Clinical features and outcome in pediatric arteriovenous malformation: institutional multimodality treatment.

PURPOSE: Intracranial arteriovenous-malformation (AVM) is a relatively rare condition in pediatrics, yet is a major cause of spontaneous intracranial hemorrhage with a risk of fatal hemorrhage reported to be between 4 and 29%. Little is known about vessel morphology and optimum treatment modalities including multimodality combination therapy and prognosis in children. METHODS: A retrospective review of all children presenting to our institution from 2006 to 2020 that had an AVM was undertaken. RESULTS: A total of 50 children were identified with median age of 11 (range 1-16) years. The mean follow-up was 7.6 years. Forty-one children presented as an emergency and of those, 40 had hemorrhage identified on initial brain imaging. The average nidus size was 25 mm, drainage was superficial in 51% of cases, and located in eloquent cortex in 56%. The supplemental Spetzler-Martin grading indicated 78% (39/50) were grade 4 and above (moderate to high risk). Primary treatment modalities included embolization in 50% (25) or SRS in 30% (15) and surgery in 20% (10).The AVM was obliterated on follow-up DSA in 66% children. Three children had post-treatment hemorrhage, two related to embolization and one the day following SRS, giving a re-bleed rate of 6%. The GOSE was available for 32 children at long term follow and 94% had a good outcome (GOSE 5-8). Two children died due to acute hemorrhage (4%). CONCLUSION: The majority of children with AVM present with hemorrhage. The rebleed rate during definitive treatment is low at 6% over the study period. The selective use of the 3 modalities of treatment has significantly reduced mortality and severe disability.

Seizure improvement following vagus nerve stimulator (VNS) battery change with cardiac-based seizure detection automatic stimulation (AutoStim): early experience in a regional paediatric unit.

PURPOSE: The recent VNS models (AspireSR® Model 106, SenTiva™ Model 1000 (VNS Therapy®, LivaNova)) include a new function of cardiac-based seizure detection (CBSD) automatic stimulation, known as 'AutoStim'. This algorithm uses tachycardia as a proxy to a seizure, and the battery delivers a closed-loop electrical current in addition to its programmed stimulation. This function leads to further seizure reduction in adults, but this advantage has not been reported in the paediatric population. This study aims to investigate whether battery change with AutoStim leads to further seizure reduction in children. METHODS: This observational study included the first 10 cases of VNS battery change from non-AutoStim to AutoStim function. During the battery change operation, the new VNS was switched on, with the same normal and magnet mode settings as the previous VNS. The AutoStim mode was activated at the same time. Data on seizure burden were collected at 3 time points: (1) before the first VNS insertion, (2) before battery replacement (post-1st VNS) and (3) 12 months post-battery change (post-AutoStim). The net effect of AutoStim, the only changed parameter, was evaluated by comparing the seizure burden prior to and 12 months following battery change in each child. RESULTS: The seizure reduction improved significantly from 60 to 83% following battery change with AutoStim. Categorising the outcome according the McHugh classification, children achieving class I and II outcome (≥ 50% seizure reduction) improved from 70 to 90%. CONCLUSION: This is the first study to demonstrate the additional efficacy of AutoStim in children treated with VNS.

Paediatric spondylodiscitis: a 10-year single institution experience in management and clinical outcomes.

PURPOSE: Discitis in the paediatric population poses diagnostic challenges due to non-specific presenting symptoms and difficulty with expressing pain in non-communicating children. Discitis remains a relatively rare condition in the paediatric population and previous reports are limited to small cohorts. In this article, we report our experience in management of discitis over a 10-year period and review the literature on this topic. METHODS: We retrospectively reviewed cases of paediatric discitis/spondylodiscitis over a 10-year period between 2008 and 2018 managed in our regional paediatric neurosurgery unit. Relevant demographic information, microbiological data, blood investigation profile, antibiotic treatment duration and clinical outcomes were interrogated from clinical notes and electronic databases and further analysed. RESULTS: Overall, 21 cases of paediatric discitis were identified from year 2008 to 2018 with a female to male ratio of 1.3:1. The mean age at presentation was 4.3 years (range 1 to 15 years). Overall, there were 19 cases of lumbosacral/lumbar, 1 thoracic and 1 cervical discitis. The mean duration of follow-up was 20 months (range 6 to 69 months). The most common presenting features were back pain and refusal to walk/sit or weight bear. Erythrocyte sedimentation rate (ESR) was found to be more sensitive than C-reactive protein (CRP) (sensitivity 78% versus 38%) in our cohort. Computer tomography (CT)-guided biopsy was performed in five cases and only one of these was positive (20%). All patients were treated with intravenous antibiotics with resolution of discitis. CONCLUSIONS: Presentation of discitis in children can be non-specific and requires high index of suspicion. CT-guided biopsy in our cohort revealed a low rate of positive cultures. Despite negative blood cultures and CT-guided biopsy results, empirical intravenous antibiotics were effective in treating discitis successfully. In our cohort, low yield of CT-guided biopsy does not support its use on each case and this may be reserved for cases resistant to antimicrobial therapy or concerns regarding other pathology mimicking infection. Better understanding and awareness of this condition and its pathophysiology can lead to timely imaging, diagnosis and treatment.

Paediatric developmental venous anomalies (DVAs): how often do they bleed and where?

INTRODUCTION: Developmental venous anomalies (DVAs) are anomalies of venous drainage and considered a low-flow malformation. Studies evaluating natural history and risk factors for intracranial haemorrhage in the paediatric population are rare. We evaluate clinical and radiological features, risk factors and outcomes of paediatric DVAs. METHODS: A retrospective study was conducted over a 10-year period between 2004 and 2014. Medical records, imaging and prospective databases were reviewed. Three-hundred-and-three radiological studies in total were evaluated. RESULTS: Fifty-two children (20 boys and 32 girls [median age: 6 years] were identified with DVAs. Their age distribution was as follows: 1.9% neonates (< 1 month), 11.5% infants (1 month to 1 year), 30.8% 1-5 years, 30.8% 5-12 years and 25% 12-16 years. The majority (92.3%) presented with asymptomatic DVAs identified incidentally. Overall, anatomical distribution revealed predilection for frontal region (42.3%) with other common sites being posterior fossa (17.3%) and basal ganglia (13.5%). Temporal (11.5%), parietal (9.6%) and occipital (5.8%) were the remainder. Associated cavernous malformations (CMs) were present in 3/52 (5.8%), and no DVAs were associated with aneurysms or arteriovenous malformations (AVMs). Three patients had more than one DVA. There were three deaths unrelated to DVAs over median follow-up of 3.8 years. Four patients (7.7%) suffered DVA-related intracranial haemorrhage presenting with neurological deficits. The ages of the children with DVA-related haemorrhages were 21 days, 2 years and 6 months, 7 years and 1 month and 11 years and 7 months. Left-sided DVA haemorrhages predominated (3/4, 75%). The relative risk of a cerebellar DVA haemorrhage compared to its supratentorial counterpart was 5.35 (OR 6.8, 95% CI 0.8-58). DISCUSSION: DVA-related haemorrhage is sevenfold greater in our paediatric cohort compared to adults and is significantly associated with cerebellar location and cavernous malformations. There were no haemorrhages over a median period of 3.8 years of prospective follow-up.

MEG Assessment of Expressive Language in Children Evaluated for Epilepsy Surgery.

Establishing language dominance is an important step in the presurgical evaluation of patients with refractory epilepsy. In the absence of a universally accepted gold-standard non-invasive method to determine language dominance in the preoperative assessment, a range of tools and methodologies have recently received attention. When applied to pediatric age, many of the proposed methods, such as functional magnetic resonance imaging (fMRI), may present some challenges due to the time-varying effects of epileptogenic lesions and of on-going seizures on maturational phenomena. Magnetoencephalography (MEG) has the advantage of being insensitive to the distortive effects of anatomical lesions on brain microvasculature and to differences in the metabolism or vascularization of the developing brain and also provides a less intimidating recording environment for younger children. In this study we investigated the reliability of lateralized synchronous cortical activation during a verb generation task in a group of 28 children (10 males and 18 females, mean age 12 years) with refractory epilepsy who were evaluated for epilepsy surgery. The verb generation task was associated with significant decreases in beta oscillatory power (13-30 Hz) in frontal and temporal lobes. The MEG data were compared with other available presurgical non-invasive data including cortical stimulation, neuropsychological and fMRI data on language lateralization where available. We found that the lateralization of MEG beta power reduction was concordant with language dominance determined by one or more different assessment methods (i.e. cortical stimulation mapping, neuropsychological, fMRI or post-operative data) in 89% of patients. Our data suggest that qualitative hemispheric differences in task-related changes of spectral power could offer a promising insight into the contribution of dominant and non-dominant hemispheres in language processing and may help to characterize the specialization and lateralization of language processes in children.

Consent in paediatric neurosurgery: adequacy of documentation and parental perspectives.

INTRODUCTION: Consenting paediatric patients for surgical procedures remains inherently unique in that it is underpinned by principles such as parental responsibility, assessment of the child's capacity to consent, and adherence to national/legal guidelines. Quality record keeping is an important objective evidence to demonstrate the highest standards of medical care provided to our patients. The consent form is a crucial medical record encapsulating the attainment of informed consent from a parent/guardian for performing a procedure on their child. We aimed to prospectively evaluate the consenting process in our department to assess adequacy of documentation and parental perspectives. METHODS: A prospective study using qualitative descriptive design was conducted with parents of 50 children requiring neurosurgical procedures over a 3-month period. RESULTS: All patients understood the primary diagnosis and type of surgery. Procedure-specific risks were understood by 98% and 84% could remember the mentioning of general risks of surgery. Only a minority of parents (24%) could recollect that alternative options of management including no treatment were discussed. In cases where relevant, laterality was only documented in 56% of consent forms. All patients felt that an informed decision regarding consent to surgery was made. However, 12% suggested areas where further improvement could be made in the timing of consent and the way information could be better provided. DISCUSSION: Consent is more than a signature on a form. It provides objective evidence of a shared decision-making process between the surgeon, patient, and their parent/guardian. Our initial study highlights multiple areas for improvement.

The utility of Multicentre Epilepsy Lesion Detection (MELD) algorithm in identifying epileptic activity and predicting seizure freedom in MRI lesion-negative paediatric patients.

AIM: Paediatric patients with drug-resistant focal epilepsy (DRFE) who have no clear focal lesion identified on conventional structural magnetic resonance imaging (MRI) are a particularly challenging cohort to treat and form an increasing part of epilepsy surgery programs. A recently developed deep-learning-based MRI lesion detection algorithm, the Multicentre Lesion Detection (MELD) algorithm, has been shown to aid detection of focal cortical dysplasia (FCD). We applied this algorithm retrospectively to a cohort of MRI-negative children with refractory focal epilepsy who underwent stereoelectroencephalography (SEEG) to determine its accuracy in identifying unseen epileptic lesions, seizure onset zones and clinical outcomes. METHODS: We retrospectively applied the MELD algorithm to a consecutive series of MRI-negative patients who underwent SEEG at our tertiary Paediatric Epilepsy Surgery centre. We assessed the extent to which the identified MELD cluster or lesion area corresponded with the clinical seizure hypothesis, the epileptic network, and the positron emission tomography (PET) focal hypometabolic area. In those who underwent resective surgery, we analysed whether the region of MELD abnormality corresponded with the surgical target and to what extent this was associated with seizure freedom. RESULTS: We identified 37 SEEG studies in 28 MRI-negative children in whom we could run the MELD algorithm. Of these, 14 (50 %) children had clusters identified on MELD. Nine (32 %) children had clusters concordant with seizure hypothesis, 6 (21 %) had clusters concordant with PET imaging, and 5 (18 %) children had at least one cluster concordant with SEEG electrode placement. Overall, 4 MELD clusters in 4 separate children correctly predicted either seizure onset zone or irritative zone based on SEEG stimulation data. Sixteen children (57 %) went on to have resective or lesional surgery. Of these, only one patient (4 %) had a MELD cluster which co-localised with the resection cavity and this child had an Engel 1 A outcome. CONCLUSIONS: In our paediatric cohort of MRI-negative patients with drug-resistant focal epilepsy, the MELD algorithm identified abnormal clusters or lesions in half of cases, and identified one radiologically occult focal cortical dysplasia. Machine-learning-based lesion detection is a promising area of research with the potential to improve seizure outcomes in this challenging cohort of radiologically occult FCD cases. However, its application should be approached with caution, especially with regards to its specificity in detecting FCD lesions, and there is still work to be done before it adds to diagnostic utility.

Trampoline-Associated Cranial and Spinal Injuries: A 10-Year Study in a Pediatric Neurosurgery Center.

OBJECTIVE:  There has been an increasing use of trampolines for recreation by children in recent years. Many studies have explored the different types of injuries sustained due to falls from trampolines, but so far none have focused specifically on cranial and spinal injuries. In this study, we describe the pattern of cranial and spinal injuries sustained by pediatric patients that were associated with the use of trampolines and their management in a tertiary pediatric neurosurgery unit over a period of 10 years. METHODS:  This is a retrospective study of all children less than 16 years of age with suspected or confirmed trampoline-associated cranial or spinal injuries, managed by a tertiary pediatric neurosurgery unit from 2010 to 2020. Data collected included the patient's age at the time of injury, gender, neurological deficits, radiological findings, management, and clinical outcome. The data were analyzed to highlight any trends in the pattern of injuries. RESULTS:  A total of 44 patients with a mean age of 8 years (ranging from one year and five months to 15 years and five months) were identified. 52% patients were male. 10 patients (23%) had a reduced Glasgow Coma Scale (GCS) score. In terms of imaging findings, 19 patients (43%) had a radiologically positive head injury, nine (20%) had a craniovertebral junction (CVJ) injury, including the first (C1) and second (C2) cervical vertebrae, and six (14%) had an injury involving other parts of the spine. No patient sustained concurrent head and spinal injuries. Eight (18%) patients had normal radiological findings. Two (5%) had incidental findings on radiology that required subsequent surgery. A total of 31 patients (70%) were managed conservatively. 11 patients (25%) underwent surgery for their trauma, of which seven were cranial. Two further patients underwent surgery for their incidental intracranial diagnoses. One child died from an acute subdural hemorrhage. CONCLUSIONS:  This study is the first to focus on trampoline-associated neurosurgical trauma and report the pattern and severity of cranial and spinal injuries. Younger children (less than five years of age) are more likely to develop a head injury, whereas older children (more than 11 years of age) are more likely to develop a spinal injury following the use of a trampoline. Although uncommon, some injuries are severe and require surgical intervention. Therefore, trampolines should be used prudently with the appropriate safety precautions and measures.

Functional hemispherotomy for epilepsy in the very young.

OBJECTIVE: Epilepsy is one of the most common neurological disorders in children. Among very young children, one-third are resistant to medical treatment, and lack of effective treatment may result in adverse outcomes. Although functional hemispherotomy is an established treatment for epilepsy, its outcome in the very young child has not been widely reported. In this study the authors investigated seizure and developmental results after hemispherotomy in children younger than 3 years. METHODS: The authors reviewed a prospective database of all children younger than 3 years with medically intractable epilepsy who underwent functional hemispherotomy at the authors' institution during the period between 2012 and 2020. Demographic data, epilepsy history, underlying etiology, operative and transfusion details, and seizure and developmental outcomes were analyzed. RESULTS: Twelve patients were included in this study. The mean age (± SD) at seizure onset was 3 ± 2.6 months and at surgery was 1.3 ± 0.77 years, with a mean follow-up of 4 years. Diagnoses included hemimegalencephaly (n = 5), hemidysplasia (n = 2), hypoxic/hemorrhagic (n = 2), traumatic (n = 1), Sturge-Weber syndrome (n = 1), and mild hemispheric structural abnormality with EEG/PET correlates (n = 1). Eleven patients achieved an Engel class I outcome, and 1 patient achieved Engel class IV at last follow-up. No deaths, infections, cerebrovascular events, or unexpected long-term neurological deficits were recorded. All children progressed neurodevelopmentally following surgery, but their developmental levels remained behind their chronological age, with an overall mean composite Vineland Adaptive Behavior Scale score of 58 (normal: 86-114, low: < 70). One patient required insertion of a subdural peritoneal shunt, 1 patient required dural repair for a CSF fluid leak, and 1 patient required aspiration of a pseudomeningocele. In 2 patients, both of whom weighed less than 5.7 kg, the first operation was incomplete due to blood loss. CONCLUSIONS: Hemispherotomy in children younger than 3 years offers excellent seizure control and an acceptable risk-to-benefit ratio in well-selected patients. Families of children weighing less than 6 kg should be counseled regarding the possibility of staged surgery. Postoperatively, children continue to make appropriate, despite delayed, developmental progress.

An unusual complication following translabyrinthine resection of an acoustic neuroma.

We report the case of a 58-year old man who presented with a 4 cm right acoustic neuroma. He underwent a translabyrinthine resection. Two years later he presented with multiple strokes and progressive generalised deterioration. A cerebral angiogram demonstrated an extensive right side cerebellar dural arteriovenous fistula with retrograde flow causing corticovenous reflux. The fistula was treated successfully endovascularly. There is only one published report of a dural arteriovenous fistula occurring following acoustic neuromas surgery. The pathogenesis and management of this unusual complication is discussed.

MEG detection of high frequency oscillations and intracranial-EEG validation in pediatric epilepsy surgery.

OBJECTIVE: To assess the feasibility of automatically detecting high frequency oscillations (HFOs) in magnetoencephalography (MEG) recordings in a group of ten paediatric epilepsy surgery patients who had undergone intracranial electroencephalography (iEEG). METHODS: A beamforming source-analysis method was used to construct virtual sensors and an automatic algorithm was applied to detect HFOs (80-250 Hz). We evaluated the concordance of MEG findings with the sources of iEEG HFOs, the clinically defined seizure onset zone (SOZ), the location of resected brain structures, and with post-operative outcome. RESULTS: In 8/9 patients there was good concordance between the sources of MEG HFOs and iEEG HFOs and the SOZ. Significantly more HFOs were detected in iEEG relative to MEG t(71) = 2.85, p < .05. There was good concordance between sources of MEG HFOs and the resected area in patients with good and poor outcome, however HFOs were also detected outside of the resected area in patients with poor outcome. CONCLUSION: Our findings demonstrate the feasibility of automatically detecting HFOs non-invasively in MEG recordings in paediatric patients, and confirm compatibility of results with invasive recordings. SIGNIFICANCE: This approach provides support for the non-invasive detection of HFOs to aid surgical planning and potentially reduce the need for invasive monitoring, which is pertinent to paediatric patients.

Pediatric stereo-electroencephalography: effects of robot assistance and other variables on seizure outcome and complications.

OBJECTIVE: The safety of stereo-electroencephalography (SEEG) has been investigated; however, most studies have not differentiated pediatric and adult populations, which have different anatomy and physiology. The purpose of this study was to assess SEEG safety in the pediatric setting, focusing on surgical complications and the identification of patient and surgical risk factors, if any. The authors also aimed to determine whether robot assistance in SEEG was associated with a change in practice, surgical parameters, and clinical outcomes. METHODS: The authors retrospectively studied all SEEG cases performed in their department from December 2014 to March 2020. They analyzed both demographic and surgical variables and noted the types of surgery-related complications and their management. They also studied the clinical outcomes of a subset of the patients in relation to robot-assisted and non-robot-assisted SEEG. RESULTS: Sixty-three children had undergone 64 SEEG procedures. Girls were on average 3 years younger than the boys (mean age 11.1 vs 14.1 years, p < 0.01). The overall complication rate was 6.3%, and the complication rate for patients with left-sided electrodes was higher than that for patients with right-sided electrodes (11.1% vs 3.3%), although the difference between the two groups was not statistically significant. The duration of recording was positively correlated to the number of implanted electrodes (r = 0.296, p < 0.05). Robot assistance was associated with a higher number of implanted electrodes (mean 12.6 vs 7.6 electrodes, p < 0.0001). Robot-assisted implantations were more accurate, with a mean error of 1.51 mm at the target compared to 2.98 mm in nonrobot implantations (p < 0.001). Clinical outcomes were assessed in the first 32 patients treated (16 in the nonrobot group and 16 in the robot group), 23 of whom proceeded to further resective surgery. The children who had undergone robot-assisted SEEG had better eventual seizure control following subsequent epilepsy surgery. Of the children who had undergone resective epilepsy surgery, 42% (5/12) in the nonrobot group and 82% (9/11) in the robot group obtained an Engel class IA outcome at 1 year (χ2 = 3.885, p = 0.049). Based on Kaplan-Meier survival analysis, the robot group had a higher seizure-free rate than the nonrobot group at 30 months postoperation (7/11 vs 2/12, p = 0.063). Two complications, whose causes were attributed to the implantation and head-bandaging steps, required surgical intervention. All complications were either transient or reversible. CONCLUSIONS: This is the largest single-center, exclusively pediatric SEEG series that includes robot assistance so far. SEEG complications are uncommon and usually transient or treatable. Robot assistance enabled implantation of more electrodes and improved epilepsy surgery outcomes, as compared to those in the non-robot-assisted cases.

Transtemporal approach to hypothalamic hamartomas in children: report of 3 cases.

The surgical approach to hypothalamic hamartomas (HHs) associated with medically refractory epilepsy is challenging because of these lesions' deep midline or paramedian location. Whether the aim is resection or disconnection, the surgical corridor dictates how complete a procedure can be achieved. Here, the authors report a transtemporal approach suitable for Delalande type I, inferior extraventricular component of type III, and type IV lesions. This approach provides optimal visualization of the plane between the hamartoma and the hypothalamus with no manipulation to the pituitary stalk and brainstem, allowing for extensive disconnection while minimizing injury to adjacent neurovascular structures.Through a 1-cm corticectomy in the middle temporal gyrus, a surgical tract is developed under neuronavigational guidance toward the plane of intended disconnection. On reaching the mesial temporal pia-arachnoid margin, it is opened, providing direct visualization of the hamartoma, which is then disconnected or resected as indicated. Critical neurovascular structures are generally not exposed through this approach and are preserved if encountered.Three patients (mean age 4.9 years) with intractable epilepsy were treated using this technique as part of the national Children's Epilepsy Surgery Service. Following resection, the patient in case 1 (Delalande type I) is seizure free off medication at 3 years' follow-up (Engel class IA). The patient in case 2 (Delalande type III) initially underwent partial disconnection through a transcallosal interforniceal approach and at first had significant seizure improvement before the seizures worsened in frequency and type. Complete disconnection of the residual lesion was achieved using the transtemporal approach, rendering this patient seizure free off medication at 14 months postsurgery (Engel class IA). The patient in case 3 (Delalande type IV) underwent incomplete disconnection with a substantial reduction in seizure frequency at 3 years' follow-up (Engel class IIIC). There were no surgical complications in any of the cases.The transtemporal approach is a safe and effective alternative to more conventional surgical approaches in managing HHs with intractable epilepsy.

Mapping language networks and their association with verbal abilities in paediatric epilepsy using MEG and graph analysis.

Recent theoretical models of language have emphasised the importance of integration within distributed networks during language processing. This is particularly relevant to young patients with epilepsy, as the topology of the functional network and its dynamics may be altered by the disease, resulting in reorganisation of functional language networks. Thus, understanding connectivity within the language network in patients with epilepsy could provide valuable insights into healthy and pathological brain function, particularly when combined with clinical correlates. The objective of this study was to investigate interactions within the language network in a paediatric population of epilepsy patients using measures of MEG phase synchronisation and graph-theoretical analysis, and to examine their association with language abilities. Task dependent increases in connectivity were observed in fronto-temporal networks during verb generation across a group of 22 paediatric patients (9 males and 13 females; mean age 14 years). Differences in network connectivity were observed between patients with typical and atypical language representation and between patients with good and poor language abilities. In addition, node centrality in left frontal and temporal regions was significantly associated with language abilities, where patients with good language abilities had significantly higher node centrality within inferior frontal and superior temporal regions of the left hemisphere, compared to patients with poor language abilities. Our study is one of the first to apply task-based measures of MEG network synchronisation in paediatric epilepsy, and we propose that these measures of functional connectivity and node centrality could be used as tools to identify critical regions of the language network prior to epilepsy surgery.

Influence of shunt type on ventricular volume changes in children with hydrocephalus.

OBJECT: The goal of this study was twofold: to investigate the change in ventricular volume in children with hydrocephalus in response to shunt placement and to assess the effects of two different valve types (Medium Pressure [MP] cylindrical valve and Delta [model 1.5] valve). METHODS: Ventricular volume was measured using segmentation techniques on computerized tomography scans and magnetic resonance images obtained in 40 children with hydrocephalus who ranged in age from 4 days to 16 years. Imaging was performed preoperatively and at 5 days and 3, 6, and 12 months postoperatively. The results were compared with measurements obtained in 71 healthy children ranging in age from 1 month to 15 years. Each ventricular volume that was measured was divided by the corresponding sex and age-related mean normal volume to calculate the "x normal" ventricular volume, indicating how many times larger than normal the ventricle was. The mean preoperative ventricular volume was 232 cm3 (range 50-992 cm3). The mean postoperative volumes were 147, 102, 68, and 61 cm3 at 5 days and at 3, 6, and 12 months posttreatment, respectively. The mean preoperative x normal ventricular volume was 14.5 (range 2.2-141.7), and the mean postoperative x normal volumes were 7.9, 5.6, 3.5, and 2.9 at 5 days and 3, 6, and 12 months postimplantation, respectively. The rate of volume reduction was consistently higher in patients who received the MP valve in comparison with those who received the Delta valve, both for new shunt insertions and for shunt revisions. The difference between the two valve groups did not reach statistical significance. Two patients in whom ventricular volumes increased during the study period experienced shunt obstruction at a later time. CONCLUSIONS: Preoperative ventricular volume in children with hydrocephalus can be up to 14 times greater than normal. In response to shunt placement, the ventricular volume continues to fall during the first 6 months after operation. The effect is more profound in children who receive the MP valve than in those who receive the Delta valve, although in this study the authors did not demonstrate statistical significance in the difference between the two valves. Nevertheless, this may indicate that the MP valve produces overdrainage in comparison with the Delta valve, even within the first few months after insertion. There is some indication that sequential ventricular volume measurement may be used to identify impending shunt failure.

Hindbrain-hernia-related syringomyelia without syringobulbia, complicated by permanent nocturnal central hypoventilation requiring non-invasive ventilation.

INTRODUCTION: In the absence of syringobulbia, hindbrain hernia does not commonly cause permanent respiratory complications. We present two patients who developed permanent central nocturnal hypoventilation following acute deterioration of hindbrain-hernia-related syringomyelia despite successful surgery. PATIENTS: Two children (one boy and one girl, aged 7 and 13 years, respectively) presented with acute neurological deterioration. The boy presented with a 6-week history of progressive tiredness and weakness and a short history of respiratory depression. The girl presented with a 2-year history of left hemiparesis and a short history of left hemiplegia and respiratory depression. On magnetic resonance scan, both had hindbrain hernia, hydrocephalus and cervical syringomyelia. Following cranio-vertebral decompression and, later, a ventriculoperitoneal shunt, the syringomyelia remained well controlled in both patients. In contrast, their respiratory depression improved minimally. Repeated multichannel respiratory monitoring revealed a persistently slow sleeping respiratory rate, with nocturnal hypercapnia and hypoxemia, managed successfully by night-time non-invasive ventilation. Neither the boy nor the girl, after 7 and 4 years, respectively, has developed any complications of nocturnal hypoventilation. When awake, both breathe normally. RESULT: Both children appear to have suffered a permanent impairment of respiratory control, resulting in nocturnal hypoventilation. This is usually seen with brain stem lesions and is unexpected when syringomyelia does not extend above C2, in the absence of syringobulbia. DISCUSSION: Central nocturnal hypoventilation is postulated to be due to permanent damage of central brain stem pathways controlling the respiratory muscles, due to local pressure at the cranio-cervical junction associated with acute deterioration of the hindbrain herniation. CONCLUSION: Sudden deterioration of hindbrain hernia and cervical syringomyelia can rarely impair the central mechanisms of respiratory control, with long-term implications on quality of life.

Risk factors for developing epilepsy after craniotomy in children.

INTRODUCTION: We performed a retrospective analysis of children undergoing supratentorial craniotomy, attempting to identify possible risk factors for postoperative epilepsy and the need for prophylactic anticonvulsant therapy. MATERIALS AND METHODS: We analysed 107 consecutive patients (55% males) who had supratentorial craniotomy for a variety of diagnoses (tumours, trauma, infection, vascular malformations and others) during 1995-1999. Mean age at operation was 89 months (range: 1-180 months). Patients who presented with epilepsy were excluded. Postoperative epilepsy was considered present if patients required systematic pharmacological treatment, at a minimum follow-up of 6 months. Linear regression was used to analyse the effect of sex, anticonvulsant prophylaxis, duration of operation, closure of dura, postoperative infection, the diagnosis, anatomical region of brain affected, operation type (craniotomy/craniectomy) and the need for brain resection. RESULTS: Prophylactic anticonvulsants were given to 52% of the patients; 97% had craniotomy; in five patients, the dura was left open; in 33%, some kind of brain tissue resection had been performed; two patients (1.8%) developed postoperative infection; one patient died. Only 13 patients (12%) developed postoperative epilepsy. The only two factors with statistical significance were female sex (p=0.045) and the absence of dural closure (p=0.001). All other factors were not significant (p>0.258). CONCLUSIONS: Postoperative epilepsy after supratentorial craniotomy is uncommon in children, incidence being 12%. The administration of prophylactic anticonvulsants does not appear to influence the risk of epilepsy. Surprisingly, females have statistically higher risk. Lack of dural closure has higher risk of epilepsy, but this may reflect the type of pathology.