title: The Role of MRI in Diagnosing Neurovascular Compression of the Cochlear Nerve Resulting in Typewriter Tinnitus.
abstract: OBJECTIVE
  Typewriter tinnitus, a symptom characterized by paroxysmal attacks of staccato sounds, has been thought to be caused by neurovascular compression of the cochlear nerve, but the correlation between radiologic evidence of neurovascular compression of the cochlear nerve and symptom presentation has not been thoroughly investigated. The purpose of this study was to examine whether radiologic evidence of neurovascular compression of the cochlear nerve is pathognomonic in typewriter tinnitus.
  
  
  METHODS
  Fifteen carbamazepine-responding patients with typewriter tinnitus and 8 control subjects were evaluated with a 3D T2-weighted volume isotropic turbo spin-echo acquisition sequence. Groups 1 (16 symptomatic sides), 2 (14 asymptomatic sides), and 3 (16 control sides) were compared with regard to the anatomic relation between the vascular loop and the internal auditory canal and the presence of neurovascular compression of the cochlear nerve with/without angulation/indentation.
  
  
  RESULTS
  The anatomic location of the vascular loop was not significantly different among the 3 groups (all,P> .05). Meanwhile, neurovascular compression of the cochlear nerve on MR imaging was significantly higher in group 1 than in group 3 (P= .032). However, considerable false-positive (no symptoms with neurovascular compression of the cochlear nerve on MR imaging) and false-negative (typewriter tinnitus without demonstrable neurovascular compression of the cochlear nerve) findings were also observed.
  
  
  CONCLUSIONS
  Neurovascular compression of the cochlear nerve was more frequently detected on the symptomatic side of patients with typewriter tinnitus compared with the asymptomatic side of these patients or on both sides of control subjects on MR imaging. However, considering false-positive and false-negative findings, meticulous history-taking and the response to the initial carbamazepine trial should be regarded as more reliable diagnostic clues than radiologic evidence of neurovascular compression of the cochlear nerve.
authors.affiliation: From the Departments of Radiology (Y.J.B., B.S.C.).
authors.forename: Y J
authors.identifier: http://orcid.org/0000-0002-1779-4949
authors.initials: YJ
authors.lastname: Bae
authors.affiliation: Otorhinolaryngology-Head and Neck Surgery (Y.J.J., J.-W.K., J.-J.S.), Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Y J
authors.identifier: http://orcid.org/0000-0002-0285-5534
authors.initials: YJ
authors.lastname: Jeon
authors.affiliation: From the Departments of Radiology (Y.J.B., B.S.C.).
authors.forename: B S
authors.identifier: http://orcid.org/0000-0001-6310-1798
authors.initials: BS
authors.lastname: Choi
authors.affiliation: Otorhinolaryngology-Head and Neck Surgery (Y.J.J., J.-W.K., J.-J.S.), Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: J-W
authors.identifier: http://orcid.org/0000-0002-5538-2785
authors.initials: JW
authors.lastname: Koo
authors.affiliation: Otorhinolaryngology-Head and Neck Surgery (Y.J.J., J.-W.K., J.-J.S.), Seoul National University Bundang Hospital, Seongnam, Korea. jjsong96@snubh.org jjsong96@gmail.com.
authors.forename: J-J
authors.identifier: http://orcid.org/0000-0002-6631-3232
authors.initials: JJ
authors.lastname: Song
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use; D002220:Carbamazepine / Q000627:therapeutic use; D002530:Cerebellopontine Angle / Q000000981:diagnostic imaging; D003056:Cochlear Nerve / Q000000981:diagnostic imaging*; D004424:Ear Canal / Q000000981:diagnostic imaging; D016057:Evoked Potentials, Auditory, Brain Stem; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014012:Tinnitus / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000209:etiology; D000160:Vestibulocochlear Nerve Diseases / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging*
chemical_list: D018712:Analgesics, Non-Narcotic; D002220:Carbamazepine