Diabetic Neuropathy Diagnosis
Figuring Out Which Nerves Are Damaged
To diagnose diabetic neuropathy (also called diabetic nerve pain), your doctor will run through several exams and tests. These will all be used to help the doctor understand what nerves have been damaged and how extensive that damage is.
Your doctor will review your symptoms with you; this is the first step in trying to figure what kind of nerve damage you may have.
The different types of diabetic neuropathy affect different nerves, so you should be very specific when describing your pain or other symptoms.
Physical and Neurological Exams
During a physical exam, the doctor looks at your general physical condition. He or she will examine how well you can move. The doctor will also be looking for tender, sore, or painful areas. The physical exam allows the doctor to assess how your body is doing right now, so he or she will also check blood pressure, heart rate, and other basic health details.
As part of the physical exam, your doctor should thoroughly examine your feet, particularly if you have symptoms that line up with peripheral diabetic neuropathy. (In fact, people with diabetes should have regular foot exams to monitor foot health.)
Since diabetic neuropathy involves the nerves, the neurological exam is a crucial part of the diagnosis. This is where he/she may test your “sensations”—how well you’re able to feel certain stimuli—which is especially important in diagnosing peripheral diabetic neuropathy.
Different nerves are in charge of transmitting different sensory messages, such as temperature, touch, and vibration. Damaged nerves can’t transmit messages as well as they should, so these tests can be very helpful in narrowing down which nerves are affected.
Some possible sensation tests are:
- Temperature: The doctor will hold a very hot or very cold object near your skin to test how well you can feel temperature.
- Touch: He or she may actually prick you with a pin to see how well your touch nerve fibers are working. These are the fibers that not only tell you when you’ve come into contact with something, but they also tell you when you’ve been hurt (e.g., developed a sore or blister, or stepped on a shard of glass).
There is another way to test the touch nerves. The doctor may use a bendable nylon filament to test how much pressure you can feel. There are different-sized filaments that require different amounts of pressure to bend. By pushing a filament against the skin—on the foot, say—the doctor can measure how much force you can feel.
If you can feel a thin filament, then you can feel anything that touches your skin. If you can’t feel when a thicker filament is pushed against your skin, you probably have some degree of nerve damage.
- Vibration: Using a tuning fork, the doctor will test how well you can feel vibrations. The vibration nerves are important for balance.
The doctor may need to do some simple diagnostic tests to check how well the nerves are conveying messages. Nerve conduction velocity (NCV) is how fast nerve impulses travel, and it’s possible to measure that. Sometimes, noticing a slower NCV is the first sign of diabetic neuropathy because if nerves are damaged, they don’t convey messages as quickly.
Many conditions other than diabetes can cause neuropathy. Because other causes may need to be treated differently than diabetic neuropathy, it is important to do nerve testing in order to know for sure what type(s) of nerve pain you have.
An NCV test is done using electrodes that are patched onto the skin. These are placed along a nerve pathway—one at the top of the leg and one further down, for example. A tiny electrical current stimulates the nerve at one electrode, and then the second electrode captures the signal as it passes down the nerve. The test measures how long it took the signal to travel down the nerve.
An electromyography (EMG) test is often done in conjunction with an NCV test. It shows how well muscles are receiving signals from the nerves. Damaged nerves won’t send clear or consistent messages.
The EMG test uses very thin needles placed into the muscle(s) the doctor wants to test. Those needles are electrodes that measure activity. You’ll have to contract your muscles, and then that activity will be measured. If the muscle isn’t receiving good signals from the nerves, then that should show up on the EMG.
Other Possible Tests
Your doctor may run other tests not listed here—based on your specific symptoms and the type of diabetic nerve pain he or she thinks you have.
All tests will help the doctor pinpoint what kind of nerve damage you have, how it’s affecting your body, and how it can best be treated.
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