gms | German Medical Science

Objective: To perform a risk assessment of endoscope-assisted microsurgery via transcranial approaches for posterior fossa lesions.

Methods: We evaluated 85 patients who underwent endoscope-assisted surgery for various pathologies of the posterior fossa via transcranial approaches in our department from February 2010 to March 2015. Retrospectively we analyzed the patients charts, surgical reports, pre- and postoperative neuroradiological data, intraoperative video recordings, ICU charts and follow-up data. We focused in particular on morbidity and mortality due to the endoscopic procedure. All surgeries were performed combining microscope (Pentero OPMI, Karl Zeiss, Oberkochen) and the rigid endoscope (0°, 30°, 45° optics, Karl Storz, Tuttlingen). The angled optics were always introduced under direct microscopic control.

Results: The mean age of patients was 47.24 ± 13,99 years; 37 were male and 48 were female. The pathologies treated were: Vestibular schwannomas (40), Epidermoid cysts (17), Posterior circulation aneurysms (6), one Chordoma (1), one Chondrosarcoma (1), Meningiomas (3), Trigeminal neuralgias (6), one Trigeminal ganglion inflammation (1), one Trigeminal neurinoma (1), Fourth ventricle ependymomas (3), one Brainstem cavernoma (1), one Vagus neurinoma (1), one Brain stem glioma (1), one CSF Fistula (1), Foramen magnum lesions (2), one Hemifacial spasm (1). The lesions were managed by following approaches: lateral suboccipital (72 cases), median suboccipital (8 cases), pterional (3 cases), far lateral (1 case), subtemporal (1 case). New neurological deficits immediately after surgery appeared in 22 cases and included 1 case of dysphagia, 1 case of abducens paralysis, 1 case of trochlear paralysis, 19 cases of facial palsy. All deficits were temporary and recovered in the follow-up besides the trochlear lesion and one case of facial palsy which needed a sural graft. Further, occurred 2 cases of postoperative infection, 4 cases of CSF fistula, 1 case of vascular insult (PICA insult). The mortality rate was 0%. Regarding the use of the endoscope, no thermal CN injury occurred. In one case the trochlear nerve was injured mechanically due to the endoscope.

Conclusion: The endoscope helps to explore hidden areas of posterior fossa minimizing drilling and retraction of neurovascular and brain structures. Using the endoscope in addition to the microscope enables a safer surgery in posterior fossa even for lesions which aren´t visible in a straight line by microscopic view. The risks due to insertion of the endoscope under microscopic guidance are minimal. We expect that new advancement in the endoscopic instrument will enable more improvement in the endoscopic-assisted surgery.