Ulnar Neuropathy (Nerve Damage, Disease and Dysfunction)

Ulnar Neuropathy Definition

Ulnar neuropathy refers to the condition in which one of the nerves in the forearm, known as the ulnar nerve, gets trapped or pinched. Pressure is applied on a nerve resulting in symptoms like pain, tingling, and numbness in parts of the forearm and hand. The term ulnar neuritis is often used interchangeably with ulnar neuropathy. However, neuritis specifically refers to inflammation of the nerve while neuropathy is an umbrella term for all disorders and diseases of the nerve.

Ulnar Neuropathy Location

The ulnar nerve is an important nerve in the arm and is responsible for movement of the forearm. It also provides sensation to the ring and small fingers, a part of the palm, and the hand. The ulnar nerve passes through many ligaments and may get trapped within it or by the bones of the upper extremity. Thickened ligaments  or deformed or distorted bone are more likely to lead to nerve compression.

The ulnar nerve can get trapped at the following points:

  • At or near the elbow region (in the cubital tunnel or the ulnar groove)
  • At or near the wrist (in the Guyon’s canal)
  • In the forearm between the elbow and wrist (above the elbow or below the wrist)

The elbow region is the most common location of ulnar nerve entrapment. If the nerve gets compressed here, it gives rise to painful conditions called tardy ulnar palsy and cubital tunnel syndrome.

Picture from Wikimedia Commons

Ulnar Neuropathy Incidence

In the general population, trapping of the ulnar nerve at the elbow region is very common, second only to nerve entrapment at the wrist (carpal tunnel syndrome). In United States, ulnar neuropathy affects 4 out of 10 people to some degree. People over the age of 35 years are at a greater risk of developing ulnar neuropathy. Men are more likely to be affected than women.

Ulnar Neuropathy Pathophysiology

Neuropathy is a broad term for any damage or disease of a nerve. One of the most common mechanical causes of repeated or persistent neuropathy is compression. Injury to the nerve (trauma) is another leading cause. Depending on the extent of the injury or compression, the nerve may be inflamed and eventually undergo damage particularly to the outer covering of the nerve known as myelin.  Since myelin is important for conduction of signals through the nerve, damage to nerve may result in abnormal signals to the muscles. This can result in muscle weakness. Nerves, like the ulnar nerve, also carry signals back to the brain about sensation in the arm, forearm and hand. Therefore neuropathy may also present as numbness, pain and tingling sensations.

Ulnar Neuropathy Symptoms

Onset and development of the symptoms of ulnar neuropathy may vary among individuals.

Muscle weakness

  • Weakness in the ring and small fingers
  • Inability to make ‘V’ sign with the fingers
  • Loss of grip strength
  • Problems in pinching objects with the thumb and index finger
  • Problems in thumb flexion – moving thumb towards the fingers when hand is upright

Arm Pain

  • Elbow pain
  • Tinel sign at the elbow of the affected hand – severe pain in the ring and small fingers upon tapping over the ulnar nerve at the elbow
  • Stinging sensations in the fingertips of the ring and small fingers

Paresthesia

Paresthesias, which are abnormal sensations, are a major symptom of ulnar neuropathy. Numbness, tingling or burning sensations in the ring and small fingers are typically experienced.

Deformity

In severe and prolonged cases, the hand may have a clawed posture. Here the first knuckle of ring and small fingers drawn towards the hand and second and third knuckles curled towards the palm

If undetected, ulnar neuropathy may result in widespread damage to ulnar nerve. This may lead to loss of function of the ulnar nerve seen as severe muscle weakness or partial paralysis and numbness of the affected area.

Ulnar Neuropathy Causes

Causes of ulnar neuropathy vary depending on the site at which the

Ulnar neuropathy in the elbow region

  • General anesthesia during surgery
  • Blunt trauma
  • Bone deformities that arises with conditions such as rheumatoid arthritis
  • Diseases that ultimately affect the nerves like diabetes mellitus
  • Blocked brachial artery during surgery
  • Contraceptives implanted under the skin
  • Collecting blood from a vein (venipuncture)
  • Pooled blood (hematoma) in hemophilic patients
  • Cigarette smoking
  • Malnutrition
  • Less fat across the elbow and other joints

Ulnar neuropathy in the wrist region

  • Tumors
  • Lumps on joints or tendons of the wrist (ganglionic cysts)
  • Blunt injuries
  • Abnormal artery
  • Unknown reasons

Ulnar Neuropathy Risk Factors

The following risk factors increase the chances of developing ulnar neuropathy :

  • Advancing age
  • Being male
  • Cigarette smoking
  • Being very thin
  • Overuse of forearm and hands
  • Sporting activities
  • Occupational hazards

Ulnar Neuropathy Diagnosis

The signs and symptoms of ulnar neuropathy are indicative of the condition but further investigation is necessary. A neurological examination will help localize the symptoms to the ulnar nerve. This should be followed up with further tests.

Lab tests

Ulnar neuropathy is classified as a type of peripheral neuropathy (resulting from damage to the peripheral nerves). Blood samples are tested in patients with peripheral neuropathies as it can be associated with various other diseases apart from injury and mechanical compression. These lab tests may include a complete blood count (CBC), fasting blood glucose, hemoglobin levels, functions of kidney and thyroid, and presence of HIV and hepatitis  test.

Imaging studies

An ultrasound can be performed to detect the point of compression, tumors, cysts, swelling, and other structural changes around the ulnar nerve. A magnetic resonance imaging (MRI scan) can detect the differences between a normal and a compressed nerve. Other reasons for ulnar neuropathy like osteoarthritis, inflammation of lining of joints (synovitis), or tumors, can also be seen with MRI.

Nerve conduction velocity (NCV) tests

This test measures the speed of the signal across ulnar nerve. For this, electrodes are placed over a muscle of hand and the tendons of ring and small fingers. If ulnar nerve is compressed, damaged or injured in one hand, the speed of signal across the ulnar nerve will be different in affected and unaffected arms.

Electromyography (EMG)

This technique records the electrical activity produced by muscles of hand. A needle-like electrode is put in the muscle tissue through the skin. The electrical activities of muscles at rest and when moving, are recorded. Abnormal activities might indicate ulnar nerve damage.

Biopsy

A small sample of nerve tissue can be collected for microscopic examination. Histological studies can reveal nerve swelling, loss of myelin (demyelination), and inflammation in and around the ulnar nerve. This is not a frequently conducted procedure.

Ulnar Neuropathy Treatment

Treatment aims at removing pressure from the ulnar nerve. Underlying diseases like diabetes mellitus should be treated first and ulnar neuropathy may then resolve, or the symptoms may at the very least ease significantly provided that there is no permanent damage.

Medication

Various pain relievers may be recommended to ease the pain or other uncomfortable sensations. These include :

  • Non-steroidal anti-inflammatory drugs (NSAIDs)
  • Tricyclic anti-depressants (amitriptyline, nortriptyline, desipramine)
  • Anticonvulsants (pregabalin, gabapentin, carbamazepine, lamotrigine, phenytoin).
  • Narcotics (morphine) are prescribed in severe cases.

Physical therapy

Physical therapy aims at relieving pressure on the nerve through manual techniques. It can also help improve grip strength and provide symptomatic relief. A range of different modalities can be used by physical therapists to ease pain. Use of splints and cushions improve the effects of pressure. Occupational therapy and rehabilitation programs are useful in assisting the patient to live and work with the condition.

Surgery

Surgery is recommended to severe cases, with increasing muscle weakness. Surgery is considered only in patients who do not improve with medication and physical therapy.

  • In medial epicondylectomy, the joint end of a bone above epicondyle (bony ridge-like structure) is removed. This allows more room for ulnar nerve.
  • In some patients, flexor carpi ulnaris (FCU) muscle of the forearm is released, which removes pressure from the ulnar nerve.
  • For ulnar neuropathy at the elbow, the nerve may also be moved from behind the medial epicondyle to in front of it. This prevents the nerve from getting caught on the bony ridge and stretching while bending the elbow.
  • Surgery is also performed on patients who have ulnar nerve entrapped in Guyon canal.

References :

http://emedicine.medscape.com/article/1141515-overview

http://www.freemd.com/ulnar-neuritis/overview.htm

http://www.nlm.nih.gov/medlineplus/ency/article/000789.htm

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