Epithelial migration on the external ear canal wall in normal and pathologic ears

Area of Science:

• Otolaryngology
• Auditory Canal Physiology
• Dermatology

Background:

• Epithelial migration on the tympanic membrane is well-studied, but less is known about migration on external auditory canal (EAC) walls.
• Keratosis obturans (KO) is a condition characterized by keratin accumulation in the EAC, potentially affecting epithelial dynamics.

Purpose of the Study:

• To investigate and compare epithelial migration patterns on the EAC wall in healthy individuals and patients with keratosis obturans.
• To quantify the rate and direction of epithelial migration in different EAC quadrants.

Main Methods:

• Ink dots were applied to the tympanic annulus at four quadrants in 25 healthy subjects and 4 KO patients.
• Migration of ink dots towards the bony cartilaginous junction was tracked and photographed over time.
• Rates of migration were calculated in micrometers per day (μm/d) for each quadrant.

Main Results:

• In normal ears, ink dots migrated at rates between 42–205 μm/d, with slower migration observed in the anterior and inferior quadrants.
• The single KO patient exhibited variable migration rates (88–140 μm/d) with abnormal desquamation in the inferior quadrant halting ink dot progression.
• Abnormal keratin resurfacing in the KO ear interfered with normal epithelial migration.

Conclusions:

• Epithelial migration on the EAC wall follows a generally linear pattern but varies in speed across quadrants in healthy ears.
• Keratosis obturans is associated with localized areas of abnormal keratinization that impede epithelial migration on the EAC wall.