Spinal cord injuries without radiographic abnormality at two pediatric trauma centers in Ontario.

BACKGROUND: Spinal cord injury without radiographic abnormality (SCIWORA) represents a traumatic myelopathy, either transient or permanent, that is not associated with visible vertebral fractures or ligamentous abnormalities on plain radiographs or CT. MRI has become essential in the diagnosis and evaluation of trauma patients and in predicting the long-term neurological outcome. METHODS: The medical charts of 578 children with vertebral trauma at the Children's Hospital of Eastern Ontario and the Hospital for Sick Children were retrospectively reviewed. RESULTS: Forty-five patients were identified as having traumatic myelopathy. Three of these patients had SCIWORA. Two sustained thoracic spinal cord injuries as a result of motor vehicle accidents and permanent neurological deficits. The third was involved in a sports-related injury and sustained a cervical spine injury that improved in 48 h. CONCLUSIONS: SCIWORA is uncommon. The serious neurological sequelae that can result from a missed diagnosis merit more attention in identifying a spinal lesion in children with traumatic myelopathy. MRI has played a valuable role in this respect and may be even more predictive of outcome than the presenting neurological findings. The SCIWORA acronym can be modified to SCIWONA (spinal cord injury without neuroimaging abnormality) in order to highlight the importance of MRI in the prognosis.

Brainstem compression: a predictor of postoperative cerebellar mutism.

PURPOSE: Cerebellar mutism is a common complication of posterior fossa tumor resection. We observed marked, preoperative brainstem compression on MR imaging, among patients who developed postoperative mutism. This study was designed to investigate if an association was indeed present. MATERIALS AND METHODS: Patients (18 months-18 years) undergoing resection of a midline, posterior fossa tumor were retrospectively reviewed. Demographic data, tumor pathology, mutism onset and duration, and postoperative complications were obtained from hospital records. Pre- and postoperative MR images were studied to assess tumor size and the severity of pons compression (an estimate of the mechanical and distortional forces imparted by the tumor). RESULTS: Patients with mutism showed greater preoperative pons compression and a greater increase in postoperative pons diameter. CONCLUSION: We predict that brainstem compression may represent white-matter injury from (1) surgical manipulation and traction, and (2) axonal damage caused by the release of the tumor's compressive force and ensuing axon distortion and dysfunction. The results provide support that mutism may be largely caused by white-matter damage disrupted axon integrity and function.

Posterior fossa dimension and volume estimates in pediatric patients with Chiari I malformations.

INTRODUCTION: Chiari I malformations (CMI) involve pathological hindbrain abnormalities reported to be correlated with a hypoplastic posterior fossa. CMI was traditionally characterized by the downward herniation of the cerebellar tonsils with a descent of 5 mm or more below the foramen magnum. The fullness of the cisterna magna and CSF flow at the level of the cervicomedullary junction have been shown to be more useful in selecting symptomatic patients for surgical decompression. The present study calculates posterior fossa dimension and volume estimates in pediatric patients using magnetic resonance imaging. The combination of neuroradiological and clinical findings is used to re-examine the criteria used for diagnosis and treatment of pediatric CMI patients. MATERIALS AND METHODS: A retrospective chart review was conducted on patients who were admitted to the Division of Neurosurgery of the Children's hospital of Eastern Ontario between 1990 and 2007. Clinical and radiological assessments were performed on all patients. Posterior fossa volumes (PFV) and intracranial volumes (ICV) were measured from sagittal head magnetic resonance imaging scans using the Cavalieri method. RESULTS: Sixty-one CMI patients were identified. There were 32 male and 29 female patients with a mean age of 10 years (range: 8 weeks-18 years). Thirty-four (55%) of these patients were symptomatic with scoliosis (38%), suboccipital headaches (29%), and motor/sensory deficits (26%) being the most prominent symptoms. The mean PFV/ICV ratio for all the CMI patients (0.110) was found to be statistically smaller than that of the control patients (0.127, p=0.022). Mean PFV/ICV ratios for asymptomatic and symptomatic CMI patients were found to be similar for children aged 0-9 years (p=0.783) but different for children aged 10-18 years (p=0.018). DISCUSSION: Mean PFV values were found to be smaller in pediatric CMI patients than control patients; this complements earlier studies in adults and supports the present theory concerning the pathophysiological mechanism of CMI. Subtle morphometric differences among asymptomatic and symptomatic patients aged 0-9 years stress the importance of monitoring asymptomatic patients for the onset of symptoms in their adult years. Symptom development in CMI is likely multifactorial and is much more extensive than the degree of cerebellar tonsillar herniation.

Radioisotope shuntograms at the Children's Hospital of Eastern Ontario.

INTRODUCTION: Nuclear medicine shuntograms using the radiotracer technetium-99m diethylenetriaminepentaacetic acid have been used for many years as an additional method to assess shunt patency and performance. METHODS: The medical records of all children who had shuntograms performed at the Children's Hospital of Eastern Ontario between January 13, 2000, and January 10, 2003, were retrospectively reviewed. There was a total of 68 procedures in 56 patients with an average age of 9 years 3 months. During the same period there were 123 shunt revisions. RESULTS: Forty-two shuntograms were reported as normal. Of these, ten were identified to be false negative. Two children with fractured shunts had shuntograms performed in order to assess for cerebrospinal fluid flow patency; the shuntograms were identified to be normal, confirming shunt dependence, and the shunt replaced. Twenty-six shuntograms were reported as abnormal in 24 patients; 17 went on to have surgery and the shunt malfunction was confirmed. Seven patients did not require surgery: five were declared shunt independent, two patients clinically improved after severe constipation was treated. CONCLUSIONS: Approximately one fourth of all shuntograms reported as normal are not (false-negative rate=25%). Review of five other major studies between 1980 and 2003 have reported false-negative rates between 2 and 36%, which may be explained by variations in shuntogram protocols. A standardized method is proposed.

Hydrocephalus as the initial presentation of a spinal cord astrocytoma associated with leptomeningeal spread.

A 3-year-old boy presented with headaches, vomiting, lethargy and papilledema. Communicating hydrocephalus along with transependymal fluid absorption and meningeal contrast enhancement was identified on CT. The enhancement was initially thought to be the result of a partially treated meningitis (child was previously on oral antibiotics for a presumed mycoplasma pneumonia). A right ventricular-peritoneal shunt was placed. CSF studies procured during the procedure were all normal. In contrast, CSF from a lumbar puncture contained a high protein, and cytology was highly suspicious for malignancy. Spine MRI showed diffuse leptomeningeal enhancement and a 1.5-cm intramedullary lesion at T12-L1 associated with minimal edema. The lesion was subtotally resected (70%) and diagnosed as an astrocytoma (mostly Kernohan grade 2 but with areas of grade 3). Chemotherapy was administered and follow-up spine MRI at 2 months did not reveal any residual tumor, however, the leptomeningeal enhancement persisted. Sixteen months later, at the completion of the chemotherapy and radiation therapy, the spine MRI remained unchanged. Neurological examination has always been normal. This case illustrates how a spinal cord astrocytoma can metastasize via spinocranial dispersion and present early with hydrocephalus rather than myelopathy.

Delayed onset of vocal cord paralysis after explantation of a vagus nerve stimulator in a child.

INTRODUCTION: Vagus nerve stimulation for the management of intractable seizure disorders is increasingly being used, especially in younger children. Although complications such as infection or vocal cord paralysis are uncommon, some may be unreported. CLINICAL PRESENTATION: A 3.5-year-old boy with intractable complex partial and generalized seizures had a left vagus nerve stimulator (VNS) successfully implanted. Two weeks later, the cervical incision showed signs of infection, antibiotics were started, and the VNS generator and leads were explanted. Three weeks later the child's mother noted a change in the voice of her son, as well as increased coughing and gagging. Flexible laryngoscopy identified a left vocal cord paralysis, which eventually resolved after 6 months. CONCLUSION: Infection requiring explantation of a VNS is uncommon. The risk is higher in younger children, especially in those who are developmentally delayed. These children may continuously drool, with saliva or food soiling the fresh incision, or even pick at the incision to the point of twisting or even pulling out the electrodes. Less common is a vocal cord paralysis, especially occurring in a delayed fashion.

Identification of an arteriovenous fistula in a child. Case report and review of the literature.

BACKGROUND: A 6-year-old girl sustained a subarachnoid hemorrhage after a mild head injury and was discovered to have an arteriovenous fistula (AVF). INVESTIGATIONS AND TREATMENT: The etiology of subarachnoid hemorrhage was not evident on the initial brain CT. Brain CT with CT angiography identified the lesion. The AVF was further imaged with brain MRI followed by cerebral angiography and successfully embolized. OUTCOME: The child did not suffer any neurological sequelae.

Medulloblastoma in children--the Ottawa experience.

A retrospective review of 36 children diagnosed with medulloblastoma in the Ottawa area between 1974 and 1997 was completed (mean age 7.8+/-4.2 years, range 1.2-15.3 years). Via a suboccipital approach, complete tumor resection was achieved in 75% and subtotal resection (>90%) in 25%, without any operative mortality. The tumor was located in the vermis in 39% and in the cerebellar hemisphere in 11%; it occupied both locations in 50%. In 47% of the children a ventriculoperitoneal shunt was required. Postoperatively, craniospinal radiation at 3600 cGy with a boost to the posterior fossa was administered. Chemotherapy was used in 56%. The 1-year survival rate was 92%, and survival plateaued at 54% at 5 years. Children less than 3 years of age fared worse than those over 3 years old. While the male-to-female ratio was 1.6:1, there was no gender difference in survival. Chang's classification was used to grade the tumors. T stage did not have an impact on survival, but M stage did. No statistically significant difference in survival was found between the patients who had a total resection and those who had a subtotal resection. There was no difference in survival in terms of tumor location, hydrocephalus or ventriculoperitoneal shunt. Chemotherapy showed no survival benefit. The recurrence rate was 26%, and its timing followed Collin's law. Recurrence led to death within 1-9 months. GH deficiency was diagnosed in 5 patients and hypothyroidism in 4 patients. The mean follow-up time was 4.4+/-3.7 years, with a range of 2.5 months to 16.5 years. Fourteen patients died, 5 were lost to follow-up, and 7 were transferred to adult care without persistent disease. Ten children are presently being followed up by the Neuro-oncology Clinic. Four children continue to be followed through psychology services. Our results are comparable to those in larger series, and are similar to those of the Montreal Children's Hospital.

Temporal lobe focal cortical dysplasia: MRI imaging using FLAIR shows lesions consistent with neoplasia.

Focal cortical dysplasia (FCD), a form of neuronal migration disorder, is a malformative lesion of the neocortex that occurs during development of the brain. It can cause partial and generalized epilepsy. Seizures occur at an early age and are often resistant to medication. Surgical resection has been found to be beneficial in these patients. Dual pathology, in the form of mesial temporal sclerosis, has been associated with FCD. At the Children's Hospital of Eastern Ontario, four patients with temporal lobe FCD have recently, been identified. This paper discusses how these children presented and how they were managed, with particular emphasis on their MRI findings and differential diagnoses. In three of the four patients neuroimaging studies showed lesions consistent with a neoplastic process because of the large volume and mass effect. Radiologically, FCD may mimic the MRI appearance of tumors, such as dysembryoplastic neuroepithelial tumors, primitive neuroectodermal tumors, gangliogliomas, oligodendrogliomas, and astrocytomas. These lesions are best visualized on fluid-attenuated inversion recovery (FLAIR) imaging, a technique that has recently become applicable in the clinical setting, as we help demonstrate in this series. With better MRI capability, milder forms of FCD and microdysplasia may be distinguished.

Treatment options for spasticity in children

Partial dorsal root rhizotomy and intrathecal administration of baclofen are two modalities used to treat spasticity in children. Each has its own inclusion criteria and mechanism of action. Both have been proven to relieve spasticity, and both have their particular side effects and complications. Programmable pumps for the accurate and reliable administration of intrathecal baclofen are expensive and demand a lifelong commitment to medication refill and hardware reimplantation. Partial dorsal root rhizotomy is a one-time surgical procedure, which differs from one center to another. It requires a team approach for patient selection and to determine whether other treatment options should take precedence. It also requires a period of postoperative reeducation in the form of physiotherapy. While some centers use intraoperative nerve root stimulation and muscle response recording as a guidance tool for rootlet sectioning, others claim equally good results without the added time-consuming technology.

Negative-pressure hydrocephalus.

Two cases of children with closed myelodysplasia, Arnold-Chiari malformation, and shunted hydrocephalus who underwent spinal arachnoid cystopleural shunting are presented. Postoperatively, both patients developed craniovertebral symptomatology accompanied by radiologically documented ventricular dilation in spite of negative intracranial pressure and functional ventriculoperitoneal (VP) shunts. Both patients recovered after the cystopleural shunts were revised to increase the resistance to flow within the system. The authors believe that some communication between the arachnoid cyst and the subarachnoid space existed in both cases and that the negative pleural pressure was transmitted preferentially to the spinal and cerebral convexity subarachnoid spaces with relative sparing of the ventricular system. A transmantle pressure gradient was thereby established, leading to ventricular dilation. The authors further suggest that a craniospinal gradient was possibly established as well, leading to craniovertebral symptomatology in the patients. Return of flow in the VP shunts was obtained by correcting this iatrogenic transmantle pressure gradient.

Effect of methylprednisolone on nitrogen dioxide (NO2)-induced pulmonary edema in guinea pigs.

The treatment of nitrogen dioxide (NO2)-induced lung edema is controversial. In addition, mechanisms and patterns of interstitial edema formation in this form of increased permeability edema are unclear. To ascertain if methylprednisolone (MP) is effective in the therapy of NO2-induced edema, we exposed 108 unaesthetized guinea pigs, in groups of 12, to 277-448 ppm.hr NO2: in 60, we administered MP just before, and in 48 immediately after exposure. In each group, half the animals were randomly assigned to receive 30 mg/kg MP ip, and the other half saline. Mortality rates and lung water with wet weight/dry weight (W/D) ratios were calculated. Alveolar edema, periarterial interstitial edema, and NO2-induced bronchiolitis were graded semiquantitatively by light microscopy from freeze-substituted middle (ML) and lower lobes (LL). We found NO2 produced an exposure-dependent increase in lung water (R = 0.70, p less than 0.01). Treatment with MP preexposure produced a fourfold reduction mortality, and and a significant fall in W/D ratios and in alveolar and interstitial edema. No difference in the degree of acute bronchiolitis was found between treated and untreated animals, although ML had significantly more inflammation than LL. Treatment with MP immediately after NO2 was ineffective since mortality rates, W/D ratios, and alveolar and interstitial edema were not lower in the treated animals; there was significantly more intestitial edema in the middle lobes of the latter. Both LL and ML had equally abundant alveolar edema, but LL had significantly more interstitial edema, supporting our previous findings that in NO2-induced edema interstitial fluid accumulation follows alveolar flooding, with interlobar discrepancies probably due to differences in lung volume or in ventilation.

Pattern of fluid accumulation in NO2-induced pulmonary edema in dogs. A morphometric study.

To ascertain whether the pattern of fluid accumulation could be altered by an agent introduced through the airways, the authors studied the physiology and morphology of 11 dogs exposed to 150-494 ppm.hr NO2 and compared them with 3 new and 5 previously reported control dogs. NO2 caused a partly reversible decrease in systemic arterial pressure and cardiac output, a fall in arterial PO2, and rapid shallow breathing, while pulmonary arterial and wedge pressures remained normal. Post mortem, lower (LL) and middle (ML) lobes were frozen, sections fixed for light microscopy by freeze-substitution, and wet weight/dry weight (W/D) ratios were measured. Alveolar edema was graded, and the distribution of interstitial edema around arteries and veins and within bronchovascular bundles was studied with morphometry: edema ratios (ER) were calculated as area of interstitium/area of vessel or airway. We found that NO2 produced an exposure-dependent increase in lung water (r = 0.73), and that both LL and ML had similar W/D ratios (7.77 and 8.39, respectively) and percent alveolar edema (30% and 34%). Morphometry of interstitial edema showed that the ER for vessels and airways of edematous LL were essentially similar to controls, while those of the ML were markedly increased. It is concluded that NO2 produces exposure-related lung edema and preferential alveolar flooding with probable secondary interstitial accumulation. The discrepancies in interstitial edema between middle and lower lobes may be due to differences in lung volume or in ventilation.

Catalase, superoxide dismutase, and the production of O2-sensitive mutants of Bacillus coagulans.

A number of facultatively anaerobic members of the genus Bacillus were screened for their catalase, diaminobenzidine peroxidase, and superoxide dismutase activities. A strain of Bacillus coagulans (7050) lacking peroxidatic activity and containing single catalatic and superoxide dismutase activities was selected. Responses of the superoxide dismutase activity and catalase level to the partial pressure of oxygen, and Fe and Mn levels, as well as to aerobic and fermentative metabolism, were determined. There appeared to be a relationship between high endogenous catalase levels and the high H2O2 evolution and KCN insensitivity of B. coagulans respiration. Bacillus coagulans 7050 was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine and screened for the expression of oxygen intolerance. All of the 38 stable oxygen sensitive mutants obtained had very low or completely absent catalatic activity and catalase protein. No mutant lacked superoxide dismutase, although five showed significantly lowered levels of the enzyme. Exogenous bovine liver catalase restored aerotolerance and reduced cell pleomorphism in the mutants.