Infantile external hydrocephalus : Epidemiological, radiological, clinical, cognitive, and social aspects

Bakgrunn: Ekstern hydrocefalus («utvendig vannhode») er en tilstand som kan sees hos noen spedbarn med raskt økende hodeomkrets. Radiologisk utredning viser utvidete, væskefylte hulrom på hjernens overflate, spesielt frontalt. Tilstanden har blitt kalt benign (godartet), da de fleste barna tilsynelatende har utviklet seg normalt. Mange barn har dermed heller ikke blitt behandlet. Det foreligger imidlertid begrenset kunnskap om ekstern hydrocephalus, både hyppigheten, utviklingen på lang sikt, og sammenhengen med den liknende tilstanden subduralt hematom (blodansamling på hjernens overflate). Mål: Å finne epidemiologiske data om ekstern hydrocefalus hos spedbarn. Å studere langtidsfølgene av tilstanden, og eventuell effekt av behandling. Å studere patofysiologien bak ekstern hydrocefalus og kronisk subduralt hematom, samt sammenhengen med mistenkt påført hodeskade. Metode: Artikkel 1-4 er en populasjonsbasert studie av alle spedbarn med idiopatisk ekstern hydrocefalus i Helse Vest og Helse Sør-Øst i 10-årsperioden 1994-2003. I artikkel 1 og 3 presenteres epidemiologi, kliniske karakteristika og radiologiske funn. I artikkel 2 og 4 presenteres resultatene av nevropsykologiske tester og livskvalitet hos 8 til 18 år gamle barn/ungdommer som hadde ekstern hydrocefalus som spedbarn. Artikkel 5 er en litteraturstudie av patofysiologien bak ekstern hydrocefalus og kronisk subduralt hematom. Artikkel 6 er en litteraturstudie om tromboserte brovener og sammenhengen med påført hodeskade. Artikkel 7 er en registerstudie av spedbarn med subduralt hematom og mistanke om påført hodeskade, med søkelys på kliniske og radiologiske funn. Resultater: Hyppigheten av idiopatisk ekstern hydrocefalus var 0,4 per 1000 fødte per år. Det var flest gutter (86,4 %). Hovedsymptomet som førte til henvisning var økende hodeomkrets, som oppsto mellom 0 og 7 måneder (snitt 3,4 måneder). Radiologisk utredning viste utvidete sideventrikler hos de fleste barna, og de radiologiske funnene lot til å bestå etter ett års alder. Resultatene av de nevropsykologiske testene ble sammenlignet med normaldata. Utførings-IQ og verbal produksjon var signifikant bedre hos barn med tidligere ekstern hydrocefalus sammenlignet med normaldata, mens oppmerksomhetsspenn, psykomotorisk tempo, eksekutive funksjoner og finmotorikk var dårligere. Barna anga god livskvalitet, mens foreldrene skåret barna til dårligere enn normal livskvalitet på underkategorien ‘skolefunksjon’. Kirurgisk behandlede barn (ventriculoperitoneal shunt) skåret dårligere enn ikke-opererte på to tester for psykomotorisk tempo. Hos noen av pasientene ble det også rapportert ulike kognitive og sosiale problemer. Likheter mellom ekstern hydrocefalus og kronisk subduralt hematom ble studert og diskutert, så som nevroradiologi og væskeegenskaper, og kjønns- og aldersfordeling. En hypotese om perinatalt subduralt hematom som felles utgangspunkt ble presentert. En gjennomgang av relevant litteratur om tromboserte brovener kunne ikke støtte påstanden om at dette radiologiske funnet beviser påført hodeskade hos spedbarn (en påstand som nylig er fremmet i internasjonale studier). Spedbarn med kronisk subduralt hematom og mistanke om påført hodeskade var i hovedsak gutter, var premature, hadde lav dødelighet og var assosiert med mulig forutgående ekstern hydrocefalus. Spedbarn med akutt subduralt hematom, subaraknoidalblødning, eller hypoksisk-iskemisk skade, så ut til å utgjøre andre grupper av barn, muligens med annen etiologi. Konklusjoner: Ekstern hydrocefalus hos spedbarn forekommer hos 0,4 per 1000 fødte per år, om lag halvparten av alle med primær hydrocefalus, og er mest vanlig hos gutter. Selv om det ser ut til å gå bra med de fleste av barna på lang sikt, sliter noen av barna med ulike utviklingsforstyrrelser, og spesielt i forhold til skolefunksjon. Behandling ser ikke ut til å endre utfallet. Mindre blødninger på hjernens overflate er ikke uvanlig i forbindelse med fødselen, og kan muligens være en årsak til både ekstern hydrocefalus og kronisk subduralt hematom noen måneder senere. Disse to tilstandene har påfallende like epidemiologiske trekk, og deres assosiasjon med hverandre må være sentral i tolkningen av subdurale hematomer hos barn der en mistenker påført hodeskade.Background: External hydrocephalus is a condition sometimes seen in infants. It is characterized by an enlarged head or rapidly increasing head circumference. Neuroimaging shows wide subarachnoid spaces, especially overlying the frontal lobes. The condition has traditionally been termed ‘benign’, as most children seem to do well, and symptoms and neuroimaging findings normalize over time. Hence, few infants have been treated for this condition. However, limited knowledge exists on long-term consequences of external hydrocephalus, the possible benefit of treatment, epidemiology, and its connection with the very similar conditions chronic subdural hematoma (SDH) and hygroma (SDHy). Aim: To gain thorough epidemiological data about external hydrocephalus in infants. To explore the long-term consequences of external hydrocephalus, both with and without treatment. To examine the pathophysiology of external hydrocephalus and chronic SDH/SDHy, and their relation to and importance in the investigation of infants with suspected abusive head trauma (AHT). Methods: Papers 1-4 are based on a cohort of infants diagnosed with idiopathic external hydrocephalus in a relatively well-defined population in Southern Norway during the period 1994-2003. Papers 1 and 3 explored the epidemiology, clinical features, and radiology of external hydrocephalus in this cohort. In papers 2 and 4, long-term neurocognitive and psychosocial functioning were evaluated using neuropsychological tests and questionnaires. Paper 5 is a literature survey exploring the pathophysiology behind external hydrocephalus and chronic SDH. Paper 6 is also a review, focusing on the existing knowledge about bridging veins, thrombosis, and its role in AHT diagnostics. Paper 7 is based on a cohort of infants with SDH and alleged AHT. Clinical and neuroimaging findings are explored. Results: The incidence of idiopathic external hydrocephalus was 0.4 per 1000 live births, with a large male preponderance (86.4 %) (paper 1). The main symptom was a large and/or rapidly increasing head circumference, with a mean age at debut of 3.4, range 0-7 months. Neuroimaging showed lateral ventricle enlargement in most cases, with neuroimaging characteristics persisting beyond one year of age (paper 3). The results on neuropsychological tests were compared with the normative mean (paper 2). Performance IQ and verbal fluency in children with prior external hydrocephalus were better than the normative mean, while attention span, psychomotor speed, executive functions, and fine motor functions were poorer. On quality of life, the children scored themselves better than the normative mean, while the parents scored the children poorer on the school subscore. Operated children performed poorer than non-operated ones on two tests of psychomotor speed. For some of the patients, various cognitive and social problems were reported (paper 4). Reviewing the literature, the similarities between external hydrocephalus and chronic SDH were discussed, such as neuroimaging and fluid characteristics, and sex and age distribution. A birth-related perinatal SDH was suggested as a common etiological condition (paper 5). A thorough literature review covering radiological studies, autopsy studies and biomechanical studies could not support the suggestion that neuroimaging signs of thrombosis are markers of bridging vein rupture, and thus AHT (paper 6). Infants with chronic SDH and alleged AHT had a male preponderance and low mortality, and were associated with external hydrocephalus and stretched bridging veins. Infants with acute SDH, subarachnoid hemorrhage, or hypoxic-ischemic injury, seemed to comprise distinct groups (paper 7). Conclusions: Infantile external hydrocephalus occurs in 0.4 of 1000 live births, which is around half of all infants with primary hydrocephalus, and has a marked male preponderance. Although most children with external hydrocephalus seem to do well when growing up, a non-negligible number of patients struggle in various areas, especially related to school functioning. Treatment with a shunting procedure does not seem to improve outcome. As the epidemiological and neuroimaging features of external hydrocephalus and chronic SDH are similar, a common etiology seems plausible. A small SDH during birth could be one possible common cause. External hydrocephalus should also be kept in mind when investigating infants with chronic SDH and alleged AHT. Our results both question the neuroimaging “evidence” of bridging vein rupture, and show that an underlying external hydrocephalus can mimic symptoms and findings of suspected AHT.Doktorgradsavhandlin

Examining perinatal subdural haematoma as an aetiology of extra-axial hygroma and chronic subdural haematoma

Aim: Benign external hydrocephalus (BEH), hygroma and chronic subdural haematoma are extra‐axial fluid collections in infants. MRI studies have shown that almost half of all new‐borns have perinatal subdural blood, generally referred to as subdural haematoma (SDH) or perinatal SDH. Epidemiologically there are striking similarities between chronic SDH and BEH in infants. Methods: Discussion of pathophysiological mechanisms for BEH and chronic SDH, based on existing literature. Results: Perinatal SDH is common, and we hypothesise that this condition in some infants develop into extra‐axial fluid collections, known as hygroma, BEH or chronic subdural haematoma. The mechanism seems to be an intradural bleeding that creates an obstructive layer preventing normal CSF absorption. The site where the bleeding originates from and those areas enveloped in blood from the primary damaged area are prone to later rebleeds, seen as ‘acute on chronic’ haematomas. With steady production of CSF and the blockage, increased intracranial pressure drives the accelerated skull growth seen in many of these children. Conclusion: Perinatal SDH hampers CSF absorption, possibly leading to BEH and chronic SDH, with a high risk of false accusations of abuse. Close monitoring of head circumference could prove vital in detecting children with this condition.publishedVersio

Benign external hydrocephalus: a review, with emphasis on management

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

Examining perinatal subdural haematoma as an aetiology of extra-axial hygroma and chronic subdural haematoma

Aim: Benign external hydrocephalus (BEH), hygroma and chronic subdural haematoma are extra‐axial fluid collections in infants. MRI studies have shown that almost half of all new‐borns have perinatal subdural blood, generally referred to as subdural haematoma (SDH) or perinatal SDH. Epidemiologically there are striking similarities between chronic SDH and BEH in infants. Methods: Discussion of pathophysiological mechanisms for BEH and chronic SDH, based on existing literature. Results: Perinatal SDH is common, and we hypothesise that this condition in some infants develop into extra‐axial fluid collections, known as hygroma, BEH or chronic subdural haematoma. The mechanism seems to be an intradural bleeding that creates an obstructive layer preventing normal CSF absorption. The site where the bleeding originates from and those areas enveloped in blood from the primary damaged area are prone to later rebleeds, seen as ‘acute on chronic’ haematomas. With steady production of CSF and the blockage, increased intracranial pressure drives the accelerated skull growth seen in many of these children. Conclusion: Perinatal SDH hampers CSF absorption, possibly leading to BEH and chronic SDH, with a high risk of false accusations of abuse. Close monitoring of head circumference could prove vital in detecting children with this condition

Quality of life and physician-reported developmental, cognitive, and social problems in children with benign external hydrocephalus—long-term follow-up

Introduction Benign external hydrocephalus (BEH) is characterized by too rapidly increasing head circumference in infants, combined with typical neuroimaging findings. Psychomotor developmental delay is typically seen during the first few years of life; after that, the children’s development assumedly normalizes. However, little is known about the long-term effects of BEH. Methods In this retrospective population-based study, children diagnosed with BEH during the years 1994–2003 in Southern Norway were asked to participate. Included patients (age 8–18 years old) and their parents answered the PedsQL questionnaire. The patient’s family physicians contributed by giving information from medical records, with special emphasis on developmental, cognitive, and social function. Results One hundred seventy-six children were identified with BEH. One hundred three patients and 86 parents completed the PedsQL questionnaire. Supplemental medical information for 142 of the patients was received, mainly from their family physicians. Children and adolescents with BEH score themselves better than the normative mean on health-related quality of life, while the parents score their BEH children within the normative mean, except for the school functioning subgroup, where they score significantly lower. Various developmental, physical, and social problems are reported, like mental retardation, speech problems, epilepsy, motor impairment, psychiatric disorders, and cognitive difficulties. Among these patients, there is a discrepancy in some areas between the child-reported and parent-reported quality of life. Conclusions Children and adolescents who were diagnosed with BEH during infancy generally do well. However, for some patients, there appear to be various developmental, social, and cognitive problems, and they seem to struggle more in school than their healthy peers

Epidemiology of benign external hydrocephalus in Norway - a population-based study

Background: Benign external hydrocephalus is defined as a rapidly increasing head circumference (occipitofrontal circumference) with characteristic radiological findings of increased subarachnoid cerebrospinal fluid spaces on neuroimaging. The incidence of benign external hydrocephalus has not been previously reported, and there is no available information on the ratio of benign external hydrocephalus in the population of hydrocephalic children. Methods: This study is retrospective and population-based study, geographically covering two health regions in the southern half of Norway with a total mean population of 3.34 million in the ten-year study period, constituting approximately 75% of the Norwegian population. Children with a head circumference crossing two percentiles, or greater than the 97.5th percentile, and with typical imaging findings of enlarged frontal subarachnoid spaces with or without enlarged ventricles were included. Children were excluded if they had a history of head trauma, intracranial hemorrhage, central nervous system infection, other known causes of hydrocephalus, or were born preterm defined as birth before 37 weeks of gestation. Results: A total of 176 children fitting the criteria were identified, giving an incidence of 0.4 per 1000 live births. One hundred fifty-two (86.4%) of the patients were male, and mean age at referral was 7.3 months. Increasing head circumference was the main reason for referral in 158 (89.8%) patients and the only finding in 60 (34.1%) patients. Thirty-seven (21%) children had normal ventricles on imaging; the remainder had increased ventricular size. The incidence of pediatric hydrocephalus in Norway is reported to be 0.75 per 1000 live births, thus benign external hydrocephalus accounts for approximately 50% of hydrocephalic conditions in this population. Conclusions: The incidence of benign external hydrocephalus was found to be 0.4 per 1000 live births in this population

Epidemiology of benign external hydrocephalus in Norway - a population-based study

Background: Benign external hydrocephalus is defined as a rapidly increasing head circumference (occipitofrontal circumference) with characteristic radiological findings of increased subarachnoid cerebrospinal fluid spaces on neuroimaging. The incidence of benign external hydrocephalus has not been previously reported, and there is no available information on the ratio of benign external hydrocephalus in the population of hydrocephalic children. Methods: This study is retrospective and population-based study, geographically covering two health regions in the southern half of Norway with a total mean population of 3.34 million in the ten-year study period, constituting approximately 75% of the Norwegian population. Children with a head circumference crossing two percentiles, or greater than the 97.5th percentile, and with typical imaging findings of enlarged frontal subarachnoid spaces with or without enlarged ventricles were included. Children were excluded if they had a history of head trauma, intracranial hemorrhage, central nervous system infection, other known causes of hydrocephalus, or were born preterm defined as birth before 37 weeks of gestation. Results: A total of 176 children fitting the criteria were identified, giving an incidence of 0.4 per 1000 live births. One hundred fifty-two (86.4%) of the patients were male, and mean age at referral was 7.3 months. Increasing head circumference was the main reason for referral in 158 (89.8%) patients and the only finding in 60 (34.1%) patients. Thirty-seven (21%) children had normal ventricles on imaging; the remainder had increased ventricular size. The incidence of pediatric hydrocephalus in Norway is reported to be 0.75 per 1000 live births, thus benign external hydrocephalus accounts for approximately 50% of hydrocephalic conditions in this population. Conclusions: The incidence of benign external hydrocephalus was found to be 0.4 per 1000 live births in this population

Quality of life and physician-reported developmental, cognitive, and social problems in children with benign external hydrocephalus—long-term follow-up

Introduction: Benign external hydrocephalus (BEH) is characterized by too rapidly increasing head circumference in infants, combined with typical neuroimaging findings. Psychomotor developmental delay is typically seen during the first few years of life; after that, the children’s development assumedly normalizes. However, little is known about the long-term effects of BEH. Methods: In this retrospective population-based study, children diagnosed with BEH during the years 1994–2003 in Southern Norway were asked to participate. Included patients (age 8–18 years old) and their parents answered the PedsQL questionnaire. The patient’s family physicians contributed by giving information from medical records, with special emphasis on developmental, cognitive, and social function. Results: One hundred seventy-six children were identified with BEH. One hundred three patients and 86 parents completed the PedsQL questionnaire. Supplemental medical information for 142 of the patients was received, mainly from their family physicians. Children and adolescents with BEH score themselves better than the normative mean on health-related quality of life, while the parents score their BEH children within the normative mean, except for the school functioning subgroup, where they score significantly lower. Various developmental, physical, and social problems are reported, like mental retardation, speech problems, epilepsy, motor impairment, psychiatric disorders, and cognitive difficulties. Among these patients, there is a discrepancy in some areas between the child-reported and parent-reported quality of life. Conclusions: Children and adolescents who were diagnosed with BEH during infancy generally do well. However, for some patients, there appear to be various developmental, social, and cognitive problems, and they seem to struggle more in school than their healthy peers

Thrombosis is not a marker of bridging vein rupture in infants with alleged abusive head trauma

Aim Thrombosis of bridging veins has been suggested to be a marker of bridging vein rupture, and thus AHT, in infants with subdural haematoma. Methods This is a non-systematic review based on Pubmed search, secondary reference tracking and authors’ own article collections. Results Radiological studies asserting that imaging signs of cortical vein thrombosis were indicative of traumatic bridging vein rupture were unreliable as they lacked pathological verification of either thrombosis or rupture, and paid little regard to medical conditions other than trauma. Autopsy attempts at confirmation of ruptured bridging veins as the origin of SDH were fraught with difficulty. Moreover, microscopic anatomy demonstrated alternative non-traumatic sources of a clot in or around bridging veins. Objective pathological observations did not support the hypothesis that a radiological finding of bridging vein thrombosis was the result of traumatic rupture by AHT. No biomechanical models have produced reliable and reproducible data to demonstrate that shaking alone can be a cause of bridging vein rupture. Conclusion There is no conclusive evidence supporting the hypothesis that diagnostic imaging showing thrombosed bridging veins in infants correlates with bridging vein rupture. Hence, there is no literature support for the use of thrombosis as a marker for AHT