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Lateral antebrachial cutaneous neuropathy
LATERAL ANTEBRACHIAL CUTANEOUS NEUROPATHY DIANE M. ALLEN, MD, and JAMES A. NUNLEY, MD
Lateral antebrachial cutaneous neuropathy is an uncommon, but easily overlooked, cause of elbow pain in the throwing athlete. Compression of the lateral antebrachial cutaneous nerve by the biceps tendon occurs at the nerve's exit point from the brachial fascia just proximal to the elbow flexion crease. Symptoms include pain in the anterolateral elbow and burning dysesthesias radiating into the lateral forearm, particularly when the forearm is fully pronated with the elbow extended. Patients are initially treated conservatively with nonsteroidal antiinflammatory agents, rest, activity modification, and extension block splinting. For those patients who do not respond to nonoperative treatment, surgical decompression of the nerve under local anesthesia provides complete relief of symptoms and return to full activity. KEY WORDS: lateral antebrachial cutaneous nerve, elbow, compression neuropathy
Copyright © 2001 by W.B. Saunders Company
Lateral antebrachial cutaneous neuropathy is an uncommon cause of elbow pain in the throwing athlete; there are only 24 cases reported in the literature to date. Once the possible diagnosis of lateral antebrachial cutaneous neuropathy has been considered in an athlete with anterolateral elbow pain, however, the condition is relatively straightforward to diagnose and successfully treat. The lateral antebrachial cutaneous nerve is the distal extension of the musculocutaneous nerve, which provides sensory innervation to the radial, proximal one half of the forearm. It travels in the anterior compartment of the arm between the biceps and brachialis, piercing the brachial fascia lateral to the biceps tendon at or near the elbow flexion crease, assuming a subcutaneous position. 1 When the elbow is in a position of full extension and the forearm in pronation, such as the follow-through phase of throwing, the lateral border of the biceps tendon may compress the nerve where it is tethered at its exit point through the brachial fascia. Athletes with compression of the lateral antebrachial cutaneous nerve report pain about the elbow and burning dysesthesias radiating into the radial forearm, particularly with forcible pronation in full extension. Typical inciting activities include vigorous backstroke swimming, a forceful overhead tennis stroke with the forearm pronated, and a backhand stroke in racquetball with the elbow extended. 2-4 Acute traumatic onset of symptoms has also been reported after dunking a basketball and hanging on
From the Duke University Medical Center, Durham, NC.
Address reprint requests to James A. Nunley, MD, Division of Orthopaedic Surgery, Duke University Medical Center, Box 2923 DUMC, Durham, NC 27710. Copyright © 2001 by W.B. Saunders Company 1060-1872/01/0904-0006535.00/0 doi:10.1053/otsm.2001.25575
222
the rim? The patient's symptoms may be acute or chronic at the time of presentation; roughly one half of patients recall a traumatic onset of their symptoms. Physical examination of a patient with compression of the lateral antebrachial cutaneous nerve reveals reproduction of symptoms by bringing the forearm into full pronation and extension. There is tenderness lateral to the biceps tendon and usually a positive Tinel's sign at the same point. Most patients have objective numbness of the lateral forearm. There is no motor deficit because the lateral antebrachial cutaneous nerve is a purely sensory. The presence of biceps weakness should alert the examiner to the possibility of musculocutaneous nerve injury or cervical radiculopathy. 6 The range of motion is usually within normal limits, although there may be some loss of terminal extension, especially with the forearm pronated. Electrodiagnostic studies have documented either a prolonged distal latency or decreased amplitude of the evoked response of the lateral antebrachial cutaneous nerve in the symptomatic arm of affected patients4; however, we have not found it routinely necessary to use these tests for confirmation of the diagnosis. Differential diagnosis may include lateral epicondylitis, cervical radiculopathy, radial tunnel and pronator teres syndromes, and biceps tendonitis. It has been our experience that these conditions can be differentiated from compression neuropathy of the lateral antebrachial cutaneous nerve on the basis of the history and physical examination. 3 Athletes may initially be treated conservatively with rest, ice, nonsteroidal anti-inflammatory medications, activity modification, and extension block splinting. For patients whose symptoms are refractory to these methods, we employ local steroid injection just lateral to the biceps tendon at the exit point of the lateral cutaneous nerve of the forearm, followed by splinting in flexion and supination for 7 to 10 days. Other investigators have reported success with ultrasound and transcutaneous electrical
Operative Techniques in Sports Medicine, Vol 9, No 4 (October), 2001 : pp 222-224
nerve stimulation (TENS). 4 In our report of 19 patients treated between 1965 and 1992, only 4 had successful management of their symptoms without operative intervention. For those patients in w h o m nonoperative treatment fails to relieve symptoms after 6 to 12 weeks, we have found a simple surgical release under local anesthesia to be uniformly successful.
SURGICAL TECHNIQUE The patient is positioned supine on the operating table with the entire extremity sterilely prepped and draped free on the hand table. A curvilinear incision is marked over the antecubital fossa. The superficial skin is then injected with local anesthetic and epinephrine, unless the patient prefers regional or general anesthesia. Care is taken not to anesthetize the lateral antebrachial cutaneous nerve, so that adequate intraoperative decompression can be confirmed. The nerve is then identified in the w o u n d 1 fingerbreadth lateral to the biceps tendon and traced proximally to the point where it exits from the biceps aponeurosis. If the elbow is then placed in full extension and pronafion, the lateral margin of the biceps tendon can be observed to compress the lateral antebrachial cutaneous nerve where it is tethered by the deep fascia (Fig 1).
Fig 2. The completed procedure shows the tendon flap may be sutured to the medial portion of the biceps tendon or excised. The elbow is taken through a full range of motion to confirm relief of compression in all positions, (Reprinted with permission, s)
Patients under local anesthesia will report pain with this maneuver if the nerve has not been anesthetized. Additional local anesthetic is then injected into the bicipital aponeurosis and tendon, and a triangular wedge of tendon overlying the nerve is excised or sutured back as a reflected flap (Fig 2). The nerve can then be seen lying on the brachial fascia where it is typically flattened and constricted. The elbow is then taken through a full range of motion to confirm that the biceps tendon does not compress the nerve in any position and that the patient is symptom free. The w o u n d is closed with a nonabsorbable interrupted suture, and the elbow is splinted in 90 ° of flexion in neutral rotation. The patient is removed from the splint the first or second day after surgery and returned to full activities at 2 to 3 weeks.
RESULTS
Fig 1. Focal compression of the lateral antebrachial cutaneous nerve by the biceps aponeurosis is seen at operation. The solid and dashed lines represent the portion of the tendon that is excised or sutured back as a reflected flap. (Reprinted with permission. 5)
LATERAL ANTEBRACHIAL CUTANEOUS NEUROPATHY
All patients in our report achieved immediate relief of pain and full range of motion after the procedure. 3 The return of normal sensibility occurred within a month of surgery, and all patients returned to full activity. One patient treated nonoperatively remained slightly numb in the volar radial aspect of the forearm, but this was not deemed severe enough to warrant surgical intervention. 2 Another patient did require release of her extensor mass for persistent symptoms of lateral epicondylitis 2 years after surgical intervention; however, the index procedure did relieve her presenting symptom of burning pain radiating into her forearm. 2 There were no complications in this small group of patients.
223
REFERENCES 1. Olson IA: The origin of the lateral cutaneous nerve of the forearm and its anesthesia for modified brachial plexus block. J Anat 105:381-382, 1969 2. Bassett FH, Nunley JA: Compression of the musculocutaneous nerve at the elbow. J Bone Joint Surg Am 64:1050-1052, 1982 3. Davidson JJ, Bassett FH, Nunley JA: Musculocutaneous nerve entrapment revisited. J Shoulder Elbow Surg 7:250-254, 1998
224
4. Felsenthal G, Mondell DL, Reischer MA, et al: Forearm pain secondary to compression syndrome of the lateral cutaneous nerve of the forearm. Arch Phys Med Rehabil 65:139-141, 1984 5. Gillingham BL, Mack GR: Compression of the lateral antebrachial cutaneous nerve by the biceps tendon. J Shoulder Elbow Surg 5:330332, 1996 6. Braddom RL, Wolfe C: Musculocutaneous nerve injury after heavy exercise. Arch Phys Med Rehabil 59:290-293, 1978
ALLEN AND NUNLEY
Lateral antebrachial cutaneous neuropathy is an uncommon, but easily overlooked, cause of elbow pain in the throwing athlete. Compression of the lateral antebrachial cutaneous nerve by the biceps tendon occurs at the nerve's exit point from the brachial fascia just proximal to the elbow flexion crease. Symptoms include pain in the anterolateral elbow and burning dysesthesias radiating into the lateral forearm, particularly when the forearm is fully pronated with the elbow extended. Patients are initially treated conservatively with nonsteroidal antiinflammatory agents, rest, activity modification, and extension block splinting. For those patients who do not respond to nonoperative treatment, surgical decompression of the nerve under local anesthesia provides complete relief of symptoms and return to full activity. KEY WORDS: lateral antebrachial cutaneous nerve, elbow, compression neuropathy
Copyright © 2001 by W.B. Saunders Company
Lateral antebrachial cutaneous neuropathy is an uncommon cause of elbow pain in the throwing athlete; there are only 24 cases reported in the literature to date. Once the possible diagnosis of lateral antebrachial cutaneous neuropathy has been considered in an athlete with anterolateral elbow pain, however, the condition is relatively straightforward to diagnose and successfully treat. The lateral antebrachial cutaneous nerve is the distal extension of the musculocutaneous nerve, which provides sensory innervation to the radial, proximal one half of the forearm. It travels in the anterior compartment of the arm between the biceps and brachialis, piercing the brachial fascia lateral to the biceps tendon at or near the elbow flexion crease, assuming a subcutaneous position. 1 When the elbow is in a position of full extension and the forearm in pronation, such as the follow-through phase of throwing, the lateral border of the biceps tendon may compress the nerve where it is tethered at its exit point through the brachial fascia. Athletes with compression of the lateral antebrachial cutaneous nerve report pain about the elbow and burning dysesthesias radiating into the radial forearm, particularly with forcible pronation in full extension. Typical inciting activities include vigorous backstroke swimming, a forceful overhead tennis stroke with the forearm pronated, and a backhand stroke in racquetball with the elbow extended. 2-4 Acute traumatic onset of symptoms has also been reported after dunking a basketball and hanging on
From the Duke University Medical Center, Durham, NC.
Address reprint requests to James A. Nunley, MD, Division of Orthopaedic Surgery, Duke University Medical Center, Box 2923 DUMC, Durham, NC 27710. Copyright © 2001 by W.B. Saunders Company 1060-1872/01/0904-0006535.00/0 doi:10.1053/otsm.2001.25575
222
the rim? The patient's symptoms may be acute or chronic at the time of presentation; roughly one half of patients recall a traumatic onset of their symptoms. Physical examination of a patient with compression of the lateral antebrachial cutaneous nerve reveals reproduction of symptoms by bringing the forearm into full pronation and extension. There is tenderness lateral to the biceps tendon and usually a positive Tinel's sign at the same point. Most patients have objective numbness of the lateral forearm. There is no motor deficit because the lateral antebrachial cutaneous nerve is a purely sensory. The presence of biceps weakness should alert the examiner to the possibility of musculocutaneous nerve injury or cervical radiculopathy. 6 The range of motion is usually within normal limits, although there may be some loss of terminal extension, especially with the forearm pronated. Electrodiagnostic studies have documented either a prolonged distal latency or decreased amplitude of the evoked response of the lateral antebrachial cutaneous nerve in the symptomatic arm of affected patients4; however, we have not found it routinely necessary to use these tests for confirmation of the diagnosis. Differential diagnosis may include lateral epicondylitis, cervical radiculopathy, radial tunnel and pronator teres syndromes, and biceps tendonitis. It has been our experience that these conditions can be differentiated from compression neuropathy of the lateral antebrachial cutaneous nerve on the basis of the history and physical examination. 3 Athletes may initially be treated conservatively with rest, ice, nonsteroidal anti-inflammatory medications, activity modification, and extension block splinting. For patients whose symptoms are refractory to these methods, we employ local steroid injection just lateral to the biceps tendon at the exit point of the lateral cutaneous nerve of the forearm, followed by splinting in flexion and supination for 7 to 10 days. Other investigators have reported success with ultrasound and transcutaneous electrical
Operative Techniques in Sports Medicine, Vol 9, No 4 (October), 2001 : pp 222-224
nerve stimulation (TENS). 4 In our report of 19 patients treated between 1965 and 1992, only 4 had successful management of their symptoms without operative intervention. For those patients in w h o m nonoperative treatment fails to relieve symptoms after 6 to 12 weeks, we have found a simple surgical release under local anesthesia to be uniformly successful.
SURGICAL TECHNIQUE The patient is positioned supine on the operating table with the entire extremity sterilely prepped and draped free on the hand table. A curvilinear incision is marked over the antecubital fossa. The superficial skin is then injected with local anesthetic and epinephrine, unless the patient prefers regional or general anesthesia. Care is taken not to anesthetize the lateral antebrachial cutaneous nerve, so that adequate intraoperative decompression can be confirmed. The nerve is then identified in the w o u n d 1 fingerbreadth lateral to the biceps tendon and traced proximally to the point where it exits from the biceps aponeurosis. If the elbow is then placed in full extension and pronafion, the lateral margin of the biceps tendon can be observed to compress the lateral antebrachial cutaneous nerve where it is tethered by the deep fascia (Fig 1).
Fig 2. The completed procedure shows the tendon flap may be sutured to the medial portion of the biceps tendon or excised. The elbow is taken through a full range of motion to confirm relief of compression in all positions, (Reprinted with permission, s)
Patients under local anesthesia will report pain with this maneuver if the nerve has not been anesthetized. Additional local anesthetic is then injected into the bicipital aponeurosis and tendon, and a triangular wedge of tendon overlying the nerve is excised or sutured back as a reflected flap (Fig 2). The nerve can then be seen lying on the brachial fascia where it is typically flattened and constricted. The elbow is then taken through a full range of motion to confirm that the biceps tendon does not compress the nerve in any position and that the patient is symptom free. The w o u n d is closed with a nonabsorbable interrupted suture, and the elbow is splinted in 90 ° of flexion in neutral rotation. The patient is removed from the splint the first or second day after surgery and returned to full activities at 2 to 3 weeks.
RESULTS
Fig 1. Focal compression of the lateral antebrachial cutaneous nerve by the biceps aponeurosis is seen at operation. The solid and dashed lines represent the portion of the tendon that is excised or sutured back as a reflected flap. (Reprinted with permission. 5)
LATERAL ANTEBRACHIAL CUTANEOUS NEUROPATHY
All patients in our report achieved immediate relief of pain and full range of motion after the procedure. 3 The return of normal sensibility occurred within a month of surgery, and all patients returned to full activity. One patient treated nonoperatively remained slightly numb in the volar radial aspect of the forearm, but this was not deemed severe enough to warrant surgical intervention. 2 Another patient did require release of her extensor mass for persistent symptoms of lateral epicondylitis 2 years after surgical intervention; however, the index procedure did relieve her presenting symptom of burning pain radiating into her forearm. 2 There were no complications in this small group of patients.
223
REFERENCES 1. Olson IA: The origin of the lateral cutaneous nerve of the forearm and its anesthesia for modified brachial plexus block. J Anat 105:381-382, 1969 2. Bassett FH, Nunley JA: Compression of the musculocutaneous nerve at the elbow. J Bone Joint Surg Am 64:1050-1052, 1982 3. Davidson JJ, Bassett FH, Nunley JA: Musculocutaneous nerve entrapment revisited. J Shoulder Elbow Surg 7:250-254, 1998
224
4. Felsenthal G, Mondell DL, Reischer MA, et al: Forearm pain secondary to compression syndrome of the lateral cutaneous nerve of the forearm. Arch Phys Med Rehabil 65:139-141, 1984 5. Gillingham BL, Mack GR: Compression of the lateral antebrachial cutaneous nerve by the biceps tendon. J Shoulder Elbow Surg 5:330332, 1996 6. Braddom RL, Wolfe C: Musculocutaneous nerve injury after heavy exercise. Arch Phys Med Rehabil 59:290-293, 1978
ALLEN AND NUNLEY