Neuromuscular Examination PDF

© Robert Kneschke/ShutterStock, Inc. CHAPTER 10 Neuromuscular Examination C HA P TER OU TLINE Introduction Coordination Upper Motor Neuron Clonus Te...

© Robert Kneschke/ShutterStock, Inc. CHAPTER 10 Neuromuscular Examination C HA P TER OU TLINE Introduction Coordination Upper Motor Neuron Clonus Testing Tests Pronator Drift Test Somatosensory INTRODUCTION Pathological Superficial Function FUNDAMENTAL CONCEPTS INTRODUCTION Reflexes INTRODUCTION PROCEDURE FUNDAMENTAL CONCEPTS Upper Extremity Tests Muscle Tone Chapter Summary FUNDAMENTAL CONCEPTS Lower Extremity Tests PROCEDURE PROCEDURE Testing for Spasticity Light Touch Balance Deep Tendon Reflexes Protective Sensation INTRODUCTION Pain (Sharp/Dull Test) FUNDAMENTAL CONCEPTS Vibration Sensory System Temperature Sensorimotor Integration CO M PA N I O N V I D E OS Position Sense Motor Output Discriminative Sensation The Role of Cognition The following videos are available to accompany Spinal Nerve Root PROCEDURE this chapter: Integrity Confidence in Balance Gaits Deep Tendon INTRODUCTION Sitting Balance Light Touch Reflexes (Normal FUNDAMENTAL CONCEPTS Static Standing Balance Tests and Abnormal) Dermatomes Protective Sensation Myotomes Reactive Balance Tests Balance (Normal and Anticipatory Balance Pain (Sharp/Dull Test) Abnormal) PROCEDURE Tests Vibration Dermatomes Dynamic Balance Tests Cranial Nerve Myotomes Temperature Assessment Deep Tendon Reflexes Cranial Nerve Assessment Position Sense Testing for Spasticity INTRODUCTION (Proprioception) Deep Tendon INTRODUCTION FUNDAMENTAL CONCEPTS Discriminative Reflexes (Normal FUNDAMENTAL CONCEPTS Hypotonic DTRs Sensation and Abnormal) Hypertonic DTRs PROCEDURE PROCEDURE Dermatomes and Clonus Testing Myotomes  Fundamental Concepts 351 Section 1: Somatosensory Function INTRODUCTION Thalamus The sensory system is responsible for receiving and inter- Somatic preting information from the surrounding environment. sensory cortex This includes what we see (visual), hear (auditory), taste (gustatory), smell (olfactory), and feel (somatosensory), and how we maintain our body in space (vestibular). Cranial nerves play a large part in our ability to see, hear, taste, smell, and orient our body in space; these will be covered in a later section of this chapter. The present section will consider the somatosensory system, which allows us to feel or sense things on or within our body. Somatosensory function includes perception of light touch, temperature, pain, vibration, joint position, and discriminative sensation.1 Conditions or injuries that affect the central or peripheral nervous system can reduce Midbrain or eliminate an individual’s ability to sense any or all of the functions listed in the previous paragraph. At first thought, loss of somatosensory function may not seem as concerning as losses in other areas, such as strength, cognitive process- ing, or peripheral circulation. However, consider the case of a woman with type 2 diabetes who, because of an inability to sense a shard of glass inside her shoe (loss of light touch, Medulla pressure, and pain), developed a large wound on her foot that became infected and, after months of failed attempts Dorsal to heal the wound, resulted in an amputation at the ankle. root This is only one of many examples of how somatosensory ganglion Fine touch, vibration, function is vital to our own protection and self-care. cells and position sense afferent fiber FUNDAMENTAL CONCEPTS FIGURE 10-1 demonstrates a rudimentary mapping of the Spinal cord conscious sensory pathways in the human nervous system. Pain and Peripheral In simplistic terms, when peripheral receptors (e.g., within temperature sensory skin, ligaments, muscles, or joint capsules) are stimulated, afferent fiber receptors information is transmitted along afferent nerves to the spinal FIGURE 10-1 Simplistic representation of somatosensory cord. Within the spinal cord, these messages ascend to the pathways from peripheral receptor to the somatosensory brain in either the posterior column (light/fine touch, vibra- cortex. tion, and position sense) or the spinothalamic tract (crude/ coarse touch, pain, and temperature). Nerve fibers in the spi- nothalamic tract cross to the contralateral side within one or compressed—typically because of a narrowing of the ver- two spinal cord levels of entry while fibers from the posterior tebral foramen, facet hypertrophy, or pressure from a her- columns cross at the level of the medulla. The nerve fibers niated intervertebral disc—sensory changes occur along continue to ascend to the thalamus, where they synapse and the dermatome. Thus, patients who present with signs and project information to the somatosensory cortex of the brain symptoms that include sensation changes in a dermatomal (parietal lobe) where the information is processed.1 pattern, weakness of the muscles innervated by that nerve Through various forms of testing, identification of pat- root (myotome), and a diminished deep tendon reflex are terns of sensory loss can shed light on the type or extent of most likely experiencing nerve root compression. The next an injury or disease process. Damage anywhere along the section of this chapter describes dermatomes and myotomes sensory pathway, from the sensory receptors in the periph- in detail. ery to the somatosensory cortex of the brain, can diminish, Dysfunction elsewhere along the nerve pathway will alter, or eradicate one’s ability to receive and interpret this present in non-dermatomal patterns. If damage has occurred vital information.2 If compression or damage occurs spe- at a specific peripheral nerve (such as the radial nerve in cifically at the nerve root, sensation will be diminished in the arm or the saphenous nerve in the leg), the sensation a dermatomal pattern.3 Dermatomes are strips of skin that loss will be unilateral and isolated to the corresponding area correspond to a particular nerve root. When a nerve root is shown in FIGURE 10-2. This may be caused by local nerve 352 CHAPTER 10 Neuromuscular Examination Cervical plexus Cervical plexus (supraclavicular nerves) Lateral brachial cutaneous Medial brachial cutaneous Medial Brachial Intercostobrachial Lateral cutaneous Lateral Antebrachial Medial Antebrachial cutaneous Medial Lateral cutaneous Iliohypogastric Radial Radial Median Ulnar Ulnar Median Lateral femoral cutaneous Ilioinguinal Obturator Genitofemoral Posterior femoral cutaneous Lateral femoral cutaneous Femoral Obturator Femoral Common peroneal Common peroneal Saphenous Saphenous Tibial Superficial peroneal FIGURE 10-2 Sensory distribution of peripheral nerves. Data from Swartz M. The science of the physical examination. In: Swartz M. Textbook of Physical Diagnosis. 6th ed. Philadelphia, PA: Saunders Elsevier, 2010. compression, crush injury, or a surgical incision. Symptoms of tight boots. This can result in numbness and tingling are localized, and the extent of functional difficulties may on the dorsum of the foot (as well as foot drop due to be relatively small. If damage has occurred within the spi- weakened or absent dorsiflexion).4 nal cord or in the brain, somatosensory loss will often be Spinal cord injury. Typically causes damage to several much more extensive and function will likely be impaired or all ascending and descending nerve tracts. Can result to a greater degree. Several examples of conditions specific in varied somatosensory and motor dysfunction to the peripheral or central nerve pathways are described (minor to complete loss) below the level of the lesion.1 in the following list. Tumor. In the spinal cord or brain, if located within tract(s) of the spinal cord that carry somatosensory Carpal tunnel syndrome. A condition localized to the information, the thalamus, or cortex, may have a vari- median nerve distribution (thumb and first 2–3 fin- able effect on somatosensory (and motor) function.1 gers) caused by compression of the nerve. This can Lesions in the brain. Whether from a stroke, traumatic result in numbness, tingling, pain, weakness, and brain injury, or tumor, lesions may negatively affect atrophy.4 somatosensory (and motor) function if the thalamus Common peroneal (or fibular) nerve palsy. A condition or parietal lobe is compromised.1 Will typically present caused either by a blow or laceration to the lateral knee with unilateral somatosensory deficits on the side in the area of the fibular head or from prolonged com- opposite the lesion, unless both hemispheres of the pression, such as during cross-legged sitting or wearing brain are involved.  Fundamental Concepts 353 early symptoms of multiple sclerosis and should there- fore be assessed when any suspicion of this condition is present.8 Guillain-Barré syndrome. A nonprogressive autoim- mune disease that causes demyelination of the axons in the peripheral nervous system. This demyelination may slow or block neural conduction along both motor and sensory pathways.9 Hansen’s disease. A chronic bacterial infection, also known as leprosy (although rare, this still occurs in the United States10), that primarily affects the skin and peripheral nerves. In 90% of cases, the first symptom noted is numbness in the distal extremities.11 Lyme disease. An inflammatory disease caused by a bite from an infected deer tick. Lyme disease often goes undiagnosed as its presentation can be variable and may mimic a number of other conditions. Along with various additional signs and symptoms, loss of sensa- tion in the arms and legs is common and can develop rapidly after the individual is infected.12 Alcoholic neuropathy. Can lead to diminished somato- sensory function as well as motor impairments, although sensory loss is first to appear.13 The mecha- nism of loss appears to be axonal degradation and tends to present in the stocking and glove distribution.14,15 Approximately 1 of every 12 persons (8%) in the United States abuses alcohol or is alcohol dependent,16 and a large number of those develop neuropathy. Because many people deny problems with alcohol, differential FIGURE 10-3 The “stocking and glove” distribution of somatosensory loss. diagnosis can be challenging. Reproduced from the Agency for Toxic Substances & Disease Registry. “Arsenic Toxicity: What are the Physiologic Effects of Arsenic Exposure?” Centers for Disease Control and The ability to recognize various sensations is important Prevention. Available at: www.atsdr.cdc.gov/csem/csem.asp?csem=1&po=11. Accessed for injury prevention as well as safety. Unfortunately, somato- March 15, 2016. sensory loss occurs so gradually in a number of conditions that individuals do not even register the loss until an injury has A number of disease processes cause nonselective nerve occurred. Diminished ability to sense pain and pressure can damage; in these cases, somatosensory loss will typically allow a harmful stimulus to damage cutaneous or subcutane- occur bilaterally and symmetrically. It also will not follow ous tissues. Loss of this sensation on the bottom of the feet is any known nerve pathway. Several conditions primarily particularly dangerous because of the number of potentially reduce or block sensory nerve conduction from the distal harmful items people tend to step on. One patient presented extremities (the feet, lower legs, and hands), which is called to a physician’s office to determine the source of a painless but a “stocking and glove distribution”5 (see FIGURE 10-3). The enlarging reddened area that had been present for 2 months. functional impact of these conditions with regard to somato- A radiograph determined that the source was a carpenter’s sensory loss may range from minor to extensive. Several of nail embedded in the patient’s foot, which the patient did not these conditions are described in the following list. sense. Because of osteomyelitis that had developed over the Diabetes mellitus. A metabolic disease in which the 2-month period, the foot required amputation.17 Unfortu- body fails to produce or adequately use insulin. This nately, similar clinical stories are not uncommon. frequently results in progressive nerve damage that Individuals who lack normal somatosensory input affects sensation in the feet, legs, or hands (often in the also are at greater risk for falls.18–21 Imagine how difficult stocking and glove pattern).6 Changes in sensation are it might be to walk on a grassy slope without the ability to often one of the first notable symptoms of type 2 dia- sense unevenness in the ground through the pressure recep- betes, which is why sensation testing is vital for early tors in your feet, the position of your foot and ankle joints detection. at various angles of the ground, or the fact that your feet are Multiple sclerosis. A progressive autoimmune disease touching the ground at all. As will be discussed in a later that causes demyelination of the axons in the central section of this chapter, the body relies primarily on three nervous system. This demyelination slows or blocks sensory systems to maintain balance: visual, vestibular, and neural conduction along both motor and sensory path- somatosensory. With a compromise in any of those systems, ways.7 Sensation changes (numbness and tingling) are fall risk increases.22 354 CHAPTER 10 Neuromuscular Examination PROCEDURE Common methods of testing different aspects of the somatosensory system will be described. Many of the tests presented are easy to do, require little or no equipment, and can be completed in less than 1 minute. Therefore, if there is any suspicion of a disease process, injury, or condition known to cause somatosensory dysfunction, there is little reason why these tests should not be carried out. The following procedural concepts should be consid- ered with each test outlined: Many of these tests are conducted with the patient’s eyes closed, so it is very important that you first inform the patient about the purpose of each test, what you plan to do, and how he or she should respond to each stimulus. Testing should not occur over clothing. Testing should compare the right to the left side (even if both sides are affected). Testing should compare distal to proximal areas. Areas of calloused skin should be avoided, if possible, FIGURE 10-4 Assessment of light touch using a cotton ball. as these areas generally have poor sensation.15 The patterns and pace of your testing should be varied b. If both extremities are affected, you should com- so patients cannot recognize a pattern and respond cor- plete testing on one limb before you move to the rectly with an educated guess. other limb. If somatosensory loss is present, attempt to map the i. Begin distally (at the toes or tips of the fingers) area with distinct boundaries to best determine the and work proximally until the patient feels nor- type, extent, and severity of the lesion or condition. mal light touch. Documentation of your findings should be complete and descriptive with regard to type of test, specific Performing the test: areas tested, area of dysfunction identified, and side- 1. Ask the patient to close his or her eyes. to-side differences. 2. Ask the patient to tell you when touch is felt. 3. Gently touch the patient’s skin, being careful not to Light Touch “dent” the skin (which stimulates mechanoreceptors) Spinal tract: Posterior columns (spinothalamic tract car- (see FIGURE 10-4). ries crude/coarse touch) a. Avoid the temptation to stabilize the tested limb Equipment required: cotton, gauze, or none (Although the with your other hand as the patient may register use of cotton or gauze is less likely to invoke mechanore- the stabilizing touch, and not the testing touch. ceptors, which should not be stimulated in light touch test- b. If the patient does not register your touch, you may ing, many clinicians prefer to use the pads of the first or test the area again, but do not increase your touch second fingers as the testing stimulus.) pressure. If touch is not registered after the second Preparation: attempt, simply record the area as “insensitive.” 1. Instruct the patient regarding what you will be doing c. The touch should not be performed with a stroking and what verbal responses you would like the patient or sweeping motion. to give. d. The patient may feel a normal touch, a diminished a. You may perform a trial test on an area not being sensation of touch (comparing side to side or prox- formally assessed to ensure that the patient under- imal to distal), or no touch at all. stands your instructions. 4. Continue the procedure at random intervals until the 2. Determine the areas of skin you will be assessing, and boundaries of normal and abnormal sensation have position the patient appropriately so you have full been located. access to the appropriate areas of skin. a. If you suspect a unilateral peripheral nerve dys- Protective Sensation function, testing specific areas on the affected and Spinal tract: Spinothalamic and posterior columns unaffected sides simultaneously is appropriate to Background information: Assessment of protective sensation allow the patient to directly compare normal sen- is a specialized form of light touch testing. Protective sensa- sation to abnormal sensation (refer to Figure 10-2). tion is the minimum level of light touch recognition required i. Test enough areas to allow you to “map” the of the somatosensory system to warn the individual of im- boundaries of “normal” and “abnormal” light pending danger (such as a diabetic foot that cannot sense a touch sensation. pebble in the shoe). Formal assessment requires the use of  Procedure 355 FIGURE 10-5 A full set of Semmes-Weinstein FIGURE 10-6 Suggested areas to test for protective monofilaments (left) and a 5.07 (10 gm) disposable 5.07 sensation on the foot. monofilament (right). Adapted from the U.S. Department of Health and Human Services. LEAP project. Available at: www.hrsa.gov/hansensdisease/pdfs/leaplevel3.pdf. items called monofilaments (see FIGURE 10-5), which are 3. With the monofilament at a 90° angle to the patient’s reliable and valid tools for identifying individuals at risk for skin, touch the area with the end of the filament until developing foot ulcers.23,24 Monofilaments in an extensive set it bends slightly. Maintain the pressure in the bent posi- may be numbered from 1.65 to 6.65. These numbers corre- tion for 1.5 seconds, then pull the monofilament away spond to a range of 0.008–300 gm of force required to bend from the skin (see FIGURE 10-7). the monofilament upon contact with a surface.25 Monofila- a. Do not place the monofilament in a wound or over ments with a small number require greater sensitivity to light a callus or scar. touch compared to the higher numbered monofilaments. b. If the patient does not register the touch of the While healthy individuals with normal sensation can typically monofilament, move on to the next area. detect the 3.61 (0.4 gm) monofilament on the plantar aspect c. Any areas not registered on the first attempt may be of the foot,26 studies have shown that persons must be able to tested again after the first sequence is complete. If sense the 5.07 (10 gm) monofilament to have protective plan- not registered on the second attempt, the patient’s tar sensation.27–29 Two meta-analyses of published research ability to sense the force of the specific monofila- indicate that monofilament testing is the best screening tool ment is likely absent. for identification of clinically significant lower extremity neu- 4. Perform on one foot at a time, but test both feet during ropathy.30,31 It also has been shown that at-risk individuals are the session. accurate in performing self-administered sensory testing at home using a low-cost 10-gm monofilament.32 Equipment required: the 5.07 (10 gm) monofilament is adequate for many clinical testing purposes; more extensive assessment can be accomplished with a set of monofilaments. Preparation (adapted from the Touch Test Sensory Evalu- ators Manual25): 1. Instruct the patient regarding what you will be doing and what verbal responses you would like the patient to give. a. You may perform a trial test on an area not being formally assessed to ensure that the patient under- stands your instructions. 2. Position the patient in supine or reclining with the lower extremities supported. The patient’s socks and shoes should be removed and the foot wiped clean with a damp cloth or alcohol swabs. a. There are nine specified areas on the plantar aspect of foot that should be assessed (see FIGURE 10-6).33 Performing the test: 1. Ask the patient to close his or her eyes. 2. Ask the patient to indicate “yes” or “now” each time the FIGURE 10-7 Technique for monofilament testing over monofilament is felt. first MTP joint on plantar surface of the foot. 356 CHAPTER 10 Neuromuscular Examination Pain (Sharp/Dull Test) Performing the test: Spinal tract: Spinothalamic 1. Ask the patient to close his or her eyes. Equipment required: options include the following (see 2. Ask the patient to tell you when he or she feels a stimu- FIGURE 10-8): lus by saying “sharp” or “dull.” 1. A clean, unused safety pin 3. Touch the patient’s skin with either the sharp or the dull 2. A sterile cotton-tipped applicator (wooden end broken stimulus; the pressure should be enough to slightly to create sharp stimulus) indent the skin, but the skin should never be broken 3. The screw-in pointed tip of a Buck reflex hammer (see FIGURE 10-9). 4. A paper clip with one end unbent to allow for one sharp a. If the patient does not register the stimulus, you and one dull end may test the area again, but do not increase the Preparation: stimulus pressure. If the sensation is not registered after the second attempt, simply record the area as 1. Instruct the patient regarding what you will be doing “insensitive.” and what verbal responses you would like the patient b. If the patient indicates “dull” when the stimulus is to give. sharp, do not increase the stimulus pressure; sim- a. You may perform a trial test on an area not being ply record the response as “incorrect.” formally assessed to ensure that the patient under- c. Abnormal responses include an inability to distin- stands your instructions. guish between the sharp and dull stimuli or not b. The patient should feel and understand the differ- feeling either stimulus. ence between the sharp (painful) stimulus and the dull (nonpainful) stimulus. 2. Determine the areas of skin you will be assessing, and position the patient appropriately so you have full access to the areas of skin to be tested. a. If you suspect a unilateral peripheral nerve dysfunc- tion, comparing similar areas on the affected and unaffected sides is encouraged (refer to Figure 10-2). i. Test enough areas on the affected side to allow you to “map” the boundaries of “normal” and “abnormal” pain sensation. b. If both extremities are affected, you should com- plete testing on one limb before you move to the other limb. i. Begin distally (at the toes or tips of the fingers) and work proximally until the patient is able to distinguish sharp from dull stimuli. (a) (b) FIGURE 10-9 (a) Technique for testing a patient’s ability to identify a sharp (painful) stimulus. (b) Technique for FIGURE 10-8 Example of items that can be used to testing a patient’s ability to identify a dull (nonpainful) examine pain (sharp/dull) sensation. stimulus.  Procedure 357 4. Continue the procedure at random intervals until the boundaries of “normal” and “abnormal” pain sensation have been located. a. Avoid a repeated pattern of sharp, dull, sharp, dull, etc. Vibration Spinal tract: Posterior columns Equipment required: a 128-Hz tuning fork (initiate vibra- tion by tapping it on the heel of your hand) Preparation: 1. Instruct the patient regarding what you will be doing and what verbal responses you would like the patient to give. a. You should demonstrate the vibratory sense on an unaffected bony prominence (sternal notch, chin, or mandibular angle) to ensure that the pa- tient understands the sensation as well as your instructions. FIGURE 10-10 Technique for vibration sense testing over the IP joint of the great toe. b. The patient should inform you if vibration is felt or not felt. i. If felt, the patient should inform you when the Temperature vibration sense is gone. Spinal tract: Spinothalamic (Note: This test is often omitted 2. Determine the areas you will be assessing, and position if pain sensation is intact.) the patient appropriately so you have full access to the Equipment required: options include the following: areas that will be tested. a. Distal areas are assessed first. 1. Two test tubes filled with hot and cold water i. If vibratory sense is normal distally, there is no a. The water in the hot test tube should not exceed need to test proximal areas. 113°F (45°C) to avoid burning the patient and to avoid stimulating the pain receptors.34 Performing the test: 2. Two tuning forks (one cooled by cold water and one warmed by hot water) 1. Ask the patient to close his or her eyes. 2. Ask the patient to tell you when a vibratory sense is felt. Preparation: a. Test the patient’s accuracy by performing several 1. Instruct the patient regarding what you will be doing tests when the tuning fork is not vibrating. and what verbal responses you would like the patient 3. Begin by placing the tip of the vibrating tuning fork to give. on the most distal bony prominence of the limb, a. You should demonstrate the cold and hot stimuli typically the distal interphalangeal joint of the index on an area of normal sensation so the patient has a finger or the interphalangeal joint of the great toe clear understanding of what should be felt. (see FIGURE 10-10). b. The patient should inform you if sensation is “cold” a. By lightly holding the toe or finger being tested, or “hot.” you can also feel the vibration. 2. Determine the areas of skin you will be assessing, and b. Abnormal responses include an inability to sense position the patient appropriately so you have full the vibration or indicating that the vibration has access to the areas that will be tested. stopped when it has not. a. If you suspect a unilateral peripheral nerve dysfunc- 4. If vibration sense is absent at the distal aspect of the tion, comparing similar areas on the affected and extremity, continue in a proximal direction until the unaffected sides is encouraged (refer to Figure 10-2). sense is felt. i. Test enough areas on the affected side to allow a. For the lower extremity, proceed to the first meta- you to “map” the boundaries of “normal” and tarsophalangeal (MTP) joint, medial malleolus, “abnormal” temperature sensation. tibial tuberosity, and anterior superior iliac spine b. If both extremities are affected, you should com- (ASIS). plete testing on one limb before you move to the b. For the upper extremity, proceed to the proximal other limb. interphalangeal joint, the metacarpophalangeal i. Begin distally (at the toes or fingers) and work (MCP) joint, the ulnar styloid process, the olecra- proximally until the patient is able to distin- non or lateral epicondyle, and the acromion process. guish cold from hot stimuli. 358 CHAPTER 10 Neuromuscular Examination Performing the test: Joint Position Test 1. Ask the patient to close his or her eyes. Preparation: 2. Ask the patient to tell you when he or she feels a stimu- 1. Instruct the patient regarding what you will be doing lus by indicating “cold” or “hot.” and what verbal responses you would like the patient 3. Place the tube gently against the patient’s skin (see to give you. FIGURE 10-11). a. With the patient’s eyes open, you should demon- a. Allow the stimulus to remain on the patient’s skin strate the two positions of “up” (which usually cor- for at least 2 seconds.34 responds to joint extension) and “down” (which b. Abnormal responses include an inability to dis- usually corresponds to joint flexion). This should criminate between cold and hot or inability to occur on an unaffected joint to ensure that the pa- sense the presence of the stimulus at all. tient understands the feel of the positions as well as 4. Continue the procedure at random intervals until the your instructions (see FIGURE 10-12). boundaries of “normal” and “abnormal” temperature i. Holding the sides of a distal phalanx between sensation have been located. your two fingers, move the joint up (stating “this a. Avoid a repeated pattern of cold, hot, cold, hot, etc. is up”) and down (stating “this is down”). ii. Do not hold the distal segment on the ventral Position Sense and dorsal aspects as this can provide pressure Spinal tract: Posterior columns stimulus upon movement, giving the patient Equipment required: none “hints” about the direction of motion. Background information: Our awareness of our own body iii. Do not allow your fingers to touch adjacent dig- position and movement in space is known as propriocep- its for the same reason. tion (from the Latin proprius, which means “one’s own,” b. On the joint just used for demonstration, you and perception). Proprioception is generally thought to should trial this test by having the patient close his differ from kinesthesia in that kinesthesia is more descrip- or her eyes and indicate “up” or “down” in response tive of one’s awareness that a joint (or body part) has to your motions. moved, whereas proprioception is more descriptive of the 2. Determine the joints you will be assessing, and position conscious and unconscious awareness of the static position the patient appropriately so you have full access to the of a joint. Input from receptors in skeletal muscle, tendons, areas that will be tested. and joints (including ligaments) provides constant infor- a. Distal areas are assessed first. mation about limb position and muscle action and also i. If position sense is normal distally, there is no assists in coordination of limb movements.1 Several tests need to test proximal areas. are thought to measure an individual’s conscious proprio- Performing the test: ception. Three of these tests—the joint position test, the joint space (mirroring) test, and the finger-to-nose test— 1. Ask the patient to close his or her eyes. are described below. The first test does not require any 2. Place your fingers on the lateral aspects of the distal motor activity or coordination from the patient and should digit to be tested. be performed first when known or suspected impairment a. In the lower extremity, begin with the interphalan- is present. geal joint of the great toe. FIGURE 10-11 Technique for temperature sense testing using FIGURE 10-12 Correct hand placement for performing the two test tubes filled with water (one cold and one hot). joint position test at the distal finger.  Procedure 359 b. In the upper extremity, begin with the interphalan- Finger-to-Nose Test geal joints of one finger. Preparation: 3. Move the selected joint slightly into the up or down position. 1. Instruct the patient regarding what you will be doing a. Extremes of motion are not required; individuals and the physical response required. with normal somatosensory function should be a. With the patient observing, demonstrate the test able to detect positional changes of a few degrees.34 on an assistant or colleague. b. Several trials should be performed at each joint and b. Ask the patient if he or she understands the test or in each direction. if further explanation or demonstration is required. c. The joint should be returned to the starting (neu- 2. The patient should be comfortably seated (performing tral) position between each trial. this test in supine is also possible). d. Avoid a repeated pattern of up, down, up, down, Performing the test: etc. 1. Ask the patient to close his or her eyes. 4. If joint movement sense is absent at the distal aspect of 2. Lightly touch one of the patient’s fingers, and ask the the extremity, continue in a proximal direction until the patient to touch his or her own nose with the finger that sense is felt. was touched. a. For the lower extremity, proceed to the MTP joint, a. Proceed with touching other fingers (on either hand) the ankle, and the knee. in a random fashion, and ask for the same response. b. For the upper extremity, proceed to the metacarpo- 3. Persons with proprioceptive deficits have difficulty phalangeal (MCP) joint, the wrist, and the elbow. doing this test accurately without visual input.3 4. Note: This test may be quite difficult (and thus not Joint Space (Contralateral Mirroring) Test5,35 valid) if patients have range of motion, strength, or Preparation: coordination deficits. 1. Instruct the patient regarding what you will be doing and the physical response required. Discriminative Sensation a. With the patient observing, demonstrate the test Spinal tract: posterior columns (plus portions of the cere- on an assistant or colleague. bral cortex) b. Ask the patient if he or she understands the test or Background information: Tests of discriminative sensation if further explanation or demonstration is required. require integration, analysis, and interpretation of touch, pres- 2. Determine the joints you will be assessing, and position sure, and position sense in the sensory cortex.1,5 Four of these the patient appropriately so you have full access to the tests—stereognosis, graphesthesia, two-point discrimination, areas that will be tested. and point localization—are described below. If there is severe a. Distal areas are assessed first. impairment of touch sensation or of position sense, a patient’s i. If joint space sense is normal distally, there is no performance on these tests will likely be poor. If a patient’s need to test proximal areas. touch sensation and position sense are good or only minimal- ly impaired, an abnormal finding on any of the following tests Performing the test: may indicate a lesion in the somatosensory cortex. 1. Ask the patient to close his or her eyes. Stereognosis (defined as “object identification 2. Move the finger or toe of the patient’s uninvolved extremity to a particular position. solely by touch”15) a. In the lower extremity, begin with the great toe or Equipment required: objects familiar to most people (paper the ankle. clip, coin, cotton ball, key, rubber band) b. In the upper extremity, begin with the index finger Performing the test: or the wrist. 1. Ask the patient to close his or her eyes and extend one 3. Ask the patient to mirror the position with the involved hand (begin with the unaffected side; if both sides are extremity. affected, begin with the dominant hand). a. Several trials should be performed using different 2. Place the object in the palm of the patient’s hand and testing positions. ask the patient to identify the object (see FIGURE 10-13). 4. If position sense is absent at the distal extremity, con- a. The patient may grip or manipulate the object, but tinue in a proximal direction until the patient can accu- only within the tested hand. rately mirror the position of the uninvolved 3. Perform several trials on both hands using different extremity. objects. 5. Persons with proprioceptive deficits have difficulty per- 4. Fine discrimination can be tested by asking the patient forming this test accurately without visual input. to identify the “heads” or “tails” side of a coin or to 6. Note: This test may not provide useful findings in the identify which coin is being held. presence of bilateral extremity involvement as the 5. The inability to identify common objects is called patient may not have a normal side to mirror. astereognosis. 360 CHAPTER 10 Neuromuscular Examination FIGURE 10-13 Test for stereognosis using a coin. FIGURE 10-15 Test for two-point discrimination using a discriminator tool. Graphesthesia (defined as “the ability to identify Two-Point Discrimination writing on the skin solely by touch”15) Equipment required: two paper clips (unbent to allow for Equipment required: the blunt end of a pen or similar object a pointed end) or a special two-point discriminator tool Performing the test: Performing the test: 1. Perform a demonstration with the patient’s eyes open 1. Ask the patient to close his or her eyes and extend one so he or she is oriented to the top and bottom of the hand (begin with the unaffected side; if both sides are “paper” (the patient’s skin) you will write on. affected, begin with the dominant hand). 2. Ask the patient to close his or her eyes and extend one 2. On the pad of one finger, touch the patient with two hand (begin with the unaffected side; if both sides are points simultaneously and ask the patient if one or two affected, begin with the dominant hand). points are felt (see FIGURE 10-15). 3. Draw a large number in the patient’s palm (see 3. Alternate touching with one and two points in a ran- FIGURE 10-14). dom fashion in several places on the fingers and hand. 4. Perform several trials on both hands, using different 4. Normally, individuals can discriminate two separate numbers. points that are 5 millimeters apart on the pads of the a. If the patient is inaccurate, try the test on the forearm. fingers.15 5. The inability to identify numbers drawn on the skin is 5. This may be performed on other areas of the body, but called agraphesthesia. normal distances vary substantially from one region to the next.15 Point Localization Equipment required: none Performing the test: 1. Ask the patient to close his or her eyes. 2. Lightly touch an area on the patient’s skin. 3. Ask the patient to open his or her eyes and then point to the place that you touched. 4. Repeat this on both sides and in various areas of the body. 5. Persons with intact light touch sensation and an intact somatosensory cortex can usually perform this with FIGURE 10-14 Test for graphesthesia with the clinician good accuracy. “drawing” a number on the patient’s palm.  Procedure 361 © Bocos Benedict/ShutterStock, Inc. PRIORITY OR POINTLESS? When somatosensory function is a PRIORITY If abnormalities are found, additional somatosensory to assess: tests should be performed. Patients who have known Assessment of somatosensory function should be per- or suspected dysfunction at the nerve root level may formed with any patient reporting symptoms consistent be screened with generalized sensory tests, but further with nervous system involvement. Sensory function assessment should also take place specific to dermatomal specific to both the posterior columns and spinotha- patterns. lamic tract should be assessed. This typically includes light touch (posterior columns) and pain (spinothalamic When somatosensory function is POINTLESS tract). If these tests are normal, you may proceed with to assess: other portions of the examination. If abnormalities are While it is rarely pointless to perform a basic screen of found, or if a patient’s responses to the initial tests are light touch sensation (at minimum), if a patient does not inconsistent, further testing (vibration, position sense, present with a condition that affects the nervous system, and temperature) should be performed. Persons who are has no reported symptoms of somatosensory involve- at risk for or who have been diagnosed with a condi- ment, and has no risk factors for somatosensory loss, a tion that impairs distal extremity sensation (such as dia- screen is not necessary. betes) should always be tested for protective sensation.  Fundamental Concepts 363 Section 2: Spinal Nerve Root Integrity and tingling (paresthesias) through the lateral aspect of the INTRODUCTION foot. Based on this description of the type and location of There are 31 pairs of spinal nerves that exit the spinal cord the pain, there is good evidence for nerve root dysfunction through the intervertebral foramen at each vertebral level: at the level of S1. Further investigation of the dermatome 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. (sensation at the lateral aspect of the foot), myotome (ankle At each vertebral level, a dorsal (posterior) root and a ven- eversion strength), and the deep tendon reflex (Achilles ten- tral (anterior) root emerge from the spinal cord and join don) associated with this spinal level would then clearly be to form what is known as a nerve root (see FIGURE 10-16). warranted. The dorsal root contains afferent sensory fibers, and the In the neurologic population, dermatomes and myo- ventral root contains efferent motor fibers. Thus, each spi- tomes might be utilized when examining patients who nal nerve root has a sensory and a motor component.3,36,37 have experienced a spinal cord injury (SCI).36 Because The sensory distribution of any given nerve root is defined the dysfunction (injury to the spinal cord itself) is within as a dermatome while the motor distribution of that root is the central nervous system, this would be considered an defined as a myotome. upper motor neuron lesion. In a complete SCI, all sensa- Dermatomes and myotomes are presented together in tion and volitional motion is absent below the level of the this section because both are specific to individual nerve lesion. Although this spinal level will probably be identified roots and these tests are typically performed together. Deep through diagnostic testing well before a patient is seen in tendon reflexes, presented in the following section, are often physical therapy, dermatome and myotome testing for nerve tested with dermatomes and myotomes to further assess the roots above, at, and below the lesion can identify sensory possibility of nerve root dysfunction. Although dermatome and motor deficits specific to each patient. Patients with and myotome assessments are likely used more frequently incomplete SCIs, where a lesion may have affected only in patients with orthopedic versus neurologic dysfunction, part of the spinal cord at any one level, may have sensory information gleaned from these tests can provide useful and motor deficits that are quite variable. A patient with an diagnostic data for both populations. incomplete lesion at T12 may have some ability to flex and Testing of dermatomes and myotomes is performed for adduct the hips, both of which rely on innervation from specific reasons. In an orthopedic setting, these tests would the upper lumbar spinal levels. Dermatome and myotome be conducted if a clinician suspected, or wanted to rule out, testing in these patients may help to “map” the areas found a nerve root dysfunction, such as compression of the root to be normal, diminished, and absent. from a bulging or herniated vertebral disc. Because the dys- function (compression of the nerve root itself) is peripheral to the spinal cord, this would be considered a lower motor FUNDAMENTAL CONCEPTS neuron lesion (involving the peripheral nervous system). Closely listening to the signs and symptoms described by Dermatomes your patients may provide key information that can add A dermatome is defined as the area of skin, often resem- evidence to your clinical decision to assess dermatomes bling a linear strip, supplied by a single nerve root. While and myotomes. Consider a patient who has a chief com- the strips corresponding to each nerve root are fairly con- plaint of right leg pain. It is described as “shooting” pain sistent from person to person, there can be considerable that travels from the right buttock, down the back of the overlap.38 This is most easily understood when considering upper leg and outside of the lower leg and foot, ending at the complexity of a nerve plexus (such as the brachial plexus the little toe. The patient also reports frequent numbness or the sacral plexus) where, after exiting the spinal cord as roots, the nerves intermingle with other nerves, joining and separating until they finally become a terminal branch some distance from the root itself (see FIGURE 10-17). In this Ventral root joining and separating, normal human variability suggests Spinal nerve that two people will have a slightly different distribution, and this may explain why published sources illustrating the human dermatomes are quite variable. Many of the dermatome maps found in popular text- Dorsal root ganglion books are based on two sources39,40 published prior to Dorsal root 1950.41 Recently, the accuracy of these maps has been ques- Spinal cord tioned,38,41 and there does not seem to be consensus about FIGURE 10-16 Cross section of the spinal cord which map is most accurate. To be consistent with the der- demonstrating the (dorsal) afferent and (ventral) efferent matome map most frequently used in physical therapy text- roots that form the spinal nerve root. books,41 the map developed by Keegan and Garrett40 is used Adapted from Siegel A, Sapru HN. Essential Neuroscience. Baltimore: Lippincott Williams & Wilkins; 2006. in this text (see FIGURE 10-18). While lack of a clear pattern 364 CHAPTER 10 Neuromuscular Examination L2 L3 Femoral nerve L4 Superior gluteal nerve Inferior gluteal L5 Deep peroneal nerve nerve Superficial Peroneus longus S1 peroneal and brevis muscles Sciatic S2 Tibial nerve FIGURE 10-17 Progression of spinal nerves to terminal peripheral branches (example from the lumbosacral plexus; contributions of L5 and S1 nerve roots to eventually form the superficial peroneal nerve are highlighted). may initially prove frustrating as you attempt to learn the sensory distribution nerve roots, it must be emphasized that PROCEDURE Dermatomes and myotomes that affect the upper and dermatome testing will only offer one small portion of the lower extremities tend to be the most frequently tested and overall evidence you will collect in your physical examina- clinically useful when attempting to localize pathology in a tion. Definitive conclusions should never be based on find- nerve root. As the testing procedures are discussed, please ings from dermatome testing alone. refer to TABLE 10-1 for sensory and motor locations for root- specific tests. Dermatomes and Shingles The varicella-zoster virus (which causes shingles) lies dormant in the sensory ganglion of spinal nerve roots after one has had chickenpox. Dermatomes When this virus is activated in one or more nerve roots, painful skin lesions develop Dermatome testing often is performed using light finger along the dermatome distribution.42 touch of the examiner. Cotton balls or pieces of gauze also may be used. Based on the knowledge that there is con- siderable overlap in the dermatomal strips, the tested area Myotomes should be limited to the region of least overlap. These areas A myotome is defined as a group of muscles supplied by are indicated with an X in Figure 10-18 and also correspond a single nerve root. Most muscles in the human body are to the areas described in Table 10-1. If diminished sensa- supplied by more than one nerve root; therefore, a lesion tion is identified, it may then be possible to map out the or compression at one root would likely only lead to weak- full area of reduced sensation through further sensation ness of that muscle, not complete paralysis. This differs testing within the dermatome. Other types of sensory tests, from what might be found with a peripheral nerve lesion, such as comparison of sharp versus dull stimulus or tem- which could, in fact, render a muscle unable to contract.3 perature differentiation, also may be used in dermatome FIGURE 10-19 illustrates this difference. In this example, assessment.43 because the C7 nerve root is a major source of innervation The patient should be in a comfortable position that to the triceps muscle, injury at the C7 level might lead to allows for easy access to the required areas of skin. Der- notable weakness in elbow extension. Because the triceps matome testing should not occur through clothing. Before is also innervated by C6, C8, and T1, the muscle would beginning, the patient should be educated about the pur- still be able to produce force but at a diminished level. pose of the test (“I’m going to test your ability to sense my On the other hand, the radial nerve (a peripheral branch touch at several places on your arms/legs”). In addition, the formed by C5–C8 and T1) is the sole nerve supply to the patient’s eyes should be closed for the duration of the test to triceps, and injury to the proximal radial nerve may lead eliminate visual input that could skew his or her perception to triceps paralysis. about the presence or location of the touch stimulus. Because muscles are supplied by more than one nerve If there is one suspected nerve root, the minimum root, identifying the source of observed weakness can some- assessment should include the dermatome above, at, and times be challenging. Luckily, the motor distribution of below the suspected level. This will help to ensure that any nerve roots seems to be less controversial than the sensory identified sensation deficit is truly related to a nerve root distribution. However, given normal human variants and and not the result of a random anomaly of the patient’s sen- the known multiroot innervations for each muscle, clini- sation on that limb. cal diagnostic decisions should not be based solely on the The touch should be light enough that contact with results of myotome testing. the epidermis is made but the skin is not indented. The  Procedure 365 right and left sides should be tested simultaneously to allow the patient to compare an affected to an unaffected side (between-limb assessment) (see FIGURE 10-20). If a spe- cific spinal level is identified as impaired when comparing right to left, then you may also choose to compare nerve C3 root levels unilaterally (within-limb assessment). Consider C4 × the following example: C5 C3 C6 × C4 Based on a patient’s history and examination findings C5 thus far, pathology at the right L4 level is suspected. The C7 T1 right and left dermatomes are simultaneously assessed C8 T1 T2 at L2, L3, L4, L5, and S1 (between-limb assessment test- T2 ing two levels above and two levels below the suspected × root dysfunction). The patient reports diminished sen- sation in the right L4 distribution versus the left. Con- × firmative testing might then occur by performing a within-limb assessment, asking the patient to compare the sensation felt when testing the dermatome above, at, C6 and below the suspected dysfunctional level. C5 L1 L2 Myotomes L3 The concepts and techniques used to test myotomes are L4 nearly identical to those used for assessing gross strength. L5 The patient is required to isometrically hold a test posi- C6 × tion against a strong resistive force applied by the exam- S3 C6 L1 C8 × iner (break test).43 The testing is specific to joint motions as C7 C8 S1 S2 S2 × × C7 opposed to individual muscles (although suspicious find- S3 ings can be further investigated through isolated muscle S4 × tests). One minor difference is that, because muscles are L2 S5 L1 supplied by more than one nerve root, it takes longer for × the muscle to fatigue if only one root is functioning abnor- L2 L3 mally. Therefore, the resistance you apply should be held for × a minimum of 5 seconds.3 As with gross strength testing, if the patient cannot hold the position against your resistance, you should confirm the L4 reason (such as pain or weakness). Although pain might L3 be a patient’s chief complaint in the presence of nerve root pathology, the source of the pain is neural and not contractile tissue. Therefore, weakness is a more likely finding than pain if, in fact, the pathology lies at the nerve root. For example, consider a patient with a disc bulge that is compressing the L5 left C6 nerve root. The patient reports a burning-type pain L4 in the lateral forearm into the thumb and finds it difficult to lift heavy objects. When the C6 myotome (elbow flexion) is tested, weakness is noted, but the patient denies pain with S1 the test. This is because the source of the pain is in the cervi- cal spine, not in the muscles that flex the elbow. × × At minimum, the myotome above, at, and below the suspected level should be assessed. Similar to dermatome L5 L5 testing, comparison can be made between limbs as well as L4 × within limbs. Because some muscle groups may naturally produce more force than others, interpretive caution should FIGURE 10-18 Body map of dermatomes (specific skin be taken during within-limb comparison. For example, in a regions to test within each dermatome indicated with an X). healthy limb, the force one can produce to extend the great toe (L5 myotome) is naturally much less than the force that can be produced by the myotomes above and below that level (L4: ankle dorsiflexion; S1: ankle plantar flexion). These inherent differences should always be considered. 366 CHAPTER 10 Neuromuscular Examination Lateral cord Musculocutaneous nerve C5 Posterior cord C6 Median nerve C7 C8 T1 Axial nerve Medial cord Ulnar nerve Lateral head Radial nerve Triceps brachii muscle Long head Medial head of triceps brachii Sensory branches Brachioradialis Posterior brachial cutaneous nerve Extensor carpi radialis longus Anconeus Posterior antebrachial cutaneous nerve Deep radial nerve Extensor carpi radialis brevis Extensor digitorum communis Extensor digiti quinti proprius Extensor carpi ulnaris Supinator Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Superficial radial nerve Extensor indicis proprius FIGURE 10-19 Comparison of an injury to the C7 nerve root versus an injury to the radial nerve (a branch from the C7 root) and the resulting motor loss. Because the radial nerve is supplied by C5, C6, C7, C8, and T1, an injury to the C7 nerve root (indicated by the X in the illustration) would lead to diminished strength in the upper extremity extensor muscles. An injury to the radial nerve itself (indicated by the // in the illustration) would likely lead to complete paralysis of the upper extremity extensor muscles. Instructions given to the patient should be clear and consistent. Using terminology such as “Don’t let me move you” or “Hold as strong as you can” is appropriate. Even though these instructions mean the same thing, you are encouraged to use only one phrase consistently to minimize the chance of confusion. FIGURES 10-21 through 10-33 illustrate the sug- gested patient positions and examiner hand placements for each myotome test listed in Table 10-1. Modifications may be made to these positions as needed for patient FIGURE 10-20 Bilateral assessment of the L4 dermatome. comfort.  Procedure 367 TABLE 10-1 Spinal Nerve Roots and Their Corresponding Dermatomes and Myotomes Dermatome Myotome Focal Area of Skin to Test Resisted Joint Motion to Test Root (within the larger dermatome) (alternate test in italics) C3 Lateral neck Cervical lateral flexion C4 Over clavicle Shoulder elevation (shrug) C5 Lateral upper arm (deltoid insertion) Shoulder abduction C6 Thumb Elbow flexion; wrist extension C7 Middle finger Elbow extension; wrist flexion C8 Medial border of hand; little finger Thumb extension; finger flexion T1 Medial forearm Finger abduction and adduction T2 Medial upper arm close to axilla None L1 Anterior groin None L2 Middle to upper anterior thigh Hip flexion L3 Middle to lower medial thigh Knee extension L4 Medial aspect of foot to great toe Ankle dorsiflexion; ankle inversion L5 Central dorsum of foot to middle toe Great toe extension S1 Lateral aspect of foot and ankle Hip extension; ankle plantar flexion*; ankle eversion S2 Middle of posterior thigh Knee flexion; ankle plantar flexion *Because weakness in ankle plantar flexors may be difficult to detect with manual resistance, the patient may be asked to perform a single- leg heel raise (comparing the affected limb to the unaffected limb). Data from Magee D. Cervical spine. In: Orthopedic Physical Assessment. St. Louis, MO: Saunders Elsevier; 2008:130–202; Magee D. Lumbar spine. In: Orthopedic Physical Assessment. St. Louis, MO: Saunders Elsevier; 2008:515–615; Petty N. Neuromusculoskeletal Examination and Assessment: A Handbook for Therapists. 3rd ed. Philadelphia, PA: Elsevier; 2006; and Dutton M. The nervous system. In: Dutton’s Orthopedic Survival Guide: Managing Common Conditions. New York, NY: McGraw-Hill Medical; 2011:53–106. FIGURE 10-21 Myotome test for C3. FIGURE 10-22 Myotome test for C4. 368 CHAPTER 10 Neuromuscular Examination FIGURE 10-23 Myotome test for C5. FIGURE 10-24 Myotome test for C6. FIGURE 10-25 Myotome test for C7. FIGURE 10-26 Myotome test for C8. FIGURE 10-27 Myotome test for T1.  Procedure 369 FIGURE 10-28 Myotome test for L2. FIGURE 10-29 Myotome test for L3. FIGURE 10-30 Myotome test for L4. FIGURE 10-31 Myotome test for L5. FIGURE 10-32 Myotome test for S1. FIGURE 10-33 Myotome test for S2.  Fundamental Concepts 371 Section 3: Deep Tendon Reflexes INTRODUCTION Sensory (afferent) neuron If a physician has ever tapped your knee with a small Muscle hammer-like instrument, your deep tendon reflexes (DTRs) spindle have been tested. DTRs can provide insight into the integ- rity of the peripheral and central nervous systems. As with dermatomes and myotomes, DTRs are often utilized in patients presenting with musculoskeletal conditions. In Gastrocnemius fact, these three tests are often performed in succession to muscle provide multilayered data about a particular spinal nerve. Motor (afferent) neuron Unlike dermatomes and myotomes, there is not a specific DTR for each spinal level. However, there are several com- Soleus muscle mon DTRs used in the clinical setting to evaluate both the cervical and lumbar regions. Tap slightly on stretched tendon Testing of DTRs can be performed as a very quick Achilles screen of the nervous system, which is the typical rationale tendon for their inclusion in routine physical examinations per- formed by physicians.5,15 They can also be used as one of many tools for diagnosing central (upper motor neuron) and peripheral (lower motor neuron) nervous system disor- ders.44,45 In addition to injury or disease, there are a number of variables that can affect an individual’s DTR response, including an inability to relax, mood state, certain medica- FIGURE 10-34 The deep tendon (stretch) reflex. Schema tions, or neurochemical imbalance.45,46 There also is a range for activation of muscle spindle through the Achilles ten- don tap with resulting contraction of the gastrocnemius. of normal DTR responses; some individuals have naturally Data from Chelboun G. Muscle structure and function. In: Levangie P, Norkin C, eds. Joint strong DTRs while others have naturally weaker ones.44 Structure and Function: A Comprehensive Analysis. 5th ed. Philadelphia, PA: F.A. Davis; 2011. For these reasons, clinical decisions should never be based solely on the findings from DTR tests.3 The results should be bundled with other clinical tests to build a strong case for any diagnosis considered. Because some individuals naturally possess some degree of hyper- or hyporeflexia, the presence of a 1+ or a FUNDAMENTAL CONCEPTS 3+ does not necessarily indicate pathology, especially if elic- A DTR is a monosynaptic reflex, meaning that there is one ited bilaterally and without supportive evidence (additional afferent (sensory) component and one efferent (alpha motor) sensory or motor dysfunction).3,46 Side-to-side differences component that communicate via one synapse within the should be further investigated for the presence of pathology. anterior horn of the spinal cord (see FIGURE 10-34).44,45 The afferent nerve has a direct connection to a muscle spin- Hypotonic DTRs Abnormally hypotonic DTRs frequently result from injury dle within the target muscle. When a tendon is tapped, a or compression along the nerve pathway, including at the quick stretch occurs in the muscle (thus, a DTR is actually nerve root. At the nerve root level, a common source of a stretch reflex), which is a