Reflex Tests
Reflex Tests
Definition
Reflex tests are simple physical tests of nervous system function.
Purpose
A reflex is a simple nerve circuit. A stimulus, such as a light tap with a rubber hammer, causes sensory neurons (nerve cells) to send signals to the spinal cord. There, the signals are conveyed both to the brain and to nerves that control muscles affected by the stimulus. Without any brain intervention, these muscles may respond to an appropriate stimulus by contracting.
Reflex tests measure the presence and strength of a number of reflexes. In so doing, they help to assess the integrity of the nerve circuits involved. Reflex tests are performed as part of a neurological exam, either a "mini-exam" done to quickly confirm integrity of the spinal cord, or a more complete exam performed to diagnose the presence and location of a spinal cord injury or neuromuscular disease.
Deep tendon reflexes are responses to muscle stretch. The familiar "knee-jerk" reflex is an example of a reflex. This tests the integrity of the spinal cord in the lower back region. The usual set of deep tendon reflexes tested, involving increasingly higher regions of the spinal cord, includes:
- ankle
- knee
- abdomen
- forearm
- biceps
- triceps
- patellar
Another type of reflex test is called the Babinski test, which involves gently stroking the sole of the foot to assess proper development and function of the spine and cerebral cortex.
Precautions
Reflex tests are entirely safe, and no special precautions are needed.
Description
The examiner uses a reflex hammer or rubber mallet to strike different points on the examinee's body, and observes the response. The points chosen for eliciting reflexes are the tendons of specific muscles. Tapping specific sites is intended to provide a quick stretch to the muscle. Muscle spindles, or receptors, mediate the reflex lying within the muscle—not the site of the hammer strike. The examiner may position, or hold, one of the limbs during testing, and may require exposure of the ankles, knees, abdomen, and arms. Reflexes can be difficult to elicit if the individual being examined is paying too much attention to the stimulus. To compensate for this, that person may be asked to perform some muscle contraction, such as clenching teeth or grasping and pulling the two hands apart. When performing the Babinski reflex test, the examiner will gently stroke the outer soles of the person's feet with the mallet while checking to see whether or not the big toe extends out as a result.
| Muscle stretch (deep tendon) reflexes | ||
|---|---|---|
| Reflex | Stimulus | Response |
| Source: Rothstein, J.M., S.H. Roy, and S.L. Wolf. The Rehabilitation Specialist's Handbook. 2nd ed. Philadelphia: F.A. Davis Co., 1998. | ||
| Biceps | Tap biceps tendon | Contraction of biceps |
| Brachioradialis (periosteradial) | Tap styoid process of radius (insertion of brachioradialis) | Flexion of elbow and pronation of forearm |
| Jaw (maxillary) | Tap mandible in half-open position | Closure of jaw |
| Patellar | Tap patellar tendon | Extension of leg at knee |
| Tendocalcaneus | Tap Achilles tendon | Plantar flexion at ankle |
| Triceps | Tap triceps tendon | Extension of elbow |
| Wrist extension | Tap wrist extensor tendons | Extension of wrist |
| Wrist flexion | Tap wrist flexor tendon | Flexion of wrist |
Preparation
The examiner positions the person to be examined in a comfortable position, usually seated on the examination table with legs hanging free. There is no other preparation.
Aftercare
A reflex examination is not invasive. No care after the examination is required.
Complications
The pressure exerted by a reflex hammer is minimal and does not hurt the person being examined. A reflex examination is not invasive. There are no complications from performing the examination.
Results
Normal results
The strength of the response depends partly on the strength of the stimulus. For this reason, an examiner will attempt to elicit the response with the smallest stimulus possible. Learning the range of normal responses requires some clinical training. Responses should be the same on both sides of the body. A normal response to the Babinski reflex test depends upon the age of the person being examined. In children under the age of one and a half years, the big toe will extend out with or without the other toes. This is due to the fact that the fibers in the spinal cord and cerebral cortex have not been completely covered in myelin, the protein and lipid sheath that aids in processing neural signals. In adults and children over the age of one and a half years, the myelin sheath should be completely formed and as a result, all the toes will curl under (plantar flexion reflex).
KEY TERMS
Lesion— A pathologic change in body tissue.
Myelin— A substance composed largely of fat that constitutes the sheaths of various nerve fibers throughout the body.
Neurology— The study of nerves.
Abnormal results
Weak or absent response may indicate damage to the nerves outside the spinal cord (peripheral neuropathy), damage to the motor neurons just before or just after they leave the spinal cord (motor neuron disease), or muscle disease. Excessive response may indicate spinal cord damage above the level controlling the hyperactive response. Different responses on the two sides of the body may indicate early onset of progressive disease, or localized nerve damage, as from trauma. An adult or older child who responds to the Babinski with an extended big toe may have a lesion in the spinal cord or cerebral cortex.
Health care team roles
A reflex examination is usually conducted by a physician. Neurologists (doctors with specialized training in neurology) often perform reflex tests. Physician assistants, physical therapists, and nurses may also test reflexes as they examine or evaluate individuals.
Resources
BOOKS
Adams, Raymond D., Maurice Victor, and Allen H. Ropper. Adam's & Victor's Principles of Neurology, 6th ed. New York: McGraw Hill, 1997.
Aminoff, Michael J. Neurology and General Medicine, 3rd ed. London: Churchill Livingstone, 2001.
Bickley, Lynn S., Robert A. Hoekelman, and Barbara Bates. Bates' Guide to Physical Examination and History Taking. Philadelphia, PA: Lippincott, 1999.
DeGowin, Robert L., and Donald D. DeGowin. DeGowin's Diagnostic Examination, 7th ed. New York: McGraw Hill, 1999.
Seidel, Henry M. Mosby's Guide to Physical Examination, 4th ed. St. Louis, MO: Mosby Year Book, 1999.
Shwartz, Mark A., and William Schmitt. Textbook of Physical Diagnosis: History and Examination, 3rd ed. Philadelphia, PA: Saunders, 1998.
ORGANIZATIONS
American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. (913) 906-6000. 〈http://www.aafp.org/〉. [email protected].
American Academy of Neurology. 1080 Montreal Avenue, St. Paul, Minnesota 55116. (651) 695-1940. 〈http://www.aan.com/resources.html〉. [email protected].
American College of Physicians. 190 N Independence Mall West, Philadelphia, PA 19106-1572. (800) 523-1546 x2600 or (215) 351-2600. 〈http://www.acponline.org/cgi-bin/feedback〉.
OTHER
Explore Science. 〈http://www.explorescience.com/activities/Activity_page.cfm?ActivityID=38〉.
King's College (London). 〈http://www.umds.ac.uk/physiology/mcal/sreflex.html〉.
Loyola University (Chicago). 〈http://www.meddean.luc.edu/lumen/MedEd/medicine/pulmonar/pd/pstep56.htm〉.
University of Washington. 〈http://faculty.washington.edu/chudler/chreflex.html〉.
Washington University (St. Louis). 〈http://www.neuro.wustl.edu/neuromuscular/mother/reflex.html〉.
Reflex Tests
Reflex tests
Definition
Reflex tests are simple physical tests of nervous system function.
Purpose
A reflex is a simple nerve circuit. A stimulus, such as a light tap with a rubber hammer, causes sensory neurons (nerve cells) to send signals to the spinal cord. Here, the signals are conveyed both to the brain and to nerves that control muscles affected by the stimulus. Without any brain intervention, these muscles may respond to an appropriate stimulus by contracting. Newborn babies have a particular set of reflexes not present in older babies, children, and adults.
Reflex tests measure the presence and strength of a number of reflexes. In so doing, they help to assess the integrity of the nerve circuits involved. Reflex tests are performed as part of a neurological exam, either a mini-exam done to quickly confirm integrity of the spinal cord or a more complete exam performed to diagnose the presence and location of spinal cord injury or neuromuscular disease.
Deep tendon reflexes are responses to muscle stretch. The familiar knee-jerk reflex is an example; this reflex tests the integrity of the spinal cord in the lower back region. The usual set of deep tendon reflexes tested, involving increasingly higher regions of the spinal cord, are:
- ankle
- knee
- abdomen
- forearm
- biceps
- triceps
Another type of reflex test is called the Babinski test, which involves gently stroking the sole of the foot to assess proper development of the spine and cerebral cortex.
Description
The examiner places the person in a comfortable position, usually seated on the examination table with legs hanging free. The examiner uses a rubber mallet to strike different points on the individual's body and observes the response. The examiner may position, or hold, one of the limbs during testing, and may require exposure of the ankles, knees, abdomen, and arms. Reflexes can be difficult to elicit if the person is paying too much attention to the stimulus. To compensate for this, the person may be asked to perform some muscle contraction, such as clenching teeth or grasping and pulling the two hands apart. When performing the Babinski reflex test, the doctor will gently stroke the outer soles of the person's feet with the mallet while checking to see whether the big toe extends out as a result.
Risks
Reflex tests are entirely safe, and no special precautions are needed.
Normal results
The strength of the response depends partly on the strength of the stimulus. For this reason, the examiner will attempt to elicit the response with the smallest stimulus possible. Learning the range of normal responses requires some clinical training. Responses should be the same for both sides of the body. A normal response to the Babinski reflex test depends upon the age of the person being examined. In children under the age of one-and-a-half years, the big toe will extend out with or without the other toes. This is due to the fact that the fibers in the spinal cord and cerebral cortex have not been completely covered in myelin, the protein and lipid sheath that aids in processing neural signals. In adults and children over the age of one-and-a-half years, the myelin sheath should be completely formed, and, as a result, all the toes will curl under (planter flexion reflex).
Parental concerns
Parents should expect reflex tests to be included in every examination given to their children by a doctor or other healthcare provider. Reflex tests present no risks. Parents should only be concerned when they are told of abnormal reflex test results.
KEY TERMS
Babinski sign —Dorsiflexion (curling) of the big toe on stimulating the sole of the foot.
Neuron —The fundamental nerve cell of the nervous system.
See also Neonatal reflexes.
Resources
BOOKS
Bickley, Lynn S., and Peter G. Szilagyi. Bates' Guide to Physical Examination and History Taking, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2004.
Jarvis, Carolyn. Physical Examination and Health Assessment, 4th ed. Amsterdam, Netherlands: Elsevier, 2003.
LeBlond, Richard F., and Donald D. Brown. DeGowin's Diagnostic Examination, 8th ed. New York: McGraw-Hill, 2004.
Simel, David L. "Approach to the Patient: History and Physical Examination." In Cecil Textbook of Medicine, 22nd ed. Edited by Lee Goldman et al. Philadelphia: Saunders, 2003, pp. 18–22.
PERIODICALS
Berilgen, M. S., et al. "Effects of epilepsy on autonomic nervous system and respiratory function tests." Epilepsy and Behavior 5, no. 4 (2004): 513–6.
Calancie B., et al. "Tendon reflexes for predicting movement recovery after acute spinal cord injury in humans." Clinical Neurophysiology 115, no. 10 (2004): 2350–63.
Lefaucheur, J. P., and A. Creange. "Neurophysiological testing correlates with clinical examination according to fiber type involvement and severity in sensory neuropathy." Journal of Neurology, Neurosurgery, and Psychiatry 75, no. 3 (2004): 417–22.
Mold, J. W., et al. "The prevalence, predictors, and consequences of peripheral sensory neuropathy in older patients." Journal of the American Board of Family Practice 17, no. 5 (2004): 309–18.
Nadler, M. A., et al. "Cutaneomuscular reflexes following stroke: a 2-year longitudinal study." Journal of the Neurological Sciences 217, no. 2 (2004): 195–203.
ORGANIZATIONS
American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211–2672. Web site: <www.aafp.org/>.
American Academy of Neurology. 1080 Montreal Avenue, St. Paul, MN 55116. Web site: <www.aan.com/>.
American Academy of Pediatrics. 141 Northwest Point Blvd., Elk Grove Village, IL 60007–1098. Web site: <www.aap.org/default.htm>.
American Academy of Physical Medicine and Rehabilitation. One IBM Plaza, Suite 2500, Chicago, IL 60611–3604. Web site: <www.aapmr.org/>.
American College of Emergency Physicians. PO Box 619911, Dallas, TX 75261–9911. Web site: <www.acep.org/>.
American College of Physicians. 190 N Independence Mall West, Philadelphia, PA 19106–1572. Web site: <www.acponline.org/>.
American College of Sports Medicine. 401 W. Michigan St., Indianapolis, IN 46202–3233. Web site: <www.acsm.org/>.
International Brain Injury Association. 1150 South Washington St., Suite 210, Alexandria, VA 22314. Web site: <www.internationalbrain.org/>.
WEB SITES
"Moro reflex." MedlinePlus. Available online at <www.nlm.nih.gov/medlineplus/ency/article/003293.htm> (accessed December 22, 2004).
"Neuro-Ophthalmologic Disorders." The Merck Manual. Available online at <www.merck.com/mrkshared/mmanual/section14/chapter178/178b.jsp> (accessed December 22, 2004).
L. Fleming Fallon, Jr., MD, DrPH
Reflex Tests
Reflex Tests
Definition
Reflex tests are simple physical tests of nervous system function.
Purpose
A reflex is a simple nerve circuit. A stimulus, such as a light tap with a rubber hammer, causes sensory neurons (nerve cells) to send signals to the spinal cord. Here, the signals are conveyed both to the brain and to nerves that control muscles affected by the stimulus. Without any brain intervention, these muscles may respond to an appropriate stimulus by contracting.
Reflex tests measure the presence and strength of a number of reflexes. In so doing, they help to assess the integrity of the nerve circuits involved. Reflex tests are performed as part of a neurological exam, either a "mini-exam" done to quickly confirm integrity of the spinal cord, or a more complete exam performed to diagnose the presence and location of spinal cord injury or neuromuscular disease.
Deep tendon reflexes are responses to muscle stretch. The familiar "knee-jerk" reflex is an example; this reflex tests the integrity of the spinal cord in the lower back region. The usual set of deep tendon reflexes tested, involving increasingly higher regions of the spinal cord, are:
- ankle
- knee
- abdomen
- forearm
- biceps
- triceps
Another type of reflex test is called the Babinski test, which involves gently stroking the sole of the foot to assess proper development of the spine and cerebral cortex.
Precautions
Reflex tests are entirely safe, and no special precautions are needed.
Description
The examiner positions the patient in a comfortable position, usually seated on the examination table with legs hanging free. The examiner uses a rubber mallet to strike different points on the patient's body, and observes the response. The examiner may position, or hold, one of the limbs during testing, and may require exposure of the ankles, knees, abdomen, and arms. Reflexes can be difficult to elicit if the patient is paying too much attention to the stimulus. To compensate for this, the patient may be asked to perform some muscle contraction, such as clenching teeth or grasping and pulling the two hands apart. When performing the Babinski reflex test, the doctor will gently stroke the outer soles of the patient's feet with the mallet while checking to see whether or not the big toe extends out as a result.
Normal results
The strength of the response depends partly on the strength of the stimulus. For this reason, the examiner will attempt to elicit the response with the smallest stimulus possible. Learning the range of normal responses requires some clinical training. Responses should be the same for both sides of the body. A normal response to the Babinski reflex test depends upon the age of the person being examined. In children under the age of one and a half years, the big toe will extend out with or without the other toes. This is due to the fact that the fibers in the spinal cord and cerebral cortex have not been completely covered in myelin, the protein and lipid sheath that aids in processing neural signals. In adults and children over the age of one and a half years, the myelin sheath should be completely formed, and, as a result, all the toes will curl under (planter flexion reflex).
Abnormal results
Weak or absent response may indicate damage to the nerves outside the spinal cord (peripheral neuropathy ), damage to the motor neurons just before or just after they leave the spinal cord (motor neuron disease), or muscle disease. Excessive response may indicate spinal cord damage above the level controlling the hyperactive response. Different responses on the two sides of the body may indicate early onset of progressive disease, or localized nerve damage, as from trauma. An adult or older child who responds to the Babinski with an extended big toe may have a lesion in the spinal cord or cerebral cortex.
Resources
OTHER
Rathe, Richard. "The Neurological Exam." A Healthy Me Page. July 2, 1997. 〈http://www.ahealthyme.com〉.