What Sciences Constitute the Foundation for Medical Practice?
The Flexner Report clearly showed the practice of medicine has its foundation in the basic sciences. Empirical observations gave way to scientific inquiry as technological advances took place. Anatomy, chemistry and physiology can, arguably, be considered the original basic sciences that spawned histology, biochemistry, cell biology, microbiology and pathophysiology. More recently, pharmacology and the rapidly expanding field of genetics are now considered essential basic sciences for the study of medicine. Neuroanatomy is a traditional basic science that was a natural outgrowth of the study of gross anatomy. The authors recognize that since the 1970’s many medical “neuroanatomy” courses have transformed into “neuroscience” courses that incorporate new found knowledge derived from immunohistochemical and molecular techniques. Therefore, the traditional neuroanatomical study of spinal cord pathways, the brainstem, cerebellum, diencephalon, basal ganglia and specialized cortical functions is now supplemented with our growing molecularly-based knowledge of neurotransmitter and receptor functions and their interactions with newly developed pharmaceuticals. As shall be mentioned later, a neuroanatomy course that is heavily weighted towards neuroscience does not necessarily benefit the undifferentiated undergraduate medical student.
What is the Value and Role of Foundational Sciences in Medical Education?
This fact was firmly established 100 years ago by Dr. Flexner and is still valid for the future of medicine. Although neuroscience research is rapidly advancing our knowledge base, there is still a need for traditional neuroanatomy to be a substantial part of any “neuroscience” course. As an organ system that pervades the entire body, it is sine qua non neuroanatomy be a part of any medical curriculum. Furthermore, the study of neuroanatomy promotes the development of deductive reasoning skills that are needed to practice medicine, because basic neuroanatomical knowledge, without the use of CT scans or MRI, can still be used to determine the site of a central or peripheral nervous system injury. Perhaps even more important, deductive reasoning can be used to decide if a set of symptoms and signs are explained by a lesion seen on an imaging study.
To date, most of the advances in neuroscience knowledge, other than some of the pharmaceutical aspects, have yet to be translated into bedside practice. Despite the large amount of neuroscience research being performed (the 1990’s were even declared “The Decade of the Brain”), the central nervous system (CNS) continues to resist efforts to reverse spinal or cortical injuries and CNS repair remains enigmatic. Neurologists and neurosurgeons, even though they now have the ability to visualize CNS anatomy more clearly than ever via CT, MRI and fMRI techniques, are still frustrated in their inability to offer effective treatment for many patients. However, the future holds much promise as our fundamental understanding of so many previously untreatable diseases, e.g., multiple sclerosis and Parkinson disease unfolds from the weight of millions of research dollars.
The topic of neuroscience can be introduced at any point during the first two years of a four-year medical education, or early in year three of a six-year curriculum. Since this topic constitutes a complete organ system, it can be a stand-alone course in medical schools that have a “traditional” discipline-based curriculum, as well as in those that use an integrated or organ system-based curriculum. The length of neuroscience courses in the United States varies from a full 18-week semester, where it is taught concurrently with three or more other courses, to an eight-week full immersion course usually running concurrently with an “art-of-medicine” course, e.g., introduction to clinical medicine or physical diagnosis.
Ideally, a neuroscience course should partially overlap with a gross anatomy course. Simultaneously teaching the head and neck portion of gross anatomy while the neuroscience course is presenting the brainstem makes for an integrated approach to learning cranial nerve function. This method eases the student’s ability to take the peripheral/functional aspects of cranial nerves, taught in gross anatomy, across the subarachnoid space into the brainstem where the neuroscience course presents the typical strokes that impair cranial nerve function. This approach greatly enhances the integration of the two courses. In addition, neuro-histology, -embryology, -radiology and -physiology can be incorporated into the neuroscience course at the appropriate points to help the student integrate these disciplines with the nervous system. In some medical schools, behavioral science is also taught as a part of a neuroscience course; if this is the case, the hybrid neuroscience course is usually presented early during the second year of a four-year curriculum.
The authors have found that even before a neuroscience course has started, presenting clinical scenarios involving peripheral nerve injuries during the extremities portions of a gross anatomy course sets the stage for the study of the CNS. All too often, peripheral nervous system injuries are left to the purview of gross anatomy courses and texts, and are not adequately covered in neuroscience courses and texts. It is important to recognize that the peripheral nervous system should not be ignored in a neuroscience course, since reviewing typical peripheral nerve injuries reinforces the neurology concepts needed for passing medical board examinations and, more importantly, makes for a more competent medical resident and physician.
Probably more than most basic science disciplines, the study of the nervous system lends itself nicely to teaching via clinical scenarios. The somatotopic organization within the central nervous system allows logic to be applied in determining the site of a lesion or the functional deficit resulting from a central or peripheral nervous system injury. Knowledge gained from a neuroscience course can be directly applied to clinical scenarios, even before the medical student has had exposure to their clinical rotations, since the student should have acquired the ability to diagnose common CNS or peripheral nervous system injuries.
What Sciences should be a Prerequisite of a Pre-Medical Curriculum?
Although many of the basic sciences have a foundation course presented at the undergraduate level, e.g., biochemistry, cell biology, physiology, histology, genetics, and, occasionally, comparative anatomy, there are not as many universities that have an undergraduate neuroanatomy/neuroscience course. If it is offered, the subject is usually taught from a neuroanatomical approach. (It should be noted that many universities offer a variety of graduate neuroscience courses.) Is an undergraduate neuroscience course necessary for success in medical school? That is difficult to determine. The opinion of the authors is “no”, since a medically-oriented, neuroanatomical approach to the subject is not conceptually difficult, and “lesion hunting” is a logical process that can be easily grasped by the highly motivated medical students. If a medical neuroscience course is more molecular-vs. anatomical-based, the prevalence of undergraduate cell biology and biochemistry courses should provide a sufficient background to apply the concepts to the nervous system.
The experience of the authors shows that what’s lacking in many medical matriculates is a basic knowledge of cranial nerve function and head and neck embryology that would make understanding the brainstem unit of a neuroscience course easier to grasp. Therefore, a robust undergraduate comparative or human anatomy course would be more beneficial to a greater variety of health-related professions students than a neuroscience course whose approach is more molecular in nature. Furthermore, an embryology course, that is classical vs. molecular in nature, would not only teach how the dermomyotome is formed and is inexorably linked to it’s spinal nerve, it would also teach brachial arch formation and their cranial nerve supply. Another added benefit of studying classic embryology would be the study of sectioned material, e.g., the 10mm pig embryo, so that students have practice in mentally forming three-dimensional reconstructions. Experience in using the “minds eye” would be of great benefit when medical students, residents and physicians examine CT scans and MRI’s.
What Are the Best Practices for Placing Foundational Sciences into the Medical Curriculum?
There is probably no other basic science course that has a more varied curriculum in medical schools around the world as a neuroanatomy/neuroscience course. The gamut ranges from solely a traditional neuroanatomical approach, to a mainly neurophysiological/molecular approach, with any blend of these two extremes. The large number of texts whose content ranges from basic neuroanatomy, to clinically-based applications, to molecular/physiologic approaches attest to this. Over the past two decades, the basic neuroscience concepts needed to prepare a well-trained, undifferentiated, undergraduate medical student has been eroded by an approach to the subject that is too in depth and geared more for graduate students than medical students. The authors feel this too detailed approach to the material is more prominent in neuroscience than most other basic science fields. Therefore, in order to prevent the continual addition of large amounts of new content, neuroscience course directors must avoid adding additional information to their courses that is not clinically applicable at the current time. Until there are major breakthroughs in translational neuroscience research, knowledge of complex molecular events can’t save a patient’s life.
Unlike gross anatomy courses, it is not essential that the anatomical aspects of the nervous system be taught using cadaveric material. There are numerous neuroanatomy atlases that provide the images necessary to learn CNS anatomy. Furthermore, images of cadaveric material are now supplemented with CT scans and MRI images that give the undergraduate medical student an excellent exposure to neuroradiology. Laboratory sessions for neuroscience courses should, ideally, be organized around a neurosystems approach that uses clinical cases to reinforce the didactic portion of the course. For example, Radiology faculty and residents can present clinical cases using CT scans and MRI’s. Pathology faculty and residents can bring neuropathological specimens to present an introduction to neuropathology and provide visual reinforcement for the various lesions that produce CNS deficits.
Neuroscience has an advantage over most basic science courses in that it can be taught almost exclusively from a clinical perspective. Once students have mastered the basic neuroanatomical pathways, cortical regions and CNS blood supplies, a functional deficit can be presented to students for them to localize the lesion within the central or peripheral nervous systems and vice versa, a nervous system lesion can be presented to the student and they can describe the functional deficit. The authors feel it is imperative that any neuroscience/neuroanatomy course be presented from a clinical approach so that a general practitioner can know when to triage a patient and send them to an emergency department or trauma center. It must also be remembered that only a small percentage of medical students select neurology or neurosurgery as their residency choice. Therefore, it is even more important to teach the subject from the perspective of what is needed by a primary care physician and not a neurologist, neurosurgeon or graduate student.
Another way to consolidate neuroscience knowledge for medical students is to have patients presented during Neurology Grand Rounds that have ”classic” neurological problems that can be understood by freshmen medical students, e.g., upper or lower motor neuron lesions, Parkinson disease, or Horner syndrome. During the presentation the neurologist can explain the reasoning and tests ordered based on the differential diagnosis, while the neuroradiological and neuropathological aspects of the case can be presented by a radiologist and pathologist. Seeing these patient presentations literally brings neuroscience to life and is readily appreciated by the medical students. If live patients can’t be used, then videos of patients can be provided (only if the patient has signed the appropriate consent forms!). Our experience supports live patients as a far superior learning experience, especially when a clinician takes on the challenge of seeing the patient with an unknown problem in front of the medical students. The physician/patient discourse on how the patient history and physical exam leads the clinician to localize the lesion and obtain the diagnosis reveals to the students the logic of the clinician’s thought process.
Testing the student knowledgebase is important and examinations should preferably use clinical scenarios. Short National Board of Medical Examiners (NBME)-or United States Medical Licensing Examination (USMLE)-style vignettes can be written that use only prose or are supplemented with a neuroanatomical or neuroradiological image. Using this method of testing helps ensure you are gauging the depth of student understanding vs. their ability to regurgitate memorized facts.
In the United States, the USMLE and American Association of Medical Colleges (AAMC) want to blur the artificial split between the basic sciences and clinical rotations. Medical curriculum committees need to determine ways the basic sciences can be reinforced in the clinical years, and more clinical exposure provided to freshmen and sophomore medical students. It has already been mentioned that it is relatively easy for patients with classic neurological deficits to be presented to first and second year medical students during Neurology Grand Rounds or other clinical sessions within the neuroscience course. Placing neuroscience material into the third and fourth years of medical school, without occupying an inordinate amount of basic scientist time, can be accomplished by providing video recordings of essential or confusing neuroscience topics (e.g., spinal cord pathways, autonomic nervous system function, the pyramidal and extra-pyramidal motor systems) that can be viewed by the junior or senior students during their neurology and/or neurosurgery rotation. Neuroanatomical topics would not need updating once a perfected presentation is archived, but neuropharmacological topics would require updating as new breakthroughs in treatments become available. Furthermore, the use of on-line neuroscience-related resources, e.g., MedEd Portal (managed by the AAMC) could be accessed by medical schools around the world. It is critical that this information be primarily review material and not new basic science information for the students. For instance, students in the clinical years have to learn the intricacies of treating strokes and facial nerve palsies, and if they have not learned to recognize them beforehand, the task will be overwhelming.
Finally, the authors are concerned about who will be qualified to teach the fundamental sciences in the near future. Now that many Ph.D. graduates have been trained in molecular techniques, there will be a natural desire for these new faculty to teach the neurosciences within their comfort zone of using a molecular approach to the subject and, unfortunately, sometimes overemphasizing their area of research. It is not unusual to receive neuroscience course evaluations where students state that many of the lecturers talked more about their research interests vs. adequately covering the lecture objectives. This problem is not unique to neuroscience since it’s happening in many other basic science fields, e.g., physiology. The problem will continue to grow in the United States and, perhaps, other countries because there are few new Ph.D. graduates who have a comprehensive understanding, or even a basic overview, of their discipline. So it is critical at both the local and national levels to have clinicians and basic scientists work together to fashion the best framework to educate our future clinicians in neuroscience. Only together can we strike the best balance of what they need now and what they may need to know in the future as research leads to new treatments.