Entrapment Neuropathy: More Than Just Carpal Tunnel!
Last week we discussed carpal tunnel syndrome (CTS), one of the most common forms of neuropathy affecting a single nerve (mononeuropathy). What many of your patients might not know is that carpal tunnel syndrome is only one of the entrapment neuropathies common in the upper limbs. The other entrapment neuropathies are not as well-known in the mainstream as CTS, and so patients who suffer from nerve symptoms in their forearms and hands frequently jump to conclusions! We’re here to help you set the record straight.
An entrapment neuropathy, also called nerve compression syndrome, occurs when a nerve is wedged or “pinched” against a bone, inflamed muscle, or other internal mechanism in the arm. Aside from the median nerve (the one associated with CTS) there are two main nerves that help to control the arm and hand: the radial nerve and the ulnar nerve. Both are susceptible to compression, and the results can be painful!
Entrapment occurs under a number of conditions, most commonly:
- When there is an injury originating at a patient’s neck or a disease of their cervical spine
- When your patient’s elbow has been injured due to fractures or improper use
- When your patient’s wrist has been injured due to fractures or Guyon canal alignment problems
- An aneurysm or thrombosis in the arteries
- Factors commonly associated with peripheral neuropathy, such as diabetes, rheumatism, alcoholism, or infection
The radial nerve runs the length of the arm, and is responsible for both movement and sensation. Radial neuropathy usually occurs at the back of the elbow, and can present with many of the common symptoms of neuropathy such as tingling, loss of sensation, weakness and reduced muscle control (in this case, your patient will often complain of difficulty in turning the palm upwards with your elbow extended).
A number of palsies affect the radial nerve, such as:
- Saturday night palsy (also called Honeymooner’s palsy), where the radial nerve is compressed in the upper arm by falling asleep in a position where pressure is exerted on it by either furniture or a bed partner
- Crutch palsy, where the nerve is pinched by poorly-fitted axillary crutches
- Handcuff neuropathy, wherein tight handcuffs compress the radial nerve at the wrists
Two main conditions affect the ulnar nerve: Guyon’s canal syndrome and cubital tunnel syndrome. Guyon’s canal syndrome is almost exactly the same in symptoms as carpal tunnel syndrome (pain and tingling in the palm and first three fingers), but involves a completely different nerve. Guyon’s canal syndrome is caused by pressure on the wrists, often by resting them at a desk or workstation, and is frequently experienced by cyclists due to pressure from the handlebars.
Nearly everyone has experienced cubital tunnel syndrome: it’s the “dead arm” sensation we’ve all felt when we wake up after sleeping on top of our arm! Sleeping with the arm folded up compresses the ulnar nerve at the shoulder, causing it to effectively “cut off” feeling to your arm. As you and your patients all probably know from experience, this sensation is unsettling but temporary.
Diagnosis for all compression neuropathies is fairly consistent. We advise a visual and tactile examination of your patient’s arms, wrists and hands, along with a test of the patient’s independent range of motion (as mentioned before, difficulty extending the elbow could indicate radial nerve damage). Blood or nerve tests can help establish underlying conditions that may contribute to neuropathy. The Tinel and Phalen tests will also help determine loss of dexterity and sensation that could indicate a compression neuropathy. MRI or x-ray scans are common to pinpoint the specific location of a compression. Contact NeuropathyDR® if you have any questions about your patient’s symptoms or the correct way to check for compression neuropathy.
Similar to carpal tunnel syndrome, most cases of entrapment neuropathy are mild. Treatment for these mild cases involves ice, rest, and a change in habits of motion or stress that are causing the symptoms. For more severe cases, you might choose to prescribe painkillers or anti-inflammatories, and in extreme cases, a surgical solution is sometimes justified.
If you would like to know more about how to treat patients who suffer from compression syndrome or other types of neuropathic pain, NeuropathyDR® can help! As a training resource we can help you treat your patients, as well as help the patients you can benefit find you!