Endoscopic and Gravity-Assisted Resection of Medial Temporo-occipital Lesions Through a Supracerebellar Transtentorial Approach: Technical Notes With Case Illustrations

BACKGROUND

Traditional approaches to medial temporo-occipital intra-axial brain tumors carry the risk of visual or language deficits related to brain retraction or transgression of deep fiber tracts. To reduce these risks, the microscopic supracerebellar transtentorial approach with the patient in the sitting position has been previously described for lesions in relative proximity to the tentorium.

OBJECTIVE

We describe this approach performed with endoscopic tumor resection to allow better visualization and a more ergonomic operating position.

METHODS

Four consecutive patients harboring a medial temporo-occipital lesion are reported. All were operated on while in the sitting position using frameless navigation and a supracerebellar transtentorial approach. Tumor resection was performed by 2 surgeons with endoscopic visualization.

RESULTS

Pathologies included intraparenchymal metastatic melanoma, cavernous hemangioma, and ganglioglioma, as well as an intraventricular metastatic tumor. The distance from the tentorium to the lesion ranged from 1 to 4 mm. Gross total resection was achieved in 3 of the 4 patients. The patient with a metastatic melanoma had an intentional near-total resection given the tumor encasing a branch of the posterior cerebral artery. The patient with the intraventricular tumor sustained a small but symptomatic infarct of the lateral geniculate region, resulting in a visual field deficit.

CONCLUSION

This small series suggests that the endoscopic supracerebellar transtentorial approach with the patient in the sitting position can be a safe and effective approach for removing medial temporo-occipital lesions. It allows excellent tumor visualization, eliminates the need for brain retraction, minimizes parenchymal transgression, and improves surgical ergonomics. Significant experience in endoscopy and excellent neuroanesthesia support are recommended before undertaking this approach.

Impact of selective pituitary gland incision or resection on hormonal function after adenoma or cyst resection

OBJECTIVE

With the resection of pituitary lesions, the anterior pituitary gland often obstructs transsphenoidal access to the lesion. In such cases, a gland incision and/or partial gland resection may be required to obtain adequate exposure. We investigate this technique and determine the associated risk of post-operative hypopituitarism.

METHODS

All patients who underwent surgical resection of a pituitary adenoma or Rathke cleft cyst (RCC) between July 2007 and January 2013 were analyzed for pre- and post-operative hormone function. The cohort of patients with gland incision/resection were compared to a case-matched control cohort of pituitary surgery patients. Total hypophysectomy patients were excluded from outcome analysis.

RESULTS

Of 372 operations over this period, an anterior pituitary gland incision or partial gland resection was performed in 79 cases (21.2 %). These include 53 gland incisions, 12 partial hemi-hypophysectomies and 14 resections of thinned/attenuated anterior gland. Diagnoses included 64 adenomas and 15 RCCs. New permanent hypopituitarism occurred in three patients (3.8 %), including permanent DI (3) and growth hormone deficiency (1). There was no significant difference in the rate of worsening gland dysfunction nor gain of function. Compared to a control cohort, there was a significantly lower incidence of transient DI (1.25 vs. 11.1 %, p = 0.009) but no significant difference in permanent DI (3.8 vs. 4.0 %) in the gland incision group.

CONCLUSION

Selective gland incisions and gland resections were performed in over 20 % of our cases. This technique appears to minimize traction on compressed normal pituitary gland during removal of large lesions and facilitates better visualization and removal of cysts, microadenomas and macroadenomas.

Avoidance of postoperative epistaxis and anosmia in endonasal endoscopic skull base surgery: a technical note

BACKGROUND

Most endoscopic transsphenoidal approaches jeopardize the sphenopalatine artery and septal olfactory strip (SOS), increasing the risk of postoperative anosmia and epistaxis while precluding the ability to raise pedicled nasoseptal flaps (NSF). We describe a bilateral "rescue flap" technique that preserves the mucosa containing the nasal-septal vascular pedicles and the SOS. This approach can reduce the risk of postoperative complications, including epistaxis and anosmia.

METHODS

A retrospective analysis was conducted of all patients who underwent endoscopic transsphenoidal surgery with preservation of both sphenopalatine vascular pedicles and SOS. In a recent subset of patients, olfactory assessment was performed.

RESULTS

Of 174 consecutive operations performed in 161 patients, bilateral preservation of the sphenopalatine vascular pedicle and SOS was achieved in 139 (80 %) operations, including 31 (22 %) with prior transsphenoidal surgery. Of the remaining 35 operations, 18 had a planned formal NSF and 17 had prior surgery or extensive lesions precluding use of this technique. Of pituitary adenomas, RCCs or sellar arachnoid cysts, 118 (94 %) underwent this approach, including 91 % of patients who had prior surgery. Preoperative olfaction function was maintained in 97 % of patients that were tested. None of the patients had postoperative arterial epistaxis.

CONCLUSION

Preservation of bilateral sphenopalatine vascular pedicles and the SOS is feasible in over 90 % of patients undergoing endonasal endoscopic surgery for pituitary adenomas and RCCs. This approach, while not hindering exposure or limiting instrument maneuverability, preserves the nasoseptal vasculature for future NSF use if needed and appears to minimize the risks of postoperative arterial epistaxis and anosmia.

Critical appraisal of extent of resection of clival lesions using the expanded endoscopic endonasal approach

Objectives To present a critical evaluation of our experience using an expanded endoscopic endonasal approach (EEEA) to clival lesions and evaluate, based on the location of residual tumor, what the anatomic limitations to the approach are. Design A retrospective review of all endoscopic endonasal operations performed at our institution identified 19 patients with lesions involving the clivus. Extent of resection was determined by preoperative and postoperative tumor volumes. Results Three patients underwent planned subtotal resections. Of the remaining patients, gross total resection was achieved in 8/16 (50%), > 95% in 5/16 (31%), and < 95% in 3/16 (19%). Residual tumor occurred, most commonly with extension posterior and lateral to the internal carotid artery, with inferior, lateral invasion of the occipital condyle and with deep inferior extension to the midportion of the dens. Conclusions The EEEA represents a safe and effective technique for the resection of clival lesions. Despite excellent overall visualization of this region we found that adequate exposure of the most lateral and inferior portions of large tumors is often difficult. Knowledge of these limitations allows us to determine which tumors are best suited for an EEEA and which may be more appropriate for an open skull base or combined technique.

Two-handed endoscopic-directed vestibular nerve sectioning: case series and review of the literature

OBJECT

Vestibular nerve sectioning is an accepted surgical treatment option for patients with medically refractory Ménière disease. In this paper the authors introduce and evaluate a 2-handed endoscopic-directed technique for vestibular nerve section.

METHODS

Eleven patients underwent a retrosigmoid craniectomy for endoscopic-directed vestibular nerve sectioning as treatment for intractable vertigo associated with Ménière disease. In all patients, identification and dissection of the cranial nerve VII/VIII complex was performed entirely under endoscopic guidance. The authors used the specially designed Frazee II neuroendoscope, consisting of a traditional endoscope lens with a microsuction attachment.

RESULTS

Vestibular nerve sectioning was completed in all 11 patients. Postoperative improvement in vertiginous episodes was achieved in 10 patients (91%). Auditory function was noted to be worse postoperatively in only 1 patient (9%). The same patient also developed a House-Brackmann Grade III facial nerve palsy, which improved gradually over time. There were no further complications, including no delayed CSF leaks.

CONCLUSIONS

The endoscopic-directed approach represents a safe and effective method for performing vestibular nerve sectioning. Until now, the endoscope has been used primarily as an adjunct to the operating microscope in surgery at the cerebellopontine angle. In addition, previous endoscopic techniques typically require a third hand to manipulate the endoscope. With the 2-handed endoscopic-directed technique, however, the endoscope is used as the primary means of visualization, and the unique design of this endoscope allows for a bimanual procedure without the requirement of a cosurgeon. Advantages of using this technique compared with the microscope include superior brightness at close distances, greater depth of field, increased maneuverability within small regions, and an improved ability to visualize objects not in a direct line of sight. Among other things, this allows for minimally invasive openings, decreased cerebellar retraction, and better identification of nerve cleavage planes and vascular anatomy.

Comparison of polyetheretherketone cages with femoral cortical bone allograft as a single-piece interbody spacer in transforaminal lumbar interbody fusion

OBJECT

Transforaminal lumbar interbody fusion (TLIF) is an accepted alternative to circumferential fusion of the lumbar spine in the treatment of degenerative disc disease, spondylolisthesis, and recurrent disc herniation. To maintain disc height while arthrodesis takes place, the technique requires the use of an interbody spacer. Although titanium cages are used in this capacity, the two most common spacers are polyetheretherketone (PEEK) cages and femoral cortical allografts (FCAs). The authors compared the clinical and radiographic outcomes of patients who underwent TLIF with pedicle screw fixation, in whom either a PEEK cage or an FCA was placed as an interbody spacer.

METHODS

The charts and x-ray films obtained in 39 patients (age range 33-68 years, mean 44.7 years) who underwent single-level TLIF between October 2001 and April 2004 and in whom either a PEEK cage (18 patients) or FCA (21 patients) was placed as an interbody spacer were evaluated in a retrospective study. Radiological outcome was based on fusion rate and a comparison of the initial postoperative lordotic angle on standing lateral radiographs with that at long-term follow up (mean follow up 15.1 months, minimum 12 months). To control for variations in radiographic magnification, the authors used lordotic angle as an indirect measure of disc space height. Clinical outcome was assessed using the Oswestry Disability Index (ODI). There were no major complications in either group. Radiographically documented fusion occurred in all patients in the PEEK group and 95.2% of those in the FCA group. Pseudarthrosis developed in one patient in the FCA group, and this patient underwent additional surgery. In both groups, the mean lordotic angle changed by less than 2.20 degrees during the postoperative period, and the mean postoperative ODI score was more than 40 points lower than the mean preoperative score. There was no significant difference between the two groups in mean change in lordotic angle (p = 0.415) and mean change in ODI score (p = 0.491).

CONCLUSIONS

Both PEEK cages and FCAs are highly effective in promoting interbody fusion, maintaining postoperative disc space height, and achieving desirable clinical outcomes in patients who undergo TLIF with pedicle screw fixation. The advantages of PEEK cages include a lower incidence of subsidence and their radiolucency, which permits easier visualization of bone growth.

Prenatal cocaine and/or nicotine exposure in rats: preliminary findings on long-term cognitive outcome and genital development at birth

Prenatal cocaine or nicotine exposure is associated with a variety of teratogenic effects. The current study was conducted to determine their effects alone and in combination on cognitive function and sexual differentiation. Pregnant Long-Evans rats (N = 19) were exposed to either cocaine (15 mg/kg/dose b.i.d. SC on GD 8-20); nicotine (4 mg/kg/day continuous SC infusion on GD 4-20); both nicotine + cocaine; or vehicle only. Birth weight and anogenital distance (AGD) were measured in all pups at birth. Learning and memory were tested in the Morris water maze (MWM) during prepubertal and pubertal ages in five daily consecutive sessions and a sixth session 1 week later and in the radial-arm maze (RAM) during adulthood. In the RAM, a drug challenge of the beta-noradrenergic antagonist propranolol (10-20 mg/kg) was given after acquisition training. Maternal weight gain was reduced 13-42% and offspring birth weight was reduced by 7-12% in all three exposure groups compared to controls. Cocaine decreased the AGD of males (2.68 mm) compared to 2.88 mm in noncocaine-exposed male pups (p < 0.025). A sex-selective cocaine effect was also seen after adjustment of AGD measurements for body weight. With this measure cocaine-treated females showed significantly (p < 0.05) greater AGD than those not exposed to cocaine. In the MWM, there were two types of trials: cued reference memory trials and uncued spatial working memory trials. On cued reference memory trials significant cocaine-induced latency deficits were seen on only the first session. On spatial working memory trials cocaine-induced latency deficits were seen throughout daily training on sessions 1-5, but not the retention session 6, 1 week later. During RAM acquisition, there were no significant differences in choice accuracy between exposure groups. Following propranolol challenge, deficits in choice accuracy were demonstrated in rats prenatally exposed to cocaine or nicotine. These rats did not show any response to propranolol, whereas the controls slightly improved their choice accuracy. The results of this study indicated that prenatal cocaine exposure altered long-term cognitive function under basal conditions in the MWM and drug challenge in the RAM, birth weight, and genital development. Cocaine-induced cognitive deficits were predominately in working memory rather than reference memory or long-term retention. Prenatal nicotine exposure was only observed to alter birth weight and cognitive function in response to propranolol challenge in the RAM.