A-trains for intraoperative monitoring in patients with recurrent vestibular schwannoma.
Acta Neurochir (Wien)
; 155(12): 2273-9; discussion 2279, 2013 Dec.
Article
em En
| MEDLINE
| ID: mdl-24078065
ABSTRACT
BACKGROUND:
Second surgery of recurrent vestibular schwannoma (VS) after previous surgery, stereotactic radiosurgery (SR) or fractionated radiotherapy (FR) carries an increased risk for deterioration of facial nerve function, e.g., due to adhesions, underlining the need for intraoperative monitoring. Facial "Atrain" EMG activity ("traintime") correlates with the degree of postoperative facial palsy. Studies investigating A-trains in VS patients with previous surgery, SR or FR are missing. We therefore investigated the value of A-train monitoring in patients undergoing second surgery for VS.METHOD:
Intraoperative EMG data from patients who underwent second surgery for VS after previous surgery, SR and/or FR at our institution between 2006 and 2012 were retrospectively analyzed. Ten patients were selected (5 male) Seven had previous SR/RT and MS, three previous surgery only. Traintime values and distribution was compared to published thresholds and to 77 patients who underwent first surgery for VS during the same time period.RESULTS:
A-trains were recorded early after opening of the dura, before facial nerve preparation. Mean traintime was 46.9 s (18.51 s 80.82 s) in patients with previous SR/RT. In patients with previous MS only, traintime was 0.06 s, 0.99 s and 22.46 s. Compared to the literature, traintime was higher than expected in six patients (four with previous SR/RT, two without), respectively seven compared to the 77 patients with first surgery (5 SR/RT). Seven patients with previous SR/RT and none with previous surgery showed diffuse A-train distributions without significant percentages in single channels, compared to 60 of 77 patients with first surgery (p <0.02).CONCLUSIONS:
Especially SR/RT, but also previous surgery seems to induce changes in the facial nerve leading to hyperexcitability and exceedingly high traintime values. Based on these findings, A-train monitoring in this specific patient group should be interpreted with caution.
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Base de dados:
MEDLINE
Assunto principal:
Neuroma Acústico
/
Monitorização Intraoperatória
/
Nervo Facial
Tipo de estudo:
Observational_studies
/
Risk_factors_studies
Limite:
Adult
/
Aged
/
Female
/
Humans
/
Male
/
Middle aged
Idioma:
En
Revista:
Acta Neurochir (Wien)
Ano de publicação:
2013
Tipo de documento:
Article