Partial Resection of the Gyrus Rectus in Pterional Approach to Anterior Communicating Artery Aneurysms Tohru

HORIKOSHI,

Hideaki

and Department

NUKUI,

Masami

of Neurosurgery,

Shigeru

MITSUKA

KANEKO

Yamanashi Medical

College, Yamanashi

Abstract The

effect

of partial

outcome

was

resection

evaluated

in

aneurysms.

Resection

was

stage,

with

superiorly

directed

were

graded

into

Scale.

Outcomes

tients

without

Key words: gyrus

three

of the gyrus

performed

stages,

for 52 patients resection.

anterior

rectus

194 consecutive

There

more

and with

the follow-up

receiving

gyrus

were no apparent

communicating

artery,

results rectus

with

aneurysm,

poor

caused

approach

using

, in the acute . The surgical results the Glasgow Outcome with those

by gyrus

resection

pterional

approach

artery

grade

were compared rectus

on surgical

communicating

clinical

aneurysms

five stages

resection

effects

,

for 142 pa on outcome

.

outcome,

rectus

proach in many cases is the necessity to resect the gyrus rectus to visualize the aneurysmal neck. The in terhemispheric approach to anterior communicating artery aneurysms',', 16,22)has the advantage of preser vation of the gyrus rectus.10'21'25,35) However, no statistical analysis has evaluated the influence of gyrus rectus resection on surgical results. Here, we report a retrospective study of 194 consecutive cases to determine the effect of gyrus rectus resection on surgical outcome.

Clinical

Materials

and

Methods

This study included 194 consecutive patients re ceiving surgery for anterior communicating artery aneurysms. There were 121 males and 73 females, with ages ranging 14-72 years (mean 50.3 years). Preoperative clinical assessment classified the pa tients into Hunt and Kosnik grades: 106 grade I February present

into

pterional anterior

high-positioned

The pterional approach is well known and frequently used in surgery for anterior communicating artery aneurysms .6,11,12,15,29,32-34) One disadvantage of this ap

Author's

ruptured

in cases

Introduction

Received

the unilateral with

frequently

aneurysms, and

during

patients

7, 1991; address:

Accepted

T. Horikoshi,

June M.D.,

28, Nasu

cases, 22 grade la, 21 grade II, 33 grade III, 11 grade IV, and one grade V. The intervals between onset and operation was: within 3 days in 57 cases, 4-7 days in 14, 8-14 days in 25, and over 2 weeks in 98. The unilateral pterional approach was used in all cases. Angiographic indication of the dominancy of the A, segment, the direction of the aneurysmal dome and its relative position to both A2 segments were used to determine the craniotomy side. The ap proach was chosen to expose the aneurysmal neck and control any premature rupture easily. The fron tal lobe was elevated gently by a self retaining retrac tor, then the internal carotid artery and bifurcation were identified. The proximal segment of anterior cerebral artery was followed by removing the arachnoid membrane in the interhemispheric fissure toward the base of the aneurysm. If visualization and dissection of the aneurysmal neck and surround ing arteries were difficult, the posterior gyrus rectus was resected subpially using an aspirator to provide an adequate good surgical view. The resected brain was usually a few mm wide and about 1 cm long. The surgical results at discharge were compared with the preoperative neurological condition and

1991 Neurosurgical

Hospital

, Kuroiso,

Tochigi,

Japan.

classified as: improved or stable, deteriorated, and died. The follow-up results were classified using the Glasgow Outcome Scale as: excellent (normal, return to former life); good (mild neurological deficit, in dependent life possible); fair (partially dependent in daily life); poor (fully dependent, bedridden or vegetative); and died. The overall surgical results combined the surgical results with the follow-up results. Results for patients receiving gyrus rectus resection were compared with those of patients without resection. Statistical comparisons used the chi-square test.

Table

3

Overall

Table

4

Direction

outcome

of aneurysmal

dome

Results Tables 1 and 2 compare the discharge with the preoperative grade

Table

and the interval

1

Preoperative

between

clinical

operative results at Hunt and Kosnik onset

grade

and surgery

and condition

for

at

discharge

Table

2

Timing discharge

of

operation

and

condition

at

the resected and non-resected patients. Of 194 cases, 89% showed no deterioration and 6% aggravated. Ten patients (5%) died postoperatively. Mortality was higher in cases operated within 3 days. Of 52 re sected patients, 87% showed no markable deteriora tion, 8% aggravated, and 6% died. On the other hand, 90% of 142 non-resected patients showed no deterioration, 5% aggravated, and 5% died. There was no significant correlation between gyrus rectus resection and surgical results at discharge. The follow-up periods were 6 months to 1 year in 159 cases, a few years after the discharge in 35. Follow-up results of the resected patients was: 37 (71%) excellent cases, seven (13%) good, three (6%) fair, and two (4%) died. In the non-resected pa tients, 121 (85%) were excellent cases, four (3%) good, two (I%) fair, five (4%) poor, and three (2%) died. There was also no significant correlation be tween gyrus rectus resection and follow-up results. Table 3 shows that resection of the gyrus rectus had no effect on the overall surgical results. The aneurysms were classified according to their orientation to the planum sphenoidale on angiograms into: 97 (50%) anteroinferior, 75 (39%) anterosuperior, 18 (9%) posterosuperior, and only four (2%) posteroinferior aneurysms (Table 4). The distance between the aneurysmal neck and the planum sphenoidale was measured in 134 patients. The gyrus rectus was resected in 23 of 46 patients with aneurysms over 10 mm from the planum, but only 24 of 88 patients with aneurysms within 10 mm of the planum. Discussion Yasargil

et al. 14)reported

that

most cases required

the

subpial resection of the gyrus rectus to be 6-10 mm long, 2-3 mm wide, and 2-3 mm deep. Kempe"I con sidered that removal of no more than 10 mm' of brain tissue was required. Generally, a 1-2 cm inci sion of the gyrus rectus was required to visualize the proximal and distal portions of the anterior cerebral and Heubner recurrent arteries and the aneurysmal neck. 4,5,12,15,20,22,32) Similarly, we found that only a few mm wide and about 1 cm long resections at the posterior part of the gyrus rectus were required. The correlation between gyrus rectus resection and postoperative outcome has not been discussed except for a subjective judgment that no defect was detec table.30) Our study found that gyrus rectus resection did not affect the results or the quality of life after discharge. These results will encourage neurosur geons who prefer the pterional approach. The rupture of anterior communicating artery aneurysms may induce psychiatric changes, 2,18,19) such as memory disorders, including Korsakoff's syn drome,1,13,14,26,27,31) and personality changes without intellectual impairment .23,2')The symptoms are often transient, but may be persistent ,3,14,1s> resulting in se verely restricted social lives. This suggests that psychiatric syndromes may occur as a result of resec tion of the gyrus rectus. Norlen and Lindovist17 sug gested that Korsakoff s syndrome is caused by a cor tical lesion, probably in the posterior gyrus recti. Cross and Lhermitte3) found that the memory quo tient and gyrus rectus resection were related in a neuropsychological analysis of 32 patients with anterior communicating artery aneurysms. However, this association was not conclusive, because most pa tients had poor preoperative performances. Nukui et al.") found no correlation between psychiatric changes and microsurgical gyrus rectus resection in 95 patients with anterior communicating artery aneurysms. Psychiatric changes occurring after rup ture of anterior communicating artery aneurysms may be due to occlusion of perforating arteries arising from the anterior cerebral and anterior com municating arteries, or vasospasm, or massive destruction of frontal lobes. 1,7,18,20,28,31) Our study did not include intensive neuropsychological examina tions postoperatively, so mild psychiatric defects may have occurred. However, the follow-up examina tions detected no definitive psychiatric defects severe enough to affect daily life. Our study found that gyrus rectus resection was frequently required in cases with the aneurysm directed superiorly. Flamm4) and Perlmutter and Rhoton20) also found that resection is not usually needed when the aneurysm projects anteriorly or in feriorly. In contrast, Kempe and coworkers' 1,12,29,30)

proposed the gyrus rectus approach for anterior com municating artery aneurysms directed anteriorly or inferiorly to expose the aneurysmal neck before the dissection of fundi. Yasargil et al.") also recommend ed resection for prechiasmatic projecting aneurysms which hide the contralateral Al segment, or with marked looping of the A, segment. The gyrus rectus was resected more frequently in our cases with high-positioned aneurysms. Hyodo et al.') reported similar results, and considered the pterional approach optimal in most cases with low positioned anterior communicating artery aneurysms (within 12 mm of the planum sphenoidale). However, the interhemispheric approach should be considered if the neck-sphenoidale distance is over 13 mm, because the frontal lobe retraction required is more extensive, even with resection. Our study used resection more frequently in cases with poor clinical grade or in the acute stage. Possibly brain swelling, subarachnoid clots, or in tracerebral hematomas present in these poor condi tions may have been responsible. The pterional ap proach may allow removal of widespread subarach noid clots in the acute stage, to prevent delayed ischemic deficits.') Recently, operation in the acute stage has been advocated .2') Therefore, gyrus rectus resection will be performed more frequently and will become more significant in surgical procedures. Resection achieves reduced retraction of the frontal lobe, decreased risk of premature rupture, and safer clipping of the aneurysms without sacrificing the per forating arteries around the aneurysms. To protect patients from psychiatric sequelae, we consider preservation of the circulation of the anterior cerebral and perforating arteries more important than avoiding resection of the gyrus rectus. We do not wish to justify resection of normal brain tissue, but we emphasize that partial resection of the gyrus rectus is a useful method, especially in the acute stage, of visualizing anterior communicating artery aneurysms and the surrounding arteries, which can achieve safer aneurysm clipping without causing definite neurological sequelae which affect the postoperative

outcome. References

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Address

reprint

requests

to: T. Horikoshi,

ment

of Neurosurgery,

1110

Shimokato,

Yamanashi

409-38,

Yamanashi

Tamaho-machi, Japan.

M.D., Medical

Depart College,

Nakakoma-gun,