Peter Kan

Cellular phone use and brain tumor: a meta-analysis

BackgroundThe dramatic increase in the use of cellular phones has generated concerns about potential adverse effects, especially the development of brain tumors. We conducted a meta-analysis to examine the effect of cellular phone use on the risk of brain tumor development.MethodsWe searched the literature using MEDLINE to locate case-control studies on cellular phone use and brain tumors. Odds ratios (ORs) for overall effect and stratified ORs associated with specific brain tumors, long-term use, and analog/digital phones were calculated for each study using its original data. A pooled estimator of each OR was then calculated using a random-effects model.ResultsNine case-control studies containing 5,259 cases of primary brain tumors and 12,074 controls were included. All studies reported ORs according to brain tumor subtypes, and five provided ORs on patients with ≥10xa0years of follow up. Pooled analysis showed an overall OR of 0.90 (95% confidence interval [CI] 0.81–0.99) for cellular phone use and brain tumor development. The pooled OR for long-term users of ≥10xa0years (5 studies) was 1.25 (95% CI 1.01–1.54). No increased risk was observed in analog or digital cellular phone users.ConclusionsWe found no overall increased risk of brain tumors among cellular phone users. The potential elevated risk of brain tumors after long-term cellular phone use awaits confirmation by future studies.

Lack of efficacy of antibiotic-impregnated shunt systems in preventing shunt infections in children

ObjectiveShunt infection is a common and serious complication of cerebrospinal fluid (CSF) shunting most commonly caused by skin flora contamination at surgery. Recent studies indicate that the use of antibiotic-impregnated (AI) shunt systems may reduce the risk of postoperative shunt infections. We evaluated the incidence of shunt infections associated with the use of AI shunt catheters and compared it with the incidence associated with standard non-AI catheters.Materials and methodsAll shunt procedures performed by one surgeon using AI catheters were reviewed. An equal number of consecutive shunt procedures performed by the same surgeon using non-AI catheters were reviewed from the period immediately before the introduction of the AI system. Patients with <9xa0months of follow-up were excluded; all shunt infections and shunt-related complications were recorded. The proportions of infected shunts in the AI and control groups were compared using a χ2 analysis.ConclusionWe reviewed 160 shunt procedures (80 per group). The infection rate was 5.0% among patients with AI catheters compared with 8.8% in the control group (Pu2009=u20090.534, Fischer’s exact). The average time to infection was similar between the two groups. Among the AI group, the shunt infection rate did not differ between ventricular catheter, distal catheter revisions, and revisions of ventricular and peritoneal tubing. In contrast with other reports, we found no significant reduction in the pediatric CSF shunt infection rate with the use of AI shunt systems. Any recommendation for or against the routine use of AI systems in children requires a prospective, blinded, randomized-controlled trial with adequate power.

Os odontoideum: presentation, diagnosis, and treatment in a series of 78 patients

OBJECTnThe most contentious issue in the management of os odontoideum surrounds the decision to attempt atlantoaxial fusion in patients with asymptomatic lesions. The authors examined the clinical presentation and outcome in patients with os odontoideum who underwent surgical stabilization, with an emphasis on 3 patients who initially received conservative treatment and suffered delayed neurological injury.nnnMETHODSnSeventy-eight patients (mean age 20.5 years; median 15 years) were identified in a 17-year retrospective review. The median follow-up period was 14 months (range 1-115 months). Neck pain was the most common symptom (64%), and 56% of patients presented after traumatic injury. Eighteen patients had neurological signs or symptoms at presentation, and an additional 15 had a history of intermittent or prior neurological symptoms. Fifteen patients had undergone > or = 1 attempt at atlantoaxial fusion elsewhere.nnnRESULTSnSeventy-seven patients underwent posterior fusion and rigid screw fixation combined with a graft/wire construct: 75 had C1-2 fusion and 2 had occipitocervical fusion. One patient had an odontoid screw placed. Fusion was achieved in all patients at a median of 4.8 months (range 2-17 months). Approximately 90% of patients had resolution or improvement of their neck pain or neurological symptoms.nnnCONCLUSIONSnThe authors believe that patients with os odontoideum are at risk for future spinal cord compromise. Forty-four percent of our patients had myelopathic symptoms at referral, and 3 had significant neurological deterioration when a known os odontoideum was left untreated. This risk of late neurological deterioration should be considered when counseling patients. Stabilization using internal screw fixation techniques resulted in 100% fusion, whereas 15% of patients had previously undergone unsuccessful wire and external bracing attempts.

Outcomes after surgery for focal epilepsy in children

ObjectSurgery is an effective treatment for selected patients with intractable epilepsy. The authors report the outcomes of focal resection in a series of children suffering from intractable focal epilepsy treated at a single institution.MethodsThe authors retrospectively analyzed a series of 58 consecutive children who underwent surgery between 1998 and 2006 for intractable localized epilepsy at Primary Children’s Medical Center. Evaluation for surgery and follow-up was performed by the authors in the combined Pediatric Epilepsy Surgery Clinic.ResultsPreoperative seizure duration ranged from 6xa0months to 15xa0years. The cause of epilepsy was mesial temporal sclerosis (MTS) in 16 patients, dual pathology (MTS plus another lesion) in 3 patients, low-grade tumors in 16 patients, cortical dysplasia (CD) in 13 patients, cavernous malformation (CM) in 5 patients, and other conditions in 5 patients. In 33 cases, the lesions were in the temporal lobe, and in 25 cases, the lesions were extratemporal. At last follow-up, 74% (43/58) of all patients were seizure-free; seizure-free rates for specific conditions were 88% (14/16) for MTS, 33% (1/3) for dual pathology, 81% (13/16) for tumor, 62% (8/13) for CD, and 80% (4/5) for CM. Seizure-free rates were 85% (28/33) for temporal locations and 60% (15/25) for extratemporal locations. There were no permanent neurological complications or deaths.ConclusionSurgery for localized epilepsy in carefully selected children has good seizure control rates with minimal complications. Outcomes for patients with resections in temporal locations were better than those for patients with extratemporal resections.

The role of diffusion-weighted magnetic resonance imaging in pediatric brain tumors

ObjectivesDiffusion-weighted imaging (DWI) may enhance the radiographic diagnosis of pediatric brain tumors. This study reviews the DWI properties of pediatric brain tumors at our institution and examines their relationship to tumor grade and type.Materials and methodsThe preoperative DWI and apparent diffusion coefficient (ADC) characteristics of brain tumors in 41 children were compared with histologic diagnosis. Signal characteristics on DWI and ADC maps correlated well with tumor grade. High-grade lesions were hyperintense on DWI and hypointense on ADC maps. Sensitivity, specificity, positive predictive value, and negative predictive value were 70, 100, 100, and 91%, respectively. Signal characteristics did not differ among different tumors of the same grade. All primitive neuroectodermal tumors showed diffusion restriction whereas none of the ependymomas did.ConclusionsThe signal characteristics on DWI and ADC maps appeared to be strongly correlated to grade in pediatric brain tumors and they may assist with preoperative diagnostic predictions.

Peritumoral edema after stereotactic radiosurgery for intracranial meningiomas and molecular factors that predict its development

IntroductionStereotactic radiosurgery (SRS) is an effective treatment for small and medium-sized meningiomas. Although uncommon, peritumoral edema can develop as a delayed complication after SRS. The purpose of the study was to evaluate the clinical and molecular risk factors for peritumoral edema after SRS for intracranial meningiomas.MethodsWe retrospectively reviewed the results from 18 patients with intracranial meningiomas who underwent SRS. Tissue was obtained from 14 of these patients who also underwent surgery (13 before SRS). Peritumoral edema, before and after SRS, was estimated using the edema index. Quantitative differences in molecular markers of angiogenesis (VEGF, VRGFr) and hypoxia (HIF-1, GLUT-1, and CA-IX) as well as proliferative indices between patients with and without an elevated edema index after SRS were evaluated.ResultsOf the 18 patients studied, symptomatic peritumoral edema developed in three after SRS. They were treated with steroids and one required surgical intervention. The mean time to edema onset was 5.5xa0months, with an average duration of 16xa0months. Sagittal sinus occlusion and high-grade histology appear to be more common in the edema group. VEGF and HIF-1 were found in tumors with higher edema index and the elevation of these proteins was correlated with peritumoral edema after SRS. Proliferative index was not predictive for peritumoral edema.ConclusionClinical characteristics and molecular markers may identify patients with meningiomas at risk of peritumoral edema after SRS. Judicious use of steroids or perhaps the use of stereotactic fractionated radiation should be considered in these high-risk patients.

Radiographic features of tumefactive giant cavernous angiomas

SummaryBackground. Giant cavernous angiomas (GCAs) are very rare, and imaging features of GCAs can be very different from those of typical cavernous angiomas (CAs), making them a diagnostic challenge. The purpose of the study was to evaluate the radiographic features of GCAs, with an emphasis on the differentiating features from neoplastic lesions.n Methods. The neuroradiological findings of 18 patients who harbored a histologically verified GCA (CA of 4u2009cm or larger) were reviewed retrospectively. The magnetic resonance imaging (MRI) appearance, enhancement pattern, presence of edema or mass effect, size, and location of each lesion were recorded. When available, pertinent clinical information, including age, sex, and mode of presentation, was obtained.n Findings. Seizures, neurologic deficits, hemorrhage, and hydrocephalus were the most common presenting symptoms. The lesions were hyperdense and nonenhancing on computed tomography with frequent calcifications. On MRI, the lesions most commonly had a multicystic appearance, representing blood of various ages, and multiple complete hemosiderin rings. GCAs can present in any location with associating edema and mass effect, giving them a tumefactive appearance. No developmental venous anomaly was observed with any lesion.n Conclusions. Most GCAs in our series presented as multicystic lesions with complete hemosiderin rings on MRI, giving a “bubbles of blood” appearance. Although this characteristic feature is helpful in the diagnosis of many cases of GCAs, the correct diagnosis in the remaining cases may not be apparent until histopathological evaluation of the specimen is made.

Blood transfusions after thoracoscopic anterior thoracolumbar vertebrectomy

PurposeAnterior vertebral body reconstruction (AVBR) for trauma or tumor involves corpectomy and placement of hardware to reconstitute the anterior weight-bearing stability of the spine. We report our clinical experience with thoracoscopic techniques for AVBR.MethodsWe retrospectively analyzed patients who underwent thoracoscopic AVBR surgery for expandable cage placement. We report pathological condition, patient age, vertebral body level, operative time, estimated blood loss (EBL), and need for blood transfusion.ResultsTwenty-one expandable cages were placed thoracoscopically in 15 fractures and six tumors. In fracture cases, mean age, operative time, EBL, and transfusion rate were 36.7xa0years, 4.9xa0h, 543xa0mL, and 7% (1/15), respectively. In tumor cases, mean age, operative time, EBL, and transfusion rate were 61.9xa0years, 4.9xa0h, 758xa0mL, and 17% (1/6), respectively.ConclusionsThoracoscopic AVBR with expandable cages can be accomplished safely with acceptable operative times and blood loss and low transfusion rates.

Submandibular-infratemporal interpositional carotid artery bypass for cranial base tumors and giant aneurysms.

OBJECTIVE: Cerebral revascularization is an important strategy in the surgical management of some complex cranial base tumors and unclippable aneurysms. A high-flow bypass may be necessary in planned carotid occlusion or sacrifice. The cervical-to-supraclinoid internal carotid artery bypass or cervical carotid-to-middle cerebral artery bypass are useful procedures to bypass lesions at the base of the cranium. We describe technical modifications of the submandibular-infratemporal interpositional saphenous vein (or radial artery) graft bypass technique specifically designed to avoid removal of the zygoma. METHODS: The saphenous vein or radial artery interpositional graft is tunneled through a burr hole created in the floor of the middle fossa via a submandibular-infratemporal route avoiding removal of zygoma and attachments of the masseter or temporalis muscles. RESULTS: The technique is demonstrated in one patient with removal of a malignant cavernous sinus tumor and in another patient with an unclippable giant carotid bifurcation aneurysm. CONCLUSION: The advantages of this approach include preservation of the facial anatomy and creation of a short and safe route for passage of the saphenous vein or radial artery graft.

Primary spinal yolk sac tumor with brain metastasis: case report and review of the literature

SummaryObjectCentral nervous system primary germ cell tumors are typically pineal or suprasellar. Primary germ cell tumors of the spinal axis are very rare, with only a few case reports of germinomas and teratomas described in the literature.MethodsWe present the unique case of a 25-year-old woman with an intradural, extramedullary primary yolk sac tumor (YST) at and below the level of the conus medullaris. The patient was treated with a subtotal resection and within a month had rapid regrowth of her YST. She was subsequently treated with four cycles of chemotherapy (intravenous cisplatin and etoposide), 40-Gy fractionated focal external beam radiation to the spine, and consolidation with four additional cycles of chemotherapy (intravenous carboplatin, vinblastine, etoposide, and bleomycin). Despite an initial reduction in tumor size and clinical improvement in her neurologic exam, she re-presented a year after surgery with gross enlargement of her spinal tumor and CSF dissemination with metastasis to her brain. Despite further chemotherapy and radiotherapy, the patient died from her disseminated YST.ConclusionsThis case demonstrates that primary YSTs may occur in the spine, and like their intracranial counterparts, are associated with poor prognosis and dissemination through the neuroaxis. When feasible (no evidence of CSF dissemination, metastasis, or multifocal disease), optimal treatment includes as extensive resection of tumor as possible followed by adjuvant chemotherapy and radiation. The authors review the available literature on the treatment of intracranial malignant germ cell tumors, extrapolated to apply to the much rarer spinal lesions.