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Study of Thyroidea Ima Artery: Narrative Review of Its Prevalence and Clinical Significance

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Thyroidea ima artery shows variability in origin and course with infrequent occurrence. Most frequently it originates from the brachiocephalic, followed by the aortic arch, common carotid, internal thoracic, inferior thyroid, transverse scapular, and suprascapular arteries. Clinically Thyroidea ima artery is very important for vascular surgeons. Hence the study was carried out. Aim of the study is to describe incidence, origin, course and clinical significance of this artery. Literature was explored using various databases. Only English language articles were selected for the study. Various terms related to thyroid ima artery were used for searching the literature. The detailed knowledge of origin and course of this artery is very essential to clinicians and vascular surgeons as it may be injured during surgery in the superior mediastinum or lower neck as in a low tracheostomy as during these procedures the artery may be damaged causing fatal haemorrhage. Its presence may be misinterpreted in neck angiography.
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Basic Sciences of Medicine 2022, 11(1): 1-4
DOI: 10.5923/j.medicine.20221101.01
Study of Thyroidea Ima Artery: Narrative Review of
Its Prevalence and Clinical Significance
Rajani Singh
Department of Anatomy, UP University of Medical Sciences, Saifai, Etawah, India
Abstract Thyroidea ima artery shows variability in origin and course with infrequent occurrence. Most frequently it
originates from the brachiocephalic, followed by the aortic arch, common carotid, internal thoracic, inferior thyroid,
transverse scapular, and suprascapular arteries. Clinically Thyroidea ima artery is very important for vascular surgeons.
Hence the study was carried out. Aim of the study is to describe incidence, origin, course and clinical significance of this
artery. Literature was explored using various databases. Only English language articles were selected for the study. Various
terms related to thyroid ima artery were used for searching the literature. The detailed knowledge of origin and course of this
artery is very essential to clinicians and vascular surgeons as it may be injured during surgery in the superior mediastinum or
lower neck as in a low tracheostomy as during these procedures the artery may be damaged causing fatal haemorrhage. Its
presence may be misinterpreted in neck angiography.
Keywords Thyroidea ima artery, Arch of aorta, Neck, Superior mediastinum
1. Introduction
Thyroid gland consists of right and left lobes connected by
isthmus. Mostly these lobes including isthmus are irrigated
by superior and inferior thyroid arteries (Figure 1),
originating from the external carotid artery and thyrocervical
trunk, respectively [1]. During head and neck surgeries such
as hemi-/total thyroidectomies and parathyroidectomies,
these arteries serve as landmarks for recurrent laryngeal
nerve (Figure 1), hence their recognition is very important
[2]. Moreover, these arteries are ligated during
aforementioned procedures to ameliorate patient outcome
[3]. Existence of additional third artery, Thyroidea ima artery
may creat complications due to its unforeseeable origin,
course, morphology and rarity [4,5].
The thyroidea ima has been observed in 3% of individuals
on average. It irrigates thyroid gland in general and isthmus
in particular when present. Thyroidea ima artery sometimes
also supply the trachea, oesophagus, parathyroid glands and
thymus. The thyroidea ima artery was first elucidated in
1772 by Neubauer hence also known as thyroidea ima artery
of Neubauer or Neubauer’s artery.
It is also called the accessory thyroid artery, thyroid artery
of Neubauer, and lowest thyroid artery [6,7]. This artery has
been found highly variable in respect of origin and course
with inconstant occurrence. As to origin is concerned,
* Corresponding author:
nani_sahayal@rediffmail.com (Rajani Singh)
Received: Jul. 5, 2022; Accepted: Jul. 18, 2022; Published: Jul. 20, 2022
Published online at http://journal.sapub.org/medicine
Gruber examined 90 cases [8] and found that most
frequently it originates from the brachiocephalic (innominate)
artery, followed by the aortic arch, common carotid,
internal thoracic, inferior thyroid, transverse scapular,
and suprascapular arteries (Figure 2). Sometimes, when
thyroidea ima arteries is present, the inferior thyroid artery
is hypoplastic or absent. Thus, inferior thyroid artery is
supplemented or replaced by thyroidea ima artery [9]. As this
artery has diverse origin and course, it is prone to injury
causing life threatening hemmorahage while treating neck
pathology, during surgery in the superior mediastinum or
lower neck as in a low tracheotomy.
STA- superior thyroid artery, ITA- inferior thyroid artery, TG- thyroid gland,
SA-subclavian artery, AA- arch of aorta
Figure 1. Showing normal arterial supply of thyroid gland (A) anterior
view (B) posterior view (C) Lateral view
If unknown of variations of this artery specially if inferior
thyroid artery is also absent, it may lead to partial ischemia of
2 Rajani Singh: Study of Thyroidea Ima Artery: Narrative Review of Its Prevalence and Clinical Significance
thyroid and parathyroid gland leading to thyroid and
parathyroid related diseases. Hence, normal and variant
anatomy of Thyroidea ima artery is very essential. Hence the
study was carried out. The aim of the study is to consolidate
the anatomic variations of this artery and to bring out
associated clinical significance for ready reference to
vascular surgeons.
STA- superior thyroid artery, ITA- inferior thyroid artery, AA- arch of aorta,
BT- brachiocephalic trunk, TDA- thyroidea ima artery
Figure 2. Showing most common variant origin of thyroidea ima artery
from (A) Brachiocephalic trunk (B) Arch of aorta (C) Right common carotid
artery
2. Material and Methods
Literature was explored using different data bases like
scielo, pubmed, medline, wilyonline library, medline, google
scholar and terms such as thyroidea ima artery, prevalence of
thyroroidea ima artery, variations of thyroidea ima artery,
significance of thyroidea ima artery etc, related to thyroidea
ima artery and its clinical significance were used during
literature survey. Thyroidea ima artery in literature is not
differentiated from accessory thyroid artery irrigating lobes
of thyroid gland. In this study we classify this artery into two
groups: I- Accessory thyroid artery supplying thyroid gland,
II- thyroidea ima artery supplying isthmus of thyroid gland
and other viscera of neck. English language articles and
standard text books of Anatomy were selected for this study.
3. Results and Discussion
Thyroidea ima artery has diverse variation of origin such
as arch of aorta, brachiocephalic trunk, common carotid
arteries etc. The artery ascends anterior to trachea and
traverses the superior mediastinum and neck to reach the
thyroid [10].
Review of literature shows marked degree of variability in
the frequency, site of origin and the size of thyroidea ima
artery. The commonest site of origin of the thyroid ima artery
is from the brachiocephalic trunk in 1.9 to 6% cases followed
by right common carotid artery [8] in 1.4% to 1.7% and from
the arch of aorta on left side [11] in 0.36%. Bilateral
thyroidea ima arteries have been reported by Gruber.
Incidence of occurrence of this artery has been reported
ranging between 4%-10% in reference book describing
anatomic variations [9]. But Adachi detected in only 0.4% of
the population [12]. Some investigators have described its
frequency [13] as 6% or ranging [14] from 1.5% to 12.2%.
The calibre of thyroid ima artery may be as large as the
inferior thyroid artery or merely a minor branch. Thyroidea
ima artery has mean diameter of 3-5 mm.
Clinical Significance related to thyroidea ima artery:
If this artery originating from high pressure large artery
like arch of aorta, brachiocephalic trunk or common
carotid artery, is injured, there may be fatal hemorrage if
immediately hemostatis is not carried out [15]. This can be
avoided if surgeon is aware of variant origin and course
of Thyroidea ima artery. Moreover, if this artery is torned,
its caudal separated part may retract into the superior
mediastinum causing collection of blood clots in the thoracic
cavity which are difficult to remove [16,17]. The artery
is closely related to trachea, it may be damaged during
cricoidectomies and tracheostomies [18,19]. Prompt
hemostatis and vascular repair can improve the outcome of
patient [20] which is possible only if surgeon is aware of
variations in origin and course of thyroidea ima artery.
Abnormal ramification of artery can cause intraoperative
bleeding and /or post operative hematoma by damaging the
thyroid ima artery [21].
Thus, knowledge of the course of the thyroid ima artery is
important for surgeons while performing neck surgeries or
during tracheostomy procedures [22]. The knowledge of this
artery is necessary in angiography done as a preoperative
requisite in the thyroid and parathyroid surgeries, which
could be missed if this artery is not selectively injected.
Though the Thyoidea Ima artery, if present, is identifiable
on radiological studies, its iatrogenic damage associated
with emergent or surgical procedures can have acute and
long-term complications [23] if unaware of variant course of
the artery. With its course and relation to the thyroid, the
information about Thyroidea ima artery is an important for
various medical specialties, such as emergency medicine,
endocrinology, otolaryngology, and radiology [18,23].
Occasionally thymic branches from thyroidea ima artery to
supply thymus gland and oesophageal branches to supply
cervical part of the esophagus [13]. The thyroidea ima is
also reported to irrigate the inferior part of the thyroid
gland [24], the isthmus [25], or the gland in general [26]. If
thyroidea ima artery is only source of supply to thymus and
oesophagus then damage to this artery may cause ischemia to
these organs causing helm of complication if unaware of this
variation related to thyroidea ima artery.
Three cases have been reported in literature; in one case
the thyroidea ima artery was the only arterial supply to
thyroid and parathyroid glands, and in two instances it was
part of a dual arterial supply. If Thyroidea Ima artery is only
supply to thyroid and parathyroid glands and if it is damaged
inadvertently in absence of knowledge of variant origin and
Basic Sciences of Medicine 2022, 11(1): 1-4 3
course of this artery, it may cause preoperative fatal
haemorrhage and postoperative thyroid and parathyroid
related diseases. It can also supply enlarged parathyroid
glands, as illustrated in three cases. During treatment of
enlarged parathyroid glands, again the artery may be
damaged if unknown of this variation.
If thyroidea ima artery originates from large vessel
specially arch of aorta, a high pressure vessel, high pressure
will be generated in thyroidea ima artery making it prone
for aneurysm and dissection. Moreover, hemodynamic
changes and high endothelial shear stress/pressure will
modulate endothelial gene expression through complex
mechanotransduction processes, leading to the formation
of early atherosclerotic plaques [27,28] in thyroidea ima
artery. This is because the levels of endothelial vasoactive
agents such as nitric oxide synthase, endothelin-1, and
angiotensin-converting enzyme are significantly increased
due to alteration in endothelial shear stress and
hemodynamics [29]. These factors promote the deposition
of atherosclerosis in thyroidea ima artery. This is life
threatening when the artery is only supply to thyroid,
parathyroid, thymus, trachea or oesophagus. Carotid artery
stent is very common now a days. Thyroidea ima artery
if originating from carotid artery may be injured if
endovascular interventionist is unaware of this variant origin
leading to complications during the procedure [30].
The presence of thyroidea ima artery should be confirmed
if routine arteriography is negative, especially if the inferior
thyroid arteries are small or absent, or if a portion of the
expected thyroid stain is missing [31] or the thyroid gland
may suffer from ischemia if this artery is injured during neck
surgery.
4. Conclusions
Due to high variability in origin and course of thyroidea
ima artery, it may be damaged in neck surgeries,
tracheostomy procedures, endovascular interventions
causing intraoperative and postoperative haemorrhage.
In addition to this it may be misinterpreted in neck
angiography. Thus, detailed knowledge of this artery is of
paramount importance to neck surgeons, endocrinologists,
otolaryngologists, diagnostic radiologists, endovascular
interventionists, vascular surgeons and anatomists.
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