PoCUS For Maxillary Sinusitis

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PoCUS Clinical Pearl by Dr. Chew Kiat Yeoh

 

 

DalEM PoCUS Fellow

Reviewed by: Dr. David Lewis

 

 

 

Background

  • Acute rhinosinusitis is an inflammatory disease of nasal mucosa and paranasal sinuses. It is one of the most common ED presentations and fifth most common diagnosis for which antibiotics are prescribed (1).
  • It affects more than 30 million adult each year (2).
  • Accurate diagnosis of acute maxillary sinusitis based on clinical examination is unreliable (3) because the signs/symptoms are nonspecific.
  • Although radiographic imaging improves diagnostic accuracy, it is not recommended in uncomplicated sinusitis (4) due to radiation risk, additional costs, and time.

 

How accurate is PoCUS in identifying maxillary sinusitis?

  • Gold standard for diagnosing maxillary sinusitis is positive fluid culture obtained from sinus puncture (5). However, this method is invasive, unnecessary, and often not easily accepted by patient.
  • Ultrasound has been used to diagnose acute maxillary sinusitis as it is rapid, safe, and non-invasive.
  • Ultrasound is very sensitive in identifying fluid in sinus cavities, with accuracies more than 90% for the diagnosis of maxillary sinusitis have been reported in otolaryngology (ENT) practices.
  • While the result from ENT practices might not be applicable to the ED setting due to different patient demographic and severity of disease. When PoCUS performed by Emergency Physician compared to CT in ED patients with suspected maxillary sinusitis, the sensitivity and specificity are 81% and 89%, respectively, for diagnosis of maxillary sinusitis (7). The agreement between the two methods was 86%.
  • Study using MRI as gold standard, ultrasound was found to have 64% sensitivity and 95% specificity, compared to 73% sensitivity and 100% specificity for plain XR (6).
  • Overall – ultrasound is sensitive in detecting fluid in sinus cavities and highly accurate (>90%) in diagnosing maxillary sinusitis.

 

Scanning Technique

  • Position: sitting upright or lean slight forward to ensure sinus fluid if present, would layer out against the anterior wall.
  • Probe: High frequency (4 to 12 MHz) linear array transducer with adequate depth penetration (5-7cm) to visualize the entire sinus cavity Or phased-array probe if depth required.
  • Scan the maxillary sinus in between lateral nose and zygoma in at least two planes: transverse & sagittal (Figure 1).
  • Always scan the contralateral normal side is for comparison.

Ultrasound Features

Normal Ultrasound Appearance of Maxillary Sinus

 

 

The Ultrasound Appearance of Maxillary Sinusitis

  • If the sinus cavity is fluid filled (complete or partial), the ultrasound signal will be able to penetrate through the thin hyperechoic anterior wall, and the surrounding walls (posterior, medial, lateral) of the sinus will be visualized and seen as a bright echogenic line.
  • Positive Ultrasound finding : Presence of posterior wall echo >3.5 cm from the initial echo (3) (anterior maxillary wall)

 

Partially Filled: Partial Sinusogram

 

Completely Filled: Complete Sinusogram

 

 

The significance of the Pathology and how can PoCUS add value?

  • More than 1 in 5 antibiotics prescribed in adults are for sinusitis. It is the fifth most common diagnosis which antibiotics is prescribed.
  • Rhinosinusitis is a common disorder, however, only 50% of patients presenting to the acute care setting with sinus symptoms have acute bacterial sinusitis.
  • Although, ultrasound is not accurate as CT and MRI, it is a more practical adjunct bedside tool that can be rapidly, safely and routinely used to assess those with sinus symptoms and for diagnosing uncomplicated sinusitis in acute care settings and could potentially reduce unnecessary over prescription of antibiotic use.

 

Pearls and Pitfalls

  • Ultrasound is not helpful in differentiating between a viral and or bacterial sinusitis.
  • Positive sinusogram can also be caused by significant mucosal thickening, polyps, fluid-filled cysts, masses and blood from facial trauma or sinus fractures. All these can be mistaken for acute sinusitis.
  • Technical failure includes inadequate depth setting to properly visualize the posterior wall and improper position(supine).

 

References

  1. Summary E. Otolaryngology – Head and Neck Surgery Antimicrobial treatment guidelines for acute bacterial rhinosinusitis. 2004;130(January):1-45. doi:10.1016/j.otohns.2003.12.003
  2. Rosenfeld RM, Andes D, Bhattacharyya N, et al. Clinical practice guideline : Adult sinusitis. Published online 2007:1-31. doi:10.1016/j.otohns.2007.06.726
  3. Varonen H, Mäkelä M, Savolainen S, Läärä E, Hilden J. Comparison of ultrasound , radiography , and clinical examination in the diagnosis of acute maxillary sinusitis : a systematic review. 2000;53:940-948.
  4. Aring ANNM, Chan MM. Acute Rhinosinusitis in Adults. Published online 2011:1057-1063.
  5. Carolina S, Sur- N, Hospital HF, Cen- HM, Carolina S. Maxillary sinus puncture and culture in the diagnosis of acute rhinosinusitis : The case for pursuing alternative culture methods. Published online 2000:7-12. doi:10.1067/mhn.2002.124847
  6. Puhakka T, Heikkinen T, Makela MJ, et al. Validity of Ultrasonography in Diagnosis of Acute Maxillary Sinusitis. Arch Otolaryngol Head Neck Surg 126(12):1482–1486, 2000.
  7. Price D, Park R, Frazee B, et al. Emergency department ultrasound for the diagnosis of maxillary sinus fluid. Acad Emerg Med. 2006;13(3):363-4

 

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