Congenital Obstructive Hydrocephalus Research Articles

P.136 The effectiveness of primary endoscopic third ventriculostomy (ETV) on cognition and gait outcomes in adults with congenital obstructive hydrocephalus (COH)

Background: Endoscopic third ventriculostomy (ETV) has become a treatment of choice for adults with clinically significant chronic obstructive hydrocephalus (COH). We evaluated the impact of ETV on cognition and gait in adults with COH. Methods: We retrospectively analyzed prospectively collected data from patients who underwent ETV as primary treatment for COH. Cognitive testing using the Montreal Cognitive Assessment (MoCA) and Symbol Digit Modalities Test (SDMT) was obtained pre-ETV at three months and one year postoperatively. Gait velocity was assessed using a 10-m walk test at each time point. Results: A total of 51 patients were identified. The mean age was 55±1 years, and 45% of patients were women. Baseline MoCA was 22.6±3.1, which improved to 25.7±3.0 and 26±3.4 at three months and one year, respectively (p<0.001). Half of the patients had a normal MoCA score post-ETV (IQR 26-27 at one year, p<0.001). Gait velocity was significantly improved at three months and 1-year post-ETV (p=0.0036). The cognitive and gait improvement one year after ETV was clinically significant. Conclusions: Cognition and gait improved at three months; results were sustained at 12 months post-ETV in adult patients with COH. ETV is an efficacious surgical consideration in this population.

Endoscopic Third Ventriculostomy in the Pediatric Population: Case Series Report

Abstract Objective Hydrocephalus is characterized by multi- or uniloculated ventricular dilatation, and there are differences between the etiology and therapeutic response of each type. Endoscopic third ventriculostomy (ETV) is indicated for the treatment of obstructive hydrocephalus, with a reported efficacy between 50% and 76%. Reduced efficacy of the procedure has been demonstrated in communicating hydrocephalus due to multifactorial pathogenesis, and, in patients with myelomeningocele, its efficacy ranges from 15% to 20% at birth. The present study aims to compare the efficacy of ETV in the treatment of congenital obstructive hydrocephalus (COH) and acquired obstructive hydrocephalus (AOH) in the pediatric population. Methods A retrospective study of 169 endoscopic surgeries performed by the senior author in two institutions, one public (Hospital João XXIII, Belo Horizonte, Minas Gerais) and another private (Hospital Felício Rocho, Belo Horizonte, Minas Gerais), in the period from 2003 a 2020. From the selection of 169 patients, only 77 cases fit the age profile ≤12 years of the present study. Of these, 46 were male, and the age range ranged from 10 days to 12 years. The study included multiple etiologies, which were divided into 2 groups, 34 related to COH, and 43 to AOH. Results Regarding the cases of COH, 22 were submitted to ETV as the main treatment, with 14 (63.63%) effective and 8 (36.36%) ineffective procedures. As for the cases of AOH, 13 patients underwent ETV, and 8 (61.53%) procedures were effective, and 5 (38.46%), ineffective. Conclusions Through the calculation of the p-value of 0.49, we concluded that it cannot stated that the efficacy of ETV is greater in COH than in AOH.

Echoencephalography of encephalopathy due to congenital lymphocytic choriomeningitis virus.

AbstractCongenital lymphocytic choriomeningitis virus (LCMV) infection is a transient intrauterine viral infection with selective teratogenicity depending on the timing of the primary maternal infection. LCMV is cleared from the body of the fetus after the acute phase of illness and, in most cases, has lost its virulence at the time of birth. LCMV competes with extracellular matrix proteins for its tropism toward heavily glycosylated alpha‐dystroglycan. In the first trimester, while tropism toward heart myoblasts is high, intrauterine infection (IUI) can lead to miscarriage or fetal demise. Later in pregnancy, LCMV becomes neurotropic with tropism toward retina and brain. Most often systemic symptoms are subtle or absent at the time of birth. The timing of the IUI determines the neuroteratogenic phenotypes of congenital LCMV infection. IUI that occurs early during gestation can lead to isolated cerebellar dysgenesis and hypoplasia. When IUI occurs during neural radial migration, echoencephalography shows defective cerebral opercularization, intracranial calcifications at the gray‐white matter junction, enlarged extra‐axial subarachnoid space, and cortical dysplasia. When IUI occurs after the completion of insular opercularization (late second trimester), echoencephalography shows extensive cystic periventricular leukomalacia with bi‐occipital porencephaly and mild defects in gyrogenesis. A late gestation IUI induces aseptic LCMV meningitis with occlusion of the aqueduct of Sylvius, leading to congenital obstructive hydrocephalus. Congenital LCMV remains underdiagnosed as clinical manifestations are predominantly neurologic. As echoencephalography remains the preferred screening strategy for detecting neonatal central nervous system pathology, prior knowledge of echoencephalography of congenital LCMV may facilitate its recognition, prompting a serological evaluation.

Mis-diagnosed giant ovarian cyst and ventriculoperitoneal shunt malfunction

Abdominal pseudocysts are common complications of ventriculoperitoneal shunt (VPS). We report the case of a 37-year-old woman treated by VPS for congenital obstructive hydrocephalus, who presented shunt dysfunction related to a voluminous abdominal cyst initially diagnosed as cerebrospinal fluid pseudocyst. The cyst was drained and the VPS was removed after endoscopic third ventriculocisternostomy (ETV). A few months later, a large new abdominal cyst appeared and was operated on. Diagnosis was rectified as massive ovarian mucinous cystadenoma. In any intra-abdominal cyst, differential diagnoses need considering to avoid mis-diagnosis in shunted patients, especially if the cyst is very large. The etiology of the hydrocephalus should also be investigated in case of shunt dysfunction. Even in case of longstanding shunt, ETV can be an alternative to shunt revision surgery in obstructive hydrocephalus, enabling VPS withdrawal and treatment of the hydrocephalus.

Fetal therapy for congenital hydrocephalus-where we came from and where we are going.

Despite unfavorable outcomes during the early experience with in utero intervention for congenital hydrocephalus, improvements in prenatal diagnosis, patient selection, and fetal surgery techniques have led to a renewed interest in fetal intervention for congenital hydrocephalus. Research studies and clinical evidence shows that postnatal cerebrospinal fluid diversion to release intraventricular pressure and cerebral mantle compression usually arrives late to avoid irreversible brain damage. Make sense to decompress those lateral ventricles as soon as possible during the intrauterine life when hydrocephalus is antenatally detected. We present a historical review of research in animal models as well as clinical experience in the last decades, traveling until the last years when some research fetal therapy groups have made significant progress in recapitulating the prenatal intervention for fetuses with congenital obstructive hydrocephalus.

Neocortical tissue recovery in severe congenital obstructive hydrocephalus after intraventricular administration of bone marrow-derived mesenchymal stem cells

BackgroundIn obstructive congenital hydrocephalus, cerebrospinal fluid accumulation is associated with high intracranial pressure and the presence of periventricular edema, ischemia/hypoxia, damage of the white matter, and glial reactions in the neocortex. The viability and short time effects of a therapy based on bone marrow-derived mesenchymal stem cells (BM-MSC) have been evaluated in such pathological conditions in the hyh mouse model.MethodsBM-MSC obtained from mice expressing fluorescent mRFP1 protein were injected into the lateral ventricle of hydrocephalic hyh mice at the moment they present a very severe form of the disease. The effect of transplantation in the neocortex was compared with hydrocephalic hyh mice injected with the vehicle and non-hydrocephalic littermates. Neural cell populations and the possibility of transdifferentiation were analyzed. The possibility of a tissue recovering was investigated using 1H High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance (1H HR-MAS NMR) spectroscopy, thus allowing the detection of metabolites/osmolytes related with hydrocephalus severity and outcome in the neocortex. An in vitro assay to simulate the periventricular astrocyte reaction conditions was performed using BM-MSC under high TNFα level condition. The secretome in the culture medium was analyzed in this assay.ResultsFour days after transplantation, BM-MSC were found undifferentiated and scattered into the astrocyte reaction present in the damaged neocortex white matter. Tissue rejection to the integrated BM-MSC was not detected 4 days after transplantation. Hyh mice transplanted with BM-MSC showed a reduction in the apoptosis in the periventricular neocortex walls, suggesting a neuroprotector effect of the BM-MSC in these conditions. A decrease in the levels of metabolites/osmolytes in the neocortex, such as taurine and neuroexcytotoxic glutamate, also indicated a tissue recovering. Under high TNFα level condition in vitro, BM-MSC showed an upregulation of cytokine and protein secretion that may explain homing, immunomodulation, and vascular permeability, and therefore the tissue recovering.ConclusionsBM-MSC treatment in severe congenital hydrocephalus is viable and leads to the recovery of the severe neurodegenerative conditions in the neocortex. NMR spectroscopy allows to follow-up the effects of stem cell therapy in hydrocephalus.

Kleeblattsch\xe4del skull presenting in concert with Pfeiffer syndrome

BackgroundKleeblattschädel skull, also known as the cloverleaf is a complex synostosis which presents with an enlarged tri-lobar skull resulting temporal bulging and a flat posterior skull, a rare find in the population. This pansynostosis is associated with other congenital syndromes which include Crouzon, Pfeifer, and Carpenter’s. The genetic disorder Pfeiffer syndrome results from skull bones’ premature fusion characterized by deformities of the hand and feet. The author reports a 10-month-old girl who presented with a tri-lobar skull and wide toes which is a significant finding of Pfeiffer syndrome.Case presentationA 10-month-old girl presents with congenital obstructive hydrocephalus due to cloverleaf skull with horizontally enlarged head and large fontanelles. The child also had mid-facial hypoplasia and pre-axial bilateral lower limb polydactyly. Wide toes were also observed, an indicator of Pfeiffer’s Syndrome. Computed tomography (CAT) scans grossly abnormal craniofacial appearances, with premature closure of the sagittal suture giving a cloverleaf skull appearance. There was also a significant thinning of the brain parenchyma.ConclusionPremature closure of sutures leads to a forced growth in a plane perpendicular to the closed suture. Cloverleaf deformity can present with multiple syndromes such as Pfeiffer’s. This leads to gross alteration of the skull with potential underlying morbidity.

Corrigendum: Dusp16 Deficiency Causes Congenital Obstructive Hydrocephalus and Brain Overgrowth by Expansion of the Neural Progenitor Pool.

[This corrects the article on p. 372 in vol. 10, PMID: 29170629.].

Factors of endoscopic third ventriculostomy efficacy in infants with obstructive hydrocephalus under one year of age

To study the factors affecting the efficacy of ETV. A total of 88 ETVs were performed in infants under one year of age in our clinic in 2012-2016. Subsequently, 43 (48.9%) children underwent CSF shunting, and one child underwent repeated ETV. The mean time until the appearance of clinical signs of stoma closure was 3.9 months (116 days). The procedure was most effective in the case of congenital obstructive hydrocephalus (64.5% of successful operations) and also in children over the age of 6 months (63.6% of successful operations). The efficacy in post-hemorrhagic hydrocephalus was 40%. The efficacy in grade 4 intraventricular hemorrhage was lowest and amounted to 25%. The total efficacy of ETV in children under one year of age in our study was 51.1%. In the case of congenital obstructive hydrocephalus, the efficacy of ETV is maximal and amounts to 64.5%. To achieve the highest efficacy of ETV in infants under one year of age, careful selection of patients at the preoperative stage is necessary, with allowance for many factors affecting treatment outcome.

Dusp16 Deficiency Causes Congenital Obstructive Hydrocephalus and Brain Overgrowth by Expansion of the Neural Progenitor Pool.

Hydrocephalus can occur in children alone or in combination with other neurodevelopmental disorders that are often associated with brain overgrowth. Despite the severity of these disorders, the molecular and cellular mechanisms underlying these pathologies and their comorbidity are poorly understood. Here, we studied the consequences of genetically inactivating in mice dual-specificity phosphatase 16 (Dusp16), which is known to negatively regulate mitogen-activated protein kinases (MAPKs) and which has never previously been implicated in brain development and disorders. Mouse mutants lacking a functional Dusp16 gene (Dusp16−/−) developed fully-penetrant congenital obstructive hydrocephalus together with brain overgrowth. The midbrain aqueduct in Dusp16−/− mutants was obstructed during mid-gestation by an expansion of neural progenitors, and during later gestational stages by neurons resulting in a blockage of cerebrospinal fluid (CSF) outflow. In contrast, the roof plate and ependymal cells developed normally. We identified a delayed cell cycle exit of neural progenitors in Dusp16−/− mutants as a cause of progenitor overproliferation during mid-gestation. At later gestational stages, this expanded neural progenitor pool generated an increased number of neurons associated with enlarged brain volume. Taken together, we found that Dusp16 plays a critical role in neurogenesis by balancing neural progenitor cell proliferation and neural differentiation. Moreover our results suggest that a lack of functional Dusp16 could play a central role in the molecular mechanisms linking brain overgrowth and hydrocephalus.

The Burden of Ionizing Radiation Studies in Children with Ventricular Shunts

To quantify the number of shunt-related imaging studies that patients with ventricular shunts undergo and to calculate the proportion of computed tomography (CT) scans associated with a surgical intervention. Retrospective longitudinal cohort analysis of patients up to age 22 years with a shunt placed January 2002 through December 2003 at a pediatric hospital. Primary outcome was the number of head CT scans, shunt series radiograph, skull radiographs, nuclear medicine, and brain magnetic resonance imaging studies for 10 years following shunt placement. Secondary outcome was surgical interventions performed within 7 days of a head CT. Descriptive statistics were used for analysis. Patients (n = 130) followed over 10 years comprised the study cohort. The most common reasons for shunt placement were congenital hydrocephalus (30%), obstructive hydrocephalus (19%), and atraumatic hemorrhage (18%), and 97% of shunts were ventriculoperitoneal. Patients underwent a median of 8.5 head CTs, 3.0 shunt series radiographs, 1.0 skull radiographs, 0 nuclear medicine studies, and 1.0 brain magnetic resonance imaging scans over the 10 years following shunt placement. The frequency of head CT scans was greatest in the first year after shunt placement (median 2.0 CTs). Of 1411 head CTs in the cohort, 237 resulted in surgical intervention within 7 days (17%, 95% CI 15%-19%). Children with ventricular shunts have been exposed to large numbers of imaging studies that deliver radiation and most do not result in a surgical procedure. This suggests a need to improve the process of evaluating for ventricular shunt malfunction and minimize radiation exposure.

Restricted Pax3 Deletion within the Neural Tube Results in Congenital Hydrocephalus.

Congenital hydrocephalus is a common birth-defect whose developmental origins are poorly understood. Pax3-null mutants show defects in myogenesis, neural tube closure, neural crest morphogenesis, and heart development that, consequently, results in embryonic lethality. Here we demonstrate that conditional deletion of the mouse Pax3 transcription factor results in fully-penetrant congenital obstructive hydrocephalus. To identify the role of Pax3 during cranial development, we deleted Pax3 within the neuroepithelium (via Pax7−Cre), in the neural crest (via P0-Cre), and in both the neuroepithelium and the neural crest (via Wnt1-Cre). Only conditional mutants generated using Pax7−Cre or Wnt1-Cre developed early onset congenital hydrocephalus due to stenosis of the third ventricle, suggesting that loss of neuroepithelial Pax3 is sufficient to disturb third ventricle morphogenesis. Dilation of lateral ventricles occurs as early as E14.5, and lineage-mapping revealed that the neuroepithelial cells in the conditional mutants are present, but fail to undergo normal differentiation at the stenotic site. Concomitant with a narrowing of the mutant third ventricle, we detected ectopic apoptosis, reduced proliferation, and abnormal β-catenin localization. Furthermore, consistent with the overlapping expression pattern of Pax3 and Pax7 in early cranial neuroepithelium, we demonstrated a combinatorial role, as compound Pax3/Pax7 heterozygotes display partially-penetrant congenital hydrocephalus. These murine data provide an experimental paradigm underpinning clinical observations of the presence of PAX3 mutations in some hydrocephalic patients.

Timing of endoscopic third ventriculostomy in pediatric patients with congenital obstructive hydrocephalus: assessment of neurodevelopmental outcome and short-term operative success rate

The purpose of this study was to determine the impact of early (⩽6months old), midterm (6–12months old) and late (>12months old) endoscopic third ventriculostomy (ETV) on the operative success rate and postoperative neurodevelopmental outcome of children with congenital obstructive hydrocephalus. We divided 63 children into three groups according to whether they underwent early, midterm or late ETV. Their preoperative developmental quotient (DQ) was assessed using the Gesell developmental diagnosis schedule (GDDS). Three and 6months after the initial procedure, GDDS was used to obtain postoperative DQ from two assessments (blinded and non-blinded). Meanwhile, two observers studied the operative success rate of initial ETV. There were no substantial differences between blinded and non-blinded assessments. The success rate of early ETV was only 20.8%. By contrast, this rate was 55% and 73.7% for midterm and late ETV, respectively. Before operation, we observed severe developmental abnormalities in all children (DQ score<40). However, children in midterm and late ETV groups achieved improvement after the operation, which was particularly remarkable in late ETV group. Six months after the first surgery, 16 (84.2%) children in the late ETV group, nine (45%) in the midterm ETV group and four (16.7%) in the early ETV group had moderate developmental disability. Nevertheless, overall prognosis for the three groups was not optimistic. There were no children with mild neurodevelopmental disability or normal function. Our data confirmed that age is a determinant for ETV effectiveness and overall prognosis.

Concomitant Inactivation of Foxo3a and Fancc or Fancd2 Reveals a Two-Tier Protection from Oxidative Stress-Induced Hydrocephalus

This study seeks at investigating the cause of hydrocephalus, and at identifying therapeutic targets for the prevention of hydrocephalus. In this study, we show that inactivation of the Foxo3a gene in two mouse models of Fanconi anemia (FA) leads to the development of hydrocephalus in late embryonic stage and after birth. More than 50% of Foxo3a(-/-) Fancc(-/-) or Foxo3a(-/-) Fancd2(-/-) mice die during embryonic development or within 6 months of life as a result of hydrocephalus characterized by cranial distortion, dilation of the ventricular system, reduced thickness of the cerebral cortex, and disorganization of the ependymal cilia and subcommissural organ. Combined deficiency of Foxo3a and Fancc or Fancd2 not only impairs the self-renewal capacity but also markedly increases the apoptosis of neural stem and progenitor cells (NSPCs), leading to defective neurogenesis. Increased accumulation of reactive oxygen species (ROS) and subsequently de-regulated mitosis and ultimately apoptosis in the neural stem or progenitor cells is identified as one of the potential mechanisms of congenital obstructive hydrocephalus. The work unravels a two-tier protective mechanism for preventing oxidative stress-induced hydrocephalus. The deletion of Foxo3a in FA mice increased the accumulation of ROS and subsequently de-regulated mitosis and ultimately apoptosis in the NSPCs, leading to hydrocephalus development.

Extrahepatic Biliary Atresia With Cholestatic Jaundice and Hydrocephalus

Biliary atresia is the most frequent cause of surgical jaundice in the late neonatal age group. Congenital extrahepatic biliary atresia and obstructive hydrocephalus is a rare association and not reported earlier in literature. We report a 2-month-old baby who presented with yellow discoloration of skin, high colored urine and clay colored stools since 20 days of life. Head size was apparently looking large with dilated veins over the scalp. The baby was diagnosed and treated as extrahepatic biliary atresia that led to cholestatic jaundice and cerebral aqueductal stenosis with hydrocephalus. Int J Clin Pediatr. 2014;3(1):16-18 doi: http://dx.doi.org/10.14740/ijcp137w

Success rate of endoscopic third ventriculostomy in infants below six months of age with congenital obstructive hydrocephalus (a preliminary study of eight cases)

Aim:In this study, we were assessing the outcome of Endoscopic Third Ventriculostomy (ETV) in infants below six months of age in cases of congenital obstructive hydrocephalus.Materials and Methods:The study was done prospectively on eight cases of obstructive hydrocephalus in infants younger than six months of age to assess the success rate of ETV as a primary treatment for hydrocephalus in this age group; in cases of evident failure, a ventriculo-peritoneal (VP) shunt was applied.Results:Despite eliminating the factors suggested as causes of ETV failure in infants below six months; the type, as with the communicating hydrocephalus, the thickness of the third ventricular floor, history of previous intracranial hemorrhage or central nervous system infection, still the success rate did not exceed 12.5%.Conclusions:The complication rate following ETV was low in comparison to the high frequency (20–80%) and seriousness of the possible postoperative complications following VP shunt with a significant decrease in the quality of patients’ lives. Hence the decision-making as well as the parental counselling were in a trial to estimate the ETV success or the need to perform a shunt in the treatment of obstructive hydrocephalus.

Little Albert: A neurologically impaired child.

Evidence collected by Beck, Levinson, and Irons (2009) indicates that Albert B., the "lost" infant subject of John B. Watson and Rosalie Rayner's (1920) famous conditioning study, was Douglas Merritte (1919-1925). Following the finding that Merritte died early with hydrocephalus, questions arose as to whether Douglas's condition was congenital, rather than acquired in 1922, as cited on his death certificate. This etiology would imply that "Little Albert" was not the "healthy" and "normal" infant described by Watson and numerous secondary sources. Detailed analyses of Watson's (1923) film footage of Albert suggested substantial behavioral and neurological deficits. The anomalies we observed on film of Albert B. are insufficiently explained by his hospital upbringing but are consistent with findings from newly discovered medical records of Douglas Merritte. These documents revealed that the infant suffered from congenital obstructive hydrocephalus, iatrogenic streptococcal meningitis/ventriculitis, and retinal and optic nerve atrophy. The medical history also indicates that Albert's sessions with Watson occurred during periods when Douglas's clinical course was relatively stable. Further inquiries found ample sources of information available to Watson that would have made him aware of Douglas/Albert's medical condition at the times he tested the baby. Experimental ethics, Watson's legacy, and the Albert study are discussed in light of these new findings. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

Sporadic obstructive hydrocephalus in Aqp4 null mice

Aquaporin-4 (Aqp4) is a water transport protein expressed in glia and ependymocytes in brain. We report here the unexpected occurrence of severe obstructive hydrocephalus in a random subset of Aqp4 knockout mice. Of 612 Aqp4 knockout mice produced by heterozygote-heterozygote or knockout-knockout breedings, 9.6% of offspring manifested progressive encephalomegaly. Encephalomegaly was never seen in wild-type or Aqp4 heterozygous mice. Examination of the subset encephalomegalic mice revealed marked triventricular hydrocephalus (lateral ventricle size approximately 500 mm(3)), elevated intracranial pressure (19 +/- 3 vs. 6.1 +/- 0.6 mm Hg), and death by age 6 weeks, with a median survival of 28 days. Intraventricular dye injection studies revealed total obstruction of the cerebral aqueduct. Evans blue extravasation studies indicated an intact blood-brain barrier in the hydrocephalic mice. Brain histology revealed reduced ventricular size and ependymocyte disorganization in some nonhydrocephalic Aqp4 null mice. Our studies establish Aqp4 deletion as a predisposing factor for the development of congenital obstructive hydrocephalus in mice. We suggest that AQP4 polymorphisms might also contribute to the development of aqueduct stenosis in humans.

ENG findings of shunt-treated hydrocephalus in children

Thirty-eight hydrocephalic children (mean age 11.5 years; range 5.1–17.9) were examined on average 7.9 years after initial shunting. The etiology of the hydrocephalus was divided into 5 groups: perinatal intraventricular hemorrhage 14, congenital obstructive hydrocephalus 14, central nervous system infections 4, intracranial cysts 3, and intracranial anomalies 3 children. Electronystagmographic (ENG) examination included recording of spontaneous and positional nystagmus, the pendular eye tracking test, saccadic eye movements, optokinetic and caloric reactions. Only 5 children (13%) had a normal ENG. Thirty-one children (82%) had ENG pathology of the central type and 12 (44%) of the 27 successfully studied had pathological caloric reactions. Ten children (26%) had a combination of both central and vestibular pathology. There was no statistical difference between the boys and the girls or between different etiological groups. The high prevalence of vestibular pathology among these hydrocephalic children may be relevant to their impaired motor performance, because only 7 (18%) of the children studied exhibited normal motor performance in the neurological tests.

Audiological findings of shunt-treated hydrocephalus in children

47 hydrocephalic children (mean age 10.4 years) were examined on average 7.9 years after initial shunting. The etiology of hydrocephalus was classified into 5 groups as follows: perinatal intraventricular hemorrhage 19, congenital obstructive hydrocephalus 15, intracranial cysts 5, severe intracranial anomalies 4 and central nervous system infections 4 children. Audiological examination included pure-tone audiometry, tympanometry, registration of stapedius reflex thresholds and adaptation. A sensorineural high-frequency hearing loss was found in 18 (38%) of 47 examined shunt-treated hydrocephalic children, and 11 of the losses could be classified as the retrocochlear type. The differences of the mean hearing thresholds between the etiological groups of childhood hydrocephalus were minimal.