Delayed Facial Nerve Palsy Following Resection of Vestibular Schwannoma: Clinical and Surgical Characteristics

Abstract

Objective: Analyze delayed facial nerve palsy (DFNP) following resection of vestibular schwannoma (VS) to describe distinct characteristics and facial nerve (FN) functional course. Study Design: Prospective cohort with retrospective review. Setting: Academic medical center. Patients: Consecutive patients undergoing VS resection 11/2017 to 08/2020. Exclusion criteria: preoperative House-Brackmann (HB) ! III, postoperative HB ! III without delayed palsy, <30 days follow-up. Interventions: VS resection with intraoperative electromyographic monitoring. Main Outcome Measures: FN outcomes utilizing the HB scale; comparison between patients with DFNP (deterioration greater than one HB grade 24 hours to 30 days postoperatively) vs. those with HBI-II throughout. Results: Two hundred eighty-eight patients met criteria: mean age 47.6 years, 36.1% male; 24.0% middle cranial fossa, 28.5% retrosigmoid, 47.6% translabyrinthine. DFNP occurred in 31 (10.8%) patients with average time to onset of 8.1 days. Of these, 22 (71.0%) recovered HBI-II and 3 (9.7%) recovered HBIII. Patients who experienced DFNP, on average, had larger maximum tumor diameter (23.4 vs. 18.7 mm, p ¼ 0.014), lower rate of gross-total resection (54.8% vs. 75.5%, p ¼ 0.014), and lower rate of !100 mV FN response to 0.05 mA stimulus intraoperatively (80.6% vs. 94.9%, p ¼ 0.002). Compared to overall incidence of DFNP, translabyrinthine approach demonstrated higher incidence (15.3%, p ¼ 0.017) while retrosigmoid lower (3.7%, p ¼ 0.014). In multivariable logistic regression, patients with FN response !100 mV to 0.05 mA stimulus were 72.0% less likely to develop DFNP ( p ¼ 0.021). Conclusions: Intraoperative electromyographic facial nerve response, tumor size, surgical approach, and extent of resection may play a role in development of DFNP following resection of VS. Most patients who develop DFNP recover near-normal function.

Delayed motor weakness following peripheral nerve schwannoma resection: illustrative cases

“… 9 Some studies have shown the translabyrinthine approach to have a higher incidence of DFP (15.3%) compared to the overall incidence, while the retrosigmoid approach has a lower incidence (3.7%). 9 Most patients tend to have an excellent recovery (House-Brackman of 1 or 2) though a minority of patients have permanent moderate dysfunction (House-Brackman of 3). 9 Tawfik et al 4 analyzed 291 patients who underwent VS surgery at their institution.…”

“… 9 Most patients tend to have an excellent recovery (House-Brackman of 1 or 2) though a minority of patients have permanent moderate dysfunction (House-Brackman of 3). 9 Tawfik et al 4 analyzed 291 patients who underwent VS surgery at their institution. They found that immediate facial palsy occurred in 21% (61) of patients whereas DFP occurred in 38% (112) of patients.…”

“…The incidence of DFP has been estimated to be between 5% to 25% with an average time of onset of 8.1 days. 4,[6][7][8][9] DFP is more likely to occur in patients who have larger VSs, lower intraoperative facial nerve stimulus responses, and lower rates of gross total resection. 9 Some studies have shown the translabyrinthine approach to have a higher incidence of DFP (15.3%) compared to the overall incidence, while the retrosigmoid approach has a lower incidence (3.7%).…”

“…4,[6][7][8][9] DFP is more likely to occur in patients who have larger VSs, lower intraoperative facial nerve stimulus responses, and lower rates of gross total resection. 9 Some studies have shown the translabyrinthine approach to have a higher incidence of DFP (15.3%) compared to the overall incidence, while the retrosigmoid approach has a lower incidence (3.7%). 9 Most patients tend to have an excellent recovery (House-Brackman of 1 or 2) though a minority of patients have permanent moderate dysfunction (House-Brackman of 3).…”

Transcanal Transpromontorial Approaches to the Internal Auditory Canal: A Systematic Review

“…45 For Koos-I to Koos-III schwannomas, recently reported rates of persistent postsurgical FN dysfunction range from 6.2% to 10.1% after the middle fossa approach, [46][47][48] retrosigmoid approach, 48-50 and 10.7%-16.4% after the translabyrinthine approach. 48,50 The pooled rates of persistent FN palsy after transpromontorial approaches for Koos-I to Koos-III schwannomas were higher (12.7%), likely due to the heterogeneous surgical experience with this recent approach across different institutions and the limited comprehensive number of treated patients. Different mechanisms have been accounted responsible for postoperative FN dysfunction, including thermal injury from the proximity of the light source during endoscopic surgery, mechanical injury from drilling bone adjacent to the tympanic segment, injury to the vascular supply of the FN, or traction injury during tumor dissection.…”