Surgical corridors to foramen magnum meningiomas: a mini-review

Gross-total resection of foramen magnum meningiomas remains the gold standard of treatment and should be performed whenever possible. The transcondylar approach (and its variations) represents the most used approach for meningiomas located in the lateral or anterior borders of the foramen magnum. Endoscopic transclivus approaches represent a useful option in selected cases of anterior midline foramen magnum meningiomas, to be performed in centers with advanced experience in endoscopic skull base surgery, with the caveats of increased risk of postoperative cerebrospinal fluid leak. Alternatively, radiosurgery remains an option for well-selected cases, especially for the management of asymptomatic patients with small enlarging tumors. Advances in molecular profiling, as well as genetic analysis, may guide adjuvant treatment.

Endoscopy-assisted high anterior cervical approach in craniovertebral junction (CVJ)

BACKGROUND

Surgical procedures in the craniovertebral junction (CVJ) suffer from specific challenges due to the proximity between the cranium and spine containing the critical neurovascular structures and the brainstem, respectively. Owing to the complex transitional zone, it is highly challenging for classic surgical approaches to practically acquire the additional exposure to neurovascular structures of the CVJ. Inspired by these facts, we explore the feasibility of an endoscopy-assisted high anterior cervical approach in the CVJ.

METHODS

To explore the feasibility of an endoscopy-assisted approach, we quantitatively assessed the surgical corridor and extent of exposure of the CVJ in 6 cadaveric specimens using 0° and 30° endoscopes.

RESULTS

The applied endoscopes provided adequate exposure to neurovascular structures and the brainstem in the CVJ. Notably, the resection of the anterior arch of C1 is avoided in minimal anterior clivectomy. Further, improved exposure of the CVJ is obtained after removing the odontoid.

CONCLUSION

An endoscope-assisted high anterior cervical approach in the CVJ significantly preserved the cervical spine stability while minimalizing the risk of neurovascular injury within the surgical corridor.

Surgical anatomy and technical nuances of the endoscopic endonasal approach to the anterior cranial fossa

Endoscopic endonasal approaches (EEA) to the skull base have significantly impacted the management of lesions located in the cranial base. Specifically, lesions arising from the anterior cranial fossa, such as pituitary macroadenomas, craniopharyngiomas meningiomas and craniofacial malignancies have benefited from the development of such approaches. Understanding of the anatomy of the anterior fossa is of utmost importance for the successful selection of the approach and application of surgical techniques in EEA. In the current manuscript, we review the most relevant points of surgical anatomy and nuances of the surgical technique of EEA to the anterior fossa. Anatomical landmarks for the transtuberculum transplanum and transcribriform approaches are discussed and a step-by-step description for those approaches is presented. We reinforce that safe and effective application of such techniques follow the same principles of other skull base surgery techniques: mastering of surgical anatomy, adequate case selection, correct instrumentation and surgical experience.

Endoscopic Endonasal and Transcranial Surgery for Microsurgical Resection of Ventral Foramen Magnum Meningiomas: A Preliminary Experience

BACKGROUND

Purely ventral foramen magnum meningiomas are challenging tumors to treat given their location, and proximity and relationship to vital neurovascular structures.

OBJECTIVE

To present endoscopic endonasal surgery (EES) as a complementary approach to the far-lateral suboccipital approach (FLA) for ventral midline tumors.

METHODS

From May 2008 to October 2013, 5 patients underwent EES and 5 FLA for primary ventral foramen magnum meningiomas. We retrospectively reviewed their records to evaluate outcomes.

RESULTS

Nine of 10 patients presented with long-tract and lower cranial nerve deficits. All patients who presented with deficits preoperatively completely normalized after tumor resection regardless of approach. Gross total resection was achieved in 2 cases in the EES group and 4 cases in the FLA group (the rest were near total). Vascular encasement was a limitation to gross total resection with both approaches. Preoperative median Karnofsky Performance Scale score was 80 and improved to 100 in both groups. Following EES, 1 patient developed cerebrospinal fluid leak with resultant meningitis. Two patients developed hydrocephalus, one of which developed an epidural abscess following necrosis of the nasoseptal flap, requiring debridement. In the FLA group, 1 patient developed a pseudomeningocele associated with hydrocephalus. One patient developed an abdominal fat graft site hematoma.

CONCLUSION

Both approaches provide excellent results for resection of ventral foramen magnum meningiomas, with reconstruction and hydrocephalus as the main sources of complication. In our practice, EES is a preferred technique in ventral, purely midline tumors with limited inferior extension and reduced lower cranial nerve manipulation, whereas FLA is preferred in tumors with lateral and caudal extension below the tip of the dens.

Nasopharyngeal muscle patch for the management of internal carotid artery injury in endoscopic endonasal surgery

OBJECTIVE

Injury to the internal carotid artery (ICA) is the most critical complication of endoscopic endonasal skull base surgery. Packing with a crushed muscle graft at the injury site has been an effective management technique to control bleeding without ICA sacrifice. Obtaining the muscle graft has typically required access to another surgical site, however. To address this concern, the authors investigated the application of an endonasally harvested longus capitis muscle patch for the management of ICA injury.

METHODS

One colored silicone-injected anatomical specimen was dissected to replicate the surgical access to the nasopharynx and the stepwise dissection of the longus capitis muscle in the nasopharynx. Two representative cases were selected to illustrate the application of the longus capitis muscle patch and the relevance of clinical considerations.

RESULTS

A suitable muscle graft from the longus capitis muscle could be easily and quickly harvested during endoscopic endonasal skull base surgery. In the illustrative cases, the longus capitis muscle patch was successfully used for secondary prevention of pseudoaneurysm formation following primary bleeding control on the site of ICA injury.

CONCLUSIONS

Nasopharyngeal harvest of a longus capitis muscle graft is a safe and practical method to manage ICA injury during endoscopic endonasal surgery.

How I do it: endoscopic endonasal approach to the inferior third of the clivus

BACKGROUND

Nowadays, endoscopic endonasal expanded approach targeting for the clival lower third is well described in literature. Nonetheless, great variations can be found among surgical groups, specially during the earlier stages of this procedure.

METHOD

We present a step by step description of the clival lower third approach until entering the dural space, setting its bony limits. We describe the basipharyngeal flap tailoring as a helpful option for latter reconstruction. The study of cadaveric specimens adds clarifying dissections.

CONCLUSIONS

The expansion in the coronal plane is providential in most of the intradural lesions of the inferior clivus. Basipharyngeal flap may help seal the surgical defects in this area.

Innovation in neurosurgery: less than IDEAL? A systematic review

BACKGROUND

Surgical innovation is different from the introduction of novel pharmaceuticals. To help address this, in 2009 the IDEAL Collaboration (Idea, Development, Exploration, Assessment, Long-term follow-up) introduced the five-stage framework for surgical innovation. To evaluate the framework feasibility for novel neurosurgical procedure introduction, two innovative surgical procedures were examined: the endoscopic endonasal approach for skull base meningiomas (EEMS) and the WovenEndobridge (WEB device) for endovascular treatment of intracranial aneurysms.

METHODS

The published literature on EEMS and WEB devices was systematically reviewed. Identified studies were classified according to the IDEAL framework stage. Next, studies were evaluated for possible categorization according to the IDEAL framework.

RESULTS

Five hundred seventy-six papers describing EEMS were identified of which 26 papers were included. No prospective studies were identified, and no studies reported on ethical approval or patient informed consent for the innovative procedure. Therefore, no clinical studies could be categorized according to the IDEAL Framework. For WEB devices, 6229 articles were screened of which 21 were included. In contrast to EEMS, two studies were categorized as 2a and two as 2b.

CONCLUSION

The results of this systematic review demonstrate that both EEMS and WEB devices were not introduced according to the (later developed in the case of EEMS) IDEAL framework. Elements of the framework such as informed consent, ethical approval, and rigorous outcomes reporting are important and could serve to improve the quality of neurosurgical research. Alternative study designs and the use of big data could be useful modifications of the IDEAL framework for innovation in neurosurgery.

Impact of timing of radiotherapy in patients with newly diagnosed glioblastoma

OBJECTIVE

To further evaluate if a delay in the start of radiation therapy (RT) affects patient outcomes for glioblastoma (GBM).

PATIENTS AND METHODS

From May 1999 to May 2010, a total of 161 patients underwent surgery followed by RT for GBM. We assessed overall survival (OS) and progression free survival (PFS), stratified by extent of surgical resection. Included in the analysis were genomic predictors of progression.

RESULTS

Median time from surgery to start of RT was 20days for biopsy alone, 28days for subtotal resection (STR) and 28days for gross total resection (GTR). For all patients, a delay >28days did not result in a difference in PFS when compared to no delay (6.7 vs. 6.9 months, p=0.07). PFS was improved in biopsy or STR patients with a >28day delay to start of RT (4.2 vs. 6.7 months, p=0.006). OS was also improved in patients receiving biopsy or STR with a >28day delay to start of RT (12.3 vs. 7.8 months, p=0.005). Multivariable analysis (MVA) demonstrated an improvement in OS and PFS with time to RT >28days for biopsy or STR patients (HR 0.52 p=0.008 and HR 0.48 p=0.02, respectively).

CONCLUSION

In this retrospective review of GBM patients treated at a single institution, OS and PFS were not different between time to RT >28days compared to <28 days. There was a modest improvement in both PFS and OS in patients who received biopsy or STR with time to RT >28 days.

The use of a three-dimensional endoscope for different skull base tumors: results of a preliminary extended endonasal surgical series

BACKGROUND

The evolution of skull base surgery over the past decade has been influenced by advancement in visualization technology. Recently, as a result of such improvements, three-dimensional (3-D) scopes have been widely used during endoscopic endonasal approaches. In the present study, we describe the use of 3-D stereoscopic endoscope for the treatment of a variety of skull base lesions.

METHODS

From January 2010 to June 2015, a 3-D endoscopic endonasal approach (4 and 4.9 mm, 0°, and 30° rigid endoscopes) was performed in 70 patients with the following lesions: 42 large extrasellar pituitary macroadenomas, seven tuberculum sellae meningiomas, seven clivus chordomas, five craniopharyngiomas, three fibrous dysplasia of the clivus, three sinonasal malignancies, one orbital lymphangioma, one trigeminal neurinoma, one primary suprasellar lymphoma.

RESULTS

Total tumor removal was obtained in 50 patients (71.4 %) while in 14 (20 %), subtotal removal was possible in six (8.6 %) only partial removal was achieved. Overall complications included diabetes insipidus in eight patients (11.4 %), hypopituitarism in seven patients (10 %), CSF leak in five patients (7.1 %), cranial nerve injury in two patients (2.8 %), panhypopituitarism in two patients (2.8 %), meningitis in one (1.4 %) and one postoperative central retinal artery occlusion (1.4 %). There was no mortality in the series. The mean follow-up time was 39 months (range, 6-72 months).

CONCLUSIONS

In our experience, the 3-D endoscope represents a critical development in visualization, thus enabling improved hand-eye coordination and depth perception, which are mandatory for the management of complex intradural neurovascular structures during tumor removal surgery.