Differential diagnosis for CRPS sometimes involves ruling out a pinched nerve. Pinched nerves occur when surrounding tissues, such as bones, muscles, or tendons, place too much pressure on a nerve, resulting in nerve compression or nerve entrapment. Conditions like diabetes, osteoarthritis, and obesity, as well as repetitive motions and overuse, can increase the risk for nerve disorders (neuropathies), including pinched nerves.
Nerve compression can affect any nerve in the body and cause symptoms similar to those caused by CRPS. Compression of one of the nerves of the spine (called spinal nerves) can cause pain that radiates (spreads) from the neck, upper back, or lower back to the arm(s) or leg(s); decreased sensation; numbness and tingling; and muscle weakness.
Compression of a spinal nerve can result from a herniated disc, arthritis of the spine, spinal stenosis (narrowing of the spinal canal), or bone spurs (bony protrusions in the spine). Conditions that involve nerve compression in other areas of the body include carpal tunnel syndrome (caused by a compressed nerve in the wrist), Morton's neuroma (caused by nerve compression in the foot), and cubital tunnel syndrome (caused by a compressed nerve in the elbow).
Diagnostic tests that may be used to detect a pinched nerve include electromyography (EMG), nerve conduction velocity (NCV) studies, and imaging tests (e.g., computed tomography, magnetic resonance imaging). EMG and NCV help evaluate nerve and muscle function. CT scan and MRI scan are used to create detailed images of internal tissues to help locate areas of nerve compression.
Treatment for a pinched nerve depends on the cause and severity of the condition. In many cases, conservative treatment, such as resting the affected, applying ice, and taking medications (e.g., nonsteroidal anti-inflammatory drugs [NSAIDs], muscle relaxants) helps to reduce pinched nerve symptoms. Physical therapy, stress management techniques, chiropractic adjustments, and cortisone injections also may be helpful. In severe cases, surgery to relieve pressure on the nerve may be necessary. The type of surgery performed depends on the location of the pinched nerve.