“

True” Posterior

Communicating

Artery

Aneurysm

Report of Two Cases— — Akihiro

TAKAHASHI,

Hiroyasu

Michio Department

KAMIYAMA,

KITAGAWA

of Neurosurgery,

Hokkaido

and

Hiroyuki

Hiroshi

IMAMURA,

ABE

University School of Medicine,

Sapporo

Abstract Two cases of true posterior communicating artery (PcomA) aneurysm are described. A 27-year-old female with subarachnoid hemorrhage demonstrated a saccular aneurysm at the branch of the anterior choroidal artery from the PcomA. The aneurysm was successfully clipped. A 23-year-old male in volved in an automobile accident suffered from traumatic subarachnoid hemorrhage. Computed tomography 10 weeks after head injury demonstrated a high-density mass in the right parasellar region, diagnosed as a traumatic aneurysm arising from the PcomA. The aneurysm was successfully clipped. Histological examination demonstrated findings consistent with true aneurysm. Key words: anterior

cerebral

choroidal

aneurysm,

artery,

traumatic

subarachnoid

aneurysm,

posterior

communicating

artery,

hemorrhage

Introduction Aneurysms of the posterior communicating artery (PcomA) located distal to the junction of the internal carotid artery or proximal to that of the posterior cerebral artery (PCA) are true PcomA aneurysms. Such aneurysms are very rare, with a frequency of approximately 0-3.3% in large aneurysm se ries.3,s,7,"o,"4"5'21,22,24 Thirteen true PcomA aneurysms have been reported. 1,5,8,9,11,12,16,18-21,24) We describe two true PcomA aneurysms including the first reported traumatic type, and discuss the etiology. Fig. 1

Case

Reports

Case 1: A 27-year-old female experienced sudden onset of severe headache and was transferred to our hospital with suspected subarachnoid hemorrhage on February 3, 1987. On admission, she was drowsy and complained of headache. Neurological examina tion revealed no abnormal findings other than nuchal rigidity. Computed tomographic (CT) scans confirm ed subarachnoid hemorrhage. Angiograms disclosed an aneurysm located at the branch of the anterior Received 11, 1991

September

17, 1991;

Accepted

November

Case 1. Left carotid angiogram, showing an aneurysm (arrow) located at the branch of the anterior choroidal artery (arrowheads) from the PcomA.

choroidal artery from the PcomA (Fig. 1). The aneurysm was successfully clipped with a Ya~argil 692 clip. A well-developed PcomA was ob served (Fig. 2). The postoperative course was uneventful. Case 2: A 23-year-old male was involved in a traffic accident on July 10, 1990. On admission, he was drowsy or stuporous. CT scans revealed subarach noid hemorrhage in the right basal cistern. Repeat

Fig. 5

Case

2.

revealing Fig. 2

Case

1.

erative

Fig.

3

Schematic findings.

artery,

AN:

artery,

III:

Case

2.

AchA:

aneurysm,

the

anterior

section

organized

intraop

lumen

of the aneurysm

choroidal

ternal

hematoma.

internal

of

the

thrombus and

Masson

aneurysm, within

the absence stain,

the of ex

x 200.

carotid

nerve.

carotid

aneurysm

of

ICA:

oculomotor

Right

saccular

drawing

A cross

angiogram,

arising

from

showing the PcomA.

a

CT scans 2 weeks later showed infarction in the territory of the PCA. He regained consciousness 4 weeks later. CT scans on September 27, 1990 demonstrated a high-density mass in the parasellar region, diagnosed as a true PcomA aneurysm by angiography (Fig. 3). The aneurysm was located where the PcomA penetrated Liliquest's membrane. The aneurysm had a broad neck and adhered to the tentorial edge intraoperatively (Fig. 4). There were no perforating vessels branching from the periphery of the aneu rysm. And the oculomotor nerve was located under the aneurysm. The aneurysm was clipped with a Ya~argil 752 clip, and resected. Histological exami nation showed findings consistent with a true aneu rysm. An organized thrombus was present within the aneurysmal lumen, and hematoma was absent (Fig. 5). Discussion

Fig. 4

Case erative

2.

Schematic findings.

nal carotid

artery,

drawing

of

the

intraop

AN:

aneurysm,

ICA:

III:

oculomotor

nerve.

inter

Table 1 summarizes the 15 reported cases including ours of true PcomA aneurysm. 1,5,8.9,11,12,16,18-21,24) These include seven males and eight females, ranging from 23 to 73 years old. All demonstrated subarachnoid hemorrhage. Fourteen patients had a saccular aneurysm and one a fusiform aneurysm. The aneurysm was located at the infundibular dilata tion of the PcomA or distal to the internal carotid artery in nine cases (Cases 1, 2, 4, 6, 8-10, 12, 13), at the center of the PcomA in five (Cases 3, 7, 11, 14, 15), and proximal to the PCA in one (Case 5). Eleven saccular aneurysms were unrelated to ar terial branching. The PcomAs were normal or di lated 6) in all cases. All saccular aneurysms except one

Table

1

Summary

of reported

cases

of true

PcomA

aneurysm

were treated by clipping and the fusiform aneurysm by trapping. The postoperative course was favor able in 13 cases. Anterior choroidal artery originating from the PcomA occurs in only 0-6.7% of humans. 2,4,13," Only one aneurysm (Case 7) other than our Case 1 located where the anterior choroidal artery branches from the PcomA has been reported. These aneurysms may develop at the arterial bifurcation sec ondary to increased hemodynamic stress and a fragile arterial wall. Our Case 2 is considered to be a true and traumatic type. Possibly, the PcomA was damaged by rubbing against the tentorial edge or Liliquest's membrane, based on the subarachnoid hemorrhage and cerebral infarction in the PCA territory after head injury. A true aneurysm may be caused by disruption of the muscularis, intima, and internal elastica.23) However, many traumatic aneurysms are false aneurysms. Only one aneurysm with a broad neck located at the center of the PcomA unassociated with arterial branching has been reported (Case 3). However, it was not associated

with head trauma. In fact, no traumatic aneurysm of the PcomA has previously been described. True PcomA aneurysms can be clipped easily, causing no damage to the perforators from the PcomA, since most saccular aneurysms are un related to arterial branching.

References 1)

2)

3) 4)

5)

Abiko S, Orita T: A case of “true” posterior com municating artery aneurysm. No Shinkei Geka 9: 1181-1185, 1981 (in Japanese) Carpenter MB, Noback CR, Moss ML: The anterior choroidal artery: Its origin, course, distribution, and variations. Arch Neurol Psychiat 71: 714-722, 1954 Dandy WE: Intracranial Arterial Aneurysm. New York, Comstock Publishing, 1944, 58 pp Herman LH, Fernando OU, Gurdjian ES: The anterior choroidal artery: An anatomical study of its area of distribution. Anat Rec 154: 95-102, 1966 Kamiyama K, Sakurai Y, Suzuki J: Case report: Aneurysm of the posterior communicating artery itself. Report of a successful treated case. Neurol

6) 7)

8)

9)

10) 11)

12)

13) 14)

15)

16)

Med Chir (Tokyo) 20: 81-84, 1980 Krayenbühl H, Yasargil G: Cerebral Angiography, ed 2. Stuttgart, Georg Thieme Verlag, 1982, 75 pp Krayenbühl HA, Yasargil MG, Flamm ES, Tew JM: Microsurgical treatment of intracranial saccular aneurysms. J Neurosurg 37: 678-686, 1972 Kudo T: An operative complication in a patient with a true posterior communicating artery aneurysm: Case report and review of the literature. Neurosurgery 27: 650-653, 1990 Masuda T, Uno M, Matsumoto K: Relatively rare ruptured posterior communicating artery aneurysm. Geka 46: 1081-1083, 1984 (in Japanese) McDonald C, Dorb M: Intracranial aneurysm. Arch Neurol Psychiat 42: 298-328, 1938 Miyazawa T, Watanabe H, Hasegawa T, Ishimaru S, Ishii S: A case of posterior communicating artery aneurysm associated with vascular anomaly of circle of Willis. No Shinkei Geka 11: 541-546, 1983 (in Japanese) Okada T, Matsuda M: A case of “true” posterior communicating artery aneurysm. No Socchu 10: 270 274, 1988 (in Japanese) Otomo E: The anterior choroidal artery. Arch Neurol (Chicago) 13: 656-658, 1965 Poppen JL: Special treatment of intracranial aneurysms: Experiences with 143 surgically treated patients. J Neurosurg 8: 75-102, 1951 Sano K: An introduction of subarachnoid hemor rhage: Focus on treatment of ruptured cerebral aneurysms. Nippon Rinsho 36: 460-466, 1978 (in Japanese) Stuntz JT, Ojemann GA, Alvord EC: Radiographic and histologic demonstration of an aneurysm developing on the infundibulum of the posterior com municating artery. J Neurosurg 33: 591-595, 1970

17)

18)

19)

20)

21)

22)

23)

24)

Takahashi S, Suga T, Kawata Y, Sakamoto K: Anterior choroidal artery: Angiographic analysis of variations and anomalies. AJNR 11: 719-729, 1990 Takeda N, Tamaki N, Asada M, Kurata H, Matsumoto S: “True” posterior communicating ar tery aneurysm presenting the abducens nerve palsy. No Shinkei Geka 13: 1331-1334, 1985 (in Japanese) Tanizaki Y, Kobayashi S, Ichinose Y, Tsuji T, Sugita K: A case of “true” posterior communicating artery aneurysm with rare intraoperative misclipping. Shinshu Igaku Zasshi 30: 396-401, 1982 (in Japanese) Trasi S, Vincent LM, Zingesser LH: Development of aneurysm from infundibulum of posterior com municating artery with documentation of prior hemorrhage. AJNR 2: 368-370, 1981 Waga S, Kojima T, Tochio H, Morikawa A: Aneurysm of the posterior communicating artery itself. Neurol Med Chir (Tokyo) 24: 495-498, 1984 Yasargil MG, Smith RD: Management of aneurysms of anterior circulation by intracranial procedures, in Youmans JR (ed): Neurological Surgery, ed 2, vol 3. Philadelphia, Saunders, 1982, pp 1663-1696 Yonas H, Dujovny M: “True” traumatic aneurysm of the intracranial internal carotid artery: Case report. Neurosurgery 7: 499-502, 1980 Yoshida M, Watanabe M, Kuramoto S: “True” posterior communicating Neurol 11: 379-381, 1979

artery

aneurysm.

Address reprint requests to: A. Takahashi, M.D., ment of Neurosurgery, Hokkaido University of 060,

Medicine, Japan.

North-15,

West-7,

Kita-ku,

Surg

Depart School Sapporo