What is the best imaging study for evaluating a septal deviation?

Best Study for Evaluating Septal Deviation

Clinical anterior rhinoscopy and endoscopic examination is the reference standard for evaluating nasal septal deviation, with nasal endoscopy being the most accurate diagnostic method—CT should NOT be performed solely for septal deviation evaluation. 1, 2

Primary Diagnostic Approach

Nasal endoscopy is the first-line confirmatory test for diagnosing deviated nasal septum, offering superior visualization of nasal cavity structures compared to imaging. 2

Endoscopic Technique

• Use either flexible or rigid endoscopes after application of topical decongestant and anesthetic 2
• Visualize critical structures including the nasal cavity, turbinates, meatus areas, uncinate process, hiatus semilunaris, maxillary ostia, ethmoidal bulla, and nasopharynx 2
• Divide the nose into horizontal thirds (upper, middle, lower) and assess each third in relation to the midline 2
• Anterior septal deviation is more clinically significant than posterior deviation as it affects the nasal valve area responsible for more than 2/3 of airflow resistance 2

Role of CT Imaging

CT has limited correlation with physical examination and may underestimate the degree of nasal obstruction due to septal deviation at the internal nasal valve. 1, 2

When CT Is Appropriate

• Only when evaluating associated symptoms of chronic rhinosinusitis, not for septal deviation alone 1, 2
• For preoperative planning when additional sinonasal pathologies are suspected 3, 4
• When unable to evaluate the middle meatus and posterior nasal cavity due to anteriorly severe deviation 4
• When obstructive middle turbinate hypertrophy is present 4
• When chronic sinusitis is suspected based on clinical and endoscopic findings 4

CT Findings (When Performed)

• CT can identify concomitant nasal pathologies in approximately 23.6% of patients with septal deviation 4
• May change surgical decision-making in approximately 8.3% of cases 4
• Useful for measuring deviation angles and classifying severity, particularly anterior deviation angles which correlate with obstructive sleep apnea 5

Alternative Imaging Modalities

Ultrasound

• Shows high accuracy (90-100% sensitivity, 98-100% specificity) for detecting isolated nasal bone fractures 1, 2
• Better detects nondepressed fractures of the nasal bridge and anterior septal cartilage deviation than CT 1
• Not typically first-line for septal deviation evaluation 2

Plain Radiography

• Limited diagnostic value with sensitivity ranging from 53-82% 1
• Does not alter management decisions 1
• Not recommended 1

Critical Pitfalls to Avoid

• Never rely solely on CT imaging without clinical examination—this leads to underestimation of the functional impact of septal deviation 1, 2
• Failing to distinguish between true deviation and nasal asymmetry can lead to inappropriate treatment planning 2
• Approximately 80% of the general population has off-center septum, but only 26% have clinically significant deviation causing symptoms 2
• Nasal endoscopy has higher sensitivity for detecting sinonasal pathologies in patients with mild versus moderate-severe deviation 4