Achilles Reflex

A Quick Guide to the Achilles Reflex

The Achilles reflex is a stretch reflex which means it is a response to a muscle being stretched. All reflexes are involuntary responses that can be useful for conducting certain medical investigations.  It is possible to test this reflex of the Achilles tendon by striking the tendon when the foot is dorsi-flexed. This term dorsi-flexed, means that the angle between the foot and the leg has been reduced.  In other words, if you bend your foot towards your leg it is said to be dorsi-flexed. When the Achilles tendon is struck while in this position the foot should react by jerking of the plantar surface; this is the part of the foot that faces downwards.  This reflex is considered important for a number of reasons which we will now examine.

Checking the Achilles reflex is a method used by medical professionals to make a diagnosis because it allows them to check for nerve damage or damage to neurons on the spinal cord.  It is also the case that there are certain medical conditions that will mean the reflex might be absent and these include; alcoholism, chronic diabetes, subarachnoid hemorrhages, and neurosyphilis.

With alcoholism medical professional will regularly check this reflex to monitor what is happening with the patient, and to check for improvements in their neurological function. With diabetic patients the Achilles reflex can be delayed or absent because of damage to the peripheral nervous system (neuropathy) that occurs when the condition is serious. Neurosyphilis is an infection of the spinal cord and brain; it is caused because a person is suffering from untreated syphilis. When the spinal cord and brain is infected it can affect the tendon reflex.  A subarachnoid hemorrhage is when blood enters the subarachnoid space which surrounds the brain. This is a very life threatening situation that can also show up in the reflexes.

As well as having an absent or reduced Achilles reflex it is also possible for there to be an exaggerated reflex. There a couple of possible causes for this; it could be that there is a lesion on the motor tracts, or it could also mean that there is some type of cervical cord compression.

When testing for the Achilles reflex the usual procedure is for the physician to ask the patient to have the patient with their legs dangling while sitting on a chair or bed. They will need to remove their shoes and socks for this test. The doctor will begin the test by grabbing onto the foot and moving it to the dorsi-flexion position (as mentioned above). The physician will then tap on the tendon with a small hammer; don’t worry it’s not painful.  The foot should automatically respond by contracting the plantar region.

There has been quite a lot of research involving the use of the Achilles reflex. The reason for this is that it is a good method of providing data when monitoring the performance of individuals with certain medical conditions who may be taking part in research.

As you can see from the above there are some very good reasons as to why your doctor might want to check your Achilles reflex. It is a good way of finding out about things that are going on in your body, or monitoring conditions that can be deteriorating or improving. The great thing about this test is that it is non-invasive and can be conducted quickly. There are no real risks associated with this test and other than a hammer there is no expensive equipment to be used, and best of all is that it involves minimal discomfort to the patient.