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.

Retrospective review of a venous sparing approach to resection of parasagittal meningiomas.

Parasagittal meningiomas make up 20-30% of intracranial meningiomas. Their proximity to, and often invasion of, the superior sagittal sinus (SSS) may preclude complete surgical resection. Repair and reconstruction of the SSS in pursuit of Simpson grade I resection is associated with increased morbidity. We retrospectively reviewed 76 parasagittal meningiomas. Our surgical technique emphasized preservation of bridging cortical veins and the SSS. In cases where the SSS was already occluded by tumor, this portion of the sinus and adjacent falx were resected. In cases where the SSS was not occluded by tumor, maximal tumor resection without entering the SSS was performed. The post-op neurologic exam was unchanged or improved in 91% of patients. Only one patient (1%) experienced new persistent neurologic symptoms, which consisted of contralateral numbness. Sixteen patients (21%) experienced tumor recurrence that was deemed appropriate for additional intervention (radiosurgery, re-operation, or re-operation + radiosurgery). Age, sex, location, recurrence, size, presence of edema, degree of sinus involvement, or pathology were not statistically significant predictors of recurrence. Length of follow-up was the only statistically significant predictor of recurrence. A surgical strategy emphasizing preservation of cortical bridging veins and the SSS appears to be safe and effective for the treatment of parasagittal meningiomas. The use of adjuvant therapy for the treatment of residual intrasinusal tumor encountered in this approach may be reserved for cases of tumor progression.

Repair of Temporal Bone Defects via the Middle Cranial Fossa Approach: Treatment of 2 Pathologies With 1 Operation.

BACKGROUND: Temporal bone dehiscence (TBD) often results in leakage of cerebrospinal fluid (CSF) and/or encephalocele. TBD can also occur over the superior semicircular canal, causing debilitating vertigo. Both can be repaired surgically, but traditional treatment is focused only on one pathology, not both. OBJECTIVE: To report our experience in the treatment of TBD via the middle cranial fossa (MCF) approach. METHODS: A retrospective review was conducted for all patients who underwent MCF approach for surgical repair of any temporal fossa dehiscence. RESULTS: A total of 34 patients underwent a total of 37 surgeries. Obesity was prevalent; 21 patients (61.8%) were obese (BMI [body mass index] > 30 kg/m2), and 7 (20.6%) were overweight (BMI 25-30 kg/m2). The most common presenting symptom was hearing disturbance (70.3%), followed by otorrhea (51.4%). Empty sella was noted on computed tomography or magnetic resonance imaging in 15 patients (45.5%). Eight of the 34 patients (23.5%) were found to have superior semicircular canal dehiscence (SCD). Hearing improved with surgical intervention in 25 of 26 patients with hearing loss as a presenting symptom (96%). CSF resolved in 18 of 19 cases (95%). Seventy-three percent of patients reported at least minimal improvement in vertigo. CONCLUSION: TBD may present with symptoms of CSF leak/encephalocele, but may also present with superior SCD. We recommend consistent review of the temporal bone imaging to check for superior SCD, and repair of the SCD first to prevent complications involving the labyrinth and cochlea. MCF approach using a multilayer repair without a lumbar drain is highly effective with minimal risk of complications.

Deep brain stimulation with a pre-existing cochlear implant: Surgical technique and outcome.

BACKGROUND: Patients with previously implanted cranial devices pose a special challenge in deep brain stimulation (DBS) surgery. We report the implantation of bilateral DBS leads in a patient with a cochlear implant. Technical nuances and long-term interdevice functionality are presented. CASE DESCRIPTION: A 70-year-old patient with advancing Parkinson's disease and a previously placed cochlear implant for sensorineural hearing loss was referred for placement of bilateral DBS in the subthalamic nucleus (STN). Prior to DBS, the patient underwent surgical removal of the subgaleal cochlear magnet, followed by stereotactic MRI, frame placement, stereotactic computed tomography (CT), and merging of imaging studies. This technique allowed for successful computational merging, MRI-guided targeting, and lead implantation with acceptable accuracy. Formal testing and programming of both the devices were successful without electrical interference. CONCLUSION: Successful DBS implantation with high resolution MRI-guided targeting is technically feasible in patients with previously implanted cochlear implants by following proper precautions.

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.

Identification of the stria medullaris thalami using diffusion tensor imaging.

BACKGROUND: Deep brain stimulation (DBS) via anatomical targeting of white matter tracts defined by diffusion tensor imaging (DTI) may be a useful tool in the treatment of pathologic neurophysiologic circuits implicated in certain disease states like treatment resistant depression (TRD). We sought to determine if DTI could be used to define the stria medullaris thalami (SM), the major afferent white matter pathway to the lateral habenula (LHb), a thalamic nucleus implicated in the pathophysiology of TRD. METHODS: Probabilistic DTI was performed on ten cerebral hemispheres in five patients who underwent preoperative MRI for DBS surgery. Manual identification of the LHb on axial T1 weighted MRI was used for the initial seed region for tractography. Variations in tractography depending on chosen axial slice of the LHb and chosen voxel within the LHb were also assessed. RESULTS: In all hemispheres the SM was reliably visualized. Variations in chosen axial seed slice as well as variations in single seed placement did not lead to significant changes in SM tractography. CONCLUSIONS: Probabilistic DTI can be used to visualize the SM which may ultimately provide utility for direct anatomic targeting in DBS surgery.