Surgical approaches for brainstem tumors in pediatric patients.

PURPOSE: To analyze the pathways to brainstem tumors in childhood, as well as safe entry zones. METHOD: We conducted a retrospective study of 207 patients less than 18 years old who underwent brainstem tumor resection by the first author (Cavalheiro, S.) at the Neurosurgical Service and Pediatric Oncology Institute of the São Paulo Federal University from 1991 to 2011. RESULTS: Brainstem tumors corresponded to 9.1 % of all pediatric tumors operated in that same period. Eleven previously described "safe entry zones" were used. We describe a new safe zone located in the superior ventral pons, which we named supratrigeminal approach. The operative mortality seen in the first 2 months after surgery was 1.9 % (four patients), and the morbidity rate was 21.2 %. CONCLUSIONS: Anatomic knowledge of intrinsic and extrinsic brainstem structures, in association with a refined neurosurgical technique assisted by intraoperative monitoring, and surgical planning based on magnetic resonance imaging (MRI) and tractography have allowed for wide resection of brainstem lesions with low mortality and acceptable morbidity rates.

Single-shot T1 mapping of the corpus callosum: a rapid characterization of fiber bundle anatomy.

Using diffusion-tensor magnetic resonance imaging and fiber tractography the topographic organization of the human corpus callosum (CC) has been described to comprise five segments with fibers projecting into prefrontal (I), premotor and supplementary motor (II), primary motor (III), and primary sensory areas (IV), as well as into parietal, temporal, and occipital cortical areas (V). In order to more rapidly characterize the underlying anatomy of these segments, this study used a novel single-shot T1 mapping method to quantitatively determine T1 relaxation times in the human CC. A region-of-interest analysis revealed a tendency for the lowest T1 relaxation times in the genu and the highest T1 relaxation times in the somatomotor region of the CC. This observation separates regions dominated by myelinated fibers with large diameters (somatomotor area) from densely packed smaller axonal bundles (genu) with less myelin. The results indicate that characteristic T1 relaxation times in callosal profiles provide an additional means to monitor differences in fiber anatomy, fiber density, and gray matter in respective neocortical areas. In conclusion, rapid T1 mapping allows for a characterization of the axonal architecture in an individual CC in less than 10 s. The approach emerges as a valuable means for studying neocortical brain anatomy with possible implications for the diagnosis of neurodegenerative processes.

Applied microanatomy of cervical nerve and its related structure / 第三军医大学学报

Objective To study the course of different cervical nerve segments and their related intervertebral foramen’s size so as to increase safety and decrease complications in microinvasive surgery for cervical syndrome. Methods Fifteen human cervical specimens (30 sides) were anatomically observed for the course, branches and distribution of cervical nerves. Results The diameter of intervertebral foramen ranges from 0.54 to 0.65 cm, and increases gradually from top to bottom. The vertical diameter and anteroposterior diameter between C4, C5 and C6 vertebrae are smaller, and those between C3 and C7 are larger, but the diameter line of nerve root in intervertebral foramen from up to down gradually increases. The anteversion angle between nerve root and spine cord on horizontal plane is from 15? to 19?, within a small variation, while the declination angle on coronal plane gradually decreases from C3 to C7. There exist plenty of anastomosis branches among the cervical dorsal rami. Conclusion In the range of 0.6 cm around articular process at the entrance of intervertebral foramen, it is the narrowest part, the removal of which may alleviate the pressure on nerve root and benefit spinal stability. Because of the general existence of anastomosis branches of cervical nerve, the symptoms of cervical syndrome are not completely consistent to innervation. The intervertebral foramen between C4, C5, C6 is relatively small and the diameter line of nerve root is comparatively large, so the nerve root at C4, C5, C6 is most likely to be pressed.