Ependymoma Presenting as a -Rim-Enhancing Lesion in the Brainstem.

INTRODUCTION: The posterior fossa is the most common intracranial location for pediatric ependymoma. While ependymoma usually arises from the ventricular lining of the fourth ventricle as a solid mass, it rarely originates from the brainstem. Grade II ependymomas also infrequently appear as a cavitary ring-enhancing lesion. CASE PRESENTATION: We describe a case of a 6-year-old boy with an ependymoma arising within the medulla with imaging features of a thick-walled rim-enhancing cavitary lesion. A stereotactic biopsy was obtained which confirmed a grade II ependymoma. The patient received focal proton beam radiation therapy and is doing well with no concerns for disease progression at 28 months after diagnosis. CONCLUSION: Posterior fossa ependymomas typically arise from ependymal cells within the fourth ventricle or foramina of Luschka. They rarely invade or arise within the brainstem parenchyma. Our case had atypical imaging findings in addition to the atypical tumor location. The lesion was described as a thick-walled rim-enhancing focal cystic necrotic lesion centered within the medulla with surrounding nonenhancing expansile infiltrative changes. Ring-enhancing lesions can be seen in patients with anaplastic ependymoma, but is not commonly reported in grade II ependymomas. In summary, this report highlights a unique case of a posterior fossa ependymoma in a pediatric patient arising in an atypical brainstem location as well as having unique imaging features.

Estimation of normal computed tomography measurements for the upper cervical spine in the pediatric age group.

OBJECT: Upper cervical spine injuries in the pediatric age group have been recognized as extremely unstable from ligamentous disruption and as potentially lethal. Few measurement norms have been published for the pediatric upper cervical spine to help diagnose this pathological state. Instead, adult measurement techniques and results are usually applied inappropriately to children. The authors propose using high-resolution reconstructed CT scans to define a range of normal for a collection of selected upper cervical spine measurements in the pediatric age group. METHODS: Sagittal and coronal reformatted images were obtained from thin axial CT scans obtained in 42 children (< 18 years) in a 2-month period. There were 25 boys and 17 girls. The mean age was 100.9 months (range 1-214 months). Six CT scans were obtained for nontrauma indications, and 36 were obtained as part of a trauma protocol and later cleared for cervical spine injury. Six straightforward and direct linear distances-basion-dental interval (BDI); atlantodental interval (ADI); posterior atlantodental interval (PADI); right and left lateral mass interval (LMI); right and left craniocervical interval (CCI); and prevertebral soft-tissue thickness at C-2-that minimized logistical and technical distortions were measured and recorded. Statistical analysis including interobserver agreement, age stratification, and sex differences was performed for each of the 6 measurements. RESULTS: The mean ADI was 2.25 ± 0.24 mm (± SD), the mean PADI was 18.3 ± 0.07 mm, the mean BDI was 7.28 ± 0.10 mm, and the mean prevertebral soft tissue width at C-2 was 4.45 ± 0.43 mm. The overall mean CCI was 2.38 ± 0.44 mm, and the overall mean LMI was 2.91 ± 0.49 mm. Linear regression analysis demonstrated statistically significant age effects for PADI (increased 0.02 mm/month), BDI (decreased 0.02 mm/month), and CCI (decreased 0.01 mm/month). Similarly significant effects were found for sex; females demonstrated on average a smaller CCI by 0.26 mm and a smaller PADI by 2.12 mm. Moderate to high interrater reliability was demonstrated across all parameters. CONCLUSIONS: Age-dependent and age-independent normal CT measurements of the upper cervical spine will help to differentiate physiological and pathological states in children. The BDI appears to change significantly with age but not sex; on the other hand, the LMI and ADI appear to be age-independent measures. This preliminary study suggests acceptable levels of interrater reliability, and further expanded study will aim to validate these measurements to produce a profile of normal upper cervical spine measurements in children.

Pathologic fractures in children with acute Staphylococcus aureus osteomyelitis.

BACKGROUND: Osteomyelitis is a common pediatric musculoskeletal infection. This infection can weaken the normal bone structure, resulting in the risk of a pathologic fracture. The purpose of this study was to evaluate the risk factors for pathologic fracture in children with Staphylococcus aureus osteomyelitis. METHODS: Seventeen children who were treated for a pathologic long-bone fracture secondary to Staphylococcus aureus osteomyelitis between January 2001 and January 2009 at a tertiary-care pediatric hospital were identified. These patients were compared with a control group consisting of forty-nine children with Staphylococcus aureus osteomyelitis without a fracture who were matched for age, sex, and methicillin susceptibility. A retrospective review of the clinical records, magnetic resonance imaging (MRI) studies, and microbiologic findings was performed. RESULTS: Patients who developed a fracture presented with osteomyelitis at a mean age of 8.8 years (range, two to seventeen years). Fifteen of the seventeen patients had methicillin-resistant Staphylococcus aureus (MRSA) isolates, and two had methicillin-susceptible Staphylococcus aureus (MSSA). The mean time from disease onset to fracture was 72.1 days (range, twenty to 150 days). The duration of hospitalization, number of surgical procedures, duration of antibiotic treatment, and total number of complications differed significantly between the two groups. MRI studies at the time of admission demonstrated a significantly greater prevalence of subperiosteal abscess and greater circumferential size of such an abscess in the patients with a fracture. A sharp zone of abnormally diminished enhancement of the marrow was also more common in these patients. The USA300-0114 pulsotype was more commonly associated with an elevated likelihood of fracture. CONCLUSIONS: Staphylococcus aureus osteomyelitis is a serious infection that may predispose children to pathologic fractures. Protected weight-bearing and activity restriction are recommended in children with Staphylococcus aureus osteomyelitis who have the risk factors demonstrated in this study.

Hereditary neuropathy with liability to pressure palsies: case report and discussion.

Hereditary neuropathy with liability to pressure palsies (HNPP) is an uncommon diagnosis that should be considered in patients with multiple compressive neuropathies. We present the case of a woman who presented with bilateral hand numbness and weakness. Electrodiagnostic testing revealed bilateral carpal tunnel syndrome, bilateral ulnar neuropathy at the elbow, left peroneal neuropathy at the fibular head, and a primarily demyelinating generalized sensorimotor neuropathy. Subsequent genetic testing identified a deletion at chromosome 17p11.2 to confirm the diagnosis of HNPP. Treatment of this largely self-limiting disease is controversial, and this patient suffered minimal disability with treatment including splinting and surgical releases.