From our anonymous insider…
We had a week off. Several classmates visited girlfriends, boyfriends, and family. One went on a Caribbean cruise. A few stayed in town to recuperate and study this next block in advance (“gunners” is the class label for this behavior).
We’ll study neurology for the next two months, but class began with two deans reprimanding us. “It has come to our attention that several doctors and professors think you need to work on professionalism. Several of you are on Facebook, browsing Amazon, and checking Instagram during lecture while you sit next to a physician. SnapChatting in class is inexcusable. These physicians frequently volunteer their time to come in and speak to you. Treat them with respect. Every class gets a reputation. Don’t let this be yours.”
For eight weeks we will be taught almost exclusively by a 74-year-old neuroanatomist, “Doctor J”. He worked for several years as a physical therapist, then earned a Ph.D. in neuroscience. His first slide was a quote from Emerson Pugh: “‘If the human brain were so simple that we could understand it, we would be so simple that we couldn’t.” “We will do our best,” explained Doctor J. His second slide was a black and white photo of an old guy. “Neuroscientists bow before Cajal.” In the late 1800s there was no consensus on the anatomy of the nervous system. Two luminary anatomists, Camillo Golgi and Santiago Ramón y Cajal, supported opposing viewpoints. Golgi supported the reticular theory: nerves are a syncytium of several cells connected together. Cajal supported the neuron theory: each nerve is a single cell. Cajal used Golgi’s own staining method to disprove the reticular theory. This history lesson gave a human spin to the evolution of knowledge. These men worked in shoddy laboratories with microscopes that we could build today out of paper and tape.
We had to purchase several tools for the neurological exam, including a reflex hammer, pen light, and eye chart. Our white coat is filling up with gadgets! We will practice the exam in several workshops. Students complained to the dean about Doctor J not posting answers to the workshop questions. The neuroanatomist responded during lecture, “This is your fault. The first few years we did give out answers for the lab book. I put a copy in the library. Within a week, someone had photocopied it and send it as PDF to the whole class. The value of the workshops went down, no one attended, so I no longer give the answers out.” Apparently not all classmates were mollified by this explanation because enough students went back to the dean that he submitted a “formal grievance” against Doctor J.
Lecture began with an overview of the nervous system, divided into a central nervous system (CNS) and peripheral nervous system (PNS). The CNS is a tube with a hollow canal in the middle where cerebrospinal fluid flows. This tube is simple in the spinal cord but becomes suddenly more complicated at the top of the tube, which will become the brain. During fetal development (in utero), the cells of this part grow much faster than the surrounding skull causing bending and folding of the tube. The brain retains its lumen (inner membrane adjacent to canal) as the four ventricles of the brain that are continuous with the central canal of the spinal cord.
Unbeknownst to me, the spinal cord does not extend the whole length of the spine. Before birth, the spinal cord extends to each vertebrae. However, during childhood the vertebrae elongate faster than the the spinal cord, resulting in the spinal cord’s termination at the first or second lumbar vertebrae (above the hip bones). A lumbar puncture (“spinal tap”), a common procedure to sample cerebrospinal fluid, leverages this anatomy by sampling the cerebrospinal fluid at L4 without the risk of puncturing the spinal cord.
There are about 860 billion cells in the brain, only 10 percent of which are neurons. Ninety percent are supporting cells called glia and microglia. These cells perform various functions: astrocytes (a type of glia) maintain the blood-brain barrier by wrapping foot processes around ninety-five percent of the capillary surface area (it reminds me of the scintillating podocytes in the glomerulus of the kidney); oligodendrocytes (a type of glia) insulate the axon cable (wire to the next neuron(s)) by wrapping sheaths of their cytoplasm around the cable; microglia are specialized resident macrophages that get in the central nervous system in utero before the blood brain barrier is formed.
Myelination is essential for neuron function. The conduction velocity of the action potential (the nerve signal) decreases as the resistance of the axon cable increases. Organisms such as the giant squid without myelinating cells achieve high transmission speeds by having huge axon diameters. Myelination decreases the effective membrane capacitance, which reduces the amount of potential needed to charge up the axon, and decreases potential leakage. Myelination enables the preservation of high speed as more neuron connections are packed into a small volume. This is important because intelligence is related to the connectivity (or synapse density) of each neuron. A human brain is estimated to contain more than 100 trillion synapses for roughly 86 billion neurons.
We learned how the number of cells change during human development. Between the third week and twenty-eighth week after fertilization, 250,000 brain cells are produced every minute! Many of these neurons undergo apoptosis (cell suicide) during training of the neural network. Despite this amazing proliferation, the brain is only twenty-five percent of its adult size at birth; the brain reaches seventy-five percent of its adult size at one-year of age.
In my small group we discussed foundational neuroanatomy structures. The corpus callosum is a bridge for nerve fibers to cross between cerebral hemispheres. Someone mentioned the corpus callosum is thicker in females. A question “Is this why women are more emotional?” yielded chuckles from several male students and glares from Type-A Anita and straight-shooter Sally. Anita replied, “Yes, that is exactly why. It’s going to be a long two months with you guys.”
Anatomy held a dry lab in which we felt bone vertebrae. Dry vertebrae (just the bones) have spinous processes which look like something out of a Game of Thrones episode. The spikes you can feel on your back are these spinous processes. The vertebral body, the main weight-bearing part, lies deep to this on the anterior (front) side. The spinal cord sits between the vertebral body and the spinous process inside the vertebral foramen (hole). The spinal cord gives off spinal nerves through the small bilateral intervertebral foramen. We saw how the intervertebral facet joints differ among the cervical, thoracic, and lumbar (neck, chest, and lower back) regions. The cervical vertebrae have the joints in the axial (horizontal) plane facilitating rotation; the cervical have the joints in an oblique plane preventing significant movement here; and, the lumbar vertebrae have their joints in the sagittal (vertical side section) facilitating forward bending and extension.
Our patient case: Jonathan, 25-year-old male presents to the ED nine months ago for a three-minute seizure and worsening headaches in the morning for the past month. A neurological exam shows absence of venous pulsations, suggesting elevated intracranial pressure. Jonathan did not pay much attention to the headaches. He was busy at work, and his wife was due with a second child.
A CT (“CAT scan”) revealed a 3x3x3 cm (a little more than a cubic inch) tumor in the right temporal lobe of the brain. Surgery was scheduled immediately. The neurosurgery team debated removing the entire temporal lobe or just a “lesionectomy” where they remove the tumor with as good margins as possible. A lesionectomy was performed and a pathology analysis of some of the tumor removed revealed a grade III glioma. Jonathan’s neurosurgeon told us that “All grade III gliomas eventually become grade IV.” A death sentence. Jonathan is still alive, nine months after his first ED visit, but was unable to attend due to worsening health.
According to the neurosurgeon, a patient presenting to the ED with a headache will always get a head CT. However, it is unlikely the same patient’s primary care doctor will order a head CT for just a headache.
How many patients with advanced brain cancer elect not to get surgery? “Much more rare than you would expect,” responded the neurosurgeon. “Everyone hopes they will be the exception, the extreme outcome. We hope for a cure, so our treatment plan is very aggressive.” He has operated on a 86-year-old with grade IV glioma (the patient died; Medicare paid the bill). He recounted a troubling story of a 60-year-old late stage Huntington’s patient with glioblastoma. “His wife had a very difficult time letting go. We said we could get him back to baseline, but that baseline was late stage Huntington’s. They decided to not operate.”
What’s more important for neurosurgery, dexterity or knowledge? “We can teach a monkey to do surgery in seven years. Passion is the most important quality. I see senior residents get angry at newer residents because they work shorter hours than they did. They are bitter, and remorseful. Unless you have the passion, you will burn out.” He joked that sometimes beginners can be too passionate. “One of my residents got so excited about a successful shunt [apparently, a common neurosurgery procedure] he performed. It’s not that big a deal, we do shunts every damn day. I did not want to burst his bubble so I told him ‘Great job!’… Don’t tell him I said that!”
How did he cope with such depressing cases? “It is tough. I see cases like Jonathan’s every month,” he answered. “Everyone manages it differently. For me, as long as I feel like I treated my patient and their family like my family, I sleep fine. It is when I remember at night that I forgot to talk to that family member that it hits me.”
A seventy-year-old dermatologist with a strong southern accent held a lunch session to explain why his field is the best: “I cannot think of a single reason why you would not want to do Derm. It pays well. It has unbeatable hours. The patient population is generally quite motivated to get better.” He was in private solo practice for much of his career. “Many of my patients, such as lawyers, paid cash.” A classmate asked, “Did it get lonely working solo?” He responded, “No, we have nurses.” He described how there are just not many dermatologists, claiming this was the reason why there were so few dermatology residency slots. Dermatology is one of the most competitive residency programs.
Friday was Match Day, a slight misnomer because it is one day after fourth-year medical students hear where they will (or will not) be completing residency. Students and residency programs rank their top choices. Almost 36,000 domestic medical students and international doctors vied for about 29,000 residency slots. Fifty percent of applicants nationwide got their first choice.
The whole school attends the ceremony. Each student goes up to the podium and says something like “I will be will doing Internal Medicine at the University of Southern California.” Fifteen percent of the class couples matched. Two individuals need not be married or in the same specialty to couples match. An orthopedic surgeon sent an email out congratulating the class on their impressive Match Day results, but reminded the first through third year students not to slack off. He ended with a quote from Will Rogers: ” Even if you are on the right track, you will get run over if you just stand there.”
Statistics for the week… Study: 10 hours. Sleep: 7 hours/night; Fun: 2 nights. Example fun: A good friend and former coworker visited for the weekend. We joined Match Day celebration at a pregame followed by a late bar night filled with plenty of Guinness for Saint Patrick’s Day. Jane and I saw Beauty and the Beast on Sunday evening.
“Students complained to the dean about Doctor J not posting answers to the workshop questions … Apparently not all classmates were mollified by this explanation because enough students went back to the dean that he submitted a “formal grievance” against Doctor J.”
Really? what happened to understanding the material. Makes me afraid to know what medicine will be like in a few decades. Maybe like this scene out of Idiocracy: