Pediatric midbrain tumors: a benign subgroup of brainstem gliomas

Tectal gliomas: assessment of malignant progression, clinical management, and quality of life in a supposedly benign neoplasm

OBJECTIVE Tectal gliomas constitute a rare and inhomogeneous group of lesions with an uncertain clinical course. Because these supposedly benign tumors are frequently followed up by observation over many years, the authors undertook this analysis of their own case series in an effort to demonstrate that the clinical course is highly variable and that there is a potential for a progressive biology. METHODS Clinical data analysis of 23 cases of tectal glioma (involving 9 children and 14 adults) was performed retrospectively. Radiographic data were analyzed longitudinally and MR images were evaluated for tumor volume, contrast enhancement, and growth progression. Quality of life was assessed using the EORTC BN20 and C30 questionnaires during follow-up in a subgroup of patients. RESULTS The patients' mean age at diagnosis was 29.2 years. The main presenting symptom at diagnosis was hydrocephalus (80%). Six patients were treated by primary tumor resection (26.1%), 3 patients underwent biopsy followed by resection (13.1%), and 3 patients underwent biopsy only (13.1%). For additional treatment of hydrocephalus, 14 patients (60.9%) received shunts and/or endoscopic third ventriculostomy. Radiographic tumor progression was observed in 47.9% of the 23 cases. The mean time between diagnosis and growth progression was 51.5 months, and the mean time to contrast enhancement was 69.7 months. Histopathological analysis was obtained in 12 cases (52.2%), resulting in 5 cases of high-grade glioma (3 cases of glioblastoma multiforme [GBM], grade IV, and 2 of anaplastic astrocytoma, grade III), 5 cases of pilocytic astrocytoma, 1 diffuse astrocytoma, and 1 ganglioglioma. Malignant progression was observed in 2 cases, with 1 case progressing from a diffuse astrocytoma (grade II) to a GBM (grade IV) within a period of 13 years. Quality-of-life measurements demonstrated distinct functional deficits compared to a healthy sample as well as glioma control cohorts. CONCLUSIONS Analysis of this case series shows that a major subpopulation of tectal gliomas show progression and malignant transformation in children as well as in adolescents. These tumors therefore cannot be considered inert lesions and require histological confirmation and close follow-up. Quality-of-life questionnaires show that tectal glioma patients might benefit from special psychological support in emotional, social, and cognitive functionality.

Tectal glioma as a distinct diagnostic entity: a comprehensive clinical, imaging, histologic and molecular analysis

Tectal glioma (TG) is a rare low-grade tumor occurring predominantly in the pediatric population. There has been no detailed analysis of molecular alterations in TG. Risk factors associated with inferior outcome and long-term sequelae of TG have not been well-documented. We retrospectively studied TGs treated or referred for review at St. Jude Children’s Research Hospital (SJCRH) between 1986 and 2013. Longitudinal clinical data were summarized, imaging and pathology specimen centrally reviewed, and tumor material analyzed with targeted molecular testing and genome-wide DNA methylation profiling. Forty-five patients with TG were included. Twenty-six (57.8%) were male. Median age at diagnosis was 9.9 years (range, 0.01–20.5). Median follow-up was 7.6 years (range, 0.5–17.0). The most common presenting symptoms were related to increased intracranial pressure. Of the 22 patients treated at SJCRH, 19 (86%) required cerebrospinal fluid diversion and seven (32%) underwent tumor-directed surgery. Five patients (23%) received radiation therapy and four (18%) systemic therapy. Ten-year overall and progression-free survival were 83.9 ± 10.4% and 48.7 ± 14.2%, respectively. Long-term morbidities included chronic headaches, visual symptoms and neurocognitive impairment. Lesion ≥3cm², contrast enhancement and cystic changes at presentation were risk factors for progression. Among those with tumor tissue available, 83% showed growth patterns similar to pilocytic astrocytoma and 17% aligned best with diffuse astrocytoma. BRAF duplication (a marker of KIAA1549-BRAF fusion) and BRAF V600E mutation were detected in 25% and 7.7%, respectively. No case had histone H3 K27M mutation. DNA methylation profile of TG was distinct from other brain tumors. In summary, TG is an indolent, chronic disease with unique clinical and molecular profiles and associated with long term morbidities. Large size, contrast enhancement and cystic changes are risk factors for progression.

A multi-institutional study of brainstem gliomas in children with neurofibromatosis type 1

OBJECTIVE

To define the clinical and radiologic features of brainstem gliomas (BSGs) in children with neurofibromatosis type 1 (NF1).

METHODS

We performed a retrospective cross-sectional study of 133 children with NF1 and concurrent BSGs cared for at 4 NF1 referral centers. BSG was determined using radiographic criteria. Age at diagnosis, tumor location and appearance, clinical symptoms, treatment, and presence of a concurrent optic pathway glioma were assessed.

RESULTS

The average age at BSG diagnosis was 7.2 years, and tumors occurred most often in the midbrain and medulla (66%). The majority of children with NF1-BSGs were asymptomatic (54%) and were not treated (88%). Only 9 of the 72 asymptomatic children received treatment because of progressive tumor enlargement. In contrast, 61 children presented with clinical signs/symptoms attributable to their BSG; these individuals were older and more often had focal lesions. Thirty-one patients underwent treatment for their tumor, and 14 received CSF diversion only. Progression-free survival was ∼3 years shorter for children receiving tumor-directed therapy relative to those who had either no treatment or CSF diversion only. Overall survival was 85% for the tumor-directed therapy group, whereas no deaths were reported in the untreated or CSF diversion groups.

CONCLUSIONS

Unlike children with sporadically occurring BSGs, most children with NF1-BSGs were asymptomatic, and few individuals died from complications of their tumor. Those requiring tumor-directed treatment tended to be older children with focal lesions, and had clinically more aggressive disease relative to those who were not treated or underwent CSF diversion only.

Posterior fossa tumors in children: developmental anatomy and diagnostic imaging

INTRODUCTION

Modern understanding of the relation between the mutated cancer stem cell and its site of origin and of its interaction with the tissue environment is enhancing the importance of developmental anatomy in the diagnostic assessment of posterior fossa tumors in children. The aim of this review is to show how MR imaging can improve on the exact identification of the tumors in the brainstem and in the vicinity of the fourth ventricle in children, using both structural imaging data and a precise topographical assessment guided by the developmental anatomy.

RESULTS

The development of the hindbrain results from complex processes of brainstem segmentation, ventro-dorsal patterning, multiple germinative zones, and diverse migration pathways of the neural progenitors. Depending on their origin in the brainstem, gliomas may be infiltrative or not, as well as overwhelmingly malignant (pons), or mostly benign (cervicomedullary, medullo-pontine tegmental, gliomas of the cerebellar peduncles). In the vicinity of the fourth ventricles, the prognosis of the medulloblastomas (MB) correlates the molecular subtyping as well as the site of origin: WNT MB develop from the Wnt-expressing lower rhombic lip and have a good prognosis; SHH MB develop from the Shh-modulated cerebellar cortex with an intermediate prognosis (dependent on age); recurrences are local mostly. The poor prognosis group 3 MB is radiologically heterogeneous: some tumors present classic features but are juxtaventricular (rather than intraventricular); others have highly malignant features with a small principal tumor and an early dissemination. Group 4 MB has classic features, but characteristically usually does not enhance; dissemination is common. Although there is as yet no clear molecular subgrouping of the ependymomas, their sites of origin and their development can be clearly categorized, as most develop in an exophytic way from the ventricular surface of the medulla in clearly specific locations: the obex region with expansion in the cistern magna, or the lateral recess region with expansion in the CPA and prepontine cisterns (cerebellar ependymomas, and still more intra-brainstem ependymomas are rare). Finally, almost all cerebellar gliomas are pilocytic astrocytomas.

CONCLUSIONS

A developmental and anatomic approach to the posterior fossa tumors in children (together with diffusion imaging data) provides a reliable pre-surgical identification of the tumor and of its aggressiveness.

Pediatric brainstem gliomas: new understanding leads to potential new treatments for two very different tumors

Pediatric brainstem gliomas include low-grade focal brainstem gliomas (FBSG) and high-grade diffuse intrinsic pontine gliomas (DIPG). These tumors share a crucial and eloquent area of the brain as their location, which carries common challenges for treatment. Otherwise, though, these two diseases are very different in terms of presentation, biology, treatment, and prognosis. FBSG usually present with greater than 3 months of symptoms, while DIPG are usually diagnosed within 3 months of symptom onset. Surgery remains the preferred initial treatment for FBSG, with chemotherapy used for persistent, recurrent, or inoperable disease; conversely, radiation is the only known effective treatment for DIPG. Recent developments in biological understanding of both tumors have led to new treatment possibilities. In FBSG, two genetic changes related to BRAF characterize the majority of tumors, and key differences in their biological effects are informing strategies for targeted chemotherapy use. In DIPG, widespread histone H3 and ACVR1 mutations have led to new hope for effective targeted treatments. FBSG has an excellent prognosis, while the long-term survival rate of DIPG tragically remains near zero. In this review, we cover the epidemiology, biology, presentation, imaging characteristics, multimodality treatment, and prognosis of FBSG and DIPG, with a focus on recent biological discoveries.

Focal brainstem gliomas. Advances in intra-operative management

Improved neuronavigation guidance as well as intraoperative imaging and neurophysiologic monitoring technologies have enhanced the ability of neurosurgeons to resect focal brainstem gliomas. In contrast, diffuse brainstem gliomas are considered to be inoperable lesions. This article is a continuation of an article that discussed brainstem glioma diagnostics, imaging, and classification. Here, we address open surgical treatment of and approaches to focal, dorsally exophytic, and cervicomedullary brainstem gliomas. Intraoperative neuronavigation, intraoperative neurophysiologic monitoring, as well as intraoperative imaging are discussed as adjunctive measures to help render these procedures safer, more acute, and closer to achieving surgical goals.

Delayed diagnosis of childhood low-grade glioma: causes, consequences, and potential solutions

PURPOSE

Diagnosis of childhood brain tumors is delayed more than diagnosis of other pediatric cancers. However, the contribution of the most common pediatric brain tumors, lowgrade gliomas (LGG), to this delay has never been investigated.

METHODS

We retrospectively reviewed cases of childhood LGG diagnosed from January 1995 through December 2005 at our institution. The pre-diagnosis symptom interval (PSI) was conservatively calculated, and its association with race, sex, age, tumor site, tumor grade, and outcome measures (survival, disease progression, shunt use, seizures, extent of resection) was analyzed. Cases of neurofibromatosis type 1 were reported separately.

RESULTS

The 258 children had a median follow-up of 11.1 years, and 226 (88 %) remained alive. Greater pre-diagnosis symptom interval (PSI) was significantly associated with grade I (vs. grade II) tumors (p = 0.03) and age >10 years at diagnosis (p = 0.03). Half of the 16 spinal tumors had a PSI > 6 months. PSI was significantly associated with progression (p = 0.02) in grade I tumors (n = 195) and in grade I tumors outside the posterior fossa (n = 134, p = 0.03). Among children with grade I tumors, median PSI was longer in those who had seizures (10.3 months) than in those who did not (2.5 months) (p = 0.09).

CONCLUSIONS

Delayed diagnosis of childhood LGG allows tumor progression. To reduce time to diagnosis, medical curricula should emphasize inclusion of LGG in the differential diagnosis of CNS neoplasm.

Gamma Knife radiosurgery for low-grade tectal gliomas

BACKGROUND

Tectal gliomas are present in a critical location that makes their surgical treatment difficult. Stereotactic radiosurgery presents an attractive noninvasive treatment option. However, tectal gliomas are also commonly associated with aqueductal obstruction and consequently hydrocephalus. This necessitates some form of CSF diversion procedure before radiosurgery. The aim of the study was to assess the efficacy and safety of Gamma Knife radiosurgery for tectal gliomas.

PATIENTS AND METHODS

Between October 2002 and May 2011, 11 patients with tectal gliomas were treated with Gamma Knife radiosurgery. Five patients had pilocytic astrocytomas and six nonpilocytic astrocytomas. Ten patients presented with hydrocephalus and underwent a CSF diversion procedure [7 V-P shunt and 3 endoscopic third ventriculostomy (ETV)]. The tumor volume ranged between 1.2-14.7 cc (median 4.5 cc). The prescription dose was 11-14 Gy (median 12 Gy).

RESULTS

Patients were followed for a median of 40 months (13-114 months). Tumor control after radiosurgery was seen in all cases. In 6/11 cases, the tumors eventually disappeared after treatment. Peritumoral edema developed in 5/11 cases at an onset of 3-6 months after treatment. Transient tumor swelling was observed in four cases. Four patients developed cysts after treatment. One of these cases required aspiration and eventually disappeared, one became smaller spontaneously, and two remained stable.

CONCLUSION

Gamma Knife radiosurgery is an effective and safe technique for treatment of tectal gliomas. Tumor shrinkage or disappearance after Gamma Knife radiosurgery may preclude the need for a shunt later on.

Clinico-radiological profile and nuances in the management of cervicomedullary junction intramedullary tumors

BACKGROUND

Cervicomedullary junction (CMJ) intramedullary tumors comprise of tumors that often pose a surgical challenge even in the present era. Though classified under brainstem glioma CMJ tumors are well amenable for surgical resection and have a good outcome. Various factors are involved in the outcome of these patients following surgery and a proper pre-operative assessment is often required to reduce the morbidity and mortality.

MATERIALS AND METHODS

Patients admitted in the Department of Neurosurgery with a diagnosis of CMJ intramedullary tumors from January 2001 to January 2010 were included in the study. Patients were analyzed retrospectively regarding their symptomatology, clinical findings, radiology and outcome after surgery. All patients underwent pre-operative magnetic resonance imaging (MRI) and post-operatively all were managed in the neurosurgery intensive care unit for days to weeks or as dictated by the clinical condition of the patient.

RESULTS

A total of 32 patients were included in the present study. The number of males was 21 (65.6%) and females were 11 (34.4%) respectively. The mean age of presentation was 22.97 ± 9.8 years and the mean duration of pre-operative symptoms was 13.3 ± 12.9 months. The tumor had extension from the CMJ into the cervical region in 17 (53.1%) and into the medullary region in 14 (43.8%) patients. Tumor decompression was done in 9 (28.1%) patients and gross near total excision done in 23 (71.87%) patients.

CONCLUSIONS

Cervicomedullary tumors are a subset of tumors quite distinct from the usual brainstem tumors. Patients having predominant cervical involvement present early and have less post-operative deficits. Those with predominantly more medullary involvement present late, hence have a much more morbid outcome. Though closely related to vital neural structures, surgery forms the mainstay of treatment. Adequate pre-operative planning and preparation of the patient along with intense post-operative monitoring and ventilatory assistance as and when required helps in a good surgical outcome.

Pediatric tectal plate gliomas: clinical and radiological progression, MR imaging characteristics, and management of hydrocephalus

OBJECT

Tectal plate gliomas are generally low-grade astrocytomas with favorable prognosis, and observation of the lesion and management of hydrocephalus remain the mainstay of treatment.

METHODS

A cohort of patients with tectal plate gliomas at 2 academic institutions was retrospectively reviewed.

RESULTS

Forty-four patients with a mean age of 10.2 years who harbored tectal plate gliomas were included in the study. The mean clinical and radiological follow-up was 7.6 ± 3.3 years (median 7.9 years, range 1.5-14.7 years) and 6.5 ± 3.1 years (median 6.5 years, range 1.1-14.7 years), respectively. The most frequent intervention was CSF diversion (81.8% of patients) followed by biopsy (11.4%), radiotherapy (4.5%), chemotherapy (4.5%), and resection (2.3%). On MR imaging tectal plate gliomas most commonly showed T1-weighted isointensity (71.4%), T2-weighted hyperintensity (88.1%), and rarely enhanced (19%). The initial mean volume was 1.6 ± 2.2 cm(3) and it increased to 2.0 ± 4.4 cm(3) (p = 0.628) at the last follow-up. Frontal and occipital horn ratio (FOHR) and third ventricular width statistically decreased over time (p < 0.001 and p < 0.05, respectively).

CONCLUSIONS

The authors' results support existing evidence that tectal plate gliomas frequently follow a benign clinical and radiographic course and rarely require any intervention beyond management of associated hydrocephalus.

Tectal plate gliomas: a review

INTRODUCTION

Tectal plate gliomas are generally benign neoplastic lesions arising in the brainstem which can, with local extension, obstruct the aqueduct of Sylvius and lead to hydrocephalus.

ANATOMY

Diagnosis is based on initial suspicion fostered by the presentation of an obstructive hydrocephalus followed by physical exam which may potentially reveal indications of pyramidal tract dysfunction or cranial nerve palsies.

DISCUSSION

MRI studies reveal a characteristic well-circumscribed, isodense or hypodense mass on T1-weighted images, with hyperdensity on T2 imaging. Yet current radiological methods insufficiently distinguish tectal plate gliomas from brainstem tumors or gliomas in the neighboring structures, and a definitive diagnosis requires biopsy and histopathological analysis. Management is planned according to the degree of associated signs and symptoms, and may range from diligent observation and periodic screening for advancing tumor development, to cerebrospinal fluid shunting in an effort to resolve obstructive hydrocephalus, to radio- and chemotherapy. A wide range of minimally invasive approaches using endoscopy is available for the neurosurgeon, including endoscopic third ventriculostomy and endoscopic aqueductoplasty.

Establishment of experimental glioma models at the intrinsic brainstem region of the rats

OBJECTIVES

As the treatment of human intrinsic brainstem gliomas remains challenging, experimental glioma models are needed.

METHODS

We developed a rat model of intrinsic brain stem glioma that uses a stereotactic frame to fix the head for the delivery of C6 glioma cells to target sites via a permanently implanted cannula. We inoculated the rat midbrain, pons or cerebral cortex with 5 x 10(4) cells suspended in 1 microl culture medium over the course of 2 minutes.

RESULTS

Three days post-implantation, tumor formation was visible in the periaqueductal gray matter in the midbrain and the tegmentum of the pons. On the tenth day, the tumor diameter exceeded over 2 mm; there was no tumor cell seeding into the cerebrospinal fluid space. The tumor manifested the histological features typical of glioblastoma; Ki-67 labeling index was 32%.

DISCUSSION

Because in our model the cannula is permanently implanted, additional inocula can be delivered. Here we detail our rat brainstem glioma model and discuss its usefulness for the investigation of these tumor in humans.

The place of interstitial brachytherapy and radiosurgery for low-grade gliomas

Even though stereotactic brachytherapy has been used for treatment of complex located low-grade glioma for many years, its place within modern treatment concepts is still debated and only a few centers have gained experience with this complex treatment modality. The current article reviews selection criteria, treatment protocols, radiobiology, treatment effects, risk models and side effects of stereotactic brachytherapy. Potentially alternative techniques such as radiosurgery were also reviewed under consideration of radiobiological similarities and differences.

6-year-old girl with hydrocephalus

With rare exceptions, pediatric tectal gliomas have been generally reported as low-grade tumors with relatively good prognosis. The patients are usually treated conservatively to manage the signs and symptoms of obstructive hydrocephalus. We report a case of a tectal glioma in a 6-years-old girl with histological features of anaplastic mixed oligoastrocytoma that continues to progress despite chemotherapy and radiation therapy.

Primary midbrain germinoma

Intracranial germinomas arising primarily in the midbrain are extremely rare and only one case has been reported in the literature. A 15-year-old boy presented with headache, diplopia, unsteadiness and personality changes. Brain MRI showed a heterogeneous lesion in the midbrain. The pineal body region was free. The preoperative diagnosis included brain-stem glioma, metastasis and lymphoma. Stereotactic biopsy was permitted in order to take a specimen and the diagnosis of germinoma was established. The patient responded well to chemotherapy and radiotherapy. Germinoma should be included in the differential diagnosis of midbrain lesions. Preoperative diagnosis is difficult and biopsy is still needed for such lesions.

Pediatric brain stem lesions: introduction of a scoring system for clinical evaluation and their treatment analysis

INTRODUCTION

Brainstem lesions in pediatric age group include mainly gliomas. As these are not usually amenable to complete surgical resection, multimodality treatments are used. To assess treatment responses, Karnofsky's Performance Score (KPS) has been the gold standard; however, in pediatric patients, comprehensive neurological examination is more valuable.

OBJECTIVE

Our purpose was to formulate neurological examination based scoring system and compare its effectiveness with KPS.

MATERIALS AND METHODS

A retrospective analysis of 37 pediatric patients with brainstem lesions was performed. All these patients were assessed both pre- and post-treatment and in every follow up using standard KPS and our proposed scoring system, Kumar's and Samir's Score (K&SS). K&SS was devised choosing the common clinical features and those affecting outcome the most. Twenty-two features were hence selected, and points were allotted to each according to their functional importance, with range from 22 to 100.

RESULTS AND DISCUSSION

Twenty-seven had gliomas, and in nonglioma group, seven had brainstem tuberculosis (BSTB). Nineteen patients with BSG were less than 6 years of age. Most gliomas were pilocytic astrocytomas (n = 21). Outcome analysis of patients in both groups using KPS showed deterioration or no change in the scores in majority whereas using K&SS, most patients showed improvement.

CONCLUSION

Gliomas form majority of pediatric brainstem lesions, with high occurrence of BSTB in nongliomatous group. Our proposed scoring system, based on comprehensive neurological examination, is more sensitive than KPS in treatment analysis of brainstem lesions.

Presentation of childhood CNS tumours: a systematic review and meta-analysis

BACKGROUND

Suspicion of a CNS tumour is classically raised by symptoms of raised intracranial pressure, focal deficits (including seizures), or papilloedema. Development of guidelines is needed for the identification and referral of children who might have a CNS tumour. We did a systematic literature review and meta-analysis to identify the clinical presentation of childhood CNS tumours to provide evidence to support the development of guidelines to assist with the identification and referral for imaging of children who might have a central nervous system tumour.

METHODS

Medline, Embase, and PubMed were searched for cohort studies and case series in children, published between January, 1991, and August, 2005, detailing the symptoms and signs at diagnosis of a CNS tumour.

FINDINGS

74 papers (n=4171) met the inclusion criteria. 56 symptoms and signs at diagnosis were identified, ranked by frequency, and clustered according to age, anatomical criteria, and genetic criteria. The most frequent symptoms and signs at diagnosis were: headache (33%), nausea and vomiting (32%), abnormalities of gait and coordination (27%), and papilloedema (13%) for intracranial tumours; macrocephaly (41%), nausea and vomiting (30%), irritability (24%), and lethargy (21%) for children aged under 4 years with intracranial tumours; reduced visual acuity (41%), exophthalmia (16%), and optic atrophy (15%) for children with an intracranial tumour and neurofibromatosis; nausea and vomiting (75%), headache (67%), abnormal gait and coordination (60%), and papilloedema (34%) for posterior fossa tumours; unspecified symptoms and signs of raised intracranial pressure (47%), seizures (38%), and papilloedema (21%) for supratentorial tumours; headache (49%), abnormal eye movements (21%), squint (21%), and nausea and vomiting (19%) for central brain tumours; abnormal gait and coordination (78%), cranial nerve palsies (52%), pyramidal signs (33%), headache (23%), and squint (19%) for brainstem tumours; and back pain (67%), abnormalities of gait and coordination (42%), spinal deformity (39%), focal weakness (21%), and sphincter disturbance (20%) for spinal-cord tumours. Other features noted were weight loss, growth failure, and precocious puberty. Symptoms of raised intracranial pressure were absent in more than half of children with brain tumours. Other neurological features were heterogeneous and related to tumour location.

INTERPRETATION

Apart from raised intracranial pressure, motor and visual system abnormalities, weight loss, macrocephaly, growth failure, and precocious puberty also suggest presence of an intracranial tumour. Children with signs and symptoms that could result from a CNS tumour need a thorough visual and motor system examination and an assessment of growth and pubertal status. Occurrence of multiple symptoms and signs should alert clinicians to possible CNS tumours.

Gamma Knife surgery for focal brainstem gliomas

Object

Focal tumors, a distinct subgroup of which is composed of brainstem gliomas, may have an indolent clinical course. In the past, their management involved monitoring of open-ended imaging studies and shunt placement if cerebrospinal fluid diversion was required. Nonetheless, their treatment remains a significant challenge for neurosurgeons. Gamma Knife surgery (GKS) has recently been tried as an alternative to surgical extirpation. In the present study the authors assess clinical and imaging results in 20 patients who harbored focal brainstem gliomas treated with GKS between 1990 and 2001.

Methods

There were 10 male and 10 female patients with a mean age of 19.1 years. Sixteen tumors were located in the midbrain, three in the pons, and one in the medulla oblongata. The mean tumor volume at the time of GKS was 2.5 cm3. In 10 cases a tumor specimen was obtained either by open surgery or stereotactic biopsy, securing the diagnosis of pilocytic astrocytoma in five patients and nonpilocytic astrocytoma in five others. In the remaining 10 cases, the diagnosis was based on clinical and neuroimaging findings. The prescription Gamma Knife dose varied between 10 and 18 Gy, except in three patients who were receiving a boost to a site in which external-beam radiation was previously delivered. An average of four isocenters were utilized per GKS.

Patients were followed up for a mean of 78.0 months. The tumors disappeared in four patients and shrank in 12 patients. Of these patients, one experienced transitory extrapyramidal symptoms and fluctuating impairment of consciousness (from somnolence to coma) for 6 months. Another patient whose tumor disappeared 3 years following GKS died of stroke 8 years postoperatively. The rest of the patients either remained stable or improved clinically. Tumor progression occurred in four patients; of these four, one patient developed hydrocephalus requiring a ventriculoperitoneal shunt, two showed neurological deterioration, and one 4-year-old boy died of tumor progression.

Conclusions

Gamma Knife surgery may be an effective primary treatment or adjunct to open surgery for focal brainstem gliomas.

Tectal plate lesions in children

OBJECT

The authors characterized the clinical course of tectal plate lesions in a group of pediatric patients to identify the prognostic factors at presentation that predict progression, in an attempt to differentiate tectal hamartomas from tumors.

METHODS

A retrospective review was conducted of the management of tectal plate lesions in children since the advent of magnetic resonance (MR) imaging at the authors' hospital (1984-2003). The lesion volume seen on MR images, the clinical and radiological features at presentation, and the clinical course of the population were analyzed for correlations. Forty children with tectal lesions presented in the typical delayed fashion (mean 8.5 months) with symptoms referable to hydrocephalus (93%). Fourteen children whose tumors demonstrated radiological progression (enlargement, contrast enhancement, or cystic change) were treated surgically. Histologically, 80% of the surgically treated lesions were low grade (with the other 20% consisting of one dysplasia, one high-grade tumor, and one unidentified tumor). Five patients required a second operation and one required a third. One patient died of a high-grade astrocytoma after undergoing surgery and radiotherapy; the other 39 patients remain clinically stable. The only factor predictive of tumor enlargement was lesion volume at presentation (p = 0.002). Distribution analysis revealed three subgroups based on lesion volume (< 4, 4-10, and > 10 cm3), which correlated with the clinical course of the disease.

CONCLUSIONS

Children with tectal lesions should undergo contrast-enhanced MR imaging and volume assessment at the time of presentation. After hydrocephalus has been managed with endoscopic third ventriculostomy, these children require prolonged, close clinical and radiological surveillance. Lesions with a volume less than 4 cm3 were likely to be hamartomas and followed a predominantly benign course, with few atypical cases progressing. All large lesions, defined as having a volume greater than 10 cm3 at presentation, eventually required treatment, and all were histologically determined to be tumors. An argument is made for earlier treatment of larger lesions with the aim of improving outcome.

Tectal plate tumors

Tectal plate is a rare location for a tumor. Many papers have described different types of pathology arising in that location including tumors, vascular lesions, inflamatory and infectious processes. In this paper we describe our experience in treating seven patients with tectal plate lesions, with different ages and types of pathology: five patients presented with low grade gliomas, one with lung cancer metastasis and the last presenting with a tectal plate cavernoma. Open surgery was performed in three cases (due to tumor enlargement or need for the exact diagnosis). In the other cases, the treatment of non-comunicating hydrocephalus was the only treatment employed. The prognosis is of course dependent on the underlining pathology. In our series, except in the metastatic tumor case and the cavernoma, the other types of lesion consisted of low grade gliomas. These lesions represent a different type of brain stem tumor sharing a common good prognosis, with a benign behavior. We believe that tectal tumors must be managed case by case. When a patient presents with a benign lesions in the tectal region, treating the main symptom - hydrocephalus - should be the first attempt in management of these lesions.

Treatment options in childhood pontine gliomas

BACKGROUND

Pontine gliomas are the subgroup of brainstem gliomas with the worst prognosis. Controversial treatment approaches are discussed.

PATIENTS AND METHODS

Data of children with pontine gliomas treated in different prospective multi-center studies who were registered in the HIT-GBM database were pooled and analyzed addressing prognostic factors and the relevance of intensive treatment using contingency tables, Kaplan-Meier curves and Cox regression analyses.

RESULTS

From 1983 to 2001, 153 patients (74 males, 79 females, mean age: 8.1 years) with pontine gliomas were registered. Twenty-one tumors were low-grade and 60 were high-grade gliomas (72 undefined histology: 67 no surgery, 5 incomplete data). Sixteen tumors were partially resected, and 125 were irradiated. Ninety children received chemotherapy according to the "HIT-GBM" protocols ("Hirntumor-Glioblastoma multiforme"). The one-year overall survival rate (1YOS) of all patients with pontine glioma was 39.9+/-4.3%. None of the surviving patients had an observation time longer than 3.9 years. Favorable prognostic factors seemed to be age younger than 4 years, low-grade histology and smaller tumor. All three major treatment modalities including resection, irradiation and chemotherapy had prognostic relevance in univariable analysis. Chemotherapy remained beneficial, even if the analysis was restricted to the subgroup of irradiated tumors (1YOS 45.8+/-5.4% vs. 34.4+/-13.5%, P=0.030).

CONCLUSION

Irradiation is an effective element for the treatment of pontine gliomas. Intensive chemotherapy seems to be important in achieving a better OS.

Excision of juvenile pilocytic astrocytoma of the midbrain after radiotherapy

A 13-year-old girl presented with consciousness disturbance, right hemiparesis, and impairment of hearing, swallowing, and ocular movements. A magnetic resonance image demonstrated marked hydrocephalus due to a large cystic tumor (40 x 40 x 30 mm) in the midbrain. Emergency ventricular drainage and stereotactic cyst puncture dramatically improved her condition. Since her family did not agree to surgery on the brain stem, radiotherapy was performed after ventriculoperitoneal shunting. Conventional radiotherapy of 50.4 Gy was temporarily effective, and the growth of the tumor was stabilized until approximately 8 months later when regrowth was noticed. At this stage, with the consent of her family, the tumor was removed via an infratentorial supracerebellar approach. The pathological diagnosis was juvenile pilocytic astrocytoma. The postoperative course was uneventful. No recurrence has been observed during the follow-up period of more than 6 years. This case study shows that initial excision may be appropriate for some low-grade focal lesions in the midbrain when the histological diagnosis and consent have been obtained.

Management of tectal glioma in childhood

Tectal glioma is a topographical diagnosis including tumors of different histology, mainly low-grade astrocytomas. Clinical symptoms are usually associated with increased intracranial pressure. This report discusses the management of this rare tumor in children. Clinical charts of 12 children with tectal glioma treated in our department between 1976 and 2001 were retrospectively reviewed. The mean age at the time of diagnosis was 6.75 years (range, 4 weeks to 16 years). The duration between first symptoms and the diagnosis of tectal glioma was in the range of 2 days to 9 years. Ten patients presented with symptoms associated with increased intracranial pressure, one patient presented with ataxia, and in one case tectal glioma was an incidental finding. First-line therapy was endoscopic third ventriculostomy in 5 cases (42%), ventriculoperitoneal shunting in 6 cases (50%), and combined partial tumor resection and shunting in one case. Histology was obtained in 5 cases (low-grade astrocytoma, n = 4; ependymoma, n = 1). All patients had good neurologic function at the end of follow-up. Tectal glioma represents a distinct subgroup of brainstem tumors associated with a good (or favorable) prognosis. Effective treatment for hydrocephalus is essential; the tumor should be monitored by regular clinical examination and magnetic resonance imaging. Biopsy is warranted in cases with tumor progression.

Intrinsic tectal low grade astrocytomas: is surgical removal an alternative treatment? Long-term outcome of eight cases

Low-grade gliomas arising in dorsal midbrain in children and young patients usually present few neurological symptoms and findings, and patients´ management is controversial. Some authors propose only clinical observation until the patient present signs of increased intracranial pressure when a shunt with or without biopsy, is inserted; others recommend radiotherapy after stereotactic or open biopsy. Microsurgical total removal of tumor may be curative. We present a retrospective analysis of eight patients (mean age 16.6 ±11.5 years-old) with low-grade astrocytoma of the tectal region operated on using an infratentorial/ supracerebellar approach between 1981 and 2002. All patients presented hydrocephalus and had a shunt insertion before surgical resection of the lesion. The tumour could be totally resected in seven patients. In one case radical removal was not possible due to infiltrative pattern of the lesion. Postoperative radiotherapy was performed in two cases, one patient at the beginning of this series and in the case with infiltrative tumor. This patient presented progressive tumor growth and died five years after surgery. No recurrence occurred after total removal. Post-surgical follow-up time ranged from 2 1/2 to 22 1/2 years (mean 9.9 ± 5.9 years). Radical microsurgical removal of non invasive tumors is possible without mortality or significant morbidity. It may be curative and should remain as an alternative to be discussed with the patient.

Neurosurgical treatment of brain tumors in children

Primary brain tumors are the most common solid neoplasms of childhood. The diagnosis of brain tumors in the general pediatric population remains challenging. Nevertheless, it is clear that refinements in imaging, surgical technique, and adjunctive therapies have led to longer survival and an improving quality of life in children with brain tumors.

Temozolomide in malignant gliomas of childhood: a United Kingdom Children's Cancer Study Group and French Society for Pediatric Oncology Intergroup Study

PURPOSE

To determine the response rate of the malignant gliomas of childhood to an oral, daily schedule of temozolomide.

PATIENTS AND METHODS

A multicenter, phase II evaluation of an oral, daily schedule of temozolomide (200 mg/m(2) on 5 consecutive days) was undertaken in children with relapsed or progressive, biopsy-proven, high-grade glioma (arm A) and progressive, diffuse, intrinsic brainstem glioma (arm B). Evidence of activity was defined by radiologic evidence of a sustained reduction in tumor size on serial magnetic resonance imaging scans.

RESULTS

Fifty-five patients were recruited (34 to arm A and 21 to arm B) and received 215 cycles of chemotherapy. Grade 3/4 thrombocytopenia was the most frequent toxic event (7% of cycles). Prolonged myelosuppression resulted in significant treatment delays and dose reductions (17% and 22% of cycles, respectively). Two toxic deaths were documented and were related to myelosuppression and sepsis in one patient and pneumonia in a second. The overall (best) response rate was 12% for arm A (95% confidence interval [CI], 3 to 28 in the study cohort, and 2 to 31 for eligible patients) and 5% and 6%, respectively, for arm B (95% CI, 0 to 26 in the study cohort, and 0 to 27 for eligible patients). Stabilization of disease was also documented and was most noteworthy for brainstem gliomas, where two patients achieved both radiologic static disease and discontinued steroid medication.

CONCLUSION

Despite moderate toxicity, objective response rates to temozolomide have been low, indicating that temozolomide has minimal activity in the high-grade gliomas of childhood.

Long-term control of hydrocephalus via endoscopic third ventriculostomy in children with tectal plate gliomas

OBJECTIVE

We report the control of hydrocephalus in children with presumed tectal plate gliomas by the use of endoscopic third ventriculostomy (ETV).

METHODS

The hospital records, office charts, and imaging studies from children who underwent ETV at the Children's Hospital of Alabama were reviewed. Thirteen children with the diagnosis of tectal plate glioma and hydrocephalus were identified. ETV was the primary therapy instituted for all but one of these children. Successful treatment outcome was defined as shunt freedom, improvement in symptoms, and reduced ventricular size.

RESULTS

Thirteen children underwent a total of 15 ETVs, and all children were shunt-free at their most recent follow-up examinations. One child underwent successful secondary ETV, one child underwent shunt removal concomitant with the initial ETV, and one child underwent shunt removal concomitant with secondary ETV. Symptoms and signs resolved in all patients. All postoperative cranial imaging studies revealed normal or reduced ventricular size as compared with preoperative cranial imaging scans. The median follow-up period was 31 months.

CONCLUSION

In our surgical experience, ETV has been uniformly successful in the management of hydrocephalus caused by tectal plate gliomas in children. ETV should be considered the treatment of choice for hydrocephalus in pediatric patients with tectal plate gliomas.

A clinicopathologic reappraisal of brain stem tumor classification. Identification of pilocystic astrocytoma and fibrillary astrocytoma as distinct entities

BACKGROUND

Brain stem tumors in children have been classified pathologically as low grade or high grade gliomas and descriptively as diffuse gliomas, intrinsic gliomas, midbrain tumors, tectal gliomas, pencil gliomas, dorsal exophytic brain stem tumors, pontine gliomas, focal medullary tumors, cervicomedullary tumors, focal gliomas, or cystic gliomas.

METHODS

To search for a simplified and prognostic clinicopathologic scheme for brain stem tumors, the authors reviewed a consecutive cohort of patients younger than age 21 years with tumors diagnosed from 1980 through 1997. Pathology specimens and neuroimaging were classified by masked review. Statistical and survival analysis along with Cox proportional hazards regression was performed.

RESULTS

Seventy-six patients were identified, with initial diagnostic magnetic resonance imaging available for 51 and pathology specimens for 48 patients. Twenty cases were classified histologically as pilocytic astrocytoma (PA), 14 as fibrillary astrocytoma (FA), and 14 as other tumors or indeterminate pathology. For all tumors, characteristics significantly associated with a worse survival rate were: symptom duration less than 6 months before diagnosis (P = 0.004); abducens palsy at presentation (P < 0.0001); pontine location (P = 0.0002); and engulfment of the basilar artery (P = 0.006). Pilocytic astrocytoma was associated with location outside the ventral pons (P = 0.001) and dorsal exophytic growth (P = 0.013); Fibrillary astrocytoma was associated with symptoms less than 6 months (P = 0. 006), abducens palsy (P < 0.001), and engulfment of the basilar artery (P = 0.002). Pilocytic astrocytoma showed 5-year overall survival (OS) of 95% (standard error [SE], 5%) compared with FA 1-year OS of 23% (SE, 11%;P < 0.0001).

CONCLUSIONS

Brain stem tumors can be succinctly and better biologically classified as diffusely infiltrative brain stem gliomas-generally FA located in the ventral pons that present with abducens palsy, often engulf the basilar artery, and carry a grim prognosis-and focal brain stem gliomas-frequently PA arising outside the ventral pons, often with dorsal exophytic growth, a long clinical prodrome, and outstanding prognosis for survival. Our findings emphasize the individuality of PA as a distinct clinicopathologic entity with an exceptional prognosis.

Radiotherapy followed by high dose busulfan and thiotepa: a prospective assessment of high dose chemotherapy in children with diffuse pontine gliomas

BACKGROUND

The role of high dose chemotherapy (HDC) in patients with pediatric brain tumors currently is ill-defined. The purpose of this pilot study was to assess the feasibility and the benefit of HDC after radiotherapy in a group of children with newly diagnosed diffuse pontine gliomas.

METHODS

Patients eligible for study were ages 3-18 years with diffuse intrinsic tumors arising in the pons, who were not treated previously with radiotherapy or chemotherapy. Histologic confirmation was not mandatory, provided clinical findings and magnetic resonance imaging were typical. Patients were given focal radiotherapy followed 2-3 months later by HDC. Busulfan (150 mg/m(2) on Days 8, 7, 6, and 5) and thiotepa (300 mg/m(2) on Days 4, 3, and 2) were administered prior to autologous bone marrow transplantation. Survival was the endpoint, and the statistical procedure was based on sequential subgroup analysis.

RESULTS

Thirty-six patients were entered on to the study, 12 of whom underwent stereotactic biopsy or open surgery at the time of diagnosis. One patient eventually was excluded due to inappropriate eligibility criteria. All 35 eligible patients received irradiation. Early progression (9 patients) and parental refusal (2 patients) precluded the use of HDC in 11 patients. Three patients died of HDC-related complications. All 21 patients who survived HDC eventually died of disease progression. The median survival time was 10 months for the study group. The median survival time in the subgroup of patients who received HDC was 10 months (range, 3-26 months). Statistical analysis did not suggest any evidence of survival benefit.

CONCLUSIONS

For patients with diffuse pontine gliomas, survival using this aggressive treatment modality does not appear to be any better than that reported for conventional radiotherapy.

Surgical treatment of primary midbrain gliomas

BACKGROUND

The treatment of brainstem gliomas remains controversial. This article focuses on surgical results.

METHODS

The authors retrospectively analyzed 35 patients with primary midbrain gliomas who were treated at Beijing Neurosurgical Institute from 1986 to 1997. The diagnosis was verified by histological examination.

RESULT

The incidence of midbrain glioma was 10.3% (35/340) in our patients with brain stem tumors. The 35 gliomas were classified into three therapeutic groups by their locations: 7 were located in the tectal region, 8 in the aqueductal region, and 20 in the tegmental region. All of the patients underwent microsurgical treatment based on a minimally invasive approach. The operation took the form of total resection in 19 cases, subtotal resection in 12, and partial resection in 4. The operative mortality was 0. With a mean follow-up of 28 months (range, 6-48 months), 65.7% (23/35) of patients could live independently.

CONCLUSION

The volume and location of midbrain tumors were highly correlated with outcome. The resection of as much tumor as possible was optimal for the treatment of midbrain gliomas and radiotherapy after operation was beneficial to patients.

The results of radiotherapy for brainstem tumors

OBJECTIVE

This analysis was performed to examine the outcome of adult and pediatric patients with brainstem tumors.

METHODS AND MATERIALS

Forty patients with brainstem glioma were evaluated retrospectively. Included were 24 females and 16 males ranging in age from 3 to 81 years (median, 29.5 years). These patients were treated with various combinations of surgery, chemotherapy, and radiotherapy (RT). The length of follow-up in survivors ranged from 0.6 to 20 years (median: 3.2 years, mean: 6 years). Survival rates were calculated with the Kaplan Meier method and differences between survival curves were calculated using the log-rank test.

RESULTS

The overall 2 and 5-year survival rates were 44% and 34%, respectively. The median survival time was 19 months. The 5-year survival rate was 54% for patients with tumors outside the pons compared to 21% for those with tumors involving the pons (p = 0.04). The 5-year survival rate was 59% for patients with exophytic tumors as compared to 23% for those with intrinsic tumors (p = 0.05). Patients undergoing subtotal resection had a 5-year survival rate of 53% compared to 28% for those having only a biopsy or no surgical intervention (p = 0.04). None of the other potential prognostic or treatment related factors evaluated [patient age, tumor grade, tumor histology, radiotherapy parameters (including BID fractionation, 3-D treatment planning, or the use of doses > 55 Gy), or the administration of adjuvant chemotherapy] evaluated were associated with patient survival.

CONCLUSIONS

Brainstem gliomas generally occur in younger individuals. The survival rates were better for patients with exophytic tumors, those involving sites other than the pons, and tumors amenable to subtotal resection. Improvements in the outcome of patients with brainstem gliomas will require new therapeutic approaches.

Low-grade astrocytomas in children: evolving management strategies

Developments in imaging and in neurosurgical techniques over the past decade have substantially altered the management of children with low-grade astrocytoma. Indications for surgery have become more clearly defined, and a larger proportion of children undergo complete or subtotal resection than in the past. Fewer receive adjuvant therapy, even though the options in this regard are more numerous now and theoretically likely to result in less morbidity than conventional external beam radiotherapy. This review will address in particular the correlations between location, imaging appearance, and behavior that need to be more widely appreciated, and present recommendations regarding the management of these tumors.

Pediatric brain tumors

Brain tumors are the most common solid neoplasms in childhood. This article reviews the current classification, clinical presentations, diagnostic procedures, and principles of treatment of pediatric brain tumors. The specific presentation, treatment, and prognosis of the most common, individual types of pediatric brain tumors are discussed.

Pediatric brain stem gliomas: a review

Tumors arising in the brain stem, comprising the midbrain, pons, and medulla oblongata, are now recognized as distinct clinico-pathological entities. Advances in neurosurgical techniques have made surgery not only feasible but the treatment of choice for some of these tumor types. Previously the mainstay of treatment, radiotherapy is now used more selectively. This article reviews the current state of knowledge with regard to tumors arising in the brain stem, the therapeutic options available for each, and provides recommendations with regard to management.