NERVE COMPRESSION SYNDROMES
Nerve compression is characterized by numbness and tingling. It can also cause shooting pain. Just like muscles, tendons, and ligaments, nerves depend on circulation. When a nerve is pressed or squeezed, the circulation is impaired, and the nerve goes to sleep. Nerves send sensations and motor commands back to the brain, so when a nerve is not receiving adequate circulation, you get that awful pins-and-needles feeling. The pain can be shooting or localized, mild or severe, constant or intermittent. In the case of longstanding nerve compression from cumulative damage, the pain may wake you up at night.
Nerves of the Arm
The nerves that give sensation and movement to the arm start in the brain, travel down the neck, and join in a neat little bundle under the collarbone. From there, they travel into the armpit before they branch off into lots of smaller nerves that you will not need to learn about here. You do, however, need to know about the three main nerves: radial, median, and ulnar.
The radial nerve provides muscle strength and sensation to the extensor muscles of the hand and wrist. It is the first nerve of the three to surface and does so about halfway between the armpit and the elbow on the underside of the arm. There are two places where the radial nerve is easily compressed: at the underside of the upper arm and at the armpit near the collarbone.
Resting your arm on the back of a chair or on your car window can cause pain or numbness in the dorsal side of the forearm (hairy side) where the radial nerve is near the surface. (See figure 11.19.) Prolonged compression of the radial nerve can lead to wrist drop. Carrying a heavy bag on your shoulder can also cause pain in the forearm if it compresses the radial nerve at the collarbone.
The median nerve provides movement to the flexor muscles of the hand and sensation to the thumb, index finger, middle finger, and adjacent half of the ring finger. The most common place for the median nerve to get compressed is in a tiny tunnel just near the carpal bones called the carpal tunnel.
Carpal tunnel syndrome (CTS) is caused by compression of the median nerve. It not a common condition in musicians, but it is common in teachers, who do a lot of computer keyboard work. Symptoms of CTS are pain, weakness, and numbness in the thumb and the first two fingers. Poor desktop ergonomics is a big contributor to this painful condition. Standing while using a laptop that’s sitting on a desk is one activity that compresses the median nerve. (See figure 11.20.) The median nerve can also be damaged by prolonged wrist extension or direct compression from resting your wrists on the edge of a table or keyboard. (See figure 11.21.)
FIGURE 11.19 Lean ing an arm over the back of a chair can cause compression of the radial nerve.
FIGURE 11.20 Prolonged extreme extension of the wrist can cause carpal tunnel syndrome.
FIGURE 11.21 Carpal tunnel syndrome can also be caused by direct and prolonged compression of the median nerve at the heel of the hand.
Mild CTS should be treated first with attention to the ergonomic setup of your workstations. (See chapter 4.) Pay attention to the flexion and extension of your wrist; any prolonged or repeated postures can be harmful to the circulation to the median nerve. Along with wearing a splint to immobilize the wrist, this may be enough to save you from joining the CTS club. Wear the splint at night and as much as you can during the day for the first two weeks. Carpal tunnel surgery can almost always be avoided by taking these early measures. If you get to the point where you are unable to grasp things or hold a coffee cup, you should see a doctor. Shooting pain in the forearms that wakes you up at night is also an indicator that you need to see a doctor.
The ulnar nerve sits in the groove of bone at the elbow. It supplies motor and sensory function to the pinkie and the adjacent half of the ring finger. H ave you ever smacked your elbow and had your pinkie and ring finger go numb? You found your ulnar nerve. Because it lies across a bone at the elbow, the ulnar nerve can be compressed when the elbow is bent during activities such as sleeping, playing the piccolo or the violin, or texting.
The ulnar nerve runs just underneath the skin from the elbow to the pinkie and is also easily compressed when leaning on the edge of a desk or even on the edge of a French horn bell. (See figure 11.22.) Ifyou can identify the activity that is making your fingers numb and stop doing it, the symptoms will probably go away within an hour. If they don’t, you may have cumulative damage, which takes longer to heal.
FIGURE 11.22 Habits such as resting the arm on the bell of a French horn or on the edge of a desk can cause numbness and pain from compression of the ulnar nerve.
If you sleep with your elbows flexed and your hands curled under your chin, as in figure 11.23, and then wake up with numb fingers, you’re compressing the ulnar nerve and the median nerve while you sleep. You should try to change your sleeping position; it may take a while, but it is important to do this if you are continually waking up with numb fingers or having symptoms of carpal tunnel syndrome.
FIGURE 11.23 Sleeping position can cause compression of the ulnar nerve in the elbow and the median nerve at the wrist.
FIGURE 11.24 An elbow wrap is a type of immobilization splint that can be worn while sleeping to avoid bending the elbow.
Issues concerning compression of the ulnar nerve can be resolved by identifying and changing the habit that is causing the nerve compression. If the offending habit is sleeping with bent elbows, you might want to try an elbow wrap. (See figure 11.24; the one in the picture came from the drugstore.)