Eardrum crust aids perforation healing if timing is right

By Sally Robertson, B.Sc.Jan 22 2013

How and when "crust" forms at the margin of a tympanic membrane perforation (TMP) may serve as a predictor for healing outcome, research suggests.

"Compared with perforations with early crust formation or no crust, late crust formation can result in delayed healing and failure to close completely," says Zhengcai Lou (Wenzhou Medical College, Zhejiang, China).

"Simply put, early crusts appear to be a good sign, and late crusts a bad one."

The analysis of otoendoscopic videos available for 83 patients with acute TMP showed that 29% of patients did not form a crust, while 39% had early crust formation (within 1 week of injury), and 32% had late crust formation (>1 week after injury).

Six months after injury, no significant differences were seen in closure rate between the groups with no crust and late crust formation or between the early crust formation and no crust groups.

However, participants with early crusting exhibited a significantly higher rate of healing compared with patients who had late crusting, at 100% versus 78%.

Furthermore, time-to-closure did not differ significantly between the early crust formation and no crust groups, but the late crust formation group exhibited significantly delayed TM healing compared with the early crust formation and no crust groups, at 38.1 days versus 18.2 days and 20.4 days, respectively.

As reported in the American Journal of Otolaryngology, those with early crust formation had reddish-brown blood clots or everted eardrums at the perforation margins or on eardrum surfaces within 2 to 3 days of injury.

"Blood exudate accelerates the healing of eardrums and full-thickness skin wounds," explains Lou. Additionally, existent bloody discharge indicates a rich capillary meshwork and abundant blood supply of the eardrum that would be beneficial to healing.

In patients with late crust formation, a yellowish-brown crust gradually appeared at the perforation margins about 2 weeks post-injury.

"Late crusts are related to the excessive desquamation and outward migration of epidermal cells, possibly sealing perforation edges and preventing perforation closure mechanically, thereby resulting in delayed healing of a traumatic TMP, or even failure to close," explains Lou.

"Early removal of any late crusting near the perforation margin might help prevent late-formed crust from sealing the perforation edges and avoid mechanical prevention of perforation closure, thereby accelerating eardrum healing," he suggests.

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