Australas Radio1 1993; 37: 90-92

A thrombosed saccular posterior cerebral artery aneurysm in an infant
H. CHEUNG AND F.C. LEE
Subang Jaya Medical Centre, Selangor, Malaysia

ABSTRACT
A case of recurrent hemiplegia
due to saccular aneurysm of the lefi
posterior cerebral artery in a female
infant is described. The diagnosis
was made at angiography, prompted
by CT detection of a hyperdense,
intra-aneurysmal thrombus, and
was confirmed a t subsequent
surgery.
CASE HISTORY
A 12 month old Chinese baby girl
was brought to the Pediatric Clinic at
the Subang Jaya Medical Centre in
May 1989 with a history of 3 episodes
of right-sided hemiplegia in the preceding 4 months. Each episode lasted
from 15 minutes to an hour, and was
sudden in onset, with the child unable
to move the right limbs. There was no
history of fever, ear discharge, seizure
or loss of consciousness. Her developmental milestones were normal.
On physical examination she was
able to move all four limbs normally.
There was no focal neurological
defect, and plantar reflexes were normal. Reflexes were normal and equal,
and there was no sensory deficit. The
fundi were also normal. Apart from
mild anaemia, with a haemoglobin of
10.2 g/dl (Normal = 13 - 18), the
haematological and metabolic profiles
were unremarkable.
The child was initially managed as
a case of epilepsy. The EEG, however,
did not show any epileptic focus.
Cranial CT, without contrast, showed
the presence of a small, solitary, focal
hyperdensity in the region of the left

Address for correspondence:
H. Cheung
Department of Diagnostic Radiology & Organ
Imaging
Chinese University of Hong Kong
Prince of Wales Hosuital
New Temtories
Hong Kong
Telephone: 636 2268
Fax: 636 0012

90

FIGURE 1 - Axial noncontrast CT showing a focal hyperdensity in the region of the Left Ambient
Cistern with attenuation value of 50 HU (arrow), at the site of the aneurysm.

ambient cistern (Figure 1). This measured 10 by 8 mm and was interpreted
as a focus of calcification, either within a granuloma or a vessel. A cerebral
angiogram was performed in view of
the CT finding and clinical suspicion
of a vascular aetiology. Selective left
carotid and vertebral studies were
done under general anaesthesia, and
the latter showed the presence of a
solitary left posterior cerebral artery
(PCA) aneurysm, arising distal to the
origin of the posterior choroidal artery.
There was also reduced filling of the
left PCA compared to the right side,
which may have been due to the
spasm (Figures 2A and B).
The parents were advised regarding
the inherent risk of aneurysmal rupture
and agreed to surgery. At surgery, a
left temporo-occipital craniotomy was
perfomed and a cruciate dural incision
made. Under magnification from a
Carl Zeiss OPMI 6 operating microscope, the left temporal lobe was elevated to expose the left PCA. A small
saccular aneurysm was found arising
from a branch of the PCA projecting
infero-medially into the ambient cistern. This was completely obliterated
at its neck by a curved Yasargil

Phynox 6 mm aneurysm clip, and the
sac excised.
On gross appearance the aneurysm
was a 1.2 cms spheroidal, berry-like
sac, with a smooth outer surface.
Section showed an intra-aneurysmal
thrombus with areas of early organisation. There was haemorrhage into its
wall, which was composed mainly of
fibrous tissue. Elastic tissue and
smooth muscle could not be identified
on light microscopy, and there was no
evidence of malignancy.
Post-operatively the child made an
uneventful recovery. Up to the time of
writing, clinical follow-up revealed no
recurrence of the right limb weakness.
Repeat angiography, performed 2
years later in June 1991, confirmed
total obliteration of the aneurysm neck
and normal left PCA circulation
(Figures 3A and B).

Submitted for publication on: 26th November.
1991
Accepted for publication on: 4th June, 1992

Australasian Radiology, Vol. 37, No. 1 , February. 1993

THROMBOSED SACCULAR POSTERIOR CEREBRAL ARTERY ANEURYSM
18%, compared to 2.5% in adults (3).
This includes mass effect, and neural
compression syndromes which are
commonly seen with giant aneurysms
in the posterior circulation (5). The
mode of presentation in our patient
was both peculiar and interesting. We
could not find recurrent episodic hemiplegia described previously with childhood aneurysms. However, this history
alerted us to the possibility of a vascular pathology. The recurrent motor
deficit may be related to intermittent
vascular insufficiency, perhaps due to
spasm or microembolism.

FIGURE 2 - Left vertebral angiogram showing the saccular aneurysm (arrows) in the frontal (a) and
lateral (b) projection. There is reduced flow seen in the left PCA compared to the right side.

DISCUSSION
Approximately 2% of all intracranial aneurysms Occur in
( I ) , and less than one hWdred cases
of arterial aneurysms have been
reported in children, younger than 5
years (2, 3). In children, these
saccular aneurysms appear distinct
from those in adults, on the basis of
sex predominance, size, location, aetiology and surgical outcome.

Diagnoses have mostly been
confirmed by angiography or surgery.
CT detects bleeding in the presence of
rupture, and may also show the
aneurysm, especially if large (8). The
presence of aneurysmal wall calcification and intra-aneurysmal thrombus
will also facilitate CT detection (1, 5).
In our patient the aneurysm was shown
as a focal hyperdensity in the region of
the left ambient cistern on non-contrast
CT. This may have been due to
either the thrombus in its lumen, or the
haemorrhage within its wall, both of
which were present on histological
examination of the excised aneurysm
sac.

The clinical presentation is most
Surgical results are generally better
commonly related to subarachnoid
bleeding, which is Seen in 65 - 80% than in adults and this was the case in
cases (4, 5 ) . However a non-haemor- this patient. Good recovery is reported
rhagic presentation occurs in about in 63 - 87% (1,3,4,6,9). An operative

There is a male predominance of
70% (1, 4). Approximately 25 - 45%
are giant aneurysms measuring more
than 2.5 cms in size ( 1 , 3, 5). A more
peripheral site is common (2, 3, 6),
which makes them relatively more
accessible at surgery. There is a
higher incidence i n the anterior
circulation ( 4 , 6). PCA saccular
aneurysms i n children less than
5 years are extremely uncommon,
being found in only 2 out of 32
patients in one review (2).

In children, the pathogenesis of
intracranial aneurysms includes trauma and infection (6, 7). A congenital
aetiology is suspected in those occuring in early childhood (2), or found in
association with other cerebral and
vascular congenital malformations
(3). The unproven hypothesis is that
they result from enlargement of
‘nubbins’Of
circulation (2).

FIGURE 3 - A follow-up left vertebral angiogram performed 2 years after surgery showing normal
Left PCA circulation in frontal (a) and lateral (b) projections. The aneurysm clip is arrowed.

Ausrrulusiun Radiologv. Vol. 37. No. 1 , February, 1993

91

H. CHEUNG AND F.C. LEE
mortality rate of 5% is attainable ( 5 ,
6). This is thought to be due to cerebral plasticity and a low incidence and
greater tolerance of spasm (4), with
perhaps better adaptation to ischaemia.
Prognosis, however, is considerably
worsened by the presence of massive
intracerebral haematoma, when there
is a high risk of mortality (9).

Amacher AL, Drake CG. Ferguson CG.
Posterior circulation aneurysms in young
people. Neuiosurgery 1981; 8: 315-320.
6. Pasqualin A. Mazza C, Cavazzani P,
Scienza R. DaPian R. Intracranial
aneurysms and subarachnoid haemorrhage
in children and adolescents. Childs Nervous
System 198q; 2 (4): 185-190.
7. Buckingham MJ, Crone KR, Ball WS,
Tomsick TA, Berger TS, Tew JM Jr.
Traumatic intracranial aneurysms in childhood. Neurosurgery 1988; 22 (2): 398-408.
8. TerBrugge K, Lee SH, Rao KCGV.
Cerebral vascular anomalies. In Cranial
Computed Tomography, eds Lee SH. Rao
KCGV, 1983; 549-550. McGraw-Hill.
5.

REFERENCES
1. Meyer FB, Sundt TM Jr. Fode NC, Morgan

MK, Forbes GS,Mellinger JF. Cerebral
aneurysms in childhood and adolescence.
Journal of Neurosurgery, 1989; 70 (3):

420-425.

Becker DH, Silverberg GD. Nelson DH,
Hanberg JW.Saccular aneurysm of infancy
and early childhood. Neurosurgery 1978; 2
(I): 1-7.
Ferrante L, Fortuna A, Celli P, Santoro A,
Fraioli B. Intracranial arterial aneurysms in
early childhood. Surgical Neurology 1988;
29 (1): 39-56.

Roche JL, Choux M, Czomy A, Dhellemes
P, Fast M, Frerebeau P et al. Intracranial
arterial aneurysm in children. A cooperative
study. Apropos of 43 cases. Neurochirurgie,
1988; 34 (4): 243-251.

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Australasian Radiology, Vol. 37, No. I, February, 1993