Neurointerventions in children: radiation exposure and its import.

BACKGROUND AND PURPOSE: Neurointerventions in children have dramatically improved the clinical outlook for patients with previously intractable cerebrovascular conditions, such as vein of Galen malformations and complex arteriovenous fistulas. However, these complex and sometimes lengthy procedures are performed under fluoroscopic guidance and thus unavoidably expose vulnerable pediatric patients to the effects of ionizing radiation. Recent epidemiologic evidence from a national registry of children who underwent CT scans suggests a higher-than-expected incidence of secondary tumors. We sought to calculate the predicted risk of secondary tumors in a large cohort of pediatric neurointerventional patients. MATERIALS AND METHODS: We reviewed our cohort of pediatric neurointerventions, tabulated radiation dose delivered to the skin, and calculated the range of likely brain-absorbed doses by use of previously developed mathematical models. The predicted risk of secondary tumor development as a function of brain-absorbed dose in this cohort was then generated by use of the head CT registry findings. RESULTS: Maximal skin dose and brain-absorbed doses in our cohort were substantially lower than have been previously described. However, we found 1) a statistically significant correlation between radiation dose and age at procedure, as well as number and type of procedures, and 2) a substantial increase in lifetime predicted risk of tumor above baseline in the cohort of young children who undergo neurointerventions. CONCLUSIONS: Although neurointerventional procedures have dramatically improved the prognosis of children facing serious cerebrovascular conditions, the predicted risk of secondary tumors, particularly in the youngest patients and those undergoing multiple procedures, is sobering.

The use of Onyx for embolization of central nervous system arteriovenous lesions in pediatric patients.

BACKGROUND AND PURPOSE: The safety and efficacy of Onyx for the embolization of central nervous system (CNS) arteriovenous (AV) lesions have been widely reported in adults. However, data describing the use of this agent in children are limited. This study presents our experience with Onyx in the treatment of CNS AV lesions in pediatric patients. MATERIALS AND METHODS: We retrospectively analyzed clinical and imaging records of 15 pediatric patients who underwent 36 transarterial embolizations by using Onyx for CNS AV lesions, from March 2007 through April 2009 at our institution. Underlying pathologies included brain AV malformations (AVMs) (n = 7), vein of Galen malformations (n = 4), dural AV fistulas (n = 2), and spinal AVMs (n = 2). For 7 procedures in very high-flow lesions, detachable coils were deployed before Onyx embolization, whereas in 29 procedures, Onyx was the sole embolic agent. The efficacy of embolization was judged by the residuum of AV shunting within the target region. RESULTS: Embolization was complete in 2 patients, nearly complete in 9 patients, and partial (and ongoing) in 4 patients. Following staged embolization, 7 patients underwent surgical resection without significant blood loss and with good functional outcome in all cases. Clinically silent non-target embolization was encountered in 2 of 36 procedures. After 3 of the 36 embolizations, patients developed transient neurologic symptoms, all of which resolved to baseline within 24 hours. There were no non-neurologic adverse events. There was no imaging evidence of infarct or hemorrhage. CONCLUSIONS: Onyx embolization of pediatric CNS AV lesions can be an efficacious treatment technique, with extremely low associated morbidity.

Moyamoya following cranial irradiation for primary brain tumors in children.

OBJECTIVE: To study the risk factors for the development of moyamoya syndrome after cranial irradiation for primary brain tumors in children. METHODS: We reviewed neuroimaging studies and dosimetry data for 456 children who were treated with radiation for a primary brain tumor and who were prospectively evaluated with serial neuroimaging studies and neurologic evaluations. A total of 345 patients had both adequate neuroimaging and radiation dosimetry data for further analysis. We used survival analysis techniques to examine the relationship of clinically important variables as risk factors for the development of moyamoya over time. RESULTS: Overall, 12 patients (3.5%) developed evidence of moyamoya. The onset of moyamoya was more rapid for patients with neurofibromatosis type 1 (NF1) (median of 38 vs 55 months) and for patients who received >5,000 cGy of radiation (median of 42 vs 67 months). In a multiple Cox proportional hazards regression analysis controlling for age at start of radiation, each 100-cGy increase in radiation dose increased the rate of moyamoya by 7% (hazard ratio [HR] = 1.07, 95% CI: 1.02 to 1.13, p = 0.01) and the presence of NF1 increased the rate of moyamoya threefold (HR = 3.07, 95% CI: 0.90 to 10.46, p = 0.07). CONCLUSIONS: Moyamoya syndrome is a potentially serious complication of cranial irradiation in children, particularly for those patients with tumors in close proximity to the circle of Willis, such as optic pathway glioma. Patients who received higher doses of radiation to the circle of Willis and with neurofibromatosis type 1 have increased risk of the development of moyamoya syndrome.

Craniopharyngioma presenting during pregnancy 4 years after a normal magnetic resonance imaging scan: case report.

OBJECTIVE AND IMPORTANCE: Craniopharyngiomas, epithelial tumors of the hypothalamic and pituitary region, are thought to have congenital origins. It has been postulated that hormonal influences may stimulate growth in adults. This report describes a case and reviews the literature. CLINICAL PRESENTATION: The case is discussed of a 39-year-old woman who experienced symptoms from a craniopharyngioma diagnosed during a pregnancy that resulted from in vitro fertilization. A magnetic resonance imaging scan performed 4 years previously had disclosed nothing abnormal. INTERVENTION: The patient underwent a right frontotemporal craniotomy with total resection of the suprasellar tumor, which was dissected from the pituitary stalk. CONCLUSION: This case suggests a possible link in the adult patient between the growth of this supposedly congenital tumor and hormonal stimulation.

Stereotactic radiotherapy for pediatric intracranial germ cell tumors.

PURPOSE: Intracranial germ cell tumors are rare, radiosensitive tumors seen most commonly in the second and third decades of life. Radiotherapy alone has been the primary treatment modality for germinomas, and is used with chemotherapy for nongerminomatous tumors. Stereotactic radiotherapy techniques minimize the volume of surrounding normal tissue irradiated and, hence, the late radiation morbidity. This study reports our experience with stereotactic radiotherapy in this group of tumors. METHODS AND MATERIALS: Between December 1992 and December 1998, 18 patients with intracranial germ cell tumors were treated with stereotactic radiotherapy. A total of 23 histologically proven tumors were treated. Thirteen patients had a histologic diagnosis of germinoma, and 5 patients had germinoma with nongerminomatous elements. Of those patients with a histologic diagnosis of germinoma, 5 had multiple midline tumors. The median age of the patients was 12.9 years (range, 5.6-17.5 years). RESULTS: A boost using stereotactic radiotherapy was delivered to 19 tumors following whole-brain radiation in 8 cases and craniospinal radiation in 11 cases. Three tumors were treated with stereotactic radiotherapy to the tumor volume alone following chemotherapy, and 1 tumor received a boost using stereotactic radiosurgery following craniospinal radiation. A median dose of 2520 cGy (range, 1500-3600) cGy was given to the whole brain, and a median dose of 2160 (range, 2100-2600) cGy was given to the spinal field. The median boost dose to the tumor was 2600 (range, 2160-3600) cGy, given by stereotactic radiotherapy delivered to the 95% isodose line. At a median follow-up time of 40 (range, 12-73) months, no local or marginal recurrences were reported in patients with germinoma. Two patients with nongerminomatous tumors have relapsed. One had elevation of tumor markers only at 37 months following treatment, and the other had persistent disease following chemotherapy and radiation therapy. Eight patients documented pituitary-hypothalamic dysfunction; in 7 (87.5%) of these patients, the dysfunction was present before commencing radiotherapy. Four patients (22%) developed newly diagnosed diabetes insipidus following surgery. Three patients (17%) received antidepressant medication at follow-up. CONCLUSION: Our series shows that stereotactic radiotherapy is achievable and well tolerated in this group of patients. Longer follow-up is required to fully assess the impact on long-term toxicity. Psychologic assessment of mood and affect should be performed as part of routine follow-up in this group of adolescent children.

Membranous obstruction of the fourth ventricle outlet. A case report.

We report the case of a 15-year-old girl with amenorrhea and a several-week history of headache. After the diagnosis of membranous obstruction of the foramen of Magendie suggested by MRI, suboccipital craniotomy for removal of the membrane was carried out. The patient made an excellent postoperative recovery, and postoperative phase-contrast MRI demonstrated patent cerebrospinal fluid (CSF) pathways at the level of the foramina of Magendie and Luschka. We believe that this case is of interest because of the unequivocal evidence on MRI studies of the occlusion of the foramen of Magendie preoperatively, and because of the dramatic postoperative MRI findings demonstrating the effectiveness of the surgical procedure both in terms of ventricular size and CSF flow characterization.

Proton magnetic spectroscopic imaging of the child's brain: the response of tumors to treatment.

Our aim was to determine and/or predict response to treatment of brain tumors in children using proton magnetic resonance spectro-scopic imaging (MRSI). We studied 24 patients aged 10 months to 24 years, using MRI and point-resolved spectroscopy (PRESS; TR 2000 TE 65 ms) with volume preselection and phase-encoding in two dimensions on a 1.5 T imager. Multiple logistic regression was used to establish independent predictors of active tumor growth. Biologically vital cell metabolites, such as N-acetyl aspartate and choline-containing compounds (Cho), were significantly different between tumor and control tissues (P < 0.001). The eight brain tumors which responded to radiation or chemotherapy, exhibited lower Cho (P = 0.05), higher total creatine (tCr) (P = 0.02) and lower lactate and lipid (L) (P = 0.04) than 16 tumors which were not treated (except by surgery) or did not respond to treatment. The only significant independent predictor of active tumor growth was tCr (P < 0.01). We suggest that tCr is useful in assessing response of brain tumors to treatment.

Long-term outcome for patients with split cord malformation.

OBJECT: Split cord malformations (SCMs) are relatively rare forms of occult spinal dysraphism (OSD) and tethered spinal cord syndrome. The majority of these cases present in early childhood, with neurocutaneous stigmata being an early presenting feature. Prophylactic detethering surgery is advocated by most neurosurgeons due to the risk of neurological deterioration over time caused by patient growth and activity. However, unlike other forms of OSD, the course of SCM progression after surgery is not well understood, and little has been published about long-term followup results. In this study the authors review the results obtained in 16 patients in whom the senior author performed surgery over a 13-year period (average length of follow up almost 8 years). METHODS: Presentation, surgical approach, and outcome are evaluated, and the long-term outcome of neurological status, pain, bowel/bladder disturbance, and spinal deformities are emphasized. CONCLUSIONS: The primary conclusion is that patients with SCM generally tolerate surgery well and experience few complications. Neurological deterioration is rare except in cases in which retethering occurs, (two patients in this series). Although impaired bowel and bladder function was stabilized or improved and pain was reliably relieved postoperatively, preexisting vertebral column deformities usually progressed after surgery and, in most cases, required spinal fusion.

Memory deficits among children with craniopharyngiomas.

OBJECTIVE: To describe neuropsychological functioning (with a specific focus on cognition and memory) after surgical treatment of craniopharyngiomas. METHODS: Sixteen patients who were between 6 and 15 years of age at the time of surgery comprised the sample. Each child had been treated for a craniopharyngioma with surgery only, on Dana-Farber Cancer Institute Protocol 92-077. RESULTS: The overall level of cognitive functioning was well within the average range, with both language and visuospatial functioning being generally intact; however, specific memory problems, in both the language and visuospatial domains, were evident. CONCLUSION: Although general cognitive functioning was intact after the surgical treatment of craniopharyngiomas, difficulties in the retrieval of learned information were observed. Neuropsychological assessments, with a focus on memory recall, should be a component of the medical management plan for each child.

Neurological dysfunction associated with postoperative cerebellar mutism.

BACKGROUND AND OBJECTIVES: The postoperative cerebellar mutism syndrome (CMS) is an unique acute postoperative complication characterized by transient decrease in speech output (often mutism), apathy, irritability as well as global cerebellar dysfunction. As much as 25% of patients undergoing a resection of a cerebellar or IV ventricular tumor may develop such a syndrome. In this retrospective study we characterize the clinical features of the CMS and explore potential etiologic mechanisms. METHODS: We conducted a retrospective analysis of medical records and imaging tests of 8 consecutive patients with the CMS identified through the database of the Children's Hospital and Dana-Farber Cancer Institute, Boston, and compared with a control group of 8 unaffected children undergoing a comparable tumor resection. RESULTS: In contrast to the control group, children in the affected group had marked decrease in speech output and comprehension, apathy and lack of initiative, inattention, persistent eye closure, flaccid hemiparesis and a severe global cerebellar dysfunction. Swallowing difficulties and bowel and bladder dysfunction were also observed. The median duration of the syndrome as judged by the persistence of the communication abnormalities was 4 weeks. The recovery was near complete with exception for a persistent global cerebellar dysfunction. A comparison of CT and MRI scans of children in both groups failed to identify distinguishing features. CONCLUSION: A surgical lesion of the midline cerebellum can cause a complex neurological dysfunction such as the CMS. Thus, we postulate that the cerebellum and its connections function as a 'modulatory system' in control of both motor and non-motor functions, including attention and language.

De novo translocation (8;12) and frontofacionasal dysplasia in a newborn boy.

We describe a newborn boy one of triplets, whose karyotype was 46,XY, t(8;12)(q22;q21). Prenatal diagnosis of multiple craniofacial anomalies had been made. Following delivery, the patient was thought to exhibit findings consistent with a diagnosis of frontofacionasal dysostosis. We hypothesize that one of the break points of this translocation may involve a gene essential to craniofacial development.

The Department of Defense laboratory-based global influenza surveillance system.

Military global influenza surveillance began in 1976 as an Air Force program. In 1997, the Department of Defense (DoD) Global Emerging Infections Surveillance and Response System expanded the program to include all services. Also included were local residents in areas where DoD overseas research activities operated. This new, worldwide DoD surveillance infrastructure provides valuable information and can respond quickly to outbreaks. This was demonstrated during the current influenza season when a suspected outbreak was reported in Panama. In less than 3 weeks, specimens were collected, transported, and cultured, and isolates were subtyped and sent to the Centers for Disease Control and Prevention for further studies. This influenza surveillance initiative combines viral isolation, antigenic characterization, and molecular sequencing with clinical and public health management of information. The information obtained is shared with the Centers for Disease Control and Prevention and the World Health Organization and has contributed to important decisions in influenza vaccine composition.

The effect of surgery for split spinal cord malformation on neurologic and urologic function.

The split spinal cord malformation (SSCM) is an occult spinal dysraphism which causes tethering of the spinal cord. We performed a retrospective analysis of 15 patients who had split cord malformations (without associated open neural tube defect) who underwent both pre- and postoperative urodynamic studies (UDS) in order to determine if a significant percentage of these patients, even in the absence of overt urologic symptoms, had evidence of urologic dysfunction. Eleven patients presenting in early childhood and 4 patients presenting later in life are reviewed. Despite the lack of preoperative urologic symptoms in almost all patients, 73% of patients had voiding abnormalities on formal testing. UDS on these patients before and after surgery was a useful adjunct to perioperative management and decision making, helped define the success of surgery, and gave objective information for cases in which retethering was suspected.

Spontaneous thrombosis of vein of Galen aneurysmal malformation.

Two cases of aneurysmal malformations of the vein of Galen (AVG) with spontaneous thrombosis are reported. Angiogram and MRI before thrombosis demonstrated AVGs with slow arteriovenous shunts and associated stagnation of contrast in the venous sac secondary to severe outflow restriction. Based on these findings, one patient was managed conservatively, and the other underwent placement of a ventriculoperitoneal shunt. Surveillance of the lesions with subsequent MRIs revealed spontaneous thrombosis of the AVGs with excellent clinical outcomes. Proposed mechanisms of spontaneous thrombosis include slow flow shunts, obstruction of the venous outflow or obstruction of the feeding artery. Similar cases in the literature are reviewed with special emphasis on diagnostic tests, symptomatology, mechanisms of thrombosis and therapeutic options.