Optic Tract as an Upper Limit in Amygdalectomy: Microsurgical Study.

BACKGROUND: In surgeries involving resection of the amygdala, despite clear relations established with the medial, lateral, anterior, posterior, and inferior segments, the upper limit remains controversial. The optic tract (OT) has been anatomically considered as a good landmark immediately inferior to the striatopallidal region. This anatomic structure has barely been explored by microsurgical study, generating uncertainty about the exact relationship with the surrounding structures. OBJECTIVE: To describe the OT in its entire length through microsurgical study, showing its superior, inferior, medial, and lateral relationships and highlighting its value as a landmark in superior amygdala resection. METHODS: Microsurgical anatomic dissection of the OT, from its origin in the chiasm to the lateral geniculate nucleus was performed in 8 alcohol-fixed human hemispheres, showing its different segments and relations. Photographs were taken from different angles to facilitate surgical orientation. RESULTS: We performed a dissection of the OT, showing its position relative to caudate and hippocampal formations. We exposed the structures related to the OT superiorly (striatopallidal region and superior caudate fasciculus), inferiorly (head of the hippocampus, amygdala, anterior choroidal artery, perforating artery branch of the anterior choroidal artery, terminal stria, and basal vein), medially (internal capsule and midbrain), and laterally (temporal stem [uncinate and inferior fronto-occipital fascicle], anterior perforated substance, and superior caudate fasciculus). CONCLUSION: To date, there is a paucity of articles describing the anatomy of the OT from a neurosurgery perspective. In this study, we describe the microsurgical anatomic path of the OT, as a reliable upper limit landmark for amygdala resection.

Selection and Prognosis of Optic Canal Decompression for Traumatic Optic Neuropathy.

OBJECTIVE: To comprehensively compare the vision improvement rate in patients with traumatic optic neuropathy with different surgical timing and other different preoperative conditions. METHODS: PubMed, Embase, and MEDLINE Ovid were searched to identify studies. We performed subgroup analyses for differences in the surgical timing, surgical approach, optic canal fractures, state of consciousness after trauma, time of visual loss development, incision of the optic nerve sheath, and treatment methods. RESULTS: A total of 74 studies involving 6084 patients were included in the final analysis. In the groups of patients with early (≤3 days), middle (4-7 days), and late (>7 days) surgical interventions, 58.4%, 53.2%, and 45.4% demonstrated visual improvements, respectively. The results of the statistical analysis revealed that patients with early surgical intervention had a higher improvement rate than patients with late surgical intervention (P = 0.00953). The improvement rate was significantly lower for patients who presented with no light perception before surgery than for patients whose vision was better than no light perception (relative risk, 0.498; 95% confidence interval [CI], 0.443-0.561; P = 0.001) and lower for patients with immediate visual loss after trauma than for those with secondary visual loss (relative risk, 0.639; 95% CI, 0.498-0.819; P = 0.001). CONCLUSIONS: We recommend that patients seek medical treatment as soon as possible after traumatic optic nerve injury, and patients with secondary injuries can have a good recovery effect while still living with light perception or more. The option of treatment and whether to incise the optic nerve sheath still remains controversial.

Suprasellar Hemangioblastoma with Reversible Edema-Like Change Along the Optic Tract: A Case Report and Literature Review.

BACKGROUND: Hemangioblastomas usually occur in the cerebellum and are often a component of von Hippel-Lindau disease. Edema-like changes along the optic tract are commonly observed in association with tumors in the sellar and suprasellar regions, such as craniopharyngiomas and pituitary adenomas. Here, we describe a case of sporadic suprasellar hemangioblastoma with edema-like changes along the optic tract that completely resolved after surgery. CASE DESCRIPTION: The patient was a 28-year-old woman with failing vision and a bitemporal hemianopia. Magnetic resonance imaging revealed a tumor accompanied by a 10-mm cyst. Fluid-attenuated inversion recovery axial magnetic resonance imaging revealed a hyperintense region along the optic tract. Other regions of the central nervous system were normal. Endoscopic transsphenoidal surgery was performed, and the histopathologic findings confirmed hemangioblastoma. Six months after surgery, the edema-like change along the optic tract had disappeared. The patient is doing well without pituitary insufficiency, pituitary hormone medications, or signs of tumor recurrence. In addition, the genetic test was negative for von Hippel-Lindau mutations. CONCLUSIONS: When examining a patient with suprasellar tumor, clinicians must consider the possibility of hemangioblastoma. Adequate treatment can improve the edematous change and visual disturbance.

Endoscopic Endonasal Approach to the Optic Canal: Anatomic Considerations and Surgical Relevance.

BACKGROUND: Increasing use of endoscopic endonasal surgery for suprasellar lesions with extension into the optic canal (OC) has necessitated a better endonasal description of the OC. OBJECTIVE: To identify the osseous OC transcranially and then investigate its anatomic relationship to the key endonasal intrasphenoidal landmarks. We also aimed to determine and describe the technical nuances for safely opening the falciform ligament and intracanalicular dura (surrounding the optic nerve [ON]) endonasally. METHODS: Ten fresh human head silicon-injected specimens underwent an endoscopic transtuberculum/transplanum approach followed by 2-piece orbitozygomatic craniotomy to allow identification of 20 OCs. After completing up to 270° of endonasal bony decompression of the OC, a dural incision started at the sella and continued superiorly across the superior intercavernous sinus. Subsequently the dural opening was extended anterolaterally across the dura of the prechiasmatic sulcus, limbus sphenoidale, and planum. RESULTS: Endonasally, the length of the osseous OC was approximately 6 mm and equivalent to the length of the lateral opticocarotid recess, as measured anteroposteriorly. The ophthalmic artery arose from the supraclinoidal carotid artery at approximately 2.5 mm from the medial osseous OC entrance. Transcranial correlation of the endonasal dural incision confirmed medial detachment of the falciform ligament and exposure of the preforaminal ON. CONCLUSION: The lateral opticocarotid recess allows distinction of the preforaminal ON, roofed by the falciform ligament from the intracanalicular segment in the osseous OC. This facilitates the preoperative surgical strategy regarding the extent of OC decompression and dural opening. Extensive endonasal decompression of the OC and division of the falciform ligament is feasible.