Microsurgical anatomic features of the lamina terminalis

Morphological evaluation of the normal and hydrocephalic third ventricle on cranial magnetic resonance imaging in children: a retrospective study

BACKGROUND

Third ventricle morphological changes reflect changes in the ventricular system in pediatric hydrocephalus, so visual inspection of the third ventricle shape is standard practice. However, normal pediatric reference data are not available.

OBJECTIVE

To investigate both the normal development of the third ventricle in the 0-18-year age group and changes in its biometry due to hydrocephalus.

MATERIALS AND METHODS

For this retrospective study, we selected individuals ages 0-18 years who had magnetic resonance imaging (MRI) from 2012 to 2020. We included 700 children (331 girls) who had three-dimensional (3-D) T1-weighted sequences without and 25 with hydrocephalus (11 girls). We measured the distances between the anatomical structures limiting the third ventricle by dividing the third ventricle into anterior and posterior regions. We made seven linear measurements and three index calculations using 3DSlicer and MRICloud pipeline, and we analyzed the results of 23 age groups in normal and hydrocephalic patients using SPSS (v. 23).

RESULTS

Salient findings are: (1) The posterior part of the third ventricle is more affected by both developmental and hydrocephalus-related changes. (2) For third ventricle measurements, gender was insignificant while age was significant. (3) Normal third ventricular volumetric development showed a segmental increase in the 0-18 age range. The hydrocephalic third ventricle volume cut-off value in this age group was 3 cm³.

CONCLUSION

This study describes third ventricle morphometry using a linear measurement method. The ratios defined in the midsagittal plane were clinically useful for diagnosing the hydrocephalic third ventricle. The linear and volumetric reference data and ratios are expected to help increase diagnostic accuracy in distinguishing normal and hydrocephalic third ventricles.

Interoptic, Trans-lamina Terminalis, Opticocarotid Triangle, and Caroticosylvian Windows From Mini-Supraorbital, Frontomedial, and Pterional Perspectives: A Comparative Cadaver Study With Artificial Lesions

Introduction: The mini-supraorbital (MSO) and pterional (PT) approaches have been compared in a number of studies focusing on the treatment of aneurysms, craniopharyngiomas, and meningiomas. The goal of this study was to analyze the surgical exposure to different artificial lesions through interoptic (IO), trans-lamina terminalis (TLT), opticocarotid triangle (OCT), and caroticosylvian (CS) windows from the MSO, frontomedial (FM), and PT perspectives. Methods: The MSO, PT, and FM approaches were performed sequentially in two fixed cadaver heads. Three colored spheres were placed around the optic chiasm: (1) between the optic nerves; (2) between the optic nerve and the internal carotid artery; and (3) between the internal carotid artery and the oculomotor nerve. The surgical exposures to these structures by using the IO, TLT, OCT, and CS windows were compared. Results: (1) IO window: from the MSO and PT approaches, the total surgical exposure mainly allows visualization of contralateral lesions. The FM approach was superior for exploration of both sides of the area between the optic nerves. (2) TLT pathway: the MSO and PT approaches mainly expose the contralateral third ventricle wall. (3) OCT window: the PT approach allows exposure of a larger part of the sphere between the optic nerve and the internal carotid artery than the MSO approach. (4) CS window: the PT approach allows a better exposure of lateral structures such as the oculomotor nerve and of the medial prepontine area in comparison to the MSO approach. Conclusion: Simulation of the surgical situation with artificial lesions is a good model for comparing surgical perspectives and for analyzing feasibility of lesion exposure and resection.

Anterior communicating artery division in the endoscopic endonasal translamina terminalis approach to the third ventricle: an anatomical feasibility study

BACKGROUND

Endonasal endoscopic approaches (EEA) to the third ventricle are well described but generally use an infrachiasmatic route since the suprachiasmatic translamina terminalis corridor is blocked by the anterior communicating artery (AComA). The bifrontal basal interhemispheric translamina terminalis approach has been facilitated with transection of the AComA. The aim of the study is to describe the anatomical feasibility and limitations of the EEA translamina terminalis approach to the third ventricle augmented with AComA surgical ligation.

METHODS

Endoscopic dissections were performed on five cadaveric heads injected with colored latex using rod lens endoscopes attached to a high-definition camera and a digital video recorder system. A stepwise anatomical dissection of the endoscopic endonasal transtuberculum, transplanum, translamina terminalis approach to the third ventricle was performed. Measurements were performed before and after AComA elevation and transection using a millimeter flexible caliper.

RESULTS

Multiple comparison statistical analysis revealed a statistically significant difference in vertical exposure between the control condition and after AComA elevation, between the control condition and after AComA division and between the AComA elevation and division (p < 0.05). The mean difference in exposed surgical area was statistically significant between the control and after AComA division and between elevation and AComA division (p < 0.01), whereas it was not statistically significant between the control condition and AComA elevation (NS).

CONCLUSION

The anatomical feasibility of clipping and dividing the AComA through an EEA has been demonstrated in all the cadaveric specimens. The approach facilitates exposure of the suprachiasmatic optic recess within the third ventricle that may be a blind spot during an infrachiasmatic approach.

Radical resection of a craniopharyngioma via the extradural anterior temporal approach with zygomatic arch osteotomy

BACKGROUND

Though the extradural anterior temporal approach (EDATA) with zygomatic osteotomy is useful, there are only few reports of this approach being used for craniopharyngioma resection. Herein, we report our surgical case series and the technical importance of EDATA for the radical removal of a craniopharyngioma.

METHODS

We report 7 cases of craniopharyngiomas treated surgically between April 1999 and October 2015. The surgical approaches, clinical presentation, pre and postoperative radiographic examination results, surgical outcomes, and morbidity were analyzed.

RESULTS

The mean follow-up period was 89.1 months. The surgical approach was EDATA with zygomatic osteotomy in 4, combined interhemispheric translamina terminalis approach (IHTLA) and trans-sylvian anterior temporal approach (ATA) in 2, and IHTLA in 1 patient. Complete tumor resection was achieved in all cases, without any recurrence during the follow-up period. Transient morbidities were oculomotor nerve palsy in 2, and meningitis and hydrocephalus in 1 patient. There was 1 case of permanent morbidity due to hydrocephalus that needed a ventriculoperitoneal shunt, and 1 case of blindness on the operative side. Visual acuity and visual field improved in 4 cases, showed no change in 2 cases, and deteriorated in 1 case. Though the pituitary stalk was preserved in 2 cases, all 7 cases needed total hormone replacement therapy.

CONCLUSION

EDATA with zygomatic osteotomy ensures sufficient mobility of the internal carotid artery, and provides a good lateral and look up operative view. Hence, it can be used effectively for radical resection of craniopharyngiomas through the opticocarotid space and retrocarotid space.

The chiasmatic recess of the third ventricle: delineation with magnetic resonance imaging

PURPOSE

The chiasmatic recess (CR) is a small, downward extension in the most rostral third ventricle. Few studies have highlighted its morphology. Accordingly, we explored the CR using magnetic resonance imaging.

METHODS

A total of 104 patients were enrolled in this study. Magnetic resonance imaging examinations were performed in axial and sagittal sections. Imaging data were obtained as thin-sliced, seamless sections.

RESULTS

The CR was clearly identified in 98 % of axial and 96 % of sagittal sections. The lamina terminalis was delineated as a membranous structure with homogenous thickness. The CR was consistently delineated as a smoothly tapering, cerebrospinal fluid-filled space. The number of axial images required to encompass the entire CR was 1 slice for 1.9 % of samples, 2 for 32.7 %, 3 for 49 %, 4 for 12.5 %, 5 for 1 %, and 6 for 1 %. On axial view, the CR generally presented as a long horizontal ellipse. On sagittal view, the CR showed variable shape and length. The optic chiasm-lamina terminalis angle, formed by the upper surface of the optic chiasm and inner surface of the lamina terminalis and measured on midsagittal sections, showed considerable variability.

CONCLUSIONS

The CR is a hollow structure with various contours. Recognition of the morphological characteristics of the CR and lamina terminalis may be helpful for safe perforation of the lamina terminalis. Magnetic resonance imaging is useful for exploring the CR.

A case of transient hypothermia after trans-lamina terminalis and third ventricle clipping of an extremely high-position basilar tip aneurysm

Reports on the trans-lamina terminalis and trans-third ventricular approach are rare. The risk associated with this approach is unknown. After an unsuccessful endovascular surgery, we performed direct surgical clipping via the third ventricle on a 78-year-old woman presenting with an extremely high-positioned, ruptured basilar tip aneurysm. She experienced transient hypothermia for 5 days, and it was considered that this was due to hypothalamic dysfunction. It is necessary to recognize that there is the potential for hypothermia after surgery via the lamina terminalis and third ventricle, even though the mechanisms of hypothalamic thermoregulation are still unclear.