Facial nerve recovery following acoustic neuroma surgery

Effectiveness of Hypoglossal-Facial Anastomosis in the Rehabilitation of Facial Paralysis Following Vestibular Schwannoma Surgery: A Systematic Review

The facial nerve plays a crucial role in facial expression and sensory functions, with irreversible injuries often demanding rehabilitation therapies, with hypoglossal-facial nerve anastomosis (HFA) being one of the treatment options. This systematic review assessed different HFA techniques for facial paralysis, particularly post vestibular schwannoma resection, focusing on effectiveness and associated morbidities. Fifteen studies, comprising a case series and a retrospective cohort, were analyzed. Techniques included end-to-end, split, side-to-side, end-to-side, and jump interpositional graft hypoglossal-facial anastomosis (JIGHFA). Positive outcomes were observed with end-to-end and side-to-side techniques, while the split technique and JIGHFA showed promise. Comparative analyses favored the 'end-to-side' approach. Shorter intervals between surgery and HFA correlated with improved outcomes. Methodological variations highlight the need for prospective studies with standardized methodologies for robust evidence and informed decision-making on optimal HFA techniques.

Accuracy and outcomes of diffusion tensor imaging tractography in resection for vestibular schwannoma for facial nerve preservation

BACKGROUND

Impairment of facial nerve (FN) function is a common postoperative complication in surgical resections of Vestibular Schwannomas (VS). Diffusion tensor imaging (DTI) tractography creates in vivo imaging of the anatomical location of white matter tracts that can be preoperatively used to visualize the displaced FN. We present an analysis of patients who underwent DTI tractography imaging prior to VS resection.

METHODS

Patient charts were reviewed from March 2012 to April 2015 who underwent DTI tractography prior to surgical resection for VS. Reliability of this measure was compared to the intraoperative FN location as determined by the surgeon. House Brackmann (HB) score was used to assess facial nerve function.

RESULTS

A total of 11 patients were included with a mean age of 43 years (range: 19-64) and mean follow-up length of 11.9 months (range: 3.1-34.2). The average maximum tumor diameter was 2.82 cm (range: 1.7-4.2). DTI tractography was accurate in 90.9% (10/11) of patients. Postoperatively, 72.7% (8/11) had a HB score of I or II, 18.2% (2/11) had a HB score of III, and 9.1% (1/11) had a HB score of IV.

CONCLUSIONS

Facial nerve visualization for VS resection can be accurately visualized using DTI tractography. This modality may lead to reduction of postoperative FN damage.

Neuro-Ophthalmic Complications of Vestibular Schwannoma Resection: Current Perspectives

Vestibular schwannomas (VSs), also called acoustic neuromas, are benign intracranial neoplasms of the vestibulocochlear (VIII) cranial nerve. Management options include “wait-and-scan,” stereotactic radiosurgery and surgical resection. Due to the proximity of the VIII nerve to the facial (VII) nerve in the cerebello-pontine angle, the VII nerve is particularly vulnerable to the effects of surgical resection. This can result in poor eye closure, lagophthalmos and resultant corneal exposure post VS resection. Additionally, compression from the tumor or resection can cause trigeminal (V) nerve damage and a desensate cornea. The combination of an exposed and desensate cornea puts the eye at risk of serious ocular complications including persistent epithelial defects, corneal ulceration, corneal vascularization, corneal melting and potential perforation. The abducens (VI) nerve can be affected by a large intracranial VS causing raised intracranial pressure (a false localizing sign) or as a result of damage to the VI nerve at the time of resection. Other types of neurogenic strabismus are rare and typically transient. Contralaterally beating nystagmus as a consequence of vestibular dysfunction is common post-operatively. This generally settles to pre-operative levels as central compensation occurs. Ipsilaterally beating nystagmus post-operatively should prompt investigation for post-operative cerebrovascular complications. Papilledema (and subsequent optic atrophy) can occur as a result of a large VS causing raised intracranial pressure. Where papilledema follows surgical resection of a VS, it can indicate that cerebral venous sinus thrombosis has occurred. Poor visual function following VS resection can result as a combination of all these potential complications and is more likely with larger tumors.

Factors affecting final facial nerve outcome following vestibular schwannoma surgery

Objective:

To determine factors affecting facial nerve outcome of vestibular schwannoma surgery.

Methods:

This retrospective cohort study comprised 652 patients. The outcome measure was House–Brackmann classification at two years post-operatively. Univariate and multivariate analyses were carried out to determine the factors affecting facial nerve outcome. The incidence rates of hemifacial spasm, metallic taste and crocodile tear syndrome were recorded.

Results:

For tumours less than 1.5 cm, 95 per cent of outcomes were normal, 100 per cent were satisfactory (House–Brackmann grades I–III) and 0 per cent were unsatisfactory (grades IV–VI). For tumours 1.5–2.4 cm, 83 per cent of outcomes were normal, 99 per cent were satisfactory and 1 per cent were unsatisfactory. For tumours 2.5–3.4 cm, 68 per cent of outcomes were normal, 96 per cent were satisfactory and 4 per cent were unsatisfactory. For tumours 3.5–4.4 cm, 52 per cent of outcomes were normal, 80 per cent were satisfactory and 20 per cent were unsatisfactory. For tumours larger than 4.4 cm, 50 per cent of outcomes were normal, 72 per cent were satisfactory and 28 per cent were unsatisfactory.

Conclusion:

Tumour size and operation year were significant predictors of facial nerve outcome. The surgical learning curve was steepest for the first 50 patients.

Role of magnetic resonance imaging in predicting late facial motor function after removal of vestibular schwannomas by the translabyrinthine approach

Facial motor function was assessed in 61 patients 18 months after surgical resection, by the translabyrinthine approach, of vestibular schwannoma involving both the cerebellopontine angle (CPA) and the auditory canal. Pre-operative magnetic resonance imaging (MRI) was performed to measure the maximum extracanalicular diameter of the tumour between the porus and the farthest extension in the CPA on transverse slices and to calculate extracanalicular tumour volume. Post-operative facial motor function was graded according to the House and Brackmann system. There was a statistically significant relationship between late facial motor function and extracanalicular diameter. The best cut-off point for good and poor results was 20mm. There was no relationship between the tumour volume and the late post-operative facial motor function grade. In this study the best pre-operative radiological predictor of the late facial motor function in patients operated on by the translabyrinthine approach was the maximum diameter measured by MRI.

Results of acoustic neuroma surgery by the extended middle cranial fossa approach

The results of surgery in 160 cases of AN are reported. Surgery was carried out by the extended middle cranial fossa (EMCF) approach in 138 cases and by the middle cranial fossa (MCF) approach in 22 cases. The tumor extended an average of 28.9 mm into the posterior cranial fossa; 42% of the tumors extended 31 mm or more. Mortality was 1.9%. Of the 3 cases of death, two had large tumors of 45 mm and 52 mm each, and one was a case of recurrence. Total tumor removal was achieved in an average of 78.8% of the cases. When the cases were classified by date of operation, the total tumor removal rate in the 60 most recent cases was 93.3%. The rate of facial nerve presentation was 82.4% on average and 93% in the recent cases. Hypoglossal-facial nerve anastomosis was performed in 33% of the cases in which facial nerve function failed to recover for an extended period of time. Among recent cases, however, anastomosis has been carried out in 22% of the cases. Hearing was preserved in 20 cases. Useful hearing was preserved in 8 (38%) of 22 cases. Recurrence was confirmed through surgery in 3 cases. Recurrence was suspected but was unconfirmed in 3 cases.