Faculty Bibliography

OBJECTIVES/HYPOTHESIS: The development of expanded endoscopic endonasal approaches (EEAs) has allowed resection of cranial-base lesions beyond the sella. One major criticism is an increased risk of postoperative cerebrospinal fluid (CSF) leakage because of the larger skull base defect. We evaluated our experience with vascularized pedicled nasoseptal flap (PNSF) reconstruction and compared the postoperative CSF leak rates between patients undergoing endoscopic transsphenoidal (transsellar) approaches versus expanded EEA (transplanum-transtuberculum, transcribriform, transclival). STUDY DESIGN: Retrospective analysis at a tertiary care medical center. METHODS: A retrospective review of a prospective database was performed on patients who underwent PNSF reconstruction for intraoperative high-flow CSF leaks after EEA between December 2008 and August 2011. Demographic data, repair materials, surgical approach, and incidence of postoperative CSF leaks were collected. RESULTS: Thirty-seven transsellar defects (group I) were repaired with a PNSF, and 32 expanded EEA defects (19 transplanum-transtuberculum, 10 transcribriform, three transclival) (group II) were repaired with a PNSF. No postoperative CSF leaks occurred in group I. One delayed postoperative CSF leak was encountered in group II leading to a 3.1% leak rate in that group. The incidence of postoperative CSF leakage was not significantly different between the two groups (P > .05). Our overall success rate in this series using a PNSF was 98.6%. CONCLUSIONS: Based on our data, there is no significant increased risk of postoperative CSF leak between transsellar and expanded EEA defects when a PNSF is used. The potential risk of postoperative CSF leaks associated with larger defects created through expanded EEA can be minimized by multilayered closure with a PNSF and meticulous surgical technique.

Lateral sphenoid encephaloceles of the Sternberg canal are rare entities and usually present with spontaneous CSF rhinorrhea. Traditionally, these were treated via transcranial approaches, which can be challenging given the deep location of these lesions. However, with advancements in endoscopic skull base surgery, including improved surgical exposures, angled endoscopes and instruments, and novel repair techniques, these encephaloceles can be resected and successfully repaired with purely endoscopic endonasal approaches. In this report, the authors review the endoscopic endonasal transpterygoid approach to the lateral recess of the sphenoid sinus for repair of temporal lobe encephaloceles, including an overview of the surgical anatomy from an endoscopic perspective, and describe the technical operative nuances and surgical pearls for these cases. The authors also present 4 new cases of lateral sphenoid recess encephaloceles that were successfully treated using this approach.

Extended endoscopic endonasal approaches have allowed for a minimally invasive solution for removal of a variety of ventral skull base lesions, including intradural tumors. Depending on the location of the pathological entity, various types of surgical corridors are used, such as transcribriform, transplanum transtuberculum, transsellar, transclival, and transodontoid approaches. Often, a large skull base dural defect with a high-flow CSF leak is created after endoscopic skull base surgery. Successful reconstruction of the cranial base defect is paramount to separate the intracranial contents from the paranasal sinus contents and to prevent postoperative CSF leakage. The vascularized pedicled nasoseptal flap (PNSF) has become the workhorse for cranial base reconstruction after endoscopic skull base surgery, dramatically reducing the rate of postoperative CSF leakage since its implementation. In this report, the authors review the surgical technique and describe the operative nuances and lessons learned for successful multilayered PNSF reconstruction of cranial base defects with high-flow CSF leaks created after endoscopic skull base surgery. The authors specifically highlight important surgical pearls that are critical for successful PNSF reconstruction, including target-specific flap design and harvesting, pedicle preservation, preparation of bony defect and graft site to optimize flap adherence, multilayered closure technique, maximization of the reach of the flap, final flap positioning, and proper bolstering and buttressing of the PNSF to prevent flap dehiscence. Using this technique in 93 patients, the authors' overall postoperative CSF leak rate was 3.2%. An illustrative intraoperative video demonstrating the reconstruction technique is also presented.

Bone morphogenetic protein (BMP) has been reported to cause early inflammatory changes, ectopic bony formation, adjacent level fusion, radiculitis, and osteolysis. The authors describe the case of a patient who developed inflammatory fibroblastic cyst formation around the BMP sponge after a lumbar fusion, resulting in compressive lumbar radiculopathy. A 70-year-old woman presented with left L-4 and L-5 radiculopathy caused by a Grade I spondylolisthesis with a left herniated disc at L4-5. She underwent a minimally invasive transforaminal lumbar interbody fusion with BMP packed into the interbody cage at L4-5. Her neurological symptoms resolved immediately postoperatively. Six weeks later, the patient developed recurrence of radiculopathy. Radiological imaging demonstrated an intraspinal cyst with a fluid-fluid level causing compression of the left L-4 and L-5 nerve roots. Reexpoloration of the fusion was performed, and a cyst arising from the posterior aspect of the cage was found to compress the axilla of the left L-4 nerve root and the shoulder of the L-5 nerve root. The cyst was decompressed, and the wall was partially excised. A collagen BMP sponge was found within the cyst and was removed. Postoperatively, the patient's radiculopathy resolved and she went on to achieve interbody fusion. Bone morphogenetic protein can be associated with inflammatory cyst formation resulting in neural compression. Spine surgeons should be aware of this complication in addition to the other reported BMP-related complications.

The pineal gland has been studied through philosophy and science for thousands of years. Its role in human physiology was not well understood until the scientific community first started to report on pineal pathology in the eighteenth century. Throughout the nineteenth and twentieth centuries, reports on pineal tumors and the emergence of comparative anatomy allowed more complete understanding of pineal function. Neurosurgical methods of treating pineal pathology first emerged in the early twentieth century. In the latter half of the twentieth century, the emergence of microsurgical technique allowed for excellent outcomes with minimal morbidity and mortality.