Auditory week began at 8:00 am with some classmates upset because the room was different than stated on the shared Google Calendar that is our primary source of scheduling information: “Ugh, now I have to pack all my things up.” We moved across the hall and Doctor J tried to reassure the class by promising it wouldn’t happen again.
The ear is involved in hearing and balance. The pinna (outer ear flap, also called auricle) funnels sound into the ear canal to strike the tympanic membrane. On the other side of the tympanic membrane is the middle ear, an air-filled cavity that is connected to the oral cavity through the eustachian tube. We practiced using otoscopes on each other in a clinical workshop led by a female otolaryngologist in her 40s. It hurt! Every few minutes we would hear a shrieking “ouch”. The worst was when a student from one group hastily grabbed a new tip to practice the technique lurched over and hit another group’s otoscope wielder. The otoscope twisted in the student’s ear. Despite these mishaps, we learned a great deal. After you get past the ear wax and hair, the tympanic membrane comes into view. The malleus, one of the three ossicles (ear bones), is attached at the umbo, a small white spot near the center of the tympanic membrane. In a normal ear you can see the pale outline of the malleus through the transparent membrane.
The otolaryngologist went over some commonly diagnosed ailments using the otoscope. A more opaque tympanic membrane suggests fluid, instead of air, is behind the tympanic membrane in the middle-ear. The fluid is typically from a middle-ear infection, which can cause temporary hearing loss and pain. She explained that we can also diagnose pierced ear drums and grossly malformed ossicles. A student asked, “What are the common procedures you do?” The answer was removing the broken ends of Q-tips from the ear canal. He followed up with “Do ENTs promote the use of Q-tips for business reasons?” She laughed and responded, “Oh, God, no! Those visits are so boring.” Her passion is performing cochlear implants to restore hearing in children (see below).
When a sound wave hits the tympanic membrane, the membrane transmits the vibration to the the ossicles. The malleus (“hammer”) rotates the incus (“anvil”), which in turn displaces the stapes (“stirrup”). The stapes is the interface between the middle ear and the cochlea, a fluid-filled, snail-shaped bone of the inner ear. The stapes lies in the oval window, described as a “bony defect” of the inner ear, that interfaces the stapes with the encapsulated fluid (note that if you didn’t have this “defect” you wouldn’t be able to hear). The stapes transmits the mechanical energy to propagate a pressure wave through the tube to the exit at the round window (a “bony defect” of the inner ear interfacing with the air-filled middle ear). The cochlea is U-shaped, with the oval window opening into the scala vestibuli. The 360-degree turn is called the heliotrema, and the scala tympani ends at the round window.
The two divisions of the tube (scala tympani and scala vestibuli) are separated by a space, the scala media, another fluid-filled tube. This turns out to be the actual source of all hearing sensation. The scala media changes in thickness along the length of the tube, making it sensitive to different sound frequencies. For example, one frequency might lead to a high pressure in the scala vestibuli 1 mm from the oval window, and a low pressure in the scala tympani 1 mm from the round window. This signal would cause the scala media at this region to bend towards the scala tympani. Along the length of the scala media are hair cells, receptors that excite neurons when the scala media deforms as little as a few nanometers. The sensation of sound occurs when signals travel through the brain stem into the primary auditory cortex, part of the surface of the brain that happens to be near the ears. A cochlear implant works by turning the varying voltage from a microphone into nerve signals corresponding to what would have been the movements of the hair cells.
As will become important in the patient case below, the scala media is continuous with another fluid-filled bone, the vestibular apparatus, an accelerometer critical for balance. This tube is divided into three thin canals (sensing rotation) and two sacs (sensing linear acceleration). Due to inertia, the fluid inside the tube will tend to stay put as the head moves, enabling hair cells to sense a change in pressure within any of the five compartments.
I ate lunch outside with Straight-Shooter Sally. She is the first person in her family to go to college, let alone medical school. Her father is a mechanic. She worked for three years after college as a social worker with adolescent drug addicts in a poor urban neighborhood. “These kids quickly get involved with the drug scene,” explained Sally, “Drugs are the easiest avenue to create friend groups and to avoid attack by the gangs. When kids get arrested they are given the option of going to juvy or rehab. Everyone choses rehab.” Does rehab work? “Every summer I would come back and see the same kids. It was a revolving door and we did not have any tools to make a difference. The three-month rehab was nothing for them. Their father went to jail for three years—what’s rehab speaking to a counselor for a few months?” She continued, “These kids go to failing schools, come home to disorganized families, and the only thing they aspire to is what they see in the community. The drug dealers are the ones who have the snazzy cars, women, and money.” She concluded, “I don’t know the answer, but these kids need help—education, role-models, jobs, anything. Counseling was not going to solve it. I had to get out of there.” She switched jobs and became a health coordinator before starting medical school at age 28.
Our patient case: Giorgio, a 50-year-old salesman who developed right ear pressure and diminished hearing after an evening shower. When he woke up, his ear felt like it was about to “pop” and he had lost all hearing on that side. Two common tests with tuning forks, the Rhine and Weber tests, suggested that the hearing loss was due to a sensory-neuronal deficit rather than a conduction deficit. In other words, he had damage to the hair cells, cochlear nerve, or brain cortex, rather than a mechanical blocked ear or perforated tympanic membrane. An MRI revealed an acoustic schwannoma, a non-malignant tumor of the supporting Schwann cells of the vestibulocochlear nerve as it exits the internal acoustic meatus into the cranial cavity. The tumor had begun to squeeze the cochlear nerve. “Most acoustic schwannomas grow less than one millimeter per year,” said the neurologist. “Some years they just lay dormant. For whatever reason, they might spike for a few months then go back into a dormant state.” Georgio’s tumor was removed by a surgical resection through a retrosigmoid craniotomy approach (incision behind the ear).
The neurosurgeon (not Giorgio’s surgeon) explained the risks. “It all depends if the tumor has facial nerve involvement.” The facial nerve exits the cranial cavity in the same hole, the internal acoustic meatus, as the vestibulocochlear nerve. If you touch these fibers, it can lead to ipsilateral facial paralysis.” During the surgery they insert electrodes into the facial nerve to verify, after each layer of tumor is removed, normal conduction from the surgical site to the facial muscles. “There is not a consensus on whether the whole tumor should be removed if there is facial nerve involvement. If you can get, say, eighty percent of the tumor, you might be able to resolve the hearing deficients and decrease the risk of facial nerve damage. But, the tumor could slowly grow back.” My classmates and I watched a Youtube video on the surgery (https://www.youtube.com/watch?v=PBE5rQ7B0Ls). “This is wild,” exclaimed an aspiring female surgeon.
Giorgio underwent a full resection. He quickly regained most of his hearing. “I have worse hearing in my right ear, especially in the higher frequencies. For the most part, I hear fine.” He does have persistent tinnitus (ear ringing). “Right now, focusing on it, I hear it, but I get used to it.” He experienced terrible balance issues for months after the surgery. “I had to completely relearn how to walk. My whole balance seemed to have just reset to a new normal. I was completely dependent of my family for three months.” He also experienced a poorly healing wound on the skull behind the ear. “I was taking airline trips for my job with an open wound on my head. Not the most sanitary environment. One day in the car, my wife looked at my wound, and forced me to go see a plastic surgeon.” The plastic surgeon performed a skin graft to revascularize the infected wound. The wound healed shortly thereafter. The neurosurgeon added, “I see these occasionally. It’s not a petrid, ozzy infection. It’s a lingering infection.” Despite this complication, Giorgio was very satisfied with his care. He is slowly getting back into playing competitive tennis, although he still experiences balance issues.
We learned that Giorgio immigrated to the US as a student. He still maintains citizenship from his Scandinavian birthplace. A classmate asked what kind of treatment he would have received under the socialized medicine system of his birth country. “Completely differently,” explained Giorgio. “I would not have been allowed to get operated on. If it is not considered life-threatening or malignant they would not pay for it.” One classmate, a Canadian citizen and US green card holder joked, “I keep my Canadian citizenship for a Get Out of Jail Free card. If I get cancer, I’m packing my bags and heading to Canada.”
I shadowed my physician mentor for an afternoon. It was a busy day so he saw some patients without my assistance. In 4 hours, I saw 7 of the 14 patients. The first patient was a 45-year-old gentleman, overweight but certainly not obese, presenting for follow-up after hospitalization with a transmetatarsal amputation (TMA). He was in disbelief after losing half of his left foot (including the toes) due to a foot ulcer. The physician delved into how he was managing his diabetes. His last sugar readings were off the chart and from over a year ago. He had not been taking his medications for several months. “It was too expensive,” he explained. This was typical of our patients who make too much money to qualify for Medicaid, but not enough to afford Obamacare health insurance. Our patient’s motivation: “I will do anything you tell me. Just let me have two legs when I see my thirteen-year-old son graduate college.”
The next patient was a thirty-year-old mother presenting for follow-up for a prescription opioid refill indicated for joint pain. We informed her that the state has a new law requiring an annual recreational drug test for prescription opioid recipients. She responded, “Yeah, I smoke weed.” She will come back in six weeks for her drug screen. The physician told me that this doesn’t always work out: “One of my patients failed the drug test for marijuana. I gave him a second chance six weeks later. He remarkably tested clean for weed… but positive for cocaine.” He did not get the refill. My attending also mentioned that these new rules will be costly for patients. “Insurance companies generally do not pay for drug screening. Patients have to pay $200 out-of-pocket unless they’re on Medicaid.”
The next two patients, a 40-year-old man and a 70-year-old woman, both presented for follow-up due to chronic obstructive pulmonary disease (COPD). Both smoked a pack a day. The doctor told each, “If you keep this up, you will eventually be on oxygen.” Both had
Full post, including comments