Introduction: Types of Complications of Acute Rhinosinusitis
Most complications of acute rhinosinusitis (ARS) respond well to medical treatment; however, a small percentage may worsen as the infection spreads to adjacent structures.
The location and timing of these complications are closely related to the development of the paranasal sinuses and their proximity to the orbit and brain. Sinusitis complications are classified as follows:
A. Orbital complications
B. Intracranial complications
C. Bone complications
Pathogenesis
Complications of ARS primarily affect the orbit and brain due to their proximity to the paranasal sinuses. The infection can spread to these structures through several mechanisms. One mechanism involves a dehiscence in the bony wall, which can be congenital, secondary to trauma, or the result of bone destruction caused by osteitis (bone inflammation). Another mechanism is hematogenous spread, facilitated by the valveless ophthalmic venous system, which allows the infection to travel from the sinuses to the cerebral venous system.
A. Orbital Complications of Acute Rhinosinusitis
These are the most common complications (70%) and primarily affect the pediatric population. They are classified based on the degree of orbital involvement:
- Periorbital cellulitis: Characterized by eyelid swelling without impairment of visual acuity or eye movements.
- Orbital cellulitis: Involves eyelid swelling, conjunctival edema, and outward displacement of the eyeball, but visual acuity and eye movements remain unaffected.
- Subperiosteal abscess: A purulent collection adjacent to the bone, causing limited eye movement.
- Orbital abscess: A purulent collection within the orbit, leading to ocular paralysis with marked protrusion of the eyeball.
B. Intracranial Complications of Acute Rhinosinusitis 
These account for 20% of ARS complications and primarily affect adolescents and adults. This category includes any infection involving the central nervous system (CNS):
- Epidural abscess
- Subdural abscess
- Empyema
- Meningitis
- Intracerebral abscess
- Dural sinus thrombosis (cavernous sinus thrombosis)
These conditions are characterized by severe systemic involvement, presenting with intense headache, altered consciousness, focal neurological deficits, neck stiffness, and other CNS-related symptoms and signs.
C. Bone Complications of Acute Rhinosinusitis
Bone involvement accounts for 10% of all ARS complications and affects the bone surrounding the sinus. This can occur in any of the paranasal sinuses in both acute and chronic rhinosinusitis. The most common conditions are:
- Osteomyelitis of the maxillary sinus: May involve the orbital floor or lead to a fistula in the oral cavity.
- Osteomyelitis of the frontal sinus: When accompanied by a collection on the patient’s forehead, it is known as Pott’s puffy tumor and is often associated with intracranial complications.
Diagnosis
Diagnosis of these complications is primarily clinical, based on history and physical examination findings.
- Physical examination: Includes ophthalmological or neurological assessment as needed and nasal endoscopy to confirm purulent discharge from the paranasal sinuses.
- Laboratory tests: A general blood test is usually ordered, and blood cultures are obtained depending on the patient’s condition.
In more complex cases, contrast-enhanced CT imaging is essential to confirm the presence of an orbital or intracranial abscess.
Treatment of Complications of Acute Rhinosinusitis
Given the severity of these complications, hospitalization is usually required for intravenous treatment and close monitoring of the patient. Most patients, except in some exceptions, will require surgical intervention in addition to medical treatment to drain collections and open the affected paranasal sinus.