Gadolinium enhancement of cranial nerves: Implications for interstitial fluid drainage from brainstem into cranial nerves in humans

Drainage of interstitial fluid and solutes from the brainstem has not been well studied. To map one drainage pathway in the human brainstem, we took advantage of the focal blood–brain barrier disruption occurring in a multiple sclerosis brainstem lesion, coupled with intravenous injection of gadolinium, which simulates an intraparenchymal injection of gadolinium tracer within the restricted confines of this small brain region. Using high-resolution MRI, we show how it is possible for interstitial fluid to drain into the adjacent trigeminal and oculomotor nerves, in keeping with a pathway of communication between the extracellular spaces of the brainstem and cranial nerve parenchyma.

Tumor control and trigeminal dysfunction improvement after stereotactic radiosurgery for trigeminal schwannomas: a systematic review and meta-analysis

Trigeminal nerve schwannomas (TS) are uncommon intracranial tumors, frequently presenting with debilitating trigeminal and/or oculomotor nerve dysfunction. While surgical resection has been described, its morbidity and mortality rates are non-negligible. Stereotactic radiosurgery (SRS) has emerged with variable results as a valuable alternative. Here, we aimed at reviewing the medical literature on TS treated with SRS so as to investigate rates of tumor control and symptomatic improvement. We reviewed manuscripts published between January 1990 and December 2019 on PubMed. Tumor control and symptomatic improvement rates were evaluated with separate meta-analyses. This meta-analysis included 18 studies comprising a total of 564 patients. Among them, only one reported the outcomes of linear accelerators (Linac), while the others of GK. Tumor control rates after SRS were 92.3% (range 90.1–94.5; p < 0.001), and tumor decrease rates were 62.7% (range 54.3–71, p < 0.001). Tumor progression rates were 9.4% (range 6.8–11.9, p < 0.001). Clinical improvement rates of trigeminal neuralgia were 63.5% (52.9–74.1, p < 0.001) and of oculomotor nerves were 48.2% (range 36–60.5, p < 0.001). Clinical worsening rate was 10.7% (range 7.6–13.8, p < 0.001). Stereotactic radiosurgery for TS is associated with high tumor control rates and favorable clinical outcomes, especially for trigeminal neuralgia and oculomotor nerves. However, patients should be correctly advised about the risk of tumor progression and potential clinical worsening. Future clinical studies should focus on standard reporting of clinical outcomes.

Isolated hypoglossal mononeuropathy associated with preeclampsia

Cranial mononeuropathies are unusual manifestations of preeclampsia. Facial and oculomotor nerves are the most affected. Brain MRI is necessary to exclude alternative diagnoses. There are no specific treatments except the management of preeclampsia. The prognosis is usually good.

Morphometric study of the meningeal sheath of the oculo motor nerve in the latero-sellar lodge: Neuro surgical interest

The meningeal sheath of the oculomotor nerve is also known that the latero-sellar lodge. It has both dural and extra-dural components. This sheath contains vascular elements including the carotid and nervous siphon, the motor nerves of the eye to which are added the division branches V1 and V2 of the trigeminal nerve. The oculomotor nerve runs through this lodge wrapped in its meningeal sheath. The purpose of this study was to document the dimensions of the different segments of the nerve as it crosses the lodge. Eight pairs of lodges were the subject of this study. Dead bodies fixed with 10% formalin for two to three weeks underwent a craniotomy. After removal of the brain, nerve III and its meningeal envelope were dissected and exposed. The different segments of the nerve were measured in both sides. The entrance orifice of the porus of the oculomotor nerve III was located behind the anterior clinoid process to 7.2 mm (extreme from 3 to 13mm) on the right and to 7.40mm (extreme from 4 to 12) on the left. The meningeal cul-de-sac represented the intra-conical segment and was either 5.2mm long (extreme from 4 to 6.5mm) or short 3.25mm (extreme from 2 to 3.5mm). The supra-cavernous segment measured on the right 5.2 mm (extreme from 2 to 8 mm) and on the left 4.6 mm (extreme from 3 to 7 mm). The latero-sellar lodge, a complex and narrowed region is crossed by nervous elements each in its meningeal sheath. This deserves an approach by surgical microdissection. Key words: Oculomotor nerves - meningeal cone - measurement – cadaver – latero-sellar lodge.

Combined Extradural and Intradural Pterional Transzygomatic Approach to Large Sphenoid Wing Meningiomas. Operative Technique and Surgical Results

Objectives Describe a unique and safe surgical procedure for the microsurgical management of large sphenoid wing meningiomas (SWMs) aimed to a radical resection of these tumors. Design A prospective series of 26 cases with SWMs larger than 3 cm in one of its main diameter is presented. All patients were studied following the same clinical and imaging procedures. The surgical approach was through a pterional transzygomatic craniotomy. The surgical procedure has the following steps: 1. Extradural tumor devascularization and resection of the hyperostotic and/or infiltrated bone and then intradurally; 2. Intradural tumor debunking; 3. Microdissection of vascular branches and perforators from the capsule; 4. Identification of the optic and oculomotor nerves and internal carotid artery; 5. Tumor capsule dissection and resection; 6. Dural resection or cauterization; 7. Dural and bone reconstruction and closing. Results All lesions were completely removed. Most complications were transient. The most relevant complication was a large middle cerebral artery infarct with permanent hemiplegia despite a decompressive craniotomy. Conclusion Large SWMs can be considered as a single pathology regarding the surgical approach and intraoperative microsurgical procedure strategies. The pterional transzygomatic approach allows an extradural devascularization of the tumor and an extensive bone resection that facilitates the intradural stage of tumor resection. The proposed approach allows a wide and radical resection of the duramater and bone that increases the Simpson grade. However, surgery does not control other biological or molecular prognostic factors involved in tumor recurrence.