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Compression of the lateral antebrachial cutaneous nerve by the biceps tendon
Compression of the lateral antebrachial cutaneous nerve by the biceps tendon Bruce L. Gillingham, MD, and Gregory R. Mack, MD, San Diego, Calif.
Compression of the lateral antebrachial cutaneous nerve (LACN) at the elbow by the lateral edge of the biceps tendon is a rarely recognized entrapment neuropathy. Nineteen cases have been reported to date. 2" 4, ~, 7, ro This study concerns an active duty marine who developed pain and paresthesias in the LACN distribution of his left arm after slam-dunking a basketball. Surgical intervention relieved symptoms refractory to conservative therapy. We present a review of the literature pertaining to the diagnosis, surgical findings, and treatment of this uncommon entity. (J SHOULDER ELBOW SURG 1996;5:330-2.) CASE REPORT A 21-year-old, right-handed marine was medically evacuated from Saudi Arabia for complaints of persistent pain and paresthesias in the volarlateral left forearm extending from the elbow flexion crease to the base of the thumb. The pain and paresthesias were exacerbated by forearm extension in maximal pronation. He denied weakness or numbness of the hand or forearm. The patient's symptoms began soon after slam-dunking a basketball and holding on to the rim and had been present for 10 months at the time of the initial orthopaedic evaluation. In addition, he noted a 2-year history of a grating sensation and left elbow pain while doing push-ups. The latter symptoms developed insidiously with no history of antecedent trauma. Treatment with activity modification and nonsteroidal antiinflammatory medications for a 6-month period did not improve his symptoms. From the Departmentsof Orthopaedics and Clinical Investigation, Naval Medical Center. The Chief, Navy Bureau of Medicine and Surgery, Washington, D.C., Clinical InvestigationProgram sponsored this report #8416 1968-521, as required by HSETCINST 6000.41A. The views expressedin this article are those of the authors and do not reflectthe official policy or position of the Departmentof the Navy, Department of Defense, or the U. S. Government. Reprint requests: LCDR B. L. Gillingham, MC, USN, c/o Clinical Investigation Department, Naval Medical Center, San Diego, CA 92134-5000. 1058-2746/96/$5.00 + 0 3214169051
330
Radiographs revealed an osteocartilaginous loose body in the elbow joint. An olecranon osteotomy was performed. A 1 x 2 cm loose body, which appeared to have originated from the articular surface of the olecranon, was removed. This alleviated his elbow symptoms but did not change those in his forearm. Physical examination 2 months after removal of the loose body revealed a fit, young adult man with no swelling or atrophy of the left arm. Elbow range of motion was normal. Grip strength was equal bilaterally. Two-point discrimination was normal in all digits. Percussion just lateral to the biceps tendon at the elbow flexion crease elicited paresthesias, which radiated to the base of the thumb along the volar-lateral aspect of the left forearm. Sensory examination revealed decreased sensation in the distribution of the LACN. Maximal elbow extension and forearm pronation reproduced the patient's symptoms. Biceps, triceps, and brachioradialis deep-tendon reflexes were equal to the opposite side. Radiographs of the left elbow demonstrated a healed olecranon osteotomy with intact internal fixation and no other significant findings. Electroneuromyography (ENMG) disclosed an absent left lateral antebrachial cutaneous response. The remainder of the ENMG was normal. Surgery was performed to explore the LACN at the elbow. The lateral edge of the biceps tendon was compressing the LACN where it emerged from between the biceps and brachialis muscle bellies (Figure 1). Slight narrowing and focal hyperemia of the LACN beneath the lateral edge of the biceps tendon were present. Elbow extension and forearm pronation accentuated compression of the nerve. To decompress the nerve, an oblique incision was made in the lateral edge of the biceps tendon, creating a triangular flap that was reflected medially and sutured to the remaining tendon (Figure 2). Inspection of the nerve with the elbow extended and the forearm pronated showed no further compression. Pain relief was immediate and complete after surgery. Tinel's sign
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Figure 2 Completedprocedure.Compressionon LACN relieved by reflecting triangular flap of aponeurosis and tendon medially and suturing to remaining tendon. Focal hyperemia and narrowing of LACN was present.
Figure 1 Intraoperativefindings. Focal compression of LACN by biceps aponeurosis is present (arrow). Solid transverse line represents location of relaxing incision. Dashed line representsJinealong which proximal triangular flap was folded.
was absent at the first visit after surgery, and the sensory examination was normal 3 months after surgery. Elbow extension and pronation were no longer provocative. The patient denied weakness. Manual muscle testing of supination and elbow flexion was normal; he remains asymptomatic 4 years later.
DISCUSSION Narasanagi 7 first described compression of the lateral antebrachial cutaneous nerve, the terminal sensory portion of the musculocutaneous nerve, in 1972. Hale 5 reported a case in 1976 of a physician who had carried a camera bag with the strap draped over her antecubital fossa for three.to four days. He labeled the condition "handbag paresthesia. ''5 Felsenthal et al.4 described three cases of LACN compression in which electrodiagnostic studies revealed either a prolonged distal latency
or decrease in the amplitude of the evoked response in the symptomatic arm. Bassett and Nunley2 reported their experience with 11 patients during a 16-year period and found that surgical decompression was effective in seven patients who did not achieve results from conservative treatment. Neuropathy of the LACN at the elbow is characterized by pain over the anterolateral aspect of the elbow, burning dysesthesia of the lateral forearm, and accentuation of symptoms by elbow extension and forearm pronation7 Physical examination may demonstrate tenderness and a positive Tinel's sign just lateral to the biceps tendon and hypesthesia of the anterolateral aspect of the forearm. Other conditions that may have similar symptoms include lateral epicondylitis, cervical radicuIopathy, brachial plexapathy, and median neuropathy in the forearm. A positive Tinel's sign over the LACN and the characteristic sensory loss strongly suggest compression neurapathy; however, ENMG changes may be necessary to confirm the diagnosis. "~ Recommended nonoperative therapy for neuropathy of the LACN includes rest, activity modification, nonsteroidal antiinflammatory medica-
332
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Gillingham and Mack
tions, and splints blocking full extensionT" 4 Massage, whirlpool, active assisted range of motion, and transcutaneous nerve stimulation units have also been used as well as steroid and local anesthetic injections. 4 Surgical decompression appears to be indicated when conservative treatment is unsuccessful. Only four of Bassett and Nunley's patients responded to nonsurgical management, whereas seven who did not respond to 6 to 12 weeks of conservative treatment were relieved of all symptoms and regained normal sensation after surgery7 In Felsenthal's 4 study, the one patient treated surgically remains free of forearm complaints 14 years after surgery. Anatomy texts characteristically depict the LACN emerging at the elbow between the biceps and brachiaJis muscles lateral to the biceps tendon. ~" ~" 8 in 1987, Bourne et al. 3 reported that in their cadaver dissections the nerve emerged from the anterior surface of the brachialis muscle just lateral to the biceps tendon at the level of the interepicondylar line. This study confirmed the work of Olson, 9 who dissected both arms of 64 cadavers in 1969. Our case and prior reports demonstrate that the clinical lesion is focal compression of the LACN by the lateral edge of the biceps aponeurosis and that forearm pronation and elbow extension accentuate nerve compression (Figure 1). Decompression may consist of excision of a triangular wedge of biceps tendon, reflection of a triangular flap of biceps tendon (Figure 2), or simple tenotomy of the lateral 25% of the biceps tendon adjacent to the nerve, s" '~ No late rupture of the biceps tendon has been observed in patients treated with these methods. Other described techniques include freeing the nerve between the brachialis and biceps tendon without cutting the biceps tendon itself or widening the fascia surrounding the nerve as it emerges in the antecubital fossa. 7' lO
Entrapment of the LACN by the lateral edge of the biceps tendon is a rare but clinically distinct syndrome. Patients typically have a history of injury or overuse of the elbow involving extension and maximal pronation of the elbow. Characteristic pain and paresthesia in the volar-lateral forearm exacerbated with elbow extension and forearm pronation are present; ENMG can confirm the diagnosis. If an extensive period of nonoperative therapy is ineffective, persisting symptoms can usually be relieved by surgical decompression. We thank Christine Redfern, BFA, BSc, BMC for artistic assistance. We also thank Richard H. Mack, MD, of Baltimore for clinical follow-up of the surgical case from G. Felsenthal's study and F. H. Bassett III, MD, of Durham for follow-up on his study. REFERENCES
1. AndersonJE. Grant's atlas of anabmy, 7th ed. Baltimore: Williams and Wilkins, 1978. 2. BassettFH III, NunleyJA. Compressionof the musculocuta neous nerveat the dbow. J BoneJoint Surg[Am] 1982;64: 1050-2. 3. Bourne MH, Wood MB, Carmichael SW. Locating the lateral antebrachial cutaneous nerve. J Hand Surg [Am] 1987;12:6979. 4. Felsentha/G,Monddl DL, ReischerMA, Mack RH. Forearm pain secondary to compression syndrome of the lateral cutaneous nerve of the forearm. Arch Phys Med Rehabil 1984;65:139-41. 5. Hale BR. Handbag paraesthesia. Lancet 1976;2:470. 6. Hamilton WJ, ed. Textbookof humananatomy. 2nd ed. St louis: Mosby, 1976:648. 7. Narasanagi SS. Compressionof the lateral cutaneousnerve of forearm. NeurologyIndia 1972;20:224-5. 8. NelterFH. Atlasof humananatomy.SummitNJ: Ciba-Geigy, 1989:406. 9. OJsonIA. Theorigin of the lateralcutaneousnerveof forearm and its anaesthesiafor modified brachial plexusblock.J Anat 19691105:381-2. 10. PatelMR, Bassini L, Magifl R. Compressionneuropathyof the lateral antebracheal cutaneous nerve. Orthopedics 1991; 14:173-4.
Compression of the lateral antebrachial cutaneous nerve (LACN) at the elbow by the lateral edge of the biceps tendon is a rarely recognized entrapment neuropathy. Nineteen cases have been reported to date. 2" 4, ~, 7, ro This study concerns an active duty marine who developed pain and paresthesias in the LACN distribution of his left arm after slam-dunking a basketball. Surgical intervention relieved symptoms refractory to conservative therapy. We present a review of the literature pertaining to the diagnosis, surgical findings, and treatment of this uncommon entity. (J SHOULDER ELBOW SURG 1996;5:330-2.) CASE REPORT A 21-year-old, right-handed marine was medically evacuated from Saudi Arabia for complaints of persistent pain and paresthesias in the volarlateral left forearm extending from the elbow flexion crease to the base of the thumb. The pain and paresthesias were exacerbated by forearm extension in maximal pronation. He denied weakness or numbness of the hand or forearm. The patient's symptoms began soon after slam-dunking a basketball and holding on to the rim and had been present for 10 months at the time of the initial orthopaedic evaluation. In addition, he noted a 2-year history of a grating sensation and left elbow pain while doing push-ups. The latter symptoms developed insidiously with no history of antecedent trauma. Treatment with activity modification and nonsteroidal antiinflammatory medications for a 6-month period did not improve his symptoms. From the Departmentsof Orthopaedics and Clinical Investigation, Naval Medical Center. The Chief, Navy Bureau of Medicine and Surgery, Washington, D.C., Clinical InvestigationProgram sponsored this report #8416 1968-521, as required by HSETCINST 6000.41A. The views expressedin this article are those of the authors and do not reflectthe official policy or position of the Departmentof the Navy, Department of Defense, or the U. S. Government. Reprint requests: LCDR B. L. Gillingham, MC, USN, c/o Clinical Investigation Department, Naval Medical Center, San Diego, CA 92134-5000. 1058-2746/96/$5.00 + 0 3214169051
330
Radiographs revealed an osteocartilaginous loose body in the elbow joint. An olecranon osteotomy was performed. A 1 x 2 cm loose body, which appeared to have originated from the articular surface of the olecranon, was removed. This alleviated his elbow symptoms but did not change those in his forearm. Physical examination 2 months after removal of the loose body revealed a fit, young adult man with no swelling or atrophy of the left arm. Elbow range of motion was normal. Grip strength was equal bilaterally. Two-point discrimination was normal in all digits. Percussion just lateral to the biceps tendon at the elbow flexion crease elicited paresthesias, which radiated to the base of the thumb along the volar-lateral aspect of the left forearm. Sensory examination revealed decreased sensation in the distribution of the LACN. Maximal elbow extension and forearm pronation reproduced the patient's symptoms. Biceps, triceps, and brachioradialis deep-tendon reflexes were equal to the opposite side. Radiographs of the left elbow demonstrated a healed olecranon osteotomy with intact internal fixation and no other significant findings. Electroneuromyography (ENMG) disclosed an absent left lateral antebrachial cutaneous response. The remainder of the ENMG was normal. Surgery was performed to explore the LACN at the elbow. The lateral edge of the biceps tendon was compressing the LACN where it emerged from between the biceps and brachialis muscle bellies (Figure 1). Slight narrowing and focal hyperemia of the LACN beneath the lateral edge of the biceps tendon were present. Elbow extension and forearm pronation accentuated compression of the nerve. To decompress the nerve, an oblique incision was made in the lateral edge of the biceps tendon, creating a triangular flap that was reflected medially and sutured to the remaining tendon (Figure 2). Inspection of the nerve with the elbow extended and the forearm pronated showed no further compression. Pain relief was immediate and complete after surgery. Tinel's sign
J. Shoulder Elbow Surg. Volume 5, Number 4
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331
Figure 2 Completedprocedure.Compressionon LACN relieved by reflecting triangular flap of aponeurosis and tendon medially and suturing to remaining tendon. Focal hyperemia and narrowing of LACN was present.
Figure 1 Intraoperativefindings. Focal compression of LACN by biceps aponeurosis is present (arrow). Solid transverse line represents location of relaxing incision. Dashed line representsJinealong which proximal triangular flap was folded.
was absent at the first visit after surgery, and the sensory examination was normal 3 months after surgery. Elbow extension and pronation were no longer provocative. The patient denied weakness. Manual muscle testing of supination and elbow flexion was normal; he remains asymptomatic 4 years later.
DISCUSSION Narasanagi 7 first described compression of the lateral antebrachial cutaneous nerve, the terminal sensory portion of the musculocutaneous nerve, in 1972. Hale 5 reported a case in 1976 of a physician who had carried a camera bag with the strap draped over her antecubital fossa for three.to four days. He labeled the condition "handbag paresthesia. ''5 Felsenthal et al.4 described three cases of LACN compression in which electrodiagnostic studies revealed either a prolonged distal latency
or decrease in the amplitude of the evoked response in the symptomatic arm. Bassett and Nunley2 reported their experience with 11 patients during a 16-year period and found that surgical decompression was effective in seven patients who did not achieve results from conservative treatment. Neuropathy of the LACN at the elbow is characterized by pain over the anterolateral aspect of the elbow, burning dysesthesia of the lateral forearm, and accentuation of symptoms by elbow extension and forearm pronation7 Physical examination may demonstrate tenderness and a positive Tinel's sign just lateral to the biceps tendon and hypesthesia of the anterolateral aspect of the forearm. Other conditions that may have similar symptoms include lateral epicondylitis, cervical radicuIopathy, brachial plexapathy, and median neuropathy in the forearm. A positive Tinel's sign over the LACN and the characteristic sensory loss strongly suggest compression neurapathy; however, ENMG changes may be necessary to confirm the diagnosis. "~ Recommended nonoperative therapy for neuropathy of the LACN includes rest, activity modification, nonsteroidal antiinflammatory medica-
332
J. Shoulder Elbow Surg. July~August 1996
Gillingham and Mack
tions, and splints blocking full extensionT" 4 Massage, whirlpool, active assisted range of motion, and transcutaneous nerve stimulation units have also been used as well as steroid and local anesthetic injections. 4 Surgical decompression appears to be indicated when conservative treatment is unsuccessful. Only four of Bassett and Nunley's patients responded to nonsurgical management, whereas seven who did not respond to 6 to 12 weeks of conservative treatment were relieved of all symptoms and regained normal sensation after surgery7 In Felsenthal's 4 study, the one patient treated surgically remains free of forearm complaints 14 years after surgery. Anatomy texts characteristically depict the LACN emerging at the elbow between the biceps and brachiaJis muscles lateral to the biceps tendon. ~" ~" 8 in 1987, Bourne et al. 3 reported that in their cadaver dissections the nerve emerged from the anterior surface of the brachialis muscle just lateral to the biceps tendon at the level of the interepicondylar line. This study confirmed the work of Olson, 9 who dissected both arms of 64 cadavers in 1969. Our case and prior reports demonstrate that the clinical lesion is focal compression of the LACN by the lateral edge of the biceps aponeurosis and that forearm pronation and elbow extension accentuate nerve compression (Figure 1). Decompression may consist of excision of a triangular wedge of biceps tendon, reflection of a triangular flap of biceps tendon (Figure 2), or simple tenotomy of the lateral 25% of the biceps tendon adjacent to the nerve, s" '~ No late rupture of the biceps tendon has been observed in patients treated with these methods. Other described techniques include freeing the nerve between the brachialis and biceps tendon without cutting the biceps tendon itself or widening the fascia surrounding the nerve as it emerges in the antecubital fossa. 7' lO
Entrapment of the LACN by the lateral edge of the biceps tendon is a rare but clinically distinct syndrome. Patients typically have a history of injury or overuse of the elbow involving extension and maximal pronation of the elbow. Characteristic pain and paresthesia in the volar-lateral forearm exacerbated with elbow extension and forearm pronation are present; ENMG can confirm the diagnosis. If an extensive period of nonoperative therapy is ineffective, persisting symptoms can usually be relieved by surgical decompression. We thank Christine Redfern, BFA, BSc, BMC for artistic assistance. We also thank Richard H. Mack, MD, of Baltimore for clinical follow-up of the surgical case from G. Felsenthal's study and F. H. Bassett III, MD, of Durham for follow-up on his study. REFERENCES
1. AndersonJE. Grant's atlas of anabmy, 7th ed. Baltimore: Williams and Wilkins, 1978. 2. BassettFH III, NunleyJA. Compressionof the musculocuta neous nerveat the dbow. J BoneJoint Surg[Am] 1982;64: 1050-2. 3. Bourne MH, Wood MB, Carmichael SW. Locating the lateral antebrachial cutaneous nerve. J Hand Surg [Am] 1987;12:6979. 4. Felsentha/G,Monddl DL, ReischerMA, Mack RH. Forearm pain secondary to compression syndrome of the lateral cutaneous nerve of the forearm. Arch Phys Med Rehabil 1984;65:139-41. 5. Hale BR. Handbag paraesthesia. Lancet 1976;2:470. 6. Hamilton WJ, ed. Textbookof humananatomy. 2nd ed. St louis: Mosby, 1976:648. 7. Narasanagi SS. Compressionof the lateral cutaneousnerve of forearm. NeurologyIndia 1972;20:224-5. 8. NelterFH. Atlasof humananatomy.SummitNJ: Ciba-Geigy, 1989:406. 9. OJsonIA. Theorigin of the lateralcutaneousnerveof forearm and its anaesthesiafor modified brachial plexusblock.J Anat 19691105:381-2. 10. PatelMR, Bassini L, Magifl R. Compressionneuropathyof the lateral antebracheal cutaneous nerve. Orthopedics 1991; 14:173-4.