Interactive Large Group Lecture Demonstrations: Dramatization of Medical Neurobiology Concepts to Improve Student Perception of Understanding Fluid Mechanisms of the Central Nervous System

Abstract

With the advent of recorded lectures, face-to-face teaching in medical school large classroom settings is increasingly under pressure to incorporate engaging activities that encourage attendance and can translate to greater attainment and long-term retention for learners, especially of “Generation Z” learning styles. This places a greater onus on lecturers to convey key concepts in a manner that holds value beyond their recorded substitute. The present article details several on-stage Medical Gross Anatomy and Neurobiology demonstrations that involve the teaching of an intuitive understanding of brain fluidic mechanics, such as hematoma formation and the protective functions of an intact cerebral spinal fluid system (addressing concussion and lumbar punctures). These demonstrations can be presented relatively quickly on stage and are suitable for engaging large classroom sizes (n > 100), which can be used in conjunction with traditional lecture formats. Ideally, these in-class demonstrations, together with the continued contributions of other quantitatively assessed demonstrations from other institutions, will help to maintain a growing body of large class face-to-face teaching approaches and strategies to help influence decisions regarding what basic medical knowledge may best be taught in class live versus by recorded substitute or other non-traditional lecture methods.

Appendices

Appendix 1

Title: Epidural Hematoma Formation: “The Baseball Bat Accident”

Estimated Time: One 10-minute session.

Lesson Author: Dr. James W. Lewis, PhD, West Virginia University Department of Neuroscience.

Learning Objectives:

• 1. Describe the mechanics of how an epidural hematoma forms.

• 2. List and explain key anatomical structures, including the pterion, middle meningeal artery, foramen spinosum, dura mater, arachnoid mater, extravasation.

Resources & Materials, (also see Fig. 1)

• One 3x3 feet sheet of white, hard, waterproof foam padding to simulate a piece of curved skull over the pterion

• One transparent, colorless shower curtain

• One tube of watertight sealant. Roughly, 5 feet of red colored PVC tube with a funnel and stopcock (available at most party stores)

• One children’s plastic baseball bat

• One gallon and one ½-gallon milk container filled with water and red food dye (to simulate blood)

• One 2x4 foot under-the-bed storage unit (to capture any leaks and to store materials)

Preparation

• 1. If your classroom does not have space for the demonstration, arrange for class time in another room.

• 2. Labels can be placed on the model, including the “pterion”, skull sutures, “foramen spinosum” where the red tube (middle meningeal artery) penetrates the skull (Fig. 1) before class.

• 3. Between the shower curtain and foam, slide in one red tube and add split (bifurcation) of tubing for an anterior middle meningeal artery and a separate piece or two of tubing to show a “rupture” of the artery—this is hidden from audience’s view until after the “accident” occurs on-stage.

• 4. Provide safety goggles for the student swinging the bat, at least for dramatic effect. All wet items can be tossed into bin and quickly removed for later clean up.

• 5. Be sure to have a mop or towels on hand to clean up any fluid mess during break after class, and/or place a “caution” placard for additional dramatic effect. If the manipulandum leaks, use this to your advantage as a teaching moment to highlight a mix of epidural and subdural bleeding. Regardless of in-class outcome, the attempt of performing this demonstration will be remembered longer-term, while details can be read or referenced at a later time.

Instructional Plan:

• 1. Begin by selecting two students to hold the skull—one tall student to pour blood/water into tubing through funnel, and one student to swing the bat to simulate a baseball game “accident”.

• 2. Ask the student to swing the baseball bat towards the foam at the pterion (Fig. 1c), which is a weak point of human skull [24, 25]. Make sure this is loud and play up the drama to attain full class attention and anticipation.

• 3. Tell the students the following, “The middle meningeal artery has been ruptured. Predict what you think will happen next.” (Take a few predictions out loud.)

• 4. Next, have the two students turn the model around to reveal the ruptured meningeal artery (Fig. 1d)

• 5. Elevate the red tube with funnel and have a tall student pour in the blood/water. The shower curtain should hold and begin to fill creating a bi-crescent shape between the white foam/skull and dura mater/shower curtain.

• 6. After a gallon or so has filled, point out how in any plane of section a CT or MRI scan would show a bi-crescent shaped hematoma. The teacher will explain how this is a classical epidural hematoma. Note that if the shower curtain were to break/leak (a potentially humorous moment on stage), this would represent a subdural hematoma or a mix of the two (which actually is relatively common, but not as elegant to demonstrate or assess on Board exams).

• 7. Follow up the demonstration by showing CT or MRI scans of classical epidural hematoma relative to a subdural hematoma, ideally from required or suggested textbook reading assignments.

• 8. Invite students to discuss the demonstration with the follow up questions to assess learner understanding of material:

  • a. Explain why an epidural hematoma has a ‘bi-crescent’ shape?

  • b. What would a CT scan of a subdural hematoma look like?

  • c. Based off of this demo, describe how a hematoma might affect intracranial pressure?

STUDENT ASSESSMENT/REFLECTION

Students can be assessed through their in-class discussions and participation.

Appendix 2

Title: Cerebral Spinal Fluid (CSF) System Integrity

Lesson Author: Dr. James W. Lewis, PhD, West Virginia University, Department of Neuroscience.

Learning Objectives:

• 1. Describe the mechanics of how the CNS (brain and spinal cord) are effectively floating in the dura and skull/vertebrae.

• 2. Describe how the closed CSF-system affords protection from impact.

• 3. Explain the mechanics behind headaches formation resulting from CSF leakages, including a lumbar puncture.

Resources & Materials (also see Fig. 2)

Part A

• 1 white plastic bowl

• 1 Cordura bag

• 1 green sponge mop head

• 1 towel to clean up liquid

• Saran wrap

• Plastic brain model

• Document camera or device to view the demo throughout the classroom

Part B

• 1 red dyed, hard-boiled egg (from convenience store)

• Small glass jar with lid (to fit egg)

• Water plus 1-2 tablespoons salt (mix until roughly buoyant for egg)

Part C

• Floating sphere in fountain (desktop water fountain, available online, under $40)

• One surge protector with on/off switch and extension cord (Fig. 2c).

Part D

• One small transparent jar with lid, filled with tap water

• One raw egg

Preparation

• 1. If your classroom does not have a document camera already, arrange for the provision of one or some form of projection so all students can see it (Fig. 2a, c)

Instructional Plan: Part A illustrates an opened CSF-system, followed by Part B to illustrate mechanics of a closed CSF-system, can be implemented during one lecture using a document-camera to project the apparatus. Part C and D can be implemented during that lecture or on later lecture days/weeks, each time going out into the audience and engaging active recall.

Part A: How the CNS (brain and spinal cord) floats (~2 minutes)

• 1. Obtain a white plastic bowl (skull), with Cordura bag cut open (dura mater), with green sponge/mop (arachnoid mater), Saran wrap (pia mater) covering a model brain.

• 2. Place water in Cordura layer with sponge to simulate CSF and float brain-pia mater on sponge (Fig. 2a).

• 3. Use a document camera projection to illustrate that the brain “floats” in these tissue layers.

Part B: “Egg in Jar Floats” (~2 minutes) - Reinforcing an intuitive understanding of the mechanics of a lumbar puncture (“spinal tap”) in a closed CSF-system

• 1. This option includes placing a red dyed hard-boiled egg in a small transparent glass jar with lid, which is filled with salt-water (Fig. 2b). The idea is simply to extend the concept that the brain (egg) when placed into a buoyant fluid (“CSF” in jar) will float regardless of orientation of the jar.

• 2. The colored egg (typically red pickled eggs from gas station) are highly visible even when viewed from the back of the room.

• 3. Turn your head 90 degrees as if simulating sleeping, and turn the jar 90 degrees to the side, and note that the egg/brain still floats.

• 4. Ask class, “Describe what might happen if you did a handstand, turning the jar 180 degrees upside down. What will happen to the egg/brain+spinal cord?”

Part C: “Solid sphere floating on water fountain” (~2 minutes) - Demonstration of how the brain may sink into the foramen magnum during a lumbar puncture.

• 1. Prior to demonstration, fill the fountain with water (Fig. 2c), place under the document-camera system, and test that the power strip at the lectern can turn the fountain off and on readily.

• 2. One may presage the Part 2C demonstration by introducing the concept of a lumbar puncture (“spinal tap”), why a patient might need one, and/or contraindications.

• 3. Extending the concept from Part A, at lecture hall tap the solid sphere on tabletop to demonstrate that it’s solid. Turn on document camera.

• 4. Ask the class, “Predict what will happen when you place the solid sphere onto the waterspout?” (“pressurized CSF” system).

• 5. The sphere floats and begins to rotate, which is easily viewed.

• 6. Next ask the class, “Predict what happens when too much CSF is removed too quickly during a lumbar puncture.” To simulate this, turn off the pump and the sphere dramatically stops rotating/floating and sinks into the spout (foramen magnum). This leads to an instant headache.

• 7. Have your patient lie on their side to relieve the pressure, allowing the brain to float in the lateral surface of the skull/calvarium. Inform them that a patient should then wait 15 minutes or so until the CSF fluid has sufficiently reconstituted. Reiterate that CSF production is continuous, as it oozes out of the choroid plexus and ependymal cells lining the ventricles.

• 8. One can state factoids about how much CSF is produced daily, how much is in the head at any one time. Invite students to discuss the demonstration with the follow up questions to assess learner understanding of material:

  • a. What pathologies related to hydrocephalous conditions can be introduced?

  • b. Indicate how and why a space occupying lesion (e.g. hemorrhagic stroke) might present as a life-threatening condition through mass effect.

  • c. Describe CSF composition and how to read clinical tables that are typically provided on NBME National Board exams.

Part D: “Shake egg in bottle” which does not break (~2 minutes). Demonstration of how a closed-CSF system protects the brain and cord from concussion/damage during violent impacts. This standalone demonstration works well after Parts A-C above.

• 1. Begin by having the students recap the “egg in jar floats” demonstration from Part B.

• 2. Next state that you have a raw egg and place the egg in a topped off jar of water (Fig. 2d).

• 3. Quickly place the lid on to avoid air pockets. Wipe dry. Select a couple of students, ideally shyer ones near back of room to garner learner-centered attention, to try to violently shake the jar to “crack the egg” inside (without impacting the jar onto a surface). Humor will naturally develop with this approach: Run with it, as this is what will instill longer-term retention of the related didactic concepts.

• 4. One can play upon American football scenarios and/or the movie “Concussion”, which uses a similar scenario to illustrate the concept of chronic traumatic encephalopathy (CTE).

• 5. Return to front of the room. Assuming no one could crack it, remove egg from bottle and crack it open (or fully open) into a pan to demonstrate that the egg was indeed raw (for dramatic effect).

• 6. Extending components of the demonstrations throughout a lecture can be more effective than showing this all at once. This leads to anticipation about what is coming up later in the lecture, and you can teach other content between demonstrations. Be certain the ‘plumbing’ is operational prior to lecturing, as having to fix an apparatus during lecture does not come across well. Have a “caution wet floor” placard and few towels on hand in case of spillage, and to facilitate possible clean up.

STUDENT ASSESSMENT/REFLECTION

Students can be assessed through their in-class discussions and participation.

Appendix 3

Survey Asking Respondents About In-Class Educational Teaching Demos. The below image shows question #14 (of a full survey with 17 questions) to which both the M1 and M4 student cohorts responded. This question included ten “live” demonstrations to be rated, and numbers 5 (Demo #2), 6 (Demo #1), and 10 (Demo #3) were those addressed in the present study.