Maxillofacial

Sinus Disease

Unlocking Sinus Secrets - Radiological Insights.pdf

Unlocking Sinus Secrets - Radiological Insights

rPosters from Radiopaedia 2023 (July 24-28)

The paranasal sinuses are a group of four paired air-filled spaces that surround the nasal cavity. They are named after the facial and cranial bones in which they are located: the frontal, ethmoidal, sphenoidal, and maxillary sinuses.

The paranasal sinuses have several functions, such as humidifying and warming the inhaled air, enhancing the resonance of the voice, decreasing the weight of the head, and participating in the immune defense of the respiratory tract

maxillary sinus

sphenoid sinus

The sphenoid sinuses are paired spaces . The two hemisinuses are separated by a septum which may or may not be in the midline.

Radiopaedia

ethmoid sinus
They are separated into anterior and posterior groups by the basal lamella, the lateral attachment of the middle turbinate to the lamina papyracea.
Radiopaedia

frontal sinus
The frontal sinus has two chambers, one on each side, and they are almost always asymmetrical and separated by a septum.
Radiopaedia

Frontal, Anterior Ethmoid & Maxillary Sinuses

Frontal Sinus: Frontal Sinus Drainage Pathway ➡Hiatus Semiluniaris ➡Middle Meatus

The frontal sinuses are situated within the frontal bones, above the eyes and behind the eyebrows.

They are usually triangular-shaped and separated by a bony septum. The frontal sinuses drain into the middle nasal meatus via the frontonasal duct and the ethmoidal infundibulum.

Frontal infundibulum
Frontal Ostium
Frontal Recess

The Egyptian Journal of Radiology and Nuclear Medicine

Frontal infundibulum.
Frontal sinus ostium.
Frontal recess.
Uncinate process.

* Middle meatus

EPOS https://dx.doi.org/10.1594/ecr2017/C-2117

frontal sinus drainage pathway and hiatus semilunaris which drains to middle meatus

UWMSK

arrowheads demonstrating frontal sinus recess

frontal recess (arrows), hiatus semilunaris (*) and middle meatus (arrowheads)

Middle Meatus

Drainage of the: frontal sinus (red arrow), the maxillary sinus (yellow arrow) and the ethmoidal bulla (green arrow) into the middle meatus.

EPOS https://dx.doi.org/10.1594/ecr2017/C-2117

Anterior Ethmoid: Drains vis the Ethmoid Bulla ➡Hiatus Semiluniaris ➡Middle Meatus

The ethmoidal cells (sinuses) are located within the ethmoid bone, between the eyes and behind the nose.

They are divided into three groups: anterior, middle, and posterior. The anterior and middle ethmoidal cells open into the middle nasal meatus via the ethmoidal bulla and the semilunar hiatus. The posterior ethmoidal cells open into the superior nasal meatus.

Sagittal CT image showing the superior attachment of the middle turbinate (in blue), dividing the ethmoid cells into anterior and posterior ethmoid cells EPOS https://dx.doi.org/10.1594/ecr2017/C-2117

Basal lamella, the lateral attachment of the middle turbinate to the lamina papyracea.

Coronal and sagittal CT images showing the ethmoid bulla (EB).

EB forms the roof of the hiatus semilunaris (A and B). Anterior ethmoid cells drain into the middle meatus via the ethmoid bulla (C and D). EPOS https://dx.doi.org/10.1594/ecr2017/C-2117

Hiatus semilunaris

Middle meatus

Ostiomeatal unit ( red circle), with the middle meatus (yellow line) between the uncinate process laterally and the

medial turbinate

Anterior ethmoid drainage to hiatus semilunaris and middle meatus. Arrow showing posterior ethmoid drainage to sphenoethmoidal recess and superior meatus

UWMSK

Coronal image with arrowhead showing lateral attachment of basal lamellae to lamina papyracea marked by the arrow. (CG: crista galli, *: cribriform plate, FE: fovea ethmoidalis, MT: middle turbinate, IT: inferior turbinate)

Note the basal lamellae to lamina papyracea

Maxillary: maxillary ostium ➡ infundibulum ➡ hiatus semilunaris ➡ middle meatus.

The maxillary sinuses are located within the maxilla, under the eyes and beside the nose. They are usually pyramidal-shaped and occupy most of the body of the maxilla. The maxillary sinuses drain into the middle nasal meatus via the maxillary ostium.

Maxillary ostium ➡ infundibulum ➡ hiatus semilunaris ➡ middle meatus.

Drainage of the frontal sinus (red arrow), the maxillary sinus (yellow arrow) and the ethmoidal bulla (green arrow) into the middle meatus.

Maxillary Ostium & infundibulum

Sphenoid Sinus, Posterior Ethmoid Sinus & Spenoethmoidal Recess

Posterior Ethmoid & Spenoid ➡ sphenoethmoidal recess ➡ superior meatus

The sphenoidal sinuses are situated within the body of the sphenoid bone, behind the eyes and below the pituitary gland. They are usually asymmetrical and separated by a bony septum.

The sphenoidal sinuses drain into the sphenoethmoidal recess, a space above and behind the superior nasal concha.

Anterior ethmoid drainage to hiatus semilunaris and middle meatus. Arrow showing posterior ethmoid drainage to sphenoethmoidal recess and superior meatus

UWMSK

Note the basal lamellae to lamina papyracea

Sphenoethmoidal Recess

Drainage of the posterior ethmoid cells into the superior meatus. Drainage of the sphenoidal sinus into the sphenoethmoidal recess (orange arrow).

Sphenoid Sinus Ostium

Posterior Ethmoid and Spenoid to Superior Meatus

Axial and sagittal slices showing posterior ethmoid green arrow and sphenoid sinus (red arrow) drainages, in superior meatus

Superior Meatus

Sphenoethmoid Recess

Ostiomeatal complex

The ostiomeatal complex is composed of five structures:

maxillary ostium: drainage channel of the maxillary sinus
infundibulum: common channel that drains the ostia of the maxillary antra and anterior ethmoid air cells to the hiatus semilunaris
ethmoid bulla: usually a single air cell that projects over the hiatus semilunaris
uncinate process: hook-like process that arises from the posteromedial aspect of the nasolacrimal duct and forms the anterior boundary of the hiatus semilunaris
hiatus semilunaris: final drainage passage; a region between the ethmoid bulla superiorly and free-edge of the uncinate process

Radiopaedia

Coronal CT slice showing the components of the ostiomeatal unit

Coronal CT slice showing the drainage passage components in the ostiomeatal unit.

maxillary ostium: drainage channel of the maxillary sinus
infundibulum: common channel that drains the ostia of the maxillary antra and anterior ethmoid air cells to the hiatus semilunaris
ethmoid bulla: usually a single air cell that projects over the hiatus semilunaris
uncinate process: hook-like process that arises from the posteromedial aspect of the nasolacrimal duct and forms the anterior boundary of the hiatus semilunaris
hiatus semilunaris:

Nasal Cavity

Paradoxical turn of middle turbinate

This anatomic variant alone can lead to significant narrowing of the middle nasal meatus and impede the normal drainage of paranasal sinuses due to ostiomeatal complex obstruction

Radiopaedia

Concha bullosa

Concha bullosa (plural: conchae bullosae) (also known as middle turbinate pneumatization) is a common finding and although associated with deviation of the nasal septum, it is usually of little clinical importance.

Notice that a large concha bullosa, may obstruct the drainage pathway of the antrum by distorting the UP and narrowing the infundibulum

Close Call Findings

C: cribriform plate

L: lamina papyracea

O: Onodi cell

S: sphenoid sinus pneumatization

E: ethmoidal artery (anterior)

CLOSE Mnemonic: What to report

The Preoperative sinus Ct: Avoiding a “CLOSE” Call with Surgical Complications. O’Brien et al

Cribriform plate: Type 3 exposes more of the very thin cribriform plate to potential damage...

DOI: 10.7759/cureus.22378

Cribriform plate

The depth of the olfactory fossa is determined by the height of the lateral lamella of the cribriform plate, which can be classified into three categories

type 1: has a depth of 1-3 mm (26.3% of population)

type 2: has a depth of 4-7 mm (73.3% of population)

type 3: has a depth of 8-16 mm (0.5% of population)

The type 3 exposes more of the very thin cribriform plate to potential damage from trauma, tumor erosion, CSF erosion (in benign intracranial hypertension) and local nasal surgery/orbital decompression

Radiopaedia

Type 1

Type 2

Lamina papyracea: Lateral surface of the ethmoid air cells.

The lamina papyracea, also known as the orbital lamina of the ethmoid bone, is the principal component of the medial wall of the orbit, and also the lateral surface of the ethmoid air cells.

Lamina papyracea dehiscence. Right medial orbital wall/lamina papyracea fracture with deviation of the bony wall (arrow) and intraorbital fat (∗) into the ethmoid sinus. Lobulated mucosal thickening is noted within the right maxillary sinus.

The Preoperative sinus Ct: Avoiding a “CLOSE” Call with Surgical Complications. O’Brien et al

Haller Cells

Haller cells, also known as infraorbital ethmoidal air cells, are ethmoid air cells located lateral to the maxillo-ethmoidal suture along the inferomedial orbital floor.

Radiopedia

Left

Bilateral

Left

Onodi air cell: Important due to its close proximity to the optic nerve and internal carotid artery.

Sphenoethmoidal air cell, also commonly known as the Onodi air cell, is an anatomical variant of the paranasal sinuses, important due to its close proximity to the optic nerve and internal carotid artery.

Radiopedia

Bilateral posterior ethmoid air cells that extend along the superior margin of the sphenoid sinuses, consistent with Onodi cells (∗). The optic nerves course through the Onodi cells with a thin bony margin separating them from the sphenoethmoidal air cells (arrows).

The Preoperative sinus Ct: Avoiding a “CLOSE” Call with Surgical Complications. O’Brien et al

Right

Bilateral aerated cavities lateral to the optic canal, extending into the anterior clinoid processes.

Sphenoid sinus pneumatization: The sellar variant is more susceptible to intraoperative injury

(a) Sphenoid sinus: Chonchal (underpneumatization).

(b) Sphenoid sinus: Presellar (pneumatization extends to the anterior margin of the sella).

(c). Sphenoid sinus: Sellar (pneumatization extends posterior to the sella).

The sellar variant results in a thin posterior bony margin of the clivus, which is more susceptible to intraoperative injury (arrow).

The Preoperative sinus Ct: Avoiding a “CLOSE” Call with Surgical Complications. O’Brien et al

Ethmoidal artery: Supraorbital pneumatization puts artery at risk

Supraorbital air cells are an anatomical variant of the paranasal sinuses. They consist of cells originating from the anterior ethmoid air cells extending posteriorly and superiorly over the orbit from the frontal recess. Important due to the anterior ethmoidal artery.

The anterior ethmoidal notch lies in the medial wall of the superomedial orbit, adjacent to the anterior ethmoid air cells.

The anterior ethmoidal notch contains the anterior ethmoidal artery and has significant rates of anatomic variation that put the artery during functional endoscopic sinus surgery (FESS).

Radiopedia

Coronal reformatted CT images demonstrate the anterior ethmoidal notch along the superolateral margin of the anterior ethmoid sinus.

(a) When the ethmoidal notch abuts the fovea ethmoidalis (arrow) or lateral lamella, it is considered protected.

(b) With supraorbital pneumatization of the ethmoid sinus above the ethmoid notch (∗), the anterior ethmoidal artery is at risk for intraoperative injury.

The Preoperative sinus Ct: Avoiding a “CLOSE” Call with Surgical Complications. O’Brien et al