J Neurosurg (2 Suppl Pediatrics) 104:108–114, 2006 108 J. Neurosurg: Pediatrics / Volume 104 / February, 2006 LTHOUGH the prognosis for patients with diffuse pontine gliomas remains dismal, focal, exophytic, and cervicomedullary gliomas have proven to be amenable to resection. The treatment of these resectable brainstem tumors has progressively improved as more so- phisticated imaging and microsurgical techniques have allowed safe excision of a greater percentage of these le- sions. Once considered inaccessible, the brainstem can now be approached for biopsy sampling and resection. In many cases, pontine glioma can be diagnosed on the basis of characteristic patterns on MR images. Even though brainstem gliomas exhibit typical imaging characteristics, occasionally instances arise in which MR imaging and a patient’s clinical history cannot effect a definitive diagno- sis. In addition, some benign pathological conditions, such as demyelination, radiation necrosis, encephalitis, and the presence of a cystic lesion, can mimic diffuse glioma on MR images. 1,19 In cases involving unresectable lesions not exhibiting the classic MR imaging and clinical features of diffuse glioma, stereotactic biopsy sampling provides a safe and accurate diagnostic modality. Clinical Material and Methods Patient Population A total of 10 pediatric patients (six boys and four girls) presented to our institution with brainstem lesions for which MR imaging could not provide a conclusive diagnosis. Moreover, these lesions were judged inappropriate for open resection. Finally, because all of the patients were symp- tomatic or had documented lesion progression, follow-up neuroimaging alone was presented as a treatment alterna- tive but was not recommended. The patients ranged in age from 3 to 20 years (mean age 12.8 years). Demographic and clinical data are summarized in Table 1. Surgical Technique Each patient underwent a biopsy procedure in which a stereotactic frame (CRW system; Radionics, Inc., Burling- ton, MA) and a Nashold biopsy needle were used to estab- lish a definitive diagnosis of the brainstem mass. Biopsy sampling was performed using a computer graphics work- station, which allowed for trajectory visualization in the co- ronal, sagittal, axial, and probe planes. 23 The center of the lesion was targeted via one of the following approaches: midbrain and pontine lesions located above the middle cer- ebellar peduncle were targeted via a transfrontal trajectory, and middle or low pontine lesions were targeted through the cerebellum and middle cerebellar peduncle. Study Methods Approval for this study was obtained from the Universi- ty of Florida’s Institutional Review Board. We conducted a retrospective review of each patient’s medical records for Brainstem stereotactic biopsy sampling in children DAVID W. PINCUS, M.D., PH.D., ERICH O. RICHTER, M.D., ANTHONY T. Y ACHNIS, M.D., JEFFREY BENNETT , M.D., M. T ARIQ BHATTI, M.D., AND AMY SMITH, M.D. Departments of Neurosurgery, Ophthalmology, Pediatrics, Pathology, Neurology, and Radiology, University of Florida, Gainesville, Florida Object. Although it is widely accepted that biopsy sampling is not indicated for the diagnosis and empiric treat- ment of diffuse pontine glioma, it is common to encounter patients with brainstem lesions that cannot be diagnosed on the basis of imaging studies alone. In cases not amenable to resection, a tissue diagnosis may still be necessary to make appropriate treatment recommendations. The authors retrospectively reviewed their institutional experience with stereotactic biopsy procedures in pediatric patients during a 4-year period. Methods. A three-dimensional graphics workstation was used for trajectory planning to obtain biopsy samples of brainstem lesions in 10 patients. One patient experienced mild diplopia postoperatively. No other morbidity was noted; no patient died as a result of the procedure. The biopsy procedure yielded a pathological diagnosis in all cases. A later resection in one patient resulted in a change in diagnosis. Overall, the pathological findings were var- ied, and in some cases the tissue diagnosis altered the treatment recommendations. Conclusions. The findings in this small series suggest that brainstem stereotactic biopsy sampling in children is a safe procedure with a high diagnostic yield. In patients in whom radiographic findings are not consistent with dif- fuse pontine glioma and resection is not appropriate, stereotactic biopsy sampling should be considered. KEY WORDS • stereotactic biopsy sampling • glioma • pediatric neurosurgery A Abbreviations used in this paper: GBM = glioblastoma multi- forme; MR = magnetic resonance; WHO = World Health Organi- zation.