Surgical treatment of brain stem gliomas

The brainstem and its neurosurgical history

Brainstem is one of the most complex structures of the human body, and has the most complex intracranial anatomy, which makes surgery at this level the most difficult. Due to its hidden position, the brainstem became known later by anatomists, and moreover, brainstem surgery cannot be understood without knowing the evolution of ideas in neuroanatomy, neuropathology, and neuroscience. Starting from the first attempts at identifying brainstem anatomy in prehistory and antiquity, the history of brainstem discoveries and approach may be divided into four periods: macroscopic anatomy, microscopic anatomy and neurophysiology, posterior fossa surgery, and brainstem surgery. From the first trepanning of the posterior fossa and later finger surgery, to the occurrence of safe entry zones, this paper aims to review how neuroanatomy and brainstem surgery were understood historically, and how the surgical technique evolved from Galen of Pergamon up to the twenty-first century.

Surgical approaches for the lateral mesencephalic sulcus

OBJECTIVE

The brainstem is a compact, delicate structure. The surgeon must have good anatomical knowledge of the safe entry points to safely resect intrinsic lesions. Lesions located at the lateral midbrain surface are better approached through the lateral mesencephalic sulcus (LMS). The goal of this study was to compare the surgical exposure to the LMS provided by the subtemporal (ST) approach and the paramedian and extreme-lateral variants of the supracerebellar infratentorial (SCIT) approach.

METHODS

These 3 approaches were used in 10 cadaveric heads. The authors performed measurements of predetermined points by using a neuronavigation system. Areas of microsurgical exposure and angles of the approaches were determined. Statistical analysis was performed to identify significant differences in the respective exposures.

RESULTS

The surgical exposure was similar for the different approaches-369.8 ± 70.1 mm2 for the ST; 341.2 ± 71.2 mm2 for the SCIT paramedian variant; and 312.0 ± 79.3 mm2 for the SCIT extreme-lateral variant (p = 0.13). However, the vertical angular exposure was 16.3° ± 3.6° for the ST, 19.4° ± 3.4° for the SCIT paramedian variant, and 25.1° ± 3.3° for the SCIT extreme-lateral variant craniotomy (p < 0.001). The horizontal angular exposure was 45.2° ± 6.3° for the ST, 35.6° ± 2.9° for the SCIT paramedian variant, and 45.5° ± 6.6° for the SCIT extreme-lateral variant opening, presenting no difference between the ST and extreme-lateral variant (p = 0.92), but both were superior to the paramedian variant (p < 0.001). Data are expressed as the mean ± SD.

CONCLUSIONS

The extreme-lateral SCIT approach had the smaller area of surgical exposure; however, these differences were not statistically significant. The extreme-lateral SCIT approach presented a wider vertical and horizontal angle to the LMS compared to the other craniotomies. Also, it provides a 90° trajectory to the sulcus that facilitates the intraoperative microsurgical technique.

Pediatric diffuse intrinsic pontine glioma: where do we stand?

Pediatric diffuse intrinsic pontine glioma (DIPG) represents approximately 20% of all pediatric CNS tumors. However, disease outcomes are dismal with a median survival of less than 1 year and a 2-year overall survival rate of less than 10%. Despite extensive efforts to improve survival outcomes, progress towards clinical improvement has been largely stagnant throughout the last 4 decades. Focal radiotherapy remains the standard of care with no promising single-agent alternatives and no evidence for improvement with the addition of a long list of systemic therapies. A better understanding of the biology of DIPG, though not easy due to obstacles in obtaining pathological material to study, is promising for the development of specific individualized treatment for this fatal disease. Recent studies have found epigenetic mutations to be successful predictors and prognostic factors for developing future management policies. The aim of this review is to give a global overview about the epidemiology, diagnosis, and treatment of DIPG. We further examine the controversial biopsy and autopsy issue that is unique to DIPG and assess the subsequent impact this issue has on the research efforts and clinical management of DIPG.

Association between extent of resection on survival in adult brainstem high-grade glioma patients

BACKGROUND

Brainstem high-grade gliomas (HGG) are rare lesions with aggressive behavior that pose significant treatment challenges. The operative use of brainstem safe entry zones has made such lesions surgically accessible, though the benefits of aggressive resection have been unclear. This study aimed to clarify the survival in adult patients.

METHODS

We utilized the SEER database (1973-2015) to analyze the association between survival and demographic data, tumor characteristics, and treatment factors in adult patients with brainstem HGGs. Patients without surgical intervention were excluded. Overall survival (OS) was analyzed using univariable and multivariable Cox regression.

RESULTS

Our dataset included a total of 502 brainstem HGG patients of which only those who had undergone surgical intervention were included in the analysis, totaling 103. Mean age was 42.4 ± 14.1 years with 57.2% (n = 59) male. Median OS of the entire cohort was 11.0 months. Median OS for patients receiving biopsy, subtotal resection, and gross total resection were 8, 11, and 16 months, respectively. Age, extent of resection, and radiation therapy were selected into the multivariable model. A significant decrease in survival was seen in older patients, 50-60 years (HR = 2.77, p = 0.002) and ≥ 60 years (HR = 5.30, p < 0.001), compared to younger patients (18-30 years). Partial resection (HR = 0.32, p = 0.006) and GTR (HR = 0.24, p < 0.001) sustained survival benefits compared to patients with biopsy only. Patients receiving postoperative radiation demonstrated no survival benefit (HR = 1.57, p = 0.161) in multivariable regression.

CONCLUSIONS

While survival of brainstem HGG patients remains poor, for surgically accessible HGGs, STR and GTR were associated with a three and fourfold increase in overall survival when compared to biopsy only.

Analysis of safe entry zones into the brainstem

Intra-axial brainstem surgeries are challenging. Many experience-based "safe entry zones (SEZs)" into brainstem lesions have been proposed in the existing literature. The evidence for each one seems limited. English-language publications were retrieved using PubMed/MEDLINE. Studies that focused only on cadaveric anatomy were also included, but the clinical case number was treated as zero. The clinical evidence level was defined as "case report" when the surgical case number was ≤ 5, "limited evidence" when there were more than 5 but less than 25 cases, and "credible evidence" when a publication presented more than 25 cases. Twenty-five out of 32 publications were included, and 21 different SEZs were found for the brainstem: six SEZs were located in the midbrain, 9 SEZs in the pons, and 6 SEZs in the medulla. Case report evidence was found for 10 SEZs, and limited evidence for 7 SEZs. Four SEZs were determined to be backed by credible evidence. The proposed SEZs came from initial cadaveric anatomy studies, followed by some published clinical experience. Only a few SEZs have elevated clinical evidence. The choice of the right approach into the brainstem remains a challenge in each case.

Diffuse Intrinsic Pontine Glioma: Time for Cautious Optimism

Diffuse intrinsic pontine glioma is a lethal brain cancer that arises in the pons of children. The median survival for children with diffuse intrinsic pontine glioma is less than 1 year from diagnosis, and no improvement in survival has been realized in more than 30 years. Currently, the standard of care for diffuse intrinsic pontine glioma is focal radiation therapy, which provides only temporary relief. Recent genomic analysis of tumors from biopsies and autopsies, have resulted in the discovery of K27M H3.3/H3.1 mutations in 80% and ACVR1 mutations in 25% of diffuse intrinsic pontine gliomas, providing renewed hope for future success in identifying effective therapies. In addition, as stereotactic tumor biopsies at diagnosis at specialized centers have been demonstrated to be safe, biopsies have now been incorporated into several prospective clinical trials. This article summarizes the epidemiology, clinical presentation, diagnosis, prognosis, molecular genetics, current treatment, and future therapeutic directions for diffuse intrinsic pontine glioma.

Microsurgical anatomy of safe entry zones to the brainstem

OBJECT

The aim of this study was to enhance the planning and use of microsurgical resection techniques for intrinsic brainstem lesions by better defining anatomical safe entry zones.

METHODS

Five cadaveric heads were dissected using 10 surgical approaches per head. Stepwise dissections focused on the actual areas of brainstem surface that were exposed through each approach and an analysis of the structures found, as well as which safe entry zones were accessible via each of the 10 surgical windows.

RESULTS

Thirteen safe entry zones have been reported and validated for approaching lesions in the brainstem, including the anterior mesencephalic zone, lateral mesencephalic sulcus, intercollicular region, peritrigeminal zone, supratrigeminal zone, lateral pontine zone, supracollicularzone, infracollicularzone, median sulcus of the fourth ventricle, anterolateral and posterior median sulci of the medulla, olivary zone, and lateral medullary zone. A discussion of the approaches, anatomy, and limitations of these entry zones is included.

CONCLUSIONS

A detailed understanding of the anatomy, area of exposure, and safe entry zones for each major approach allows for improved surgical planning and dissemination of the techniques required to successfully resect intrinsic brainstem lesions.

Pediatric brainstem abscess with hemorrhage mimicking diffuse intrinsic pontine glioma: a case report

PURPOSE

We report a rare case of brainstem abscess with hemorrhage mimicking diffuse intrinsic pontine glioma (DIPG).

METHODS

A 7-month-old baby girl presented with lethargy and poor oral feeding. She had the mild fever for 1 month. Brain computed tomography revealed the hypodense lesion in the pons. Brain magnetic resonance images (MRI) showed around 1.4-cm-sized rim-enhanced mass with perilesional edema and internal hemorrhage in the pons. The cerebral blood volume was increased in the rim-enhanced area. The provisional diagnosis was DIPG, but the mass did not show the expansile mass with encasement of the basilar artery on the ventral pons.

RESULTS

The biopsy was done via the floor of the fourth ventricle, and the pathologic findings showed the many inflammatory cells and CD68-immunopositive macrophage which were compatible with abscess. The antibiotics with ceftriaxone and metronidazole were administrated for 11 weeks, and the follow-up MRI showed the slightly small enhanced lesion without central necrotic area. Three years later, follow-up MRI revealed the encephalomalacic change and atrophy of the pons. She had the stable neurologic deficit of left facial palsy and right hemiparesis.

CONCLUSION

The biopsy could be necessary for pontine lesions without typical radiologic findings of DIPG.

Diffuse intrinsic pontine glioma: a reassessment

Diffuse intrinsic pontine glioma (DIPG) is a disease of childhood whose abysmal prognosis has remained unchanged for over 50 years. Biologic investigation has been stymied by lack of pretreatment tissue, as biopsy has been reserved for atypical cases. Recent advances in surgical and molecular-analytic techniques have increased the safety and potential utility of biopsy; brainstem biopsy has now been incorporated into several prospective clinical trials. These and other recent efforts have yielded new insights into DIPG molecular pathogenesis, and opened new avenues for investigation.

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.

Gross total surgical removal of malignant glioma from the medulla oblongata: report of two adult cases with reference to surgical anatomy

Surgery was performed on the medulla oblongata of two adult patients with malignant glioma. Gross total resection of the tumors, located laterally or medially in the upper half of the medulla respectively, was achieved. The patient with the medially located tumor experienced significant postoperative neurological deterioration including sleep apnea. The other patient with the laterally located tumor showed symptomatic improvement without respiratory complications. The patient with an anaplastic astrocytoma survived approximately 4 years and the patient with a glioblastoma multiforme approximately 2 years. Although the upper half of the medulla is more critical than the lower half, a lateral approach to the upper half of the medulla appears to be relatively safer than a medial approach. Some cases of focal malignant gliomas in the medulla may be amenable to gross total resection in order to achieve improved outcome. Surgery can be undertaken when a tumor is unilateral and its margin appears relatively clear on magnetic resonance images.

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.

The anatomical aspects of a surgical approach through the floor of the fourth ventricle

In 1993 Kyoshima et al. introduced safe entry zones in the region of the 4th ventricle floor: infrafacial triangle and suprafacial triangle. Is it possible to demarcate these zones precisely in every case intra-operatively? A postmortem study of 40 brainstems of patients who had died of non-brain disease was performed to evaluate the degree of individual morphological and morphometrical variability of the 4th ventricle floor. The purpose of this study was to find constant landmarks and distances within the rhomboid fossa region which would help a neurosurgeon to determine safe approach zones through the 4th ventricle floor to brainstem lesions. Several anatomical landmarks-median sulcus, obex, vestibular area, vagal triangle, hypoglossal triangle-were found to be sufficiently visible in all examined brainstems. However, the facial colliculus which is a border structure between the infrafacial and suprafacial safe approach zone was poorly visible in about 37% of the analyzed material. The striae medullares were not found to be good orientation structures as they were not visible in 30% of the material and exhibited individual variability of a high degree in relation to their number and arrangement. In the morphometrical study analyzed measurements were taken by utilizing the digital image analyzer MULTISCAN. Based on the results obtained the authors suggest new borders of the infrafacial safe approach zone and morphometrical directions to determine the suprafacial safe approach zone in cases when the facial colliculus is not clearly visible or invisible intra-operatively.

Computerized tomography-guided stereotactic surgery for brainstem masses: a risk-benefit analysis in 71 patients

The benefits of the use of computerized tomography (CT)-guided stereotactic surgical techniques for the management of intrinsic brainstem masses diagnosed from clinical evaluation and imaging studies were evaluated vis-à-vis the risks involved in 71 consecutive patients. Seventy-two procedures were performed. The masses were diffuse, involving two or three contiguous brainstem segments, in 60 patients and focal in 11 patients. On the CT scans, 25 patients had hypodense nonenhancing masses, two had isodense nonenhancing masses, 19 had ring-enhancing masses, and 25 had heterogeneously enhancing masses. A positive biopsy was obtained in 68 of 69 patients (98.5%) undergoing a biopsy procedure. In nine patients (12.6%) with suspected malignant masses a benign pathology was diagnosed (four tuberculomas, two epidermoid cysts, one pyogenic abscess, one epidermal cyst, and one case of encephalitis). Additionally, fluid from cystic masses could be aspirated in eight cases, providing benefit in six (four patients had benign lesions and two had neoplastic lesions). Thereby, a total of 13 patients (18.3%) were deemed to have benefited from the surgery (two patients were included in both categories). Patients with focal masses and ring-enhancing masses had the highest proportion of benign lesions (60% and 36.8%, respectively) and therefore derived the most benefit from histological verification. There was no procedure-related mortality. One patient (1.4%) suffered permanent morbidity and four others (5.6%) had transient worsening attributable to the procedure. The authors conclude that CT-guided stereotactic surgery of the brainstem is safe and reliable. Histological verification of all enhancing (especially ring-enhancing) and focal brainstem masses should be undertaken to identify patients with benign nonneoplastic lesions. Selected patients with diffuse hypodense nonenhancing masses with atypical clinical or imaging features may also benefit from stereotactic biopsy. Even in these patients the lack of enhancement on a contrast-enhanced magnetic resonance image, rather than the diffuse location of the tumor alone, should form the basis for diagnosing a malignant glioma. The main value of stereotactic surgery lies in the identification of benign masses in a significant proportion of patients with intrinsic brainstem masses and in providing a rapid and safe method for evacuation of the contents of cystic masses.

Stereotactic biopsy of brainstem mass lesions

BACKGROUND

Appropriate therapy of brainstem lesions is guided by accurate diagnosis. Because the majority of brainstem lesions are not amenable to surgical resection, stereotactic biopsy is an attractive method of obtaining pathological tissue.

METHODS

We reviewed the medical records of all patients who underwent stereotactic biopsy of brainstem mass lesions at our institution by the senior author (WAF) over a 10-year period ending in December 1993.

RESULTS

Twenty-four patients ranging in age from 3 to 68 years underwent stereotactic biopsy of brainstem mass lesions at our institution by the senior author (WAF) over a 10-year period ending in December 1993.

RESULTS

Twenty-four patients ranging in age from 3 to 68 years underwent stereotactic biopsy of mass lesions of the brainstem. Sixteen lesions were located primarily in the pons, 7 in the midbrain, and 1 in the medulla. Twenty-two of the biopsies were approached transfrontally and two were approached via the suboccipital transcerebellar route. Pathological diagnosis was made in 23 of the 24 patients. The histologic diagnosis was astrocytoma in 16 patients, metastasis in 3, lymphoma in 1, germinoma in 1, chordoma in 1, progressive multifocal leukencephalopathy in 1, and was nondiagnostic in 1. Complications included 1 case of increased hemiparesis, 1 case of obstructive hydrocephalus, and 1 death. Six patients were less than 20 years of age and in each of these patients the preoperative diagnosis was astrocytoma. In all of these patients the pathology revealed astrocytoma. In the adult patients the pathology was more varied, with 7 of the 18 patients having tumors or pathology other than astrocytoma.

CONCLUSIONS

The data suggest that, in adult patients, brainstem lesions are of varied pathology and stereotactic biopsy can provide adequate tissue for diagnosis. The data also suggest that the diagnosis of brainstem glioma in children can often be made without submitting the patient to the risk of surgery.

[Benign intrinsic tectal tumors: apropos of 2 cases]

The introduction of computerized tomography and magnetic resonance imaging led to the knowledge that brain stem tumors are not a homogeneous group with regard to their clinical, pathological and biological features. The classical concept of an uniformly poor prognosis has been modified and some subtypes of tumors are amenable to surgical treatment and long-term survival. The authors report two cases of patients with tumors of the tectal region whose symptoms and CT features were consistent with late-onset aqueductal obstruction. In both cases definitive diagnosis was established by MRI and symptoms resolved after ventriculo-peritoneal shunt implantation. The clinic and pathological features and therapeutical alternatives as well, are discussed.

Focal brain-stem astrocytomas causing symptoms of involvement of the facial nerve nucleus: long-term survival in six pediatric cases

Six children with a history of isolated facial nerve dysfunction or dizziness and nausea were treated for brain-stem glioma between 1984 and 1992. Computerized tomography and/or magnetic resonance (MR) imaging showed a focal, uniformly enhancing mass involving the facial nerve nucleus of the pons. All patients underwent biopsy; the histological diagnosis was juvenile pilocytic astrocytoma in five cases. In the remaining case the biopsy was nondiagnostic, although the surgeon believed that the lesion was a glioma. Postoperatively, five patients underwent conventional focal megavoltage radiation therapy (180 to 200 cGy/day) over a period of 5 1/2 weeks to a total dose of approximately 5400 cGy. One child's family refused radiation therapy; she remained well and stable for 4 years, despite persistent facial weakness, and was eventually lost to follow-up review. Four irradiation-treated patients had complete resolution of their tumors on MR images and have had no evidence of neuropsychological or neuroendocrinological deficits during 4 1/2 to 8 years of follow-up evaluation. Patients whose neuroradiological studies show a lesion resembling those in this series should undergo biopsy and, if the histology of a low-grade tumor (in particular, a juvenile pilocytic astrocytoma) is confirmed, should then receive focal radiation therapy with conventional megavoltage dosages.

Surgical management of brain-stem tumors in children: results and statistical analysis of 75 cases

A study was made of 75 children treated between 1970 and 1990, with partial, subtotal, or total removal of three intrinsic and 72 exophytic or surface brain-stem tumors. In all cases, the goal of surgery was to remove as much tumor as possible. Extent of removal was defined according to data obtained from postoperative computerized tomography or magnetic resonance imaging, and was considered partial when only a small amount of tumor was removed, subtotal when a few cubic millimeters of tumor was left, and total when no residual tumor was seen on postoperative radiological investigations. An ultrasonic aspirator was used for the 43 most recent operations. Among tumor removals without the aspirator, 24 (75%) were partial, eight (25%) subtotal, and none total; with the use of the aspirator, the number of partial removals decreased to 44.5% while that of subtotal and total removals increased to 32% and 23.5%, respectively. There were 69 gliomas (92%) and 47 benign tumors (62.6%). Forty-nine patients were irradiated postoperatively, and 14 of the 23 patients whose benign tumors were removed totally or subtotally did not undergo irradiation. This study showed that: 1) the overall prognosis of patients with malignant tumors was poor and was not improved by surgery; 2) the survival rate of those with benign tumors was significantly (p < 0.01) lower after partial removal than after total or subtotal removal (52% and 94%, respectively, at 5 years); 3) comparison of means and proportions (Student's and chi-squared tests) between benign and malignant tumors showed a significant difference relating to patient age (p < 0.03), peritumoral hypodensity (p < 0.001), and preoperative duration of symptoms (p < 0.001); 4) stepwise logistic regression analysis confirmed that two of these three variables were related to malignancy: namely, patient age at surgery (p < 0.03) and presence of peritumoral hypodensity (p < 0.001); and 5) routine postoperative irradiation was contraindicated after total or subtotal removal of benign tumors.

Management and outcome of low-grade astrocytomas of the midline in children: a retrospective review

Low-grade astrocytomas of the midline of the brain can be difficult to manage because of their location. To evaluate treatment and outcome, we performed a retrospective study of children with midline low-grade astrocytomas admitted to The Hospital for Sick Children between 1976 and 1991. Eighty-eight children with biopsy-proven low-grade astrocytomas were identified. Forty-three tumors occurred in the optic pathways or hypothalamus, 13 in the thalamus, 7 in the pineal region, 14 in the midbrain, and 11 in the medulla. Patient follow-up ranged from 6 months to 15 years, with a mean of 4 years, 9 months. Overall outcome was related to the extent of resection, histological type, and location. Partial resections were often associated with involution of the tumor. Response to radiation was variable, and serious sequelae were observed. Thirty-three patients experienced recurrence, often with a good response to subsequent surgery; however, 12 of these patients died. The probability of survival was calculated to be 96% at 1 year, 91% at 5, and 80% at 10 years. Our study suggests that resection should be considered in all patients, both at presentation and recurrence.

The long-term outcome after surgical treatment of dorsally exophytic brain-stem gliomas

Dorsally exophytic brain-stem gliomas represent a distinctive subgroup of pediatric brain-stem neoplasms that are amenable to radical excision because of their benign histology and growth characteristics. However, their attachment to the floor of the fourth ventricle invariably precludes complete tumor excision. The long-term behavior of the residual tumor remains a subject of concern. To address this issue, the authors reviewed their experience with 18 dorsally exophytic brain-stem gliomas treated between 1974 and 1990. At operation, the tumors filled the fourth ventricle, fungating out of a broad-based area of the dorsal brain stem. The exophytic tumor was resected, but no attempt was made to remove tumor from the brain stem. Histological examination showed that 16 of the tumors were grade I or II astrocytomas, one was a ganglioglioma, and one was an otherwise benign-appearing glioma with several foci of anaplasia that was classified as a grade III astrocytoma. The latter patient was one of only two in the series to receive postoperative radiation therapy; both cases so treated have no evidence of disease on follow-up imaging studies 61 and 135 months postoperatively. One other child who had stable disease postoperatively died of shunt malfunction 18 months after tumor excision. Serial radiographic studies in the other 15 patients have shown no evidence of disease in three, stable residual disease in eight, and tumor enlargement 12, 28, 40, and 84 months postoperatively in four (median follow-up period 113 months). Each of the four patients with tumor regrowth underwent repeat tumor excision. Two of these children received perioperative radiation therapy at the time of disease progression and both showed reduction in tumor volume 28 and 65 months after their second operation. In contrast, both patients who did not receive radiotherapy at the time of disease progression had further tumor enlargement 48 and 84 months after their second operation and underwent a third tumor resection; one received postoperative radiation therapy and has no evidence of disease 58 months after his third operation and the other child has stable disease 27 months postoperatively. Histological examination of tumor specimens obtained at second and third operations showed no change from the appearance of the tumor on the initial resection. The authors conclude that the majority of dorsally exophytic brain-stem gliomas can be managed successfully with subtotal excision and, if necessary, cerebrospinal fluid diversion. The small percentage of tumors in this series that showed recurrent growth remained benign histologically.(ABSTRACT TRUNCATED AT 400 WORDS)

Surgical removal of brainstem astrocytomas and hemangioblastomas: report of three cases and review

The surgical removal of a brainstem astrocytoma or hemangioblastoma entails the risk of a major neurological injury, but if injury can be avoided, the benefits of surgery are considerable in some types of these tumors. Most brainstem astrocytomas are widely infiltrative diffuse tumors that frequency undergo malignant change and are not benefitted by surgery. However, dorsally exophytic brainstem astrocytomas, focal cervicomedullary astrocytomas, and focal brainstem astrocytomas have a more benign character and frequently are benefitted by surgical removal or other surgical intervention. Brainstem hemangioblastomas may be extramedullary tumors or cystic intramedullary tumors, and surgical removal of these tumors is usually possible and is the optimal treatment. Three cases are presented to illustrate that excellent results can be obtained by surgical resection of certain types of brainstem astrocytoma or hemangioblastoma. The clinical and radiographic characteristics and the results of surgical treatment for each of these types of brainstem tumor are discussed.

Physiological localization of the facial colliculus during direct surgery on an intrinsic brain stem lesion

We designed a method for localizing facial colliculus intraoperatively by means of weak stimulation of the 4th ventricular floor and recording the electromyographic response of the facial muscle. This method is applicable clinically to prevent 6th and 7th cranial nerve complications during direct surgery on an intrinsic lesion of the brain stem, in which the normal anatomy of the rhomboid fossa is often distorted.

Image directed stereotactic surgery for brain stem lesions

Advances in neurological imaging may have increased the diagnostic accuracy and the detection rate of intrinsic brain stem lesions, but a histological diagnosis is still an essential requirement for rational and appropriate management. Open exploration allows biopsy and resection in cases where an exophytic component is present. The surgical inaccessibility and the resultant morbidity of these approaches, however, associated with a low diagnostic yield in cases with no visible surface abnormality, are important limiting factors. A series of 45 brain stem lesions stereotactically approached with CT or MRI guidance is presented. A transcortical frontal pre-coronal trajectory was used in all of them. Haematoma was preoperatively diagnosed in 10 cases and the procedure was for therapeutic aspiration. Of 35 cases where the diagnosis was uncertain, although intrinsic tumour was suspected, positive results were obtained in 33, while unexpected findings of granuloma, lymphoma, angioma, leucoencephalopathy, vasculitis and radiation necrosis were found in over 10% of the cases. There were no operative deaths and the morbidity was low. In no case was there a permanent neurological deterioration directly related to the procedure, although there was a transient deterioration in two patients and one patient required early reaspiration of a haematoma. Image directed stereotactic approaches to brain stem lesions can combine a high degree of accuracy (offering positive histological diagnoses) with a low operative morbidity. MRI directed biopsies can complement CT guided ones thus increasing the number of suitable cases and improving the success rate. The frontal precoronal transcortical trajectory provides safe access to the majority of the brain stem targets.

Brain stem glioma: the role of a biopsy

A retrospective review of the clinical and histopathological features of 31 patients with brain stem gliomas treated between 1965 and 1990 at Kyushu University Hospital was performed to determine the role of biopsy on these lesions. These 16 male and 15 female patients ranged in age from 3 to 50 years at diagnosis (average: 18.1 years). The primary site of the tumour was the pons in 20 patients, followed by the medulla oblongata and midbrain, and the final histological diagnoses of the lesions based on either the biopsy or autopsy materials were grade I astrocytomas in five patients, grade II in nine, grade III in 10, grade IV in five, and ependymoma in two patients. No consistent correlation could be obtained between the CT findings and histological diagnoses. Open surgical posterior fossa exploration was performed on 17 patients (diagnostic biopsy: 10; volume reduction by tumour removal with or without cyst evacuation: 7) and stereotaxic biopsy on three patients, without any mortality related to these procedures. In our biopsy series, half of the patients with grade II astrocytoma died within 12 months after diagnosis, whereas three out of four patients with grade I astrocytoma survived more than 10 years after diagnosis. Because of the relative safety of the tissue sampling technique, and the importance of an accurate diagnosis in order to select appropriate treatment modalities, histological verification of the lesion should be considered for all patients harbouring a brain stem mass lesion.

Reversible neurotoxicity following hyperfractionated radiation therapy of brain stem glioma

Two patients with brain stem gliomas were treated with hyperfractionated radiation therapy (HFR) (7,020 and 7,560 cGy, respectively). Despite initial clinical improvement during irradiation, both patients demonstrated clinical deterioration approximately 3 weeks after completion of radiotherapy. Cranial magnetic resonance imaging (MRI) revealed a progressive increase in distribution of abnormal brain stem signal consistent with either tumor or edema. 18FDG positron emission tomography (PET) was obtained in one patient and demonstrated a hypermetabolic lesion at diagnosis and a hypometabolic lesion at the time of clinical deterioration postirradiation. Management with a tapering dose of dexamethasone alone resulted in marked clinical (both patients) and radiographic (one patient) improvement, allowing reduction or discontinuation of this medication. These results suggest that patients with brain stem tumors demonstrating clinical and radiographic evidence of progressive tumor shortly after completion of HFR should be initially managed conservatively with dexamethasone, since these findings may be manifestations of reversible radiation-related neurotoxicity.

Direct surgery for brainstem tumours

Updating a previous report, the authors offer a review of 45 patients between age 2 and 63 treated by direct surgical excision for brainstem tumours of various description. Since 1986 all candidate patients were examined by NMR imaging in addition to CT scanning, sometimes with the further addition of digital-subtraction vertebral angiography. By Epstein and McLeary's criteria, 24 of the tumours were focal, 12 were cervicomedullary and 9 were diffuse. The most frequent histological diagnosis was glioma (36 cases between low-grade astrocytoma, anaplastic astrocytoma and glioblastoma); the balance was provided by cavernoma (6 cases), haemangioblastoma (2 cases), and lipoma (2 cases). Gross total resection was achieved in 28 patients, namely all those with ependymoma or vascular tumours and 14 of 17 with low-grade astrocytoma. Resection was subtotal in 16 cases and confined to a generous biopsy in one. There was no operative mortality, but 2 deaths occurred in the early postoperative period. At discharge, neurological status was unchanged or improved in 35 cases. At 3-month follow-up examination, 12 patients were improved, 27 were unchanged and 3 were worsened. By January 1990 (6 to 72 months postoperatively) 27 of the first 40 patients treated were alive: 13 had resumed normal life, 6 were self-sufficient and 8 were disabled. The authors conclude that present-day microsurgical resection of intra-axial brainstem tumours is associated with low mortality and morbidity and affords favourable results for which they credit high-quality NMR imaging, efficient microsurgery, adequate anesthesia, and competent postoperative intensive care.

Stereotaxic biopsy of brain-stem tumours in children

Stereotaxic biopsies were performed in a series of 14 patients with clinical and computed tomographic evidence of a brain-stem lesion. Seven of these cases were in the paediatric age group (under 15 years of age). Biopsies were obtained by means of the Leksell stereotaxic system, through the transcerebellar (three cases) or transfrontal route (four cases). A definite tumour diagnosis could be obtained in all cases. No patients were subjected to open biopsy, as the further management of their tumours did not warrant surgery. One patient developed transient oculomotor nerve palsy. There was no mortality related to the biopsy procedure in this series. The biopsy technique and its utility and safety are discussed.

Surgical management of hematomas of the brain stem

Nine patients with brain-stem hematoma were admitted to the authors' institute during the period from 1985 to 1988. Clinical symptoms and signs pointed to pontine involvement in most cases. Progressive clinical deterioration was quite common and usually led to a clinical diagnosis of brain-stem intra-axial tumor. Angiography was noncontributory; computerized tomography (CT) was the main diagnostic test. This gave evidence of different pathological characteristics, including masses showing highly increased density, nonhomogeneous hyperdense lesions, and isodense lesions with peripheral contrast enhancement. No clear correlation was found, however, between the presumed duration of the clinical picture and the CT characteristics of the lesion. In the last four cases, magnetic resonance imaging was performed using a 0.015-tesla resistive system. This examination usually confirmed the presence of a brain-stem mass already shown by previous CT scans. There were, however, no cases in which direct evidence of an intra-axial vascular malformation could be obtained. The patients were all treated surgically with an attempt at total removal of the lesion and thorough inspection of the hematoma cavity and biopsy. Evidence of "cryptic" arteriovenous malformation was obtained in six of the nine cases. There were minor transitory complications in three cases. All of the patients were able to resume their previous activity, and none suffered recurrence of the symptoms following the operation. It may be concluded that surgery is the treatment of choice for brain-stem hematoma.

Prognostic factors and results of therapy for adult thalamic and brainstem tumors

This report is a retrospective analysis of 83 adults (greater than 16 years of age) with histologically proven or presumed primary neoplasms of the thalamus, hypothalamus, midbrain, pons, and medulla. Patients were treated with combined surgery and postoperative irradiation or with irradiation alone at the Washington University Medical Center (St. Louis, MO) from January 1950 through December 1984. Histologic analysis confirmed the diagnosis of tumor in 21, including nine with well-differentiated astrocytoma, four with astrocytoma with anaplasia, and eight with glioblastoma multiforme. Overall and disease-free survivals at 5 years were 28.7 and 23.2%, respectively. A statistical analysis was performed to ascertain the prognostic importance of the following variables: age, race, gender, duration of symptoms, cranial nerve paresis, primary site, extent of surgery, histology, and irradiation dose. The only factor identified by univariate analysis to be critical for survival was primary location of disease. Patients with supratentorial (thalamus/hypothalamus, midbrain) tumors had a 10-year disease-free survival of 15.4% compared to 29.6% for those with infratentorial (pons, medulla) tumors (P = 0.07). Patients with lesions of the pons had a 5-year disease-free survival of 35.8% compared to 13.8% for those with tumors of the thalamus (P = 0.05). Increasing irradiation dose was not correlated with superior survival. Factors evaluated but established to be insignificant were age (P = 0.27), race (P = 0.63), gender (P = 0.27), duration of symptoms (P = 0.19), cranial nerve paresis (P = 0.71), histologic type (P = 0.16), and extent of surgery (P = 0.94). Follow-up for 13 surviving patients ranged from 2.6 to 28.7 (mean, 12.0) years. Neurologic deficits in surviving patients were absent in 15% (two of 13), mild in 62% (eight of 23), and moderate in 23% (three of 13). One case of brain radionecrosis was identified (6000 cGy, 200 cGy daily).

Hyperfractionated radiation therapy for brain-stem glioma: a phase I-II trial

Fifty-three patients (19 adults and 34 children) harboring brain-stem glioma were treated with hyperfractionated radiation therapy (100 cGy twice a day, 5 days/wk, to a total dose of 7200 cGy). For the entire group, the median time to tumor progression (TTP) was 59 weeks (adults 66 weeks, children 44 weeks) and the median survival time was 74 weeks (adults 92 weeks, children 64 weeks). Statistically significant prognostic factors associated with a decrease in TTP and median survival times (adults less than children) were: patient's age, a clinical history of less than 2 months, widespread brain-stem dysfunction, and a diffuse tumor as seen on magnetic resonance imaging. A finding of glioblastoma multiforme at histological analysis was associated with a statistical trend toward poorer survival, but in general tumor histology was not predictive of outcome. No evidence of an increase in acute or delayed radiation toxicity was seen with this fractionation schedule and total dose. This study suggests that hyperfractionation prolongs the TTP and survival time for many patients with brain-stem glioma. However, there remains a group of patients who are only moderately helped by this technique and for whom more aggressive treatment is warranted.

Multivariate analysis of prognostic factors in pediatric and adult thalamic and brainstem tumors

A multivariate analysis of prognostic variables was performed on a retrospective review of 136 patients with presumed or histologically proven primary lesions of the thalamus and brainstem treated by combined surgery and post-operative irradiation or by irradiation alone from January 1950 through December 1983. Overall survival for all patients at 5 and 10 years was 34.4 and 27.8%, respectively. Follow-up of 33 living patients ranged from 3 to 22 years. Prognostic variables analyzed by univariate analysis and found to be of significance (p less than 0.05) were race, duration of symptoms, extent of surgery (i.e. subtotal excision), and dose of irradiation. Further evaluation by Cox regression analysis revealed these same factors to be of prognostic significance (p less than 0.05). It is of importance to note that age and tumor site were not significant prognostic variables in the multivariate analysis but were significant by univariate analysis. The 5-year overall survival for patients with thalamic tumors was 59.5 and 20.9% for children and adults, respectively (p = 0.006). The 5-year overall survival for patients with pontine lesions was 46.6 and 16.0% for adults and children, respectively (p = 0.01). Only one patient was known to have expired due to a complication of therapy. Neurologic deficits and functional ability was normal or mild in 57.6% of the surviving patients.

Undifferentiated gliomas of the brain stem

Undifferentiated gliomas of the brain stem were confirmed surgically in two young children. The patients were treated by aggressive irradiation of the entire neuraxis, similar to that administered for medulloblastoma. Therapy resulted in a good prognosis and there was no tumor recurrence.

Stereotaxic suboccipital transcerebellar biopsy of pontine mass lesions

Twenty-six patients (16 male and 10 female) ranging in age from 5 to 68 years underwent suboccipital transcerebellar stereotaxic biopsy of mass lesions situated in the pons. Stereotaxic computerized tomography, magnetic resonance imaging, and angiographic data were obtained while the patient was positioned in an inverted custom stereotaxic head frame. The patients were then placed under general endotracheal anesthesia and positioned prone. Optimal trajectory planning utilized a transcerebellar route directed through the middle cerebellar peduncle, with target and entry points calculated to avoid vascular structures. No complications were encountered in the perioperative period when this technique was used. Histological diagnosis of the lesions revealed: astrocytomas in 14 patients, oligodendroglioma in one, ependymoma in one, arteriovenous malformations in two, radionecrosis in one, cryptococcal abscess in one, demyelinating disease in three, and infarctions in three. No consistent correlation could be made between radiographic characteristics and histological diagnoses. Empiric treatment of brain-stem lesions without tissue diagnosis based upon the radiological and clinical findings may result in inappropriate therapy administration. Alternatively, open operative procedures to obtain tissue require a visible surface abnormality to guide biopsy, and carry the risks of a major surgical procedure in already compromised patients. For these reasons the authors consider a suboccipital transcerebellar stereotaxic biopsy to be the diagnostic procedure of choice in the assessment of pontine mass lesions.

Experience in 300 cases of CT-directed stereotactic surgery for lesion biopsy and aspiration of haematoma

Despite advances in imaging of the brain, an accurate diagnosis of brain lesions requires tissue sampling and histological verification. A series of CT-directed procedures has been performed in 300 patients with deep sited, multiple, diffuse, extensive, small or inflammatory lesions, brain stem haematomas and tumours presenting with epilepsy. A positive diagnosis was obtained in 271 cases (92.8%), no diagnosis in 21 cases (7.2%). Therapeutic results were also obtained in eight cases (2.7%) of brain stem haematoma aspiration. Complications occurred in 14 cases (4.7%) including one death (0.3%). Because of the importance of an accurate diagnosis in order to avoid inappropriate therapy, together with the relative safety of the technique, CT-directed stereotactic biopsy should be considered in all patients harbouring deep seated, multiple, diffuse, small or inflammatory brain lesions.

Brain stem gliomas: a clinicopathological analysis of 23 histologically proven cases

The clinical and anatomic pathological findings in 23 patients with histologically proven brain stem glioma were reviewed. Eleven patients had malignant tumors (astrocytoma, grade III, and glioblastoma multiforme) and the remaining had low grade ones. The primary site of the tumor was the pons in 15 of 21 patients examined, followed by the medulla oblongata and midbrain. Continuous cephalad and caudad involvement of pontine tumors was evident in 14 patients, and was more extensive in the high grade gliomas. At autopsy, the tumor spread via the CSF was observed in all patients with high grade but not low grade tumors. Open surgical posterior fossa exploration was performed on 12 patients. Volume reduction, by partial removal of the tumor and/or by cyst evacuation, was performed on seven, with good results. Nineteen patients were given radiation therapy, with temporary improvement of the clinical conditions. While none of the patients with malignant tumors survived more than 15 months after diagnosis, those with low grade tumors had a five-year actuarial survival rate of 50.0%, and three survived more than ten years after the diagnosis. Our data indicate that brain stem gliomas are not a homogeneous group of tumors as far as the clinical and pathological features are concerned. This heterogeneity shows the need to design specific treatments for these tumors.

Brainstem haematomas: review of the literature and presentation of five new cases

Fifty-one cases of brainstem haematoma that have undergone neurosurgical intervention since Finkelnburg's first exploration in 1905, are presented, together with five new cases. The location, incidence, aetiological and pathological factors, as well as clinical syndromes are reviewed. Diagnostic criteria are presented. The distinction between brainstem "haematoma" and "haemorrhage" is stressed. A retrospective comparison of 56 surgically treated cases and 31 conservatively managed cases is made, as is an analysis of the natural history of the disease process. Based on currently available data, the conclusion is drawn that patients with brainstem haematomas fare quite well after surgical therapy.

Stereotactic biopsy and treatment of brain stem lesions: combined study of 33 cases (Bologna-Marseille)

Intraaxial brain stem tumours are rarely treated by open surgical technique. In Bologna and Marseille, 23 and 10 stereotactic biopsies respectively were performed in patients with brain stem mass lesions. The mortality due to biopsy was 3% (1 pat.); while the morbidity was temporary in 6 cases (18%) and permanent in one patient (3%). The approach to the brain stem was via a frontal burr hole. 7 times, after biopsy and histological diagnosis, radioisotope implant of the neoplasm was performed with 125I (iodine). From the histological diagnoses of the lesions the following was found: only 40% of the young patients had highly malignant tumours; 83% of the adults had neoplasms (not all of the malignant type), while 17% of the verified lesions were non-neoplastic. Since a diagnosis of the lesion nature is impossible with current neuroradiological means, the authors noting a variety of masses found in their experience, emphasize the importance of stereotactic biopsy, as a scarcely invasive method to give a precise diagnosis and a possible treatment.

Microsurgery of midbrain lesions

Between 1973 and 1987 a total of 38 patients with midbrain lesions were encountered. In 15 cases surgical exploration was not warranted, 23 patients underwent definitive surgical exploration. The infratentorial supracerebellar approach proved to be the ideal route for the exposure of the 21 lesions which were located in the more dorsal aspect of the midbrain; in 7 cases the extension of the mass lesion reached from the cerebellum into the midbrain and, therefore, the exposure demanded a transcerebellar route. In one case with a hamartoma in the interpeduncular cistern and another case of a metastasis of the right cerebral peduncle the subtemporal approach was chosen. Three patients died as a consequence of the operation, but in the other 20 there was no increase in morbidity after surgery and the immediate postoperative course was favourable. Four cases with malignant tumours died from recurrence despite radiotherapy. The remaining 16 cases have been doing well up to 14 years after surgery.

The relevance of pathological diagnosis for therapy and outcome of brain stem gliomas

41 patients with brain stem gliomas are presented and analyzed. Optimal therapy as well as outcome depend on the histological identity of the tumours. Histological examination cannot be replaced by CT, angiography and NMR. Therefore stereotactic biopsies are recommended in all cases with brain stem gliomas.

Irradiation of primary thalamic and brainstem tumors in a pediatric population. A 33-year experience

A retrospective analysis of 70 pediatric patients (less than 16 years of age) with histologically proven or presumed primary neoplasms of the thalamus, hypothalamus, and brainstem, treated with combined surgery and postoperative radiotherapy or radiotherapy alone at the Washington University Medical Center from January 1950 through December 1983, is reported. Overall survival for all patients at 5 and 10 years was 34.9% and 32.7%, respectively. Follow-up of the 22 surviving patients ranged from 3.0 to 20.0 years (median, 10.6 years). Statistical analysis of multiple prognostic factors was performed. Prognostic factors found by single variate analysis to significantly influence survival were primary site of disease, extent of surgery, race, cranial nerve paresis at diagnosis, and dose of radiation. Factors evaluated but found to be insignificant were age at diagnosis, duration of symptoms before diagnosis, sex, and volume irradiated. Multivariate analysis revealed that only total radiation dose and race were of prognostic significance.

Brain-stem tumors in childhood: a prospective randomized trial of irradiation with and without adjuvant CCNU, VCR, and prednisone. A report of the Childrens Cancer Study Group

Seventy-four children with a brain-stem tumor diagnosed between 1977 and 1980 were entered into a prospective study in which exploration and assessment for resection were optional, radiation treatment using standard methods was required, and randomization occurred with regard to the use of adjuvant chemotherapy (1-(2-chloroethyl)-1-nitrosourea, vincristine, and prednisone) or no further treatment. The overall 5-year survival rate was 20% and was not improved by the adjuvant chemotherapy program. An increased risk of infection was associated with the adjuvant therapy.

Diagnosis and management of pediatric brain-stem gliomas

The authors reviewed the cases of 49 children, ranging in age from 9 months to 15 years, who were diagnosed by computerized tomography (CT) as having brain-stem glioma. Four distinct groups of brain-stem gliomas were identified based on CT scan characteristics: Group I included isodense contrast-enhancing tumors that were dorsally exophytic into the fourth ventricle; Group II(a) included hypodense nonenhancing intrinsic tumors of the brain stem; Group II(b) included intrinsic tumors of the brain stem with hyperdense exophytic components extending ventrally and laterally into the cerebellopontine and prepontine cisterns; Group III included intrinsic cystic tumors with contrast-enhancing capsules; and Group IV included focally intrinsic tumors of the brain stem that were isodense and enhanced brightly on administration of contrast medium. The clinical presentation, efficacy of surgical intervention, pathology, and prognosis of these tumors were correlated within these groupings. Eleven patients had Group I tumors, all of which were surgically resected; 10 of the 11 lesions were proven to be low-grade gliomas. These patients had an excellent prognosis; 10 of the 11 survived, with a mean follow-up period of 4.5 years. There were 18 patients with Group II(a) tumors; although tumor biopsy was attempted on eight of these, pathological diagnosis at the time of surgery was made in only one case. These patients did poorly; the mean survival time was 6.2 months. The seven Group II(b) tumor patients demonstrated a similarly poor prognosis: all of them died within 23 months of diagnosis, with a mean survival time of 12 months. Only two of six patients undergoing biopsy had sufficient tissue for histological verification. Three of the four patients with Group III tumors died; their mean survival time was 11.5 months. Successful histological examination was carried out in all four cases. The nine Group IV tumor patients did reasonably well; seven of these patients remain alive, with a mean follow-up period of 2.3 years. Histological diagnosis was obtained in three of the seven patients who were explored in this group. This classification system has proven to be of value in determining prognosis and efficacy of surgical intervention.

Brain stem tumors in children: results of a survey of 62 patients treated with radiotherapy

A survey was conducted by the Radiation Oncology Discipline Committee of the Pediatric Oncology Group to provide an estimate of the outcome of treatment with modern radiotherapy of brain stem tumors in children. Thirteen of thirty-eight institutions submitted data for 62 patients who had been diagnosed between 1972 and 1981, who had completed planned treatment with radiotherapy, and for whom follow-up information was available. The results were poor. Fourteen patients were alive with no evidence of recurrence between 11 and 154 (median 50.5) months post-treatment, two were alive with disease at 22 and 24 months, and forty-six died of disease at intervals ranging from 2 to 30 (median 8.7) months from initiation of treatment. Actuarial survival was 50% at 1 year, 29% at 2 years, and 23% at 5 years. The age of the patient, the surgical approach, and the volume and dose of radiotherapy all appeared to correlate with outcome on univariate analysis; but on multivariate analysis a statistically significant survival advantage was found only for patients greater than 5 years of age who had undergone surgery as part of their treatment. Possible explanations for these findings are discussed, and the roles of surgery, radiotherapy, and chemotherapy are reviewed.