The surface charge of electroactive materials governs cell behaviour through its effect on protein deposition.

The precise mechanisms underlying the cellular response to static electric cues remain unclear, limiting the design and development of biomaterials that utilize this parameter to enhance specific biological behaviours. To gather information on this matter we have explored the interaction of collagen type-I, the most abundant mammalian extracellular protein, with poly(vinylidene fluoride) (PVDF), an electroactive polymer with great potential for tissue engineering applications. Our results reveal significant differences in collagen affinity, conformation, and interaction strength depending on the electric charge of the PVDF surface, which subsequently affects the behaviour of mesenchymal stem cells seeded on them. These findings highlight the importance of surface charge in the establishment of the material-protein interface and ultimately in the biological response to the material. STATEMENT OF SIGNIFICANCE: The development of new tissue engineering strategies relies heavily on the understanding of how biomaterials interact with biological tissues. Although several factors drive this process and their driving principles have been identified, the relevance and mechanism by which the surface potential influences cell behaviour is still unknown. In our study, we investigate the interaction between collagen, the most abundant component of the extracellular matrix, and poly(vinylidene fluoride) with varying surface charges. Our findings reveal substantial variations in the binding forces, structure and adhesion of collagen on the different surfaces, which collectively explain the differential cellular responses. By exposing these differences, our research fills a critical knowledge gap and paves the way for innovations in material design for advanced tissue regeneration strategies.

Spinal cord lipomas: lessons learned in the era of total resection.

PURPOSE: Recent years have seen a paradigm shift towards total/near-total resection in spinal cord lipoma surgery. As this procedure is technically challenging, surgical candidates need to be selected appropriately through accurate image assessment and classification. The purpose of this paper is to describe a surgical series of paediatric spinal cord lipomas, their diagnosis, results and complications. METHODS: We undertook a retrospective review of paediatric patients with spinal cord lipomas who underwent surgery between 2008 and 2022. The variables studied were age, gender, preoperative symptoms according to the Necker Functional Score (NFS), type of lipoma according to Morota's classification, functional and radiological surgical outcomes using the cord-sac ratio (CSR), need for re-operation, complications and follow-up. RESULTS: A total of 25 patients (average age 36 months) underwent surgery. According to Morota's classification, MRI showed 13 type 1 lipomas, two type 2, two type 3 and eight type 4. The preoperative NFS was 16.06, with urological abnormalities being the most frequent manifestation. Total/near-total resection was attempted since 2015. Five patients with type 1 lipoma required re-operation due to clinical deterioration with suspected retethering, all of them with a CSR > 0.3. The series average CSR was 0.417. CONCLUSIONS: This paper highlights the importance of proper classification for a correct surgical approach to obtain favourable results and minimise possible complications. Based on our experience, given our results regarding the percentage of fistulae and retethering rates, we limited radical resection to symptomatic type 1 lipomas. Our future aim is to obtain better CSR rates and to decrease the retethering percentage.

Analysis of the impact of handling and culture on the expansion and functionality of NK cells.

Natural killer (NK) cells are lymphocytes of the innate immune system that play a key role in the elimination of tumor and virus-infected cells. Unlike T cells, NK cell activation is governed by their direct interaction with target cells via the inhibitory and activating receptors present on their cytoplasmic membrane. The simplicity of this activation mechanism has allowed the development of immunotherapies based on the transduction of NK cells with CAR (chimeric antigen receptor) constructs for the treatment of cancer. Despite the advantages of CAR-NK therapy over CAR-T, including their inability to cause graft-versus-host disease in allogenic therapies, a deeper understanding of the impact of their handling is needed in order to increase their functionality and applicability. With that in mind, the present work critically examines the steps required for NK cell isolation, expansion and storage, and analyze the response of the NK cells to these manipulations. The results show that magnetic-assisted cell sorting, traditionally used for NK isolation, increases the CD16+ population of NK cultures only if the protocol includes both, antibody incubation and passage through the isolation column. Furthermore, based on the importance of surface potential on cellular responses, the influence of surfaces with different net surface charge on NK cells has been evaluated, showing that NK cells displayed higher proliferation rates on charged surfaces than on non-charged ones. The present work highlights the relevance of NK cells manipulation for improving the applicability and effectiveness of NK cell-based therapies.

Multicentric and collaborative study of Spanish neurosurgical management of pediatric craniopharyngiomas: S-PedCPG.co.

PURPOSE: To present a descriptive analysis of pediatric craniopharyngiomas (PedCPG) treated in various Spanish hospitals, defining factors related to recurrence and performing a critical analysis of the results. METHODS: We undertook a multicenter retrospective review of PedCPG treated between 2000 and 2017. Data collected included epidemiological variables, clinical and radiological characteristics, goal of first surgery, rate of recurrence and its approach, adjuvant treatment, complications and permanent morbidity. Associations were studied between progression and number of progressions and independent variables. RESULTS: The study involved 69 children from 8 Spanish hospitals. Most of the tumors invaded several intracranial compartments at diagnosis, with the hypothalamus involved in 41.3% of cases. The first treatment strategy was usually gross total resection (GTR) (71%), with some patients treated with radiotherapy or intracystic chemotherapy. The progression rate after first surgery was 53% in a mean follow-up of 88.2 months (range 7-357). In the GTR group 38.8% of tumors recurred, 40% in the group of subtotal resection or biopsy and 93.3% in the cyst fenestration±Ommaya reservoir group. Mortality was 7.2%. Follow-up period, size of the tumor and goal of first surgery were significantly related with progression. CONCLUSIONS: Our results in terms of disease control, hormonal or visual impairment and mortality were acceptable, but there are several areas for improvement. Our short-term goals should be to create a national register of PedCPG, reach a consensus about a treatment algorithm, and improve diagnosis of hypothalamic dysfunction to avoid preventable morbidity.

Neuroendoscopic septostomy in unilateral and bilateral ventricular hydrocephalus.

PURPOSE: This study describes the results of septostomy (SPT) in terms of success and analysis of follow-up in a series of pediatric patients diagnosed with unilateral ventricular hydrocephalus (UHV) and biventricular hydrocephalus (BVH). METHODS: A total of 29 pediatric patients diagnosed with UVH or BVH were included in this study. In UVH, a neuroendoscopic SPT was performed (sometimes accompanied by NEFPFMO). In those diagnosed with BVH, an SPT combined with VPS was carried out. Demographic, etiological, clinical, and diagnostic variables and percentage of treatment success were collected. RESULTS: SPT was successful during follow-up when no VPS was required in UVH and only unilateral VPS was implanted in BVH. At the time of surgery, 16 patients needed a ventriculoperitoneal shunt. The first SPT was successful in 22 patients, requiring a second surgery in 7 patients, from the oncology group diagnosed with BHV. CONCLUSIONS: The surgical management of UVH and BVH still has some disclosure points to be reviewed. However, SPT seems to be a secure, non-traumatic, and efficient procedure.

Association of the Genetic Variation in the Long Non-Coding RNA FENDRR with the Risk of Developing Hypertrophic Cardiomyopathy.

Background: In around 40−60% of Hypertrophic Cardiomyopathy (HCM) cases pathogenic variants are not identified. Our aim was to evaluate the possible association of lncRNAs with the risk of developing HCM. Methods: We sequenced 10 lncRNAs coding genes that have been associated with cardiovascular disease in a discovery cohort (238 HCM patients and 212 controls) by NGS, and genotyped rs74035787 G>A and rs1424019 A>G polymorphism in a validation cohort (962 HCM patients and 923 controls). Finally, we sequenced the FENDRR promoter by Sanger sequencing. Results: We observed by NGS that FENDRR rs39527, rs39529 and rs40384 polymorphisms were significantly associated with HCM in our cohort (p = 0.0284; OR: 0.24, 95%CI: 0.07−0.86). NGS results were confirmed by genotyping rs74035787 polymorphism (p = 0.001; OR:0.38, 95%CI: 0.21−0.66). Moreover, it is also associated when stratification by sex (p = 0.003; OR:0.20, 95%CI: 0.06−0.53), and age (≥50 years old p = 0.001, OR:0.33, 95%CI: 0.16−0.63) Moreover, the risk of HCM in the carriers of the GG genotype of the rs1424019 polymorphism was significantly higher than that of the AA/AG genotypes carriers in the elderly subjects (p = 0.045, OR:1.24, 95%CI: 1.01−1.53). On the other hand, we observed significant differences in the rs74035787 A/rs1424019 G haplotype frequency (p = 0.0035; OR: 0.20, 95%CI: 0.07−0.59). Conclusions: Our study suggested a significant association between FENDRR gene variants and HCM.

FURIN gene variants (rs6224/rs4702) as potential markers of death and cardiovascular traits in severe COVID-19.

Furin is a protease that plays a key role in the infection cycle of SARS-CoV-2 by cleaving the viral proteins during the virus particle assembly. In addition, Furin regulates several physiological processes related to cardio-metabolic traits. DNA variants in the FURIN gene are candidates to regulate the risk of developing these traits as well as the susceptibility to severe COVID-19. We genotyped two functional FURIN variants (rs6224/rs4702) in 428 COVID-19 patients in the intensive care unit. The association with death (N = 106) and hypertension, diabetes, and hyperlipidaemia was statistically evaluated. The risk of death was associated with age, hypertension, and hypercholesterolemia. The two FURIN alleles linked to higher expression (rs6224 T and rs4702 A) were significantly increased in the death cases (odds ratio= 1.40 and 1.43). Homozygosis for the two high expression genotypes (rs6224 TT and rs4702 AA) and for the T-A haplotype was associated with an increased risk of hypercholesterolemia. In the multiple logistic regression both, hypercholesterolemia and the TT + AA genotype were significantly associated with death. In conclusion, besides its association with hypercholesterolemia, FURIN variants might be independent risk factors for the risk of death among COVID-19 patients.

BMP-2 Enhances Osteogenic Differentiation of Human Adipose-Derived and Dental Pulp Stem Cells in 2D and 3D In Vitro Models.

Bone tissue provides support and protection to different organs and tissues. Aging and different diseases can cause a decrease in the rate of bone regeneration or incomplete healing; thus, tissue-engineered substitutes can be an acceptable alternative to traditional therapies. In the present work, we have developed an in vitro osteogenic differentiation model based on mesenchymal stem cells (MSCs), to first analyse the influence of the culture media and the origin of the cells on the efficiency of this process and secondly to extrapolate it to a 3D environment to evaluate its possible application in bone regeneration therapies. Two osteogenic culture media were used (one commercial from Stemcell Technologies and a second supplemented with dexamethasone, ascorbic acid, glycerol-2-phosphate, and BMP-2), with human cells of a mesenchymal phenotype from two different origins: adipose tissue (hADSCs) and dental pulp (hDPSCs). The expression of osteogenic markers in 2D cultures was evaluated in several culture periods by means of the immunofluorescence technique and real-time gene expression analysis, taking as reference MG-63 cells of osteogenic origin. The same strategy was extrapolated to a 3D environment of polylactic acid (PLA), with a 3% alginate hydrogel. The expression of osteogenic markers was detected in both hADSCs and hDPSCs, cultured in either 2D or 3D environments. However, the osteogenic differentiation of MSCs was obtained based on the culture medium and the cell origin used, since higher osteogenic marker levels were found when hADSCs were cultured with medium supplemented with BMP-2. Furthermore, the 3D culture used was suitable for cell survival and osteogenic induction.

Conventional posterior cranial vault expansion: indications and results-review of the literature.

In the late 1980s, craniofacial surgery units reported suboptimal cosmetic results, cranial volume restriction, and intracranial hypertension after anterior cranial vault remodeling in bilateral coronal synostosis associated with severe brachyturricephaly. A possible explanation was a severe associated growth restriction of the posterior calvaria with radiological synostosis at the lambda sutures. "Conventional" or "fixed" posterior cranial vault expansion techniques were developed to address these limitations, sometimes as the first surgical step in a two-staged protocol of total calvarial reconstruction, combined with suboccipital decompression in cases of symptomatic cerebellar tonsillar herniation or, more easily, to resolve the characteristic occipital flattening of lambdoid synostosis. Various surgical approaches have been described; however, the indications for and timing of surgical treatment and postoperative evaluation of results still remain controversial. Although more invasive, conventional posterior cranial vault expansion has proven to be safe and offers a remodeled and protective bony vault immediately after surgery, but the underlying cranial base malformation remained untreated, with implications in the postoperative growth of the facial skeleton. Overcorrection, rigid stabilization, and grafting are also concerns to be addressed.

Shunt Overdrainage: Reappraisal of the Syndrome and Proposal for an Integrative Model.

Although shunt overdrainage is a well-known complication in hydrocephalus management, the problem has been underestimated. Current literature suggests that the topic requires more examination. An insight into this condition is limited by a lack of universally agreed-upon diagnostic criteria, heterogeneity of published series, the multitude of different management options and misunderstanding of relationships among pathophysiological mechanisms involved. We carried out a review of the literature on clinical, radiological, intracranial pressure (ICP), pathophysiological and treatment concepts to finally propose an integrative model. Active prophylaxis and management are proposed according to this model based on determination of pathophysiological mechanisms and predisposing factors behind each individual case. As pathophysiology is progressively multifactorial, prevention of siphoning with gravitational valves or antisiphon devices is mandatory to avoid or minimize further complications. Shunt optimization or transferal and neuroendoscopy may be recommended when ventricular collapse and cerebrospinal fluid isolation appear. Cranial expansion may be useful in congenital or acquired craniocerebral disproportion and shunting the subarachnoid space in communicating venous hydrocephalus and idiopathic intracranial hypertension.

The APOB polymorphism rs1801701 A/G (p.R3638Q) is an independent risk factor for early-onset coronary artery disease: Data from a Spanish cohort.

BACKGROUND AND AIMS: Apoliprotein B (ApoB) has been associated with hypercholesterolemia and ischemic coronary disease. This study was aimed to determine the effect of two APOB gene variants in the risk of developing early-onset coronary artery disease (EO-CAD) in a Spanish population. The association of these polymorphisms with hypercholesterolemia was also analysed. METHODS AND RESULTS: The study involved a total of 889 healthy population controls (397 male) and 790 EO-CAD cases (636 male; EO-CAD was defined as male <60 years and women <65 years). All the patients had at least one vessel with angiography documented atherosclerotic lesion. Patients and controls were genotyped for the APOB variants rs1801701 A/G (p.R3638Q) and rs1367117 C/T (p.T98I). Allele and genotype frequencies were compared between the groups (patients vs. controls, hyper-vs. normo-cholesterolemia) by logistic regression. The rs1801701 was significantly associated with EO-CAD in male (OR = 1.44, 95%CI = 1.05-1.99) and female (OR = 2.22, 95%CI = 1.58-3.14). This SNP was significantly associated with hypercholesterolemia in female, with a trend in male. The association with EO-CAD was independent of hypercholesterolemia (multiple logistic regression). CONCLUSION: A common APOB polymorphism (rs1801701) was an independent risk factor for EO-CAD in our population. The risk-effect was more significant in female than in male.

Quality of life in school-age children with shunt implantation due to neonatal posthemorrhagic hydrocephalus.

PURPOSE: To assess the functional outcome in school-age children shunted in the neonatal period due to post-hemorrhagic hydrocephalus (PHH), using the HOQ-Spanish version (HOQ-sv), and to analyze predictors of quality of life in this group. METHODS: A cross-sectional study was performed between 2015 and 2018. Parents of pediatric patients with PHH attending our neurosurgery outpatient clinic were invited to complete the HOQ-sv and to enroll in the study. Clinical variables regarding the patients' neonatal course and surgical outcome were recorded. A descriptive analysis was done, and independent variables related to the HOQ scores were studied in univariate and multivariate analyses with regression trees. RESULTS: The study comprised a total of 52 patients. The mean overall HOQ score was 0.67 (on a scale from 0 [worse] to 1 [best]). The quality of life for the PHH children at school age was related to perinatal factors (gestational age at birth, time until shunt surgery, length of hospitalization at the time of shunt implantation, and comorbidity), shunt complications (symptomatic overdrainage, number of shunt revisions, and shunt revisions related to infection during the first year after treatment), and clinical background (seizures, spasticity, Gross Motor Function Classification System level or visual impairment). CONCLUSION: HOQ dimension scores in school-age children shunted due to PHH in our center were similar to those of referral centers for other etiologies of pediatric hydrocephalus. Future goals should be the prevention of complications related to worse outcomes at the time of diagnosis and to try to improve shunt performance later.

Cervical myelomeningocele with CSF leakage: a case-based review.

BACKGROUND: The cystic spinal dysraphism of the cervical and upper thoracic region (CDCT) accounts for only 3.9 to 8% of spina bifida cystica lesions. The presence of external cerebrospinal fluid (CSF) leakage is infrequent and very few authors have reported about surgical complications. CASE REPORT: We present the case of a new born diagnosed of CDCT C1-C3 with a stalk of fibrovascular tissue, CSF leakage, hydrocephalus, and type Chiari II malformation, discuss about the chosen surgical technique and the associated complications, and make a review of the literature focusing on the main aspects of CDCT. CONCLUSIONS: The CDCT with a stalk of neuroglial and/or fibrovascular tissue originates from the dorsal surface of the spinal cord and penetrates into a cervical cystic sac. The presence of CSF leakage, hydrocephalus, and/or type Chiari II malformation can influence to decide the most appropriate surgical technique.

Suprasellar ganglioglioma presenting as a middle cerebral artery infarction.

BACKGROUND: Gangliogliomas are a relatively rare neoplasm with a major incidence in the pediatric population. As the temporal lobes are the most common site, patients usually present with seizures. CASE REPORT: We report the case of a 9-year-old child with an extensive suprasellar ganglioglioma presenting with a cerebral infarction due to direct compression of the medium cerebral artery. CONCLUSIONS: Suprasellar lesions can compress adjacent vascular structures, so an accurate diagnosis is necessary for an early treatment.

Shunt independence in paediatric hydrocephalus: our 16-year experience and review.

PURPOSE: Shunt independence remains a matter of debate for neurosurgeons, and little information on this subject is available in the literature. The aims of the study were to analyse the incidence of shunt removal in a series of paediatric patients and to describe our experience with attempts at shunt removal. METHODS: Thirty of 212 paediatric patients shunted between 2000 and 2016 at our institution were studied for shunt independence. Variables related to hydrocephalus aetiology, shunt complications, independence trial peculiarities and follow-up were recorded and a descriptive analysis of the data was performed. RESULTS: Two patients (0.94%) refused to be included in a shunt independence trial and were analysed separately. In the other 28 patients, 29 shunt independence trials were performed, of which 19 (65.52%) were successful, giving a global rate of shunt independence of 8.96% (19/212) in our population. Secondary endoscopic third ventriculostomy was the most frequent type of independence trial and achieved the highest success rate (75%). Spontaneous independence was achieved in just 4/7 cases (57.14%). Planned removal of the shunt in overdrainage cases had a 50% success rate, with transient measures to control intracranial pressure frequently required. CONCLUSIONS: Shunt independence trials should be considered for selected patients in a closely monitored setting. Secondary endoscopic third ventriculostomy at the time of shunt malfunction has the highest success rate whereas planned removal of the shunt in overdrainage is an invasive procedure with more likelihood of failure. Shunt independence should not be presumed.

Genetic variation at the long noncoding RNA H19 gene is associated with the risk of hypertrophic cardiomyopathy.

AIM: The long noncoding RNA H19 and its host micro RNA miR-675 have been found deregulated in cardiac hypertrophy and heart failure tissues. Our aim was to investigate whether the H19 gene variants were associated with the risk of hypertrophic cardiomyopathy (HCM). PATIENTS & METHODS: We genotyped two H19 tag single nucleotide polymorphisms in 405 HCM patients and 550 controls, and sequenced this gene in 100 patients. RESULTS: The rs2107425 C was significantly increased in sarcomere no-mutation patients (n = 225; p = 0.01): CC versus CT + TT, p = 0.017; odd ratios: 1.51. Sequencing of the H19 coding transcript identified two patients heterozygous carriers for a rare variant, rs945977096 G/A, that was absent among the controls. CONCLUSION: Our study suggested a significant association between H19 variants and the risk of developing HCM.

Genetic Variation in the H19-IGF2 Cluster Might Confer Risk of Developing Impaired Renal Function.

The H19-IGF2 imprinted gene region could be implicated in the risk of developing impaired renal function (IRF). Our aim was to determine the association of several common H19-IGF2 variants and IRF in a cohort of elderly healthy individuals. The study involved 675 individuals >65 years of age, 184 with type 2 diabetes mellitus (T2DM), and 105 with IRF (estimated glomerular filtration rate [eGFR] <60). They were genotyped for two common H19 single nucleotide polymorphisms (SNPs) (rs2839698 and rs10732516), one H19-IGF2 intergenic indel (rs201858505), and one indel in the 3'UTR of the IGF2. For the H19 SNPs, we also determined the allele present in the methylated chromosome through genotyping the DNA digested with a methylation-sensitive endonuclease. None of the four H19-IGF2 variants was associated with IRF in our cohort. We found a significantly higher frequency of the 3'UTR IGF2 deletion (D) in the eGFR <60 group (p = 0.01; odds ratio = 1.16, 95% confidence interval = 1.10-2.51). This association was independent of age and T2DM, two strong predictors of IRF. In conclusion, a common indel variant in the 3'UTR of the IGF2 gene was associated with the risk of IRF. This association could be explained by the role of IGF2 in podocyte survival, through regulation of IGF2 expression by differential binding of miRNAs to the indel sequences. Functional studies should be necessary to clarify this issue.

Gene variants in the NF-KB pathway (NFKB1, NFKBIA, NFKBIZ) and their association with type 2 diabetes and impaired renal function.

The NF-kappaB pathway might play a role in the pathogenesis of renal disease and type 2 diabetes (T2DM). Our aim was to determine whether common polymorphisms in NF-kappaB genes were associated with impaired renal function and T2DM in a cohort of healthy elderly individuals. We studied 487 individuals, all Caucasian and aged 65-85 years. A total of 104 (21%) had impaired renal function (estimated glomerular filtration rate, eGFR < 60) and 146 (30%) were classified as diabetics. The genotypes of 4 common variants were determined through PCR-RFLP or fluorescent capillary electrophoresis. The NFKB1 variants were significantly associated with T2DM: rs7667496 p = 0.01, OR = 1.68; and rs28362491 p = 0.02, OR = 1.67. They remained significantly associated in a multiple logistic regression with age, gender, hypertension, body mass index, and cholesterol. There was a trend toward the association of these variants with eGFR < 60. The two NFKB1 variants were in linkage disequilibrium (D' = -0.86), and homozygous for the two non-risk alleles (rs7667496 CC + rs28362491 II), were significantly more common in the non-diabetics (p = 0.02). In our cohort the NFKB1 variation was an independent risk factor for developing T2DM. Additional studies to confirm this association are of special interest, as well as studies to give a functional explanation to the genetic association.

Functional outcome in pediatric hydrocephalus: results of applying the Spanish version of the Hydrocephalus Outcome Questionnaire.

OBJECTIVE The aims of the study were to assess whether the Spanish version of the Hydrocephalus Outcome Questionnaire (HOQ) could be useful for the evaluation and comparison of outcomes in the patients in the authors' region with those in patients in other institutions and to analyze predictors of functional outcome in patients with a shunt. METHODS The authors performed this cross-sectional study between March 2015 and April 2016. All the parents of a pediatric patient with hydrocephalus who attended the Hospital Regional Universitario de Málaga neurosurgery outpatient clinic were invited to enroll in the study and complete the HOQ-Spanish version. Age at diagnosis and at the time of the study, clinical data, shunt complications, and socioeconomic factors were also recorded. A descriptive analysis was performed, and independent variables related to the HOQ scores were studied. RESULTS A total of 132 patients participated in the study (100% participation rate). The mean ages were 16.74 months (range 0-142 months) at diagnosis and 10.45 years (range 5-16 years) at the time of the study. The mean overall HOQ score was 0.68 (on a scale from 0 [worse] to 1.0 [best]). Factors related to a worse quality of life were seizures, motor or visual impairment, shunt infection, need for shunt revision, need for more than 2 shunt revisions (range 0-8 revisions), symptomatic overdrainage, and older age at the time of the study. CONCLUSIONS The HOQ-Spanish version is useful in the authors' region; the dimension scores found in this study were comparable to those previously reported by referral centers. Future goals should be to prevent shunt complications, routinely get children to reach functional status, and refer patients for adjuvant therapy promptly.

Shunt overdrainage syndrome: review of the literature.

Shunt overdrainage in patients with hydrocephalus still represents a challenge for neurosurgeons, in part due to the lack of agreement or uniformity concerning the entity. Important problems exist relating to the real incidence of the entity, its definition, classification, and the pathophysiological theories behind the various treatment strategies proposed. Recent reports have suggested that the evidence about overdrainage and its consequences is not so robust as presumed. Consequently, the topic requires more detailed examination. In this review, we comment on all the main facets related with shunt overdrainage.