Basilar artery aneurysm with autonomic features: an interesting pathophysiological problem.

Abstract

Unruptured cerebral aneurysms often present with neuro-ophthalmological symptoms but ocular autonomic involvement from an aneurysm of the posterior circulation has not previously been reported. A patient is described with a basilar artery aneurysm presenting with headache and unilateral autonomic symptoms. After angiographic coiling of the aneurysm there was a near complete resolution of these features. The relevant anatomy and proposed mechanism of autonomic involvement of what may be considered--from a pathophysiological perspective as a secondary trigeminal-autonomic cephalgia--is discussed

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SHORT REPORT
Basilar artery aneurysm with autonomic features:
an interesting pathophysiological problem
N J GiYn, P J Goadsby
Abstract
Unruptured cerebral aneurysms often
present withneuro-ophthalmological
symptoms but ocular autonomic involve-
ment from an aneurysm of the posterior
circulation has not previously been re-
ported. A patient is described with a basi-
lararteryaneurysm
headache and unilateral autonomic symp-
toms. After angiographic coiling of the
aneurysm there was a near complete reso-
lution of these features. The relevant
anatomy and proposed mechanism of
autonomic involvement of what may be
considered—froma
perspective as a secondary trigeminal-
autonomic cephalgia— is discussed
(J Neurol Neurosurg Psychiatry 2001;71:805–808)
presentingwith
pathophysiological
Keywords: trigeminal autonomic cephalgia; cluster
headache; trigeminovascular system
Although the most common presentation of a
cerebral aneurysm is with subarachnoid haem-
orrhage, unruptured cerebral aneurysms may
present with headache or other symptoms, in
particular neuro-ophthalmological
These usually large, symptomatic aneurysms
are important to detect as, unlike small (<10
mm) aneurysms,which have an annual rupture
rate of 0.05%, those with a diameter greater
than 25 mm have an annual rupture rate of
6%.1 2The neuro-ophthalmological features
depend on the size and location of the
aneurysm relative to the visual pathways and
other cranial nerves.3However, autonomic fea-
tures from a basilar artery aneurysm have not
previously been described and have some
interesting physiological implications for the
trigeminal-autonomic syndromes.
features.
Case report
A 61 year old woman presented with a 30
month history of a left sided headache. The
headache started suddenly, was localised above
the left eye and radiated occipitally, occurring
for 3 to 14 days each month but with a residual
background pain. For the year before presenta-
tion the pain had become daily, associated with
left nasal stuYness, tearing and reddening of
the eye, and drooping of the eyelid. She had
noticed blurring of vision in the left eye for 4
months. Compound analgesics, ergotamine
with caVeine, and 50 mg amitriptyline at night
had not relieved the pain.
She had a medical history of hypertension
controlled on enalapril. Her mother had had
headaches but the patient had no personal his-
tory of headaches. On examination there was a
left sided ptosis, conjunctival injection, and
lacrimation (fig 1). Direct and consensual
pupillary responses to light and the accommo-
dation reflex were normal. Pupillography was
not performed. External ocular movements
were normal with no diplopia.Fundoscopy was
normal. She had no other neurological signs
apart from a mild, long standing “no-no” head
tremor. Her blood pressure was 120/80. Brain
CT without contrast showed a large basilar
artery aneurysm (fig 2) the location of which
was confirmed on CT angiography as lying
between the left superior cerebellar artery and
the left posterior cerebral artery (fig 3). The
aneurysm was successfully occluded with
angiographic coil embolisation. By day 5 after
embolisation the lacrimation, nasal stuYness,
and conjunctival injection had resolved, the
Figure 1
ptosis (with permission).
Patient before embolisation showing left sided
J Neurol Neurosurg Psychiatry 2001;71:805–808 805
Headache Group,
Institute of Neurology,
Queen Square, London
WC1N 3BG, UK
N J GiYn
P J Goadsby
Correspondence to:
Professor P J Goadsby
peterg@ion.ucl.ac.uk
Received 14 November 2000
and in final form
18 June 2001
Accepted 6 August 2001
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blurred vision and headache improved but pto-
sis persisted. Three months after embolisation
she had only infrequent mild daily headache
and the ptosis was less than on initial presenta-
tion. A repeat angiogram showed some com-
paction of the coils but an increase in the size of
the neck compared with the previous angio-
gram. It is planned to repeat the angiogram at
intervals in the future.
Discussion
We describe a patient who presented with
headache in association with cranial autonomic
symptoms manifested clinically by nasal stuY-
ness, lacrimation and conjunctival injection
(parasympathetic activation), and ptosis (sym-
pathetic inactivation).We consider these symp-
toms to be secondary to the basilar artery
aneurysm because there are anatomical path-
ways that would explain these features, and
symptoms improved after coiling of the aneu-
rysm.
This combination of autonomic features,
which may also include rhinorrhoea, forehead
and
oedema, are prominent in some primary head-
ache disorders,4the pain of which is mediated
via the trigeminovascular system. These disor-
ders include cluster headache, paroxysmal
hemicrania and SUNCT (short lasting neural-
giform headache with conjunctival injection
and tearing) syndrome, which may be collec-
tively described as trigeminal autonomic ce-
phalgias.5A lesser degree of parasympathetic
activation is not uncommonly seen in migraine
and may be accompanied by cranial release of
vasoactive intestinal polypeptide (VIP).6How-
ever, autonomic activation from structures
supplied by C1/C2 has only rarely been
described in humans and presents an interest-
ing pathophysiological challenge in terms of
explaining the mechanisms at work in this
patient’s clinical presentation.
The sensory innervation of the pain produc-
ing intracranial vascular structures of the fore-
brain is by trigeminal nerve aVerents whereas
those below the tentorium cerebelli are inner-
vated mainly by branches of the C2 dorsal
root.7Trigeminal nerve aVerents relay via the
trigeminal nucleus caudalis in the caudal
medulla and in neurons of the dorsal horns at
C1 and C2,8the trigeminocervical complex.
EVerents from the trigeminocervical complex
synapse in the superior salivatory nucleus.
Stimulation of these pain producing structures
in experimental animals leads to c-fos expres-
sion, activation of neurons, in the superior sali-
vatory nucleus.9Parasympathetic fibres pass
from the superior salivatory nucleus via the
greater petrosal nerve component of the facial
nerve to the sphenopalatine ganglion10 11to
mediate the parasympathetic features associ-
ated with trigeminally mediated pain. EVerent
nitric oxide and VIP containing fibres from the
sphenopalatine ganglion also produce vasodila-
tation of both cerebral and extracerebral arter-
ies, including the meningeal arteries that are
served by trigeminal aVerents. These connec-
tions complete a positive feedback loop for the
exacerbation of vasodilatation and pain in pri-
mary headache disorders—the trigeminovas-
cular reflex.12In addition, parasympathetic
mediated vasodilatation of the internal carotid
artery may injure the surrounding plexus of
sympathetic fibres en route to the eye and fore-
head. Thus trigeminal activation can cause
simultaneous parasympathetic activation and
sympathetic inactivation, probably accounting
for the autonomic features seen in the trigemi-
nal autonomic cephalgias.
How might cervical inputs entrain cranial
parasympathetic neurons? Indeed, there have
been previous reports of structures with a cer-
vical innervation—for instance, lesions pro-
duced from the lateral medullary syndrome, to
trigger headache syndromes with cranial auto-
nomic symptoms
headache.13–15This can be explained by conver-
gence of aVerent trigeminal and C2 aVerents at
the level of the trigeminocervical complex. In
experimental animals stimulation of structures
innervated by the trigeminal nerve, such as the
superior sagittal sinus8and middle meningeal
facialsweating,meiosis, and eyelid
similar tocluster
Figure 2
of the basilar artery.
CT without contrast showing the large aneurysm
Figure 3
aneurysm lying between superior cerebellar artery and
posterior cerebral artery.
Pre-embolisation CT angiogram showing
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GiYn,Goadsby
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artery,16activates neurons in the trigeminocer-
vical complex. Similarly, stimulation of the
greater occipital nerve,a branch of C2,leads to
activation of neurons in the very same re-
gions.17It has also been shown that stimulation
of the greater occipital nerve in rats leads to
ipsilateral conjunctival injection, tearing, and
ptosis in one third of animals.18Thus an
anatomical pathway exists whereby C2 activa-
tion may trigger eVerent neurons from the
trigeminocervical complex, including those to
the superior salivatory nucleus that mediate
parasympathetic activity.
Neuro-ophthalmological symptoms from in-
tracranial aneurysms are many and varied,
depending on anatomical site and size and
include visual loss, diplopia from III or VI
nerve palsies, Horner’s syndrome, and symp-
toms from midbrain or pontine involvement.
Visual loss may be caused by compressive
injury to the optic nerve or chiasm from aneu-
rysms of the anterior communicating, or the
supraclinoid carotid artery. Diplopia is most
commonly caused by a third nerve palsy from a
posterior communicating artery aneurysm, but
can also be caused by third nerve compression
from cavernous,carotid,or basilar artery aneu-
rysms or, more rarely, by sixth nerve compres-
sion of a vertebral artery aneurysm. Although
we report sympathetic inactivation from a basi-
lar aneurysm, Horner’s syndrome is usually
caused by aneurysms of the carotid cavernous
artery compressing the sympathetic nerve on
its course through the cavernous sinus. Rarely,
giant basilar bifurcation aneurysms or large
mid-basilar aneurysms may compress the mid-
brainand pons
ophthalmological signs including sixth nerve
palsies, horizontal gaze paresis, skew deviation,
internuclear ophthalmoplegia, lid retraction,
and nystagmus typically in association with
long tract brain stem signs such as hemiparesis
or alterations in consciousness. Symptoms may
also accrue from thrombus in a midbasilar
aneurysm obstructing flow resulting in local
pontine ischaemia. Thromboembolic disease
may also result in widespread posterior circula-
tion ischaemia,the top of the basilar syndrome,
causing abnormalities of convergence and ver-
tical gaze, skew deviation, visual field defects,
visual hallucinations, amnesia, and delirium.3
The patient we describe had both head pain
and features of parasympathetic activation and
sympathetic impairment that we consider to be
secondary to the aneurysm. We consider that
her ptosis was secondary to sympathetic
dysfunction rather than from third nerve com-
pression because of the lack of diplopia and
pupillary dilatation that would be typical of
third nerve palsy.She did not show meiosis that
would be typical of sympathetic dysfunction
but this would be in keeping with primary
trigeminal autonomic cephalgias that do not
always have a full house of local autonomic
features: lacrimation is the commonest feature
reported in cluster headache (80%) followed
by conjunctival injection (64%) with meiosis
being apparent in less than 10%.19However,we
cannot rule out the possibility that there may
have been subtle pupillary changes that may be
causingneuro-
missed without pharmacological pupillary test-
ing. It is diYcult to know the exact cause of her
blurring of vision, but it is likely to be due to a
combination of lacrimation and subclinical
pupillary change. The aneurysm was adjacent
to the midbrain but we do not attribute her
neuro-ophthalmological symptoms to com-
pression of the brain stem or ischaemia because
she did not have involvement of other cranial
nerves or long tracts that would be expected to
be aVected in a midbrain lesion. Similarly,
ischaemic changes were not apparent on the
patient’s MRI. We also consider that her head-
ache was secondary to the aneurysm. Although
the basilar artery only has sensory innervation
from C2, the head pain that she described
occurred in the distribution of the first division
of the ipsilateral trigeminal nerve (supraor-
bital) as well as that supplied by C2 (occipital),
again emphasising the cross talk between the
trigeminal and cervical sensory systems in the
trigeminocervical complex.
Basilar artery aneurysms represent only
3%-5% of all intracranial aneurysms but are
the most common aneurysms in the posterior
fossa. Treatment of basilar aneurysms by
angiographic embolisation with electrolytically
detachable coils achieves a high success rate in
suitable patients.20However, periodic angio-
graphic follow up after coil embolisation is rec-
ommended to identify aneurysm recurrence
and those patients with a high risk of late
rebleeding.21
The patient reported here had a basilar
artery aneurysm causing headache combined
with symptoms indicating autonomic dysfunc-
tion, features usually associated with stimula-
tion of trigeminally innervated structures. This
may be considered a secondary trigeminal
autonomic cephalgia. Basilar aneurysms have
not previously been reported to be associated
with such features, but neuronal connections
exist within the caudal brain stem that could
mediate such an eVect. We cannot pretend to
know, given the probably ubiquitous nature of
the trigeminal-autonomic connections, why
this particular lesion caused their activation
when similar lesions do not necessarily cause
this clinical picture.The patient’s presentation,
however, provides a useful human confirma-
tion of experimental animal studies that
illustrate the physiology of the trigeminal-
autonomic reflex.
The work reported has been supported by the Migraine Trust
and the Wellcome Trust. NJG is supported by GlaxoSmithK-
line. PJG is a Wellcome Trust senior research fellow.
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