98 / 264
papilloedema, and visual disturbance.
9
In a series of
145 cases of PT, IIH was the most frequent diagnosis
accounting for 56 cases.
9
There is a high prevalence
of venous sinus stenoses (withmore than 90% of cases
having bilateral stenoses on MRV;
Fig. 13
).
31
Imaging
studies are aimed at excluding other causes of intra-
cranial hypertension (
Fig. 14
) but some associated
imaging features, such as an empty sella, flattening
of the posterior globes, and distension of the periop-
tic arachnoid spaces, have been described.
32
Diagno-
sis is made by measuring the opening pressure at
lumbar puncture.
Venous anomalies and variations
Venous variations and anomalies are frequently
associated with subjective PT. Some, such as
venous sinus dominance and a high-riding jugular
bulb (
Fig. 15
a) (which extends above the inferior
border of the round window, occurring in 25% of
the population), are far more prevalent than ve-
nous tinnitus. This implies that although they may
predispose to PT in some cases, the association is
frequently speculative. If identified, there should
be a continued search for other treatable causes
of PT. Other entities related to venous PT include
an aberrant anteromedially placed or laterally
placed sigmoid sinus (
Fig. 15
b), venous sinus steno-
ses, and large emissary or subcranial veins.
7,11,31
Non-vascular pulsatile tinnitus
Non-vascular causes of PT include muscular tinni-
tus (palatal and middle ear myoclonus) where
rhythmic contractions of the muscle around the
skull base result in objective PT. Such non-vascular
tinnitus may not be pulse-synchronous. Disease of
the middle ear and mastoid, such as cholesterol
granuloma (
Fig. 16
), patulous eustachian tubes,
and dehiscent semicircular canals, are also
documented causes.
6,33
Conclusion
PT has diverse causes. The aim of radiology is to
demonstrate treatable causes. Combined CTA/V
has the advantage of demonstrating middle ear,
skull base, and vascular diseases in a single exam-
ination, and is the ideal first-line radiological
studying in patients without an intra/retrotym-
panic mass. Small arteriovenous fistulae may be
occult on cross-sectional imaging and require
catheter angiography for diagnosis.
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Figure 16
T1-weighted, coronal MR image demon-
strates a hyperintense left mastoid cholesterol
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Imaging in pulsatile tinnitus
77