Height of aneurysm neck and estimated extent of brain retraction: powerful predictors of olfactory dysfunction after surgery for unruptured anterior communicating artery aneurysms

Abstract

A pterionAl approach and its modifications are commonly used for clipping most anterior circulation aneurysms. In such an approach, the frontal lobe and olfactory nerve are both retracted to some degree to access aneurysms located in the circle of Willis. In particular, in cases of an anterior communicating artery (ACoA) aneurysm, a retractor is placed across the olfactory tract, which is damaged primarily by retractor pressure and strain. Thus, olfactory dysfunction following a pterional approach occurs most frequently in cases of ACoA aneuaBBreViatiONS ACoA = anterior communicating artery; AUC = area under the ROC curve; CTA = CT angiography; DSA = digital subtraction angiography; ROC = receiver operating characteristic; SAH = subarachnoid hemorrhage. OBJectiVe The highest incidence of olfactory dysfunction following a pterional approach and its modifications for an intracranial aneurysm has been reported in cases of anterior communicating artery (ACoA) aneurysms. The radiological characteristics of unruptured ACoA aneurysms affecting the extent of retraction of the frontal lobe and olfactory nerve were investigated as risk factors for postoperative olfactory dysfunction. methOdS A total of 102 patients who underwent a pterional or superciliary keyhole approach to clip an unruptured ACoA aneurysm from 2006 to 2013 were included in this study. Those patients who complained of permanent olfactory dysfunction after their aneurysm surgery, during a postoperative office visit or a telephone interview, were invited to undergo an olfactory test, the Korean version of the Sniffin' Sticks test. In addition, the angiographic characteristics of ACoA aneurysms, including the maximum diameter, the projecting direction of the aneurysm, and the height of the neck of the aneurysm, were all recorded based on digital subtraction angiography and sagittal brain images reconstructed using CT angiography. Furthermore, the extent of the brain retraction was estimated based on the height of the ACoA aneurysm neck. reSultS Eleven patients (10.8%) exhibited objective olfactory dysfunction in the Sniffin' Sticks test, among whom 9 were anosmic and 2 were hyposmic. Univariate and multivariate analyses revealed that the direction of the ACoA aneurysm, ACoA aneurysm neck height, and estimated extent of brain retraction were statistically significant risk factors for postoperative olfactory dysfunction. Based on a receiver operating characteristic (ROC) analysis, an ACoA aneurysm neck height > 9 mm and estimated brain retraction > 12 mm were chosen as the optimal cutoff values for differentiating anosmic/hyposmic from normosmic patients. The values for the area under the ROC curves were 0.939 and 0.961, respectively. cONcluSiONS In cases of unruptured ACoA aneurysm surgery, the height of the aneurysm neck and the estimated extent of brain retraction were both found to be powerful predictors of the occurrence of postoperative olfactory dysfunction.

Recurrence and retreatment of anterior communicating artery aneurysm after endovascular treatment

“…Park et al reported objective olfactory dysfunction rate of 10.8% in their study. 16 Because of the risks of these complications, minimal invasive surgery like keyhole approach with eyebrow or palpebral incision was introduced in AcomA surgery. [17][18][19] These approaches reduced the amount of brain retraction and rectus gyrectomy.…”

Olfactory dysfunction in patients undergoing supraorbital keyhole craniotomy for clipping of unruptured aneurysms

“…The mechanisms underlying olfactory decline are multifactorial and not entirely understood (Murphy, ; Doty and Kamath, ; Mobley et al, ; Patel and Pinto, ; Attems et al, ). Park et al () analyzed 102 patients with unruptured ACOM aneurysms who underwent a pterional or supraorbital keyhole craniotomy for aneurysm clipping. They found aneurysm neck height >9 mm and estimated brain retraction >12 mm to be predictors for postoperative olfactory dysfunction.…”

“…They did not find differences in bilateral anosmia rates based on age, history of aSAH, sex, or surgical approach. Major limitations, however, are lack of individual testing of each nostril, lack of preoperative assessment and postoperative assessment only in those patients that reported subjective olfactory impairment (Park et al, ). In 2009, Moman et al () interviewed 32 patients who underwent clipping of an unruptured aneurysm since 1991.…”

“…Discrepancies between subjective experience of olfactory function and results obtained from olfactory testing underline the necessity of systematic olfactory testing to adequately identify treatment‐related olfactory deterioration in cerebral aneurysm patients (Eriksen et al, ; de Vries et al, ). Prediction of patients at risk for developing postoperative anosmia remains challenging (Park et al, ). The supraorbital keyhole craniotomy provides an elegant, effective, and minimally invasive approach for clipping of cerebral aneurysms (Fischer et al, , , ).…”

Letter to the Editor. Multiple sclerosis–related tremor and stereotactic radiosurgery

“…T O THE EDITOR: We have read with great attention the article by Park et al 8 (Park J, Son W, Kwak Y, et al: Pterional versus superciliary keyhole approach: direct comparison of approach-related complaints and satisfaction in the same patient. J Neurosurg [epub ahead of print March 2, 2018.…”