Facial and lower cranial nerve function preservation in lateral approach for craniocervical schwannomas

Retrolabyrinthine transsigmoid approach to complex parabrainstem tumors in the posterior fossa

OBJECTIVE

The surgical management of large and complex tumors of the posterior fossa poses a formidable challenge in neurosurgery. The standard retrosigmoid craniotomy approach has been performed at most neurosurgical centers; however, the retrosigmoid approach may not provide enough working space without significant retraction of the cerebellum. The transsigmoid approach provides wider and shallower surgical fields; however, there have been few clinical and no cadaveric studies on its usefulness. In the present study, the authors describe the transsigmoid approach in clinical cases and cadaveric specimens.

METHODS

For the clinical study, the authors retrospectively reviewed the medical records and operative charts of patients who had been surgically treated for parabrainstem tumors using the transsigmoid approach between 1997 and 2019. They analyzed patient demographic and clinical data, as well as surgical and clinical outcomes. In the cadaveric study, they compared the surgical views obtained in different approaches (retrosigmoid, presigmoid, retrolabyrinthine, and transsigmoid) and measured the sigmoid sinus width at the level of the endolymphatic sac and the distance between the anterior edge of the sigmoid sinus and the endolymphatic sac on 35 sides in 19 cadaveric specimens.

RESULTS

A total of 21 patients (6 males and 15 females) with a mean age of 42.2 (range 15-67) years were included in the clinical study. Eleven patients had meningioma, 7 had vestibular schwannoma, 2 had hemangioblastoma, and 1 had epidermoid cyst. Gross-total, near-total, and subtotal removal were achieved in 7 (33.3%), 3 (14.3%), and 11 (52.4%) patients, respectively. In the cadaveric study, 19 cadaveric specimens were used. The sigmoid sinus was cut in the middle, and the incision was extended from the retrosigmoid to the presigmoid dura. The dura was then retracted upward and downward like opening a door. The results indicated that this technique can widen the operative field anteriorly by approximately 2 cm as compared to the retrosigmoid approach and provides a better view anterior to the brainstem.

CONCLUSIONS

The transsigmoid approach is useful for complex parabrainstem tumors in the posterior fossa because it provides a wider and shallower operative view with less retraction of the cerebellum. This enables safer tumor removal with less damage to important structures in the posterior fossa, resulting in better operative and clinical outcomes.

Facial reanimation with interposition nerve graft or masseter nerve transfer: a comparative retrospective study

Both interposition nerve grafts and masseter nerve transfers have been successfully used for facial reanimation after irreversible injuries to the cranial portion of the facial nerve. However, no comparative study of these two procedures has yet been reported. In this two-site, two-arm, retrospective case review study, 32 patients were included. Of these, 17 patients (eight men and nine women, mean age 42.1 years) underwent interposition nerve graft after tumor extirpation or trauma between 2003 and 2006 in the Ear Institute, School of Medicine, Shanghai Jiao Tong University, China, and 15 patients (six men and nine women, mean age 40.6 years) underwent masseter-to-facial nerve transfer after tumor extirpation or trauma between November 2010 and February 2016 in Shanghai Ninth People's Hospital, China. More patients achieved House-Brackmann III recovery after masseter nerve repair than interposition nerve graft repair (15/15 vs. 12/17). The mean oral commissure excursion ratio was also higher in patients who underwent masseter nerve transfer than in patients subjected to an interposition nerve graft. These findings suggest that masseter nerve transfer results in strong oral commissure excursion, avoiding obvious synkinesis, while an interposition nerve graft provides better resting symmetry. This study was approved by the Institutional Ethics Committee, Shanghai Ninth People's Hospital, China (approval No. SH9H-2019-T332-1) on December 12, 2019.

Prognostic factors affecting the surgical outcome of anterolateral benign tumors in the foramen magnum region

INTRODUCTION

Anterior and anterolateral tumors in foramen magnum region are rare and surgically challenging although most of them are benign. The optimal approach is debatable and prognostic factors affecting surgical outcome remains unclear. We aimed to identify factors including surgical approach determining postoperative outcome.

METHODS

The data of 49 patients diagnosed benign tumors involving the anterior and anterolateral foramen magnum were retrospectively analyzed in our institution from January 2009 to January 2015. The demographic, clinicoradiological, surgical and follow-up information were collected. Primary surgical outcome was new neurological deficits. A multivariate analysis was performed to determine predictors of postoperative neurological deficits.

RESULTS

Patients were operated on either via suboccipital (31 cases, 63.3%) or far lateral (18 cases, 36.7%) approach. Newly developed neurological deficits occurred in 11 (22.4%) patients, improved over time in 6 (12.2%) patients. 2 (4.1%) patients died within 3 month after operation and 2 (4.1%) suffered tumor recurrence. 44 (93.6%) out of 47 survivors had good functional outcome (postoperative Karnofsky performance score ≥80) at last follow-up period. Patients with postoperative new neurodeficits harbored tumors which tended to more frequently involve lower third clivus (p = 0.083), to be meningiomas (p = 0.059), were more likely to be removed through far lateral approach (p = 0.010) and have extradural extension (p = 0.024). Multivariate analysis showed that the far lateral approach was the sole predictor independently related to postoperative neurological deficits (p = 0.029).

CONCLUSIONS

The far lateral approach to benign tumors anterolateral to foramen magnum experienced higher rate of immediate new neurological deficits compared to suboccipital approach. The role of the suboccipital approach may be underestimated and should be further evaluated.