Intraoperative brainstem auditory evoked potential observations after trigeminocardiac reflex during cerebellopontine angle surgery.
BACKGROUND
The occurrence of trigeminocardiac reflex (TCR) is known to be a negative prognostic factor for hearing preservation in cerebellopontine angle tumor surgery. Our study was conducted to investigate brainstem auditory evoked potential (BAEP) changes after this reflex in cerebellopontine angle tumor surgery and to evaluate their impact on postoperative hearing function.


METHODS
Five of 102 consecutive patients had an intraoperative TCR (4.9%) and were retrospectively evaluated for the intraoperative BAEP changes after TCR and postoperative auditory function (7 to 10 d after surgery). One of the 5 patients was preoperatively deaf and therefore excluded from this analysis.


RESULTS
Four patients with preoperative functional hearing developed one or more episodes of TCR. Intraoperative BAEP was maintained in 1 patient, whereas in 3 cases an acute intraoperative BAEP deterioration occurred within 2:04 to 3:27 minutes (mean 2:44 min) after TCR with increased wave latency, decreased wave amplitude, and even wave loss. Two patients had deteriorated BAEP waves until the surgical completion and were postoperatively deaf.


CONCLUSIONS
Although no direct cause-effect relationship has yet been shown, we suggest TCR as an additional event that may cause BAEP changes. The observed BAEP alterations occurred minutes rather than seconds after the TCR incident leading to both temporary and permanent wave deterioration. This association of BAEP deterioration and TCR occurrence, however, remains yet to be proven justifying further study in the field.
Acioly
Marcus André
MA
Department of Neurosurgery, Eberhard Karls University Hospital, Tübingen, Germany.
Carvalho
Carlos Henrique
CH
Koerbel
Andrei
A
Löwenheim
Hubert
H
Tatagiba
Marcos
M
Gharabaghi
Alireza
A
D000293:Adolescent; D000328:Adult; D000758:Anesthesia; D001301:Audiometry, Pure-Tone; D002528:Cerebellar Neoplasms / Q000473:pathology / Q000601:surgery; D002530:Cerebellopontine Angle / Q000601:surgery*; D004814:Epidermal Cyst / Q000601:surgery; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D006309:Hearing; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D008579:Meningioma / Q000601:surgery; D016343:Monitoring, Intraoperative; D009442:Neurilemmoma / Q000601:surgery; D011379:Prognosis; D012018:Reflex / Q000502:physiology*; D016896:Treatment Outcome; D014276:Trigeminal Nerve / Q000502:physiology*