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Daniele Starnoni, Roy Thomas Daniel, Constantin Tuleasca, Mercy George, Marc Levivier, and Mahmoud Messerer

OBJECTIVE

During the last decade, the primary objective for large vestibular schwannoma (VS) management has progressively shifted, from tumor excision to nerve preservation by using a combined microsurgical and radiosurgical approach. The aim of this study was to provide a systematic review and meta-analysis of the available literature regarding the combined strategy of subtotal resection (STR) followed by stereotactic radiosurgery (SRS) for large VSs.

METHODS

The authors performed a systematic review and meta-analysis in compliance with the PRISMA guidelines for article identification and inclusion using the PubMed, Embase, and Cochrane databases. Established inclusion criteria were used to screen all identified relevant articles published before September 2017 without backward date limit.

RESULTS

The authors included 9 studies (248 patients). With a weighted mean follow-up of 46 months (range 28–68.8 months), the pooled rate of overall tumor control was 93.9% (95% CI 91.0%–96.8%). Salvage treatment (second STR and/or SRS) was necessary in only 13 (5.24%) of 18 patients who experienced initial treatment failure. According to the House-Brackmann (HB) grading scale, functional facial nerve preservation (HB grade I–II) was achieved in 96.1% of patients (95% CI 93.7%–98.5%). Serviceable hearing after the combined approach was preserved in 59.9% (95% CI 36.5%–83.2%).

CONCLUSIONS

A combined approach of STR followed by SRS was shown to have excellent clinical and functional outcomes while still achieving a tumor control rate comparable to that obtained with a total resection. Longer-term follow-up and larger patient cohorts are necessary to fully evaluate the rate of tumor control achieved with this approach.

Free access

Constantin Tuleasca, Mercy George, Mohamed Faouzi, Luis Schiappacasse, Henri-Arthur Leroy, Michele Zeverino, Roy Thomas Daniel, Raphael Maire, and Marc Levivier

OBJECTIVE

Vestibular schwannomas (VSs) represent a common indication of Gamma Knife surgery (GKS). While most studies focus on the long-term morbidity and adverse radiation effects (AREs), none describe the acute clinical AREs that might appear on a short-term basis. These types of events are investigated, and their incidence, type, and outcomes are reported in the present paper.

METHODS

The included patients were treated between July 2010 and March 2016, underwent at least 6 months of follow-up, and presented with a disabling symptom during the first 6 months after GKS that affected their quality of life. The timing of appearance, as well as the type of main symptom and outcome, were noted. The prescribed dose was 12 Gy at the margin.

RESULTS

Thirty-five (22%) of 159 patients who fulfilled the inclusion criteria had acute clinical AREs. The mean followup period was 30 months (range 6–49.2 months). The mean time of appearance was 37.9 days (median 31 days; range 3–110 days). In patients with de novo symptoms, the more frequent symptoms were vertigo (n = 4; 11.4%) and gait disturbance (n = 3; 8.6%). The exacerbation of a preexisting symptom was more frequently related to hearing loss (n = 10; 28.6%), followed by gait disturbance (n = 7; 20%) and vertigo (n = 3, 8.6%). In the univariate logistic regression analysis, the following factors were statistically significant: age (p = 0.002; odds ratio [OR] 0.96), hearing at baseline by Gardner-Robertson (GR) class (p = 0.006; OR 0.21), pure tone average at baseline (p = 0.006; OR 0.97), and Koos grade at baseline (with Koos Grade I used as a reference) (for Koos Grade II, OR 0.17 and p = 0.002; for Koos Grade III, OR 0.42 and p = 0.05). The following were not statistically significant but showed a tendency toward significance: the number of isocenters (p = 0.06; OR 0.94) and the maximal dose received by the cochlea (p = 0.07; OR 0.74). Fractional polynomial regression analysis showed a nonlinear relationship between the outcome and the radiation dose rate (minimum reached at a cutoff of 2.5 Gy/minute) and the maximal vestibular dose (maximum reached at a cutoff of 8 Gy), but the small sample size precludes a detailed analysis of the former. The clinical acute AREs disappeared in 32 (91.4%) patients during the first 6 months after appearance. Permanent and somewhat disabling morbidity was found in 3 cases (1.9% from the whole series): 1 each with complete hearing loss (GR Class I before and V after), hemifacial spasm (persistent but alleviated), and dysgeusia.

CONCLUSIONS

Acute effects after radiosurgery for VS are not rare. They concern predominantly de novo vertigo and gait disturbance and the exacerbation of preexistent hearing loss. In de novo vestibular symptoms, a vestibular dose of more than 8 Gy is thought to play a role. In most cases, none of these effects are permanent, and they will ultimately improve or disappear with steroid therapy. Permanent AREs remain very rare.

Restricted access

Daniele Starnoni, Giulia Cossu, Rodolfo Maduri, Constantin Tuleasca, Mercy George, Raphael Maire, Mahmoud Messerer, Marc Levivier, Etienne Pralong, and Roy T. Daniel

OBJECTIVE

Cochlear nerve preservation during surgery for vestibular schwannoma (VS) may be challenging. Brainstem auditory evoked potentials and cochlear compound nerve action potentials have clearly shown their limitations in surgeries for large VSs. In this paper, the authors report their preliminary results after direct electrical intraoperative cochlear nerve stimulation and recording of the postauricular muscle response (PAMR) during resection of large VSs.

METHODS

The details for the electrode setup, stimulation, and recording parameters are provided. Data of patients for whom PAMR was recorded during surgery were prospectively collected and analyzed.

RESULTS

PAMRs were recorded in all patients at the ipsilateral vertex-earlobe scalp electrode, and in 90% of the patients they were also observed in the contralateral electrode. The optimal stimulation intensity was found to be 1 mA at 1 Hz, with a good cochlear response and an absent response from other nerves. At that intensity, the ipsilateral cochlear response had an initial peak at a mean (± SEM) latency of 11.6 ± 1.5 msec with an average amplitude of 14.4 ± 5.4 µV. One patient experienced a significant improvement in his audition, while that of the other patients remained stable.

CONCLUSIONS

PAMR monitoring may be useful in mapping the position and trajectory of the cochlear nerve to enable hearing preservation during surgery.

Restricted access

Ann Mansur, Benjamin Morgan, Alexandre Lavigne, Nicolas Phaneuf-Garand, Jocelyne Diabira, Han Yan, Unni G. Narayanan, Darcy Fehlings, Golda Milo-Manson, Blythe Dalziel, Sara Breitbart, Claude Mercier, Dominic Venne, Pierre Marois, Alexander G. Weil, Jeffrey S. Raskin, Sruthi P. Thomas, and George M. Ibrahim

OBJECTIVE

In nonambulatory children with predominantly spastic cerebral palsy (CP), the authors compared care needs, symptom burden, and complications after surgical treatment with either intrathecal baclofen (ITB) pump insertion or selective dorsal rhizotomy (SDR). The patients were treated at two Canadian centers with variability in practice pertaining to these surgical options.

METHODS

The authors performed a retrospective analysis of nonambulatory children with predominantly spastic quadriplegic or diplegic CP who underwent treatment with ITB or SDR. These two strategies were retrospectively assessed by comparing patient data from the two treatment groups for demographic characteristics, outcomes, and complications. A partial least-squares analysis was performed to identify patient phenotypes associated with outcomes.

RESULTS

Thirty patients who underwent ITB and 30 patients who underwent SDR were included for analysis. Patients in the ITB group were older and had lower baseline functional status, with greater burdens of spasticity, dystonia, pain, deformity, bladder dysfunction, and epilepsy than patients in the SDR group. In addition, children who underwent SDR had lower Gross Motor Function Classification System (GMFCS) levels and were less likely to experience complications than those who underwent ITB. However, children treated with SDR had fewer improvements in pain than children treated with ITB. A single significant latent variable explaining 88% of the variance in the data was identified.

CONCLUSIONS

Considerable baseline differences exist within this pediatric CP patient population. Factors specific to individual children must be taken into account when determining whether ITB or SDR is the appropriate treatment.