What is Nerve Injury: Types, Treatment, Causes, Symptoms, Risk Factors, Diagnosis
Nerves are composed of tiny cells called neurons that help in connecting the brain and spinal cord to the other parts of the body which further helps in aiding movement, sensations and feelings. The nerves act as a passage that conveys the information from the brain or spinal cord to the other parts of the body in the form of signals and vice versa.
Whenever a nerve gets injured, these signals get interrupted and the information to and from the brain or spinal cord cannot be conveyed. The nerves get damaged when pressure is applied, stretched or cut because of their fragile nature. This damage can result into loss of sensation, feeling or movement in the affected area. Nerves are a critical part of the body which on damage can hamper the normal process of growth and development. Let us see what are the symptoms, causes and treatment of nerve injury.
What is a Nerve Injury?
Nerve injury can be defined as a partial or complete damage of the nerve as a result of strain, stretching, lesion, crushing, shearing or compression. Nerve injury may result in partial to complete loss of the proper functioning of the affected area.
Types of Nerve Injury
Nerve injury can be classified on the basis of pathological change occurring in the nerve. These are: -
- Grade I Nerve Injury/Neuropraxia: It is the least severe of all the types of nerve injury, post which full recovery of the patient can be expected. In this type of nerve injury, the myelin sheath damage prevents the proper signaling of the nerve impulse along the nerve fiber, resulting in temporary functional loss. However, there occurs no loss in nerve continuity. The recovery from grade 1 nerve injury or neuropraxia is possible within 6 to 9 weeks.
- Grade II Nerve Injury/Axonotmesis: This is comparatively a severe type of nerve injury in which the neuronal axon gets disrupted but the outer epineurium stays intact. Grade II nerve injury may result due to the crushing of nerves. Though the nerve injury may undergo a secondary reparative process but it takes time. This type of nerve injury may also cause paralysis.
- Grade III Nerve Injury/Neurotmesis: It is the most serious type of nerve injury, recovery from which is not possible. Grade III nerve injury results in permanent impairing in the functioning of nerve due to serious damage. As a result of nerve injury, not only the continuity of the nerve is disrupted but also the structure of the nerve gets sufficiently damaged. The neurotmesis can further be understood by the Sunderland System of classification of nerve injury.
|Type of Nerve Injury||Consequences|
|First-degree nerve injury||Little disruption in the continuity of nerve but less severe injury with easy recovery|
|Second-degree nerve injury||The continuity of axons is interrupted but can slowly repair and recover|
|Third-degree nerve injury||Severe nerve injury that damages the axon and the surrounding supporting structures; can be repaired with surgical intervention like neurolysis or grafting.|
|Fourth-degree nerve injury||Severe damage to nerve which prevent the regeneration of the nerve, requires nerve grafting to repair the damage|
|Fifth-degree nerve injury||The most severe of all types of nerve injury which may lead to permanent impairment with minimal chances of repair post-surgery|
Symptoms of Nerve Injury
The symptoms that appear due to nerve injury are different depending upon the type of nerve that gets injured. The symptoms based in the type of nerve damaged are:-
- Symptoms of Automatic Nerve Injury: -
- Symptoms of Sensory Nerve Injury:-
- Pricking sensation
- Feeling of continued pain
- Tingling sensation
- Burning sensation
- Symptoms of Motor Nerve Injury: These include
- Muscle atrophy
- Twitching of muscles
- Severe weakness.
Whenever the damage occurs to more than one type of nerves, then the patient may show combination of symptoms.
Causes of Nerve Injury
The various causes behind nerve injuries are:
- Laceration and cuts
- Bruising and contusion due to wounds
- Stretching injury
- Injury caused due to electrical shock
- Compression injuries like crush injuries, strained nerves in the neck, etc.
Risk Factors of Nerve Injury
There are a wide range of risk factors that can cause nerve injury. Some of these risk factors are:
- Autoimmune diseases like multiple sclerosis, lupus, inflammatory diseases, etc can cause nerve injury. Cancer can cause nerve injury either by radiations, nutritional deficiencies or crushing of nerves by the tumor.
- Diabetes commonly affects the sensory neurons and can affect the other types of neurons as well causing diabetic neuropathy.
- Drug side effects from chemotherapy and HIV medication can result in nerve injury
- Toxic substances like mercury, lead and arsenic can damage the nerves.
- Motor neuron diseases that affect the muscles throughout your body leading to progressive deterioration of the nerve.
- Nutritional deficiencies of vitamin B6 and B12 is a risk factor for nerve injury.
- Infectious diseases like Lyme disease, the herpes viruses, HIV, and hepatitis C are also a risk factor for nerve injury.
Complications of Nerve Injury
Severe complications can occur owing to the nerve injuries. Such complications are:
- Development of pain after a critical nerve injury.
- Dysesthesias or abnormal and unpleasant feeling along with burning sensation in the damaged area.
- Paresthesias or Pricking and tingling sensation with burning feeling.
- Painful neural tumors.
- Tenderness, inflammation and pain at the site of injury.
- Presence of causalgia or burning sensation in the limbs.
- Hyperesthesia or severe skin sensitivity.
- Extra sensitivity towards cold.
- Increased sensation of pain during stressful situations.
- Muscle atrophy
- Stiffness in joints.
Diagnosis of Nerve Injury
To completely examine the severity of the nerve injury, various diagnostic tests are conducted. These tests can also be conducted while the actual surgery is being performed when the patient is under sedation. The imaging techniques used for diagnosis are:
- Electromyography (EMG): It is a diagnostic procedure conducted to evaluate if the muscles and the nerves controlling them are healthy or not. This test focuses on motor neurons because these transmit electrical signals which cause contraction in the muscles.
- Nerve Conduction Velocity (NCV): This test is performed to check the quickness of electrical signals that are being transmitted via a specific peripheral nerve.
- Computed Tomography (CT scan): This test utilizes X-rays to produce detailed images of the affected area with the help of computer technology.
- Magnetic Resonance Neurography (MRN): This test uses magnetic and radiofrequencies to create detailed and direct images of the nerves in the body.
Treatment of Nerve Injury
There are various approaches available for the treatment of nerve injury, these approaches can be taken up depending on the severity of the nerve injury:
- Surgical Procedures to Treat Nerve Injury: The surgical measures are opted to restore the normal functioning of the damaged nerve but the type of surgical procedure depends on the type of the nerve injury. In case of discontinuity of the nerve, the nerve fibers are sewn together with an insulated covering to allow the repair of the nerve. When there exists space in between the neurons owing to injury then nerve graft is done by taking a piece of nerve from a part of the body that can donate it. Post-surgery the patient may take three to four weeks to heal.
- Medications to Treat Nerve Injury: In cases when the patient feels a sensation of pain at the site of nerve injury, then medications like pain killers, anti-seizure drugs and Tricyclic antidepressants are prescribed by the doctor.
- Non-Surgical Measures: The various available non-surgical treatments for nerve injury are massage therapy, acupuncture, orthotics, physical therapy and rehabilitation.
Precautions to be Taken While Treating Nerve Injury
The precautionary measures that need to be kept in mind while treating the nerve injury are:
- Monitoring the blood sugar levels for patients suffering from diabetes.
- Preventing nutritional deficiencies in the patient with a wholesome and healthy diet.
- Substituting medications which are responsible in causing nerve damage.
- Opting for therapeutic or surgical measures for patients suffering from trauma due to compression on nerves.
- Administration of prompt treatment for autoimmune disorders.
Nerve Injury can be shocking and traumatizing for the patient. Nerve injury can lead to loss of coherence between the brain and spinal cord with the other parts of the body which may or may not be repaired. The injury to the nerve can cause impairment in movement and sensitivity of the affected area, which can be permanent or temporary depending upon the type of nerve injury and the possibility of restoration after suitable treatments. In most cases, the nerve injury can be repaired with or without surgical intervention; however, some cases may also lead to severe complications like paralysis. Nerve Injury must not be ignored or taken lightly.