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Carpal and Cubital Tunnel Release
For median and ulnar nerve entrapment

Carpal and Cubital Tunnel Release
(For median and ulnar nerve entrapment)

Carpal tunnel syndrome (CTS) is the most common malady affecting the hand. The basic underlying cause is pressure on the median nerve as it passes through the carpal tunnel at the wrist. Once pain begins, the condition gradually worsens and may result in permanent nerve damage. It is common for CTS to occur in both hands.

Anatomy

  • The carpal tunnel is formed by eight carpal bones in a U-shape on the posterior (back) aspect of the wrist and the transverse carpal ligament (also referred to as the flexor retinaculum) bridging across the carpal bones on the anterior (front) aspect of the wrist (Figure 1)
  • Through the 'tunnel' formed by the bones and ligament pass the tendons that allow the fingers to flex and the median nerve
  • The median nerve is responsible for conducting sensations such as pain from the thumb and first two fingers, and the adjacent palm of the hand. The nerve also controls some muscles that move the thumb

Figure 1 - Anatomy of structures passing through the carpal tunnel including the median nerve and flexor tendons. © T. Graves Figure 2 - Sensory distribution of the median and ulnar nerves. © T. Graves

Pathology

  • The cause of median nerve compression is varied. It effects women more than men and is most common in the fifth and sixth decades of life
  • Some of the specific causes are:
    1. Various diseases such as rheumatoid arthritis, amyloidosis, and hypothyroidism (low thyroid), diabetes mellitus, and alcoholism
    2. Repetitive movements of the wrist such a typing or computer use
    3. Fractures involving the bones of the wrist
    4. Use of air tools
    5. Masses in the carpal tunnel such as a ganglion cyst
    6. Fluid retention as may occur with pregnancy

History and Exam

  • A typical patient with a carpal tunnel syndrome complains of numbness or tingling in the fingers and hands
  • These sensations most typically occur in the thumb and first two fingers and the adjacent palm of the hand (Figure 2)
  • This may be described as pins and needles or heaviness
  • These sensations usually occur at night causing the individual to awaken and shake his hands
  • The pain may also occur with repetitive movements of the hand such as typing or sewing and while driving or using a computer 'mouse'
  • Sometimes the pain may effect the entire hand and even radiate up the arm to the shoulder and thus be confused with a ruptured cervical disk
  • Examination may reveal a wrist deformity or swelling
  • There may be a decrease in sensation over the thumb and first two fingers and at the base of these digits
  • Occasionally there is weakness of the thumb
  • About two-thirds of individuals with CTS will have an electrical sensation in the hand when the doctor taps over the median nerve at the wrist (Tinel's sign)
  • Another test that is more specific for the CTS is reproduction of the symptoms on flexion of the wrist with the forearm held vertically (Phalen's sign)

Tests

  • Sometimes X-rays of the wrist may be of help, especially if there is a history of injury
  • Electomyography (EMG) including nerve conduction velocity studies of the median nerve usually confirm the diagnosis
    1. The most sensitive and earliest abnormality is a prolongation of sensory nerve impulses of the median nerve across the wrist
    2. Later in the disease process, EMG may reveal a loss of nerve function in the thumb muscles innervated by the median nerve

Non-operative Therapy

  • Many cases of CTS are self-limiting
    1. This is especially true of minor cases and those related to a disease that has been successfully treated such as low thyroid treated with thyroid medication
    2. CTS developing during pregnancy frequently disappears after delivery
  • Modifying work habits may decrease or eliminate the pain such as minimizing repetitive hand movements by periodically resting the hands
  • Splints that reduce the amount of wrist flexion and extension. The splints should be used at night as well as during the day for work
  • Medication that reduces swelling and inflammation. Steroid medication (cortisone) may be injected into the carpal tunnel or non-steroidal anti-inflammatory drugs such as Ibuprofen may be given by mouth

The Procedure

  • Surgery is indicated when there is progressive wasting of the muscles in the hand innervated by the median nerve or the pain is unable to be relieved by conservative means
  • When both hands are involved, the most affected hand is usually operated first
  • There are several surgical procedures for releasing or decompressing the carpal tunnel
  • The classical operation is as follows:
    1. An incision is made in the hand and wrist. (Figure 3)
    2. The incision is carried down to the transverse carpal ligament (flexor retinaculum), which is cut throughout its length (Figure 4)
    3. The wound is then sutured
  • Retinaculotomy is a technique that minimizes the incision in the hand
    1. A small incision is made centered over the wrist or in the hand (Animation)
    2. The transverse carpal ligament is opened at the wrist or in the hand following which a special instrument is used to cut the ligament in the hand
    3. This instrument has a blunt foot plate with a sharp blade oriented perpendicular to the foot plate. The foot plate is slipped over the median nerve to protect it as the blade cuts the ligament The instrument may also come with a built in light source
  • Endoscopic carpal tunnel release is similar to retinaculotomy
    1. Two small incisions, one at the wrist and the other in the palm of the hand, are used to insert a tubular instrument called an obturator
    2. The obturator is passed from the incision in the wrist to the incision in the hand
    3. The obturator is then removed leaving a slotted cannula under the ligament
    4. The endoscope is then inserted from the hand towards the wrist along the course of the slotted cannula. The endoscope carries a light source, a fiber optic connection to a television camera and a working port
    5. Under visualization, a hook shaped knife is used to cut the transverse carpal ligament

Figure 3 - Classical incision for exposure of the median nerve in the hand and for release of the carpal tunnel. © T. Graves Figure 4 - Exposure and cutting of the transverse carpal ligament. © T. Graves

Select image below to view animation

Carpal Tunnel Release

Complications

Some of the complications of a carpal tunnel release are:

  • Pain in the hand related to injury to the sensory nerve to the palm
  • Painful scar in the hand
  • Pain as a result of reflex sympathetic dystrophy
  • Blood clot in the wound
  • Wound infection
  • Loss of sensation to the index finger and thumb
  • Weakness of the muscles to the thumb innervated by the median nerve
  • Adhesions between the flexor tendons causing loss of motion
  • Injury to the vessels in the hand
  • Injury to a flexor tendon
  • Injury to the median or ulnar nerve at the wrist
  • Reflex sympathetic dystrophy causing burning pain along with changes in the bone and skin. The skin is initially shiny red and later becomes cool and blue. The cause is unknown

After Surgery

  • After surgery the hand and forearm are usually wrapped in a bandage designed to minimize post-operative bleeding and swelling
  • To reduce swelling, it is best to keep the hand elevated at night on two pillows and in a sling for the first five days
  • After removal of the sutures, the hand may return to normal function
  • The patient should not try to use the hand for heavy lifting or any activity that may strike the hand for 4-6 weeks after surgery
  • Occasionally physical or occupational therapy may be required for range of motion exercises, control of swelling, scar management, progressive strengthening activities and job modification to prevent recurrence

Cubital Tunnel Release
(Release of ulnar nerve entrapment at the elbow)


Cubital tunnel syndrome is also called Ulnar Neuritis. Entrapment of the ulnar nerve is the second most common nerve entrapment after the median nerve in the carpal tunnel and may or may not be due to trauma.

Anatomy

  • The ulnar nerve runs in the upper arm along medial (inside) aspect of the brachial artery. In the middle third of the upper arm the nerve passes through the medial intermuscular septum, a fibrous band between the muscles on the back and front of the upper arm, towards the medial aspect of the elbow
  • The ulnar nerve then passes behind the medial aspect of the elbow into the cubital tunnel (Figure 5)
  • The cubital tunnel starts at the groove in the back of the medial epicondyle of the humerus. The epicondyle is the lower flared out end of the humerus (see Long Bone Fractures)
  • In the cubital tunnel, the ulnar nerve lies on the medial collateral ligaments of the elbow joint and is covered by the arcuate ligament passing from the lower end of the humerus to the ulna
  • On exit from the cubital tunnel the nerve passes into the flexor carpi ulnaris muscle where it gives off some branches and then passes further down the forearm to the hand
  • In the ulnar groove, there is little tissue overlying the ulnar nerve
  • The cubital tunnel is narrowed when the elbow is flexed and distorts the ulnar nerve
  • The ulnar nerve may also be distorted at the intermuscular septum and where it passes into the flexor carpi ulnaris muscle

Figure 5 - Anatomy of the ulnar nerve as seen from behind. © T. Graves

 

Pathology

  • The ulnar nerve may not function properly (ulnar neuropathy) from several causes
  • Because the nerve lies superficial in the cubital tunnel it tends to be vulnerable to injury, which can cause scarring or adhesions about the nerve
  • A common cause is the habit of resting the elbows on a hard surface such as a table or the arm rest of an automobile
  • Neuropathy can also be caused the repetitive flexion and extension of the elbow since each flexion stretches the nerve over the bone
  • The nerve may be injured with a fracture at the elbow
  • Other causes are:
    1. Inflammatory arthritis of the elbow
    2. Various types of tumors in the cubital tunnel (fatty tumors, synovial cysts from the joint lining)
    3. Fibrous bands and abnormal bony or muscle structures compressing the nerve

History and Exam

  • The most prominent symptom is a sharp ache or pain in the elbow that passes down the medial aspect of the forearm towards the ring and little fingers
  • Pain and paresthesias (tingling, numbness) in the distribution noted above occurring when the patient sleeps with the elbow flexed
  • Paresthesias may occur with the elbow flexed and light pressure over the cubital tunnel
  • Tapping over the ulnar nerve in the cubital tunnel may cause an electric shock feeling that travels to the little and ring fingers
  • Numbness and paresthesias may occur in the little and ring fingers
  • There may be a decrease in sensation to touch and pain in the ring and little fingers and adjacent palm of the hand (Figure 2)
  • There may be weakness and atrophy of the small muscles of the hand with weakness of the grip and in spreading the fingers against resistance
  • With severe injury there may be an ulnar claw hand deformity in which the last two fingers are extended at the joint at the base of the fingers and the fingers flexed at the finger joints (Figure 6)

Figure 6 - Claw hand due to injury of the ulnar nerve.

Tests

  • Plain X-ray of the elbow to look for fracture, arthritis, bony spurs or abnormal range of motion at the elbow
  • Electromyography (EMG) of the muscles innervated by ulnar nerve
  • Nerve conduction studies of the ulnar nerve looking for a slowing of nerve impulse conduction across the cubital tunnel

Non-surgical therapy

  • Elbow pads for daily use
  • Elbow splints at night
  • Non-steroidal anti-inflammatory drugs such as ibuprofen
  • Avoidance of repetitive flexion and extension of the elbow, particularly against resistance

Surgical Procedures

  • The procedure is usually carried out as an outpatient in an ambulatory care setting
  • General anesthesia or local anesthesia supplemented with neuroleptic analgesia is used (see Anesthesia)
  • Simple decompression of the ulnar nerve
    1. The incision is about 4 - 5 inches long centered at the elbow. (Figure 7A) The incision may be in back of the elbow over the course of the ulnar nerve or the incision may be curvilinear starting over the intermuscular above the elbow, passing anterior to the elbow and finishing over the flexor carpi ulnaris muscle (Figure 7B)
    2. The ulnar nerve is released by cutting the arcuate ligament (Figure 7C)
    3. The nerve is followed upward and released at the intermuscular septum
    4. The nerve is followed below the elbow into the flexor carpi ulnaris and released from any constricting bands (Figure 7C)
    5. The incision is then closed with sutures
  • Decompression and anterior subcutaneous transposition of the ulnar nerve
    1. The curvilinear incision is used and the nerve released as described above
    2. The nerve is placed in front of the elbow
    3. A tunnel is then formed in the fatty tissue beneath the skin with a few absorbable sutures and the incision closed with sutures (Figure 7D)
  • Medial epicondylectomy
    1. The simple decompression of the nerve is carried out
    2. The medial epicondyle in front of the nerve is removed with a chisel
    3. Soft tissues are sutured over the raw bone surface and the incision closed with sutures

Figure 7a - Incision for release of the ulnar nerve at the elbow. © T. GravesFigure 7b - The ulnar nerve is dissected from the surrounding tissues exposing the ulnar nerve from the medial intermuscular septum to the flexor carpi ulnaris muscle. © T. Graves
Figure 7c - The arcuate ligament is severed to release the ulnar nerve from behind the medial epicondyle of the humerus and transposed to the front of the elbow. © T. GravesFigure 7d - The nerve is held in front of the elbow by creating a subcutaneous (under the skin) tunnel. © T. Graves

Complications

  • Factors predicting a poor result are:
    1. Symptoms existing for over one year before surgery
    2. Severe existing atrophy
    3. Alcoholism
    4. Absence of response to electrical stimulation of the nerve
  • Infection of the wound
  • Hemorrhage into the wound
  • Injury to the blood vessels at the elbow
  • Injury to adjacent muscles
  • Scarring around the nerve
  • Reflex sympathetic dystrophy causing burning pain along with changes in the bone and skin. The skin is initially shiny red and later becomes cool and blue. The cause is unknown
  • Nerve injury with paralysis and/or loss of sensation

Postoperative Care

  • The arm is placed in a sling for a few days following which the arm is mobilized to prevent tethering of the nerve to the surrounding tissues
  • Pain medication is given as needed
  • Sutures are removed in 5 - 7 days after surgery in the surgeon's office