Pediatric pineal region tumors: institutional experience of surgical managements with posterior interhemispheric transtentorial approach

Abstract

Purpose: Resecting pineal region tumors in children is often challenging. Several approaches have been proposed and practiced. A personal series of pediatric pineal region tumors resected through craniotomy with posterior interhemispheric occipital transtentorial (OT) approach are reviewed. We present the surgical techniques, pitfalls, and their results.

Material and methods: Eighty patients ranging in age from 3 months to 21 years old, and treated over 3 decades were reviewed. Hydrocephalus caused the main presenting symptoms and was noted in 74 patients. It was treated prior to the craniotomy for tumor resection with endoscopic third ventriculostomy (ETV) in 33, external ventricular drainage in 26, and precraniotomy shunt in 15. Nine patients had ETV together with endoscopic biopsy. All patients had a parieto-occipital craniotomy in a prone position. Through a tentorial section, a gross total resection of the tumor was attempted except for germinomas.

Results: The tumor pathology showed 32 germ cell tumors (GCT), 22 benign astrocytomas, 13 pineal parenchymal tumors, 5 ATRTs, 3 papillary tumors, and 5 others. Of GCTs, 18 were teratomas. The extent of resection consisted of 55 gross total resections, 13 subtotal resections, 10 partial, and 2 biopsies with one postoperative death. Hemiparesis in 2, cerebellar ataxia in another 2, and hemiballismus in 1 were transient and improved over time. One had permanent hemisensory loss and another patient had bilateral oculomotor palsy. Postoperative homonymous hemianopia occurred in 2 patients but subsided over a short period of time. Parinaud's sign was noted in 24 patients, of which 16 were transient.

Conclusion: The posterior interhemispheric OT approach provides a safe route and comfortable access to the pineal region in children. A great majority of postoperative neurological complications are the results of direct manipulations of the midbrain at tumor resection. Identification and preservation of the tumor-brain interface are of paramount importance. GCTs other than teratomas are treated with neoadjuvant chemotherapy and may eliminate the need for craniotomy. Exophytic midbrain JPAs are amenable to resection.

Keywords: Germ cell tumor; Hydrocephalus headings: pineal region tumors; Midbrain glioma; Neuroendoscopy; Occipital transtentorial resection; Pineal tumor; Pineoblastoma; Superior medullary velum.

Fig. 1

Surgical photograph of exposed left parieto-occipital lobe. The last cortical bridging vein at the entry site to the superior sagittal sinus is protected with a cottonoid pledget (arrow)

Fig. 2

Surgical photo showing the tentorial opening. The tentorium is sectioned (A) and the arachnoid membrane is open (B), showing the vein of Galen and its tributaries. Note a thick arachnoid membrane (arach) over the tectum. (SS: straight sinus, ICN: internal occipital vein, Occ: occipital lobe, cc: corpus callosum, vG: vein of Galen, ICV: internal cerebral vein)

Fig. 3

A 10-year-old male with pineal teratoma. Contrast-enhanced MR, axial (a), and sagittal (b), showing a mass partly protruding to the quadrigeminal cistern. Surgical photo showing the pineal teratoma protruding under the vein of Galen (A) and postresection photo through the third ventricle (B). (vG: vein of Galen, cc: corpus callosum, SS: straight sinus)

Fig. 4

Mid-sagittal postcontrast MR of a 13-year-old male with predominantly intra-third ventricle teratoma. Surgical photo, before (A) and after (B) exploring the tumor capsule between the vein of Galen and the tectum. (cc: corpus callosum, vG: vein of Galen, T: tumor)

Fig. 5

A 5-year-old girl with exophytic tectal JPA. Post-contrast MR images, before (A axial, B sagittal) and after (C axial, D sagittal) resection show a heterogeneously enhancing tumor extending to the quadrigeminal cistern. Surgical photo showing a view of an exophytic tumor through the tentorial opening (cc: corpus callosum, vG: vein of Gallen, Ce: cerebellar vermis)

Fig. 6

Tegmentum to posterior thalamus JPA. Postcontrast MR before (a, b) and after (c, d) tumor resection. Intraoperative photography (A) through the left tentorial section shows expanding dorsolateral midbrain (dotted arrow) just next to the vein of Galen (solid arrow). Note tumor-brain interface (arrow) through tumor resected cavity (B)

Fig. 7

A 13-month-old male with ATRT of the SMV. Post-contrast MR before (A axial, B sagittal) and after (C axial, D sagittal) resection through left occipital transtentorial resection. Note the tumor extending to the foramen of Magendie through the IV ventricle. Surgical photo showing a tumor exposed through a tentorial opening (cc: corpus callosum)

Fig. 8

A case of growing teratoma. An 11-year-old boy with an inhomogeneous mass in the posterior third ventricle on T2 weighted MR, sagittal (A), and axila (B) images. He had elevated AFP (264 ng/mL in serum and 7.0 in the CSF). The following chemotherapy 3 months after neoadjuvant chemotherapy, AFP titer became normalized but the tumor continued to increase on T2 weighted MR, sagittal (C), and axila (D) images. A mature teratoma was resected on a second-look surgery

Fig. 9

Post-contrast MR, sagittal (A), and axial (B) images show an enhancing large JPA extending from the posterior third ventricle to the bilateral thalamus. The tegmentum and tectum of the midbrain are obscure. Postresection of JPA, MRI, sagittal (C), and axial (D) images showing resolution of the tumor mass and re-appearance of the compressed midbrain. The tumor appeared to arise from the right posterior thalamus extending to the third ventricle