Back pain can be caused by a number of different injuries and conditions, and different causes of back pain affect different systems of the body: muscular, skeletal, central nervous, etc. That’s why physicians will often perform a variety of tests aimed at finding weaknesses in one or all of these systems in order to find and confirm a diagnosis.
An accurate history and physical exam will be the first step toward coming to a firm diagnosis. The history and physical examination provide 90 percent of the necessary information to determine the cause of the pain. Tests that target the patient’s reflexes, nerves and muscular strength are almost always a component of the physical exam. These tests are very helpful in indicating problems like herniated discs, sciatica, pinched nerves and other spinal conditions.
How does the doctor test reflexes and muscle strength?
During the physical exam, the physician may ask you to:
- Walk on your toes
- Walk on your heels
- Walk on the soles of your feet
These tests help gauge the strength in your leg muscles. They can also help the physician tell if there is nerve damage as the result of a degenerative spinal abnormality.
For the reflex test, the physician will gently strike the knee and the back of the heel with a small rubber hammer. If your reflexes are normal, the hammer strike should cause a tell-tale twitch in the leg being tested.
When do reflex and muscle tests indicate nerve damage
Reflexes test neural function. Reflexes may be depressed or exaggerated. When nerve dysfunction exists, the size of the reflex response helps to indentify where the dysfunction originates. For example, exaggerated response may indicate spasticity caused by a central nervous system lesion, whereas if the patient has trouble rising to their toes or walking on their heels, or if the reflex test shows little or no reaction, this may point to nerve damage, or possibly a compressed nerve root due to a prolapsed disc, bulging disc, or a peripheral nerve injury.
Each nerve root in our spine contains two fibers: a sensory fiber and a motor fiber. The sensory fiber supplies sensation to a certain zone of skin on your body, called a dermatome. Similarly, the motor fiber is responsible for allowing certain muscle groups to move. The specific group of muscles supplied by the same nerve root is called a myotome. If the physician detects weakness in a certain myotome, it may indicate that the corresponding nerve is impaired in some way, usually due to a disc injury that is causing the nerve root to be compressed.