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R. Michael Scott

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Mei Hua Li, Eric Bouffet, Cynthia E. Hawkins, Jeremy A. Squire, and Annie Huang

The supratentorial primitive neuroectodermal tumors (PNETs) are a group of highly malignant lesions primarily affecting young children. Although these tumors are histologically indistinguishable from infratentorial medulloblastoma, they often respond poorly to medulloblastoma-specific therapy. Indeed, existing molecular genetic studies indicate that supratentorial PNETs have transcriptional and cytogenetic profiles that are different from those of medullo-blastomas, thus pointing to unique biological derivation for the supratentorial PNET. Due to the rarity of these tumors and disagreement about their histopathological diagnoses, very little is known about the molecular characteristics of the supratentorial PNET. Clearly, future concerted efforts to characterize the molecular features of these rare tumors will be necessary for development of more effective supratentorial PNET treatment protocols and appropriate disease models. In this article the authors review existing molecular genetic data derived from human and mouse studies, with the aim of providing some insight into the putative histogenesis of these rare tumors and the underlying transforming pathways that drive their development. Studies of the related but distinct pineoblastoma PNET are also reviewed.

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John W. Rutland, Francesco Padormo, Cindi K. Yim, Amy Yao, Annie Arrighi-Allisan, Kuang-Han Huang, Hung-Mo Lin, James Chelnis, Bradley N. Delman, Raj K. Shrivastava, and Priti Balchandani

OBJECTIVE

The objective of this study was to investigate microstructural damage caused by pituitary macroadenomas by performing probabilistic tractography of the optic tracts and radiations using 7-T diffusion-weighted MRI (DWI). These imaging findings were correlated with neuro-ophthalmological results to assess the utility of ultra–high-field MRI for objective evaluation of damage to the anterior and posterior visual pathways.

METHODS

Probabilistic tractography employing 7-T DWI was used to reconstruct the optic tracts and radiations in 18 patients with adenomas and in 16 healthy volunteers. Optic chiasm compression was found in 66.7% of the patients and visual defects in 61.1%. Diffusion indices were calculated along the projections and correlated with tumor volumes and results from neuro-ophthalmological examinations. Primary visual cortical thicknesses were also assessed.

RESULTS

Fractional anisotropy was reduced by 21.9% in the optic tracts (p < 0.001) and 17.7% in the optic radiations (p < 0.001) in patients with adenomas. Patients showed an 8.5% increase in mean diffusivity of optic radiations compared with healthy controls (p < 0.001). Primary visual cortical thickness was reduced in adenoma patients. Diffusion indices of the visual pathway showed significant correlations with neuro-ophthalmological examination findings.

CONCLUSIONS

Imaging-based quantification of secondary neuronal damage from adenomas strongly correlated with neuro-ophthalmological findings. Diffusion characteristics enabled by ultra–high-field DWI may allow preoperative characterization of visual pathway damage in patients with chiasmatic compression and may inform prognosis for vision recoverability.

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Lucie Lafay-Cousin, Ute Bartels, Charles Raybaud, Abhaya V. Kulkarni, Sharon Guger, Annie Huang, and Eric Bouffet

✓Intracystic bleomycin therapy has been proposed as a treatment for predominantly cystic craniopharyngioma. The risks of using this therapy, however, have not been clearly identified. The authors report on three children treated with intracystic bleomycin who developed initially mild symptoms during their course of therapy. They describe the neuroimaging findings from computed tomography (CT) scans and magnetic resonance (MR) images and the medical management of these three cases.

Two patients in whom craniopharyngioma was recently diagnosed and one patient with recurrent craniopharyngioma were treated with a course of 3 mg of intracystic bleomycin three times a week for 5 weeks, followed by once every week for 10 weeks. All patients had a negative reservoir permeability test prior to beginning intracystic bleomycin therapy. Patients were asymptomatic or had mild symptoms at the time of neuroimaging.

Magnetic resonance images revealed extensive vasogenic edema surrounding the cyst in all three patients, consistent with signs of bleomycin leakage. The edema occurred near the time of the 12th injection in two patients, and at the end of treatment in the remaining patient. Subsequently, two patients developed further symptoms suggestive of hypothalamic injury. These two patients received corticosteroids, leading to a rapid and sustained clinical improvement. Follow-up serial MR images showed a progressive regression of the surrounding edema.

Neuroimaging documentation of bleomycin toxicity has been described mainly in adults experiencing severe toxicity. There was no correlation between clinical symptoms and the extent of edema in these three patients. An MR image provides a higher resolution than CT scans for evaluating the adjacent cerebral structures and is very sensitive in detecting early abnormalities, even in asymptomatic patients. Bleomycin therapy requires close clinical monitoring. Imaging evaluation should be performed using MR imaging during treatment to ensure the safety of the therapy. In the authors' experience, the toxicity to bleomycin was transient. Management of the toxicity using high-dose steroid administration appears to contribute to controlling the bleomycin-induced inflammatory process.

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Adriana Fonseca, Palma Solano, Vijay Ramaswamy, Uri Tabori, Annie Huang, James M. Drake, Derek S. Tsang, Normand Laperriere, Ute Bartels, Abhaya V. Kulkarni, and Eric Bouffet

OBJECTIVE

There is no consensus on the optimal clinical management of ventriculomegaly and hydrocephalus in patients with diffuse intrinsic pontine glioma (DIPG). To date, the impact on survival in patients with ventriculomegaly and CSF diversion for hydrocephalus in this population remains to be elucidated. Herein, the authors describe their institutional experience.

METHODS

Patients diagnosed with DIPG and treated with up-front radiation therapy (RT) at The Hospital for Sick Children between 2000 and 2019 were identified. Images at diagnosis and progression were used to determine the frontal/occipital horn ratio (FOR) as a method to measure ventricular size. Patients with ventriculomegaly (FOR ≥ 0.36) were stratified according to the presence of symptoms and categorized as follows: 1) asymptomatic ventriculomegaly and 2) symptomatic hydrocephalus. For patients with ventriculomegaly who did not require CSF diversion, post-RT imaging was also evaluated to assess changes in the FOR after RT. Proportional hazards analyses were used to identify clinical and treatment factors correlated with survival. The Kaplan-Meier method was used to perform survival estimates, and the log-rank method was used to identify survival differences between groups.

RESULTS

Eighty-two patients met the inclusion criteria. At diagnosis, 28% (n = 23) of patients presented with ventriculomegaly, including 8 patients who had symptomatic hydrocephalus and underwent CSF diversion. A ventriculoperitoneal shunt was placed in the majority of patients (6/8). Fifteen asymptomatic patients were managed without CSF diversion. Six patients had resolution of ventriculomegaly after RT. Of 66 patients with imaging at the time of progression, 36 (55%) had ventriculomegaly, and 9 of them required CSF diversion. The presence of ventriculomegaly at diagnosis did not correlate with survival on univariate analysis. However, patients with symptomatic hydrocephalus at the time of progression who underwent CSF diversion had a survival advantage (p = 0.0340) when compared to patients with ventriculomegaly managed with conservative approaches.

CONCLUSIONS

Although ventriculomegaly can be present in up to 55% of patients with DIPG, the majority of patients present with asymptomatic ventriculomegaly and do not require surgical interventions. In some cases ventriculomegaly improved after medical management with steroids and RT. CSF diversion for hydrocephalus at the time of diagnosis does not impact survival. In contrast, our results suggest a survival advantage in patients who undergo CSF diversion for hydrocephalus at the time of progression, albeit that advantage is likely to be confounded by biological and individual patient factors. Further research in this area is needed to understand the best timing and type of interventions in this population.

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Sheng-Huang Lin, Tsung-Ying Chen, Shinn-Zong Lin, Ming-Hwang Shyr, Yu-Cheng Chou, Wanhua Annie Hsieh, Sheng-Tzung Tsai, and Shin-Yuan Chen

Object

The authors of this preliminary study investigated the outcome and feasibility of intraoperative microelectrode recording (MER) in patients with Parkinson disease (PD) undergoing deep brain stimulation of the subthalamic nucleus (STN) after anesthetic inhalation.

Methods

The authors conducted a retrospective analysis of 10 patients with PD who received a desflurane anesthetic during bilateral STN electrode implantation. The MERs were obtained as an intraoperative guide for final electrode implantation and the data were analyzed offline. The functional target coordinates of the electrodes were compared preoperatively with estimated target coordinates.

Results

Outcomes were evaluated using the Unified Parkinson's Disease Rating Scale 6 months after surgery. The mean improvement in total and motor Unified Parkinson's Disease Rating Scale scores was 54.27 ± 17.96% and 48.85 ± 16.97%, respectively. The mean STN neuronal firing rate was 29.7 ± 14.6 Hz. Typical neuronal firing patterns of the STN and substantia pars nigra reticulata were observed in each patient during surgery. Comparing the functional target coordinates, the z axis coordinates were noted to be significantly different between the pre- and postoperative coordinates.

Conclusions

The authors found that MER can be adequately performed while the patient receives a desflurane anesthetic, and the results can serve as a guide for STN electrode implantation. This may be a good alternative surgical method in patients with PD who are unable to tolerate deep brain stimulation surgery with local anesthesia.

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Niketa C. Shah, Amit Ray, Ute Bartels, James Rutka, Eric Bouffet, James Drake, Cynthia E. Hawkins, and Annie Huang

✓ The authors report on 2 newborn infants with the unusual presentation of intrinsic brainstem tumors. Both nondysmorphic, full-term neonates had cranial nerve palsies and hypotonia. Diagnoses of diffuse intrinsic brainstem gliomas were made on the basis of magnetic resonance imaging, which showed large expansive, nonenhancing intrinsic pontine masses. Intrinsic pontine tumors, characteristically seen in school-age children, are most often high-grade gliomas that are almost invariably fatal. However, the microanatomy and natural history of pontine tumors in neonates are unknown. With parental consent, both newborns were treated expectantly with supportive care but died of progressive disease by 2 weeks of age. In one child, postmortem examination revealed a primary brainstem primitive neuroectodermal tumor. The authors conclude that, as in older children, neonatal intrinsic brainstem tumors may be of a highly malignant nature. The rapid tumor progression in both cases indicates that where a diagnostic procedure may pose significant risks, supportive observation can aid in distinguishing malignant from benign tumor growth.

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Katrin Scheinemann, Ute Bartels, Annie Huang, Cynthia Hawkins, Abhaya V. Kulkarni, Eric Bouffet, and Uri Tabori

Object

Intramedullary spinal cord low-grade gliomas (LGGs) are rare CNS neoplasms in pediatric patients, and there is little information on therapy for and outcome of these tumors in this population. Furthermore, most patient series combine adult and pediatric patients or high- and low-grade tumors, resulting in controversial data regarding optimal treatment of these children. To clarify these issues, the authors performed a regional population-based study of spinal cord LGGs in pediatric patients.

Methods

All pediatric patients with LGGs treated during the MR imaging era (1985–2007) were identified in the comprehensive database of the Hospital for Sick Children in Toronto. Data on demographics, pathology, treatment details, and outcomes were collected.

Results

Spinal cord LGGs in pediatric patients constituted 29 (4.6%) of 635 LGGs. Epidemiological and clinical data in this cohort were different than in patients with other spinal tumors and strikingly similar to data from pediatric patients with intracranial LGGs. The authors observed an age peak at 2 years and a male predominance in patients with these tumors. Histological testing revealed a Grade I astrocytoma in 86% of tumors. Although 5-year progression-free survival for the entire group was 48 ± 9%, all patients were alive at a median follow-up of 8.2 years. Five-year progression-free survival was 88 ± 13% for patients undergoing gross-total resection and 34 ± 11% for those undergoing all other therapies, respectively (p = 0.02). Chemotherapy and radiation therapy showed similar efficacy, achieving sustained tumor control in most patients. However, this excellent survival rate was associated with an 83% rate of significant neurological and orthopedic sequelae.

Conclusions

This study provides basic data on the incidence, clinical course, and outcome of spinal cord LGGs in pediatric patients. The similarities between spinal and intracranial LGGs in pediatric patients showing excellent survival but high morbidity suggest that a less aggressive approach may be the preferable treatment option for these patients.