Anatomical Predictors of Transcranial Surgical Access to the Suprasellar Space

Objective  The suprasellar space is a common location for intracranial lesions. The position of the optic chiasm (prefixed vs. postfixed) results in variable sizes of operative corridors and is thus important to identify when choosing a surgical approach to this region. In this study, we aim to identify relationships between suprasellar anatomy and external cranial metrics to guide in preoperative planning. Methods  T2-weighted magnetic resonance images (MRIs) from 50 patients (25 males and 25 females) were analyzed. Various intracranial and extracranial metrics were measured. Statistical analysis was performed to determine any associations between metrics. Results  Interoptic space (IOS) size correlated with interpupillary distance (IPD; a  = 7.3, 95% confidence interval [CI] = 4.5-10.0, R ²  = 0.3708, p  = 0.0009). IOS size also correlated with fixation of the optic chiasm, for prefixed chiasms ( n  = 7), the mean IOS is 205.14 mm ² , for normal chiasm position ( n  = 33) the mean IOS is 216.94 mm ² and for postfixed chiasms ( n  = 10) the mean IOS is 236.20 mm ² ( p  = 0.002). IPD correlates with optic nerve distance (OND; p  = 0.1534). Cranial index does not predict OND, IPD, or IOS. Conclusion  This study provides insight into relationships between intracranial structures and extracranial metrics. This is the first study to describe a statistically significant correlation between IPD and IOS. Surgical approach can be guided in part by the size of the IOS and its correlates. Particularly small intraoptic space may guide the surgeon away from a subfrontal approach.

Surgical Resection of Clinoidal Meningiomas without Routine Use of Clinoidectomy

OBJECTIVE

Meningiomas of the anterior clinoid process (ACP) present significant surgical challenges given their anatomic relation to critical neurovascular structures. Routine anterior clinoidectomy is often described as a critical step in the resection of these tumors to reduce recurrence and improve visual outcomes. Anterior clinoidectomy, however, is not without risk and its benefits have not been clearly delineated. We present the outcomes of our series of surgically managed ACP meningiomas in which an anterior clinoidectomy was not routinely employed.

METHODS

A retrospective review of all ACP meningiomas operated on between August 1997 and March 2019 was conducted. Patients with a recurrent tumor or with <6 months of follow-up were excluded. Resection was typically carried out via a frontotemporal craniotomy followed by intradural removal of the tumor. Anterior clinoidectomy was only performed if hyperostosis of the ACP caused mass effect on the optic nerve.

RESULTS

Twenty-nine patients were included in this study. Anterior clinoidectomy was performed in 3 patients (10.3%). Gross total resection was achieved in 22 patients (75.9%). Of the 21 patients (72.4%) who presented with visual deficits, vision improved in 18 patients (85.7%) and worsened in 2 (9.5%). Tumor recurrence occurred in 5 patients (17.2%) at a mean follow-up of 64.9 months. Perioperative morbidity was 10.3%. Permanent morbidity and mortality were 6.9% (vision deterioration) and 0%, respectively.

CONCLUSIONS

Resection of ACP meningiomas without routine anterior clinoidectomy minimizes potential risk while achieving gross total resection, recurrence, and visual improvement rates comparable with those in previously reported series.

Spontaneous Otogenic Pneumocephalus: Case Series and Update on Management

Objectives  This study is aimed to report the largest independent case series of spontaneous otogenic pneumocephalus (SOP) and review its pathophysiology, clinical presentation, and treatment. Design  Four patients underwent a middle cranial fossa approach for repair of the tegmen tympani and tegmen mastoideum. A comprehensive review of the literature regarding this disease entity was performed. Setting  U.S. tertiary academic medical center. Participants:  Patients presenting to the lead author's clinic or to the emergency department with radiographic evidence of SOP. Symptoms included headache, otalgia, and neurologic deficits. Main Outcome Measures  Patients were assessed for length of stay, postoperative length of stay, and neurologic outcome. Three of four patients returned to their neurologic baseline following repair. Results  Four patients were successfully managed via a middle cranial fossa approach to repairing the tegmen mastoideum. Conclusion  The middle cranial fossa approach is an effective strategy to repair defects of the tegmen mastoideum. SOP remains a clinically rare disease, with little published information on its diagnosis and treatment.

RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation

Activation of RhoA/Rho kinase leads to growth cone collapse and neurite retraction. Although RhoA/Rho kinase inhibition has been shown to improve axon regeneration, remyelination and functional recovery, its role in neuronal cell death remains unclear. To determine whether RhoA/Rho kinase played a role in neuronal death after injury, we investigated the relationship between RhoA/Rho kinase and cytosolic phospholipase A₂ (cPLA₂), a lipase that mediates inflammation and cell death, using an in vitro neuronal death model and an in vivo contusive spinal cord injury model performed at the 10th thoracic (T10) vertebral level. We found that co-administration of TNF-α and glutamate induced spinal neuron death, and activation of RhoA, Rho kinase and cPLA₂. Inhibition of RhoA, Rho kinase and cPLA₂ significantly reduced TNF-α/glutamate-induced cell death by 33, 52 and 43 %, respectively (p < 0.001). Inhibition of RhoA and Rho kinase also significantly downregulated cPLA₂ activation by 66 and 60 %, respectively (p < 0.01). Furthermore, inhibition of RhoA and Rho kinase reduced the release of arachidonic acid, a downstream substrate of cPLA₂. The immunofluorescence staining showed that ROCK₁ or ROCK₂, two isoforms of Rho kinase, was co-localized with cPLA₂ in neuronal cytoplasm. Interestingly, co-immunoprecipitation (Co-IP) assay showed that ROCK₁ or ROCK₂ bonded directly with cPLA₂ and phospho-cPLA₂. When the Rho kinase inhibitor Y27632 was applied in mice with T10 contusion injury, it significantly decreased cPLA₂ activation and expression and reduced injury-induced apoptosis at and close to the lesion site. Taken together, our results reveal a novel mechanism of RhoA/Rho kinase-mediated neuronal death through regulating cPLA₂ activation.