How does hydrops cause Meniere attacks?

The first thing a person has to have in order to have a Meniere attack is endolymphatic hydrops, a ballooning of the endolymph-filled labyrinth with a decrease of the cushioning perilymph fluid surrounding it.  Normally these compartments have a careful pressure-regulating system that keeps them from ballooning. Since the inner ear is a pressure sensor—sound exerts a slight pressure wave that the ear picks up, and so does movement—it is important that the ear has a constant, low pressure to allow these slight waves to be detected. When hydrops develops, it indicates that pressures have started to fluctuate.

One reason pressures need to be low and steady in the ear is that blood flow is critical.  To get blood to flow, it must come in at a higher pressure in the arteries, supply the tissues, then exit at a much lower pressure in the veins.  Like other structures in the skull, the inner ear is able to auto-regulate the blood flow.  It can open or constrict the arteries to keep flow even, no matter how high or low the blood pressure is in the rest of the body (within limits of course).  This protects the ear.  When hydrops occurs, the ear loses this ability to regulate flow, and blood pressure in the vessels can be sometimes be too high or too low. 

The hydropic ear gives hints when the pressures are too high or too low.  When low, there is more blood flow, and you might hear or even feel a pulse in the ear.  When too high, the ear feels tight, the hearing goes down a little, and you may notice an increase in tinnitus, a low-pitched roaring sound or blowing sound in the ear.  This is an indicator that the ear is on the edge of an attack. 

You can control some of the pressures in hydrops.  Fluid builds up when you eat a lot of salt, so you want to watch this.  It’s higher when your head is at the level of your heart or lower, so it’s higher at night or when bending over.  Sleeping with the head propped up can help.  It also fluctuates with barometric pressure.  Low atmospheric pressure during a storm can make the inner ear balloon, and the high atmospheric pressure that usually follows a storm can then set off an attack.  Having a barometer can help you know when an attack is likely to happen.  If the barometer effects are strong, a tympanostomy tube in the eardrum can reduce this. 

In my next post, I’ll explain how vascular disease starts the severe attacks.