Surgical treatment of large vestibular schwannomas with hydrocephalus in octogenarians: Two cases with favorable functional outcomes

Abstract

Background:

The optimal management of vestibular schwannoma (VS) associated with hydrocephalus in octogenarians remains controversial. We report two patients aged 80 years or older with Koos grade IV VS who underwent surgical treatment.

Case Description:

Case 1 involved an 86-year-old woman who presented with progressive gait disturbance caused by a 3.5-cm cystic right VS associated with hydrocephalus. Case 2 involved an 81-year-old woman who presented with cognitive impairment and gait disturbance due to a 3.0-cm cystic left VS with hydrocephalus. In both patients, magnetic resonance imaging demonstrated narrowing of the high-convexity sulci, enlarged Sylvian fissures, and an acute callosal angle. Tumor resection was performed via a retrosigmoid approach with intraoperative facial motor evoked potential (FMEP) monitoring. Tumor dissection was terminated when FMEP amplitudes decreased to <50% of baseline values, resulting in subtotal or near-total tumor resection. Neither patient developed clinically significant postoperative facial nerve dysfunction. Both patients regained independent ambulation. Postoperative imaging demonstrated reduction of ventricular enlargement and improvement of hydrocephalus-related radiological findings. Cognitive function improved substantially in Case 2, with the Mini-Mental State Examination score increasing from 11 to 24. At the latest follow-up, the first patient remained independent without tumor progression or recurrent hydrocephalus 5.9 years after surgery, whereas the second patient maintained independent daily functioning without evidence of tumor progression at 8 months postoperatively.

Conclusion:

Surgical resection with intraoperative facial nerve monitoring may provide favorable functional and radiological outcomes in carefully selected octogenarians with large VSs associated with hydrocephalus.

INTRODUCTION

Vestibular schwannoma (VS) is a common benign tumor of the cerebellopontine angle, and hydrocephalus occurs in approximately 9–15% of patients, particularly in those with large tumors and higher Koos grades.[2,9,10,12] Both obstructive and communicating hydrocephalus have been described, and elevated cerebrospinal fluid (CSF) protein levels and impaired CSF absorption have been proposed as underlying mechanisms.[7,10,13,17]

The optimal management of VS-associated hydrocephalus remains controversial. While primary tumor resection frequently results in resolution of hydrocephalus, some authors advocate CSF diversion before surgery, particularly in elderly patients.[2,10,12] Furthermore, stereotactic radiosurgery may itself be associated with communicating hydrocephalus in selected patients.[4,15]

Treatment of VS in octogenarians (patients aged 80 years or older) is particularly challenging because advanced age often favors conservative management. However, recent studies have demonstrated acceptable surgical outcomes in carefully selected elderly patients.[16,19] Zhang et al. reported that elderly patients more frequently presented with hydrocephalus and balance disturbance but achieved favorable long-term outcomes after microsurgery, suggesting that advanced age alone should not be considered a contraindication to surgery.[19]

In addition, intraoperative facial motor evoked potential (FMEP) monitoring has been shown to predict postoperative facial nerve function.[1,5,8,11,14] We report two patients over 80 years of age with Koos grade IV VSs associated with hydrocephalus who underwent tumor resection with intraoperative facial nerve monitoring and achieved favorable functional outcomes.

CASE PRESENTATION

Case 1

An 86-year-old woman presented with progressive gait disturbance. The patient had no significant medical history and had been living independently at home. At presentation, the patient had complete hearing loss in the right ear, although the onset was unknown. Her preoperative Karnofsky Performance Status (KPS) score was 40, and her modified 5-item frailty index (mFI-5) was 1.[18] Magnetic resonance imaging (MRI) demonstrated a cystic tumor measuring 3.5 cm in maximum diameter in the right cerebellopontine angle [Figure 1A]. Coronal T1-weighted MRI showed ventriculomegaly, narrowing of the callosal angle (69°), enlargement of the inferior horns of the lateral ventricles, narrowing of the high-convexity sulci, and enlargement of the Sylvian fissures [Figure 1B], findings consistent with communicating hydrocephalus with imaging features resembling disproportionately enlarged subarachnoid-space hydrocephalus (DESH).

Figure 1:

Case 1. (A) Preoperative magnetic resonance imaging (MRI) Constructive Interference in Steady State (CISS) image demonstrating a vestibular schwannoma (VS) (arrow). (B) Preoperative coronal T1-weighted MRI demonstrating ventriculomegaly, narrowing of the callosal angle, enlargement of the inferior horns of the lateral ventricles, narrowing of the high-convexity sulci, and enlargement of the Sylvian fissures. (C) MRI CISS image obtained after surgery showing the residual VS (arrow). Approximately 95% of the tumor was resected. (D) Computed tomography obtained 3 years after surgery demonstrating improvement of ventriculomegaly, widening of the callosal angle, reduction of the enlarged inferior horns of the lateral ventricles, reopening of the high-convexity sulci, and reduction of the Sylvian fissures.

Despite her advanced age, she had no significant comorbidities and was otherwise in good general health; therefore, surgery was performed. Tumor resection was performed via a retrosigmoid approach. Intraoperative facial nerve monitoring was conducted using transcranial facial FMEPs (TcFMEPs) and direct electrical stimulation mapping. Tumor dissection from the facial nerve was discontinued when the TcFMEP amplitude decreased to <50% of the baseline value, resulting in approximately 95% tumor removal.

No postoperative facial nerve palsy developed (House-Brackmann grade I). The patient’s gait gradually improved, and she was transferred to a rehabilitation hospital. Three months after surgery, she was discharged and was able to visit our outpatient clinic independently without the use of a cane or assistance. She subsequently resumed independent living at home.

Follow-up MRI after surgery demonstrated a small residual tumor without evidence of regrowth [Figure 1C]. Follow-up imaging demonstrated improvement of ventriculomegaly, with the Evans index decreasing from 0.35 preoperatively to 0.32 postoperatively. The callosal angle widened from 69° preoperatively to 118° postoperatively. In addition, reduction of the enlarged inferior horns of the lateral ventricles, reopening of the high-convexity sulci, and reduction of the Sylvian fissures were observed [Figure 1D], indicating marked improvement of hydrocephalus. Annual MRI examinations showed neither tumor progression nor recurrence of hydrocephalus. At the last follow-up, 5 years and 9 months after surgery, the patient remained ambulatory without assistance, continued to live independently at home (KPS score, 80), and showed no evidence of tumor progression.

Case 2

An 81-year-old woman had experienced progressive left-sided hearing loss for 1 year. The patient had been receiving medication for hypercholesterolemia and hypertension. Six months before this visit, the patient had been hospitalized for a lumbar compression fracture. Two months before presentation, she developed progressive cognitive impairment and gait disturbance. MRI revealed a cystic tumor measuring 3 cm in maximum diameter extending from the left internal auditory canal to the cerebellopontine angle [Figure 2A and B]. Coronal T1-weighted MRI demonstrated ventriculomegaly, narrowing of the callosal angle (81°), enlargement of the inferior horns of the lateral ventricles, narrowing of the high-convexity sulci, and enlargement of the Sylvian fissures [Figure 2C], findings consistent with communicating hydrocephalus and imaging features resembling DESH.

Figure 2:

Case 2. (A) Preoperative magnetic resonance imaging (MRI) Constructive Interference in Steady State image demonstrating a vestibular schwannoma (arrow). (B) Preoperative gadolinium-enhanced T1-weighted MRI demonstrating a vestibular schwannoma (arrow). (C) Preoperative coronal T1-weighted MRI demonstrating ventriculomegaly, narrowing of the callosal angle, enlargement of the inferior horns of the lateral ventricles, narrowing of the high-convexity sulci, and enlargement of the Sylvian fissures. (D) Postoperative gadolinium-enhanced T1-weighted MRI showing near-total tumor resection and enhancement of the facial nerve (arrow). (E) Postoperative Computed tomography demonstrating improvement of ventriculomegaly compared with the preoperative image, widening of the callosal angle, reduction of the enlarged inferior horns of the lateral ventricles, reopening of the high-convexity sulci, and reduction of the Sylvian fissures.

Her Mini-Mental State Examination (MMSE) score at presentation was 11, and she required a wheelchair because of severe gait impairment. Her preoperative KPS score was 40, and her mFI-5 was 2.

Despite her advanced age, she had no significant comorbidities and was otherwise in good general health; therefore, surgery was performed. Tumor resection was performed via a retrosigmoid approach. Intraoperative facial nerve monitoring was conducted using TcFMEPs and direct electrical stimulation mapping. After the tumor had been largely removed, the amplitude of the orbicularis oculi TcFMEP decreased by 50% from the baseline value during dissection of the remaining tumor from the facial nerve. Therefore, the tumor was resected with a portion of the capsule intentionally left attached to the facial nerve. Near-total resection was achieved, leaving only a thin layer of the tumor cyst wall adherent to the facial nerve, as demonstrated on postoperative gadolinium-enhanced MRI [Figure 2D].

Postoperative MRI obtained 3 months after surgery demonstrated improvement of ventriculomegaly (Evans index 0.34 preoperative to 0.31 postoperative), widening of the callosal angle (81° preoperative to 93° postoperative), reduction of the enlarged inferior horns of the lateral ventricles, reopening of the high-convexity sulci, and reduction of the Sylvian fissures [Figure 2E], indicating marked improvement of hydrocephalus.

No postoperative facial nerve palsy developed (House– Brackmann grade I). The patient was subsequently transferred to a rehabilitation hospital and discharged 2 months later. At outpatient follow-up, she was able to walk independently without a cane or assistance and returned to independent living at home (KPS score, 70). Her MMSE score improved to 24, indicating substantial cognitive recovery.

DISCUSSION

Our cases demonstrate that surgical treatment can provide favorable outcomes even in patients over 80 years of age with large VSs associated with hydrocephalus. Both patients experienced marked improvement in gait disturbance and functional independence after tumor removal.

Hydrocephalus is reported in approximately 9–15% of patients with VS and is associated with larger tumors and higher Koos grades.2–5 Elevated CSF protein levels and impaired CSF absorption have been proposed as mechanisms underlying communicating hydrocephalus.[7,10,13] Previous studies have shown that hydrocephalus resolves after primary tumor removal in most patients, with only a minority requiring permanent shunting.[12] Conversely, some authors advocate initial CSF diversion in selected patients.[10]

In both patients, MRI demonstrated DESH-like features, including narrowing of the callosal angle, tight high-convexity sulci, and enlargement of the Sylvian fissures. Similar imaging findings have been reported in VS-associated communicating hydrocephalus. Murai et al. found that DESH-like features were frequently observed in patients with VS and hydrocephalus and suggested that impaired CSF absorption may contribute to this condition.[17]

The DESH-like findings in our patients improved after tumor removal, suggesting that VS-associated communicating hydrocephalus may share pathophysiological mechanisms with DESH. Recognition of these imaging features may therefore be important, particularly in elderly patients presenting with gait disturbance and cognitive impairment.

Management of elderly patients remains challenging. Lefevre et al. demonstrated acceptable outcomes in octogenarians undergoing VS surgery, suggesting that advanced age alone should not preclude surgical treatment.[16] Similarly, Zhang et al. reported that elderly patients had a higher incidence of hydrocephalus and balance disorders and experienced slower postoperative recovery; nevertheless, long-term functional outcomes were favorable despite poorer preoperative conditions and greater comorbidity.[19] These findings support surgical treatment in carefully selected elderly patients.

Frailty assessment is also important when considering surgery in this population. The mFI-5 is a simple risk-stratification tool based on congestive heart failure, diabetes mellitus, chronic obstructive pulmonary disease or pneumonia, dependent functional status, and hypertension requiring medication; higher scores are associated with increased postoperative morbidity.[18] In our patients, the mFI-5 scores were 1 and 2, with functional dependence largely attributable to hydrocephalus. The relatively low burden of the other frailty components may have contributed to their favorable postoperative outcomes despite advanced age.

Earlier MRI evaluation of persistent unilateral hearing loss may facilitate the diagnosis of VS before the development of complications such as hydrocephalus. Although most VSs in elderly patients are slow-growing and can be managed conservatively, earlier diagnosis may provide a broader range of management options, including observation or stereotactic radiosurgery.[3,6] However, radiosurgery may increase the risk of communicating[3,6] hydrocephalus in selected patients, particularly in older individuals and those with larger tumors.[4,15] In the present cases, both patients had symptomatic hydrocephalus and large cystic tumors, making surgical decompression an appropriate treatment strategy.

Facial nerve preservation is a major goal in the surgical treatment of large VSs. Multiple studies have demonstrated that intraoperative FMEP monitoring predicts postoperative facial nerve function.[1,5,8,11,14] Although Della Pepa et al. reported that the optimal FMEP cutoff values varied according to the recorded muscle and the timing of postoperative assessment, all reported thresholds were below 50% of the baseline amplitude.[8] Therefore, a 50% reduction in FMEP amplitude may represent a relatively safe and conservative warning threshold for intraoperative facial nerve monitoring. In our cases, dissection was terminated when the FMEP amplitude decreased below 50% of the baseline value, which may have contributed to preservation of facial nerve function.

CONCLUSION

Although limited to two cases, this report suggests that carefully selected octogenarians with symptomatic Koos grade IV VSs and hydrocephalus may benefit from surgical treatment, with favorable long-term functional outcomes.

Ethical approval:

The research/study was approved by the Institutional Review Board at Kansai Medical University, number 2020055, dated August 28, 2020.

Declaration of patient consent:

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for their images and other clinical information to be reported in the journal. The patient understands that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The author(s) confirms that they have used artificial intelligence (AI)-assisted technology. ChatGPT was used to assist with the English proofreading of this manuscript.

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