Acta Neurochir (2015) 157:43–48 DOI 10.1007/s00701-014-2253-z
TECHNICAL NOTE - VASCULAR
C1 transverse process-hyoid bone line for preoperative evaluation of the accessible internal carotid artery on carotid endarterectomy: technical note Hisashi Kubota & Yasuhiro Sanada & Hiromasa Yoshioka & Takayuki Tasaki & Jun Shiroma & Masaharu Miyauchi & Rokuya Tanikawa & Mitsuru Matsuki & Toshiho Ohtsuki & Amami Kato
Received: 23 September 2014 / Accepted: 3 October 2014 / Published online: 16 October 2014 # Springer-Verlag Wien 2014
Abstract Background The preoperative imaging diagnosis of the distal portion of the internal carotid artery (ICA) is extremely important for carotid endarterectomy (CEA). Herein the authors defined a line from the C1 transverse process to the hyoid bone (C1-H line) and evaluated whether the line can be used to predict an accessible ICA in CEA. Methods A cross point between the C1-H line and distal ICA was analyzed using three-dimensional computerized tomographic angiography (3D-CTA) in 20 patients. The C1-H line was compared to the line drawn from the mastoid process to the mandible (M-M line). Intraoperative exposure of the distal ICA was evaluated using both lines. Furthermore, the distance of each line from the C2 vertebra was measured to identify the distance difference of each line in relation to the cervical posture. Results A distal ICA exposed at a cross point of the C1-H line corresponded well with the intraoperative findings. The cross point between the C1-H line and distal ICA was positioned at an average of 7.0±0.7 mm cranially in comparison to the MM line. The C1-H line showed smaller distance differences at different cervical positions than the M-M line. The C1-H line H. Kubota (*) : Y. Sanada : H. Yoshioka : T. Tasaki : J. Shiroma : M. Miyauchi : A. Kato Department of Neurosurgery, Kinki University Faculty of Medicine, 377-2, Onohigashi, Osakasayama, Osaka 589-8511, Japan e-mail: [email protected] R. Tanikawa Teishinkai Hospital Stroke Center, Hokkaido, Japan M. Matsuki Department of Radiology, Kinki University Faculty of Medicine, Osaka, Japan T. Ohtsuki Stroke Center, Kinki University Faculty of Medicine, Osaka, Japan
moved an average of 2.8±2.5 mm from a cervical neutral position to an extensional one in the perpendicular direction. Conclusion The C1-H line measured by 3D-CTA is a simple and useful indicator of the distal ICA exposure in the preoperative diagnosis for CEA. Keywords Carotid endarterectomy . C1 transverse process . Hyoid bone . Internal carotid artery . Three-dimensional computerized tomographic angiography
Introduction High positioning of internal carotid plaque in carotid endarterectomy (CEA) entails high risks of morbidity; therefore, preoperative evaluation of the distal internal carotid artery (ICA) is necessary for safe treatment of cervical stenotic lesions. A line drawn from the tip of the mastoid process to the angle of the mandible (M-M line) is considered the upper limit of the accessible distal ICA in standard CEA procedures [2]. The M-M line is easy to confirm by palpation of the body surface, but occasionally it is not feasible to evaluate intraoperative distal ICA exposure because of the large variability of the movement of the angle of the mandible between the cervical neutral and extensional postures. This is the reason why we considered a new indicator for predicting the distal ICA exposure in the standard anterior sternocleidomastoid (SCM) approach in CEA. The landmarks obstructing good exposure with the standard anterior SCM approach have been reported as the posterior belly of the digastric muscle, the hypoglossal nerve and the C2 vertebra [1, 5]. These obstacles are not only related to the anatomical configuration, but also to the surgical access to ICA lesions. If the route of the surgical approach is in the posterolateral direction, the angle of the mandible is not a
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Acta Neurochir (2015) 157:43–48
major obstacle during an approach to the distal ICA [1]. However, in the anterolateral direction, the mandible interferes with the approach route. Therefore, an additional maneuver such as mandibular subluxation [3, 5] and a mouthpiece [9] are required to move the mandible out of the route. Our CEA approach uses a posterolateral route, and the transverse process of the C1 vertebra is confirmed during the surgical procedure. The purpose of this study is to determine whether a newly defined line from the C1 transverse process to the hyoid bone (C1-H line) can predict the accessible distal ICA in the standard anterior SCM approach.
Methods Twenty patients with symptomatic or asymptomatic cervical ICA stenotic lesions undergoing CEA with a standard anterior SCM approach were studied. The study was conducted ethically based on the Declaration of Helsinki, and informed consent was obtained from the study subjects and patients. All carotid lesions were evaluated by three-dimensional computerized tomographic angiography (3D-CTA). Contrastenhanced CT was captured in 2.5-mm slices using a multidetector row CT (Toshiba Aquilion Prime, Tochigi, Japan, or GE Discovery CT750 HD, USA). The data were analyzed, and a 3D image was reconstructed using Ziostation software (Ziosoft Inc., Tokyo, Japan). The C1-H line was defined as a line from the center of the C1 transverse process to the most superior point at the junction of the hyoid bone body and greater horn. A line drawn from the tip of the mastoid process to the angle of the mandible was used as the M-M line, as shown in a previous paper [2]. A cross point between the distal ICA and C1-H line was compared with the point between the distal ICA and M-M line at a lateral view. If the distance difference was within 5 mm, both lines were defined as locating the same position because the caliber of the ICA is estimated at approximately 5 mm. The intraoperative exposure of the distal ICA was evaluated with preoperative 3DCTA findings based on each line. To elucidate a movement distance of the C1-H line and the M-M line in relation to cervical posture, the position of each line at a different cervical posture was analyzed by a lateral Xray radiograph. In 50 patients (25 males and 25 females), 41 to 79 years of age without cervical vertebral disease, the distance between an anteroinferior point of the C2 vertebral body and each line was measured at neutral and extensional neck positions as a C2 coordinate system (Fig. 1). The results were calculated by a Microsoft Excel spreadsheet for analysis (Microsoft Corp., Redmond, WA, USA). The Fisher exact test and t test were used to compare continuous variables. Differences at P
TECHNICAL NOTE - VASCULAR
C1 transverse process-hyoid bone line for preoperative evaluation of the accessible internal carotid artery on carotid endarterectomy: technical note Hisashi Kubota & Yasuhiro Sanada & Hiromasa Yoshioka & Takayuki Tasaki & Jun Shiroma & Masaharu Miyauchi & Rokuya Tanikawa & Mitsuru Matsuki & Toshiho Ohtsuki & Amami Kato
Received: 23 September 2014 / Accepted: 3 October 2014 / Published online: 16 October 2014 # Springer-Verlag Wien 2014
Abstract Background The preoperative imaging diagnosis of the distal portion of the internal carotid artery (ICA) is extremely important for carotid endarterectomy (CEA). Herein the authors defined a line from the C1 transverse process to the hyoid bone (C1-H line) and evaluated whether the line can be used to predict an accessible ICA in CEA. Methods A cross point between the C1-H line and distal ICA was analyzed using three-dimensional computerized tomographic angiography (3D-CTA) in 20 patients. The C1-H line was compared to the line drawn from the mastoid process to the mandible (M-M line). Intraoperative exposure of the distal ICA was evaluated using both lines. Furthermore, the distance of each line from the C2 vertebra was measured to identify the distance difference of each line in relation to the cervical posture. Results A distal ICA exposed at a cross point of the C1-H line corresponded well with the intraoperative findings. The cross point between the C1-H line and distal ICA was positioned at an average of 7.0±0.7 mm cranially in comparison to the MM line. The C1-H line showed smaller distance differences at different cervical positions than the M-M line. The C1-H line H. Kubota (*) : Y. Sanada : H. Yoshioka : T. Tasaki : J. Shiroma : M. Miyauchi : A. Kato Department of Neurosurgery, Kinki University Faculty of Medicine, 377-2, Onohigashi, Osakasayama, Osaka 589-8511, Japan e-mail: [email protected] R. Tanikawa Teishinkai Hospital Stroke Center, Hokkaido, Japan M. Matsuki Department of Radiology, Kinki University Faculty of Medicine, Osaka, Japan T. Ohtsuki Stroke Center, Kinki University Faculty of Medicine, Osaka, Japan
moved an average of 2.8±2.5 mm from a cervical neutral position to an extensional one in the perpendicular direction. Conclusion The C1-H line measured by 3D-CTA is a simple and useful indicator of the distal ICA exposure in the preoperative diagnosis for CEA. Keywords Carotid endarterectomy . C1 transverse process . Hyoid bone . Internal carotid artery . Three-dimensional computerized tomographic angiography
Introduction High positioning of internal carotid plaque in carotid endarterectomy (CEA) entails high risks of morbidity; therefore, preoperative evaluation of the distal internal carotid artery (ICA) is necessary for safe treatment of cervical stenotic lesions. A line drawn from the tip of the mastoid process to the angle of the mandible (M-M line) is considered the upper limit of the accessible distal ICA in standard CEA procedures [2]. The M-M line is easy to confirm by palpation of the body surface, but occasionally it is not feasible to evaluate intraoperative distal ICA exposure because of the large variability of the movement of the angle of the mandible between the cervical neutral and extensional postures. This is the reason why we considered a new indicator for predicting the distal ICA exposure in the standard anterior sternocleidomastoid (SCM) approach in CEA. The landmarks obstructing good exposure with the standard anterior SCM approach have been reported as the posterior belly of the digastric muscle, the hypoglossal nerve and the C2 vertebra [1, 5]. These obstacles are not only related to the anatomical configuration, but also to the surgical access to ICA lesions. If the route of the surgical approach is in the posterolateral direction, the angle of the mandible is not a
44
Acta Neurochir (2015) 157:43–48
major obstacle during an approach to the distal ICA [1]. However, in the anterolateral direction, the mandible interferes with the approach route. Therefore, an additional maneuver such as mandibular subluxation [3, 5] and a mouthpiece [9] are required to move the mandible out of the route. Our CEA approach uses a posterolateral route, and the transverse process of the C1 vertebra is confirmed during the surgical procedure. The purpose of this study is to determine whether a newly defined line from the C1 transverse process to the hyoid bone (C1-H line) can predict the accessible distal ICA in the standard anterior SCM approach.
Methods Twenty patients with symptomatic or asymptomatic cervical ICA stenotic lesions undergoing CEA with a standard anterior SCM approach were studied. The study was conducted ethically based on the Declaration of Helsinki, and informed consent was obtained from the study subjects and patients. All carotid lesions were evaluated by three-dimensional computerized tomographic angiography (3D-CTA). Contrastenhanced CT was captured in 2.5-mm slices using a multidetector row CT (Toshiba Aquilion Prime, Tochigi, Japan, or GE Discovery CT750 HD, USA). The data were analyzed, and a 3D image was reconstructed using Ziostation software (Ziosoft Inc., Tokyo, Japan). The C1-H line was defined as a line from the center of the C1 transverse process to the most superior point at the junction of the hyoid bone body and greater horn. A line drawn from the tip of the mastoid process to the angle of the mandible was used as the M-M line, as shown in a previous paper [2]. A cross point between the distal ICA and C1-H line was compared with the point between the distal ICA and M-M line at a lateral view. If the distance difference was within 5 mm, both lines were defined as locating the same position because the caliber of the ICA is estimated at approximately 5 mm. The intraoperative exposure of the distal ICA was evaluated with preoperative 3DCTA findings based on each line. To elucidate a movement distance of the C1-H line and the M-M line in relation to cervical posture, the position of each line at a different cervical posture was analyzed by a lateral Xray radiograph. In 50 patients (25 males and 25 females), 41 to 79 years of age without cervical vertebral disease, the distance between an anteroinferior point of the C2 vertebral body and each line was measured at neutral and extensional neck positions as a C2 coordinate system (Fig. 1). The results were calculated by a Microsoft Excel spreadsheet for analysis (Microsoft Corp., Redmond, WA, USA). The Fisher exact test and t test were used to compare continuous variables. Differences at P
