Question of the Week - July 2022

 

July 13th, 2022

A 3-year-old male presents to the otology clinic for evaluation of hearing loss. An audiogram performed displays right-sided 20 dB conductive hearing loss with normal tympanograms bilaterally. Imaging studies show an abnormality of the stapes in the right ear. Which pharyngeal arch gives rise to the stapes?

A. 1st
B. 2nd
C. 3rd
D. 4th
E. 5th

  • B (3rd pharyngeal arch)

    Explanation: The 2nd pharyngeal arch (B) produces the stapes, styloid process, stylohyoid ligament, and parts of the hyoid.

    The 1st pharyngeal arch (A) gives rise to parts of the mandible, maxilla, malleus, incus, and the muscles of mastication.

    The 3rd arch (C) also contributes to the hyoid, along with the stylopharyngeus muscle.

    The 4th arch (D) gives rise to the laryngeal cartilages (e.g. thyroid, corniculate, cuneiform cartilages).

    The 5th pharyngeal arch (E) regresses in early development and does not become any adult structures.

    Reference: Casale J, Giwa AO. Embryology, Branchial Arches. In: StatPearls. Treasure Island (FL): StatPearls Publishing; August 11, 2021.

July 27th, 2022

An 18-year-old woman with a long history of severe deep ear pain for several months despite oral antibiotic treatment presents to the emergency department with worsening pain, headache, fever, and neck stiffness. Spinal fluid culture shows Streptococcus pneumoniae and she begins treatment with high-dose IV antibiotics. The next day, otolaryngology is consulted for a suspected left ear infection. Upon exam, significant purulent discharge is seen from the tympanic membrane along and a disconjugate gaze is noted. A CT scan is ordered and shows loss of air in the left mastoid and petrous tip but no intracranial abscess. She is scheduled for radical mastoidectomy that day for apparent petrous apicitis. Involvement of which of the following nerves is most likely the cause of her disconjugate gaze?

A. CN IV
B. CN III
C. CN VI
D. CN VIII

  • Quiz Answer: C (CN VI)

    Explanation: This patient with petrous apicitis is presenting with Gradenigo’s triad (suppurative otitis media, ipsilateral sixth (abducens) cranial nerve palsy and facial pain in the distribution of the fifth (trigeminal) cranial nerve). While involvement of other cranial nerves may occur, abducens palsy is most closely associated with the condition. When petrous apicitis is suspected, conventional imaging may show bone erosion and asymmetric clouding of the petrous tip. When the diagnosis of petrous apicitis is made, aggressive surgical drainage is indicated.

    Reference: Taklalsingh N, Falcone F, Velayudhan V. Gradenigo's Syndrome in a Patient with Chronic Suppurative Otitis Media, Petrous Apicitis, and Meningitis. Am J Case Rep. 2017;18:1039-1043. Published 2017 Sep 28. doi:10.12659/ajcr.904648