Kevin Chao

MRI Surrogates for Molecular Subgroups of Medulloblastoma

These authors seek to establish the imaging features that would allow classification of medulloblastomas according to their genetic attributes. In nearly 100 tumors they found that groups 3 and 4 occurred predominantly in the fourth ventricle, wingless ones were located in the cerebellar peduncles or CPA region, and sonic hedgehog tumors were present in cerebellar hemispheres. Midline group 4 tumors showed minimal contrast enhancement. Thus, tumor location and contrast-enhancement patterns may be predictive of the molecular subtypes of medulloblastoma. BACKGROUND AND PURPOSE: Recently identified molecular subgroups of medulloblastoma have shown potential for improved risk stratification. We hypothesized that distinct MR imaging features can predict these subgroups. MATERIALS AND METHODS: All patients with a diagnosis of medulloblastoma at one institution, with both pretherapy MR imaging and surgical tissue, served as the discovery cohort (n = 47). MR imaging features were assessed by 3 blinded neuroradiologists. NanoString-based assay of tumor tissues was conducted to classify the tumors into the 4 established molecular subgroups (wingless, sonic hedgehog, group 3, and group 4). A second pediatric medulloblastoma cohort (n = 52) from an independent institution was used for validation of the MR imaging features predictive of the molecular subtypes. RESULTS: Logistic regression analysis within the discovery cohort revealed tumor location (P < .001) and enhancement pattern (P = .001) to be significant predictors of medulloblastoma subgroups. Stereospecific computational analyses confirmed that group 3 and 4 tumors predominated within the midline fourth ventricle (100%, P = .007), wingless tumors were localized to the cerebellar peduncle/cerebellopontine angle cistern with a positive predictive value of 100% (95% CI, 30%–100%), and sonic hedgehog tumors arose in the cerebellar hemispheres with a positive predictive value of 100% (95% CI, 59%–100%). Midline group 4 tumors presented with minimal/no enhancement with a positive predictive value of 91% (95% CI, 59%–98%). When we used the MR imaging feature–based regression model, 66% of medulloblastomas were correctly predicted in the discovery cohort, and 65%, in the validation cohort. CONCLUSIONS: Tumor location and enhancement pattern were predictive of molecular subgroups of pediatric medulloblastoma and may potentially serve as a surrogate for genomic testing.

Less Invasive Pedicled Omental-Cranial Transposition in Pediatric Patients With Moyamoya Disease and Failed Prior Revascularization

BACKGROUND: Patients with moyamoya disease and progressive neurological deterioration despite previous revascularization pose a major treatment challenge. Many have exhausted typical sources for bypass or have ischemia in areas that are difficult to reach with an indirect pedicled flap. Omental-cranial transposition has been an effective, but sparingly used technique because of its associated morbidity. OBJECTIVE: We have refined a laparoscopic method of harvesting an omental flap that preserves its gastroepiploic arterial supply. METHODS: The pedicled omentum can be lengthened as needed by dividing it between the vascular arcades. It is transposed to the brain via skip incisions. The flap can be trimmed or stretched to cover ischemic areas of the brain. The cranial exposure is performed in parallel with pediatric surgeons. We performed this technique in 3 pediatric patients with moyamoya disease (aged 5-12 years) with previous superficial temporal artery to middle cerebral artery bypasses and progressive ischemic symptoms. In 1 patient, we transposed omentum to both hemispheres. RESULTS: Blood loss ranged from 75 to 250 mL. After surgery, patients immediately tolerated a diet and were discharged in 3 to 5 days. The ischemic symptoms of all 3 children resolved within 3 months postoperatively. Magnetic resonance imaging at 1 year showed improved perfusion and no new infarcts. Angiography showed excellent revascularization of targeted areas and patency of the donor gastroepiploic artery. CONCLUSION: Laparoscopic omental harvest for cranial-omental transposition can be performed efficiently and safely. Patients with moyamoya disease appear to tolerate this technique much better than laparotomy. With this method, we can achieve excellent angiographic revascularization and resolution of ischemic symptoms. ABBREVIATIONS: MCA, middle cerebral artery SPECT, single-photon emission computed tomography STA, superficial temporal artery TIA, transient ischemic attack

Headaches in Children with Moyamoya Disease: Does Revascularization Help?

oyamoya disease (MMD) is characterized by progressive occlusion of the internal carotid arteries or terminal M branches, accompanied by formation of extensive collateral vessels that ordinarily supply the optic nerves, pituitary gland, anterior perforated substance, dura, and other skull base structures. The appearance of these abnormal vessels resembles a cloud-like rete on angiography, which the Japanese termed moyamoya, translating to “something hazy or ill-defined.”

Tectal pineal cyst in a 1-year-old girl ☆

Glial cysts of the pineal gland can frequently be found in adults and children, but only rarely do they enlarge to become clinically relevant. We report a unique presentation of a pineal cyst in the midbrain tectum of a 16-month-old girl who initially presented with ptosis and strabismus. Preoperative imaging studies and intraoperative findings revealed no continuity between the tectal cyst and the pineal gland proper. We surmise that this tectal pineal cyst may have arisen from duplicated pineal gland tissue.