August 2, 2026
Just as compression of the peroneal nerve can cause the foot to drop, compression of the radial nerve in the arm can cause a similar problem called wrist drop, where a person loses the ability to lift their wrist and fingers upward against gravity. This nerve travels along the back of the upper arm in a shallow groove against the humerus bone, which leaves it particularly exposed to pressure injury.
The most classic and widely recognized cause is often nicknamed “Saturday night palsy,” which occurs when someone falls into a deep sleep with their arm draped over a hard surface, such as the back of a chair or their own body weight, for an extended period of time, usually after drinking alcohol or taking a sedating medication that dulls the normal urge to shift position. Other common causes include fractures of the humerus, since the radial nerve winds directly around this bone, improperly fitted crutches that place sustained pressure under the armpit, tight tourniquets used during surgery, and repetitive compression from certain occupational tasks.
Radial nerve palsy typically presents as an inability to lift the wrist or fingers against gravity, a pattern often described as the hand hanging limply from the wrist. Numbness frequently develops on the back of the hand, particularly in the web space between the thumb and index finger. Because the nerve also affects grip strength indirectly, by preventing the wrist from being stabilized during a grasp, some people notice their hand feels weak or clumsy even though the muscles that close the fist are usually still fully intact and functioning normally.
An accurate diagnosis starts with a physical exam to map out exactly which muscles are affected and to what degree. Electrodiagnostic testing, including EMG and nerve conduction studies, is often used to confirm the location and severity of the nerve injury and to help predict how likely the nerve is to recover on its own. In cases involving trauma or fracture, X-rays or an MRI may also be ordered to evaluate the bone and surrounding soft tissue for any structural cause of the compression.
Treatment depends heavily on the underlying cause and severity of the nerve injury. Many cases of compression-related radial nerve palsy, particularly those caused by a single episode of prolonged pressure, improve on their own with splinting to support the wrist, activity modification, and physical therapy over a period of weeks to months. When the nerve has been more significantly damaged, such as from a fracture or a penetrating injury, our specialists at IGEA Brain, Spine, Pain & Orthopedics can evaluate whether surgical exploration, decompression, or nerve repair is needed to restore function as fully as possible.
Nerve tissue regenerates slowly, often at a rate of about one millimeter per day, which means recovery from a more severe radial nerve injury can take several months. Physical therapy plays an important role throughout this process, both to maintain range of motion in the wrist and fingers while the nerve heals and to help retrain the muscles once signal begins returning. Regular follow-up with electrodiagnostic testing can also help track progress and confirm that the nerve is recovering as expected.
While most cases of radial nerve palsy develop gradually or following an obvious incident like falling asleep in an awkward position, sudden wrist drop following a fracture, deep laceration, or high-impact injury should be evaluated urgently, since prompt treatment in these situations can meaningfully improve the odds of full nerve recovery.
If wrist or finger weakness is affecting your daily activities, getting an accurate diagnosis early can make a meaningful difference in your recovery timeline.
Wrist drop can improve significantly with the right treatment plan, but getting an accurate diagnosis early makes all the difference. Call (866) 467-1770 to speak with one of our specialists, or Request a Consultation Online to schedule your visit.