How Much Knowledge Does a Neurologist Need?

October 9, 2009


hierBy Daniel B. Hier, MD, MBA, FAAN, Education Editor

In 1886, Leo Tolstoy completed a short story entitled "How much land does a man need?" The protagonist of the story, a peasant named Pakhom, complains that he does not have enough land. He eventually comes to the land of the Bashkirs, who offer him an unusual bargain. For 1,000 rubles, he can have all of the land that he can encircle within a single day. The proviso is that he must return to his starting point by sunset or he will be awarded nothing. In his greed, Pakhom sets out to cover too much land.  He eventually reaches his starting point at sunset in a state of exhaustion, whereupon he dies.

As neurologists, we face a huge expanse of knowledge, far more than we can encircle in a lifetime. Each day, that vast expanse of knowledge grows ever larger. Like Tolstoy's Pakhom, we must make a calculated decision as to how much knowledge we can encircle without dying of exhaustion.

The Scope of Neurology

In 1977, when I was in my last year of neurology residency at Massachusetts General Hospital (MGH), Raymond D. Adams, MD (1911–2008) published the first edition of his classic textbook Principles of Neurology.1 Adams largely wrote the book by himself, aided in a few chapters by Maurice Victor, MD. As residents we were dazzled that our Chief could master the entire breadth of neurology alone. Adams wrote about each disease convincingly, evoking a sense that he had personally diagnosed and treated each condition within his text. As residents we joked among ourselves that Adams was likely the last living neurologist to know "all of neurology," and probably the last living neurologist capable of writing a comprehensive textbook of neurology single-handedly. Since Adams finished his textbook, neurology has become ever more complex, with the result that no one individual can ever again hope to be the master of all neurologic knowledge.

No adequate measure exists to estimate the vast scope of neurologic knowledge. As a proxy for the size of the knowledge base of neurology, I searched MedLine (1996–2009) for the terms "dementia" (56,953 articles), "cerebrovascular diseases" (110,214 articles), "epilepsy" (45,589 articles), "multiple sclerosis" (17,471 articles), "neuropathy" (22,119 articles), and "headache" (8,260 articles). These numbers just hint at the huge bulk of available neurologic knowledge.

What Does It Take to Be an Expert?

Herbert A. Simon (1916–2001), winner of the Nobel Prize in Economics, addressed the question of how much knowledge experts possess. Based on a study of chess grandmasters, Simon estimated that each possessed at least 50,000 "chunks" of knowledge stored in memory. For knowledge-rich fields of study, Simon argued that experts require at least this number of discrete bits of knowledge. Simon wrote that "no one knows everything there is to know about chess, medicine, chemistry, or any other serious domain….A professional's knowledge is adequate when he or she knows about as much as other professionals in the same discipline."2

Simon believed that the duration of our lifetimes puts a limit on what we can learn. He estimated that even if we learned a new chunk of information every 10 seconds and worked 3,500 hours per year studying for 10 years straight, we could master 12.6 million chunks of information, a prodigious feat but one unlikely to be accomplished by any one neurologist.

Just-in-time Knowledge

Just-in-time inventory is a concept derived from operations management. Businesses find it more efficient to have on hand only the inventory that they need at a given time. These businesses develop rapidly responsive supply chains that deliver inventory to them as they need it.

Similarly, as neurologists we need just-in-time knowledge. We should have on hand the knowledge we need to do our everyday work. But we also need rapidly responsive supply chains of new knowledge to deliver the essential knowledge that helps us take care of our patients as the need arises. It is simply impossible to master in advance everything we could possibly need to know. Instead of following this impossible model, we should become nimble users of neurologic knowledge and acquire it rapidly as the need arises.

Twelve Easy Steps to Acquire Just-in-time Neurologic Knowledge

  1. Use's search engine search window The Academy's website offers an abundance of knowledge, including the practice guidelines, articles from Continuum: Lifelong Learning in Neurology®, articles from Neurology®, and contributed documents and articles. A powerful search engine helps you find relevant documents.

  2. NeuroSAETake the NeuroSAE™
    The AAN's online self-assessment examination in clinical neurology, NeuroSAE™, covers 20 areas of neurologic knowledge. Use the test to find the gaps in your knowledge, or find reading suggestions by topic area. NeuroSAE helps you create your own knowledge profile (i.e., "what you know and what you don't know").

  3. NINDSShare the Disorders Index with your patients
    The NINDS Disorders Index is now available on and (the Academy's public education website). Save the links to these disorders in your web browser and share them with your patients.

  4. Get a document scanner
    I use a document scanner with my computer to virtually eliminate paper in my home office. I use a sheet-fed scanner (for example the Fujitsu S1500M is about $400) with a 50-sheet automatic document feeder (ADF) to convert all my paper into searchable PDFs (portable document format files) on my hard drive. This way no document is ever lost, everything is indexed, and filing is a breeze.

  5. Get a smartphone
    I forward my email, faxes, and voice mail directly to my iPhone so they are all in one place and always with me. I keep my calendar on Google Calendar, but sync it to my iPhone so that it is always with me and synchronized with each computer I use. There are a growing number of knowledge-based apps for the iPhone, including ICD-9 guides, E&M coders, an eye chart for testing visual acuity, the NIH Stroke Scale, the Glasgow Coma Scale, and drug prescribing guides.

  6. Take advantage of the cloud
    One way to take advantage of "cloud computing" is to store important files on the Internet at hosted sites; these areas are accessible from whichever computer you use, wherever and whenever you need them. I have placed key documents that I commonly need in the "cloud" for easy access. For example, I keep a handicapped license plate application form on a free website I created using Google sites, which allows me to download the form whenever I need it. Another option for Mac users is the cloud created by Apple called Mobile Me.

  7. Use images to educate your patients
    I use images from Google Images to educate my patients. For example, if I have a patient with meralgia paresthetica, I can quickly find an image of the lateral femoral cutaneous nerve via the simple search interface. (In a previous article, I provided an in-depth overview of how to find neuroimages on the Internet.)

  8. Put a computer in each examination room and get an electronic health record
    We currently use a computer in each examination room to document patient care with an electronic health record. In addition, since there are computers in each room we can use the Internet to quickly access knowledge relevant to each individual patient. Electronic health records will soon evolve so that accessing knowledge, care guidelines, and decision support are seamlessly integrated within the patient care process.

  9. Become expert with a good online medical literature search engine
    Facility with a good online medical literature search engine is key to rapidly accessing knowledge relevant to your patient. Neurologists affiliated with large hospitals or universities are likely to have easy access to either the Ovid or MDConsult medical literature databases. Unaffiliated neurologists can get free access to MDConsult through the excellent MerckMedicus website. These are powerful search engines, but obtaining good results depends on devoting some time and energy to familiarizing yourself with their power…and their idiosyncrasies.

  10. Build an educational portfolio and track your progress offers an excellent tool to track both AAN and non-AAN CME credits. You can use this tool (My CME Transcript) to track your educational activities and generate an enduring record.

  11. Buy an external hard drive
    You can buy a one-terabyte (1,000 gigabyte) external hard drive for under $100. This piece of hardware plugs directly into your desktop or laptop computer, storing or backing up everything on your computer's hard drive. Save all your files, images, and documents on your hard drive, then search for them when needed. (Note: It is estimated that only 10 terabytes are needed to store all 29 million volumes in the Library of Congress.)

  12. Know how to search your computer
    If you have stored many documents on your computer, you need a way to easily retrieve them. Both Windows-based computers (Windows Search) and Mac-based computers (Spotlight) have powerful search engines built into the desktop. With these tools, you can find every document on your computer with ease.
  13. Back to top.


  1. Adams RD, Victor MA. Principles of Neurology. New York: McGraw-Hill, 1977.
  2. Herbert Simon. The Sciences of the Artificial. Cambridge: MIT Press, 2nd Edition, 1981; p. 107.

Author Disclosure

Within the past 24 months, Dr. Hier received compensation for medical legal consulting. In the same period he gave expert testimony in medical malpractice cases.