Dear Doctor: I'm contemplating a cochlear implant for my right ear. How do they work, and what is the success rate of such procedures?

Dear Reader: Unlike a hearing aid, which is a mechanical apparatus that amplifies sound, a cochlear implant is a medical device that delivers electrical stimuli directly to the auditory nerve. Hearing aids can be helpful in cases of mild to moderate hearing loss. But for individuals whose hearing loss is severe or profound, a cochlear implant can help.

That said, it's important to understand that a cochlear implant can't offer the same hearing experience as the human ear. And to understand why, we first need to talk a bit about how the ear works. (Are any of our regular readers surprised?)

When we hear a sound, it's because a complex series of functions have taken place. It begins as vibrations traveling through the outer, middle and inner ear. On each phase of that journey, a series of remarkable structures transform those vibrations until they reach the brain and are interpreted as the countless sounds -- and noises -- of the world around us.

Let's say it's raining. The vibrations from droplets striking various surfaces are "collected" by the funnel of the outer ear and an inner auditory canal. At the end of this canal sits the eardrum, which connects to a trio of tiny bones. These pick up and amplify the vibrations, and transmit them to the snail-shaped cochlea in the inner ear. Within the cochlea, a fluid begins to ripple. When tiny hair-shaped sensory cells touch a membrane, chemicals that create an electrical signal are released. This signal travels along the auditory nerve to the brain, which presents us with the sound of rainfall.

With a cochlear implant, which is made up of two parts, vibrations bypass the hair cells of the inner ear. Instead, the speech processor, worn behind the ear like a hearing aid, sends the information directly to a receiver-stimulator, a small device that is surgically placed beneath the skin. Electrodes from the receiver connect via the cochlea to the auditory nerve. When the processor picks up sound, the receiver turns it into electrical impulses and sends them to the brain. But because the hair cells within the cochlea, which give us the countless nuances of sound, are not involved, the hearing experience is not the same.

How well someone does with a cochlear implant depends in part on what degree of hearing they began with. Learning to interpret the impulses sent by the implant takes practice and can be challenging. Like hearing aids, there are several varieties of implants, and all can be adjusted to best fit the user's needs.

Risks include nerve injury, infection, meningitis, numbness around the ear, vertigo, tinnitus and the risks associated with anesthesia during the initial operation. Some implants fail and must be removed. For people with implants, scans like an MRI may not be possible.

Today, well over 60,000 adults in the United States use implants. If you do move forward, we suggest getting in touch with an organization that offers assistance to people who are deaf and hard of hearing. Also, going to a support group for cochlear-implanted patients can be a good way to get firsthand feedback.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Could you please explain Creutzfeldt-Jakob disease? Some people call it "mad cow disease," which gives it a stigma. I lost my twin brother to this disease, and it's left our family shattered.

Dear Reader: I am truly sorry for your loss. My family also lost a loved one to this devastating disease. We could only watch helplessly as it quickly took away all vestiges of the person we once knew.

For those unfamiliar with it, I'll explain: Creutzfeldt-Jakob disease (CJD) is the most common prion disease in humans. (The others are predominantly found outside the United States.) Prions are infectious, but they're not viruses or bacteria; they're proteins. They appear to be created from normal proteins found on cell membranes. The normal proteins may help inhibit cell death, but in prion diseases, they reconfigure. This initial change is believed to be related to an external agent, possibly a virus, chemical or drug, in 85 to 95 percent of patients and to a genetic cause in 5 to 15 percent of patients.

The term "mad cow disease" is actually a misnomer, because the majority of cases are not related to prion transmission between cows and humans. It can happen, of course, such as the 1990s outbreaks in the United Kingdom that led to the term. But these animal-to-human transmissions of prions, termed Variant Creutzfeldt-Jakob disease, are very rare. Even more rare is human-to-human transmission via transplanted livers, cornea and brain tissue.

Regardless of the cause, exposure to abnormal prions leads to a cascading effect -- the creation of more abnormal prions that disrupt nerve cells' function and lead to their death. This destruction causes holes within the brain tissue, leaving it with a spongelike appearance.

The disease initially interferes with concentration, memory and judgment and leads to episodes of sleep throughout the day. In terms of mood, a person may at first seem neglectful, apathetic and depressed, quickly giving way to unrelenting mental deterioration. Patients eventually develop dementia and can lose the ability to control muscle movements, resulting in twitching or jerking contractions of the muscles. Progression is slower for people younger than 50, but regardless, death usually occurs within one year of symptom onset, with an average time to death of six months.

The only positive in this scenario is that CJD is rare, affecting one in a million people per year.

Many other diseases can initially appear similar to CJD, which is diagnosed with an assessment of symptoms, aided by electroencephalograms (EEGs) and MRIs of the brain. Protein markers in spinal fluid can also help. But the best way to definitively diagnose CJD is to look at brain tissue, most often done at autopsy.

As you already know, there is no good treatment for CJD. Flupirtine, a drug available in Europe, can protect cognitive function to some degree, but does not alter survival. Quinacrine and chlorpromazine can inhibit the formation of abnormal prions but have not shown an ability to stop the disease.

That isn't to say research has stopped, only that it hasn't made huge strides. Everyone who has watched anyone suffer with CJD is hoping science can ultimately find a way to treat this terrible disease. In the meantime, we can all help educate others as to the real nature, and name, of Creutzfeldt-Jakob disease.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: How important is it to keep track of a child's blood pressure? I read that the American Academy of Pediatrics just updated its guidelines for screening and managing high blood pressure in kids. Is this really a problem that I need to worry about?

Dear Reader: We're so glad you brought up this very important topic. Blood pressure is a diagnostic tool that's as important in children as it is in adults. However, because blood pressure readings in children are evaluated by a different set of metrics than those of adults, the subject has often been confusing.

By now, the significance of high blood pressure, or hypertension, is well known to most of us. It's not a condition that you can readily feel, but when left untreated it can cause significant damage to your body. By the time symptoms appear, you can be dealing with a host of problems, including damage to your heart, kidneys, eyes, bones and cognitive function.

High blood pressure in children can be a predictor of the condition later in life. It can cause certain types of damage to the structures and blood vessels of a child's heart. And it can be a symptom of other serious underlying conditions, including heart or kidney problems. Between 2.2 to 3.5 percent of children have high blood pressure, according to the new guidelines. The number jumps up to 24 percent among children who are obese or overweight. Children who were born prematurely and those with sleep-disordered breathing are also at risk of high blood pressure.

That's why establishing a baseline blood pressure reading beginning as early as the age of 3 is important. After that, a child's blood pressure should be measured during annual physical exams, and the trajectory of those readings over time should be noted and used as a diagnostic tool.

Thanks to the new blood pressure guidelines, released in August 2017 by the American Academy of Pediatrics, this should be much more easily accomplished. Unlike in adults, whose blood pressure readings fall into uniform parameters, readings in children must be interpreted based on gender, age and height. It's no surprise that, with so many variables to deal with, repeated studies show that up to 75 percent of children with high blood pressure have gone undiagnosed.

Before, health care professionals had to delve into multiple pages of charts to assemble the numbers and come up with a reading. The updated guidelines have simplified this pile of data into a single table. It's easy to use and easy for everyone, including parents, to understand.

For a child to be diagnosed with high blood pressure requires three separate readings that fall above the established guidelines. A single high reading, while not a diagnosis, does indicate the need for subsequent evaluations to rule out hypertension.

If your pediatrician or family physician doesn't routinely check your children's blood pressure, don't be afraid to ask. With one-third of adults in the United States now diagnosed with hypertension, it's clear that it's never too soon to get ahead of this serious condition.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)