Injury to the radial nerve, especially with humeral shaft fracture, is of particular incidence in India. Radial nerve palsy damages occur in 7% to 17% of humeral shaft fractures in cadaveric and clinical studies in Indian subjects. Such numbers only emphasise the fact that radial nerve involvement is an ever-present danger with humeral fractures and, at the same time, the overriding necessity of vigilance by the surgeon.

Therefore, if you are preparing for the NEET PG examination, you should familiarise yourself with the radial nerve injury, its causes, symptoms, diagnosis, and treatment. 

Keep reading for a detailed insight into radial nerve injury!

What is Radial Nerve Injury?

The radial nerve passes along the inner side of the arm and is significant in the regulation of motor movement, particularly the triceps muscle, which is positioned at the back part of the upper arm. This muscle allows the ability to extend the elbow, which is necessary to move the arm.

Radial nerve injury may occur due to physical trauma, infections, or exposure to harmful substances such as toxins. Damage to this nerve can result in a condition known as radial neuropathy, more commonly referred to as radial nerve palsy.

Besides the motor control, the radial nerve is also involved in extending the wrist and fingers and participates in the work of sensory activity on the hand. Damage to this nerve can thus lead to weakness or paralysis to straighten the wrist and fingers and even altered sensation in particular areas of the hand.

What are the Causes of Radial Nerve Injury?

When the radial nerve or its protective covering (the myelin sheath) is damaged, the transmission of nerve signals becomes impaired. This disruption can slow down or completely block communication between the brain and the muscles or skin served by the radial nerve, leading to weakness, numbness, or paralysis in the affected areas.

Common causes of radial nerve injury include:

1. Fractures of the Humerus

Fracture of the upper arm bone (humerus), particularly in the mid-shaft, in which the radial nerve travels directly next to the bone, is one of the most common causes of injury to this nerve.

2. Diabetes Mellitus

Persistently elevated sugar in the blood may result in peripheral neuropathy, which mostly relates to major nerves such as the radial nerve, but is much less widely known than nerve damage in other areas caused by diabetes.

3. Improper Use of Crutches

Improper axillary crutch usage may result in excessive pressure applied to the armpit area, which temporarily compresses the radial nerve and gives rise to neuropathy.

4. Tight Accessories Around the Wrist

Pressure on the radial nerve may occur as a result of extended use of a tightly fastened watch or bracelet, which may cut off the nerve because it lies close to the surface of the wrist.

5. Lead Poisoning

Although rare today, exposure to lead can result in a type of neuropathy that may include radial nerve involvement.

6. Prolonged External Pressure

A long-term pressure on the nerve, usually as a result of swelling, inflammation, or a local trauma, can undermine nerve functioning. This can also occur with ill-placed casts or splints.

7. Compression from Arm Positioning During Sleep or Coma

This can happen when one sleeps on their arm in an awkward position (when the radial nerve becomes compressed) or with prolonged unconsciousness (when sleeping in a coma or through intoxication); the result is Saturday night palsy.

8. Idiopathic Cases

In some instances, despite thorough evaluation, no specific cause of the nerve injury can be identified. These are termed idiopathic radial nerve palsies.

What are the Symptoms of Radial Nerve Injury?

It is possible to see that patients with radial nerve damage or compression have various sensory effects and motor effects depending on the location of the damage and the extent of the damage to the nerve. These may comprise:

1. Altered Sensation

• You may experience a tingling, numbness, or burning sensation in the back of the hand, principally the thumb side.
• Disturbances of the senses can also appear in the thumb and fingers.
• Motor weakness and poor coordination.
• Weakness or inability to extend the wrist, which is caused by the wrist drop nerve.
• Weakness in straightening the elbow (mostly in major radial nerve injuries).
• Impaired control in the fingers or hands.

2. Pain or Sensation Loss

• The patients report pain in the forearm.
• There is also likely to be a noticeable reduction in the ability to feel in the place served by the radial nerve.

These clinical presentations tend to be the guideposts of initial diagnosis and may change depending on whether the injury is to the nerve proximally (e.g., in the arm) or more distally (e.g, the posterior branch in the forearm).

What is the Diagnosis of Radial Nerve Injury?

The radial nerve injury test will start with a complete physical and internal history. You will probably be questioned about:

• When and how did your symptoms develop?
• Any new actions, accidents, or reoccurrences that could have provoked the condition?
• Any pre-existing health problems that may cause nerve damage

To diagnose your condition and the level of damage, your physician might prescribe some or all of the following tests:

1. Blood Tests: To eliminate the possibility of systemic nerve damage caused by diabetes or infections.
2. Imaging Studies: Procedures such as ultrasound or MRI scans can be utilised to see the radial nerve and structures around it. This assists in the identification of compression, swelling, and any abnormalities related to trauma.
3. Electromyography (EMG): The test evaluates the electrical activity of muscles using the radial nerve in order to determine the location and extent of the nerve damage.
4. Nerve Conduction Studies: This is used to gauge the speed at which electrical impulses flow along the radial nerve. Faster or slower speeds could be a sign of damage or compression.
5. Nerve Biopsy (Rarely Performed): In rare cases, a small sample of the nerve may be taken and examined under a microscope to identify specific nerve disorders or diseases.

What are the Treatment Options for Radial Nerve Injury?

The primary aim of treatment is to restore maximum function of the affected hand and arm. Management typically focuses on identifying and addressing the underlying cause, if it can be found. In many cases, the condition improves on its own without the need for medical intervention.

Medical Management

In case medicine is needed, you might be advised to take the following:

1. Pain Relief: This could be in the form of over-the-counter painkillers such as paracetamol or ibuprofen, or even strong prescription painkillers.
2. Corticosteroid Injections: This can be administered near the nerve that is affected in order to alleviate pressure and inflammation.

Self-Care and Conservative Therapies

In most cases, your provider will also advise on non-surgical management strategies, such as:

1. Splinting: A splint over the wrist or elbow can help cushion the nerve and alleviate the pain, and stop the problem from getting worse. Based on its severity, the splint could either be permanently worn or worn at night only.
2. Elbow Protection: If the injury is located at the elbow, using an elbow pad and avoiding leaning or bumping the area can help prevent further aggravation.
3. Physiotherapy: Specific exercises can be recommended to keep the muscles in a good state, which does not trigger muscle atrophy of the affected limb.
4. Occupational Therapy: In some cases, therapy or workplace adaptations may be recommended to reduce strain on the nerve during daily activities.

Surgical Intervention

Surgery may be considered if:

1. There is progressive deterioration of symptoms even with the use of conservative treatment.
2. There is clinical or imaging evidence of nerve degeneration or muscle wasting.
3. Surgery may be used in the form of surgical decompression or neurolysis to release pressure on the nerve to aid in functional recovery.

FAQs About Radial Nerve Injury

1. Is radial nerve injury normal?

The radial nerve injury is not termed as normal but is relatively very common, particularly after humerus shaft fractures or compression. Additionally, it is a well-established orthopaedic and neurological clinical condition.

2. How can we prevent radial nerve injury?

Prevention includes avoiding sustained pressure on the upper arm, prevention by accompanying with protective pads in events of possible trauma, and care when conducting the surgical procedures involving the humerus to reduce the occurrence of iatrogenic nerve damage.

3. Can radial nerve injury be treated?

Yes, radial nerve injury can often be treated successfully with rest, splinting, physiotherapy, medications, or surgery, depending on severity. Many cases recover spontaneously over time, especially if the nerve is only compressed, not severed.

Conclusion

The radial nerve injury must be taken into consideration in the event of a patient complaining of wrist drop, failure to extend the fingers, or numbness on the back of the hand. Early detection and intervention remain the most critical parts of preventing long-term impacts and striving to achieve optimal functional recovery.

Chronic symptoms, worsening, or any progression of the symptoms that look like nerve degeneration requires an urgent neurological examination to guide proper treatment and to exclude more severe underlying causes. With expertly curated video lectures, comprehensive revision notes, and high-yield clinical resources, DocTutorials is your trusted partner in mastering complex topics like radial nerve injury.
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