أ

The National Ribat University

Faculty of Graduate Studies and Scientific Research

Anatomical Variations of Internal Carotid Artery

among Sudanese people

A thesis Submitted in Partial Fulfillment Required for MSc in Clinical

Human Anatomy

By: Yousra ELtereifi Ahmed Kormino

Supervisor: Dr. Kamal Eldin Elbadawi Babiker

2017

I

بسم هللا الرحمن الرحيم

قال تعالى :

) لقد خلقنا االنسان في أحسن تقويم (

صدق هللا العظيم

(4)سورة التين :

II

Acknowledgement

Foremost, I would like to express my sincere gratitude to my

supervisor dr Kamal Eldin Elbadawi Babiker for his continuous support of

my study and research, patience, motivation, enthusiasm, and immense

knowledge. His guidance helped me in all the time of research and writing of

this thesis. I could not have imagined having a better advisor and mentor for

my study.

Besides my supervisor, I would like to thank the rest of my study

committee: Prof Tahir and Dr Yasir, for their encouragement, insightful

comments and hard questions.

My sincere thanks also goes to Dr Hayder, for always being there for

us.

I thank my colleagues, for the stimulating discussions, sleepless nights

we were working together before deadlines, and for all the fun we have had.

III

Dedication

Every challenging work needs self efforts as well as guidance of elders

especially those who were very close to our heart.

My humble effort I dedicate to my sweet, loving and supporting family

(mother, father, husband and little leen), whose affection, love,

encouragement and prays of day and night make me able to get such success .

Along with all hard working and respected professors.

IV

بحثمستخلص ال

:الخلفية

سباتي الداخلي و هما الشريان ال ساسيينأدموية للمخ على شريانين تعتمد التغذية ال

الذي يحدث بين تفرعاتهما )دائرة ويليس(. و التفاغر الشريان القاعدي

:األهداف

السباتي الداخلي لدى ختالفات التشريحية للشريانصممت الدراسة للتعرف على اإل

و نسبة كل منها. السودانيين

:المواد و الطرق

ددوا بالمرضى الذين تر صورة مقطعية محوسبة لألوعية الدموية الخاصة 40تم جمع

2015في الفترة من يناير السودان –بالخرطوم شعه بمستشفى رويال كير العالميهعلى قسم األ

ختالفات التشريحية و جرت دراسة اإل، لشريان السباتي الداخلي ا و التي توضح 2017الى مايو

.ين السوداني لدى للشريان السباتي الداخلي

:النتائج

ختالف تشريحي في الشريان ( لديهم إ%12.5أشخاص ) 5الدراسة أن هناك وجدت

واحدة حيث كانت جميع هذه الحاالت من النوع الذي لم منهم ذكور و أنثى 4داخلي؛ السباتي ال

( حاالت في الجهة اليمنى و حالة واحدة %10) 4يتكون فيه الشريان السباتي الداخلي و كانت

%( في الجهة اليسرى.2.5)

:المناقشة

الشريان السباتي الداخلي لدى ختالفات كثيرة في ال توجد إ مقارنة بالدراسات السابقة

5 في ذو نسبة كبيرة فقطو ما وجد لم يكن ختالفات إل, حيث لم تجد الدراسة كل انواع ادانيينالسو

%.12.5تمثل نسبة حاالت

:الخالصة

و ضئيلة لدى السودانيين يان السباتي الداخلي ختالفات تشريحية في الشرإن نسبة وجود إ

.نها تكون عديمة االعراض و تكتشف بالصدفةإن وجدت فإ

V

Abstract

Background:

The anatomical variations of the internal carotid artery may be a major

causes or contributing factors to many diseases due to its critical place of

supply and should be known to avoid and reduce the complications during

the invasive procedures. Sometimes these variations pass undiscovered and

just found on routine examination.

Objective:

To study the anatomical variations of internal carotid artery among

Sudanese.

Materials and methods:

40 (12 MRA, 28 CTA) images of subjects who were attended to the

Radiology Department at Royal Care International Hospital in Khartoum _

Sudan. The internal carotid artery was assesed for any anatomical variant.

Results:

The study found that only 5 subjects (12.5%) had anatomical variation

of agenesis type, 4 of them were males and 1 female.

Disscusion:

The anatomical variation of the ICA is uncommon and discovered

accidentally, as revealed by this study.

Conclusion:

Knowing the normal anatomy and the normal variations of the ICA is

so important for the clinicians and neurosurgeons in their practice to avoid

damage and massive bleeding during surgeries.

VI

List of abbreviations

ACA Anterior cerebral artery

CCA Common carotid artery

CRM Carotid rete mirabile

CT Computed tomography

CTA Computed tomography angiogram

ECA External carotid artery

ICA Internal carotid artery

ICAA Internal carotid artery agenesis

Lt Left

MRA Magnetic resonance angiogram

PCA Posterior carotid artery

Rt Right

3rd Third

VII

List of figures

Fig Title Page

4.1 Gender distribution 11

4.2 Age distribution 12

4.3 Abnormality type distribution 13

4.4 Right side agenesis of the ICA 14

4.5 Abnormality side distribution 15

4.6 Main collateral circulation distribution 16

4.7 Relation between gender and abnormality

type

17

4.8 Relation between abnormality type and side 18

VIII

List of tables

Table Title Page

4.1 Gender distribution 11

4.2 Age distribution 12

4.3 Abnormality type distribution 13

4.4 Abnormality side distribution 15

4.5 Main collateral circulation distribution 16

4.6 Relation between gender and abnormality

type

17

4.7 Relation between abnormality type and

side

18

IX

The contents

Title Page

Alayah I

Acknowledgment II

Dedication III

Abstract in Arabic IV

Abstract in English V

List of abbreviations VI

List of figures VII

List of tables VIII

The contents IX

Chapter One: Introduction and Objectives

1.1 Introduction 1

1.2 Justification 2

1.3 Objectives 2

1.3.1 General objective 2

1.3.2 Specific objectives 2

Chapter Two: Literature Review

2.1 Gross Anatomy 3

2.1.1 development of ICA 3

2.1.2 Course of ICA 3

2.1.3 Relations 4

2.1.4 Carotid sheath 4

2.1.5 Segments 5

2.1.6 Branches 6

2.2 Clinical considerations 6

2.3 Previous studies 6

Chapter Three: Materials and Methods

3.1 Study Design 9

3.2 Study Area 9

3.3 Study Duration 9

3.4 Study Population 9

3.4.1 Inclusion Criteria 9

3.4.2 Exclusion Criteria 9

3.5 Variables 9

3.6 Sampling 9

3.6.1 Sample type 9

3.6.2 Sample size 9

3.7 Data collection 10

3.7.1 Data collection tools 10

X

3.7.2 Data analysis 10

3.8 Data management 10

3.9 Ethical consideration 10

Chapter Four: Results

4.1 Results 11

Chapter Five: Discussion

5.1 Discussion 19

Chapter Six: Conclusion and Recommendations

6.1 Conclusion 20

6.2 Recommendations 21

Chapter Seven: References

7.1 References 22

Annex: Data Collection Sheet

Data collection sheet 24

Chapter One

Introduction and Objectives

1

1. Introduction and objectives

1.1 Introduction:

The internal carotid artery arise at the bifurcation of the common

carotid arteries at the level of the upper border of the lamina of the thyroid

cartilage ( upper border of C4 vertebra) or at higher level near the tip of the

greater horn of the hyoid bone (C3 vertebra).(1)

The internal carotid artery along with the vertebral system supply the

cerebral hemispheres and the wall of the diencephalon, they anastomose with

each other around the optic chiasma and infundibulum of the pituitary stalk

forming the arterial circle of Willis.(2)

This circle is formed in the following way; the basilar artery from the

vertebral system ,divides at the upper border of the pons into the right and left

posterior cerebral arteries, each one receives a small posterior communicating

artery that runs backwards through the interpeduncular cistern from the

internal carotid artery at the anterior perforated substance on the same side.

Each internal carotid artery gives off an anterior cerebral artery; the circle of

Willis is completed by the anterior communicating artery, a small vessel that

unites the anterior cerebrals in the chiasmatic cistern, below the rostrum of the

corpus callosum.(2)

Because of the importance of the places where they supply blood, the

variations of the internal carotid arteries should be known to avoid and reduce

the complications during the invasive procedures, these anatomical variations

include its origin, course, branches and even presence or absence of the artery

itself.

Therefore the aim of this study is to evaluate the incidence of these

anatomical variations of the internal carotid artery.

2

1.2 Justification:

The normal blood flow to the brain is important to keep its normal

functions, and this is maintained by the fluent blood flow within the arteries

and their anastomoses.

Any disturbance to this may lead to serious lesions and dysfunction to

that part of the brain supplied by the affected artery. This may be either due to

anatomic variations or a disease. No previous studies conducted in Sudan

concerning this topic.

1.3 Objectives:

1.3.1 General objective:

To study the anatomical variations of the internal carotid artery

among Sudanese population.

1.3.2 Specific objectives:

• To determine the presence of the anatomical variation of ICA.

• To determine the incidence of each anatomical variation of ICA.

• To determine the association between gender and each anatomical

variant of ICA.

Chapter Two

Literature Review

3

2. Literature review

2.1 Gross anatomy:

The ICA begins at the bifurcation of the common carotid artery at the

level of the upper border of the thyroid cartilage. It supplies the brain, the eye,

the forehead, and part of the nose. The artery ascends in the neck passing

through the carotid sheath with the internal jugular vein and vagus nerve. At

first it lies superficially; it then passes deep to the parotid salivary gland.(3)

The ICA leaves the neck by passing into the cranial cavity through the

carotid canal in the petrous part of the temporal bone. It then passes upward

and forward in the cavernous venous sinus (without communicating with it).

The artery then leaves the sinus and passes upward again medial to the

anterior clinoid process of the sphenoid bone. The ICA then inclines

backward, lateral to the optic chiasma, and terminates by dividing into the

anterior and the middle cerebral arteries.(3)

2.1.1 Development of ICA:

The ICA arises from the third arch artery and the dorsal aorta. These

two components unite, with a proximal process from the capillary network

that exists in the walls of the forebrain and midbrain. This union forms a

primitive ICA that is identified approximately by the fourth week. (12)

2.1.2 Course of ICA:

In the neck the ICA is lateral to the external carotid at its origin, but soon

passes up posteriorly to a medial and deeper level. It has no branches and

passes straight up in the carotid sheath, beside the pharynx to the carotid canal

in the base of the skull.(4)

4

In the skull The ICA curves upwards from the foramen lacerum to enter

the posterior part of the sinus and runs forwards within the sinus, deeply

grooving the body of the sphenoid and the base of its greater wing. The artery

then curves upwards again to pierce the roof of the sinus, medial to the

anterior clinoid process, and turns backwards. The artery is accompanied by a

plexus of postganglionic sympathetic fibres from the superior cervical

ganglion.(5)

The ICA emerges from the roof of the cavernous sinus medial to the

anterior clinoid process and curves immediately backwards, lying on the roof

of the sinus before curving upwards lateral to the optic chiasma. At the

anterior perforated substance it divides into its terminal branches. The curve

of the internal carotid artery in and above the cavernous sinus as seen in a

lateral carotid arteriogram (like a U on its side, opening backwards) is

commonly called the carotid siphon.(6)

2.1.3 Relations:

The ICA has very important relations, in the neck; anterolaterally:

below the digastric, lie the skin, the fascia, the anterior border of the

sternocleidomastoid, and the hypoglossal nerve. Above the digastric lie the

stylohyoid muscle, the stylopharyngeus muscle, the glossopharyngeal nerve,

the pharyngeal branch of the vagus, the parotid gland, and the external carotid

artery; posteriorly: the sympathetic trunk, the longus capitis muscle, and the

transverse processes of the upper three cervical vertebrae; medially: the

pharyngeal wall and the superior laryngeal nerve; laterally: the internal

jugular vein and the vagus nerve.(3)

2.1.4 Carotid sheath:

This is not a fascia in the sense of a demonstrable membranous layer,

but consists of a feltwork of areolar tissue that surrounds the common and

5

internal carotid arteries, internal jugular vein, vagus nerve and some deep

cervical lymph nodes. It is thin where it overlies the internal jugular vein,

allowing the vein to dilate during increased blood flow. The sheath is attached

to the base of the skull at the margins of the carotid canal and jugular fossa,

and is continued downwards along the vessels to blend with the adventitia of

the aortic arch. In front the lower part of the sheath fuses with the fascia on

the deep surface of the sternocleidomastoid. Where they lie alongside, the

sheath blends with the pretracheal fascia. Behind the carotid sheath there is a

minimum of loose areolar tissue between it and the prevertebral fascia; the

cervical sympathetic trunk lies here in front of the prevertebral fascia.(7)

2.1.5 Segments:

There are several classification systems of the ICA, the most recent of

which was described by Bouthillier et al in 1996. Their classification system

is used clinically by neurosurgeons, neuroradiologists and neurologists and

relies on the angiographic appearance of the vessel and histological

comparison rather than on the embryonic development, there are seven

segments of ICA described by Bouthillier classification: C1 cervical

segment, which extends from the carotid bifurcation to the skull base; C2

petrous segment,which courses through petrous temporal bone I the carotid

canal; C3 lacerum segment, which together with C2 comprise the petrous

portion; C4 cavernous segment,which ends at the roof of the cavernous sinus

(proximal dural ring); C5 clinoid segment, which lies beneath the anterior

clinoidal process and between the proximal and distal dural rings; C6

ophthalmic segment, which is the first subarachnoid segment; C7

communicating segment, C6 and C7 comprise the intradural or supraclinoidal

portion.(8)

6

2.1.6 Branches:

Except for the terminal segment (C7) the odd numbered segments

usually have no branches, whereas the even numbered segments (C2, C4, C6)

each have two branches; C1: none; C2: caroticotympanic and vidian arteries;

C3: none; C4: meningohypophyseal and inferolateral trunks; C5: none; C6:

ophthalmic and superior hypophyseal arteries; C7: posterior communicating,

anterior choroidal, anterior cerebral, middle cerebral arteries. (9)

2.2 Clinical considerations:

Congenital anomaly of the carotid artery is a rare abnormality. It is

usually discovered incidentally by color Doppler carotid sonography,

angiography CT or MRI of the head and neck taken for some other reasons.

Most patients are not symptomatic because of sufficient cerebral circulation

supplied to the defective area by the communicating arteries of the circle of

Willis, intercavernous anastomoses, communicating arteries from external

carotid artery and by persistent embryologic arteries to the carotid artery

territory. However, sometimes, this anatomic variation may eventually lead to

some clinical signs and symptoms in particular circumstances in the head and

neck of which surgeons are unaware.These variations include congenital

absence; hypoplasia; rete mirabele; retropharyngeal; agenesis.

2.3 Previous studies:

In a study done by Tasar M, et al which studied five thousand one

hundred cerebral MRI and/or catheter angiograms performed between

February 1988 and March 2002, were reviewed for carotid artery abnormality,

and the results were seven (0.13%) patients with congenital absence or

hypoplasia ;4 (0.07%) of these patients were presented with hypoplasia of

ICA, 3 (0.05%) with absence of ICA were identified. The radiologic and

7

clinical study of 5 patients with unilateral (3 of these patients were presented

with hypoplasia and 2 with absence of ICA) and 2 patients with bilateral (one

was presented with absence of ICA, whereas the other was hypoplastic). The

congenital abnormality with absence or hypoplasia of ICA demonstrated that

those patients were asymptomatic and diagnosed incidentally.(10)

In another study done by Tode in which he reported the first case of

ICA agenesis in 1787, which was accidentally encountered after a cadaveric

dissection. The prevalence of congenital absence of ICA was estimated as

0.01%. The prevalence of absence of ICA was 0.058% and that of hypoplasia

of ICA was 0.079% in his series. Unilateral absence or hypoplasia of ICA

was more frequent on the left and bilateral absence or hypoplasia were more

exceptional and reported to be less than 10% of unilateral involvement.(10)

In a study done by Fuwa I, he found that the carotid rete mirabile

(CRM) was a very rare pathological condition; only six cases have been

reported in the English and Japanese literature. All previously reported case

subjects were adults with an age of 39 years. To his knowledge, this was the

first patient who presented with symptoms of CRM in childhood. CRM is a

physiological network between the external carotid and internal carotid

systems in lower mammals. Very rarely, these arterial channels were observed

in humans.(11)

Another study done by Lee et al in 1992, reviewed nine patients with

ICA aplasia. Of these, three patients had subarachnoid hemorrhages as the

presenting syndrome, three others had ischemic syndromes, one presented

with recurrent headache, and two were incidentally diagnosed by

angiography.(12)

Also in a study done by Handa et al, in 1980, they reported a case of

unilateral ICA agenesis in a 52-year-old female that presented with a

subarachnoid hemorrhage.(12)

8

A case reported by Mousa A Y and A F Aburahma, outlined an

unusual anatomic variant which was a retropharyngeal ICA and raised certain

considerations among clinicians during perioperative planning.(13)

Although the majority of retropharyngeal carotids are asymptomatic,

when symptoms occur, different presentations may be encountered, such as

submucosal pulsating masses in the posterior pharyngeal wall. It is also

important to recognize other possible presentations of this rare anomaly, such

as dysphagia, cervical bolus sensation, and even glossopharyngeal neuralgia.

In addition, extreme degrees of medialization of the carotid arteries may result

in progressive symptoms, including hoarseness and upper respiratory distress,

and the risk of the spread of infection in the oropharyngeal area. Erosion of

the oropharyngeal mucosa, perhaps from a nasogastric tube or during

tonsillectomy with or without adenoidectomy, may precipitate bleeding.(13)

A case study by Fons C et al, reported a 7-year old boy with right

miosis, mild blepharoptosis and iris hypopigmentation detected in a

routine pediatric follow-up without ipsilateral facial anhydrosis, flushing

or pain. There was no history of birth trauma and test with cocaine

provoked, no response of the right pupil, suggesting right Horner’s

syndrome. Mediastinal tumor was ruled out and brain MRI incidentally

showed absence of flow in the right internal carotid artery. Subsequent

MRA demonstrated agenesis of the right internal carotid artery without

other vascular - associated malformations. The final diagnosis was right

congenital Horner’s syndrome due to ipsilateral internal carotid agenesis.

(14)

Chapter Three

Materials and Methods

9

3. Materials and Methods

3.1 Study design:

This is an observational descriptive cross-sectional study.

3.2 Study area:

The study was conducted at Royal Care International Hospital,

Department of Radiology, Khartoum state, Sudan.

3.3 Study duration:

The study was held during the period between (Jan 2015 _ May 2017).

3.4 Study population:

All individuals underwent CTA or MRA for ICA in Khartoum state

(Royal Care International Hospital, Radiology Department).

3.4.1 Inclusion Criteria:

All individuals underwent CTA or MRA for ICA in Khartoum state

(Royal care international hospital) with normal ICA.

3.4.2 Exclusion criteria:

All patients with history of ICA (occlusion or stenosis).

3.5 Study variables:

Age, gender, abnormality type of ICA, abnormality side of ICA.

3.6 Sampling:

3.6.1 Sample type:

The sample group of this study was selected randomly among Sudanese

population.

3.6.2 Sample size:

40 subjects (28 CTA and 12 MRA).

3.7 Data collection:

3.7.1 Data collection tools:

Data collected was CTA and MRA by data collection sheet.

10

3.7.2 Data analysis:

Data analyzed by SPSS (Social Package for Statically Science), version

24, 2016.

3.8 Data management:

Data was analyzed as mentioned above and then it was presented and

described by using the pie, tables, charts and figures.

3.9 Ethical consideration:

• Confidentiality of name or personal data was considered.

• Approval statement was considered from institutional authorities.

• Ethical Committee approval was taken.

Chapter Four

Results

11

4. Results

A total of 40 individuals were examined, 29 of them underwent CTA and

11 underwent MRA, twenty-four of them were males (60%) and sixteen

(40%) were females. As shown in Table (4.1) and fig (4.1).

Table (4.1): Distribution of gender.

Gender Frequency Percent

Male 24 60%

Female 16 40%

Total 40 100%

Fig (4.1): Represents gender distribution.

0%

10%

20%

30%

40%

50%

60%

70%

Male Female

60%

40%

Gender

Per

cen

tage

12

The age of subjects was arranged into seven groups ranged from (0

_>70) yrs, as shown in table (4.2) and fig (4.2).

Table (4.2): Age group distribution among individuals.

Age group/yrs Frequency Percent

0 - 20 4 10%

21 - 30 4 10%

31 - 40 5 12.5%

41 - 50 9 22.5%

51 - 60 7 17.5%

61 - 70 6 15%

> 71 5 12.5 %

Total 40 100%

Fig (4.2): Represents age distribution.

0%

5%

10%

15%

20%

25%

20-0 30-21 40-31 50-41 60-51 <71

10% 10%12.50%

22.50%

17.50%

12.50%

Age groups

Per

cen

tage

13

The study found that 5 (12.5%) individuals had agenesis type, while the

remaining 35(87.5%) individuals were normal, as shown in table (4.3) and fig

(4.3, 4.4).

Table (4.3): Abnormality type distribution.

Abnormality type Frequency Percent

Hypoplastic 0 0%

Agenesis 5 12.5%

None 35 87.5%

Total 40 100%

Fig (4.3): Represents abnormality type distribution.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Hypoplasia Agenesis None

0

12.5%

87.5%

Per

cen

tage

Abnormality type of ICA

14

Fig (4.4): MRA image shows the right side agenesis of the ICA (the arrow

shows the left side ICA).

The abnormality was found in 4 (10%) cases in the right side, 1 (2.5%)

case in the left side, while the remaining 35(87.5%) cases were normal, as

shown in table (4.4) and fig (4.5).

15

Table (4.4): Shows the abnormality side distribution

Abnormality side Frequency Percent

Right 4 10%

left 1 2.5%

None 35 87.5%

Total 40 100%

Fig (4.5): Shows the abnormality side distribution

Concerning the main collateral circulation the study showed that 2

(5%) of the cases originated from the ACA, while 3 (7.5%) cases from

the PCA and the remaining subjects were normal, as shown in table (4.5)

and fig (4.6).

10%2.5%

87.5%

Right

Left

None

Abnormality side of ICA

16

Table (4.5): Shows the main collateral circulation distribution

Main collateral circulation Frequency Percent

ACA 2 5%

PCA 3 7.5%

Fetal type 0 0%

Adult type 0 0%

Third type 0 0%

None 35 87.5%

Total 40 100%

Fig (4.6): Shows the main collateral circulation distribution

In comparing the abnormality type with the gender, the study revealed

that the agenesis type was found in 1 (2.5%) female and 4 (10%) males

while the hypoplastic type wasn't found in any case; as shown in table

(4.6) and fig (4.7).

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

ACA PCA Fetal type Adult type Third type None

5% 7.5%0% 0% 0%

87.5%

Collateral circulation of ICA

per

cen

tage

17

Table (4.6): Shows the relation between the gender and abnormality

type

Fig (4.7): Shows the relation between gender and abnormality type.

In comparing between the abnormality type and the abnormality side it

was observed that 4 (10%) cases were in the right side and 1 (2.5%) case was

in the left side; as shown in table (4.7) and fig (4.8).

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Agenesis Hypoplasia

10%

0%2.5% 0%

Males

Females

Abnormality type

Per

cen

tage

Variations

Gender

Agenesis Hypoplasia

Frequency Percent Frequency Percent

Male 4 10% 0 0%

Female 1 2.5% 0 0%

18

Table (4.7): Shows the relation between the abnormality type and

side.

Fig (4.8): Shows the relation between abnormality type and side.

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

10%

Agenesis Hypoplasia

10%

0

2.5%

0

Right

Left

Abnormality type

Per

cen

tage

Variations

Abnormality

type

Right Left

Frequency Percent Frequency Percent

Agenesis 4 10% 1 2.5%

Chapter Five

Discussion

19

5. Discussion

The present study focused on two main types of the anatomical

variations of the ICA; agenesis and hypoplasia.

Among the 40 cases studied, there were only 5 (12.5%) cases were

found to have an anatomical variant; the agenesis type, which was distributed

as follows: 4 (10%) cases in the right side and 1 (2.5%) case on the left side

which disagree with what mentioned in the literature in the study done by

Luis F. Gonzalez-Cuyar.

As observed in this study, 4 (10%) cases were males and 1 (2.5%) case

was female which agree with what mentioned by Mustafa Tasar.

These 5 cases were found in different age groups; one of them was

found in a 6 yrs old child, which agree with a case reported in the literature by

Fons et al, i.e it should be expected in any age.

All the cases found in this study encountered unilateral agenesis of

ICA with a rate of 12.5% in contrast with what mentioned in the literature by

Fons et al, who reported a rate of 0.36%. All these cases were asymptomatic

and discovered incidentally as mentioned in the literature by Mustafa Tasar.

The hypoplastic type wasn't found in any case under the study (0%)

which coincide with what mentioned in literature as it is a rare congenital

anomaly.

In comparing this study with previous studies done in other countries,

the results obtained here are almost of the same value; in the study done by

Tasar M, et al the congenital absence or agenesis of the ICA in the subjects

under study were asymptomatic and discovered incidentally, because they got

their blood supply from the developed collateral circulations as mentioned in

the literature by Mustafa Tasar.

20

The main collateral circulation of 2 (5%) cases is from the ACA, while

3 (7.5%) cases from the PCA and the remaining cases were normal which

agree with the study done by Tasar M.

The other types of collateral circulation (fetal, adult and third types)

were not found in the present study.

Chapter Six

Conclusions and Recommendations

21

6. Conclusions and Recommendations

6.1 Conclusions:

This study showed that the anatomical variations of the ICA were

present in some cases but not as common as anywhere else and to be

considered in mind while performing any surgery involving this area, and to

be kept in mind that these cases were discovered incidentally.

The study stated that the more common anatomical variant of the ICA

in the Sudanese subjects was the agenesis type.

Also the study concluded that the agenesis type of congenital anomaly

was common in males, and was found in the right side than the left one.

The study remarks that the collateral circulation usually originates from

the PCA, then followed by the ACA.

The subjects were of different age groups; one of them was 6 yrs old

child, so it means that it is not related to specific age.

22

6.2 Recommendations:

The study recommends the followings:-

• All surgical procedures involving the area of the ICA must be preceded

by CTA or MRA.

• The neurosurgeons and neurologists should know about these

anatomical variations of the ICA.

• Another study should be done in the future to shed more light on the

anatomical variations of the ICA by studying a large number of cases.

Chapter Seven

References

23

7. References

1-Chummy S Sinnatamby. Head and Neck and Spine. In: Chummy S

Sinnatamby (ed). Last's anatomy 12th edition. Edinburgh: Churchill

Livingstone Elsevier; 2011; p.342.

2-Chummy S Sinnatamby. Central nervous system. In: Chummy S

Sinnatamby (ed). Last's anatomy12th edition . Edinburgh: Churchill

Livingstone Elsevier; 2011; p.471.

3-Richard S. Snell. Head and Neck. In: Richard S Snell (ed). Clinical anatomy

by regions 8th edition. Philadelphia. Lippincott; 2008; p.750.

4-Chummy S Sinnatamby. Head and Neck and Spine. In: Chummy S

Sinnatamby (ed). Last's anatomy 12th edition. Edinburgh: Churchill

Livingstone Elsevier; 2011; p.343.

5-Chummy S Sinnatamby. Head and Neck and Spine. In: Chummy S

Sinnatamby (ed). Last's anatomy 12th edition. Edinburgh: Churchill

Livingstone Elsevier; 2011; p.447.

6-Chummy S Sinnatamby. Head and Neck and Spine. In: Chummy S

Sinnatamby (ed). Last's anatomy 12th edition. Edinburgh: Churchill

Livingstone Elsevier; 2011; p.449.

7-Chummy S Sinnatamby. Head and Neck and Spine. In: Chummy S

Sinnatamby (ed). Last's anatomy 12th edition. Edinburgh: Churchill

Livingstone Elsevier; 2011.

8-Segments of the ICA were found in: http//rhoton.ineurodb.org/?page=22507

9-Branches of the ICA were found in:

http://radiopaedia.org/articles/internal-carotid-artery-1

10-Tasar M, et al. Congenital absence or hypoplasia of the carotid artery:

radioclinical issues. Am J Otolaryngol, 2004; 25 (5): p. 339-49.

11-Fuwa I. A pediatric case of carotid rete mirabile. Stroke, 1994; 25 (6): p.

1268-70.

12-Gonzalez-Cuyar LF, et al. Bilateral internal carotid absence: a case report

of a rare congenital anomaly. Cardiovasc Pathol, 2008; 17 (2): p. 113-6.

24

13-Mousa AY and AF AbuRahma. Retropharyngeal internal carotid artery: a

rare presentation with significant clinical implications. Ann Vasc Surg, 2013;

27 (8): p. 1189.

14-Fons C, et al. Agenesis of internal carotid artery in a child with ipsilateral

Horner's syndrome. J Child Neurol, 2009; 24 (1): p. 101-4.

25

The National Ribat University

Faculty of Graduate Studies and Scientific Research

Anatomical Variation of Internal Carotid Artery among

Sudanese people attending to the Radiology Department, Royal

Care International Hospital, Khartoum Sudan

Data collection sheet

Index number

Name …………………………………………………………………

Age......................years

Sex Male Female

Abnormality side: Rt Lt

Abnormality type : Hypoplastic Agenesis

Main collateral circulation: ACA PCA Fetal type

Adult Third type

Associated abnormality:

…………………………………………………...................................

…………………………………………………………………………

Symptoms (main features):

…………………………………………………………………………

Note:

…………………………………………………………………………