Peduncular hallucinations after SAH

359

Peduncular hallucinations following subarachnoid haemorrhage

S. B. O'NEILL^ B. PENTLAND' & R. SELLAR^
^Department of Rehabilitation Medicine, Royal Victoria Hospital, Belfast, Northem Ireland, and Charles Bell Pavilion, Astley
Ainslie Hospital, and ^Department of Neuroradiology, Westem General Hospital, Edinburgh, Scotland, UK
Abstract
We describe the case of a 56-year-old wotnan who suffered vivid visual hallucination following subarachnoid haemorrhage
(SAH). These occurred from day 9 to day 28 after the haemorrhage. An association with sleep disturbance, clinical findings,
and the nature ofthe hallucinations suggested peduncular hallucinosis. Putative mechanisms in this case are discussed.
Key words: Aneurysm, peduncular hallucinosis, subarachnoid haemorrhage.
Introduction
We repon a case of peduncular hallucinosis, with
associated sleep disturbance associated with subarachnoid haemorrhage from a posterior communicating
artery aneurysm. Most reported cases of this syndrome
are described as resulting from infarct in the midbrain,
but magnetic resonance imaging (MRI) did not reveal
such a lesion in this case and putative mechanisms are
discussed.
Case report
A 56-year-oId, previously healthy woman presented
with sudden onset headache, photophobia, vomiting, confusion and neck stif&iess, and computed
tomography (CT) indicated subarachnoid haemorrhage (Fig. 2) in the prepontine area. The
following day angiography showed a right posterior
communicating artery aneurysm, which was treated
by endovascular coiling and a 21 -day course of
nimodipine was given. She remained confused,
with poor concentration, and impaired verbal and
non-verbal memory on psychological testing. She
was noted to be agitated and emotionally labile. A
left superior quadrantopia was the only focal
neurological sign.
On the ninth day after admission she reported vivid
visual hallucinations. Some involved children, including her own grandchild, wrapped in cellophane
floating around the ceiling and 'fluffy hats' in various
bright colours, either on their own or adorning
images of familiar people floating in the air. In
addition, she described the distressing vision of her
grandson crying for help and passing through the
wall of her hospital room. On one occasion, after a
home visit when she had travelled past some trees,
she saw the same trees inside her home, in the

kitchen and behind the front door. Associated with
these complaints, her sleep was markedly disturbed;
she was awake most of the night and would dress in
the early hours of the moming.
On the 28th day after admission, and 19 days after
the onset of hallucinations, olanzapine 2.5 mg was
given and within hours of the initial dose the
hallucinations ceased. They did not recur after
withdrawal of the medication 11 days later. By that
time cognitive testing revealed a retum to estimated premorbid function. The upper quadrantopia
persisted.
MRI some 20 weeks after the admission/coiling
procedure revealed a large aneurysm next to the
cerebral peduncle on the right, but no evidence of
either brain stem or cerebral infarct.

Discussion
Visual hallucinations accompanied by abnormal
sleep patterns or insomnia arising from lesions of
the midbrain have been described as peduncular
since early descriptions by Lhermitte & Van
Bogaert. The syndrome has been described elsewhere in association with infarcts," ~' with
compression of the midbrain^ and following SAH,
where it has been proposed that vasospasm is a
possible mechanism.*" ^ Peduncular hallucinosis has
been described as the only localizing sign of ruptured
upper posterior cerebral circulation.^
In this case, the vivid, often distressing hallucinations, accompanied by very disrupted sleep
patterns is in keeping with peduncular hallucinosis.
In addition, the patient described palinopsia with
the images of trees recurring indoors. The presence
of an upper quadrantopia is also indicative of a
disturbance in the posterior cerebral circulation.

Correspondence: Dr S, B. O'Neill, I-evel 3 OPC, Department of Rehabilitation Medicine, Royal Victoria Hospital, Grosvenor Road, Belfast BT12 6BA,
Nonhem Ireland. Tel: 44 28 90632038, Fax: 44 28 90633522. E-maii: soneilir" doctors.org.uk
Received for publication 12 January' 2005. Accepted 22 June 2005.
DOI: 10,1080/02688690500305407

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.S. B. O'Neill et al.
(Fig. 1). The right anterior choroidal artery origin was
demonstrated adjacent to this. The anterior choroidal
artery has been shown to supply the cerebral peduncles
and occlusion of it to produce homonymous superior
quadrantanopia.''
The mechanism producing the neurological symptoms, in this case, may have been one of vasospasm
and subsequent reduced cerebral perfusion, although
a more localized effect of pressure on the midbrain
due to tension in the interpeduncular cistern could
also give rise to the symptom pattern described. An
alternative mechanism, other than cerebral peduncle
infarct at or soon after endovascular coiling is
direct pressure from the aneurysm on the anterior
choroidal artery.
Authors' contributions

FIG. 1. Ncuroangiogram demonstrating a right posterior
communicating artery aneurysm adjacent to the origin of the
right anterior choroidal artery.

S. O'Neill, B. Pentland (BP) and R. Sellar collected
data regarding this patient (who received rehabilitation under the care of BP) and relevant investigations,
and were involved in drafting and revising the paper
for submission. Written consent to submit for
publication was obtained from the patient and was
forwarded to Miss Hatlcy (Editorial Assistant) in
January of this year.
There were no conflicting interests.
References

FiCr, 2. CT scan of brain, with contrast, showing the distribution of
the subarachnoid hlood.

However, MRI did not show infarcts in either the
brain stem or the cerebrum. MRI has demonstrated lesions described in other case reports.^'^"^
Howlett et al.^'^ described a case where CT of the
head was normal, but MRI using a double-echo
technique to acquire proton density and T2-weighted
images showed an area of increased signal density in
the left cerebral peduncle.
In this case conventional neuroangiography revealed
a right posterior communicating artery aneurysm

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