Giant vestibular schwannoma
Giant vestibular schwannoma if 4 cm or greater.
Giant vestibular schwannomas are seen in India due to the late diagnosis and long duration of symptoms before diagnosis 1). These giant schwannomas are challenging to manage as most of the patients are having brainstem compression.
Treatment
Case series
Clinical data of 61 patients with giant (≥4cm diameter) vestibular schwannomas undergoing craniotomy were retrospectively analyzed. These patients were divided into two cohorts, the first cohort including 35 patients with traditional retractor surgery from June 2016 to July 2017, the second cohort including 26 patients with retractorless surgery during June 2016 to July 2018.
Yao et al., compared the differences between the two groups as follows: the duration of operation, intraoperative blood loss, extent of resection (EOR), rate of facial nerve retention, postoperative brain injury rate, intracranial infection rate, hospitalization time and grade of facial nerve function.
For the comparison of the two groups, the incidence of brain injury was 3.84% in the retractorless group, which was obviously lower than the traditional group (22.86%) (P<0.05). No significant differences were found regarding the other items listed above.
Through appropriate comprehensive measures, retractorless surgery for giant vestibular schwannomas is an achievable goal, and this procedure can reduce the incidence of postoperative brain injury on the premise of satisfactory tumor resection 2).
Twelve cases of a giant vestibular schwannoma were operated between May 2011 and December 2012. Vestibular schwannomas with a maximal diameter of more than 4 cm were defined as a giant vestibular schwannoma. All the patients had a unilateral vestibular schwannoma. Performance status of all the patients were graded as per the Karnofsky performance score. Pre-operative assessment of 5(th), 7(th), 8(th) and lower cranial nerve status was done in all cases. Ventriculoperitoneal shunting was done pre-operatively in all cases. All patients were operated through retromastoid suboccipital craniectomy and retrosigmoid approach. These patients were operated in two stages in two consecutive days with overnight elective ventilation in ICU. Ultrasonic aspirator and nerve monitoring techniques were not used.
Giant acoustic schwannomas can be safely resected completely by a staged resection on two consecutive days without any increased morbidity or mortality. This technique may be employed to achieve complete resection of such lesions without deterioration of facial nerve function in institutions which do not have advanced facilities like nerve monitoring or ultrasonic aspirator 3).
Under the conditions of facial nerve monitoring, 400 patients with giant acoustic neuromas underwent microsurgical removal via suboccipital retrosigmoid approach between January 2005 and January 2013. There were 186 males and 214 females, with the age ranged from 15 to 74 years (mean, 41.6 years). The disease duration was 2-13 years (mean, 2.4 years). The lesions were located at the left cerebellopontine angle region (CPA) in 191 cases, right CPA in 200 cases, bilateral CPA in 9 cases. The clinical manifestations included unilateral hearing loss and tinnitus as first symptoms in 389 cases, facial numbness in 373 cases, unilateral facial paralysis in 370 cases, headache in 269 cases, lower cranial nerve symptoms with drinking cough and dysphagia in 317 cases, and unstable gait in 342 cases. Preoperative skull base thin layer CT showed varying degrees of horn -like expansion in ipsilateral internal auditory canal opening. MRI showed cysts in 78 cases and solid masses in 322 cases; with hydrocephalus in 269 cases. Postoperative cranial MRI or CT was taken to observe the extent of tumor resection. The preservation of facial nerves in anatomy was assessed by intraoperative microscope video and electrophysiological monitoring; the facial nerves function was assessed according to House-Brackmann (HB) classification on the first day after operation; and the rehabilitation of facial nerve function was also assessed at discharge and at 1 year postoperatively by using HB grade.
Total tumor removal was achieved in 372 cases (93.00%), and subtotal removal in 28 cases (7.00%). One case died of delayed brainstem ischemia at 14 days after operation, and 1 case died of lung infection at 20 days after operation; 398 cases were followed up 6 months to 8 years (mean, 3.5 years). Recurrence occurred in 1 case because of neurofibromatosis at 5 years after operation. The rate of anatomical preservation of the facial nerve during operation was 91.75% (367/400), and the functional preservation rate at the first day after operation was 62.75% (251/400). The HB grade of facial nerve function showed significant difference aomng 3 time points (at the first day, at discharge and at 1 year after operation) (chi2 = 23.432, P = 0.000). Complications included postoperative intracranial infection in 11 cases (2.75%), cerebrospinal fluid leakage in 29 cases (7.25%), aggravated lower cranial nerve symptoms in 18 cases (4.50%), subcutaneous effusion in 13 cases (3.25%), second operation to remove hematoma in 9 cases (2.25%), postoperative circumoral herpes simplex virus infection in 25 cases (6.25%), and all complications were cured after symptomatic treatment. Postoperative hydrocephalus disappeared in 261 cases 4).