An Easy and Reliable Method to Locate the Dehiscence during Middle Fossa Superior Canal Dehiscence Surgery: It is a (C)inch

Neil S. Patel, Jacob B. Hunter, Brendan P. O'Connell, George B. Wanna, Matthew L. Carlson

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Objective: The middle fossa floor lacks reliable surface landmarks. In cases of superior semicircular canal dehiscence (SSCD), multiple skull base defects may be present, further confounding the location of the labyrinth. Misidentification of the SSCD during surgery may lead to treatment failure or sensorineural hearing loss. Anecdotally, the authors have observed the distance from the lateral edge of the craniotomy to the SSCD to be consistently 1 inch. Herein, we present radiologic evidence of this practical and clinically useful relationship. Patients: All patients at two tertiary care academic referral centers with high-resolution temporal bone computed tomography (CT) evidence of SSCD were retrospectively reviewed. Intervention(s): Review of high-resolution temporal bone CT. Main Outcome Measures: The horizontal distance from the outer cortex of the squama temporalis immediately superior to the bony external auditory canal (approximating lateral edge of craniotomy) to the SSCD was measured in the coronal plane by two independent reviewers. Results: A total of 151 adult ears with SSCD were analyzed. A Shapiro-Wilk goodness-of-fit test confirmed that measurements were normally distributed. Pearson inter-rater correlation was 0.95, confirming very strong agreement. The mean distance between the outer cortex of the squama temporalis and SSCD was 25.9 mm, or 1.02 inches. Sixty-eight percent of the SSCD population would fall between 0.92 and 1.12 inches and 95% would lie between 0.83 and 1.21 inches. Conclusions: The horizontal distance from the outer cortex of the squama temporalis to the SSCD consistently approximates 1 inch. This easily remembered distance can aid surgeons in locating or confirming the SSCD during middle fossa surgery.

Original languageEnglish (US)
Pages (from-to)1092-1095
Number of pages4
JournalOtology and Neurotology
Volume37
Issue number8
DOIs
StatePublished - Sep 1 2016

Fingerprint

Semicircular Canals
Temporal Bone
Craniotomy
Tomography
Ear Canal
Sensorineural Hearing Loss
Skull Base
Inner Ear
Tertiary Healthcare
Treatment Failure
Ear
Referral and Consultation
Outcome Assessment (Health Care)

Keywords

  • Cranial base
  • Microsurgery
  • Middle fossa
  • Neurotology
  • Skull base
  • Superior semicircular canal dehiscence

ASJC Scopus subject areas

  • Otorhinolaryngology
  • Sensory Systems
  • Clinical Neurology

Cite this

An Easy and Reliable Method to Locate the Dehiscence during Middle Fossa Superior Canal Dehiscence Surgery : It is a (C)inch. / Patel, Neil S.; Hunter, Jacob B.; O'Connell, Brendan P.; Wanna, George B.; Carlson, Matthew L.

In: Otology and Neurotology, Vol. 37, No. 8, 01.09.2016, p. 1092-1095.

Research output: Contribution to journalArticle

Patel, Neil S. ; Hunter, Jacob B. ; O'Connell, Brendan P. ; Wanna, George B. ; Carlson, Matthew L. / An Easy and Reliable Method to Locate the Dehiscence during Middle Fossa Superior Canal Dehiscence Surgery : It is a (C)inch. In: Otology and Neurotology. 2016 ; Vol. 37, No. 8. pp. 1092-1095.
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abstract = "Objective: The middle fossa floor lacks reliable surface landmarks. In cases of superior semicircular canal dehiscence (SSCD), multiple skull base defects may be present, further confounding the location of the labyrinth. Misidentification of the SSCD during surgery may lead to treatment failure or sensorineural hearing loss. Anecdotally, the authors have observed the distance from the lateral edge of the craniotomy to the SSCD to be consistently 1 inch. Herein, we present radiologic evidence of this practical and clinically useful relationship. Patients: All patients at two tertiary care academic referral centers with high-resolution temporal bone computed tomography (CT) evidence of SSCD were retrospectively reviewed. Intervention(s): Review of high-resolution temporal bone CT. Main Outcome Measures: The horizontal distance from the outer cortex of the squama temporalis immediately superior to the bony external auditory canal (approximating lateral edge of craniotomy) to the SSCD was measured in the coronal plane by two independent reviewers. Results: A total of 151 adult ears with SSCD were analyzed. A Shapiro-Wilk goodness-of-fit test confirmed that measurements were normally distributed. Pearson inter-rater correlation was 0.95, confirming very strong agreement. The mean distance between the outer cortex of the squama temporalis and SSCD was 25.9 mm, or 1.02 inches. Sixty-eight percent of the SSCD population would fall between 0.92 and 1.12 inches and 95{\%} would lie between 0.83 and 1.21 inches. Conclusions: The horizontal distance from the outer cortex of the squama temporalis to the SSCD consistently approximates 1 inch. This easily remembered distance can aid surgeons in locating or confirming the SSCD during middle fossa surgery.",
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AU - Hunter, Jacob B.

AU - O'Connell, Brendan P.

AU - Wanna, George B.

AU - Carlson, Matthew L.

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AB - Objective: The middle fossa floor lacks reliable surface landmarks. In cases of superior semicircular canal dehiscence (SSCD), multiple skull base defects may be present, further confounding the location of the labyrinth. Misidentification of the SSCD during surgery may lead to treatment failure or sensorineural hearing loss. Anecdotally, the authors have observed the distance from the lateral edge of the craniotomy to the SSCD to be consistently 1 inch. Herein, we present radiologic evidence of this practical and clinically useful relationship. Patients: All patients at two tertiary care academic referral centers with high-resolution temporal bone computed tomography (CT) evidence of SSCD were retrospectively reviewed. Intervention(s): Review of high-resolution temporal bone CT. Main Outcome Measures: The horizontal distance from the outer cortex of the squama temporalis immediately superior to the bony external auditory canal (approximating lateral edge of craniotomy) to the SSCD was measured in the coronal plane by two independent reviewers. Results: A total of 151 adult ears with SSCD were analyzed. A Shapiro-Wilk goodness-of-fit test confirmed that measurements were normally distributed. Pearson inter-rater correlation was 0.95, confirming very strong agreement. The mean distance between the outer cortex of the squama temporalis and SSCD was 25.9 mm, or 1.02 inches. Sixty-eight percent of the SSCD population would fall between 0.92 and 1.12 inches and 95% would lie between 0.83 and 1.21 inches. Conclusions: The horizontal distance from the outer cortex of the squama temporalis to the SSCD consistently approximates 1 inch. This easily remembered distance can aid surgeons in locating or confirming the SSCD during middle fossa surgery.

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KW - Microsurgery

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KW - Neurotology

KW - Skull base

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