Suprachiasmal

Carotid-ophthalmic

Artery

Aneurysm

Report of Two Cases— — Ahmed

DIRAZ,

Fukuo

NAKAGAWA,

Shigeaki

KOBAYASHI,

Tsutomu

Hiroshi

TSUJI

and

OKUDERA,

Yasuyuki

TOBA

Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Nagano

Abstract

Two rare suprachiasmal carotid-ophthalmic artery aneurysms, one large and one giant, were discovered incidentally. The patients had no visual disturbances. Angiography showed superomedial projection of the sac. The aneurysms were clipped via an ipsilateral pterional approach. A supra chiasmal carotid-ophthalmic artery aneurysm is indicated when preoperative angiography reveals a superomedial carotid-ophthalmic artery aneurysm without visual disturbances. Direct surgery to clipp a suprachiasmal aneurysm should be carried out to prevent rupture of these frequently large aneurysms. Key words:

carotid-ophthalmic

artery,

aneurysm,

Introduction Carotid-ophthalmic artery aneurysms, which arise from the internal carotid artery (ICA) between the origins of the ophthalmic and posterior com municating arteries, may project in various direc tions. 1,2,7,10) Many variations of carotid-ophthalmic artery aneurysm have been described based on the position of the aneurysm in relation to the ICA. 1,10,21) The rare suprachiasmal type of aneurysm passes up ward and medially toward the anterior com municating complex and rests upon the superior sur face of the optic nerve and chiasm.10) Only two of 46 cases of carotid-ophthalmic artery aneurysm en countered at our institution belonged to this category. Here, we discuss the diagnosis, surgical treatment, and nomenclature of this rare aneurysm. Case

suprachiasmal

type,

direct

surgery

tomographic (CT) scans revealed a calcified lesion in the left parasellar area (Fig. 1), which was markedly enhanced postcontrast. The diagnosis was a giant aneurysm in the left carotid-ophthalmic region based on angiograms (Fig. 2 left, center). Direct surgery was indicated to prevent rupture and development of visual disturbances. A left pte rional approach opened the Sylvian fissure, exposing the lateral wall of a large aneurysm. The medial surface of the aneurysm was carefully dissected from the frontal lobe. The dome was thick and calcified. The left optic nerve was deeper than the aneurysm

Reports

Case 1: A 60-year-old female visited our clinic for neurological examination after her 52-year-old brother died from a subarachnoid hemorrhage. She had experienced heavy headedness and occasional nausea and vomiting. No other neurological manifestations were detected. Precontrast computed Fig. Received

January

9, 1992;

Accepted

May

27,

1992

1

Case

1.

hyperdense

CT

scan,

lesion

showing

an aneurysm

in the left parasellar

as a region.

Fig. 2

Fig.

3

Case

Case 1. left, center: Preoperative anteroposterior (left) and lateral (center) left carotid angio grams, showing a giant suprachiasmal carotid-ophthalmic artery aneurysm. right: Postopera tive lateral left carotid angiogram, showing aneurysm clipping by two long Sugita clips.

1.

Schematic

drawing

the left clipping.

pterional approach for A: aneurysm, 1: ICA, 2:

field via aneurysm optic nerve, mic artery.

3: oculomotor

of the

nerve,

operative

4: ophthal

and the lateral side markedly compressed by the sac, although preoperative clinical perimetry had not revealed any visual field disturbance. The roof of the optic canal and the anterior clinoid process were drill ed away intradurally. This and opening the dura pro pria allowed mobilization and safe retraction of the optic nerve. The dural fibrous ring at the intra and extradural junction surrounding the ICA was cut cir cumferentially to free the carotid artery. Bleeding from the cavernous sinus was controlled by elevating her head and packing with Oxycel. The neck of the aneurysm was then accessible for dissection and clip ping. The ophthalmic artery branched from the ICA just proximal to the aneurysmal neck. A long Sugita clip with 30 mm straight blades was applied from the anterolateral to the posteromedial side of the neck. Special care was taken to avoid occlusion or stenosis of the parent and ophthalmic arteries. For this pur

pose, the aneurysmal dome was punctured to decrease the size and tension. However, the calcified dome failed to collapse. Fortunately, the clip blades remained on the neck, which was not calcified. The dome was still pulsating, so a second bayonet-type clip was placed on the neck just distal and parallel to the first (Figs. 2 right and 3). After aneurysm clip ping, Doppler ultrasonography was used to confirm adequate blood flow in the ICA and ophthalmic artery. The postoperative course was uneventful except for the occurrence of a nasal visual field defect in the left eye. Case 2: A 69-year-old male presented with a history of chronic headache. CT scans showed a hyperdense lesion in the proximal part of the Sylvian fissure (Fig. 4). Cerebral angiograms revealed a right carotid ophthalmic artery aneurysm measuring 2 x 1.5 cm (Fig. 5 left, center). He had no visual problems or history of subarachnoid hemorrhage. The aneurysm was clipped to prevent rupture via an ipsilateral pterional approach. The Sylvian fissure and carotid cistern were opened to expose

Fig. 4

Case

2.

hyperdense Sylvian

CT scan, lesion fissure.

showing in the

an aneurysm

proximal

part

as a of the

Fig. 5 Case 2. left, center: Preoperative anteroposterior (left) and lateral (center) right carotid angio grams, showing a large suprachiasmal carotid-ophthalmic artery aneurysm. right: Postopera tive anteroposterior right carotid angiogram, showing clipping of the aneurysm by three long Sugita clips.

Discussion

Fig. 6

Case field

2.

Schematic

via the right

drawing pterional

of the approach

ping of the aneurysm. A: aneurysm, 2: optic nerve, 3: oculomotor nerve.

operative for clip 1: ICA,

the aneurysm above the ICA with the optic nerve lying below. The surgical procedure was essentially as in Case 1, with unroofing of the optic canal, re moval of the anterior clinoid process, and cutting of the carotid dural ring. The ophthalmic artery was identified proximal to the aneurysmal neck. The clip ping procedure occluded the aneurysm, leaving just a small stony-hard portion of the neck. An 18 mm straight clip was placed to spare the optic nerve which ran deeper and medially. This clip did not com pletely occlude the aneurysm because the neck was highly sclerotic and the thickness was uneven. A sec ond, straight ring-type clip was placed parallel to the first. A third, reinforcing clip was placed on the dome side (Figs. 5 right and 6). The postoperative course was uneventful without neurosurgical complications.

Kothandaram et al.") classified carotid-ophthalmic artery aneurysms into three categories: subchiasmal, passing horizontally and medially at right angles to the parent carotid artery and compressing the under surface of the nerve; suprachiasmal, passing upward and medially toward the anterior communicating complex and resting upon the superior surface of the optic nerve and chiasm; and parachiasmal, passing forward from the anterior wall of the parent carotid artery and over the anterior clinoid process into the anterior fossa. The suprachiasmal type is the rarest. Almeida's series included none of nine cases," Ferguson and Drake's one of 10,5) and Yasargil's seven of 30.21)In the past 12 years, we have en countered 46 carotid-ophthalmic artery aneurysms at our department, but only two (4.3%) were of the suprachiasmal type. The nomenclature for proximal ICA aneurysms varies. Some authors have grouped aneurysms arising from the ventral wall of the ICA separately from carotid-ophthalmic artery aneurysms as ven tral or paraclinoid aneurysms because of the con siderable surgical difficulty .6,11,20) Aneurysms in the region of the carotid dural ring may originate in the cavernous sinus or the carotid cave .3,9)Rhoton 16) found that saccular aneurysms arise from a curve of the parent artery at the junction with an arterial branch. Day') classified aneurysms arising from the ophthalmic segment of the ICA into ophthalmic artery aneurysms and superior hypophyseal artery aneurysms. In general, ICA aneurysms may arise from the medial, lateral, ventral, or dorsal walls. The rare suprachiasmal type of carotid-ophthalmic artery aneurysm develops from the dorsal wall of the ICA just distal to the origin of the ophthalmic artery. Our previous report also considered ICA dorsal wall aneurysms as unusual."" The suprachiasmal projec

tion of carotid-ophthalmic artery aneurysms may result from either the origin of the ophthalmic artery from the ICA lying relatively lateral to the optic nerve (due to sporadic variation of the ophthalmic artery or sclerosis of the ICA), or to the limited space below the ophthalmic artery, ICA, and optic nerve surrounded by bone which hinders aneurysm growth below the optic nerve. Carotid-ophthalmic artery aneurysms tend to become large, 4'5'7 as in our two cases, which were discovered incidentally. A suprachiasmal aneurysm may grow large because there are no limiting struc tures, and is not discovered because no visual symp toms occur at the early stage. Carotid-ophthalmic artery aneurysms are less liable to rupture than those at other sites.5) Day') suggested a "double" protec tive layer that reduces liability to hemorrhage in many lesions of the ophthalmic segment. Certainly, the ventral type of carotid-ophthalmic artery aneurysm is protected from rupture by the overlying ICA and the lateral inferior dural wall: For the medial or subchiasmal type, the undersurface of the optic nerve and the lateral dural wall act similarly. Another possibility is that the pathogenesis of this aneurysm is different from other saccular aneurysms. Nakagawa et al.") reported dorsal ICA aneurysms, which were undoubtedly different, appearing as small, wide-based, fragile, and unconnected with arterial branching. Our two cases did not present with visual distur bances in spite of the large size. In contrast, carotid ophthalmic artery aneurysms growing below the op tic nerve do tend to produce visual defects.") Preoperative angiography showed aneurysmal sacs projecting superomedially in both our cases. A large carotid-ophthalmic artery aneurysm with supero medial projection and absence of visual disturbance indicates the suprachiasmal type. CT and sagittal magnetic resonance (MR) imaging may confirm this diagnosis by demonstrating the chiasm-aneurysm relationship.",") Direct clipping of carotid-ophthalmic artery aneurysms is possible using modern surgical aids such as the diamond drill, Doppler ultrasonography, and better clips of various sizes and shapes. The surgical treatment of giant aneurysms has also been simplified by large clips with extremely high closing pressures. 18) The ipsilateral pterional approach with partial removal of the anterior clinoid process and unroofing of the optic canal allows securing the prox imal parent artery and visualizing the ophthalmic artery and aneurysm. More importantly, complete clipping without causing stenosis of the parent artery

is possible.',',',`) A contralateral approach may be useful for medial-ventrally protruding aneurysms, 12) but proximal control of the parent artery can be very difficult. A combined epi and subdural approach has also been described for a unilateral carotid ophthalmic artery aneurysm.') A large carotid ophthalmic artery aneurysm was successfully obliterated by clipping the aneurysmal neck and in jecting cyanoacrylate into the body.") We used the ipsilateral pterional approach to ex pose the proximal ICA and ophthalmic artery to clarify the local anatomy. This necessitates removal of the anterior clinoid process and unroofing of the optic canal, and cutting the carotid dural ring, especially for proximal ICA aneurysms.') Supra chiasmal carotid-ophthalmic artery aneurysms re quire careful retraction of the frontal lobe since the aneurysmal dome is usually attached. The aneurysmal sac in Case 1 was punctured to decrease the size and tension and to avoid occlusion of the parent or daughter arteries during clipping. This was not required in Case 2 since the aneurysm was suffi ciently decompressed with three clips, and the optic nerve was also decompressed. Detection and se curing of the optic nerve are important during dis section, as it may be very thin due to compression, or displaced deeper or into unusual locations. When the optic nerve is difficult to find, it should be iden tified distally near the chiasm and then traced back toward the optic canal. Every effort should be made to preserve the optic nerve both anatomically and functionally. Case 1 developed a postoperative nasal visual field defect in the left eye, possibly related to surgical manipulation of the optic nerve. Visual distur bances, ranging from optic blindness to visual field defects, after direct surgery on carotid-ophthalmic artery aneurysms have occurred in 15-33% of pa tients in different series. 1,2,1,1) We planned surgical intervention in our cases to prevent subsequent rupture of the large aneurysms. The malignant course of giant aneurysms, contrary to what used to be believed, encourages surgical in tervention. 15) The suprachiasmal carotid-ophthalmic artery aneurysm is a rare type that develops from the dorsal wall of the ICA just distal to the origin of the ophthalmic artery. ICA aneurysms may arise from the medial, lateral, ventral, or dorsal walls. This classification provides an accurate description of the aneurysmal anatomy with much less confusion to the surgeon. The suprachiasmal carotid-ophthalmic artery aneurysm can therefore be called a proximal dorsomedial ICA aneurysm. A suprachiasmal

carotid-ophthalmic

artery

aneurysm

is strongly

sus

pected when preoperative angiography reveals a superomedial carotid-ophthalmic artery aneurysm without visual disturbances. Postcontrast CT and sagittal MR imaging may help to confirm this diag nosis. Direct surgery for clipping of a suprachias mal aneurysm is now feasible with recent micro surgical innovations and should be carried out to prevent rysms.

rupture

of

these

frequently

large

11)

Nakagawa F, Kobayashi S, Takemae T, Sugita K: Aneurysms protruding from the dorsal wall of the in ternal carotid artery. J Neurosurg 65: 303-308 . 1986 Nakao S, Kikuchi H, Takahashi N: Successful clip

12)

ping of carotid-ophthalmic aneurysms through a contralateral pterional approach. Report of two cases. J Neurosurg 54: 532-536, 1981 Nishimoto A, Kuyama H, Nagao S, Kinugasa K, Artificial embolization with isobutyl-2-Kunishio K cyanoacrylate for treatment of carotid-ophthalmic aneurysm. Surg Neurol 28: 46-50, 1987 Nutik SL: Carotid paraclinoid aneurysms with in tradural origin and intracavernous location. J Neurosurg 48: 526-533, 1978

13)

aneu 14)

References 1) 2)

3)

4)

5)

6)

7)

Almeida GM, Sibata MK, Bianco E: Carotid ophthalmic aneurysm. Surg Neurol 5: 41-45, - 1976 Benedetti A, Curri D: Direct attack on carotid ophthalmic and large internal carotid aneurysms. Surg Neurol 8: 49-54, 1977 Day AL: Aneurysms of the ophthalmic segment. A clinical and anatomical analysis. J Neurosurg 72: 677-691, 1990 Dolenc VV: A combined epi- and subdural direct ap proach to carotid-ophthalmic artery aneurysms. J Neurosurg 62: 667-672, 1985 Ferguson GG, Drake CG: Carotid-ophthalmic aneurysms: The surgical management of these cases presenting with compression of the optic nerves and chiasm alone. Clin Neurosurg 27: 263-308, 1980 Fox JL: Microsurgical treatment of ventral (para clinoid) internal carotid aneurysms. Neurosurgery 22: 32-39, 1988 Guidetti B, La Torre E: Management of carotid ophthalmic aneurysms. J Neurosurg 42: 438-442, 1975

8) Heros RC, Nelson PB, Ojemann RG, Crowell RM, De Brun G: Large and giant paraclinoid aneurysms: Surgical techniques, complications, and results. Neurosurgery 12: 153-162, 1983 9)

10)

Kobayashi S, Kyoshima K, Gibo H, Hegde SA, Takemae T, Sugita K: Carotid cave aneurysms of the internal carotid artery. J Neurosurg 70: 216-221, 1989 Kothandaram P, Dawson BH, Kruyt RC: Carotid ophthalmic aneurysms. A study of 19 patients. J Neurosurg 34: 544-548, 1971

15) Peerless SJ, Wallace MC, Drake CG: Giant in tracranial aneurysms, in Youmans JR (ed): Neurological Surgery: A Comprehensive Reference Guide to the Diagnosis and Management of Neurosurgical Problems, vol 3. Philadelphia, WB Saunders, 1990, pp 1742-1763 16) 17)

18)

19)

20) 21)

Rhoton AL Jr: Anatomy of saccular aneurysms. Surg Neurol 14: 59-66, 1980 Schmid UD, Steiger HJ, Huber P: Accuracy of high resolution computed tomography in direct diagnosis of cerebral aneurysms. Neuroradiology 29: 152-159, 1987 Sugita K, Kobayashi S, Inoue T, Takemae T: Characteristics and use of ultra-long aneurysm clips. J Neurosurg 60: 145-150, 1984 Worthington BS, Kean DM, Hawkes RC , Holland GN, Moore WS, Corston R: NMR imaging in the recognition of giant intracranial aneurysms. AJNR 4: 835-836, 1983 Yasargil MG: Microneurosurgery. Stuttgart, Georg Thieme, 1984, pp 43-57 Yasargil MG, Gasser JC, Hodosh RM, Rankin TV: Carotid-ophthalmic aneurysms: Direct microsurgical approach. Surg Neurol 8: 155-165, 1977

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Neurosurgery,

Medicine, Japan.

3-1-1

to: A. Diraz, Shinshu Asahi,

M.D.,

University Matsumoto,

Department School Nagano

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