On Migration

Jul 19, 2018 3:39 AM

I am going to talk about migration, but not the kind you’re thinking. This is an article about epithelial migration. Particularly epithelial migration in the ear canal. 

An ear canal, averages one inch long and one-third inch in diameter. It flows up and back in a gentle ’S’ curve. The skin on the outer half is pretty much like the rest of the skin on your body. If damaged, it will heal in the usual manner .  Normal skin cells develop in deep tissue and migrate upward,  until they reach the surface, die, and fall off. The term for shedding dead skin cells is desquamation. 

The skin of the inner ear canal is different.  It is more keratin based, similar to your hair and finger nails. This inner half is often referred to as the bony portion of you ear canal because it is surrounded by bone, while the outer half is surrounded by cartilage.   

When this keratin grows, it starts at a basal location and migrates laterally, this is called epithelial migration. The epithelial migration of your inner ear starts at your ear drum. Your ear drum is composed of three layers, and the top layer grows outward radially along your ear canal. This layer is extremely thin like a dragonfly wing and very easily damaged. This is one of the main reasons you should not insert any objects into you ear canal, even Q-tips.

Hair, and fingernails will keep growing until you cut them, the skin of your inner ear canal goes through a desquamation process. The point where the inner bony portion meets the cartilaginous outer section is called the isthmus because your ear canal narrows there. Epithelial migration continues to occur up to the isthmus where it meets the “normal” skin. It then curls inward, and unsupported by the underlying bone, it crumbles away.

Occasionally this process of epithelial migration and desquamation does not function properly, and problems can develop. 

“As it is with all health issues, early detection is the key to better outcomes,” says Dan Rochel of Hearswell in Isanti. The method of viewing into an ear canal for inspection is called otoscopy. “We visually inspect the ear canal at every appointment using a video-otoscope, so our patients can see what we see” says Rochel.

The most benign of these issues is a false eardrum. This occurs when, instead of crumbling away the thin layer of keratin curls to block the ear canal. Oftentimes earwax will build up on this thin layer of skin. This can cause very mild hearing loss, and is easily remedied by the removal of the dead skin layer. 

Keratosis obturans is similar to this condition, but instead of the thin layer curling up, it piles up into a much thicker plug. In addition to hearing loss, this can cause tissue damage and scarring. The remedy can be as simple as removing the plug. If left too long the plug needs to be excised surgically. 

A  Cholesteatoma is another issue that  occurs deeper in the ear canal. This happens when the desquamation process forms a pocket between the skin and bone. These are dangerous and complications include bone and nerve damage. Cholesteatomas need to be surgically removed and often causes permanent damage to hearing and anatomical structure. 

At Hearswell, ear canal inspections  are part of the standard clinical practice. If you have questions about ear anatomy, or other hearing related issues, Give them a call.