Entrapment neuropathy as the name suggests is a medical condition in which the affected nerve gets trapped by direct pressure. This may also refer to nerve root compression such as by a herniated disc in the spine. Typical symptoms include muscle weakness, pain, numbness and tingling. The symptoms affect just one particular part of the body depending upon the nerve that is affected.
Common location for entrapment neuropathy to occur is the joints. The pressure on the nerve can be very painful and can result in damage to the nerve and eventually muscle weakness and wasting if left untreated. Other conditions such as bone spurs, joint swelling, cysts and trauma also can result in nerve entrapment.
Entrapment Neuropathy is also known as Nerve Compression Syndrome or Compression Neuropathy.
Classification and Types of Entrapment Neuropathy or Nerve Compression Syndrome
There are different forms of compression neuropathies depending on the nerve that is affected, but the most common forms are carpal tunnel syndrome and cubital tunnel syndrome, which affect the nerves in the wrist and elbow. When a nerve is compressed, symptoms are often felt away from the actual site of the entrapment. For instance, entrapment neuropathy in the hip or thigh area can result in pain in the legs and feet as the nerves in these areas carry signals to the rest of the leg.
Few of the common forms of Entrapment Neuropathies are mentioned below.
Carpal Tunnel Syndrome: An individual is said to have carpal tunnel syndrome if that individual's median nerve, a major nerve in the upper extremity that travels down the arm and enters the hand through carpal tunnel located in central part of wrist, gets compressed in carpal tunnel causing irritation of the nerve. Typically, this disease affects thumb, index, and middle finger.
Cubital Tunnel Syndrome: An individual is said to have cubital tunnel syndrome if that individual's ulnar nerve, a major nerve in upper extremity gets compressed. Ulnar nerve supplies movement directions to the forearm muscles and sensory information from the hand. In case of cubital nerve syndrome, ulnar nerve gets compressed near the elbow causing wrist and hand weakness, numbness as well as pain. The main fingers involved are little and ring fingers.
Peroneal Neuropathy: Peroneal neuropathy relates to entrapment of the peroneal nerve, most commonly at the knee, however the entrapment can occur at the hip and ankle as well. This commonly leads to weakness of the ankle dorsiflexors and evertors.
Tarsal Tunnel Syndrome: Tarsal tunnel syndrome relates to tibial nerve dysfunction where the tibial nerve gets trapped when it passes through a narrow structure called the tarsal tunnel. This leads to altered sensation in the foot and toes such as numbness, tingling and burning sensation and weakness of the foot muscles.
Handlebar Palsy: This disease is generally experienced by long-distance cyclists. In handlebar palsy, the ulnar nerve in the wrist gets compressed due to long periods of direct pressure on the nerve when the weight of the upper body is resting on the handlebars, thus the term handlebar palsy.
Epidemiology of Entrapment Neuropathy or Nerve Compression Syndrome
Carpal tunnel syndrome is the most common form of entrapment neuropathy. Lifetime risk is approximately 10% and annual risk is 0.1%. Overall prevalence in women is about 3% and in men about 2%. Commonly occurs in females over 55 years.
Cubital tunnel syndrome is the second most common entrapment neuropathy more common in men than in women. Men have less fat content when compared to women in the medial elbow overlying the ulnar coronoid tubercle. The tubercle itself is larger in men. These anatomical factors can be taken as an explanation for higher frequency of ulnar neuropathy or cubital tunnel syndrome in men.
Peroneal neuropathy is the third most common entrapment neuropathy most common type of mononeuropathy in the lower extremities. Next comes the tarsal tunnel syndrome, which again involves the lower extremities.
Pathophysiology of Entrapment Neuropathy or Nerve Compression Syndrome
Repetitive trauma and injury to a nerve may result in microvascular changes, leading to edema and injury to the myelin sheath or the outside layers of the nerve that aid in the transmission of the nerve's messages, and structural alterations in membranes at the organelle levels in both the nerve axon and the myelin sheath. The common feature of compression syndromes is the focal segmental demyelination in the area of compression. Complete recovery of function in less chronic cases after surgical decompression relates to remyelination of the injured nerve. In more chronic cases, entrapment is due to Wallerian degeneration of the axons and permanent fibrotic changes in the neuromuscular junction. This may prevent complete reinnervation and restoration of function.
Causes and Risk Factors of Entrapment Neuropathy or Nerve Compression Syndrome
Compression neuropathies are considered to be the most common forms of nerve injuries. Compression neuropathy can be caused due to various reasons. Compression of the nerve in a small space such as carpal or cubital tunnel is the most common cause. Median nerve getting compressed in the carpal tunnel, posterior tibial nerve compression in the tarsal tunnel, spinal nerve root compression in the intervertebral foramen are few of the examples. Oftentimes the tunnel or space through which the nerve travels is narrowed down by inflammation of the local surrounding tissues or structures, which in turn results in reduced space within the tunnel leading to compression of the nerve.
Other times an injury is caused by an outside mechanical force like for instance radial nerve getting injured in the axillary region due to misfit of crutches. Prolonged pressure from the crutches underneath the axilla results in compression of the radial nerve.
Tension neuropathies are increasingly emerging as important clinical problems though they are not as common as compression neuropathies. It is a known fact that the nervous system must have significant mobility for the body to move properly, especially in the extremities in which the nerves must bend around joints to allow for increase in length as the joints bend at sharp angles. If the mobility is reduced at these joints, it leads to increased tension on nervous tissues which in turn lead to pathological changes.
Signs and Symptoms of Entrapment Neuropathy or Nerve Compression Syndrome
The common signs and symptoms experienced in various types of entrapment neuropathies can be broadly listed as follows:
- Tingling sensation
- Burning sensation
- Muscle weakness
- Muscle wasting
- Impaired movement of affected joints or body part
Chronic Cases Of Entrapment Neuropathy or Nerve Compression Syndrome Can Cause The Following Additional Symptoms:
- Dry skin
- Thinning of the skin
- Thick ridged nails
- Recurrent skin ulcers.
Treatment for Entrapment Neuropathy or Nerve Compression Syndrome
As a rule the underlying medical condition that is the cause of entrapment neuropathy needs to be treated first. There may be instances where the patient may have gained weight. The first treatment for such patients will be to lose the excess weight. If there is no underlying medical condition, then in most of the cases surgery is the next option though there are rare chances that surgery may not relieve all the symptoms in chronic cases.
Nonsurgical Treatments For Entrapment Neuropathy Include The Following:
- Non-steroidal anti-inflammatory drugs or NSAIDs. Anti-inflammatory medicines such as ibuprofen are recommended at the initial onset of symptoms to help reduce the swelling around the nerve.
- Steroid injections like cortisone are very effective anti-inflammatory medicines though steroid injections around the ulnar nerve are generally avoided because of risk of damage to the nerve.
- In case of carpal or cubital tunnel syndrome, bracing or splinting is recommended to wear especially at night to keep the elbow in a straight position.
- Nerve gliding exercises.
- Putting an ice pack on the spine at the site of the pain.
- Physical therapy to reduce tissue swelling and muscle spasms.
- Chiropractic treatment, which falls under alternative medicine.
- Electrotherapy treatments such as transcutaneous electrical nerve stimulators (TENS).
If nonsurgical treatment fails, surgical treatment may be necessary to relieve the pressure off the compressed nerve. Few of the common surgical procedures performed to treat Entrapment Neuropathy are:
- Carpal tunnel release
- Cubital tunnel release
- Ulnar nerve anterior transposition
- Medial epicondylectomy
- Tarsal tunnel release
Diagnosis of Entrapment Neuropathy or Nerve Compression Syndrome
Entrapment neuropathy may be easily diagnosed in cases of external injuries, but diagnosing entrapment neuropathy may be tough at times in case of lack of external injury and the patient may have no clue as to the reason behind the pain. A good physical exam with tests such are Tinel's and Phalen's for hand or other similar tests depending on the part of the body involved help in the diagnosis of entrapment neuropathy.
Following Are The Commonly Used Imaging Tests For Diagnosing Entrapment Neuropathy:
- Magnetic Resonance Imaging (MRI)
- Nerve Conduction Velocity Studies (NCV)