an almost understimated realm
Dr. Dieter Goettmann
Stuttgart
University Medical Centers Groningen, Nijmegen

LVAS is a syndrom

Sensorineural hearing loss
 Sudden
 Fluctuating
 Progressive

Imaging subsidary
E.Pernkopf: Atlas der topographischen Anatomie des Menschen, Bd.IV,München 1960, Tafel 162

Endolymphatic sac


Extraosseus part
Intraosseus part
 Commonly interpretated as the
endoymphatic duct


Preductal
Endolymphatic duct


Small & short
Alsmost never
dilatated
Intraosseus Part
External Aperture of
Vestibular Aqueduct
Extraosseus Part of
Endolymphatic Sac
Unique extracellular fluid
 High potassium: 157 mM (CSF: 3.1 mM)




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)


Paramagnetic
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.
MR
?
CT
+
-
Soft tissue
Spatial
resolution
Scan time
Endolymph,
Sac, Duct
Position jugular
bulb
-+
-
+
+
(Borders)
+


Pre-formed
Becoming symptomatic lately
Duct
* "funnel"-shape of the extraosseus portion of the endolymphatic sac
Sep. 2008
Sep. 2009


Changes in size and/or delineation of the
endolymphatic duct
Clue: Sclerosis of surrounding bone

Fuzzy, hypoattenuated border

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 %
1. 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


Superior petrosal sinus groove
Partial volume effect
Superior Petrosal Sinus
Groove

Irregular shape


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


Fuzzy margins, not to be explained by partial
volume effects
Endolymphatic sac
Sclerosis
(intraosseus segment)
Normal
Margin



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“



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?



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.