Spoke sign may highlight pediatric middle ear effusion

By Liam Davenport, medwireNews Reporter

The presence of a specific finding on otoscopy known as the spoke sign (SS) may help in the detection of middle ear effusion (MEE) in pediatric patients, although its incorporation into clinical practice may require focused training, say US scientists.

"With such training, it appears that the SS is a very sensitive and specific marker for pediatric MEE," suggest Shankar Sridhara and Scott Brietzke, both from the Walter Reed Military Medical Center, in Bethesda, Maryland.

They add in the Archives of Otolaryngology Head & Neck Surgery: "The advantage of using the SS in clinical practice is that determining its presence requires only quick visual inspection, and so it is more feasible to perform on a consistent basis in the office setting."

Sridhara and Brietzke defined the SS as a dull gray appearance of the tympanic membrane with engorged vasculature in an arrangement similar to the spokes of a bicycle wheel, covering 50% or more of the inferior tympanic membrane by area. They noted the presence or absence of SS before myringotomy in 150 ears of 67 patients with a mean age of 2.13 years.

Analysis showed that 64% of patients had SS in at least one ear. In all, SS was present in 84 ears, of which 79 had MEE, indicating a positive predictive value of SS for MEE of 94%. The sensitivity of SS for predicting the presence of MEE on a per-ear analysis was 100%, while the specificity was 93%, positive predictive value still 94%, and negative predictive value 100%.

The researchers briefly educated a group of independent pediatricians and otolaryngology residents and provided them with a short verbal and written definition of the SS to assess the inter-rater reliability of the SS. The physicians were then shown 27 videos obtained intraoperatively before myringotomy and asked to indicate whether they believed the SS to be present.

The Fleiss kappa value for inter-rater concordance among pediatricians was between 0.21 and 0.40 for determining the presence of the SS and MEE, indicating fair concordance. For otolaryngology residents, the Fleiss kappa value was between 0.61 and 0.80, indicating substantial concordance. This demonstrates otolaryngology residents may need specific training in otoscopy to optimise the usefulness of the SS, the authors say.

Sridhara and Brietzke conclude: "The SS is a simple visual diagnostic aid that was found to be present in most pediatric patients with MEE who were undergoing tympanostomy tube placement. The diagnostic performance of the SS in comparison with the criterion standard of myringotomy was excellent, with high measured sensitivity and specificity."

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