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products, the lesion enhances avidly and may con-
tain flow voids.
Meningiomas may diffusely infiltrate the skull base
extending into themiddleear and skull base foramina.
There may be a ‘‘permeative sclerotic’’ appearance
to the bone on CT and there is usually diffuse ‘‘en
plaque’’ intracranial enhancement (
Fig. 8
).
Vascular metastases in and around the jugular
foramen, from breast, lung, and thyroid primary
sites, are a recognized cause of PT. Metastases
from the thyroid may contain flow voids mimicking
a glomus tumour.
18
Haemangiopericytoma is a rare vascular tumour
associated with PT. Its avid enhancement character-
istics are similar to meningioma and these tumours
may be indistinguishable on imaging.
19
Other rare neoplastic causes of PT include
ossifying haemangiomas of the facial nerve and
cavernous haemangiomas.
11
Arteriovenous fistulae and malformations
Dural arteriovenous fistulae (dAVFs) account for
only 10
e
15% of all intracranial arteriovenous
malformations (AVMs) but they are a much more
frequent cause of PT than cerebral or neck AVMs.
They are usually acquired and may result from
recanalized venous sinus thrombosis. Dural AVFs
involving the transverse or sigmoid sinus are most
frequently implicated in PT (
Fig. 9
).
20
Direct AVFs between the ICA and the cavernous
sinus (carotico-cavernous fistulae) may also cause
PT, although pulsatile exophthalmos is a more
common presentation. Extracranial AVFs, which
usually involve branches of the vertebral artery
(but may involve the internal or external carotid
arteries), may rarely cause PT.
21
These abnormalities may be detected on
CTA/V or post-gadolinium MRI/MRA studies.
Findings may be subtle, particularly with in-
direct dAVFs. Shin et al.
22
retrospectively re-
viewed 54 patients with PT who were
evaluated for transverse sinus dural AVFs. CT
Figure 7
Transverse CT image of a 68-year-old patient
with facial nerve paralysis, sensorineural hearing loss,
and PT. There is aggressive bony destruction of the pos-
terior left petrous ridge (at the level of the vestibular
aqueduct) containing spiculated calcification. The ap-
pearance and location are characteristic of an endolym-
phatic sac tumour, sporadic in this case, which was
confirmed histologically.
Figure 8
Post-gadolinium, T1-weighted, coronal im-
age demonstrates enhancing meningioma in the inferior
left cerebellopontine angle cistern with enhancement
extending into the IAM. There is further extension of
the meningioma to fill the left middle ear cavity (other
images demonstrated this tissue to be continuous with
that in the jugular foramen).
Figure 9
Lateral projection of an occipital artery an-
giogram in a patient with a palpable thrill which was
transmitted to the frame of the bed. There is rapid an-
terograde drainage of the fistula into the sigmoid sinus.
When there is retrograde dural sinus flow and cortical
venous drainage, treatment is mandatory to prevent ve-
nous hypertension, intracranial haemorrhage, and focal
neurological deficits.
G. Madani, S.E.J. Connor
74