A computed tomography (CT)-based morphometric study of various skull base parameters and their anatomical relationships relevant to endoscopic endonasal skull base surgery.

Background: Endoscopic skull base surgery requires a thorough understanding of skull base anatomy. Orientation to regional anatomy to avoid complications like internal carotid artery injury can be assisted by knowledge of certain bony landmarks. These landmarks are themselves highly variable structures. This study focuses on the radiological morphometric characterization of these landmarks, which can be of great assistance to surgeons for better planning of endoscopic skull base approaches. Methods: Computed tomography scans of patients without skull base pathologies were analyzed retrospectively for the following parameters - Vidian canal (VC) length, VC and foramen rotundum (FR) distance from midline, the angle between the axis of VC and petrous internal carotid artery (pICA) and between VC and palatovaginal canal, the horizontal, vertical and direct distances between VC and FR and the patterns of sphenoid sinus (SS) pneumatization. Results: The VC-pICA angle was more obtuse and VC and FR were placed farther off the midline on the left as compared to the right side. Similarly, the distances between VC and FR were more on the left side. The VC length and distance of VC and FR from the midline were longer in males than in females. The VC-pICA angle was more obtuse in females. The post-sellar variant was the predominant pneumatization pattern seen (57.9%), and the incidence of lateral recess pneumatization was 15%. Conclusion: The results of our study can be utilized for a better understanding of the anatomy of the skull base. In skull base pathologies with distorted anatomical landmarks, a basic understanding of their interrelations can be used to have a better anatomical orientation. All these measures can help in avoiding complications and make extended endoscopic approaches safe.

Posterior pedicle inferior turbinate flap for recurrent cerebrospinal fluid leak following endoscopic transsphenoidal surgery.

BACKGROUND: Adequate reconstruction of skull base following endoscopic transsphenoidal surgery is the most crucial step in reducing postoperative morbidity and mortality. Although, the success rate of traditional nasoseptal flap is very high, specific surgical scenarios preclude its use. A variety of vascularised endonasal and tunnelled scalp flaps have been described in the literature to address such situations. Posterior pedicle inferior turbinate flap (PPITF) is one such locally available vascularised flap. METHODS: Two patients with recurrent CSF leak following endoscopic transsphenoidal resection of pituitary adenoma were included. The nasoseptal flap was not available in both patients due to previous surgery. Hence, a PPITF based on the posterolateral nasal artery, a branch of sphenopalatine artery, was harvested and used for skull base reconstruction. RESULTS: In both patients, CSF leak subsided in the immediate postoperative period. In one patient, sensorium improved and was subsequently discharged in stable condition. Other patient succumbed to meningitis in the postoperative period. CONCLUSIONS: The PPITF is a valuable alternative to the conventional nasoseptal flap when the latter is not available and it is very important for an endoscopic skull base surgeon to be familiar with the technique of harvesting and using the PPITF.

Tadpole Sign in Filum Terminale Paragangliomas.

Two normotensive male patients came with complaints of low back pain. Contrast-enhanced magnetic resonance imaging of the lumbosacral spine revealed an enhancing intradural extramedullary lesion (at the L4-L5 vertebral level in the first patient and at the L2-L3 vertebral level in the second patient). The tumor resembled the head and caudal blood vessels the tail of a tadpole, thereby giving the "tadpole sign." This sign is an important radiologic and histopathologic correlate, which is helpful in preoperative diagnosis of spinal paraganglioma.

Morphometric Analysis of C2 Pedicle in 247 Patients and Proposal for Trajectory and Size of Pedicle Screw.

BACKGROUND: Screw diameters are currently available based on the literature available for the Western population. No data are available in such a large number of patients for the Indian population. OBJECTIVE: The aim of this study was to define the average pedicle size available and to determine the angulation for placement of screws for C2 pedicle in the Indian population. We also try to determine the pedicle screw diameter which can be used universally in most Indian patients, considering the pedicle dimensions. MATERIAL AND METHODS: Retrospective morphometric analysis of CT scans of 247 patients (152 M, 95 F) was done to calculate the C2 pedicle width (PW), pedicle height (PH), pedicle length (PL), pedicle transverse angle (PTA) and the craniocaudal angulation (CCA) of the C2 pedicle. RESULTS: Mean PW in females was 5.3 mm and in males it was 5.9 mm. This difference was statistically significant. The mean PH in the study population was 8.9 mm, while the mean PL was 29.7 mm. The mean PTA was 40.0 degrees and the CCA was 28.4 degrees. CONCLUSION: This is a morphometric analysis of the C2 pedicle which provides information for the surgeons to determine the safe site of entry and trajectory for the screw implantation. We conclude that a screw diameter of 2.7 mm can be safely implanted in a vast majority of the patient population.

Video Section-Operative Nuances: Step by Step - Donning and Doffing in Neurosurgical Operating Room.

BACKGROUND AND INTRODUCTION: Donning and doffing of personal protective equipments (PPE) has become relevant especially during COVID-19 pandemic and neurosurgeons operating upon COVID-19 positive or suspect patients should be aware of proper technique of donning and doffing of PPE.[1] Surgeries involving direct exposure of anterior nasal spaces/paranasal sinuses carry significantly more risk of infection and it may be prudent to use PPE while operating all such cases.[2]. OBJECTIVE: In this video, we present our extensive protocol of donning and doffing of PPE which we have devised for our operating room. TECHNIQUE: Donning consists of wearing of the PPE in a proper sequence so as to afford maximal protection from viral infection while conducting the surgical procedure. Various components of PPE and procedure of donning is shown followed by doffing, the sequential and safe removal of the PPE. RESULTS: A meticulous method of donning and doffing PPE for neurosurgeons handling COVID-19 positive / suspect cases has been shown . CONCLUSION: Proper sequence of donning and doffing of PPE gear is of crucial importance during the COVID pandemic to prevent infection to the health care workers while handling COVID-19 positive/suspect cases and this video demonstrates the protocol we use at our institute.

Supratentorial Neurenteric Cyst: A Rare Differential for a Frontal Cyst.

Supratentorial neurenteric cyst is a rare entity. They are usually isointense to slightly hyperintense on T1W images and hyperintense on T2-weighted/fluid attenuated inversion recovery images. There was a diagnostic dilemma in this case due to the cerebrospinal fluid intensity of the cyst on magnetic resonance imaging. Postoperative residual lesion predisposes to hemorrhage and seizures.

Cerebrospinal Fluid Leak in Juvenile Nasopharyngeal Angiofibroma-Rare Sequelae of Flutamide-Induced Tumor Shrinkage.

BACKGROUND: Nonsteroidal androgen receptor blockers like flutamide have been described as an adjuvant treatment for preoperative shrinkage of extensive juvenile nasopharyngeal angiofibroma. We present a case of cerebrospinal fluid (CSF) leak due to flutamide-induced tumor shrinkage. CASE REPORT: A 15-year-old male with a prior diagnosis of juvenile nasopharyngeal angiofibroma stage IIIB on preoperative flutamide for 3.5 weeks presented with altered sensorium, meningeal signs, and clear watery nasal discharge consistent with CSF leak. Computed tomogram of the head revealed air in the ventricle and repeat contrast-enhanced magnetic resonance imaging showed significant tumor shrinkage in the area of the anterior skull base. This patient had an atypical pattern of tumor extension into the anterior skull base through the roof of posterior ethmoid and sphenoid sinus, which are inherently weak areas of the skull base, thereby predisposing the CSF leak on tumor shrinkage. CONCLUSION: CSF leak is a rare complication following flutamide therapy, especially if large areas of the anterior skull base are involved.