[Neurophysiologic intraoperative monitoring to preserve cranial nerve function in base of skull surgery]

Endoscopic endonasal surgery for epidermoid and dermoid cysts: a 10-year experience

OBJECTIVE

Epidermoid and dermoid cysts may be found along the cranial base and are commonly resected via open transcranial approaches. The use of endoscopic endonasal approaches for resection of these tumors has been rarely reported.

METHODS

The authors retrospectively reviewed the medical records of 21 patients who underwent endoscopic endonasal surgery for epidermoid and dermoid cyst resection at the University of Pittsburgh Medical Center between January 2005 and June 2014. Surgical outcomes and variables that might affect the extent of resection and complications were analyzed.

RESULTS

Total resection (total removal of cyst contents and capsule) was achieved in 8 patients (38.1%), near-total resection (total removal of cyst contents, incomplete removal of cyst capsule) in 9 patients (42.9%), and subtotal resection (incomplete removal of cyst contents and capsule) in 4 patients (19%). Larger cyst volume (≥ 3 cm3) and intradural location (15 cysts) were significantly associated with nontotal resection (p = 0.008 and 0.0005, respectively). In the whole series, surgical complications were seen in 6 patients (28.6%). No complications were observed in patients with extradural cysts. Among the 15 patients with intradural cysts, the most common surgical complication was postoperative CSF leak (5 patients, 33.3%), followed by postoperative intracranial infection (4 patients, 26.7%). Larger cysts and postoperative CSF leak were associated with intracranial infection (p = 0.012 and 0.028, respectively). Subtotal resection was marginally associated with intracranial infection when compared with total resection (p = 0.091). All patients with neurological symptoms improved postoperatively with the exception of 1 patient with unchanged abducens nerve palsy.

CONCLUSIONS

Endoscopic endonasal approaches may be effectively used for resection of epidermoid and dermoid cysts in carefully selected cases. These approaches are recommended for cases in which a total or near-total resection is possible in addition to a multilayer cranial base reconstruction with vascularized tissue to minimize the risk of intracranial infection.

Intra-operative monitoring of the spinal accessory nerve: a systematic review

Objective:

To investigate evidence that intra-operative nerve monitoring of the spinal accessory nerve affects the prevalence of post-operative shoulder morbidity and predicts functional outcome.

Methods:

A search of the Medline, Scopus and Cochrane databases from 1995 to October 2012 was undertaken, using the search terms ‘monitoring, intra-operative’ and ‘accessory nerve’. Articles were included if they pertained to intra-operative accessory nerve monitoring undertaken during neck dissection surgery and included a functional shoulder outcome measure. Further relevant articles were obtained by screening the reference lists of retrieved articles.

Results:

Only three articles met the inclusion criteria of the review. Two of these included studies suggesting that intra-operative nerve monitoring shows greater specificity than sensitivity in predicting post-operative shoulder dysfunction. Only one study, with a small sample size, assessed intra-operative nerve monitoring in neck dissection patients.

Conclusion:

It is unclear whether intra-operative nerve monitoring is a useful tool for reducing the prevalence of accessory nerve injury and predicting post-operative functional shoulder outcome in patients undergoing neck dissection. Larger, randomised studies are required to determine whether such monitoring is a valuable surgical adjunct.

[Modern skull base surgery from the perspective of neurosurgeons]

At present, modern skull base surgery is a highly sophisticated interdisciplinary collaboration of various diagnostic and therapeutic disciplines. The overall goal is the treatment of complex tumorous, traumatic, vascular and inflammatory processes or developmental disorders of the skull base with preservation of function. The paper presents modern concepts, procedures and minimally invasive strategies in skull base surgery and also critically discusses the current trend to endoscopic and robot-assisted surgical techniques.

[Sonography aided computer assisted surgery (SACAS) in orbital surgery]

BACKGROUND

The application of computer assisted procedures in orbital surgery is made more difficult by the intraoperative tissue shift in intraorbital structures, since this intraoperative dislocation cannot be imaged in preoperative CT/MR datasets.

METHODS

After preoperative recording of CT and/or MR datasets in five patients with orbita affected by frontobasal tumors, we used intraoperative sonography by coupling the ultrasound unit to the navigation system.

RESULTS

Registration, referencing and calibration of the ultrasound system proceeded without any difficulties. Intraoperatively, the structures of the anterior and middle thirds of the orbita and their tissue shift could be particularly well evaluated sonographically.

CONCLUSION

The use of navigated sonography enables repeated intraoperative re-evaluation of preoperative CT/MR datasets. The fusion of intraoperative sonography with preoperative imaging visualizes the tissue shift and facilitates the identification of anatomical structures and the spatial orientation of the surgeon. This appears to allow both increased operative radicality and greater tissue protection. In our opinion, the intraoperative parallel application of a non-calibrated ultrasound system and an only CT/MRT based navigation system cannot fulfill these requirements because of anatomical complexity.