| One-Minute Clinician

Understanding Peripheral Nerve Entrapment and Metabolic Disease

Peripheral nerve entrapment is predisposed many times by metabolic disorders. We know that when a nerve has a metabolic disorder such as diabetic peripheral neuropathy, it causes that nerve to function differently. It causes it to swell. It has a higher water content.  It becomes heavier. It has a larger cross-sectional diameter.  So where these nerves end up going through tunnels, they become entrapped. When they become entrapped in the tunnels,that causes a focal demyelination of the nerve, which then leads to nerve damage. By removing that source of focal entrapment, the nerve has the ability to regenerate itself and so patients are able to get restored sensation. Their pain reduction can be significant. Some studies show nearly 90 percent reduction in pain, and around 70 percent improvement in sensation.

Additionally, we’re finding that there are improvements in balance when patients can feel their feet on the floor. They have better proprioception.  Their brains know where they are in space, so that prevents a lot of falls. There are statistics that show many hip fractures are actually due to neuropathy. Patient can’t feel their feet on the floor and they end up falling. So we’re able to do a lot with peripheral nerve decompression from the standpoint of people with metabolic disease. In some ways, the geriatric patient is actually a better candidate for a peripheral nerve decompression compared to someone in the middle stages of life because we are able to improve their balance and prevent hip fractures and things that have a very high morbidity associated with them. So if the geriatric patient is in a good medical state--and we work up all these folks prior to any surgical nerve decompression--we don’t discriminate from an age standpoint.

About 3 percent of all patients that have undergone total knee arthroplasty end up with chronic pain post surgery. Interestingly enough, many times, that’s due to the fact that the common peroneal nerve at the side of the leg is stretched or pulled when they’re putting that knee implant in. It’s very easy to diagnose this because we can give a simple Lidocaine injection over the common peroneal nerve, and within three to five minutes come back and the patient reports “Yes, 100 percent of my pain is gone.”

Another example is an ankle sprain. Ankle sprains tend to cause entrapments of the common peroneal nerve up to the side of the leg just because of the mechanics that go on. So if you have someone that has an ankle sprain and they have continued pain more than three months after that ankle sprain, you need to start thinking about something other than the ligament and something other than a lateral ankle stabilization because it’s very likely they have either a superficial peroneal nerve or a common peroneal nerve, or actually both nerves entrapped.

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