Low-grade ependymoma with late metastasis: autopsy case study and literature review.

INTRODUCTION: Ependymoma metastasis occurs usually along with local recurrence within 7 years after the initial diagnosis. Later spinal metastasis without local recurrence after the surgical resection has been rarely reported in patients with low-grade ependymomas but not with high-grade ependymomas. Here, we present a case with autopsy revealing late extensive supratentorial metastasis of a fourth ventricle classic WHO grade II ependymoma with no local recurrence or spinal metastasis. METHODS: A 4-year-old boy underwent a gross total resection (GTR) of the fourth ventricle ependymoma and postoperative radiation therapy. Follow-up MRI showed no recurrence for the next 7 years, but a half year later, extra-axial tumors in the left cerebellopontine angle and right frontal lobe were observed. GTR of the left cerebellopontine angle ependymoma was performed, followed by additional radiation therapy. RESULTS: He was stable for the following 2 years before MRI revealed growth of the right frontal tumor and new lesions. GTR of the right frontal tumor demonstrated similar pathologic features of ependymoma. Despite chemotherapy, follow-up MRIs exhibited increasing numbers and sizes of supratentorial tumors but no infratentorial or spinal tumors. He died 15 years after the initial diagnosis. Postmortem brain examination confirmed the supratentorial subarachnoid dissemination with multifocal metastases of classic ependymomas but no recurrence at the infratentorial sites. CONCLUSION: Our case study and literature review suggest that low-grade ependymomas under the current WHO classification have the risk of late metastasis. Therefore, long-term follow-up of the whole neuroaxis is more important for the patients with low-grade ependymomas even in the absence of local recurrence.

Interpretation of surgical neuromonitoring data in Canada: a survey of practising surgeons.

Intraoperative neuromonitoring is a specialized skill set performed in the operating room to reduce the risk of neurologic injury. There appears to be a shortage of qualified personnel and a lack of Canadian guidelines on the performance of the task. We distributed a web-based survey on the attitude of the surgeons to the interpretation of intraoperative neuromonitoring data among surgeons who use the technique. At present, most of the interpretation is performed by either technologists or by the surgeons themselves. Most surgeons would prefer professional oversight from a neurologist or neurophysiologist at the doctoral level. There is a lack of personnel in Canada with the appropriate training and expertise to interpret intraoperative neuromonitoring data.

Split Notochord Syndrome with Spinal Column Duplication and Spinal Cord Lipoma: A Case Report.

BACKGROUND AND IMPORTANCE: Split notochord syndrome (SNS) is an exceedingly rare type of spinal dysraphism. SNS is sometimes associated with other congenital dysraphic defects but, as in our case, the association with spinal cord lipoma, tethered cord, and spinal deformity in the form of spinal column duplication would be exceedingly rare. Herein, the authors report a three-year-old child presented with SNS associated with complex spinal deformity and other associated congenital anomalies. The patient underwent microsurgical release of the tethering element with excellent short- and long-term outcomes. CLINICAL PRESENTATION: A male newborn with healthy nonconsanguineous parents was born with multiple gastrointestinal and genitourinary anomalies, and duplicated vertebral columns at the lumbosacral area consistent with split notochord syndrome. The patient was initially managed for the gastrointestinal and genitourinary anomalies. As there was no obvious neurological deficit initially, the neurosurgical intervention was postponed till the child reached 30 months of age, when he underwent uneventful release of both spinal cords at their spit point. CONCLUSIONS: SNS is an exceedingly rare developmental anomaly that is usually associated with varying degrees of complex congenital dysraphic defects. Early clinical diagnosis, understanding of the pathophysiology of spinal cord tethering, and microsurgical cord untethering are the important steps in optimal management.

Magnetic resonance imaging analysis of human skull diploic venous anatomy.

BACKGROUND: The skull diploic venous space (DVS) represents a potential route for cerebrospinal fluid (CSF) diversion and absorption in the treatment of hydrocephalus. The goal of this study was to carry out a detailed characterization of the drainage pattern of the DVS of the skull using high-resolution MRI, especially the diploic veins draining to the lacunae laterales (LLs) since the LLs constitute an important channel for the CSF to access the superior sagittal sinus and subsequently the systemic circulation. The objective was to identify those skull regions optimally suited for an intraosseous CSF diversion system. METHODS: High-resolution, T1-weighted MRI scans from 20 adult and 16 pediatric subjects were selected for analysis. Skulls were divided into four regions, that is, frontal, parietal, temporal, and occipital. On each scan, a trained observer counted all diploic veins in every skull region. Each diploic vein was also followed to determine its final drainage pathway (i.e., dural venous sinus, dural vein, LL, or indeterminate). RESULTS: In the adult age group, the frontal and occipital skull regions showed the highest number of diploic veins. However, the highest number of draining diploic veins connecting to the lacunae lateralis was found in the frontal and parietal skull region, just anterior and just posterior to the coronal suture. In the pediatric age group, the parietal skull region, just posterior to the coronal suture, showed the highest overall number of diploic veins and also the highest number of draining diploic veins connecting to the LL. CONCLUSION: This study suggested that diploic venous density across the skull varies with age, with more parietal diploic veins in the pediatric age range, and more occipital and frontal diploic veins in adults. If the DVS is ultimately used for CSF diversion, our anatomical data point to optimal sites for the insertion of specially designed intraosseous infusion devices for the treatment of hydrocephalus. Likely the optimal sites for CSF diversion would be the parietal region just posterior to the coronal suture in children, and in adults, frontal and/or parietal just anterior or just posterior to the coronal suture.

Epilepsy surgery in the first 3 years of life: a Canadian survey.

OBJECTIVE: To determine the clinical characteristics, surgical challenges, and outcome in children younger than 3 years of age undergoing epilepsy surgery in Canada. METHODS: Retrospective data on patients younger than age 3 years who underwent epilepsy surgery at multiple centers across Canada from January 1987 to September 2005 were collected and analyzed. RESULTS: There were 116 patients from eight centers. Seizure onset was in the first year of life in 82%, and mean age at first surgery was 15.8 months (1-35 months). Second surgeries were done in 27 patients, and a third surgery in 6. Etiologies were malformations of cortical development (57), tumor (22), Sturge-Weber syndrome (19), infarct (8), and other (10). Surgeries comprised 40 hemispheric operations, 33 cortical resections, 35 lesionectomies, 7 temporal lobectomies, and one callosotomy. There was one surgical mortality. The most common surgical complications (151 operations in 116 patients) were infection (17) and aseptic meningitis in 13. Of 107 patients with seizure outcome assessed more than one year postoperatively, 72 (67.3%) were seizure free (Engel I), 15(14%) had >90% improvement (Engel II), 12 had >50% improvement (Engel III), and 8 did not benefit from surgery (Engel IV). Development improved in 55.3% after surgery. CONCLUSION: Epilepsy surgery in children younger than 3 years of age is relatively safe and is effective in controlling seizures. Very young age is not a contraindication to surgery in children with refractory epilepsy, and early surgery may impact development positively.

Diploic venous anatomy studied in-vivo by MRI.

Calvarial diploic venous anatomy has been studied post-mortem, but few studies have addressed these venous structures in-vivo. Previous work in our laboratory has shown that intraosseous infusion through the skull diploic space near the diploic veins in animals and humans does access the superior sagittal sinus and the systemic venous system. We developed a volumetric method of imaging the diploic veins in-vivo using MRI, intravenous gadolinium, and digital subtraction to provide for three-dimensional depiction and exact localization of these veins. We hypothesized that this technique would allow for an assessment of the probability of existence, distribution, and concentration of diploic veins in the skull. We scanned 31 neurosurgical patients, and were able to create 3D diploic venous maps in 74% of them. These maps were processed using Adobe Photoshop CS2. Mathworks MatLab 6.5, once customized, counted the number of pixels occupied by the diploic veins in the processed image. The probability of veins was highest in the occipital regions (100%). The inferior occipital (4.1%) and posterior parietal (4.1%) regions had the highest concentrations of diploic veins. Digital subtraction venography using a volumetric MRI sequence can demonstrate the diploic veins in-vivo. The inferior occipital region may be the best area for an intraosseous infusion device because it has the greatest likelihood of containing a vein and also has the highest concentration of veins.

Long-term 3D CT follow-up after endoscopic sagittal craniosynostosis repair.

OBJECTIVE: Surgical treatment of sagittal synostosis involves various surgical modalities. Long-term follow-up issues include increased intracranial pressure, secondary sutural fusion, incomplete reossification, and suboptimal cosmetic appearance. The authors' objective in this study was to review their long-term endoscopic surgical results in children with sagittal synostosis using 3D CT. METHODS: The authors reviewed the long-term results of their first 38 patients who underwent endoscopic sagittal synostosis repair at age 16 weeks or younger. A standard vertex craniectomy with biparietal wedges was done in each case. After surgery, the children were fitted with a helmet, which they wore until 8 months of age. Patients were followed up for 5 years or longer, at which point a 3D CT scan was obtained. The authors examined data on the cranial index, area of bony defect, presence or absence of secondary sutural fusion, neosuture formation, and scalloping of the inner table of the skull. RESULTS: Thirty-two of 38 children met inclusion criteria. There was a small but significant recession of the cranial index after the completion of helmeting (from 0.772 after completion of helmeting to 0.755 at 5 years). Of 32 children, 14 had a bony defect area > 4 cm2. Three children had secondary sutural fusion (two unilateral coronal, one bicoronal). Ten of 32 patients had partial neosuture formation. CONCLUSIONS: The authors report their experience with 32 of their first 38 children who underwent endoscopic sagittal synostosis repair at 16 weeks of age or younger. With a minimum duration of 5 years, this is the longest clinicoradiological follow-up utilizing 3D CT to date in children with sagittal synostosis treated with endoscopic surgery. The authors report detailed measurements of bony loss, adjacent sutural fusion, and neosuture formation.

Intraoperative acquisition of DTI in cranial neurosurgery: readout-segmented DTI versus standard single-shot DTI.

OBJECTIVE: Diffusion tensor imaging (DTI) tractography is commonly used in neurosurgical practice but is largely limited to the preoperative setting. This is due primarily to image degradation caused by susceptibility artifact when conventional single-shot (SS) echo-planar imaging (EPI) DTI (SS-DTI) is acquired for open cranial, surgical position intraoperative DTI (iDTI). Readout-segmented (RS) EPI DTI (RS-DTI) has been reported to reduce such artifact but has not yet been evaluated in the intraoperative MRI (iMRI) environment. The authors evaluated the performance of RS versus SS EPI for DTI of the human brain in the iMRI setting. METHODS: Pre- and intraoperative 3-T 3D T1-weighted and 2D multislice RS-iDTI (called RESOLVE [readout segmentation of long variable echo-trains] on the Siemens platform) and SS-iDTI images were acquired in 22 adult patients undergoing intraaxial iMRI resections for suspected low-grade glioma (14; 64%), high-grade glioma (7; 32%), or focal cortical dysplasia. Regional susceptibility artifact, anatomical deviation relative to T1-weighted imaging, and tractographic output for surgically relevant tracts were compared between iDTI sequences as well as the intraoperative tract shifts from preoperative DTI. RESULTS: RS-iDTI resulted in qualitatively less regional susceptibility artifact (resection cavity, orbitofrontal and anterior temporal cortices) and mean anatomical deviation in regions most prone to susceptibility artifact (RS-iDTI 2.7 ± 0.2 vs SS-iDTI 7.5 ± 0.4 mm) compared to SS-iDTI. Although tract reconstruction success did not significantly differ by DTI method, susceptibility artifact-related tractography failure (of at least 1 surgically relevant tract) occurred for SS-iDTI in 8/22 (36%) patients, and in 5 of these 8 patients RS-iDTI permitted successful reconstruction. Among cases with successful tractography for both sequences, maximal intersequence differences were substantial (mean 9.5 ± 5.7 mm, range -27.1 to 18.7 mm). CONCLUSIONS: RS EPI enables higher quality and more accurate DTI for surgically relevant tractography of major white matter tracts in intraoperative, open cranium neurosurgical applications at 3 T.

Access to cerebrospinal fluid absorption sites by infusion into vascular channels of the skull diplö.

OBJECT: The purpose of this human cadaver study was to determine whether or not an intraosseous skull infusion would access the superior sagittal sinus (SSS) via intradural venous channels. The diploic space of the skull bone contains a sinusoidal vascular network that communicates with the underlying dura mater. Diploic veins in the parasagittal area connect with endothelium-lined intradural channels in the subjacent dura and ultimately with the dural venous sinuses. A significant proportion of cerebrospinal fluid (CSF) absorption is thought to occur via arachnoid granulations in the region of the SSS and especially along the parasagittal dura where arachnoid granulations are surrounded by intradural venous channels (lateral lacunae). The CSF is likely to be conducted from the subarachnoid space into the venous system via the fine intradural channels making up the lateral lacunae. METHODS: Infusion of vinyl acetate casting material into the diploic space of the human cadaveric skull resulted in complete filling of the lateral lacunae and SSS. Corrosion casting techniques and examination under magnification were used to characterize the anatomical connections between diploic spaces and dural venous sinuses. RESULTS: Corrosion casting, performed on five formalin-fixed cadavers, clearly showed the anatomical connections between the diploic infusion site and the venous sinuses in the underlying parasagittal dura where some of the CSF is thought to be absorbed. CONCLUSIONS: The diploic vascular channels of the human skull may represent an indirect pathway into the dural venous sinuses. Intraosseous skull infusion may represent another possible strategy for diversion of CSF into the vascular system in the treatment of hydrocephalus.

Intraosseous infusion into the skull: potential application for the management of hydrocephalus.

OBJECT: Hydrocephalus results from abnormal cerebrospinal fluid (CSF) volumes or flow patterns. The absorption of CSF is determined largely by pressures within veins and venous sinuses in the head and adjacent to the spine. Most surgical solutions for hydrocephalus involve diversion of excess CSF into alternative absorption sites, and most of these solutions are still suboptimal. The focus of this work has been to recreate more normal CSF absorption into the dural venous sinuses without having to directly access the superior sagittal sinus (SSS). METHODS: Intraosseous skull infusion for the purpose of accessing the SSS and the systemic venous system was tested by experimental skull infusions of tracer fluids into living large animals (14 adult pigs). Compared with control injections into an ear vein, infusions into the skull through specially designed infusion devices had similar systemic absorption characteristics. This suggested that intraosseous skull infusion in a living large animal was successful in gaining access to the SSS and systemic venous system. CONCLUSIONS: This study constitutes the first demonstration of the success of intraosseous skull infusion in gaining rapid access to the systemic venous system and it thus opens the possibility of using this strategy for diversion of CSF back into the intracranial venous system for the treatment of hydrocephalus.

Discontinuation of antiepileptic drugs after pediatric epilepsy surgery.

In children with medically intractable seizures, epilepsy surgery is now a widely accepted option. Successful discontinuation of antiepileptic drugs after epilepsy surgery has been reported in adults, but rarely in children. Surgical outcome and need for antiepileptic drugs after temporal and extratemporal lobe resection were retrospectively reviewed for 80 pediatric patients from the Comprehensive Epilepsy Program at the University of Alberta. For 1 year after surgery, children were maintained on at least one antiepileptic drug. Antiepileptic drug discontinuation was attempted in all patients with a nonepileptic electroencephalogram after 1 year seizure-free. Less than half of the patients (44%) eventually relapsed without antiepileptic drugs. Of the 40 patients in the temporal lobe group, 13 (32%) relapsed without antiepileptic drugs, as did 22 of the 40 extratemporal lobe resection patients (55%). Success rates for antiepileptic drug discontinuation after surgery were higher in the temporal lobe than in the extratemporal lobe group. Long-term antiepileptic drugs are not necessary in all cases, and for many children medication can be withdrawn after epilepsy surgery.

The prevalence of intracranial complications in pediatric frontal sinusitis.

OBJECTIVE: Intracranial extension of infection represents a serious complication of sinusitis but with no clearly documented prevalence. The frontal sinus with its unique anatomical characteristics, has been singled out as a catalyst for intracranial spread, but without solid evidence. Our objective was to determine the prevalence of intracranial complications in pediatric acute frontal sinusitis and to test the claimed association. METHODS: A retrospective chart review of all children (

Further characterization of traumatic subdural collections of infancy. Report of five cases.

Bilateral convexity and interhemispheric subdural hematomas are common neuroimaging patterns seen in infants who have sustained nonaccidental head injuries (NAHIs). These collections often appear aschronic or acute-on-chronic on computerized tomography (CT) studies. To determine the nature of these extraaxial fluid collections and their relationship to cerebrospinal fluid (CSF) dynamics, the authors studied five infants with suspected NAHI in whom symptomatic bilateral mixed- or low-density subdural collections were revealed on imaging studies; the patients underwent burr hole evacuation of the hematoma and external drainage. Once decompression was achieved, radiotracer was injected into the lumbar subarachnoid space, and the subdural drainage system was monitored for appearance of the isotope. In all five cases, the radiotracer moved rapidly from the lumbar subarachnoid space into the convexity subdural space and then into the external drainage system. This indicated the possibility that some of these mixed-density subdural collections were acute blood mixed with CSF rather than acute-on-chronic collections arising from rebleeding subdural membranes. The authors propose that, during infancy, tears in the loosely adherent arachnoid envelope at the main arachnoid granulation site along the superior sagittal sinus may result in a considerable amount of CSF mixing with acute blood in the subdural space, creating a hematohygroma.

Extratemporal resection for childhood epilepsy.

There have been relatively few studies reporting the safety, efficacy, and outcome in children undergoing extratemporal resection for epilepsy. We reviewed the pediatric cases of extratemporal resection for intractable epilepsy performed by the Comprehensive Epilepsy Program at the University of Alberta Hospitals between 1988-1998. Thirty-five patients were studied, 14 male and 21 female. The age at operation ranged from 6 months to 16 years. The operations included frontal excisions (12), parietal (8), occipital (4), hemispherectomies or multilobar resections (10), and one removal of a hypothalamic hamartoma. The pathology at surgery included patients with focal cortical dysplasia (8), brain tumors (6), neurocutaneous syndrome (7), Rasmussen's encephalitis (2), porencephalic cysts (4), hypothalamic hamartoma (1), and nonspecific gliosis (6). Twenty-four of 35 patients (68.5%) had an Engel Class I outcome after surgery and an additional six patients (11%) had a significant decrease in seizure frequency (Engel Class III). Complications were observed in two patients (5%) and there were no deaths. Extratemporal resection is a safe and effective treatment for children with intractable epilepsy. Overall, 68% of patients were seizure-free after surgery, although outcome may be dependent on site and pathology. A wide range of developmental pathology was observed including focal cortical dysplasia, brain tumors, and lesions with neurocutaneous syndromes. Many families reported improvement in behavior and psychosocial function after surgery.

Pediatric epilepsy surgery at the University of Alberta: 1988-2000.

Epilepsy surgery is considered a treatment option for patients with intractable seizures. Relatively few studies of efficacy, safety, and long-term outcome are available for the pediatric age group. This study describes a 12-year experience with pediatric epilepsy surgery at the University of Alberta. Records of pediatric epilepsy surgery patients admitted to the Comprehensive Epilepsy Program at the University of Alberta between 1988 and 2000 were reviewed. All patients received preoperative and postoperative clinical evaluation, seizure charts, testing of drug levels, electroencephalogram, computed tomography/magnetic resonance imaging, neuropsychologic testing, and long-term video electroencephalogram monitoring. The patients were reassessed after surgery at 6 weeks, 6 months, and 1 year and then yearly. The duration of follow-up was 1 year to 12 years. Forty-two patients underwent temporal lobectomies; 35, extratemporal resection. The age at surgery ranged from 6 months to 16 years. Thirty-two (76%) of temporal lobe patients became seizure-free (Engel Class I) vs 24 (68%) for the extratemporal group (Engel Class I). One patient (2%) in the temporal group had an Engel Class II outcome and one patient (3%) in the extratemporal group had the same Engel Class II outcome. Three patients (4%) manifested postoperative complications, and there were no deaths. Patients reported improvement in cognitive abilities, behavior, and quality of life after the surgery. Epilepsy surgery in children is effective and safe. Many children are seizure-free after the operation and remain so, although the results of temporal lobectomy are better than for extratemporal resections. There are few complications, and children often have an improved quality of life.

Communicating hydrocephalus caused by an unruptured perimedullary arteriovenous fistula in the lumbar region of an infant.

Spinal arteriovenous malformations are rare in children, although perimedullary arteriovenous fistulas (PMAVFs) may account for up to 24% of spinal arteriovenous malformations in this age group. Reported presentations of PMAVFs have included progressive or acute myelopathic symptoms, pain, hematomyelia, and subarachnoid hemorrhage. No known reports of an unruptured PMAVF causing communicating hydrocephalus have been previously published. A 17-month-old girl presented to the authors' clinic with a 6-month history of back and leg pain, gait regression, constipation, and marked lumbar hyperlordosis due to a PMAVF. A brain MRI study also demonstrated advanced hydrocephalus. The patient underwent embolization with Onyx of 2 feeding arteries from the right L-1 and 1 feeding artery from the left L-1 lumbar arteries. Postembolization follow-up imaging demonstrated a reduction in size of the L-1 pedicles and no residual supply of the fistula. Three-year clinical follow-up showed normal bowel and bladder function with significant improvements in the patient's back pain, gait, and hyperlordosis. The patient's ventricular enlargement improved without direct management of her hydrocephalus. To the authors' knowledge, this is the first reported case of communicating hydrocephalus caused by an unruptured PMAVF. The authors postulate that the origin of hydrocephalus was either central venous hypertension caused by the high-flow fistula or a change in fluid dynamics reducing CSF resorption through arachnoid granulations in the lumbar region of the spinal cord. The exact role that spinal arachnoid granulations play in CSF resorption is not currently known. Regardless of pathogenesis, initial treatment should focus on management of the fistula with additional hydrocephalus management only when necessary.