Muscle reflex tests are used to indicate the health of the brain and nervous system and to help diagnose neuromuscular disease or nerve injury. A reflex is a nerve circuit between a muscle and the brain or spinal cord in the central nervous system. When you stimulate a muscle by lightly tapping or firmly stroking it, the sensory nerves signal the central nervous system, which causes the muscles to react. If there is nerve damage due to disease or injury, the muscle reflex may be abnormal or vary in strength. Muscle reflex tests include the familiar knee-jerk test and the brachio-radialis test at the elbow. The plantar reflex test assesses the muscle reflex at the sole of the foot. Neurologists commonly use this test to determine nerve damage. You can also perform this test at home; however, only a doctor can make a diagnosis by assessing reflex tests, medical scans and other tests.
Step 1
Ask the person on whom you are performing the plantar reflex test to sit comfortably on a high table or stool with his legs hanging over the edge and his feet dangling freely. Remove the shoes and socks from both his feet. Ask him to place his hands at his sides and hold the edge of the bed or stool to maintain his balance. Crouch down or sit on a low stool so that your are at the level of his knees and can reach the soles of his feet easily.
Step 2
Grasp one of his ankles gently but firmly with your non-dominant hand. Hold a blunt, pointed object, such as handle of a reflex mallet, in your dominant hand. Stroke the outer sole at the bottom of the foot beginning at the heel and moving forward to the base of the foot near the toes. You can also use your thumb or a knitting needle to stroke the foot. Use gentle, but firm pressure. Using too much force can cause the person to move his foot or toes, which can be mistaken for a reflex test response.
Step 3
Observe the toes of the foot as you stroke it. In normal, healthy adults all the toes should curl downwards as the muscles in this area flex in response to the stimulation. This is a positive plantar reflex and shows that the nerves to the muscles are intact. If the large toe extends outwards and upwards and the other toes spread out, this may be a sign of disease or damage to the brain or spinal cord. This abnormal response is called Babinski's sign.
Step 4
Repeat the test on the other foot. If you are concerned about the test results or if the person has any other symptoms, seek medical attention. A doctor or other trained medical professional must confirm muscle reflex tests.
Tips and Warnings
- In babies under the age of 1 to 1 1/2 years of age, the fibers in the brain and spinal cord are not yet completely covered with a protective myelin sheath that facilitates nerve messages. Hence, small children of this age will also show a positive Babinski sign; however, this is not a sign of disease. Healthy adults and children over age 1 1/2 should show a positive plantar reflex in which the toes curl under during stimulation at the soles of the feet.
- A doctor or trained medical professional should perform muscle reflex test. Although these tests are simple to perform, they require skilled assessment. Diagnosing potentially serious disease and damage to the brain and spinal cord, such as a stroke and multiple sclerosis, involves testing muscle reflexes in addition to a range of other tests.
Things You'll Need
- Reflex mallet or knitting needle
- Examination table or high stool
- Second person to help you
