Traumatic injuries of the arms (upper limbs) can cause damage and affect the daily functional activities. Nearly 3% of these injuries include fractures of humerus, which commonly and greatly injures the radial nerve. The radial nerve gets injured or damaged due to its anatomical positioning as this nerve is fixed and near the humerus bone.
What is Radial Nerve Injury?
Radial nerve starts from upper arm and runs down the wrist and fingers. It helps in movement and sensation of the arm and hand. This nerve is responsible for extending and controls the ability to bend the wrist and fingers backwards. Radial nerve injury (RNI) is a condition which affects the radial nerve. Radial nerve injury is also known as radial nerve damage or radial nerve trauma.1 Injury results in numbness, weakness and difficulty in moving the wrist, hand or fingers. In severe cases, radial nerve injury may result in radial neuropathy which is also called as radial nerve palsy.
Symptoms of Radial Nerve Injury
Injury to radial nerve exhibits the following symptoms:
- Abnormal Sensations in Hand Due to Radial Nerve Injury: Symptoms of radial nerve injury includes numbness, weakness and at times burning sensation along with pain in the hand.1
- Difficulty in Hand Movements as a Result of Radial Nerve Injury:
- Difficulty straightening the arm at elbow can be a symptom of radial nerve injury
- Difficulty bending the wrist or holding the hand is yet another symptom of radial nerve injury
- Trouble making of the fist
- Trouble turning the arm inward.
- Wrist Drop as a Symptom of Radial Nerve Injury: The wrist (or finger) hangs down and cannot lift things. This deformity occurs in case of severe injury and damage of radial nerve.
- Symptoms of Pinch and Grasp Problems due to Radial Nerve Injury: The thumb and fingers cannot come together to grasp objects.
- Muscle Loss (atrophy) in the Forearm.
Overall injuries to radial nerve can result in significant motor impairment of the arm. Radial nerve injury can affect the entire arm; especially there is loss of functions of wrist such as holding and grasping things leading to a serious handicap.
Prognosis of Radial Nerve Injury
The treatment outcome or prognosis of radial nerve injury mainly depends on the cause and severity of the nerve damage. When the cause is known and successfully treated, a full recovery is possible. Most radial nerve injuries heal within 3 months with first line of treatment. In some cases, complete or partial loss of sensation or movement or nerve pain may exist. In such cases, one should consult the physician to manage the symptoms. These patients can be benefited from physical therapy and occupational therapy.
Causes of Radial Nerve Injury
Radial nerve injury may be caused due to a variety of etiological factors such as physical trauma, pressure and exposure to toxins. Some of them are explained below:
- Radial Nerve Injury Caused Due to Physical Trauma:
- Broken arm bone or fracture
- Falling or receiving blow to the arm
- Improper use of crutches
- Cuts on wrist can damage or separate the radial nerve.
- Intense Pressure Can Cause Radial Nerve Injury:
- Pressure from leaning the arm over back of the chair
- Sleeping with upper arm in an awkward position
- Tightly worn wrist watch can cause radial nerve injury
- Saturday-night palsy (when arm is in a position that pinches the nerve during sleep, especially when the person is intoxicated).
- Unusual growth such as tumor inside wrist may exert pressure against the nerve.
- Radial nerve injury is also caused on overusing the arm, during sport activities and work accidents. This injury also occurs when movements involve both grasping and swinging movements (such as using a hammer). The swinging action of hammer over time causes strain to this nerve.
- Radial Nerve Injury Caused Due to Toxins: Lead poisoning can cause long-term nerve damage including radial nerve damage.
- Health Conditions That Can Cause Radial Nerve Injury: Health conditions such as kidney problems and diabetes may also affect radial nerve.
- Idiopathic Reasons for Radial Nerve Injury: In some cases, there is no known cause. It could also include reasons like asphyxia causing decreased oxygen flow or even blood flow to the area leading to radial nerve injury or damage.
In many of these cases, this condition will improve if the underlying cause is treated.
Complications Due to Radial Nerve Injury
There is possibility of complications in the form of:
- Mild to severe deformity of the hand
- Partial or complete numbness
- Partial or complete loss of hand movement.
When severe radial nerve injury is not attended or not treated immediately, the symptoms of weakness, numbness or pain in arm may become worse. There can be swelling, burning or changes in color of skin of injured arm.
Patient can even lose all movement and sensation in arm accompanied with long term pain. The muscles of hand will begin to tighten and shorten. This may cause hand to curl into a fist and patient may not be able to use it again.
Diagnosis of Radial Nerve Injury
The doctor does physical examination of the affected arm and checks which muscles are affected. Tests are ordered to help figure out the cause of nerve injury.
- X-rays: It helps to diagnose for fractures or other bone injury in the arm causing radial nerve damage.1
- Magnetic Resonance Imaging (MRI): It will examine soft tissues and blood vessels in the arm and check for cysts or masses. It also helps in evaluating entrapment of the radial nerve.
- Electromyography and Nerve Conduction Tests: Electromyography (EMG) and nerve conduction studies measure the electrical activity of the muscles and speed of conduction of impulses along the nerve, respectively. They will check if radial nerve is working at slow pace than normal. These tests also show where the radial nerve is damaged.
- Ultrasound of the elbow to diagnose internal injuries.
- In rare unusual cases, the doctor requests for a nerve biopsy to identify systemic conditions leading to radial nerve injury.
Treatment of Radial Nerve Injury
The aim of treatment for radial nerve injury is to relieve the arm from symptoms and enable patient to use the arm as much as possible. The treatment strategy used is as follows:
- Initial Treatment for Radial Nerve Injury:
- Pain Medicine for Radial Nerve Injury: Analgesic or anti-inflammatory medicines are given to relieve pain and help in fast healing of the injury. In addition, anesthetic creams or patches also help to reduce pain.
- Splint or Cast to Manage Radial Nerve Injury: This is needed to support the wrist and hand when the radial nerve is healing.
- Physical Therapy to Treat Radial Nerve Injury: Special exercises are provided by physical therapists which help to make bones and muscles strong and flexible. Massage therapy is also a good option since it breaks the scar and makes the radial nerve more responsive.
- Transcutaneous Electrical Nerve Stimulation to Treat Radial Nerve Injury: This therapy applies a gentle electric current to patient’s muscles which helps to reduce pain.
- Advanced Treatment for Radial Nerve Injury:
- Surgery to Treat Radial Nerve Injury: This form of therapy is needed to repair radial nerve or to remove if any foreign body such as tumor is pressing on the radial nerve. In case of radial nerve entrapment, surgery is used to relieve pressure on nerve.
- Diabetes and kidney diseases should be treated.
The recovery time depends on the severity of the damage to the radial nerve. In mild cases, there is full recovery, although it may take weeks or months for the nerve to heal. In majority of cases, the patients with radial nerve injury will heal within three months when there is no tear or laceration of radial nerve.
However, in case of severe radial nerve injury such as lacerations, surgery is performed. A complete recovery can take six to eight months. In some cases, it may take up to a year to regain the normal movements and functions of the arm.
While, surprisingly, in some cases, there is no need for treatment and patient with radial nerve injury recovers slowly on their own.
Prevention of Radial Nerve Injury
One should not put pressure on the upper arm and should avoid work functions which lead to repetitive and overuse of arm. Furthermore, one should prevent from being in an awkward sitting and sleeping positions. Care should be taken to avoid falls and breaks which can result in physical trauma and injury to radial nerve.
Radial nerve injury, although painful is treatable. Overall the long term prognosis of radial nerve injury is good when the cause of injury is known. However, in future these patients should take precautions to avoid performing activities which will make them suffer from such injuries to radial nerve again.