Is anosmia an indication for CT of the Paranasal Sinuses (PNS)?

From the Guidelines

Anosmia is a recognized indication for CT of the Paranasal Sinuses (PNS), particularly in patients presenting with persistent or recurrent symptoms, such as sudden onset of anosmia or hyposmia, in the absence of nasal congestion or other obvious causes 1.

Key Points to Consider

• Patients with anosmia may undergo CT PNS with or without contrast to evaluate for potential underlying conditions such as chronic sinusitis, nasal polyps, or tumors 1.
• The CT scan protocol typically involves a non-contrast enhanced scan with 1-2 mm slice thickness, reconstructed in axial and coronal planes, to provide detailed visualization of the paranasal sinuses and surrounding structures 1.
• CT without contrast is indicated for imaging bone, sinus anatomy, ostiomeatal complex, and shows soft tissue–air–bone contrast, and is suitable for patients with recurrent acute sinusitis, chronic sinusitis, preoperative for sinus surgery, nasal polyposis, persistent nasal congestion-obstruction, immunocompromised patient with fever, dentomaxillary pain, facial pressure–headache unresponsive to medical therapy, and anosmia after appropriate workup 1.
• MRI provides excellent soft tissue differentiation, but does not image bone or the bony anatomy required for surgery, and is indicated for skull base dehiscence with opacification, unilateral sinonasal opacification, sinonasal process with cranial extension, expansile sinonasal mass with bony erosion, sinonasal mass with orbital extension, biopsy-proved tumor, and fungal sinusitis 1.

From the Research

Anosmia and CT of the Paranasal Sinuses (PNS)

• Anosmia, or the loss of smell, can be an indication for a CT scan of the Paranasal Sinuses (PNS) in certain cases, as evidenced by studies 2, 3.
• A study published in 2023 found that PNS CT findings were significant in patients with COVID-19 who experienced a loss of smell, and were associated with the degree of loss of smell 2.
• Another study from 2021 found that the opacification degree of the paranasal sinuses on CT was correlated with clinical symptoms, including hyposmia/anosmia, in patients with chronic rhinosinusitis 3.
• However, the decision to perform a CT scan of the PNS should be based on a thorough evaluation of the patient's symptoms and medical history, as well as the presence of other indications for the scan.

Indications for CT of the PNS

• CT scans of the PNS are commonly used to evaluate patients with chronic rhinosinusitis, nasal polyposis, and other conditions that affect the paranasal sinuses 4, 5, 6.
• The scan can help identify anatomical variations, mucosal changes, and other abnormalities that may be contributing to the patient's symptoms.
• In some cases, a CT scan of the PNS may be used to evaluate the extent of disease and plan surgical treatment, such as functional endoscopic sinus surgery (FESS) 6.

Correlation between Anosmia and PNS CT Findings

• Studies have found a correlation between the opacification degree of the paranasal sinuses on CT and the severity of anosmia in patients with chronic rhinosinusitis and other conditions 2, 3.
• The presence of anatomical variations, such as septal deviation and concha bullosa, may also be associated with anosmia and other symptoms 4, 6.
• Further research is needed to fully understand the relationship between anosmia and PNS CT findings, and to determine the optimal use of CT scans in the evaluation and treatment of patients with anosmia.