The lesion game: a special communication.

The Lesion Game [TM]: A Special Communication

The Lesion Game [TM] is a personal computer program that allows the user to view and study muscle innervations and nerve lesions of the brachial plexus. The core of the program is a table that consists of 44 brachial plexus lesions, 50 muscles, and 2 sensations (for brachium and forearm) of the upper extremity, which are innervated by the brachial plexus. After the program randomly selects a lesion, the user attempts to find the lesion in as few guesses (manual muscle tests) as possible. As muscles are selected (muscle tested), the computer searches the table to find the appropriate "strength" of weak or normal, based on the location of the randomly selected lesion. After displaying the strength of the muscle selected, a graphic representation of the strength is shown on a diagram of the brachial plexus. The graphic aspect of the program helps the user to visualize areas of the brachial plexus that may still contain the lesion. While playing the Lesion Game [TM], the user can view a detailed picture of the brachial plexus, view all the possible lesions of the Lesion Game [TM], or view charts of upper extremity innervations. An additional program mode allows beginning users to view and study muscle innervations without having to solve lesions. The program is extremely simple to use because it is entirely mouse-driven. [Guiteras DJ: The Lesion Game [TM]: A special communication. Phys Ther 69:858-862, 1989]

Key Words: Brachial plexus; Computers; Education: physical therapist, teaching methods; Upper extremity, general.

A thorough understanding of the human muscular system continues to be an important aspect of physical therapy, both in study and in clinical practice. A component in acquiring such a level of understanding would likely include tables and charts that describe and define muscle attachments, action, and innervation. Knowledge of these basic muscle attributes provides a foundation for assessing a muscle's level of function versus dysfunction. The difficulty in acquiring such knowledge lies not in the ability to locate adequate references; it is in attempting to retain such information that difficulties arise. I have created a personal computer-based application to assist in learning and reviewing at least part of the basic muscle attributes. The Lesion Game [TM] computer program is a learning tool that is designed to serve as an adjunct to physical therapy curricula by facilitating the learning and understanding of muscle innervations and lesions in relation to the brachial plexus.

The concept for the computer program was derived from an exercise that is part of the physical therapy curriculum at California State University, Northridge (Calif). The exercise, which is called "the lesion game," provides a way for students to test their knowledge of upper extremity muscle innervations. The game consists of the professor selecting a hypothetical brachial plexus lesion and then having the students attempt to locate the lesion in as few educated guesses as possible. The "guesses" consist of asking the professor the strength of various upper extremity muscles. The professor reports the strength of the muscles in question as either "weak" or "normal," based on the location of the lesion he or she has selected. The Lesion Game [TM] computer program serves as the professor in creating a simulation of the lesion game exercise. This simulation allows students to study upper extremity innervations in an unhurried manner and at a pace that coincides with their level of expertise.

Game Concept and Program Design

The lesion game is based on the concept of differential diagnosis of brachial plexus lesions through muscle testing. The theory behind this concept is that a clinician could identify a single lesion location or could generalize about multiple lesion locations through standardized muscle testing procedures. The purpose of the Lesion Game [TM] is to simulate this procedure for the purposes of studying muscle innervations, analyzing nerve pathways throughout the brachial plexus, and studying the functional deficits that would result from one lesion versus another. It should be noted that the Lesion Game [TM] is not intended in any way to be a substitute for, or an adjunct to, a clinical patient evaluation. The program functions merely as a test of one's understanding of upper extremity muscle innervations in relation to the brachial plexus. The computer serves as the patient (or the professor), offering strengths and weaknesses that are consistent with various brachial plexus lesions. Case studies of actual brachial plexus lesions identified by the differential diagnosis procedure are given by Kendall and McCreary.[1] The current version of the Lesion Game [TM] offers only single-site lesions.

In an effort to supply the computer with information necessary to assume the role of the patient, a table was constructed. The first dimension of the table consists of 44 single-site lesions that were created by examining a brachial plexus diagram and determining which areas of the brachial plexus could actually be "tested out," that is, lesion sites that could be exactly identified through muscle testing. Analyzing the brachial plexus this way revealed that not all seemingly possible lesion sites (ie, before and after every branch or crossing of a pathway) could be located with a specific muscle test. This finding means that in the clinical setting with a real patient--and a real lesion--the actual lesion location may not be exactly identifiable through muscle testing. Several of these types of lesions have been included in the Lesion Game [TM] program to further illustrate this point.

The second dimension of the table consists of the 50 muscles innervated by the brachial plexus (C5-T1), in addition to sensation for the medial aspect of the brachium and the forearm. For each of the 44 possible lesions, a "strength" of either weak or normal (impaired or normal for sensation) was assigned. This assignment of strengths was performed methodically by deciding what each muscle's strength would have to be, knowing the muscle innervations and the location of each lesion (44 possible lesions x [50 muscles + 2 sensations] = 2,288 entries). It is assumed that all weaknesses have developed as a result of a severed nerve along an innervation pathway.

At the start of the game, the program uses a random-number generator to choose a lesion numbered from 1 to 44. A graphic representation of the possible lesions found in the Lesion Game [TM] can be requested while playing the game (Fig. 1). When the user begins to "test" muscles by choosing a particular muscle from a menu, the computer cross-checks the randomly selected lesion with the muscle selected. The program then reads the table to find the appropriate strength of that muscle for the lesion in question.

In addition to displaying the strength of the muscle selected, a graphic representation of the muscle's strength is shown on the diagram of the brachial plexus. This graphic representation of the muscle's strength is performed by "filling in" the brachial plexus diagram in black along the nerve impulse pathway of a muscle. Areas of the brachial plexus that are not shaded in black represent possible lesion areas. The blackening of the brachial plexus occurs in two cases. The first case is in the normal-strength muscle in which the brachial plexus is blackened throughout the muscle's innervation. The brachial plexus is blackened to indicate that a lesion cannot be located along the nerve pathway of a normal-strength muscle. (If the lesion were located along the muscle's nerve pathway, then the muscle would be weak.)

The second case in which a portion of the brachial plexus is blackened is when a muscle is reported as weak for a particular lesion. If a muscle is weak, the lesion must be located somewhere within that muscle's innervation. The graph for a weak muscle thus is shown by blackening all areas of the brachial plexus except throughout the muscle's innervation. An example of the graphing procedure can easily be illustrated by using the biceps brachii muscle. If the biceps brachii muscle strength were normal, the computer would blacken the brachial plexus diagram from C5-6 through the musculocutaneous nerve. If the biceps brachii muscle strength were weak, the computer would blacken the brachial plexus everywhere except C5-6 through the musculocutaneous nerve.

The object of the game, therefore, is to select muscles until a single section of the brachial plexus is left unshaded. When playing the Lesion Game [TM], certain muscles offer many clues to the location of the lesion, whereas other muscles offer few or no clues (Fig. 2). "Successive graphing," a process whereby new graphs are superimposed on existing graphs, is the key to the Lesion Game [TM]. As new graphs are superimposed on the brachial plexus diagram, the possible areas for lesions decrease. The challenge of the game is to find the lesion in a few muscle tests as possible.

When the user believes that he or she has located the lesion, the proposed lesion location can be checked by the computer. Proposed lesion sites are indicated to the computer by the user via the "mouse." The user moves the mouse until the pointer on the screen is near the lesion location. The computer checks to determine whether the lesion selected by the user matches the lesion randomly chosen at the start of the game. When the user indicates the correct lesion, the computer shows the correct lesion location on the diagram of the brachial plexus. If the user proposes an incorrect lesion, the computer again shows the correct lesion on the brachial plexus diagram, but also simultaneously shows the incorrect lesion location, allowing an easy comparison of the two lesion sites.

Lesion Game [TM] Variations and Options

In addition to the basic Lesion Game [TM] concept as described above, variations of the game exist to increase or decrease the level of difficulty. The game variations allow the program to be challenging to first-year physical therapy students as well as to experienced clinicians. The most basic variation allows the user to view a diagram of a brachial plexus with labels for all components, such as roots, branches, divisions, and the names of specific nerves. This feature is most useful for the user who knows the nerve root numbers for a muscle but cannot remember the location of the muscle's nerve on the brachial plexus diagram.

Another game option allows access to the program's nerve and spinal cord root charts, which contain the nerves and spinal cord levels for upper extremity muscles. The purpose of including these charts in the program is to discourage the user from guessing muscles to be tested. When a difficult lesion is presented, the user can check the charts to find the next best muscle to be tested. The muscle innervation information contained in the nerve and spinal cord root charts and the Lesion Game [TM] data table is adapted from Kendall and McCreary.[1] The nerve and spinal cord root levels for a muscle shown in boldfaced type in the table represent Kendall and McCreary's compilation of the most common nerve supplies identified in cadaver dissection by various anatomists.[1] Reported muscle grades from the Lesion Game [TM] are based on these compiled spinal cord root levels.

An important game option is the "graph-delay" feature. Graph delay works by controlling when the graph of a muscle's strength is shown. When a muscle has been selected by the user and its strength has been reported, the computer can either graph the muscle's strength immediately or it can delay graphing. The user's level of knowledge of muscle innervations can be tested in this way because this feature allows the user to imagine how the brachial plexus diagram will look when the muscle is graphed, that is, where the computer will fill in the brachial plexus diagram based on the strength of the muscle that was chosen. This procedure of "thinking ahead" can be expanded to include deciding how the graph will look if the muscle is weak versus if the muscle were normal.

A final game option serves as a scorekeeper, indicating the ratio of correct versus incorrect lesion locations selected by the user. This option also indicates the number of muscle tests that were made to find a particular lesion.

Studying Muscle Innervations Without Use of Lesions

In addition to the lesion-game approach to studying muscle innervations, the Lesion Game [TM] program offers another mode that simplifies the study of muscle innervations while still using the graphic aspect of the program. Selecting muscles while in this mode allows the computer to display a graphic representation of a muscle's innervation without the concern for lesions. The user can select any muscle from the five joint menus in the same manner as in the Lesion Game [TM]. The program will then display the graph superimposed on a diagram of the brachial plexus. When a new muscle is selected, the previous graph is cleared and the new graph is shown. The user can choose the type of diagram the graphs will be superimposed on: a general overview of the brachial plexus or one that shows its various components. The user also has access to most of the options available in the Lesion Game [TM] including the nerve and spinal cord root charts, a detailed diagram of brachial plexus labels, and the ability to view the possible lesions in the Lesion Game [TM].

When a user is confident of his or her knowledge of upper extremity muscle innervations, the lesion mode of the Lesion Game [TM] program can be entered. It is possible to switch from one mode of the program to the other while using either mode. It is recommended that users switch between modes frequently so that newly learned innervations can be applied and areas that need more work can be identified.

Computer Program

The Lesion Game [TM] program was written in Microsoft BASIC for the Macintosh [TM] personal computer.(*) Several criteria were established for the design of this program, which dictated not only the program environment but the type of computer to be used. The most important focuses of these criteria were ease of use, short program learning time, and the ability of the computer to display detailed graphics.

Because the Macintosh [TM] operating system is primarily mouse-driven, it was possible to write the Lesion Game [TM] program in such a way that the user is never asked to respond via the keyboard. The benefits of this feature can be illustrated by imagining how a user might go about selecting a particular muscle from a list of muscles contained in a computer program. Using a computer with a keyboard-driven operating system (IBM([single dagger]) and IBM-compatible computers), the user might type the name of the muscle desired or an abbreviation of a muscle name or use a function key that corresponds to a muscle abbreviation on the computer screen. These methods are commonly used in microcomputer applications; however, they often require more interpretation by the user. Keyboard-driven programs can also be frustrating to use, as seen when a muscle name is entered by the user and then rejected by the program. The reason for the rejection could be that the name of the muscle was misspelled or was in some way different from the form of the word recognized by the program. In either case, it is then the user's job to decide what went wrong.

Because the Lesion Game [TM] was programmed for the Macintosh [TM] operating system, a much different approach could be taken to allow the easiest interaction between the user and the computer. The Macintosh [TM] operating system incorporates a pointing device called a mouse to choose from available options at any point in a program. In the case of the Lesion Game [TM] program, the user can select a muscle from any of the five joint menus: Shoulder Girdle, Shoulder, Elbow, Wrist, and Hand. Each joint menu contains a list of muscles related to that menu name. To choose "biceps," for example, the user would simply look under the Elbow menu. By having the muscle names arranged by joint menus, the user can easily and quickly access the muscle desired. The user never has to type the name of the muscle to select a muscle.

To create the look of filling in areas of the brachial plexus diagram when showing muscle strengths, the computer reads graphic files that were created using a "paint" application and then stored on the Lesion Game [TM] diskette. These graphic files "fit" over the brachial plexus diagram, which serves as a template. Graphic files for muscle strengths were used instead of having the computer calculate where the brachial plexus diagram should be filled in, both to simplify programming and to greatly increase the rate at which the graphics are shown on the screen. Muscle graphs are shown nearly instantaneously after being selected by the user. Graphic files, unlike program codes that calculate graphic images, cannot be published; that is, the information that comprises the graphic file cannot simply be converted into print and then typed into the computer by the user. The Lesion Game [TM] program, therefore, can be distributed only on diskette.

The Lesion Game [TM] program, when coupled with a Macintosh [TM] personal computer, becomes an effective tool for presenting muscle innervations in an interesting format. In addition to providing a platform for muscle innervation study, the Lesion Game [TM] allows further appreciation of this information by presenting its relevance to the brachial plexus. I hope that the Lesion Game [TM] program will stimulate physical therapy educators to acknowledge the incredible potential the personal computer has for supplementing physical therapy curricula. [Figures 1 to 2 Omitted]

(*)Apple Computer, Inc, 20525 Mariani Ave, Cupertino, CA 95014. ([single dagger])International Business Machines Corp, 1000 NW 51st St, Boca Raton, Fl 33432

Reference

[1]Kendall FP, McCreary EK: Muscles: Testing and Function, ed 3. Baltimore, MD, Williams & Wilkins, 1983, pp 35, 38-52

D Guiteras, BS, PT, is a physical therapist, 5307 Sepulveda Blvd, #301, Van Nuys, CA 91411 (USA).