Paranasal Sinus Pneumatization and Conditions

Introduction

Pneumatization is a normal physiologic process (the process of air-filled cells developing as per the size and function of the sinus, which is an air-filled cavity) that is associated with an increase in the size and volume of the paranasal sinuses of the face till adulthood.

How Many Types of Sinuses Exist?

There are mainly 4 sinuses that are paired on either side of the skull bones and are named accordingly based on their location.

1. Frontal Sinus: These are right and left sinuses located on either side just above the eye in the frontal bone of the skull. Though undeveloped and non aerated at birth, it is the last paranasal sinus to form completely, and continued growth occurs throughout childhood to reach its final size shortly after puberty.

2. Maxillary Sinus: These are right and left sinuses that are located on either side behind the cheekbone with the floor at the base of the upper jaws. It is the first paranasal sinus to form, and the maxillary alveolus continues to expand till all the permanent teeth erupt.

3. Sphenoid Sinus: It is located at the sides of the skull in the sphenoid bone (close to the pituitary gland and the optic nerve). At birth, this sinus is totally devoid of air and contains only red marrow or erythropoietic tissue. However, it develops in infants from 7 months to 2 years. Hence, a lack of pneumatization in the sphenoidal sinus past 10 years of age should signify an underlying disease.

4. Ethmoid Sinus: These are collections of multiple sacs of air cells (6 to 12 usually categorized as the front, middle, and rear groups) that open into the nasal cavity. Ethmoidal air cells are present from birth and continue to grow till late puberty.

What Is the Significance of Sinuses?

The importance of these sinuses is directly based on their numerous functions to maintain stability and contour in the face (as the sinuses are hollow air-filled cavities). These include,

1. Primarily the sinuses lighten the skull as they are hollow air-filled cavities.

2. They help in the moisturization of air. The mucus secretions in the sinus are transferred to the nasal cavity lining while breathing.

3. It acts as a protectant against microbial organisms, dust, and environmental pollutants causing respiratory infections.

4. They provide resonance to the voice or vocal cords.

When Does Pneumatization Get Affected?

The possibility of sinus recession is more only in older age groups. Sinuses are also more susceptible to infections that could either be of bacterial or viral origin. The sinus, especially the maxillary sinus that is associated with the roots of the upper molars, is hence rarely excessively pneumatized except in infections.

Similarly, when the sinus pneumatization is reduced, distorted, or displaced, then the source of infections would be due to fatal diseases like neoplasms, orofacial tumors, and fibro-osseous disorders.

As per the research done over the years based on the CT and MRI scans of paranasal sinuses, the normal findings of the pneumatized sinus are well-differentiated through these radiographs from the pathologic findings. The physician needs to understand the normal radiographic picture in CT, and MRI scans regarding the paranasal sinuses to overcome potential difficulties while interpreting the reduction or increase of the distorted sinuses. The maxillary sinus is not only the most prone but also the most commonly infected sinus in various diseases, disorders, and developmental anomalies.

What Are the Symptoms of Paranasal Sinus Disorders?

The sinonasal symptoms that the patient may clinically present in paranasal sinus disorders include,

• Sinus or nasal mucosal pain.

• Fullness or pressure below the eyes.

• Tenderness of upper teeth or upper jaw.

• Pain in the nasal cavity that can mimic a toothache.

• Unilateral pain (on one side of the face).

• Blood or mucus in cough or spit.

• Facial numbness, ear pressure, trismus (trouble opening the mouth), and watery eyes or trouble in the vision like blurry vision, double vision, or vision loss. Such severe symptoms are more associated with neoplastic tumors.

What Conditions Affect Pneumatization?

In the varied pathologic states that mainly alter the physiology and distort the structure of the maxillary sinus, retrospective studies have shown that a majority of pneumatization are caused by carcinomas or tumors, and this is due to the infiltrative nature of these lesions that extend into the sinus cavity. The pathogenesis of maxillary sinus reduction and increase is also associated with iatrogenic or operator caused, traumatic, systemic, or congenital causes.

The conditions affecting pneumatization are classified below.

1) Congenital Causes -

• Maxillary sinus hypoplasia (MSH).

• Treacher Collins syndrome.

• Binder's syndrome.

• Apert’s syndrome.

• Crouzon’s syndrome.

• Hemifacial microsomia.

• Silent sinus syndrome(SSS).

• Craniofacial dysostosis.

2) Conditions Causing Enlargement -

• Mucocele or pneumatocele.

3) Traumatic Causes -

• Facial fractures including zygoma fracture, orbit bone fracture, and maxillary bone fractures.

4) Iatrogenic Causes -

• It is induced by the operator or the physician either accidentally or most often as a side effect of treatment strategies as in common cases of post-Caldwell Luc procedure effects that induce osteogenesis in the sinus cavity or as in irradiation effects.

5) Systemic Causes -

• It can either be hematologic or endocrine abnormalities affecting the bone and soft tissues.

• Osteopetrosis patients have also reported cases of sinus obliteration or distortion.

6) Fibro-Osseous Lesions -

• Paget’s disease.

• Fibrous dysplasia.

• Ossifying fibroma.

7) Cysts of Dental Origin -

• Odontogenic keratocyst.

• Dentigerous cyst.

• Radicular cyst.

8) Odontogenic Tumors -

• Pindborg tumor.

• Ameloblastoma.

• Myxoma.

9) Neoplastic or Malignant Tumors -

• These are common (especially in severe cases of obliterated sinus pneumatization, either causing a reduction or rarely an increase).

• Squamous cell carcinoma.

• Adenocarcinomas.

• Malignant secondary cell carcinomas.

• Melanoma.

10) Primary or Secondary Benign Tumors.

11) Pseudo tumors.

How Can Pneumatization Disorders Be Treated?

Endoscopic sinus surgeries have emerged as the mainline treatment for patients with sinonasal symptoms. This surgery is crucial and quite functional in improving the prognosis of the affected sinus and can aid recovery over time. They are not only minimally invasive by nature but also improve paranasal sinus ventilation and penetration of topical medications.

Preoperative CT scanning is a useful adjunct to recognizing the pathologic state and the varied anatomy of the affected paranasal sinus.

Dental management also plays a role in some cases as the extraction of maxillary teeth in some individuals affects pneumatization (as the roots of the posterior maxillary teeth such as molars or premolars lightly project into the maxillary sinus floor).

Conclusion:

Thus the pneumatization of the sinus that is completed by adulthood is very rarely altered in its dimension or obliterated anatomically except in some mild to moderate pathologic conditions and serious tumors. Consultation with the oral and maxillofacial surgeon or dental surgeon if you suspect sino nasal symptoms will be effective in the long-term management of sinus lesions that affect the paranasal sinuses.