals to large areas that displayed a cobblestone appearance. In diaphragm valves the deposits extensively affected the surface of the diaphragm and the gap between the diaphragm and the surrounding case, where normally CSF flows; in the Medos valve the deposits affected in the spring and “staircase” unit. Deposits were present as early as 2 weeks after implantation. On some valves there was a complete film covering the entire outlet of the valve, which formed a cast inside the valve stretching from wall to wall. The deposits consisted mostly of sodium and chloride, but occasionally contained calcium. In all infected and some noninfected valves there was a significant peak of carbon, indicating the presence of protein deposits.

Conclusions. It appears that the continuous flow of CSF through shunt valves causes surface deposits of sodium chloride and other crystals on all aspects of the valve, including the outlet pathways. The formation of deposits may be encouraged by the adhesive properties of the materials that constitute the valve parts.

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W. Jerry Oakes

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Spyros Sgouros, Melpomeni Kountouri and Kal Natarajan

Object

The authors sought to establish whether the volume of the posterior fossa in children suffering from Chiari malformation Type I (CM-I) is smaller than normal, as has been suggested previously. They also investigated the role of syringomyelia in posterior fossa development.

Methods

Both posterior fossa volume (PFV) and intracranial volume (ICV) were measured using segmentation techniques on preoperative magnetic resonance images obtained in 42 children who underwent surgery for CM-I (mean age 127 months, range 36–204 months); 25 (59%) of the patients had syringomyelia. The PFV/ICV ratio was calculated to eliminate differential supratentorial growth. Patients who had deformities potentially interfering with skull growth or who had undergone a shunt insertion procedure prior to craniovertebral decompression were excluded. The results were compared with measurements of 51 healthy children using one-way analysis of variance.

In patients with CM-I only, the mean PFV and PFV/ICV ratios were not statistically different than those for healthy children. In patients with both CM-I and syringomyelia (CM-S), the mean PFV and PFV/ICV ratios were statistically smaller than those for healthy children. The ICV was 1383 cm3 in the healthy group, 1459 cm3 in the CM-I only group, and 1400 cm3 in the CM-S group (p = 0.363); the PFV was 186 cm3 in the healthy group, 196 cm3 in the CM-I only group, and 171 cm3 in the CM-S group (p = 0.036); the PFV/ICV ratio was 0.135 in the healthy group, 0.134 in the CM-I only group, and 0.122 in the CM-S group (p = 0.004). These differences were more prominent in the first 10 years of life.

Conclusions

Children with isolated CM-I do not have a PFV smaller than normal, whereas children with both CM-I and syringomyelia have a PFV significantly smaller than normal. This result indicates that the two subgroups may represent different phenotypic expression or even a different pathogenesis.

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Dimitris Kombogiorgas, Kal Natarajan and Spyros Sgouros

Object

In this study, the authors investigated whether preoperative ventricular volume can be used to predict the need for permanent treatment of hydrocephalus in children with posterior fossa medulloblastomas.

Methods

Ventricular volumes were measured on magnetic resonance imaging studies obtained preoperatively and immediately postoperatively in 20 children who had undergone resection for medulloblastomas between 1999 and 2007. Comparison of mean values was performed using the one-way analysis of variance test. The association between ventricular and tumor volume was also investigated.

Results

All patients had obstructive hydrocephalus preoperatively, and 4 patients required postoperative shunt placement. The mean preoperative ventricular volume was 252 ml for those who required shunt placement, and 106 ml for those who did not (p = 0.000). The postoperative ventricular volume was 157 and 78 ml, respectively (p = 0.039), larger than normal in both groups. The mean postoperative and preoperative ratios were 0.69 and 0.70, respectively (p = 0.932). There was no correlation of ventricular volumes with age at operation (older or younger than 3 years), presence of metastasis, or amount of residual tumor. There was a statistical correlation between the preoperative ventricular volume and the tumor volume, related to the need for permanent shunt placement.

Conclusions

Preoperative ventricular volume has predictive value for the later need for shunt placement, but in clinical practice this may be difficult to appreciate because all patients have significant hydrocephalus at presentation. The rate of ventricular size reduction in response to tumor excision does not have predictive value because ventricular volume is related to tumor volume. It appears that the removal of cerebellar medulloblastoma converts hydrocephalus from obstructive to communicating, which requires surgical treatment if it exceeds a certain level of cerebrospinal fluid volume.

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Chris Xenos, Spyros Sgouros and Kalyan Natarajan

Object. The aim of this study was to construct a model of age-related changes in ventricular volume in a group of normal children ages 1 month to 15 years, which could be used for comparative studies of cerebrospinal fluid circulation disorders and cerebral atrophy developmental syndromes.

Methods. A magnetic resonance imaging—based segmentation technique was used to measure ventricular volumes in normal children; each volume was then plotted against the child's age. In addition, intracranial volumes were measured and the ratio of ventricular to intracranial volume was calculated and plotted against age.

The study group included 71 normal children, 39 boys and 32 girls, whose ages ranged from 1 month to 15.3 years (mean 84.9 months, median 79 months). The mean ventricular volume was 21.3 cm3 for the whole group, 22.7 cm3 in boys and 19.6 cm3 in girls (p = 0.062, according to t-tests). The mean ventricular volume at 12 months for the whole group was 17 cm3 (20 cm3 in boys and 15 cm3 in girls), representing 65% of the volume achieved by 15 years of age (87% in boys and 53% in girls). The volume increased by a factor of 1.53, to 26 cm3 (23 cm3 in males and 28 cm3 in females, increase factors of 1.15 and 1.86, respectively) at 15 years of age. The change in ventricular volume with age is not linear, but follows a segmental pattern. These age periods were defined as: 0 to 3, 4 to 6, 7 to 10, and 11 to 16 years. A statistical difference based on sex was only demonstrated in the first 6 years of life. The mean ventricular volume for the first 6-year period was 22.4 cm3 in boys and 15.7 cm3 in girls, and the difference was significant for the two sexes (linear regression analysis for age and sex, significant according to analysis of variance regression at 0.007, p = 0.108 for age, p = 0.012 for sex). Thereafter, there was no significant difference in ventricular volume between boys and girls with further growth. The ratio of ventricular volume to intracranial volume was 0.0175 for the whole group, 0.017 in boys and 0.018 in girls (p = 0.272, according to t-tests). At 12 months of age the ratio was 0.019; it stabilized to 0.015 at 8 years of age, and increased to 0.018 at 15 years of age. No statistical difference based on sex was demonstrated with growth.

Conclusions. The ventricular volume in normal children increases with age by a factor of 1.5; the increase is in a nonlinear segmental pattern. Boys have significantly higher ventricular volumes only in the first 6 years of life. The ventricular/intracranial volume ratio remains stable throughout childhood.

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R. Shane Tubbs and W. Jerry Oakes

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Spyros Sgouros, Melpomeni Kountouri and Kal Natarajan

Object

The goal of this study was to establish whether children with Chiari malformation Type I (CM-I) have abnormal skull base geometry.

Methods

Distances and angles between skull base landmarks were measured on preoperative magnetic resonance images obtained in 30 children (age range 36–204 months) with symptomatic isolated CM-I; 16 of them (53%) had syringomyelia. Comparisons were made with 42 children of similar age who comprised the control group by using one-way analysis of variance.

Results

The angle formed by the crista galli (CG), dorsum sellae (DS), and foramen magnum (FM) was larger than normal in individuals with CM-I than in those without (145° in patients with CM-I but no syringomyelia and 151° in those with CM-I and syringomyelia compared with 135° in controls; p = 0.000). The angle formed by the left internal auditory meatus (IAM), FM, and right IAM was also larger than normal in the patients (122° in patients with CM-I but no syringomyelia and 123° in those with CM-I and syringomyelia compared with 110° in controls; p = 0.001). The angle formed by the anterior clinoid process (ACP), CG, and right ACP was smaller than normal (29° in all patients with CM-I compared with 34° in controls; p = 0.000). The distance between the two IAMs was longer than normal (75 mm in patients with CM-I but no syringomyelia and 63 mm in those with CM-I and syringomyelia compared with 58 mm in controls; p = 0.000). The distance between the two ACPs was shorter than normal in the syringomyelia group (31 mm in patients with CM-I but no syringomyelia and 27 mm in those with CM-I and syrinx compared with 32 mm in controls; p = 0.001). Within the group of patients with CM-I, the DS–FM and left ACP–right ACP distances were smaller in the syringomyelia group (p = 0.009 and p = 0.037, respectively).

Conclusions

Children with CM-I have abnormal geometrical measurements of their entire skull base, not only the posterior fossa, irrespective of presence of syringomyelia. This may indicate a mesodermal defect as a possible cause of the malformation.

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Abhaya V. Kulkarni, James M. Drake, John R. W. Kestle, Conor L. Mallucci, Spyros Sgouros and Shlomi Constantini

Object

The authors recently developed and internally validated the ETV Success Score (ETVSS)—a simplified means of predicting the 6-month success rate of endoscopic third ventriculostomy (ETV) for a child with hydrocephalus, based on age, etiology of hydrocephalus, and presence of a previous shunt. A high ETVSS predicts a high chance of early ETV success. In this paper, they assess the clinical utility of the ETVSS by determining whether long-term survival outcomes for ETV versus shunt insertion are different within strata of ETVSS (low, moderate, and high scores).

Methods

A multicenter, international cohort of children (≤ 19 years old) with newly diagnosed hydrocephalus treated with either ETV (489 patients) or shunt insertion (720 patients) was analyzed. The ETVSS was calculated for all patients. Survival analyses with time-dependent modeling of the hazard ratios were performed.

Results

For the High-ETVSS Group (255 ETV-treated patients, 117 shunt-treated patients), ETV appeared to have a lower risk of failure right from the early postoperative phase and became more favorable with time. For the Moderate-ETVSS Group (172 ETV-treated patients, 245 shunt-treated patients), ETV appeared to have a higher initial failure rate, but after about 3 months the instantaneous risk of ETV failure became slightly lower than shunt failure (that is, the hazard ratio became < 1). For the Low-ETVSS Group (62 ETV-treated patients, 358 shunt-treated patients), the early risk of ETV failure was much higher than the risk of shunt failure, but the instantaneous risk of ETV failure became lower than the risk of shunt failure at about 6 months following surgery (the hazard ratio became < 1).

Conclusions

Across all ETVSS strata, the risk of ETV failure becomes progressively lower compared with the risk of shunt failure with increasing time from the surgery. In the best ETV candidates (ETVSS ≥ 80), however, the risk of ETV failure is lower than the risk of shunt failure very soon after surgery, while for less-than-ideal ETV candidates (ETVSS ≤ 70), the risk of ETV failure is initially higher than the risk of shunt failure and only becomes lower after 3–6 months from surgery. These results need to be confirmed by larger, prospective, and preferably randomized studies.

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Editorial

Prediction, with restriction

Alan R. Cohen