The Experts below are selected from a list of 393 Experts worldwide ranked by ideXlab platform

Huang Weining - One of the best experts on this subject based on the ideXlab platform.

  • A clinical anatomical study on identification of the Internal Auditory Meatus in middle cranial fossa approach
    Chinese Archives of Otolaryngology-head and Neck Surgery, 2008
    Co-Authors: Huang Weining
    Abstract:

    OBJECTIVE The head of malleus (HOM) was regarded as the landmark for the middle cranial fossa approach,and its relationship with Internal Auditory Meatus(IAM) was measured. The purpose of this study was to find a safe method to locate IAM. METHODS Twelve heads of adult cadaver fixed with 10 % formaldehyde (23 sides) were microsurgically dissected from the middle cranial fossa approach. The foramen spinosum,Ferrein's foramen,greater petrosal nerve,lesser petrosal nerve,facial nerve,HOM,arcuate eminence,superior petrosal sinus,semicircular canal,and IAM were exposed. First,blue lines method was used to locate IAM. Second,HOM as the landmark was used to locate IAM. RESULTS The angles between the SSC and the longitude axis of IAM are 58.52°±4.84°。 A perpendicular line (AB) was drew from the center of HOM to the longitude axis of the temporal bone (the longitude axis of the superior petrosal sinus),line BC was drew from the anterior 30°(28.93°± 6.07°) to the line AB. On the line BC,fundus of IAM can be located (6.69±1.10) mm medial to HOM,the center of the Internal acoustic pore can be located (20.1±1.48)mm medial to HOM. CONCLUSION In the middle cranial fossa surgery,HOM can be used to locate IAM and its surroundings structures when traditional landmarks are unrecognized.

Kenji Sugiyama - One of the best experts on this subject based on the ideXlab platform.

  • surgical approach to the Internal Auditory Meatus in acoustic neuroma surgery significance of preoperative high resolution computed tomography
    Neurosurgery, 1996
    Co-Authors: Tetsuo Yokoyama, Kenichi Uemura, Hiroshi Ryu, Kaoru Hinokuma, Shigeru Nishizawa, Seiji Yamamoto, Mitsutoshi Endo, Kenji Sugiyama
    Abstract:

    OBJECTIVE AND METHOD : To establish a surgical approach that provides better access to the Internal Auditory Meatus (IAM) in acoustic tumor removal via a suboccipital transmeatal route, the anatomic location of the labyrinth with regard to the sigmoid-fundus line and the extent of bone removal from the IAM were evaluated by pre- and postoperative high-resolution computed tomography for 47 patients. RESULTS : The labyrinth was located lateral to the sigmoid-fundus line in 22 cases (lateral type, 46.8%), on the line in 9 (on-the-line type, 19.1%), and medial to the line in 16 (medial type, 34.0%). Postoperative high-resolution computed tomography showed that the mean length of the posterior wall from the fundus was shortened to 5.1 ± 1.1 mm (n = 27) in the partially resected group and to 2.0 ± 0.6 mm (n = 20) in the widely opened IAM group. The labyrinth was damaged in four cases from the widely opened IAM group ; the preoperative status of the labyrinth was medial to the sigmoid-fundus line in three and on the line in one. The cochlear nerve was preserved in seven (31%) partially resected and in eight (50%) widely opened IAM cases. The overall success rate of hearing preservation was 4 of 22 (18.2%) partially resected and 5 of 16 (31.2%) widely opened cases. CONCLUSION : Preoperative evaluation of the anatomic relation between the IAM and the labyrinth by high-resolution computed tomography provides an efficient surgical approach to the IAM and contributes to anatomic and functional preservation of the cochlear nerve.

Hidehiko Takeda - One of the best experts on this subject based on the ideXlab platform.

  • is a narrow Internal Auditory Meatus a contraindication to cochlear implants
    Cochlear Implants International, 2004
    Co-Authors: Kozo Kumakawa, Masahiro Takahashi, Hidehiko Takeda
    Abstract:

    The finding of an abnormality such as a narrow Internal Auditory Meatus (IAM) on computed tomography (CT) raises the possibility that the cochlear nerve may be aplastic or hypoplastic and non-functional. Shelton et al. (1989) reported that three children with the anomaly of narrow IAM had received cochlear implants but failed to show an Auditory response to sound stimulation. Since then, identification of this problem on screening image analysis has been a contraindication to cochlear implantation. However, Acker et al. (2001) mentioned that if definite responses to sound are present in either ear, implantation should be considered, even though imaging of the cochlear nerve is uncertain. We report that the promontory electrically evoked Auditory brainstem response (EABR) is useful in deciding the candidacy for cochlear implant even in cases with very poor sound responses, very narrow IAM (1–2 mm) and also an uncertain image of the cochlear nerve on magnetic resonance imaging (MRI).

Amey Savardekar - One of the best experts on this subject based on the ideXlab platform.

  • preservation of labyrinthine structures while drilling the posterior wall of the Internal Auditory canal in surgery of vestibular schwannomas via the retrosigmoid suboccipital approach
    World Neurosurgery, 2014
    Co-Authors: Amey Savardekar, Takashi Nagata, Kraiyot Kiatsoontorn, Yuzo Terakawa, Kenichi Ishibashi, Takeo Goto, Kenji Ohata
    Abstract:

    Objective To describe a new technique for safe drilling of the posterior wall of the Internal Auditory canal (IAC), in which the intact posterior lip of the Internal Auditory Meatus is used as a fixed intraoperative reference point to preserve the integrity of labyrinthine structures. Methods The retrosigmoid suboccipital approach was used to operate on 6 cases of vestibular schwannomas (Koos grade I and II), with preserved hearing. On a preoperative high-resolution computed tomography scan, a line starting 2 cm lateral to the lateral edge of the sigmoid sinus on the dura mater and directed tangential to the posterior semicircular canal or common crus was identified to intersect the posterior wall of the IAC. Drilling was carried out at a measured angle to the posterior petrous wall for meticulously measured distances, taking the intact posterior lip of the Internal Auditory Meatus as a fixed bony point. Results In the 6 cases, the mean length of the posterior wall of the IAC measured on the preoperative high-resolution computed tomography scan was 10.79 mm ± 1.87. By using our technique, the percentage of total length of the posterior wall of IAC drilled was 75.3% ± 20.5%. No injury to the posterior semicircular canal or common crus was observed intraoperatively. Total excision was performed in 5 patients, and near-total excision was performed in 1 patient. Functional hearing was preserved in all patients; testing was done 1 month after surgery. Conclusions Adequate drilling of the posterior wall of the IAC could be achieved, and tumor excision with hearing preservation was obtained by meticulous intraoperative planning and measurements based on preoperative computed tomography scanning and by keeping the intact posterior lip of the Internal Auditory Meatus as a landmark for safe drilling.

Toshihisa Murofushi - One of the best experts on this subject based on the ideXlab platform.

  • neuro otologic findings in unilateral isolated narrow Internal Auditory Meatus
    Otology & Neurotology, 2005
    Co-Authors: Ken Ito, Sayaka Suzuki, Toshihisa Murofushi, Shinichi Ishimoto, Shinichi Iwasaki, Shotaro Karino
    Abstract:

    Objective: To report neuro-otologic findings concerning the four nerves in the Internal Auditory Meatus (IAM) in patients with isolated congenitally narrow IAM and explore the implications regarding ontogeny of the nerves in the IAM. Design: Retrospective case series study. Setting: University hospital. Subjects: Five consecutive patients between 1997 and 2002 with unilateral isolated narrow IAM demonstrated by high-resolution computed tomography whose chief complaint was hearing loss (1 male and 4 females, 4 right sides and 1 left; age range 5-37 years, mean 20 years; IAM diameter at the porus: 26-33% of that on the normal side). Main Outcome Measures: Functional studies concerning the VIIth cranial nerve and the three branches of the VIIIth cranial nerve. Results: In all ears, Auditory brain stem responses were absent, the speech discrimination score was 0%, and otoacoustic emissions were absent or markedly reduced compared with those on the normal side. Caloric responses were absent in two ears, reduced in two ears, and normal in one ear. Galvanic body sway tests showed no responses in the two ears in which caloric responses were absent. Inferior vestibular nerve function was estimated as normal in all ears on the basis of vestibular evoked myogenic potential recordings. Facial nerve functions were normal in all patients. Conclusions: In isolated congenital stenosis of IAM, dysfunction of each nerve in the IAM can occur independently. In the ontogeny of the VIIIth cranial nerve, the cochlear and superior vestibular nerves tended to be involved together, whereas the cochlear and inferior vestibular nerves appeared independent of each other.

  • narrow Internal Auditory Meatus an idiopathic case confirming the origin and pathway of vestibular evoked myogenic potentials in humans
    Archives of Otolaryngology-head & Neck Surgery, 2001
    Co-Authors: Ken Ito, Shinichi Ishimoto, Toshihisa Murofushi
    Abstract:

    Objective To confirm the origin and pathway of vestibular evoked myogenic potentials (VEMPs) in humans. Design Case study. Setting University hospital. Patient A patient with a narrow Internal Auditory Meatus (IAM). Main Outcome Measures Imaging studies and functional studies concerning the seventh and eighth cranial nerves. Results Of the 4 nerves in the IAM, all but the cochlear nerve had normal function and normal courses, despite the pronounced narrowing of the IAM. The facial nerve had a normal diameter, but the vestibular nerves were thinner. Imaging revealed that the cochlear nerve was absent or extremely thinned. Both the cochlea and the cochlear nerve showed no function in the affected ear, although the VEMPs were evoked normally. Conclusion Our results definitively support the vestibular origin of VEMPs in humans.