82 Headache Medicine, v.2, n.3, p.82-88, Jul./Aug./Sep. 2011

Functional anatomy of headache: circle of Willis

aneurysms, third cranial nerve and pain

Anatomia functional da cefaleia: aneurismas do polígono de Willis,

III nervo craniano e dor

ABSTRACTABSTRACT

ABSTRACT

Patients with intracranial aneurysm located at the internal carotid

artery-posterior communicating artery (ICA-PComA) often

present pain on the orbit or fronto-temporal region ipsilateral

to the aneurysm, as a warning sign a few days before rupture.

Given the close proximity between ICA-PComA aneurysm and

the oculomotor nerve, palsy of this cranial nerve may occur

during aneurysmal expansion (or rupture), resulting in

progressive eyelid ptosis, dilatation of the pupil and double

vision. In addition, aneurysm expansion may cause

compression not only of the oculomotor nerve, but of other

skull base pain-sensitive structures (e.g. dura-mater and

vessels), and pain ipsilateral to the aneurysm formation is

predictable. We reviewed the functional anatomy of circle of

Willis, oculomotor nerve and its topographical relationships

in order to better understand the pathophysiology linked to

pain and third-nerve palsy caused by an expanding ICA-

PComA aneurysm. Silicone-injected, formalin fixed cadaveric

heads were dissected to present the microsurgical anatomy of

the oculomotor nerve and its topographical relationships. In

addition, the relationship between the right ICA-PComA

aneurysm and the right third-nerve is also shown using

intraoperative images, obtained during surgical

microdissection and clipping of an unruptured aneurysm. We

also discuss about when and how to investigate patients with

headache associated with an isolated third-nerve palsy.

eywords:eywords:

eywords: Aneurysm; Headache; Oculomotor nerve; Pain;

Posterior communicating antery; Internal carotid artery,

Anatomy.

FUNCTIONAL ANATOMY OF HEADACHEFUNCTIONAL ANATOMY OF HEADACHE

FUNCTIONAL ANATOMY OF HEADACHE

Marcelo Moraes Valença

, Luciana P. A. Andrade-Valença

, Carolina Martins

Neurology and Neurosurgery Unit, Federal University of Pernambuco, Recife, Brazil and

Hospital Esperança, Recife, PE, Brazil

Medical School of Pernambuco IMIP, Recife, PE, Brazil

Valença MM, Andrade-Valença LPA, Martins C. Functional anatomy of headache: circle of Willis aneurysms,

third cranial nerve and pain. Headache Medicine. 2011;2(3):82-88

RESUMORESUMO

RESUMO

Pacientes com aneurisma intracraniano localizado na artéria

carótida interna na origem da artéria comunicante posterior

(ACI-AComP) frequentemente apresentam dor na órbita ou

na região fronto-temporal no mesmo lado do aneurisma, como

sinal de alarme poucos dias antes da ruptura. Devido à

proximidade do aneurisma da ACI-AComP do nervo craniano

oculomotor, paralisia desse nervo pode ocorrer durante

expansão aneurismática (ou ruptura), resultando em dilatação

pupilar, visão dupla e ptose palpebral progressiva. Além

disso, expansão aneurismática pode causar compressão não

só do terceiro nervo craniano, mas também de outras

estruturas da base do crânio sensíveis à dor (e.g. dura-mater

e vasos), e dor homolateral ao aneurisma é previsível. Nós

revisamos a anatomia funcional do polígono de Willis, nervo

oculomotor e suas relações topográficas para melhor entender

a fisiopatogenia relacionada a dor e paralisia do nervo oculo-

motor causada pela expansão do aneurisma da ACI-AComP.

Cabeças cadavéricas fixadas em formalina e injetadas com

silicone foram dissecadas para apresentar a anatomia

microcirúrgica do nervo oculomotor e sua relação topográfica.

Também a relação entre o aneurisma da ACI-AComP e o

terceiro nervo craniano é mostrada usando-se imagens

intraoperativas, obtidas durante dissecção microcirúrgica e

colocação de clipe em um aneurisma não roto. Nós também

discutimos sobre quando e como investigar pacientes com

cefaléia associada com uma paralisia isolada do terceiro nervo

craniano.

alavrasalavras

alavras

chaves:chaves:

chaves: Aneurisma; Cefaleia; Nervo oculomotor;

Dor; Artéria carótida interna; Artéria comunicante posterior;

Anatomia.

Headache Medicine, v.2, n.3, p.82-88, Jul./Aug./Sep. 2011 83

INTRODUCTION

Patients with intracranial aneurysm located at the

internal carotid artery-posterior communicating artery (ICA-

PComA) often present pain on the orbit or fronto-temporal

region ipsilateral to the aneurysm, as a warning sign a

few days before rupture.

1,2

Given the close proximity

between ICA-PComA aneurysm and the third cranial nerve

(oculomotor nerve), palsy of this cranial nerve may occur

during aneurysmal expansion (or rupture), resulting in

progressive eyelid ptosis, dilatation of the pupil and double

vision. In addition, aneurysm expansion may cause

compression not only of the oculomotor nerve, but of other

skull base pain-sensitive structures (e.g. dura-mater and

vessels), and pain ipsilateral to the aneurysm formation is

predictable (see Figures 1 and 2).

Thus, prompt evaluation of patients presenting recent

third-nerve palsy is of vital importance with the aim of

revealing an occult intracranial aneurysm, since most

people are unaware of its presence, because of the lack

of symptoms. In this regard, pain may even occur in the

absence of a third-nerve palsy. In fact, most of the

symptomatic ICA-PComA aneurysms are identified without

any oculomotor or pupillary deficits.

CLASSIFICATION OF THIRD-NERVE PALSIES

There are two main causes of oculomotor nerve palsy:

(1) vasculopathic (commonly associated with diabetes

mellitus and severe atherosclerosis) and (2) compressive

(associated with ICA-PComA aneurysms).

Frequently, both

forms of oculomotor palsy develop in an association with

headache (e.g. retro-orbital pain). In practice, it is not an

easy task to definitively distinguish one from the other

exclusively on clinical grounds.

Unlike patients with ICA-

PComA aneurysm, pain associated with vasculopathic

lesions subsides after several days and spontaneous

resolution of the third-nerve palsy is expected within 90

days.

Pupillary involvement is usually linked to

parasympathetic fibers compressed by the aneurysm as

the latter are located on the periphery (along the

dorsomedial surface) of the third cranial nerve.

As a general rule (around 80% of the cases),

the

pupil is spared in vasculopathic third-nerve palsy. However,

it was reported that 14% (7/51 patients) of the ICA-PComA

aneurysms are also associated with a pupillary-sparing

partial third-nerve palsy.

Furthermore, patients presenting

a pupil-sparing partial third-nerve palsy and harboring

an unruptured intracranial aneurysm (UIA) may develop

pupil dilation over time, as the compression progress.

5,6

Thus, we should assume that an aneurysm is the probable

cause of a third-nerve lesion when there is even a slight

degree of pupillary abnormality (the 'rule of the pupil'

applied to isolated third-nerve palsies),

and immediate

angiography is mandatory. Usually third-nerve dysfunction

is associated with an aneurysm 9-11 mm in size, but

smaller-sized aneurysms (5-6 mm) may also cause third-

nerve palsy.

7,8

Aneurysms of the ICA-PComA are the most

common aneurysm encountered in females.

And

thunderclap headache in association with third-nerve palsy

is characteristically found after subarachnoid hemorrhage

due to ICA-PComA aneurysm rupture. The estimated

frequency of third-nerve palsy in patients with ICA-PComA

aneurysm is 30% to 40%.

Aneurysms of the internal carotid artery are very

common (30-40% of the aneurysms in most series),

including aneurysms of the ophthalmic artery, superior

hypophyseal artery, posterior communicating artery,

anterior choroidal artery and carotid artery bifurcation.

Unruptured ophthalmic artery aneurysm habitually is

discovered during investigation of a recent side-looked

unilateral headache without any cranial nerve deficit.

WHEN AND HOW TO INVESTIGATE THE PATIENT

WITH HEADACHE AND THIRD-NERVE PALSY

Patients with pupil-sparing third-nerve palsies should

be initially evaluated with angio-MR or angio-CT

in order

to disclose an unexpected aneurysm, especially the elderly,

diabetic and those with arterial hypertension. Mathew and

colleagues

reported that an intracranial aneurysm was

the cause of isolated third-nerve palsy in 27/137 (19.7%)

patients. All 27 aneurysms were detected by angio-CT

and in no case was another lesion found by conventional

cerebral angiography. They concluded that "multidetector

computed tomographic angiography is a safe and

effective diagnostic imaging tool in detecting clinically

significant aneurysms when a patient presents with an acute

isolated third nerve palsy".

However, if after 12 weeks of

follow-up, no improvement in symptoms is observed,

digital angiography is necessary, even in case of previously

"normal" angio-MR or angio-CT. This is so because small

aneurysms may undetected under those methods.

Although, in the series of Mathew and colleagues,

only

81 of 110 (74%) of the individuals without an intracranial

aneurysm made a complete spontaneous recovery. On

the other hand, when the pupil is involved, a digital carotid

and vertebro-basilar angiography is compulsory, since

FUNCTIONAL ANATOMY OF HEADACHE: CIRCLE OF WILLIS ANEURYSMS, THIRD CRANIAL NERVE AND PAIN

84 Headache Medicine, v.2, n.3, p.82-88, Jul./Aug./Sep. 2011

VALENÇA MM, ANDRADE-VALENÇA LPA, MARTINS C

Figure 1. Silicone-injected cadaveric specimens have been dissected

to demonstrate the microsurgical anatomy of the oculomotor nerve

and its topographical relationships. A. A cut through the midbrain has

been performed, allowing a view along the skull base and circle of

Willis. The hypophyseal gland has been kept into the sellae, by cutting

through the pituitary stalk. The optic nerve has been cut prior to the

chiasm, as part of the right posterior cerebral artery. The posterior

communicating artery is seen linking the internal carotid artery to the

posterior cerebral artery. Although potent, this posterior

communicating artery is not fetal - a term reserved for the posterior

communicating artery which is the main supplier of the posterior

cerebral artery and associated with an atretic segment linking this

vessel to the basilar artery (P1). The oculomotor nerve emerges from

midbrain along the lateral limits of the posterior perforated substance,

starting its cisternal segment, on each side. The cisternal segment of

the oculomotor nerve passes between the

posterior cerebral and the superior cerebelar

arteries, in a course intimately related to the

posterior communicating artery and its

branches. B. The cisternal segment of the

oculomotor nerve ends at the cavernous sinus.

Here - under the carotid and the origin of the

posterior communicating artery (A) - the nerve

pierces the dura along the cavernous sinus roof,

passing through the oculomotor porus. The dura

along the roof of the cavernous sinus is divided

into two triangular areas: the posterior,

oculomotor triangle (green dotted area) and

the anterior, clinoidal part (blue dotted area).

The oculomotor porus is located on the posterior

part of the cavernous sinus roof. C. The dura

over the anterior clinoid has been removed and

the oculomotor porus opened to expose the

course of the oculomotor nerve along the roof

of the cavernous sinus. In this path along the

roof, the oculomotor nerve brings with it an

arachnoidal covering that forms a small

compartment: the oculomotor cistern.

Differently from the cisternal segment, the part

of the nerve coursing along the roof is

considerably fixed, being susceptible thus to

external compression. D. The right sylvian fissure has been opened in

another specimen, to simulate the surgical view into this area. The

carotid cistern is the expansion of the subarachnoidal space that extends

from the anterior clinoid process (removed) to the carotid bifurcation,

just above the cavernous sinus roof and Liliequist's membrane. It contains

the supraclinoid carotid artery, the origins of the ophthalmic, posterior

communicating, choroidal, middle cerebral and anterior cerebral

arteries. The oculomotor nerve pierces the roof of the cavernous sinus

in close relation to the carotid artery and the origin of the posterior

communicating artery. A.: Artery, ACA: Anterior Cerebral Artery, Ant.:

Anterior, Car.: Carotid, Cav.: Cavernous, Clin.: Clinoid, CN: Cranial

Nerve, Com.: Communicating, Int.: Internal, MCA: Middle Cerebral

Artery, PCA: Posterior Cerebral Artery, Oculom. Oculomotor, Pit.:

Pituitary, Post.: Posterior, Proc.: Process, SCA: Superior Cerebellar

Artery.

Headache Medicine, v.2, n.3, p.82-88, Jul./Aug./Sep. 2011 85

Figure 2. Intraoperative images. A. Lateral

view into the right carotid cistern. The internal

carotid artery is seen, just medial to the dura

covering the anterior clinoid process. Extensive

fibrotic tissue involves the aneurysmatic sac

and roof of the cavernous sinus (this patient

underwent a previous aneurysm operation 6

years before). B. The aneurysmal neck has been

exposed by careful microsurgical dissection.

The oculomotor nerve, entering into the

cavernous sinus, is now seen. C. The aneurysm

has been secured, preserving the posterior

communicating artery. D. Shrinkage of the

aneurism dome allows view into the posterior

part of the cavernous sinus roof. The oculomotor

nerve can be followed from its cisternal

segment up to the oculomotor porus. A.: Artery,

Ant.: Anterior, Car.: Carotid, Cav.: Cavernous,

Clin.: Clinoid, CN: Cranial Nerve, Com.:

Communicating, Int.: Internal, Post.: Posterior,

Proc.: Process.

chances of an aneurysm being present are higher. Yet,

the most sensitive tool for detection of intracranial

aneurysms is digital subtraction angiography. Although it

is an invasive study – with low risk of permanent neurologic

deficit (<0.1%)

– it should be used in order to avoid

missing small aneurysms.

HEADACHE AND UNRUPTURED INTRACRANIAL

ANEURYSMS

During the lifespan of the individual, an intracranial

aneurysm may develop in up to 10% of the population.

Nowadays, as a result of the widespread use of

neuroimaging techniques, it is not uncommon to become

aware of the existence of an UIA during an investigation of

a patient with headache. Nonetheless, the literature

addressing the relationship between headache and the so-

called 'incidental' UIA is scarce. The vast majority of vascular

neurosurgeons would consider the finding of an UIA as an

incidental event in a patient with headache.

In a recent

study, Choxi and colleagues

reported that a remarkable

improvement of the previous headache is expected after

surgical or endovascular treatment of an UIA.

We have previously reported

that the stabbing

headache formerly regarded as benign (characterized by

a sharp pain of short duration on the surface of the head)

might be a warning sign of intracranial, potentially

dangerous abnormalities, such as UIA, vascular

malformations or tumors (pituitary adenoma, meningioma,

acoustic schwannoma). Some of the characteristics of these

FUNCTIONAL ANATOMY OF HEADACHE: CIRCLE OF WILLIS ANEURYSMS, THIRD CRANIAL NERVE AND PAIN

86 Headache Medicine, v.2, n.3, p.82-88, Jul./Aug./Sep. 2011

Figure 3. Magnetic resonance angiography (MRA). Right side, profile:

Internal carotid artery aneurysm, related to the origin of a right, fetal

pattern, posterior communicating artery. A.: Artery, ACA: Anterior

Cerebral Artery, Car.: Carotid, Com.: Communicating, Int.: Internal,

MCA: Middle Cerebral Artery, Post.: Posterior.

VALENÇA MM, ANDRADE-VALENÇA LPA, MARTINS C

secondary stabbing headache attacks (referred by us as

'alarm bell headache') are the following: (a) a gradual

increase in pain severity with an increased frequency over

the previous few months or years (crescent pattern); (b) a

dura-mater contact with the lesion; (c) repeatedly confined

to one or just a few points on the head; (d) unilateral on

the same side as the lesion; (e) precipitated by head

movements or the Valsalva maneuver.

In 2007 we reported

that ICA-PComA aneurysms

may cause cluster headache-like symptoms and surgical

clipping of the aneurysms resolved the cluster pain,

suggesting a relationship between peripheral lesions

located in the parasellar/sellar region and the appearance

of cluster headache symptoms.

In addition, headache during the preoperative period

in a patient with a known UIA is also to be expected as

the result of a recent cerebral angiography performed in

a patient with an UIA (6.5.5 [G44.810] Angiography

headache, ICHD-II).

It is estimated that half of the patients

submitted to angiography experienced headache within

24 hours.

15,16

On the other hand, both headache attributed

to intracranial endovascular procedures (6.5.4 [G44.810],

ICHD-II)

14,17

and post-craniotomy headache (5.7 [G44.88],

ICHD-II)

14,18,19

may occur postoperatively.

CLASSIFICATION OF UNRUPTURED

INTRACRANIAL ANEURYSMS BASED ON THE

FORM OF DIAGNOSIS

An UIA may be diagnosed in a number of different

conditions such as (1) incidentally; (2) associated with a

ruptured aneurysm in a patient with multiple aneurysms

(as expected in 15-35% of cases, mainly in females); or

during investigation of (3) family members with familial

aneurysms, (4) patients with a mass-effect due to a large

or giant aneurysm (i.e. cranial nerve palsy or brainstem

compression), and (5) patients with symptomatic headache

simulating a primary type of headache (e.g. migraine,

tension-type headache, stabbing headache, cluster

headache or other trigemino-autonomic headaches).

12,13,20

'RED FLAGS' SIGNALING UNRUPTURED

INTRACRANIAL ANEURYSMS

Headache may be interpreted as a 'red flag'

signaling that an UIA may be its cause, mainly when at

least one of the following is present: (1) it is of recent

onset, (2) side-looked unilateral pain with no side shift,

(3) gradual increase in severity, (4) patient's age >50,

(5) precipitated by Valsalva maneuvers or head

movements.

Some authors also recommend

neuroimaging evaluation of patients with trigemino-

autonomic headaches, such as cluster headache.

13,21

Thus, studies evaluating headache associated with UIA

are of great importance to allow for early diagnosis

before catastrophic rupture occurs.

MICROSURGICAL ANATOMY OF THE CIRCLE

OF WILLIS AND OCULOMOTOR NERVE

The location of an aneurysm in the circle of Willis is

closely related to the specific anatomical arterial

configuration. There is a relationship between the lack of

visualization of a unilateral A1 segment and detection of

anterior communicating artery (AComA) aneurysms,

whereas ICA-PComA aneurysms are related to the fetal

type of posterior cerebral artery.

In this regard, an

illustrative, case (36-year-old woman) is presented (Figure

3). The MR-angiography clearly shows the internal carotid

artery aneurysm, related to the origin of a right, fetal

pattern, posterior cerebral artery.

We recently analyzed a consecutive series of 158

patients with cerebral aneurysms originating in one of the

three following locations: IC-PComA, AComA, and middle

cerebral artery (MCA).23 The frequency of fetal-PCA was

significantly higher in the group of patients with IC-PComA

aneurysms (24% vs. 2% AComA and 3% MCA

aneurysms).

Headache Medicine, v.2, n.3, p.82-88, Jul./Aug./Sep. 2011 87

Silicone-injected, formalin fixed cadaveric heads

were dissected to present the microsurgical anatomy of

the oculomotor nerve and its topographical relationships

(Figure 1). The relationship between the right internal

carotid artery aneurysm at the origin of the posterior

communicating artery and the right third-nerve is also

shown in a 42-year-old woman with an unruptured

aneurysm. Intraoperative images, obtained during

surgical dissection, through a Zeiss Opmi Pentero

Surgery Microscope camera, display the adhesions

between the lesion and the entire roof of the cavernous

sinus.

In this area, where the supraclinoidal internal carotid

artery is situated, three main nerve systems are encountered:

(i) the sympathetic nervous system, (ii) the parasympathetic

nervous system, and (iii) the trigeminal nervous system.

The sympathetic nerves, which innervate orbital structures,

originate from the superior cervical ganglia and take an

upward direction, by the side of the internal carotid artery

to reach the parasellar region via the internal carotid nerve,

which divides into two branches: the lateral branch, which

distributes to the internal carotid artery (internal carotid

plexus), and the medial branches, which also distributes

filaments to the internal carotid artery and, continuing

onward, forms the cavernous plexus. Trigeminal nerve fibers

are diffusely distributed all over the parasellar structures,

together with vessels and dura-mater.

As the internal carotid

artery is surrounded by trigeminal and sympathetic fibers,

aneurysm formation with gradual saccular growth may

stretch and stimulate the nerve endings and this may cause

pain in the periorbital and/or temporal regions. Aneurysmal

compression of pain sensory afferent fibers of the

ophthalmic division of the trigeminal nerve present around

the oculomotor nerve and into parasellar dura is seen by

some as cause of orbital pain.

In conclusion, we reviewed the functional anatomy

of circle of Willis, oculomotor nerve and its topographical

relationships in order to better understand the

pathophysiology linked to pain and third-nerve palsy

caused by an expanding ICA-PComA aneurysm.

REFERENCES

1. Kasner SE, Liu GT, Galetta SL. Neuro-ophthalmologic aspects of

aneurysms. Neuroimaging Clin N Am. 1997;7(4):679-92.

2. Valença MM, Valença LPAA. Hemorragia subaracnóide: causas,

manifestações e tratamento. Neurobiol. 2000; 63:97-104

3. Dimopoulos VG, Fountas KN, Feltes CH, Robinson JS, Grigorian

AA. Literature review regarding the methodology of assessing

third nerve paresis associated with non-ruptured posterior

communicating artery aneurysms. Neurosurg Rev. 2005;

28(4):256-60.

4. Laskowitz DT, Galetta SL, Raps EC Neuro-ophthalmologic

emergencies. In: Neurologic and neurosurgical emergencies.

Ed. Cruz J, 1st edition, W. B. Saunders Company, Philadelphia,

p. 155-185

5. Kissel JT, Burde RM, Klingele TG, Zeiger HE. Pupil-sparing

oculomotor palsies with internal carotid-posterior communicating

artery aneurysms. Ann Neurol. 1983;13(2): 149-54.

6. Saito R, Sugawara T, Mikawa S, Fukuda T, Kohama M, Seki H.

Pupil-sparing oculomotor nerve paresis as an early symptom of

unruptured internal carotid-posterior communicating artery

aneurysms: three case reports. Neurol Med Chir (Tokyo). 2008;

48(7):304-6.

7. Keane JR, Ahmadi J. Third-nerve palsies and angiography. Arch

Neurol. 1991;48(5):470.

8. Mathew MR, Teasdale E, McFadzean RM. Multidetector computed

tomographic angiography in isolated third nerve palsy.

Ophthalmology. 2008;115(8):1411-5. Epub 2008 Feb 15.

9. Wong GK, Boet R, Poon WS, Yu S, Lam JM. A review of isolated

third nerve palsy without subarachnoid hemorrhage using

computed tomographic angiography as the first line of

investigation. Clin Neurol Neurosurg. 2004;107(1):27-31.

10. Cloft HJ, Joseph GJ, Dion JE. Risk of cerebral angiography in

patients with subarachnoid hemorrhage, cerebral aneurysm, and

arteriovenous malformation: a meta-analysis. Stroke1999;

30:317-20.

11. Choxi AA, Durrani AK, Mericle RA. Both Surgical Clipping and

Endovascular Embolization of Unruptured Intracranial Aneurysms

Are Associated With Long-term Improvement in Self-Reported

Quantitative Headache Scores. Neurosurgery. 2011;69(1):

128-34.

12. Valenca MM, Andrade-Valenca LPA, Oliveira DA, Silva LC,

Martins HAL and Medeiros FL. 'Alarm bell headache': a secondary

stabbing headache. Cephalalgia. 2009; 29 (Suppl. 1):157.

13. Valença MM, Andrade-Valença LP, Martins C, de Fátima Vasco

Aragão M, Batista LL, Peres MF, da Silva WF. Cluster headache

and intracranial aneurysm. J Headache Pain. 2007;8(5):277-82.

14. Classification and diagnostic criteria for headache disorders,

cranial neuralgia and facial pain. Second Edition. Cephalalgia

2004; Suppl 1:1-160.

15. Ramadan NM, Gilkey SJ, Mitchell M, Sawaya KL, Mitsias P.

Postangiography headache. Headache. 1995;35(1):21-4.

16. Gil-Gouveia RS, Sousa RF, Lopes L, Campos J, Martins IP. Post-

angiography headaches. J Headache Pain. 2008;9(5):327-30.

Epub 2008 Jul 31.

17. Evers S, Marziniak M. Headache attributed to carotid or vertebral

artery pain. Handb Clin Neurol. 2010;97:541-5.

18. Valença MM, Valença LPA, Carlotti Jr CG, Assirati JÁ, Leite JP,

Bordini CA, Speciali JG. Cefaléia pós-lobectomia temporal em

pacientes com epilepsia do lobo temporal mesial. Migrânea

Cefaléias. 2002;5:90

19. Rocha-Filho P, Gherpelli J, de Siqueira J, Rabello G. Post-

craniotomy headache: A proposed revision of IHS diagnostic

criteria. Cephalalgia. 2010 Feb 22. [Epub ahead of print]

FUNCTIONAL ANATOMY OF HEADACHE: CIRCLE OF WILLIS ANEURYSMS, THIRD CRANIAL NERVE AND PAIN

88 Headache Medicine, v.2, n.3, p.82-88, Jul./Aug./Sep. 2011

COMMENT

To study headaches with consistent unilateral presentations

(especially at the same side), in addition to study head pain

sufferers with isolated third-nerve palsies is crucial to determine

anatomo-pathological relationships between structural lesions

in the vicinity of the oculomotor nerve emerging branches as

well as its topographic relationship with the internal carotid

artery-posterior communicating artery (ICA-PCA).

In this review, the authors discuss not only the anatomical

perspective but also the clinical features. The pain frequently

reported as ipsilateral, representing a warning sign few days

before the rupture of aneurysms occurring in this internal carotid

artery branch is emphasized. Expatiating about oculomotor

palsies and the importance of excluding the aneurysms of the

internal carotid artery-posterior communicating artery, the

authors present the classification of the third-nerve palsies

and when and how to investigate the patients presenting it.

Discussion on whether an angiography is indicated and the

arterial territories in which they have to be performed, is

presented in this review, which also presents important data

on available reports from specialized literature.

Patients presenting unilateral headache around the eye

are common in daily neurological clinics, but the difficulties

in evaluating these subjects based on clinical findings only,

especially when a third-nerve palsy is also manifested and the

pain is atypical warrants the need for reviewing unusual

headache types. Since the authors present their own experience

and compare it with other author’s cases, discussion presented

herein is useful for clinicians willing to get update.

Special interest is devoted to the classification of

unruptured intracranial aneurysms based on the form of

diagnosis and to the “red flags” signaling unruptured

intracranial aneurysms such as its recent onset, age over 50

years, side-looked unilateral pain with, gradual increase in

severity and precipitation by Valsalva maneuvers or head

movements. Attention should be dedicated as well to the

complementary examinations mandatory to evaluate these

patients. It is a must-read review.

Abouch Valenty Krymchantowski, MD, PhD

Correspondence

Marcelo M. VMarcelo M. V

Marcelo M. V

alençaalença

alença

Neurology and Neurosurgery Unit, Department of

Neuropsychiatry, Federal University of Pernambuco

50670-420 – Recife, PE, Brazil

20. Valença MM, Guterman L. Both surgical clipping endovascular

embolization of unruptured intracranial aneurysm are

associated with long-term improvement in self-reported

quantitative headache scores COMMENTS. Neurosurgery.

2011;29:133-4

21. Favier I, van Vliet JA, Roon KI, Witteveen RJ, Verschuuren JJ,

Ferrari MD, Haan J. Trigeminal autonomic cephalgias due to

structural lesions: a review of 31 cases. Arch Neurol. 2007;

64(1):25-31.

22. Horikoshi T, Akiyama I, Yamagata Z, Sugita M, Nukui H. Magnetic

resonance angiographic evidence of sex-linked variations in the

circle of Willis and the occurrence of cerebral aneurysms. J

Neurosurg. 2002;96(4):697-703.

23. Silva Neto AR. Influence of carotid siphon geometry and circle

of Willis variants on the origen of carotid-posterior

communicanting aneurysms. MSc Dissertation, Federal

University of Pernambuco, Recife, Brazil, 2009, 41p. [Portuguese]

24. Martins C, Yasuda A, Campero A, Rhoton AL Jr. Microsurgical

anatomy of oculomotor cistern. Operative Neurosurgery. 2006;

58(4): 220-8.

25. Lanzino G, Andreoli A, Tognetti F, Limoni P, Calbucci F, Bortolami

R, et al. Orbital pain and unruptured carotid-posterior

communicating artery aneurysms: the role of sensory fibers of

the third cranial nerve. Acta Neurochir (Wien). 1993;120(1-

2):7-11.

26. Martins C, Costa e Silva IE, Campero A, Yasuda A, Aguiar

LR,Tatagiba M, et al. Microsurgical anatomy of the orbit: the rule

of seven. Anatomy Research International. Volume 2011 (2011),

Article ID 468727, 14 pages.

VALENÇA MM, ANDRADE-VALENÇA LPA, MARTINS C

Received: June 1, 2011

Accepted: June 8, 2011