1 / 20

The Large Vestibular Aqueduct Syndrome in adults

The Large Vestibular Aqueduct Syndrome in adults. an almost understimated realm Dr. Dieter Goettmann Stuttgart University Medical Centers Groningen, Nijmegen. Preface. LVAS is a syndrom Sensorineural hearing loss Sudden Fluctuating Progressive Imaging subsidary. Anatomy – Historic.

hua
Download Presentation

The Large Vestibular Aqueduct Syndrome in adults

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Large Vestibular Aqueduct Syndrome in adults an almost understimated realm Dr. Dieter Goettmann Stuttgart University Medical Centers Groningen, Nijmegen

  2. Preface • LVAS is a syndrom • Sensorineural hearing loss • Sudden • Fluctuating • Progressive • Imaging subsidary

  3. Anatomy – Historic E.Pernkopf: Atlas der topographischen Anatomie des Menschen, Bd.IV,München 1960, Tafel 162

  4. Anatomy - Terminology • Endolymphatic sac • Extraosseus part • Intraosseus part • Commonly interpretated as the endoymphatic duct • Preductal • Endolymphatic duct • Small & short • Alsmost never dilatated

  5. Anatomy – Terminology Intraosseus Part External Aperture of Vestibular Aqueduct Extraosseus Part of Endolymphatic Sac

  6. Endolymph Unique extracellular fluid • High potassium: 157 mM (CSF: 3.1 mM) • Paramagnetic • Low sodium: 1.3 mMol (CSF: 149 mM) • Low calcium: 0.023 mM (Perilymph 0.6 -1.3 mM) • High electric Potential: 85 mV (CSF: 0mV) • Endocochlear potential • Low flow rate Wangemann, P. and Schacht, J. (1996) Cochlear homeostasis. In: P. Dallos, A.N. Popper and R.R. Fay (Eds) The Cochlea. Handbook of Auditory Research. Vol. 8, Springer, pp. 130-185.

  7. MR vs. CT

  8. 1. Widened • Pre-formed • Becoming symptomatic lately

  9. 1. Widened Duct * "funnel"-shape of the extraosseus portion of the endolymphatic sac

  10. 2. Enlarging

  11. 2. Enlarging • Changes in size and/or delineation of the endolymphatic duct • Clue: Sclerosis of surrounding bone • Fuzzy, hypoattenuated border

  12. 3. Third Window • Superior Semicircular Canal Dehiscience • Fenestration or thinned bony layer of the superior semicircular canal1 • Vestibular symptoms evoked by • Sound • Pressure applied to the external auditory canal • Frequency (path., n=1000)2 • Complete defect (fenestration) 0.5 % • 4/5 superior petrosal sinus • Thinned < 0.1 mm: 1,4 % LB Minor, D Salomon, JS Zinreich, DS Zee: Sound- and/or Pressure-Induced Vertigo Due to Bone Dehiscience of The Superior Semicircular Canal. Arch Otolaryngol 1998(124):249-258 2. JP Carey, LB Minor, GT Nager: Dehiscience or Thinning of Bone Overlying Superior Semicircular Canal in a Temporal Bone Survey. Arch Otolaryngol 2000(126): 137-147

  13. SSCD

  14. SSCD (?) • Superior petrosal sinus groove • Partial volume effect Superior Petrosal Sinus Groove

  15. 4.High Jugular Bulb Variants • Irregular shape

  16. Jugular Bulb Diverticulum • High flow in the jugular bulb may cause excavation (wall shear stress -> remodelling) • Sometimes it reaches structures of the inner ear • Posterior semicircular canal • Endolymphatic sac Posterior SCC Endolymphatic sac

  17. High Riding Jugular Bulb • Fuzzy margins, not to be explained by partial volume effects • Sclerosis Endolymphatic sac (intraosseus segment) Normal Margin

  18. Symptoms of Jugular Bulb Anomalies • Sensorineural hearing loss • Conductive hearing loss • Tinnitus • Pulsatile • Often not well differentiated by the Otologist • E.g. „progressieve sensoneural hearing loss with a conductive component“

  19. Hints • Think of it • In the field of SNHL, CT can provide more answers than MRI • Size (ax.) of the intraosseus part • Arbitrary: <= 1,5 mm, <= size f posterior SCC • Deliniation • Fuzziness • Environmental sclerotic reaction • Jugular bulb • High? High riding? • Divertikel? (coronal plane) • Arrosion of the inner ear?

  20. Conclusion • LVAS is a syndrome with enlargement being just one feature • In adults it may have different imaging features than in children e.g. • Enlargement of the endolymphatic sac • May be progressive • Surrounding sclerotic reaction • Dehiscience of a semicircular canal • Clinical correlation w. evoked vestibular symptoms essential • Jugular bulb variants • Jugular Bulb Diverticulum • High riding Jugular Bulb • Understanding of physiology is reconsidered. As is pathophysiology.

More Related