Clinical Medicine 2019 Vol 19, No 3: 257–8

IMAGE OF THE MONTH

Image of the month: A giant unruptured anterior
communicating artery aneurysm presenting with seizures
Authors: Dylan J Mac Lochlainn, A Vasileios SotiropoulosB and Breffni C KeeganC

Fig 1. Computed tomography showing a soft tissue mass with peripheral
calcifications.

Fig 2. T1-weighted magnetic resonance image showing the thrombosed
aneurysmal sac splaying the posterior optic nerves.

A 74-year-old man presented following a presumed first seizure.
His wife awoke to find him unresponsive, grunting and foaming at
the mouth. He was responding appropriately when the ambulance

crew attended. There was no associated limb jerking, incontinence
or tongue biting, and he denied chest pain or palpitations. A similar
episode four years earlier was reported, but he had never received a
formal diagnosis of epilepsy. Clinical examination was unremarkable.
Admission computed tomography (CT) revealed a homogeneous
soft tissue mass with calcifications superior to the pituitary fossa
(Fig 1). Blood tests, including adrenocorticotropic hormone,
insulin-like growth factor-1, thyroid stimulating hormone and short
synacthen test, were unremarkable. Visual field testing was normal.

Authors: Acore medical trainee, South West Acute Hospital,
Enniskillen, UK; Bconsultant radiologist, South West Acute Hospital,
Enniskillen, UK; Cconsultant stroke physician, South West Acute
Hospital, Enniskillen, UK
© Royal College of Physicians 2019. All rights reserved.

CMJv19n3-MacLochlainn.indd 257

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Image of the month

Fig 3. T2-weighted magnetic resonance image showing a hypointense
thrombosed aneurysmal sac.

Fig 4. Magnetic resonance angiogram showing blood flow within the
neck of the aneurysm.

Magnetic resonance (MR) imaging brain and MR angiography
demonstrated a large left anterior communicating artery (ACoA)
saccular aneurysm. The thrombosed aneurysmal sac displayed
high signal intensity on T1-weighted images with splaying of the
posterior optic nerves (Fig 2), and appeared hypointense on the
T2-weighted sequences (Fig 3). On 3D time-of-flight MR angiogram
(Fig 4), flow was identified within the neck of the aneurysm. There
was no evidence of associated bleeding or additional aneurysms,
and pituitary fossa was normal with no adenoma.
He underwent review by the regional neurosurgical team. No
operative intervention was advised, and interval imaging involving
CT angiography was recommended.
Several days later, he re-presented following a witnessed tonicclonic seizure. CT angiogram on this admission noted no interval
change. Antiepileptic medication was introduced at this point. At
outpatient review 1 month later, he reported no further seizures.
Giant intracranial aneurysms are defined as aneurysms
exceeding 25 mm in diameter and comprise approximately 5%
of all intracranial aneurysms. Unruptured intracranial aneurysms
are a rare but recognised cause of epilepsy. Reported cases have

predominantly been associated with middle cerebral artery
aneurysms, with only rare reports involving ACoA aneurysms.1
The management of giant intracranial aneurysms can be
problematic, and the optimal treatment has not been clearly
established. Surgical clipping is considered to be particularly high risk
for giant aneurysms, but a range of endovascular techniques exist
as potential alternatives where intervention is being considered.2
Overall, the prognosis for giant aneurysms is often poor.2 ■

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References
1 Patil A, Menon GR, Nair S. Unruptured anterior communicating artery
aneurysms presenting with seizure. Asian J Neurosurg 2013;8:164.
2 Lv X, Jiang C, Li Y et al. Treatment of giant intracranial aneurysms.
Interv Neuroradiology 2009;15:135–44.

Address for correspondence: Dr Breffni C Keegan, consultant
stroke physician, South West Acute Hospital, Enniskillen BT74
6DN, UK.
Email: breffni.keegan@westerntrust.hscni.net

© Royal College of Physicians 2019. All rights reserved.

4/30/19 10:11 PM