What do donkeys, horses, and zebras have to do with teaching medical students and residents about medical diagnosis? A former medical student recently thanked me for teaching him about how sounds in the night can teach medical students about making diagnosis. Almost 40 years ago I was a beginning third year medical student at Harvard where whenever we were presented with a case we often immediately jumped to the conclusion that the cause was some fascinating albeit rare condition.
One day early in my first year of clinical medicine we were on rounds when the professor when presented with the “fascinoma” asked our small group on rounds with him this question.
“When you hear hoof beats in the night do you think it is a zebra or a horse?”
What is the animal that comes to mind when we hear hooves clamoring in darkness ? How we identify by sound the clamoring hooves of an unseen animal in the darkness can help teach medical diagnosis to medical students. Well since we were in the United States where there are many more horses and few zebra we would respond accordingly. This demonstrated to us that common things occur more ofttimes then the rare. There are likely at least tens of millions of donkeys in use in Ethiopia in almost every rural home whereas horses are present but used to a much lesser extent.
Now take us almost 40 years later where I have been teaching medical students and neurosurgery residents over the past ten years in Ethiopia. This analogy is not only useful for teaching the commonality point but also for teaching that different countries may be different in what occurs. For example Ethiopia has a high incidence of tuberculosis.
Similarly Ethiopia has its own breed of donkey called the Abyssinian donkey which is the daily mode of transporting materials for many Ethiopians. They have horses but to a much lower extent then the donkey. Additionally both Kenya and Ethiopia have the Grévy’s zebra which is the largest animal in the horse family and endangered.
Different countries may not only have different relative levels of different diagnosis but also diseases that are more unique to their population then in other countries. Many times students and resident will present medical research published from the USA or Europe with discussions of incidence, treatment, and characteristics of a malady. Again we can use the donkey, horse, zebra analogy to make the point that medical disorders may have not only different levels of occurrence in different countries but also different presentations.
Very few times in the history of medicine has one man so dominated the development of a specialty that his birthday is celebrated as the day to recognize the field but that is case in Neurosurgery. The legacy of Harvey Cushing connects Ethiopian neurosurgery to his life’s work. When I entered Harvard Medical School in the Fall of 1977 I knew was interested in the field of neuroscience but I did not at first understand how I had entered into the hallowed historical grounds where Harvey Cushing made so many advances.
Harvey was destined to be a fourth generation physician who began his studies at Harvard Medical School after undergrad at Yale just before the beginning of the 20th century. After graduation in 1895 he and Ernest Codman pioneered physiologically monitoring in anesthesia which dramatically reduced the previous death rates. Subsequently he trained in general surgery at Johns Hopkins under William Halsted, the great pioneer of modern general surgery. Residency training at Hopkins was scientifically driven by William Osler who also mentored Cushing leading him to write a biography of Osler in 1926 which won a Pulitzter prize.
From 1902 to 1937 first at Harvard, then Hopkins, and finally at Yale, Cushing performed over 2000 operations of the brain pioneering surgical techniques for the treatment of brain tumors. He revealed how the physiology of the brain functions in terms of blood pressure and brain perfusion and how the pituitary gland works. Brain surgery went from being a last chance high risk procedure to having the ability to safely save lives through out the world because of his influence and teaching.
As a medical student at Harvard I saw patients on the grounds where Cushing lectured and went to operating room where Dr. Cushing performed brain surgery. I was fascinated and inspired by the life of Dr. Cushing and this experience in my early years led to my doing a special training in neuroscience as a medical student and then to train in neurosurgery after graduation.Later as resident in Neurosurgery at the University of Miami, Dr. Larry Page, who was trained at Harvard and the Boston Children’s Hospital by neurosurgeons who trained under Cushing , was our main brain tumor training surgeon.
Six years ago I started the Neurosurgery program at Ayder Comprehensive Specialized Hospital-Mekelle University in Ethiopia where today we perform over 1000 operations a year. We currently are training 16 neurosurgeons for different regions in Ethiopia as well as Somaliland and Somalia. Following Cushing’s model of a neurosurgeon who cares about the world and his patients and uses the scientific model of research to improve life, we have created a multidisciplinary research team which has made significant discoveries in the epidemic of neural tube defects in Ethiopia. Our research led to the government studying a novel prevention program of fortifying salt with folic acid.
Happy Birthday to Harvey Cushing you changed the world and helped inspire a kid from a small town in Texas to follow your example.