Keywords
internal jugular vein variant - carotid triangle - neck surgery
Introduction
Complications associated with neck surgery include hemorrhage,[1] nerve damage,[2] and chylous fistula.[3] Successful surgical management of carotid endarterectomy (CEA) patients is therefore
predicated on recognizing patient-specific anatomic structures that may increase the
risk of an adverse outcome. The internal jugular vein (IJV) is the largest caliber
blood vessel in the head and neck. The anatomy of this vessel is considered to be
relatively stable, so it serves as a major surgical landmark for adjacent structures
(e.g., spinal accessory nerve, carotid artery, cervical lymph nodes). Anomalies of
the IJV, including duplications and fenestrations, have been reported,[4]
[5] but few attempts have been made to characterize the prevalence of IJV location anomaly[6]
[7] in surgical cases. Variations in the location of the IJV may account for iatrogenic
IJV injuries, and might lead to IJV ligation. Adverse effects after IJV ligation include
transverse sinus thrombosis.[8] Therefore, understanding the anomalies of the IJV is important to avoid iatrogenic
damage during CEA. We report three cases of IJV anomalies in patients undergoing CEA
from 2020 to 2022 and discuss the clinical implications, operative management, and
literature describing IJV location anomaly.
Materials and Methods
Patient Assessment
We treated 60 consecutive patients with internal carotid artery stenosis by CEA from
January 2020 to December 2022. Three-dimensional computed tomography arteriography + venography
(3D CTA + V) data were obtained preoperatively, which detected twisted IJV located
anterior to the common carotid artery (CCA) in three patients (5%). All three patients
were men with left-sided IJV anomaly, as summarized in [Table 1]. All three patients underwent CEA.
Table 1
Cases with twisted internal jugular vein
|
Case no.
|
Age (y)
|
Sex
|
Stenosis (%)
|
Site
|
Comorbidity
|
Symptom
|
|
1
|
81
|
Male
|
90
|
Left
|
DM, DLp
|
−
|
|
2
|
75
|
Male
|
80
|
Left
|
HT
|
Amaurosis fugax
|
|
3
|
70
|
Male
|
50
|
Left
|
DLp
|
TIA
|
Abbreviations: DLp; dyslipidemia; DM, diabetes mellitus; HT, hypertension; TIA, transient
ischemic attack.
Surgical Technique of CEA for Patients with Twisted IJV
Under general anesthesia, a transverse skin incision was made using the left neck
crease at the level of the carotid bifurcation. After dissection of the skin flap
under the platysma muscle along to the great auricular nerve and the external jugular
vein and reaching the surface of the parotid gland, the retromandibular space was
carefully dissected along to the investing layer of the deep cervical fascia to find
the posterior belly of the digastric muscle (PBDGM). The PBDGM is dissected as far
as possible until the white tendinous part of the anterior part of the PBDGM was revealed.
The common facial vein (CFV) was found at the superficial and anterior part of the
PBDGM. Then, dissection proceeded along to the CFV caudally to find the anterior part
of the carotid sheath and IJV. After ligation and cutting of the CFV, the anterior
part of the carotid sheath with the IJV was dissected and the CCA identified, then
turned laterally to reveal the external carotid artery, CCA, and internal carotid
artery, and CEA was accomplished.
Construction of 3D CTA + V
To obtain cervical arterial and venous information, we used a 64-row multidetector
computed tomography (CT) scanner (Aquilion; Canon, Inc., Tokyo, Japan). CT was performed
according to the following parameters, briefly described as follows: 0.5-mm collimation,
3.5-mm table increment per rotation (3.5 helical pitch), 0.75-second r gantry rotation
speed, and 120 kV/300 mA. Before scanning commenced, 60 mL (350 mg I/mL) of iomeprol
contrast medium (Eisai, Tokyo, Japan) was injected via the right antecubital vein
using a power injector (Nemoto, Tokyo, Japan) at a rate of 4 mL/s. Initiation of scanning
was set with an automatic or visual bolus-tracking program, which was used to start
the first arterial phase scan after the injection of contrast medium. Six seconds
after arterial phase data acquisition, venous phase data collection was started. For
our scanner, the effective dose for the original CTA data are around 1.5 mSv, calculated
according to the National Radiological Protection Board W67. Axial slices were reconstructed
with a 0.5-mm slice thickness at 0.3-mm intervals. The images obtained were transferred
and processed using a stand-alone workstation (Ziostation 2; Ziosoft, Inc., Tokyo,
Japan).
3D CTA + V images were produced by a technician by subtracting bone density structures
using a subtraction mode in a workstation. First, subtraction images were produced
which enhanced CT image data by subtracting plain CT image data. Then, an arterial
image using 3D CTA was generated by employing a threshold technique and editing the
image manually to remove any remaining bone of the cranial base using the subtraction
image. 3D CTV image was also generated in the same manner. Then, anterior and lateral
views of the 3D CTA + V fusion image were constructed.
Case Presentation
Case 1
An 81-year-old man with diabetes mellitus and dyslipidemia was admitted for left carotid
stenosis up to 90%. 3D CTA + V revealed the IJV running anteriorly to the CCA in the
lateral view ([Fig. 1A]). Left CEA was performed. The CFV was found and dissected caudally and revealed
the IJV ([Fig. 1B]). After ligation and cutting of the CFV ([Fig. 1C]), the carotid sheath with the IJV turned laterally revealed the external carotid
artery, CCA, and internal carotid artery ([Fig. 1D]), and CEA was accomplished. The vagus nerve was found posterior to the CCA. No cerebral
infarction occurred postoperatively. He was discharged on the eighth postoperative
day without any complications.
Fig. 1 Case 1. Three-dimensional computed tomography arteriography + venography, lateral
view, revealed the left internal jugular vein (IJV) running anteriorly to the common
carotid artery (CCA) (A). The common facial vein (CFV) was found and dissected caudally and revealed the
IJV before carotid endarterectomy (B). After ligation and cutting of the CFV (C), the carotid sheath with the IJV turned laterally revealed the external carotid
artery, CCA, and internal carotid artery (D). PBDGM, posterior belly of digastric muscle.
Case 2
A 75-year-old man with hypertension presented with a 2-week history of left amaurosis
fugax and was admitted for left carotid stenosis up to 80%. 3D CTA + V revealed the
IJV running anteriorly to the CCA in the lateral view ([Fig. 2A]). Left CEA was performed. The CFV was found and dissected caudally and revealed
the IJV ([Fig. 2B]). After ligation and cutting of the CFV ([Fig. 2C]), the carotid sheath with the IJV turned laterally revealed the external carotid
artery, CCA, and internal carotid artery ([Fig. 2D]), and CEA was accomplished. The vagus nerve was found posterior to the CCA. No cerebral
infarction occurred postoperatively. He was discharged on the seventh postoperative
day without any complications.
Fig. 2 Case 2. Three-dimensional computed tomography arteriography + venography, lateral
view, revealed the left fenestrated internal jugular vein (IJV) (arrowhead) running
anteriorly to the common carotid artery (CCA) (A). The common facial vein (CFV) was found and dissected caudally and revealed the
IJV before carotid endarterectomy (B). After ligation and cutting of the CFV (C), the carotid sheath with the IJV turned laterally revealed the external carotid
artery, CCA, and internal carotid artery (D). PBDGM, posterior belly of digastric muscle.
Case 3
A 70-year-old man with dyslipidemia presented with a 1-week history of transient right
hemiparesis for 1 hour and was admitted for left carotid stenosis up to 50%. 3D CTA + V
revealed the IJV located slightly anterior to the CCA in the lateral view ([Fig. 3A]). Left CEA was performed. The CFV was found and dissected caudally and revealed
the IJV ([Fig. 3B]). After ligation and cutting of the CFV ([Fig. 3C]), the carotid sheath with the IJV turned laterally revealed the external carotid
artery, CCA, and internal carotid artery ([Fig. 3D]), and CEA was accomplished. The vagus nerve was found posterior to the CCA. No cerebral
infarction occurred postoperatively. He was discharged on the seventh postoperative
day without any complications.
Fig. 3 Case 3. Three-dimensional computed tomography arteriography + venography, lateral
view, revealed the left internal jugular vein (IJV) located slightly anterior to the
common carotid artery (CCA) (A). The common facial vein (CFV) was found and dissected caudally and revealed the
IJV (B). After ligation and cutting of the CFV (C), the carotid sheath with the IJV turned laterally revealed the external carotid
artery, CCA, and internal carotid artery (D). CEA, carotid endarterectomy; PBDGM, posterior belly of digastric muscle.
Discussion
Variations in the relationship between the IJV and CCA have been reported as the cause
of unsuccessful IJV cannulations.[7]
[9] Two-dimensional ultrasonographic examinations of the right and left supraclavicular
triangle in 219 adult individuals who had no history of neck surgery found an anterolateral
location of the IJV to CCA was the most common configuration observed on both sides
of the neck (84% right side and 91.8% left side), followed by the lateral (14.2% right
and 6.4% left) and anterior (1.4% right and 1.8% left) locations.[6] Another study found the IJV was in the lateral and anterolateral positions in 86.66%
of cases on the right and in 85% on the left.[10] Analysis of tomographic images identified an IJV medial of the CCA in 1.1% of cases.[11] We found a prevalence of 5.0% in our series, based on 3 of 60 neck dissections performed
by a single surgeon at our institution from 2020 to 2022.
We usually performed CEA with the following procedure. The carotid triangle of the
anterior cervical triangle is used as a landmark for the carotid arteries. The carotid
triangle consists of three muscles, the sternocleidomastoid muscle, the omohyoid muscle,
and the PBDGM. After skin incision, dissection is performed along to the anterior
border of the sternocleidomastoid muscle to find the omohyoid muscle, and reveal the
CCA in the carotid sheath at the lower corner of the carotid triangle. At this level,
the carotid sheath encloses the CCA, IJV, and vagus nerve, of which the CCA is located
anteromedial, the IJV posterolateral, and the vagus nerve posterior,[12] allowing the CCA to be secured without interference from the IJV or vagus nerve.
However, in the case of the IJV located in unusual positions, such as anterior or
medial to the CCA, the IJV is disturbed before reaching the CCA and may suffer injury.
Furthermore, since the CCA is located posteromedial to the jugular vein, dissection
behind the IJV may cause injury to the vagus nerve. The anatomical position of the
vagus nerve within the carotid sheath is usually posterior between the IJV and the
CCA (posterolateral to the CCA).[13]
[14] Variations of the course of the vagus nerve are thought to be rare.[14] In our three cases, the vagus nerve was located normally, posterior to the CCA.
On the other hand, recent reports have indicated that the vagus nerve course variations,
anterior or medial between the IJV and CCA in the carotid sheath, are not so rare[15]
[16] and can be found more often in the left side.[13] Therefore, dissection of the IJV from in front of or behind the IJV carries some
risk of affecting the vagus nerve. Since the vagus nerve does not exist in the carotid
sheath at the site of CFV inflow to the IJV, the carotid sheath can be safely dissected
by using this site as a guide to identify the IJV, enter the inside of the carotid
sheath, and reach the CCA medial to the IJV.
Therefore, it is necessary to know the relationship between the IJV and the CCA before
surgery. We also need to simulate how to reveal the CCA in the case of unusual course
of the IJV. Consequently, we consider that 3D CTA + V simulation before surgery is
useful.
In the case of unusual location of the IJV, we propose a different dissection method
to find the carotid arteries. Dissection of the retromandibular space can reach the
PBDGM. The CFV is located superficially at the anterior part of the PBDGM. No dangerous
structure prevents reaching the PBDGM. Because the CFV flows out to the IJV, the CFV
is considered a good landmark to find the IJV. After dissection and ligation of the
CFV, dissection is continued anterior border of the IJV to find the CCA. In this manner,
we have successfully performed CEA in three patients with unusual IJV location.
The posterior cervical triangle approach is an alternative approach, which is proposed
for high carotid artery exposure for CEA[17]
[18] in the case of unusual location of the IJV. This technique can reveal the CCA without
concern for the IJV, even if the IJV is located anterior to the CCA.
IJV anomaly such as bifurcation, duplication, fenestration, trifurcation, and posterior
tributary have also been reported.[4] Three prior studies have assessed the prevalence of duplicated or fenestrated anatomical
variations of the IJV. A prevalence of 3.3% was based on 4 cases of duplicated or
fenestrated IJVs among 123 neck dissections in a Japanese population.[19] A prevalence of 0.4% was based on 3 cases of duplicated or fenestrated IJVs among
approximately 750 neck dissections in France.[20] A prevalence of 1% was based on 3 cases of duplicated or fenestrated IJVs among
295 patients undergoing neck dissection in the United States.[21] IJV fenestration in our case 2 was identified preoperatively by 3D CTA + V. Whether
such venous malformations are related to IJV location abnormalities is unknown, so
our case 2 may have been an accidental complication, but more cases need to be accumulated
in the future.
Conclusion
We conclude that there is a wide variation in the anatomical location of the IJV to
the CCA and, because of this variation, routine techniques of CCA dissection may result
in complications of the IJV or vagal nerve injury. Therefore, we recommend 3D CTA + V
simulation to identify the IJV location before CEA.
