Transcanal endoscopic infracochlear vestibular neurectomy: A pilot cadaveric study.

PURPOSE: Effective operative approaches for the treatment of refractory vertigo in Meniere's disease are invasive. Vestibular neurectomy can preserve hearing and has been shown to be effective; however, current approaches require an extensive craniotomy. Transcanal endoscopic approaches to the internal auditory canal (IAC) with cochlear preservation have been recently described and may offer a minimally invasive approach to selectively sectioning the distal vestibular nerves while preserving residual hearing. MATERIALS AND METHODS: Three cadaveric human heads were imaged using high resolution computed tomography (CT). Anatomic analysis of preoperative CT scans showed adequate diameters (>3 mm) of the infracochlear surgical corridor for access to the IAC. A transcanal endoscopic approach was attempted to section the vestibular nerve. Post-operative CT scans were assessed to define the operative tract, determine cochlear preservation and assess cochlear and facial nerve preservation. RESULTS: Transcanal endoscopic approach was successfully performed (n = 3) using 3 mm-diameter, 14 cm-length 0°, 30°, and 45° endoscopes and microsurgical drills. In all cases the tympanomeatal flap and ossicular chain remained intact. Internal auditory canalotomy was performed using angled instruments and confirmed in real time via lateral skull base navigation. The vestibular nerves were readily identified and sectioned with preservation of the facial and cochlear nerves. Post-procedure CT showed no violation of the cochlea. CONCLUSION: A transcanal, infracochlear approach to the IAC may permit a minimally invasive approach to distal vestibular neurectomy in cadavers with appropriate anatomy.

Transcanal surgery for vestibular schwannomas: a pictorial review of radiological findings, surgical anatomy and comparison to the traditional translabyrinthine approach.

The most popular approaches for vestibular schwannoma (VS) removal are retrosigmoid, middle cranial fossa and translabyrinthine (TL). All require a certain degree of invasivity, bone removal, or brain manipulation. Recently, the authors described the transcanal transpromontorial approaches (TTA), which allow the inner ear to be accessed directly through the external auditory canal (EAC), either with a microscopic (Expanded TTA, or ExpTTA) or even an exclusive endoscopic technique (Endoscopic TTA, or EndoTTA). The advantages compared to traditional approaches are a direct view of the internal auditory canal (IAC) from lateral to medial, very little or no superficial tissue dissection and very little petrous bone drilling. In summary, from an anatomical point of view, they could be considered to be minimally invasive approaches. The radiologic outcome and the anatomical correspondence of these new approaches are described so as to share with the readers the possible radiologic findings and to compare and differentiate them from classic transpetrous approaches such as the TL approach. LEVEL OF EVIDENCE: 4.

Vertiginous syndrome associated with incorrect anesthesia technique to block the maxillary nerve via the greater palatine canal: case report and anatomic correlation with cadaveric parts / Síndrome vertiginoso asociado a técnica anestésica incorrecta para bloquear el nervio maxilar vía canal palatino mayor: reporte de caso y correlación anatómica en piezas cadavéricas

The anesthetic technique through the greater palatine canal seeks to block the maxillary nerve in the pterygopalatine fossa and anesthetize a large area, including the pulp and periodontium of the arch in question. After applying this technique in a patient, it failed to obtain the expected result. The patient began to experience dizziness, nausea, vomiting and the sensation of fluid in the ear. She was evaluated in both the emergency room of the Hospital Parroquial de San Bernardo and at a private clinic without accurate diagnosis. Only symptomatic treatment was provided. The next day she was discharged with reduced symptoms, which disappeared completely during the day. We propose the hypothesis of a diffusion of the anesthetic solution into the middle and inner ear through the auditory tube. This diffusion would explain the vestibular symptoms and the absence of anesthesia in the expected areas. We carried out an anatomic correlation in cadavers, following the path of a needle from the palatal mucosa to the pharyngeal opening of auditory tube. We conclude that the vertiginous syndrome could be due to an incorrect application of the technique, with the needle entering the auditory tube and spreading the anesthetic solution into the middle ear.

La técnica anestésica vía canal palatino mayor tiene como objetivo abordar al nervio maxilar en la fosa pterigopalatina, anestesiando un gran territorio, incluyendo la pulpa y periodonto de la hemiarcada correspondiente. Después de haber aplicado esta técnica en una paciente y no obteniendo el resultado esperado, esta comenzó a experimentar vértigo, náuseas, sensación de líquido en el oído y vómitos. Fue evaluada en el servicio de urgencias del Hospital Parroquial de San Bernardo y en una Clínica Privada, sin lograr un diagnóstico preciso y realizando solo un tratamiento sintomático. Al día siguiente fue dada de alta con baja sintomatología, la cual desapareció totalmente durante el día. Se propone la hipótesis de una difusión del anestésico hacia el oído medio e interno mediante el tubo auditivo. Esto explicaría por un lado la sintomatología vestibular y por otro la ausencia de anestesia en los dientes y territorios esperados. Además se realizó una correlación anatómica en cadáveres, utilizando 8 hemicabezas conservadas y siguiendo el posible trayecto de la aguja desde la mucosa palatina hasta el orificio faríngeo de la tuba auditiva. Se concluyó que el síndrome vertiginoso experimentado por la paciente se pudo deber a una técnica fallida al nervio maxilar vía canal palatino mayor con ingreso de la aguja al tubo auditivo, difundiendo el anestésico hacia el oído medio.