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ORIGINAL ARTICLE
Year : 2018  |  Volume : 18  |  Issue : 1  |  Page : 27-31

Cadaveric study on the course of vertebral artery and variation on entry level


Department of Orthopedics, Burdwan Medical College, Bardhaman, West Bengal, India

Date of Web Publication15-Feb-2018

Correspondence Address:
Soumyadeep Duttaroy
Room No-11, J.R. Hostel, Burdwan Medical College, Bardhaman - 713 104, West Bengal
India
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DOI: 10.4103/sjsm.sjsm_28_17

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  Abstract 


Background: Thorough knowledge of anatomy of vertebral artery is essential to avoid inadvertent injury during surgery. The vertebral artery can have a variable course, especially in the upper cervical spine.
Materials and Methods: Study area - Burdwan Medical College and Hospital. Study population - Cadaver at Anatomy and FSM Department. Sample size - Thirty-one cadavers. Study design - Institution-based prospective study. In this study, most of the dissection is done through midline incision to avoiding risk in damage to trachea and esophagus. All structures are bluntly dissected to reach the origin of vertebral artery. From there, the level of entry is dissected.
Results: Out of 31 cadavers, male cadavers were 22 (71%) and female cadavers were 9 (29%). Anomalous vertebral artery entry found only in 3 (9.7%) cases. All anomalous entry was at C7 level. Vertebral artery entry at C6 foramen in 28 cases (90.3%). In all the 28 cases where vertebral artery entered at C6 transverse foramina, vertebral artery ascended from subclavian artery as it's first branch. Among 28 cases where vertebral artery entered at C6, 20 cases were males and eight cases were females. Out of three cases having C7 entry, two were male cases and one was female case. Altogether 9.7% of cases had C7 anomalous entry.
Conclusion: In our study from 31 cadavers, we found 9.7% of cases have anomalous entry at C7 level. Although this is a small study with few cadaver number of anomalous connection is not small, and it is not at all rare.

  Abstract in Arabic 

الخلفية: المعرفة الشاملة لتشريح الشريان الفقري أمر ضروري لتجنب إصابة غير مقصودة أثناء الجراحة. ذلك ان الشريان الفقري يمكن أن يكون لها مسار متغير، وخاصة في العمود الفقري العنقي العلوي.
المواد والطرق: منطقة الدراسة كلية الطب والمستشفى فى بوردوان. وتتكون حجم العينة من واحد وثلاثون جثة. وكان تصميم الدراسة مؤسسا على دراسة مستقبلية يتم فيها التشريح من خلال شق خط الوسط لتجنب المخاطر في الأضرار التي قد تلحق بالقصبة الهوائية والمريء. يتم تشريح جميع الهياكل للوصول إلى أصل الشريان الفقري. من هناك، يتم تشريح مستوى الدخول.
النتائج: من بين 31 جثة، كان الذكور 22 (71٪)، وكانت جثث الإناث 9 (29٪). الشذوذ دخول الشريان الفقري وجدت فقط في 3 (9.7٪) حالات. وكان كل الدخول الشاذ للشريان الفقري في مستوى C7. ومدخل الشريان الفقري في الثقبة C6 في 28 حالة (90.3٪). وفي جميع الحالات ال 28 حيث كان مدخل الشريان الفقري في C6 ثقبا عرضيا، وصعود الشريان الفقري من الشريان تحت الترقوة كما أول فرع. من بين 28 حالة حيث دخلت الشريان الفقري في C6، 20 حالة من الذكور و8 حالات من الإناث. ومن بين الحالات الثلاث التي الدخول فيها C7، كان هناك حالتان من الذكور، وواحدة من الحالات النسائية. وبلغ مجموع الحالات التي ,وجد فيها الدخول في C7 شاذا 9.7٪ من الحالات.
الخلاصة: في دراسة اشتملت على 31 جثة، وجدنا 9.7٪ من الحالات لها دخولا شاذا للشريان الفقري في مستوى C7. على الرغم من أن هذا هو دراسة صغيرة مع عدد قليل من الجثث الال ان الملاحظة الشاذة للشريان الفقري ليست صغيرة، وأنها ليست على الإطلاق نادرة.

Keywords: Cadaveric dissection, vertebral artery anatomy, vertebral artery anomaly


How to cite this article:
Ghosh S, Chatterjee B, Ray MK, Duttaroy S, Islam S, De C. Cadaveric study on the course of vertebral artery and variation on entry level. Saudi J Sports Med 2018;18:27-31

How to cite this URL:
Ghosh S, Chatterjee B, Ray MK, Duttaroy S, Islam S, De C. Cadaveric study on the course of vertebral artery and variation on entry level. Saudi J Sports Med [serial online] 2018 [cited 2018 Aug 14];18:27-31. Available from: http://www.sjosm.org/text.asp?2018/18/1/27/225289




  Introduction Top


Iatrogenically, apart from instrumentation in cervical spine region,[1],[2] epidural injection [3] and abscess drainage due to cervical spine infection like tuberculosis can damage the vertebral artery.

Thorough knowledge of anatomy of vertebral artery is essential to avoid inadvertent injury during surgery.[4],[5],[6],[7] The vertebral artery can have a variable course, especially in the upper cervical spine.

The present study is a cadaveric study on the course of vertebral artery, especially variation on entry and exit, in Burdwan Medical College.


  Materials and Methods Top


Study area - Burdwan Medical College and Hospital.

Study population - Cadaver at Anatomy and FSM Department.

Sample size – Thirty-one cadavers.

Study design - Institution-based prospective study.

In this study, most of the dissection is done through midline incision to avoid risk to damaging trachea and esophagus. All structures are bluntly dissected to reach the origin of vertebral artery. From there, the level of entry is dissected.

A longitudinal incision parallel to the anterior border of the sternocleidomastoid is used. Following the skin incision, the platysma is divided in line with its muscle fibers. The deep cervical fascia investing the sternocleidomastoid is then incised, carotid sheath identified and with blunt retractors protecting the soft-tissue structures medially and laterally, the pretracheal fascia is separated medial to the carotid sheath. The prevertebral fascia may be swept away using blunt dissection with peanut sponges. The longitudinal fibers of the anterior longitudinal ligament are then visualized spanning the vertebral bodies and intervertebral discs.[8],[9]

In most of the cases for proper viewing, trachea, and esophagus are removed. Both carotid and subclavian artery is dissected. Subclavian artery is dissected for easier identification of vertebral artery origin. First rib is located and first thoracic vertebra is identified and marked as T1. After that, all the cervical vertebra are demarcated in ascending manner, and proper entry level of vertebral artery through transverse foramina is located and marked.


  Results Top


Out of 31 cadavers, male cadavers were 22 (71%) and female cadavers were 9 (29%) [Table 1].
Table 1: Distribution according to sex

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Vertebral artery entry at C6 foramen in 28 cases (90.3%) [Table 2]. In 28 cases, vertebral artery ascending from subclavian artery as its first branch and enter at the level of C6 transverse foramen [Figure 1], [Figure 2], [Figure 3]. Anomalous vertebral artery entry found only in three (9.7%) cases [Table 2] and [Figure 4], [Figure 5], [Figure 6], [Figure 7]. Among 28 cases where vertebral artery entered at C6, 20 cases were males and eight cases were females [Table 3]. All anomalous entry at C7 level [Figure 8].
Figure 1: Vertebral artery entering at C6 marked by tape

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Figure 2: Bilateral vertebral artery entering at C6 marked by instruments

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Figure 3: Vertebral artery entering at C6 marked by a Bard-Parker handle

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Figure 4: Vertebral artery entering at C7 marked by a dissecting Mayo scissor

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Figure 5: Vertebral artery entering at C6 as marked by a plain forceps

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Figure 6: Vertebral artery entering at C6 marked by finger

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Figure 7: Vertebral artery entering at C6 marked by placement of Mayo scissor

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Figure 8: Vertebral artery entering at C7 as marked here by pulling with a dissecting Mayo scissor

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Table 2: Distribution According To Vertebral Level Entry

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Table 3: Arterial Vertebral level entry with sex

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Out of three C7 entries, two were male cases and one was female case [Table 3].

Altogether 9.7% of cases had C7 anomalous entry.


  Discussion Top


The present study is not comparable with the works of Hong et al.[10] where vertebral artery entered the C6 transverse process in 94.9% of the specimens. Abnormal entrance was observed in 5.1% of the specimens, with entrance into the C4, C5, or C7 transverse foramen 1.6%, 3.3%, and 0.3%, respectively.

Jovanovic et al.[11] evaluated the individual variations of the foramen transversarium of the seventh cervical vertebra. This foramen sometimes has the same dimensions as the foramina of the other cervical vertebrae, but it can also be smaller, or absent. In cases where a foramen is present in the seventh cervical vertebra, vascular or nerve structures (or both) can be occasionally observed within. According to results, vertebral artery enters at C7 only in 5% of cases.

Wakao et al.[12] showed that vertebral artery entered the C6 transverse foramen in 95.6% of specimens. Out of 919 subjects, 67 (7.3%) had unilateral anomaly and 7 (0.8%) had a bilateral anomaly. An abnormal level of entrance was observed in 8.1% of subjects (74 of 919 patients), and 4.4% of specimens (81 of 1838 courses), with a level of entrance into the C4, C5, or C7 transverse foramen in 0.5% (n = 10), 3.1% (n = 57), and 0.8% (n = 14) of all specimens. (P < 31.01; t-test). Computed tomography (CT) angiography is recommended in cases with an uneven transverse foramen for confirming vascular anomaly.

Meila et al.[13] retrospectively reviewed CT angiography of 539 patients using a contrast-enhanced protocol of the vertebral artery on CT. 94.2% of left vertebral artery originated from the left subclavian artery and entered the transverse foramen at C6 in nearly all cases. 6.3% of the left vertebral artery (male = 4%, female = 10%) originated from the aortic arch and entered the transverse foramen either at C4, C5, or C7 but never at C6. One case of an aberrant retroesophageal right vertebral artery originated from the aortic arch distal to the left subclavian artery and entered at C7 (0.19%).

Takeuchi et al.[14] exhibited an anomalous presence of anterior tubercles, and 0.3% of patients displayed cervical ribs at the C7 transverse process. The prevalence of anomalies was significantly higher in men aged <40 years than in older men (P < 31.001), whereas the prevalence was not higher in women aged <40 years than in older women. The prevalence of vertebral artery entry into the C7 transverse foramen was 0.6%. Although an anomalous vertebral artery entry into the C7 transverse foramen was rare.

Conclusion

In our study from 31 cadavers, we found 9.7% of cases have anomalous entry at C7 level. Though this is a small study with few cadaver but number of anomalous connection is not small and it is not at all rare.

Acknowledgment

We would like to thank Prof. (Dr.) Chinmay De, Professor and Head of the Department of Orthopaedics. His valuable advice and supervision were instrumental for completion of this project.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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[PUBMED]    
2.
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Hong JT, Park DK, Lee MJ, Kim SW, An HS. Anatomical variations of the vertebral artery segment in the lower cervical spine: Analysis by three-dimensional tomography angiography. Spine 2008; 33:2422-6.  Back to cited text no. 10
    
11.
Jovanovic MS. A comparative study of the foramen tranversarium of the sixth and seventh cervical vertebrae. Surg Radiol Anat 1990;12:167-72.  Back to cited text no. 11
    
12.
Wakao N, Takeuchi M, Nishimura M, Riew KD, Kamiya M, Hirasawa A, et al. Vertebral artery variations and osseous anomaly at the C1-2 level diagnosed by 3D CT angiography in normal subjects. Neuroradiology. 2014;56:843-9.  Back to cited text no. 12
    
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Miele VJ, Panjabi MM, Benzel EC. Anatomy and biomechanics of the spinal column and cord. Handb Clin Neurol 2012;109:31-43.  Back to cited text no. 13
    
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Takeuchi M, Aoyama M, Wakao N, Tawada Y, Kamiya M, Osuka K, et al. Prevalence of C7 level anomalies at the C7 level: an important landmark for cervical nerve ultrasonography. Acta Radiologica 2015;57:318-24.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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