Original Article 249

Authors

B. Demirgil, Ö. Günaldı, B. Tugcu, L. Postalci, B. Colluoglu, O. Tanriverdi, M. Asilturk

Affiliation

Bakırköy Research and Training Hospital for Neurology, Neurosurgery and Phsychiatry, 2nd Neurosurgery Clinic, Istanbul,
Turkey

Key words
䉴 distal posterior inferior
䊉
cerebellar artery
䉴 aneurysm
䊉
䉴 multiple aneurysms
䊉

Abstract
&

Bibliography
DOI 10.1055/s-0028-1082302
Minim Invas Neurosurg 2008;
51: 249–252
© Georg Thieme Verlag KG
Stuttgart · New York
ISSN 0946-7211
Correspondence
Dr. Ö. Günaldı
Atakent mah
İkitelli cad
Ihlamurevleri B2 blok No:10
Halkalı/Küçükçekmece
Istanbul
Turkey
Tel.: + 90/212/543 86 67
gunaldi@mynet.com

Introduction: The distal segment of the PICA
(posterior inferior cerebellar artery) is a very rare
localization for the occurrence of intracranial
aneurysms. They are almost always presented
with SAH (subarachnoid hemorrhage). Hydrocephalus often develops following intraventricular hemorrhage (IVH). The distal PICA segment
is a quite difficult localization for neurosurgical
procedures. The authors could not find any case
report presenting multiple aneurysms on a distal
segment of PICA in the literature.
Case 1: A 62-year-old male patient was admitted to the emergency room with complaints of
sudden headache, vomiting and blackout of consciousness. Early CT scans demonstrated SAH
and intraventricular hemorrhage (IVH). In his
medical history, SAH had been determined in
our clinic 3 month previously. He had carried
out conservative treatment ever since the distal
located PICA aneurysm had been determined.
There was no determined symptom except for
moderate neck stiffness in his physical examination. In his neurological examination, he was stuporous and he localized the pain in his left arm. A
ventriculo-atrial shunt operation was performed
after the external ventricular drainage which
was applied at the acute period of hydrocephalus
in his previous SAH. Both of the left distal PICA
aneurysms were clipped via a left lateral suboc-

Introduction
&
The PICA is an uncommon localization for intracranial aneurysms and distal PICA aneurysms are
particularly rare. They almost always present
with SAH. Hydrocephalus often develops following intraventricular hemorrhage. The distal PICA
segment is a quite difficult localization for neurosurgical procedures. Because of the narrowing of

cipital craniotomy. The patient was discharged
from the hospital without neurological deficit
in the seventh day postoperatively. His control
examination was normal and there was not any
fixed pathological filling in the control cerebral
digital subtraction angiography (DSA).
Case 2: A 49-year-old female patient was admitted to the emergency service with the complaint of headache, dizziness and vomiting. She
was neurologically intact except for neck stiffness. A cranial CT demonstrated triventricular
hydrocephalus and a hemispheric cerebellar
hematoma, which was about 1 × 1.5 cm in diameter. The cerebellar DSA was normal. The patient
was discharged with no neurological impairment. In the examination of the control cerebral
DSA, two aneurysmatic fillings were determined
in the distal segments of right posterior inferior
cerebellar artery (PICA). Both of the aneurysms
were clipped through a microsurgical approach.
No neurological deficit was determined in the
postoperative early and late stages. In the control
cerebral DSA, no aneurysmatic filling was seen.
Discussion: Distal PICA aneurysms constitute
only 0.28–1.4 % of all intracranial aneurysms.
Most of the patients present with SAH and along
with this; intraventricular hemorrhage is seen
and later on, hydrocephalus develops. As for
treatment, surgery and endovascular interference methods can be applied.

the arterial diameter, endovascular procedures
are not suitable for aneurysms of this region.
False negative DSA results are another problem
from the point of diagnosis [1, 2].
The authors present two cases of multiple aneurysms localized on a single PICA distal segment.

Demirgil B et al. Multiple Aneurysms … Minim Invas Neurosurg 2008; 51: 249–252

Downloaded by: Universite Laval. Copyrighted material.

Multiple Aneurysms of the Distal Posterior Inferior
Cerebellar Artery: Two Case Reports

250 Original Article

Fig. 1 Cranial computed tomography
revealed subarachnoid
hemorrhage in the
posterior fossa.

Case Reports
&
Patient 1
History and examination
A 62-year-old male was admitted to the emergency room with
the complaints of sudden headache, vomiting and disturbance of
consciousness.

Treatment and post-treatment course
On neurological examination, he was stuporous. He had hemiplegia on the right side. A cranial CT examination demonstrated
posterior fossa SAH (䊉䉴 Fig. 1). A cerebral DSA examination
showed two small saccular aneurysms localized at the left distal
segment of the PICA (䊉䉴 Fig. 2). Because of developing hydrocephalus in his clinical and radiological follow-up, an external
ventricular drainage was inserted and the patient underwent a
surgical procedure for clipping both aneurysms via a left lateral
suboccipital craniotomy, following a ventriculoatrial shunt procedure. The patient was discharged from the hospital at postoperative seventh day. He was neurologically intact. Cerebral DSA
performed in the follow-up period, was unremarkable (䊉䉴 Fig. 3).

Patient 2
History and examination
The second patient, a 49-year-old female was admitted with
complaints of headache, dizziness and vomiting. She had no
neurological deficit but cranial CT demonstrated a triventricular
hydrocephalus and a 1 × 1.5 cm sized hemispheric cerebellar
Demirgil B et al. Multiple Aneurysms … Minim Invas Neurosurg 2008; 51: 249–252

Fig. 3 Control digital subtraction angiography demonstrated no
aneurysmatic fillings.

Fig. 4 Digital subtraction angiography after one month from the first
bleeding demonstrated two small aneurysmatic fillings located at the
right PICA distal segment.

hematoma related to the fourth ventricle. DSA analysis showed
no vascular abnormality so she was discharged from the hospital following a ventriculo-peritoneal shunt operation. She was
neurologically intact. A control DSA was performed 1 month
later. Two small aneurysmatic fillings located at right PICA distal
segment were seen in the DSA (䊉䉴 Fig. 4).

Treatment and post-treatment course
The aneurysms were clipped via a midline suboccipital craniotomy. She was discharged from hospital as neurologically intact
following a control DSA (䊉䉴 Fig. 5).

Discussion
&
The PICA may show a very high rate variations according to the
localizations that its origin takes. It usually originates from the
intradural vertebral artery (VA). However, a PICA originating
from the extradural VA may rarely be seen [3, 5–8]. Variations
that take an origin below the foramen magnum level are seen in
about 18 % of all cases [9]. The PICA consists of six anatomic segments, namely: anterior, lateral, posterior medullar segments,

Downloaded by: Universite Laval. Copyrighted material.

Fig. 2 Two small
saccular aneurysms
were demonstrated on
the digital subtraction
angiography.

Original Article 251

tonsillomedullar, telovelotonsillar and cortical segments [10].
Distal PICA aneurysms are particularly rare. It is reported that
their observation rate is about 0.28–1.4 % among all cerebral
aneurysms [1]. The VA-originated aneurysms appear in the PICA
in 80 % and usually in the VA-PICA division point. And this rate is
lower in the distal area. 15–30 % of all PICA aneurysms are seen
in the distal part and especially in the peripheral PICA segments
[2]. Although in some series, the distal segment PICA aneurysm
incidence is higher in the telovelotonsillar and tonsillomedullar
segments [1], it is reported that, in a 16-case-series which comprises 18 aneurysms, the incidence is higher in the anterior
medullar segment [11]. It is thought that hemodynamic stress
and congenital factors play role in the occurrence of distal PICA
aneurysms [12].
Most of the cases present with SAH [4]. Compared with other
intracranial aneurysms they have a higher incidence of IVH and
hydrocephalus. In ruptured PICA aneurysms, the re-bleeding
risk is about 78 % which is considerably high [13, 14]. In the cases
reported by Sadato, IVH is seen in 85 % of distal PICA aneurysm
hemorrhages. In Kallmes’s report [11], it is stated that in the 95 %
of the PICA aneurysms with IVH, hydrocephalus developed. 75 %
of these cases are graded as 4, according to the Fisher grading
scale. In the present study, two aneurysms in one distal PICA
segment were determined for each patient. SAH, IVH and accompanying hydrocephalus were determined. In the first case, a conservative approach was applied because of the patient having
refused the surgical approach, but one month later; he presented
with SAH along with intraventricular hemorrhage and in a short
time hydrocephalus developed. In the second case; SAH, IVH and
hydrocephalus were existing at the first admission of the patient
to our hospital. No aneurysm had been seen in the first cerebral
DSA but an aneurysm was seen in the control DSA examination.
AVM (arteriovenous malformations), dural fistula, hypoplastic
vertebral artery and cerebral aneurysms in further areas may
accompany distal PICA aneurysms [11]. In the present cases, no
additional pathology was found that accompanied the aneurysm. Microsurgical clipping or coil occlusion [4, 15–17] of the
main arteries which the aneurysm is located on, has been used
by many authors. Some others have combined the occlusion of
the main arteries with distal bypass procedures [16–19]. Nussbaum has emphasized the significance of the PICA-PICA or PICAOA anastomoses used in the dissection of the distal PICA. The
surgical treatment of PICA aneurysms is quite difficult [20, 21].
In PICA aneurysms, surgeons have to use surgical dissection corridors with deep, narrow trajectories that are intimately involved
with perforating brainstem arteries and cranial nerves [22–24].
However, in the diagnosis and the treatment of the disease, crucial improvements are recorded in the latest report of the past 5

years [11, 20, 25–27]. The literature contains rare reports of distal PICA aneurysms treated by an endovascular approach. The
distal PICA aneurysm location and vascular tortuosity may make
it impossible to superselectively catheterize the PICA for effective coil deployment. Furthermore, compared with endovascular treatment, open surgery may serve to remove subarachnoid
blood. In the present cases, the aneurysms were clipped successfully via a suboccipital craniotomy. Postoperatively, no neurosurgical deficit was seen in the early and late stages. In the
control DSA which was made 3 months later, no occlusion findings were observed in the distal part of the aneurysm and the
clipped segment.

Conclusion
&
Distal PICA aneurysms are extremely rare and comprise less
than 30 % of all PICA aneurysms [1, 2]. The authors found only
one case report presenting multiple aneurysms on a single PICA
distal segment [28]. Both of the patients we described were
symptomatically similar to a posterior fossa circulation SAH.
Because there is not enough experience reported in the literature, two alternative microsurgical approaches were performed
for the treatment, namely one lateral and one midline suboccipital craniotomy. The present report aims to add new knowledge to the literature about these very unique and rare types and
localizations of intracranial aneurysms.

References
1 Tamano Y, Kobayashi T, Hagiwara S et al. Aneurysm of the distal posterior
inferior cerebellar artery originating from the extracranial and extradural
vertebral artery. Neurol Med Chir (Tokyo) 2003; 43: 301–303
2 Ishikawa T, Suzuki A, Yasui N. Distal posterior inferior cerebellar aneurysms – report of 12 cases. Neurol Med Chir (Tokyo) 1990; 30: 100–108
3 Bertalanffy H, Seeger W. The dorsolateral, suboccipital, transcondylar
approach to the lower clivus and anterior portion of the craniocervical junction. Neurosurgery 1991; 19: 29
4 Liew D, Ng PY, Ng I. Surgical management of ruptured and unruptured
symptomatic posterior inferior cerebellar artery aneurysms. Br J Neurosurg 2004; 18: 608–612
5 Lister JR, Rhoton AL Jr, Matsushima T et al. Microsurgical anatomy of the
posterior inferior cerebellar artery. Neurosurgery 1982; 10: 170–199
6 Margolis MT, Newton TH. The posterior inferior cerebellar artery. In:
Newton TH, Potts DG, eds. Radiology of the Skull and Brain. St Louis:
Mosby 1974; Vol. 2 Bk 2: 1719–1775
7 Osborn AG. Introduction to cerebral angiography. Philadelphia: Harper
& Row 1980; 379–427
8 Sen CN, Sekhar LN. An extreme lateral approach to intradural lesions
of the cervical spine and foramen magnum. Neurosurgery 1990; 27:
197–204
9 Horiuchi T, Tanaka Y, Hongo K et al. Characteristics of distal posteroinferior cerebellar artery aneurysms. Neurosurgery 2003; 53: 589–
595; discussion 595–596
10 Lister JR, Rhoton AL Jr, Matsushima T et al. Microsurgical anatomy of the
posterior inferior cerebellar artery. Neurosurgery 1982; 10: 170–199
11 Orakcioglu B, Schuknecht B, Otani N et al. Distal posterior inferior cerebellar artery aneurysms: Clinical characteristics and surgical management. Acta Neurochir (Wien) 2005; 147: 1131–1139
12 Todaka T, Hamada J, Yano S et al. Successful clipping of a distal posterior inferior cerebellar artery aneurysm located on the anterior surface of the medulla oblongata – case report. Neurol Med Chir (Tokyo)
2002; 42: 158–161
13 Dinichert A, Rufenacht DA, Tribolet N. Dissecting aneurysms of the
posterior inferior cerebellar artery: report of four cases and review of
the literature. J Clin Neurosci 2000; 6: 515–520
14 Jamjoom A. Recurrent subarachnoid haemorrhage from an angiographically occult large distal pica aneurysm. Br J Neurosurg 1991; 5:
393–398
15 Ikeda A, Yamaguchi T, Yamaguchi T et al. Excision and end-to-end anastomosis of a fusiform aneurysm of the distal posterior inferior cerebel-

Demirgil B et al. Multiple Aneurysms … Minim Invas Neurosurg 2008; 51: 249–252

Downloaded by: Universite Laval. Copyrighted material.

Fig. 5 Control digital
subtraction angiography demonstrated no
aneurysmatic fillings.

252 Original Article
23 Tawk RG, Bendok BR, Qureshi AI et al. Isolated dissections and dissecting aneurysms of the posterior inferior cerebellar artery: topic and
literature review. Neurosurg Rev 2003; 26: 180–187
24 Yamamoto I, Tsugane R, Ohya M et al. Peripheral aneurysms of the posterior inferior cerebellar artery. Neurosurgery 1984; 15: 839–845
25 Tikkakoski T, Leinonen S, Siniluoto T et al. Isolated dissecting aneurysm
of the left posterior inferior cerebellar artery: endovascular treatment
with a Gugliemi detachable coil. AJNR Am J Neuroradiol 1997; 18:
936–938
26 Fujimura M, Nishijima M, Midorikawa H et al. Fatal rupture following
intra-aneurysmal embolization for the distal posterior inferior cerebellar artery aneurysm with parent artery preservation. Clin Neurol
Neurosurg 2003; 117–120
27 Dinichert A, Rufenacht DA, Tribolet N. Dissecting aneurysms of the
posterior inferior cerebellar artery: report of four cases and review of
the literature. J Clin Neurosci 2000; 7: 515–520
28 Beyerl BD, Heros RC. Multiple peripheral aneurysms of the posterior
inferior cerebellar artery. Neurosurgery 1986; 19: 285–289

Downloaded by: Universite Laval. Copyrighted material.

lar artery associated with ischemia – case report. Neurol Med Chir
(Tokyo) 1991; 31: 351–355
16 Nishino A, Sakurai Y, Satoh H et al. Aneurysms of the distal posterior
inferior cerebellar artery; the report of 10 cases. No Shinkei Geka
1991; 19: 925–932
17 Yamaura A, Isobe K, Nakamura T et al. Posterior inferior cerebellar
aneurysm in the fourth ventricle. Surg Neurol 1980; 13: 297–299
18 Hudgins RJ, Day AL, Quisling RG et al. Aneurysms of the posterior inferior cerebellar artery. A clinical and anatomical analysis. J Neurosurg
1983; 58: 381–387
19 Kaptain GJ, Lanzino G, Do HM et al. Posterior inferior cerebellar artery
aneurysms associated with posterior fossa arteriovenous malformation: report of five cases and literature review. Surg Neurol 1999; 51:
146–152
20 Mukonoweshuro W, Laitt RD, Hughes DG. Endovascular treatment of
PICA aneurysms. Neuroradiology 2003; 45: 188–192
21 Salcman M, Rigamonti D, Numaguchi Y et al. Aneurysms of the posterior inferior cerebellar artery-vertebral artery complex: variations on
a theme. Neurosurgery 1990; 27: 12–20; discussion 20–21
22 Nussbaum ES, Mendez A, Camarata P et al. Surgical management of
fusiform aneurysms of the peripheral posteroinferior cerebellar
artery. Neurosurgery 2003; 53: 831–834

Demirgil B et al. Multiple Aneurysms … Minim Invas Neurosurg 2008; 51: 249–252