Height of aneurysm neck and estimated extent of brain retraction: powerful predictors of olfactory dysfunction after surgery for unruptured anterior communicating artery aneurysms.
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.
Department of Neurosurgery.|Research Center for Neurosurgical Robotic Systems, Kyungpook National University, Daegu; and.
Jaechan
J
Park
Department of Neurosurgery.
Wonsoo
W
Son
Department of Neurosurgery.
Duck-Ho
DH
Goh
Department of Neurosurgery.
Dong-Hun
DH
Kang
Department of Molecular Medicine, and.
Joomi
J
Lee
Department of Medical Statistics, School of Medicine, Catholic University of Daegu, Republic of Korea.
Im Hee
IH
Shin
D000368:Aged; D002533:Cerebral Angiography; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D006801:Humans; D015994:Incidence; D002532:Intracranial Aneurysm / Q000150:complications / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D000857:Olfaction Disorders / Q000175:diagnosis / Q000453:epidemiology*; D009832:Olfactory Nerve / Q000473:pathology; D012372:ROC Curve; D012307:Risk Factors; D014057:Tomography, X-Ray Computed
ACoA = anterior communicating artery; AUC = area under the ROC curve; CTA = CT angiography; DSA = digital subtraction angiography; ROC = receiver operating characteristic; SAH = subarachnoid hemorrhage; anosmia; anterior communicating artery; craniotomy; intracranial aneurysm; treatment outcome; vascular disorders