Plexopathy

The nerve roots emerging from the left and right sides of the spinal cord do not extend straight into the limbs. Several nerves come together, intermingle, and divide again, passing through a network-like region called a nerve plexus. Think of it as an intermediate hub where several electrical wires meet at a switching device before separating again in their respective directions.

The body has several nerve plexuses, but two are discussed most often in relation to the limbs.

• Brachial plexus — Nerve roots from the lower neck come together to form the nerves supplying the shoulder, arm, and hand. They pass behind the collarbone and toward the armpit.
• Lumbosacral plexus — Nerve roots from the lumbar and sacral regions come together to form the nerves that pass through the pelvis and into the leg.

Plexopathy refers to a condition in which nerves are affected in this region. It is not the name of one specific disease, but a term indicating where a problem has occurred.

Because several nerve roots and peripheral nerves are intertwined in a plexus, symptoms often do not fit neatly within the territory of a single nerve. Here are some examples.

• You may experience paresthesia or an electric, prickling sensation over a broad area of an arm or leg.
• Pain that begins around the shoulder or buttock may extend into the arm or leg.
• You may notice hypoesthesia in a hand or foot.
• You may feel weak when lifting objects, raising an arm, walking, or climbing stairs.

Similar symptoms can arise from a nerve root, a plexus, or an individual peripheral nerve, so it is difficult to pinpoint the location from the sensations alone. A healthcare professional therefore considers both where sensation has changed and which muscles have changed in strength to help locate the problem.

The sensations can overlap with those of cervical radiculopathy or other problems involving peripheral nerves, so the boundaries are not as clear-cut as bodily sensations might suggest.

Plexopathy is discussed in a variety of contexts. Reported causes in the literature include trauma that forcefully stretches the arm or shoulder, such as a traffic accident or fall; changes after surgery or radiation therapy; inflammation affecting nerves; and a nearby mass pressing on nerves. Brachial plexus injuries caused by stretching of the nerves around the shoulder and arm during birth are also well known.

It cannot be assumed that a particular everyday movement or posture causes plexopathy. However, if there has been a situation that placed considerable force on the shoulder and arm, such as an accident that forcefully pulled one shoulder or carrying a heavy load on the shoulders, telling a healthcare professional what happened can help them locate the problem.

• Keep a record of when symptoms appeared. Noting when they started, which movements bring them on, and which areas have changed can help a healthcare professional locate the problem. Try using a pain diary.
• Keep your limbs moving without overexerting yourself. Rather than forcing the weaker side to work, gentle movement within a comfortable range helps keep the joints from becoming stiff.
• Try to avoid positions that cause pressure. If you have habits that put prolonged pressure on the shoulder and arm, such as pressure from bag straps or pillows, or lying while leaning against something, try changing them.
• Compare your left and right sides. Comparing grip strength, arm raising, and how you walk on each side can make changes easier to notice.

If an arm or leg suddenly becomes weak, sensation progressively diminishes, or a limb on one side becomes noticeably thinner, consult a healthcare professional as soon as possible. The same applies if new tingling appears after an accident, surgery, or radiation therapy.