Cubital Tunnel Syndrome
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Ulnar nerve entrapment is a condition where the
ulnar nerve In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is ...
becomes physically trapped or
pinched ''Pinched'' is a 1917 American short comedy film starring Harold Lloyd. A print of the film is held by the Museum of Modern Art, and it has been released on DVD. Like many American films of the time, ''Pinched'' was subject to cuts by city and ...
, resulting in pain, numbness, or weakness, primarily affecting the little finger and ring finger of the hand. Entrapment may occur at any point from the spine at cervical vertebra C7 to the
wrist In human anatomy, the wrist is variously defined as (1) the Carpal bones, carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; "The wrist contains eight bones, roughly aligned in two rows, known ...
; the most common point of entrapment is in the
elbow The elbow is the region between the arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the media ...
(Cubital tunnel syndrome). Prevention is mostly through correct posture and avoiding repetitive or constant strain (e.g. "cell phone elbow"). Treatment is usually conservative, including medication, activity modification, and exercise, but may sometimes include surgery. Prognosis is generally good, with mild to moderate symptoms often resolving spontaneously.


Signs and symptoms

In general, ulnar
neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or o ...
will result in symptoms in a specific anatomic distribution, affecting the little finger, the ulnar half of the ring finger, and the intrinsic muscles of the hand. The specific symptoms experienced in the characteristic distribution depend on the specific location of ulnar nerve impingement. Symptoms of ulnar neuropathy may be motor, sensory, or both depending on the location of injury. Motor symptoms consistent of muscle weakness; sensory symptoms or paresthesias consist of numbness or tingling in the areas innervated by the ulnar nerve. Proximal impingement is associated with mixed symptoms, as the proximal nerve consists of mixed sensory and motor innervation. Distal impingement is associated with variable symptoms, as the ulnar nerve separates near the hand into distinct motor and sensory branches. In cubital tunnel syndrome (a proximal impingement), sensory and motor symptoms tend to occur in a certain sequence. Initially, there may be numbness of the small and ulnar fourth finger which may be transient. If the impingement is not corrected, the numbness may become constant and progress to hand weakness. A characteristic resting hand position of "ulnar claw," where the small and ring fingers curl up, occurs late in the disease and is a sign of severe neuropathy. By contrast, in Guyon's canal syndrome (distal impingement) motor symptoms and claw hand may be more pronounced, a phenomenon known as the ulnar paradox. Also, the back of the hand will have normal sensation.


Diagnosis

The distinct innervation of the hand usually enables diagnosis of an ulnar nerve impingement by symptoms alone. Ulnar nerve damage that causes paralysis to these muscles will result in a characteristic ulnar claw position of the hand at rest. Clinical tests such as th
card test
for
Froment's sign Froment's sign is a special test of the wrist for palsy of the ulnar nerve, specifically, the action of adductor pollicis. Froment's maneuver can also refer to the cogwheel effect from contralateral arm movements seen in Parkinson's disease. __ ...
, can be easily performed for assessment of ulnar nerve. However, a complete diagnosis should identify the source of the impingement, and radiographic imaging may be necessary to determine or rule-out an underlying cause. Imaging studies, such as
ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
or
MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
, may reveal anatomic abnormalities or masses responsible for the impingement. Additionally, imaging may show secondary signs of nerve damage that further confirm the diagnosis of impingement. Signs of nerve damage include flattening of the nerve, swelling of the nerve proximal to site of injury, abnormal appearance of nerve, or characteristic changes to the muscles innervated by the nerve.


Differential diagnoses

Symptoms of ulnar neuropathy or neuritis do not necessarily indicate an actual physical impingement of the nerve; any injury to the ulnar nerve may result in identical symptoms. In addition, other functional disturbances may result in irritation to the nerve and are not true "impingement". For example, anterior dislocation and "snapping" of ulnar nerve across the medial epicondyle of the elbow joint can result in ulnar neuropathy. Entrapment of other major sensory nerves of the upper extremities result in deficits in other patterns of distribution. Entrapment of the median nerve causes
carpal tunnel syndrome Carpal tunnel syndrome (CTS) is the collection of symptoms and signs associated with median neuropathy at the carpal tunnel. Most CTS is related to idiopathic compression of the median nerve as it travels through the wrist at the carpal tunn ...
, which is characterized by numbness in the thumb, index, middle, and half of the ring finger. Compression of the
radial nerve The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial comp ...
causes numbness of the back of the hand and thumb, and is much rarer. A simple way of differentiating between significant median and ulnar nerve injury is by testing for weakness in flexing and extending certain fingers of the hand. Median nerve injuries are associated with difficulty flexing the index and middle finger when attempting to make a fist. However, with an ulnar nerve lesion, the pinky and ring finger cannot be ''unflexed'' when attempting to extend the fingers. Some people are affected by multiple nerve compressions, which can complicate diagnosis.


Classification

Ulnar nerve entrapment is classified by location of entrapment. The ulnar nerve passes through several small spaces as it courses through the medial side of the upper extremity, and at these points the nerve is vulnerable to compression or entrapment—a so-called "pinched nerve". The nerve is particularly vulnerable to injury when there has been a disruption in the normal anatomy. The most common site of ulnar nerve entrapment is at the elbow, followed by the wrist. Causes or structures which have been reported to cause ulnar nerve entrapment include: * Problems originating at the neck: thoracic outlet syndrome,
cervical spine In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sau ...
pathology, compression by anterior scalene muscles * Problems originating in the chest: compression by
pectoralis minor Pectoralis minor muscle () is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectoralis major in the human body. Structure Attachments Pectoralis minor muscle arises from the upper margins and outer surfaces ...
muscles *
Brachial plexus The brachial plexus is a network () of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve ( C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervicoaxillary canal in th ...
abnormalities *
Elbow The elbow is the region between the arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa (also called the chelidon, or the elbow pit), and the lateral and the media ...
: fractures, growth plate injuries,
cubital tunnel syndrome Ulnar nerve entrapment is a condition where the ulnar nerve becomes physically trapped or pinched, resulting in pain, numbness, or weakness, primarily affecting the little finger and ring finger of the hand. Entrapment may occur at any point from ...
, flexorpronator aponeurosis, arcade of Struthers *
Forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in anat ...
: tight
flexor carpi ulnaris The flexor carpi ulnaris (FCU) is a muscle of the forearm that flexes and adducts at the wrist joint. Structure Origin The flexor carpi ulnaris has two heads; a humeral head and ulnar head. The humeral head originates from the medial epicondyle o ...
muscles *
Wrist In human anatomy, the wrist is variously defined as (1) the Carpal bones, carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; "The wrist contains eight bones, roughly aligned in two rows, known ...
: fractures,
ulnar tunnel syndrome Ulnar tunnel syndrome, also known as Guyon's canal syndrome or Handlebar palsy, is caused by entrapment of the ulnar nerve in the Guyon canal as it passes through the wrist. Symptoms usually begin with a feeling of pins and needles in the ring ...
,
hypothenar hammer syndrome Hypothenar hammer syndrome (HHS) is a vascular occlusion in humans in the region of the ulna. It is caused by repetitive trauma to the hand or wrist (such as that caused by the use of a hammer) by the vulnerable portion of the ulnar artery as it pa ...
* Artery
aneurysms An aneurysm is an outward bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a blood vessel wall. Aneurysms may be a result of a hereditary condition or an acquired disease. Aneurysms can also be a nidus (s ...
or
thrombosis Thrombosis (from Ancient Greek "clotting") is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (thro ...
* ''Other'':
Infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...
s,
tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s,
diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
,
hypothyroidism Hypothyroidism (also called ''underactive thyroid'', ''low thyroid'' or ''hypothyreosis'') is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone. It can cause a number of symptoms, such as po ...
,
rheumatism Rheumatism or rheumatic disorders are conditions causing chronic, often intermittent pain affecting the joints or connective tissue. Rheumatism does not designate any specific disorder, but covers at least 200 different conditions, including art ...
, and
alcoholism Alcoholism is, broadly, any drinking of alcohol (drug), alcohol that results in significant Mental health, mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognize ...


Cubital tunnel syndrome

The most common location of ulnar nerve impingement at the elbow is within the
cubital tunnel The cubital tunnel is a space of the dorsal medial elbow which allows passage of the ulnar nerve around the elbow. It is bordered medially by the medial epicondyle of the humerus, laterally by the olecranon process of the ulna and the tendinous arc ...
, and is known as cubital tunnel syndrome. The tunnel is formed by the
medial epicondyle of the humerus The medial epicondyle of the humerus is an epicondyle of the humerus bone of the upper arm in humans. It is larger and more prominent than the lateral epicondyle and is directed slightly more posteriorly in the anatomical position. In birds, whe ...
, the
olecranon The olecranon (, ), is a large, thick, curved bony eminence of the ulna, a long bone in the forearm that projects behind the elbow. It forms the most pointed portion of the elbow and is opposite to the cubital fossa or elbow pit. The olecranon ...
process of the ulna and the tendinous arch joining the humeral and ulnar heads of the
flexor carpi ulnaris The flexor carpi ulnaris (FCU) is a muscle of the forearm that flexes and adducts at the wrist joint. Structure Origin The flexor carpi ulnaris has two heads; a humeral head and ulnar head. The humeral head originates from the medial epicondyle o ...
muscle. While most cases of injury are minor and resolve spontaneously with time, chronic compression or repetitive trauma may cause more persistent problems. Commonly cited scenarios include: * Sleeping with the arm folded behind neck, elbows bent. * Pressing the elbows upon the arms of a chair while typing. * Resting or bracing the elbow on the arm rest of a vehicle. * Bench pressing. * Intense exercising and strain involving the elbow. Compression of the ulnar nerve at the medial elbow may occasionally be caused by an epitrocheloanconeus muscle, an
anatomical variant An anatomical variation, anatomical variant, or anatomical variability is a presentation of body structure with morphological features different from those that are typically described in the majority of individuals. Anatomical variations are categ ...
.


Ulnar tunnel syndrome

Ulnar nerve impingement along an anatomical space in the wrist called the
ulnar canal The ulnar canal or ulnar tunnel (also known as Guyon's canal or tunnel) is a semi-rigid longitudinal canal in the wrist that allows passage of the ulnar artery and ulnar nerve into the hand. The roof of the canal is made up of the superficial palm ...
is known as
ulnar tunnel syndrome Ulnar tunnel syndrome, also known as Guyon's canal syndrome or Handlebar palsy, is caused by entrapment of the ulnar nerve in the Guyon canal as it passes through the wrist. Symptoms usually begin with a feeling of pins and needles in the ring ...
. Recognized causes of ulnar nerve impingement at this location include local trauma, fractures, ganglion cysts, and classically avid cyclists who experience repetitive trauma against bicycle handlebars. This form of ulnar neuropathy comprises two work-related syndromes: so-called "hypothenar hammer syndrome," seen in workers who repetitively use a hammer, and "occupational neuritis" due to hard, repetitive compression against a desk surface.


Prevention

Cubital tunnel syndrome may be prevented or reduced by maintaining good posture and proper use of the elbow and arms, such as wearing an arm splint while sleeping to maintain the arm is in a straight position instead of keeping the elbow tightly bent. A recent example of this is popularization of the concept of cell phone elbow and game hand.


Treatment

The most effective treatment for cubital tunnel syndrome is surgical decompression. The most safe and effective operation is in-situ decompression +/- medial epicondylectomy. For pain symptoms, medications such as
NSAID Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...
,
amitriptyline Amitriptyline, sold under the brand name Elavil among others, is a tricyclic antidepressant primarily used to treat cyclic vomiting syndrome (CVS), major depressive disorder and a variety of pain syndromes from neuropathic pain to fibromyalgi ...
, or
vitamin B6 Vitamin B6 is one of the B vitamins, and thus an essential nutrient. The term refers to a group of six chemically similar compounds, i.e., "vitamers", which can be interconverted in biological systems. Its active form, pyridoxal 5′-phosphat ...
supplementation may help although there is no evidence to support this claim. Mild symptoms may first be treated non-operatively, with the following: * Elbow joint immobilization in extension at night +/- during the day * Neural flossing/gliding exercises * Strengthening/stretching exercises * Activity modification (e.g. avoidance of pressure on the elbows) It is important to identify positions and activities that aggravate symptoms and to find ways to avoid them. For example, if the person experiences symptoms when holding a telephone up to the head, then the use of a telephone headset will provide immediate symptomatic relief and reduce the likelihood of further damage and inflammation to the nerve. For cubital tunnel syndrome, it is recommended to avoid repetitive elbow flexion and also avoiding prolonged elbow flexion during sleep, as this position puts stress of the ulnar nerve. Cubital tunnel decompression surgery involves an incision posteromedial to the medial epicondyle which helps avoid the medial antebrachial cutaneous nerve branches. The ulnar nerve is identified and released from its fascia proximally and distally up to the flexor carpi ulnaris heads. After release, flexion and extension of the arm are performed to ensure there is no subluxation of the ulnar nerve.


Prognosis

Following surgery, on average, 85% of patients report an improvement in their symptoms Most patients diagnosed with cubital tunnel syndrome have advanced disease (atrophy, static numbness, weakness) that might reflect permanent nerve damage that will not recover after surgery. When diagnosed prior to atrophy, weakness or static numbness, the disease can be arrested with treatment. Mild and intermittent symptoms often resolve spontaneously.


Epidemiology

People with
diabetes mellitus Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...
are at higher risk for any kind of
peripheral neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...
, including ulnar nerve entrapments. Cubital tunnel syndrome is more common in people who spend long periods of time with their elbows bent, such as when holding a telephone to the head. Flexing the elbow while the arm is pressed against a hard surface, such as leaning against the edge of a table, is a significant risk factor. The use of vibrating tools at work or other causes of repetitive activities increase the risk, including throwing a baseball. Damage to or deformity of the elbow joint increases the risk of cubital tunnel syndrome. Additionally, people who have other nerve entrapments elsewhere in the arm and shoulder are at higher risk for ulnar nerve entrapment. There is some evidence that soft tissue compression of the nerve pathway in the shoulder by a bra strap over many years can cause symptoms of ulnar neuropathy, especially in very large-breasted women.


See also

*
Cervical Vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...
*
Ulnar neuropathy Ulnar neuropathy is a disorder involving the ulnar nerve. Ulnar neuropathy may be caused by entrapment of the ulnar nerve with resultant numbness and tingling. It may also cause weakness or and paralysis of the muscles supplied by the nerve. Si ...


References


External links

{{PNS diseases of the nervous system Musculoskeletal disorders Overuse injuries Mononeuropathies of upper limb Syndromes