Definition

Drop hand, or wrist drop, is a condition caused by radial nerve paralysis. The radial nerve branches out near the collarbone runs through the back of the upper arm and forearm, and controls the muscles responsible for lifting the wrist and fingers. Drop hand is a relatively common condition affecting people of all ages.

Causes

Drop hands can result from various conditions, including puncture wounds, external pressure, or nutritional deficiencies. A puncture wound in the shoulder area, just below the collarbone, can lead to a drop hand by severing the radial nerve. Fractures, such as a broken upper arm bone can also injure this nerve. Radial nerve injury may also occur from prolonged use of crutches, frequent leaning on the chin, or pressure on the armpit from the armrest of a chair, particularly when sitting sideways. This has led to the nickname "Saturday night palsy," as it often happens when someone falls asleep in a chair after drinking alcohol. Other causes include lead poisoning and vitamin B1 deficiency (beriberi). Diseases like diabetes mellitus and leprosy can also damage peripheral nerves, including the radial nerve.

Risk factor

Certain activities increase the risk of developing a drop hand, especially those involving repetitive motions that can injure the radial nerve. Risky activities include prolonged use of crutches or walking aids, hammering, sleeping with the upper arm hanging and the armpit compressed and wearing wristbands, watches, or other objects that press against the wrist.

Symptoms

The primary symptom of a drop hand is the inability to lift the hand or fingers. Other symptoms may include:

• Pain along the outer back of the arm, radiating to the back of the hand and the thumb, index, and middle fingers.
• The pain is often described as burning, stabbing, or aching.
• Numbness or tingling in the same areas.

Drop hand typically affects one side but can occur on both sides if caused by conditions affecting the entire body, such as beriberi or lead poisoning.

Diagnosis

Diagnosing drop hand begins with a thorough medical history, including questions about past injuries, diet, and occupation. A history of gastrointestinal issues could indicate a vitamin B1 deficiency. Falling asleep in a chair a few days prior could provide clues to the cause of drop hand, as could excessive alcohol consumption, which can also lead to vitamin B1 deficiency. Occupational history is relevant if the patient has experienced work-related injuries or worked with paints and pipes, which could indicate lead exposure. Prolonged crutch use may also contribute to dropping hands.

Physical examinations involve direct assessments or using diagnostic tools. Direct examinations might include asking you to lift your hand or perform arm-wrestling-like movements to test hand strength. You might also be asked to move your fingers to determine which nerve is affected. Doctors may also tap your arm to check the triceps reflex in your upper arm.

In addition to direct examinations, several diagnostic tests can be conducted. Electromyography (EMG) measures electrical signals from nerves to muscles and can pinpoint where the radial nerve is compromised. X-rays can detect fractures or abnormal bone growth from the wrist to the shoulder. Magnetic Resonance Imaging (MRI) may reveal nerve compression or damage in nerve branches. Ultrasound (USG) can identify nerve damage due to injury.

Laboratory tests can include blood sugar levels and HbA1c to check glucose control, lead levels, vitamin B12 levels, Antinuclear Antibody (ANA) tests to detect autoimmune diseases, Thyroid-Stimulating Hormone (TSH) and free T4 levels for thyroid function, and Bacillus Calmette-Guérin (BCG) tests if leprosy is suspected.

Management

Managing drop hand typically involves splinting and physical therapy. Splinting is crucial when the condition is due to nerve damage from an injury, as it restricts hand movement to prevent further damage. If there is a fracture, a cast or surgery with fixation devices can be employed to facilitate quicker and more organized healing. Physical therapy is initiated as soon as possible to prevent muscle atrophy and maintain muscle function.

If drop hand is caused by diabetes, managing blood sugar levels with medication, a healthy diet, and regular physical activity can prevent symptoms from worsening. If leprosy is suspected, long-term treatment is necessary, depending on the severity of the disease.

In some cases, surgery may be required. Surgical options include releasing pressure on the nerve, reconnecting severed nerves (re-anastomosis), or tendon transfers to restore hand movement when radial nerve damage is irreversible.

Patients with drop hand are advised to reduce or avoid alcohol and maintain a balanced diet to ensure proper nutrition and avoid excess blood sugar. Pain relievers like ibuprofen can be used to alleviate pain. Here are some tips for daily activities:

• Avoid activities that put excessive pressure on the armpits or shoulders.
• Refrain from repetitive movements that straighten the wrist or rotate the forearm, like hammering.
• Perform doctor-recommended exercises to maintain full range of motion (ROM) in arm and hand joints.
• Avoid wearing wristbands, watches, or other items that could press against the wrist.

Complications

A potential complication of drop hand is permanent damage to the radial nerve, leading to paralysis of the muscles responsible for extending the hand and numbness on the back of the hand. Typically, drop hand caused by injury will fully recover within 2-4 months. However, if there is no symptom improvement within 8-10 weeks, surgery may be considered to relieve nerve pressure.

Prevention

Preventing radial nerve damage generally involves avoiding excessive pressure on the upper arm and armpit. Prevention also includes avoiding repetitive movements that can injure the radial nerve, such as hammering. If your job requires repetitive movements, take frequent breaks and alternate tasks involving different movements. Additionally, ensure that your sitting and sleeping positions do not put pressure on your shoulders, elbows, or wrists.

When to see a doctor?

Seek medical attention immediately if you or someone else sustains an arm injury that could result in a fracture. A broken bone, especially in the upper arm, is a common cause of drop hand. Additionally, consult a doctor if you have difficulty extending or grasping with your hand, as these could be early signs of drop hand. Although drop hand can fully recover, some cases may result in residual symptoms or no recovery. Consulting a doctor can help you choose the best treatment to optimize hand function.

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