The paper aims to present a review of the CS tumors from the perspective of the specific MRI features of each entity, exemplified by our case collection. Knowledge of the structures' location within the CS and imaging characteristics can lead to a precise diagnosis.
a) Definition of the CS: Paired, tubular spaces surrounded by the carotid sheath that contains carotid arteries, internal jugular veins, cranial nerves (CN) 9-12 and sympathetic chain (Fig. 1) [1].
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/882886?maxheight=300&maxwidth=300)
Fig. 1: Lateral graphic of the neck depicting the carotid space (CS) as a tube extending from skull base to the aortic arch. The hyoid bone divides the CS into suprahyoid (SHN) and infrahyoid (IHN) portion. VS – visceral space, PVS – perivertebral space, SL-DCF - supeficial layer of deep cervical fascia.
References: Medvedev Olga; adapted from [1]
b) Anatomy of the CS [1,2,3] (Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9):
- superior: skull base (jugular and carotid foramen),
- inferior: aortic arch
SHN CS:
- medial: retropharyngeal space (RPS),
- lateral: parotid space (PS),
- anterior: parapharyngeal space (PPS),
- posterior: perivertebral space (PVS)
IHN CS:
- medial: visceral space (VS) and RPS,
- lateral: posterior cervical space (PCS),
- anterior: anterior cervical space (ACS),
- posterior: PVS
- SHN CS: internal carotid artery (ICA), internal jugular vein (IJV), CN 9-12, sympathetic plexus, level II internal jugular lymph nodes (LNs) closely associated to CS surface;
- IHN CS: CN10, common carotid artery (CCA), IJV, level III and IV LNs closely associated;
- Fascia: carotid sheath composed of all 3 layers of deep cervical fascia (DCF), which is poor-defined in the SHN and well-defined in IHN.
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/882951?maxheight=300&maxwidth=300)
Fig. 2: Axial graphic of the SHN at the level of C1 vertebral body. MS – masticator space, PMS – pharyngeal mucosal space, RPS – retropharyngeal space, PPS – parapharyngeal space, PS – parotid space, CS – carotid space, PVS – perivertebral space, ICA – internal carotid artery, IJV – internal jugular vein, SL-, ML-, DL-DCF – superficial, middle, deep layer of deep cervical fascia
References: Medvedev Olga; adapted from [1]
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/882952?maxheight=300&maxwidth=300)
Fig. 3: Graphic illustration of magnified left SHN CS. The carotid artery lies in the center and the jugular vein is posterolateral to it; CN 10 is in the posterior groove between the two vessels; CN 9, 11, 12; the ansa cervicalis is embedded in the anterior carotid sheath; the sympathetic plexus is found posteriorly. The carotid sheath is made up of all 3 layers of deep cervical fascia and is less substantial than in the IHN.
ICA - internal carotid artery, IJV - internal jugular vein; SL-, ML-, DL-DCF - superficial, middle, deep layer of deep cervical fascia
References: Medvedev Olga; adapted from [1]
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/882953?maxheight=300&maxwidth=300)
Fig. 4: Axial T2 image at the level of C1 vertebral body. The SHN CS contains the internal carotid artery, internal jugular vein and CN9-12. CS is posterior to the styloid process (better seen on CT). At this level a CS mass will displace the parapharyngeal space anteriorly and the styloid process anterolaterally.
References: Emergency County Hospital Cluj – Napoca, Romania
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/883004?maxheight=300&maxwidth=300)
Fig. 5: Axial T2 image at the level of mid-oropharynx. The posterior belly of the digastric muscle is visible anterolateral to the CS. A CS mass here would push this muscle anterolaterally and the parapharyngeal space anteriorly.
References: Emergency County Hospital Cluj – Napoca, Romania
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/883005?maxheight=300&maxwidth=300)
Fig. 6: Axial T2 image at the level of hyoid bone. At this level the carotid bifurcation can be seen and only the vagus nerve is left within the CS.
References: Emergency County Hospital Cluj – Napoca, Romania
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/883006?maxheight=300&maxwidth=300)
Fig. 7: Axial graphic of the CS in the IHN. The carotid sheath contains all 3 layers of deep cervical fascia. SL-, ML-, DL-DCF – superficial, middle, deep layer of deep cervical fascia; VS – visceral space; ACS – anterior cervical space, PCS – posterior cervical space, RPS – retropharyngeal space; PVS – perivertebral space; CCA – common carotid artery; IJV – internal jugular vein.
References: Medvedev Olga; adapted from [1]
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/883019?maxheight=300&maxwidth=300)
Fig. 8: Graphic illustration of magnified left IHN CS. Note that at this level the CS contains the common carotid artery (CCA), internal jugular vein (IJV) and only the vagus cranial nerve (CN10). SL-, ML-, DL-DCF – superficial, middle and deep layer of deep cervical fascia
References: Medvedev Olga, magnified from fig. 7
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/883020?maxheight=300&maxwidth=300)
Fig. 9: Axial T2 image at the level of cricoid cartilage. Surrounding tissue relationships can be seen: posterolateral – fat filled posterior cervical space, posteromedial – perivertebral space, medial – visceral and retropharyngeal space, anterior – sternocleidomastoid muscle. At this level the CS contains the common carotid artery, internal jugular vein and vagus nerve. A mass here may encompass the common carotid artery and internal jugular vein or push them apart.
References: Emergency County Hospital Cluj – Napoca, Romania
c) Tumoral processes that can occur within CS are summarized in Table 1.
As regarding the incidence frequency [4] and the clinical implications [2] one can divide these pathologies as represented in Table 2.
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/883054?maxheight=300&maxwidth=300)
Table 1: Tumoral processes that can occur within the carotid space. CN – cranial nerves; HIV - Human immunodeficiency virus; NHL – Non-Hodgkin Lymphoma; HL - Hodgkin Lymphoma.
References: adapted from [1]
![](https://epos.myesr.org/posterimage/esr/ecr2020/156142/media/883055?maxheight=300&maxwidth=300)
Table 2: Incidence frequency of CS masses (adapted according to [1, 4]) and examples of clinical implications of CS masses (adapted according to [1]). SCCa - Squamous cell carcinoma; CN – cranial nerves; CA- carotid artery; IJV – internal jugular vein.
References: adapted according to [1, 4]