Facial nerve preservation in geniculate ganglion hemangiomas

Characteristics and Management of Facial Nerve Schwannomas and Hemangiomas

OBJECTIVES

To characterize facial nerve (FN) schwannomas (FNSs) and FN hemangiomas (FNHs) and their clinical features and management strategies, and to describe the results of cable nerve grafting after FN sectioning during tumor removal.

METHODS

This retrospective study included 84 FNS cases and 42 FNH cases managed between July 1989 and July 2020 at a quaternary referral center for skull base pathology. Clinical details, locations, management, and results of cable nerve grafting at 1 year and during an average period of 3.12 years were evaluated. Sural nerve interpositioning was performed for patients who experienced FN paralysis for less than 1 year and underwent nerve sectioning during tumor removal.

RESULTS

FNSs more often involved multiple segments compared with FNHs. The cerebellopontine angle and the mastoid segments were involved in 16 (19.1%) and 34 (40.5%) FNS cases, respectively; however, the cerebellopontine angle and the mastoid segments were involved in 0 and 7 (16.7%) FNH cases, respectively. Sectioned nerves of 99 patients (78.6%) were restored using interposition cable grafting. At the last follow-up evaluation, 56.3% of FNSs and 60.7% of FNHs attained House-Brackmann (HB) grade III. Lower preoperative HB grades were associated with poorer postoperative outcomes. For FNSs, the mean HB grades were 4.13 at 1 year postoperatively and 3.75 at the last follow-up evaluation ( p = 0.001); however, for FNHs, the mean HB grades were 4.04 postoperatively and 3.75 at the last follow-up evaluation. Therefore, extradural coaptation yielded better outcomes.

CONCLUSION

FNSs can occur along any part of the FN along its course, and FNHs are concentrated around the area of geniculate ganglion. The results of cable inter positioning grafts are better in patients with preoperative FN-HB-III or less when compared with higher grades. The outcome of the interpositioning continues to improve even after 1 year in extradural coaptation.

Differentiation of geniculate ganglion venous malformation from schwannoma: dynamic T1-weighted imaging provides unique diagnostic value

OBJECTIVE

To distinguish geniculate ganglion venous malformation (GGVM) from schwannoma (GGS) by using high-resolution CT (HRCT), routine MRI, and dynamic T1-weighted imaging (T1WI) characteristics.

METHODS

Surgically confirmed GGVMs and GGSs between 2016 and 2021 were retrospectively included. Preoperative HRCT, routine MR, and dynamic T1WI were performed on all patients. Clinical data, imaging characteristics including lesion size, involvement of facial nerve (FN), signal intensity, enhancement pattern on dynamic T1WI, and bone destruction on HRCT were evaluated. Logistic regression model was developed to identify independent factors for GGVMs, and the diagnostic performance was accessed by receiving operative curve (ROC) analysis. Histological characteristics were explored for both GGVMs and GGSs.

RESULTS

Twenty GGVMs and 23 GGSs with mean age of 31 were included. On dynamic T1WI, 18 GGVMs (18/20) showed "pattern A" enhancement (a progressive filling enhancement), while all 23 GGSs showed "pattern B" enhancement (a gradual whole-lesion enhancement) (p < 0.001). Thirteen GGVMs (13/20) showed the "honeycomb" sign whereas all GGS (23/23) showed extensive bone changes on HRCT (p < 0.001). Lesion size, involvement of FN segment, signal intensity on non-contrast T1WI and T2-weighted imaging (T2WI), and homogeneity on enhanced T1WI were obviously differed between two lesions (p < 0.001, p = 0.002, p < 0.001, p = 0.01, p = 0.02, respectively). Regression model showed the "honeycomb" sign and "pattern A" enhancement were independent risk factors. Histologically, GGVM was characterized by interwoven dilated and tortuous veins, while GGS was characterized by abundant spindle cells with dense arterioles or capillaries.

CONCLUSIONS

The "honeycomb" sign on HRCT and "pattern A" enhancement on dynamic T1WI are the most promising imaging characteristics for differentiating GGVM from GGS.

CLINICAL RELEVANCE STATEMENT

The characteristic sign and enhancement pattern on HRCT and dynamic T1-weighted imaging allow preoperative differentiation of geniculate ganglion venous malformation and schwannoma feasible, which will improve clinical management and benefit patient prognosis.

KEY POINTS

• The "honeycomb" sign on HRCT is a reliable finding to differentiate GGVM from GGS. • GGVM typically shows "pattern A" enhancement (focal enhancement of the tumor on early dynamic T1WI, followed by progressive contrast filling of the tumor in the delayed phase), while "pattern B" enhancement (gradual heterogeneous or homogeneous enhancement of the whole lesion) is observed in GGS on dynamic T1WI.

Surgical management of symptomatic hemangioma of the geniculate ganglion: fascicular-sparing resection or grafting?

Geniculate ganglion hemangioma (GGH) is rarely presented in the neurosurgical literature. It extends extradurally on the middle fossa floor and displaces the intratemporal part of the facial nerve. Surgical treatment is advisable at early symptoms. Proposed techniques include fascicular-sparing resection or nerve interruption with grafting. No definitive conclusions exist about the superiority of a certain technique in preserving facial nerve integrity and function. Through the description of a surgically managed symptomatic GGH, we herein discuss literature data about the surgical results of fascicular-sparing resection versus grafting. A PRISMA-based literature search was performed on the PubMed database. Only articles in English and published since 1990 were selected and furtherly filtered based on the best relevance. Statistical comparisons were performed with ANOVA. One hundred sixteen GGHs were collected, 56 were treated by fascicular-sparing resection, and 60 were treated by grafting. The facial function was improved, or unchanged, in 53 patients of the fascicular-sparing group and 30 patients of the grafting one. Sixty-five patients achieved a good (House-Brackmann (HB) grade III) postoperative facial outcome, of which 47 and 18 belonged to the fascicular-sparing and grafting group, respectively. Greater efficacy of the fascicular-sparing technique in the achievement of a better facial outcome was found (p = 0.0014; p = 0.0022). A surgical resection at the earliest symptoms is critical to preserve the facial nerve function in GGHs. Fascicular-sparing resection should be pursued in symptomatic cases with residual facial function (I-III HB). Conversely, grafting has a rationale for higher HB grades (V-VI). Broader studies are required to confirm these findings and turn them into new therapeutic perspectives.

Surgical Management of Intrinsic Tumors of the Facial Nerve

BACKGROUND

Intrinsic tumors of the facial nerve are a rare entity. Dealing with this subset of tumors is challenging both in terms of decision making and surgical intervention.

OBJECTIVE

To review the outcomes of surgical management of facial nerve tumors and cable nerve graft interpositioning.

METHODS

A retrospective analysis was performed at a referral center for skull base pathology. One hundred fifteen patients who were surgically treated for facial nerve tumors were included. In case of nerve interruption during surgery, the cable nerve interpositioning technique was employed wherein the facial nerve palsy lasted for less than 1-yr duration. In cases of facial nerve palsy lasting for greater than 1 yr, the nerve was restituted by a hypoglossal facial coaptation.

RESULTS

Various degrees of progressive paralysis were seen in 84 (73%) cases. Sixty nine (60%) of the tumors involved multiple segments of the facial nerve. Sixty-two (53.9%) tumors involved the geniculate ganglion. Seventy four (64.3%) of the cases were schwannomas. Hearing preservation surgeries were performed in 60 (52.1%). Ninety one (79.1%) of the nerves that were sectioned in association with tumor removal were restituted primarily by interposition cable grafting. The mean preoperative House-Brackmann grading of the facial nerve was 3.6. The mean immediate postoperative grading was 5.4, which recovered to a mean of 3.4 at the end of 1 yr.

CONCLUSION

In patients with good facial nerve function (House-Brackmann grade I-II), a wait-and-scan approach is recommended. In cases where the facial nerve has been interrupted during surgery, the cable nerve interpositioning technique is a convenient and well-accepted procedure for immediate restitution of the nerve.

A retrospective study on facial nerve schwannomas: a disease with a high risk of misdiagnosis and hearing loss

The objective is to increase awareness of facial nerve schwannomas (FNSs). Clinical data from 32 cases with FNSs who received surgical treatment from 2005 to 2015 were reviewed retrospectively. The clinical data included age, sex, presentations, duration, facial nerve function, temporal-bone high-resolution computed tomography (CT) and magnetic resonance imaging (MRI) findings, surgical approaches, and postoperative histopathological examination. 16 men and 16 women were included, aged 7-69 years. The average age at diagnosis was approximately 44 years. The mean duration of disease was 65 months, and the mean tumor diameter was 22.4 mm. A tendency of multisegment involvement was observed in 29 FNS cases. Geniculate ganglion and tympanic segments were the most commonly involved segments. Meanwhile, the incidence of misdiagnosis of this disease was 50%. We observed that when FNSs involved the proximal portion of genicular ganglion, the hearing function tended to be worse than when the FNSs only involved the genicular ganglion and/or its distal portion (p < 0.05); in such cases, the hearing loss tended to become more severe with a longer duration of the disorder (p < 0.05). Multiple segment involvement is common in patients with FNS. We need to be more aware of the hearing function when FNSs involve the proximal portion of genicular ganglion. Misdiagnoses of FNS are common, and patients can be misdiagnosed with Bell's palsy, otitis media, or other diseases. Image studies should be conducted for differential diagnosis. Once the decision to perform surgical resection was made, reconstruction of the facial nerve should be considered.

Management of Geniculate Ganglion Hemangiomas: Case Series and Systematic Review of the Literature

OBJECTIVE

To analyze facial nerve (FN) outcomes based on duration of FN palsy and surgical strategy in patients with geniculate ganglion hemangiomas (GGH).

STUDY DESIGN

Case series and systematic review of the literature.

SETTING

Tertiary care center.

SUBJECTS AND METHODS

All patients undergoing surgical resection of GGH from 1992 to 2014 were studied and a review of the English literature was performed.

RESULTS

One hundred twenty unique patients (mean age 41.4 yrs, 44% female) were identified with GGH: 8 in the current series and 112 from the literature review. Of these patients, 94% presented with FN weakness, 18% reported hemifacial spasm, and 16% had hearing loss at presentation. Eleven patients underwent an initial period of observation, 6 of which experienced either growth or progression of FN dysfunction. One hundred fourteen subjects ultimately underwent surgical intervention. The average preoperative House-Brackmann (HB) score was 4.6 and the mean duration of preoperative FN palsy was 27 months (range, 1-132). The average postoperative HB score was 3.5 at the last follow-up. Anatomical FN preservation was reported in 44% of patients. Duration of FN palsy ≤12 months was associated with better pre- and postoperative FN outcome (HB 4.1 vs 5.1, p = 0.01 and 2.9 vs 4.0, p < 0.001, respectively). FN preservation was also associated with better postoperative FN outcome compared with interposition grafting (HB 2.6 vs 3.9, p < 0.001).

CONCLUSION

GGHs are rare benign vascular malformations that present with progressive FN palsy. In most patients, early surgical intervention should be considered since shorter duration of FN paralysis and anatomical preservation of the FN are significant predictors of final FN outcome.