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FLEXOR TENDON ANOMALIES IN A PATIENT WITH CARPAL TUNNEL SYNDROME
FLEXOR TENDON ANOMALIES IN A PATIENT WITH CARPAL TUNNEL SYNDROME R. R. SLATER From the Section of Hand and Upper Extremity Surgery, The Permanente Medical Group, Roseville, California, USA
A case of an anomalous interconnection between the tendons of the flexor pollicis longus and the flexor digitorum profundi to both the index and middle fingers at the wrist of a patient presenting with carpal tunnel syndrome is described. The contents of the carpal tunnel should be inspected carefully at the time of median nerve decompression in cases where preoperative clinical examination suggests associated pathologies. Journal of Hand Surgery (British and European Volume, 2001) 26B: 4: 373–376
incision used would have precluded adequate forearm exploration. The patient still had thumb and index finger pain with activity in that hand, although her parasthesiae were diminished. Clinical examination suggested a connection between the flexor pollicis longus and the flexor digitorum profundus of the index finger, but not between the flexor pollicis longus and the flexor digitorum profundus of the middle finger (Fig 2). The patient elected to undergo a left carpal tunnel release, but declined further surgical treatment for her right hand. When the left carpal tunnel was released, marked tenosynovitis was found on its radial side. The distal forearm was explored, revealing two 1.5–2.0 mm diameter anomalous tendon slips. Both originated from the flexor pollicis longus, and one inserted into the flexor digitorum profundus of the index finger, the other into the flexor digitorum profundus of the middle finger (Figs 3, 4). Small muscle bellies were present on each tendon slip, and these blended with the flexor
CASE REPORT A 59-year-old deaf woman who communicated with sign language complained of pain, numbness and tingling in her dominant left hand for 2 years. The parasthesiae were in the distribution of the median nerve and were worse at night. Her pain became worse with rapid motion of her thumb and index and middle fingers during sign language. On physical examination, she had positive Tinel’s, Phalen’s and Durkan’s (Durkan, 1994) signs. Active flexion of the thumb interphalangeal joint was impossible unless the distal interphalangeal joints of the index and middle fingers were also allowed to flex (Fig 1). She experienced pain when flexing her thumb if flexion of the index or middle finger was prevented. Nerve conduction studies confirmed carpal tunnel syndrome. A carpal tunnel release had been performed previously by another surgeon on the patient’s opposite hand, and there was no mention in the operation note of any anomalous tendon slips, but the
Fig 1
Fig 2 The patient’s opposite (right) hand after a previous carpal tunnel release by another surgeon. Physical exam demonstrated a probable connection between the flexor pollicis longus (black arrow highlights active thumb interphalangeal joint flexion) and the flexor digitorum profundus of the index finger (white arrow). The connection had not been excised.
Preoperative physical exam of the patient’s left hand (revealed that) active flexion of the thumb interphalangeal joint (solid arrow) was not possible unless flexion of the distal interphalangeal joints of the index and middle fingers (open arrows) was allowed. 373
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THE JOURNAL OF HAND SURGERY VOL. 26B No. 4 AUGUST 2001
Fig 3 Open carpal tunnel release. Traction on the anomalous tendon slips from the flexor pollicis longus caused flexion of the involved digits, in this case the middle finger (arrow).
Postoperatively, all the symptoms in the patient’s left hand resolved. The hand was still asymptomatic at 2 year follow-up. DISCUSSION
Fig 4 Line drawing of the pathologic anatomy showing the accessory muscle bellies and interconnections between the flexor pollicis longus and flexor digitorum profundus-index and flexor digitorum profundus-middle fingers.
pollicis longus muscle belly proximally (Figs 4, 5). The anomalous tendon slips and muscle bellies were excised.
The flexor pollicis longus in humans is usually independent of the finger flexor digitorum profundus. Phylogenetically, however, the flexor pollicis longus and flexor digitorum profundus are derived from a common mesodermal mass (Kaplan, 1984; Mangini, 1960). Anomalous tendon slips from the flexor pollicis longus tendon or muscle belly were recognized by early anatomists and have been reported in up to 27% of cadavers (Hamitouche et al., 2000; Linburg and Comstock, 1979), but their clinical significance is not often appreciated. Gul and Akbar (1969) reported one case in which there was an anomalous muscle between the flexor pollicis longus and flexor digitorum profundus. Linburg and Comstock (1979) reported four cases of anomalous slips between the flexor pollicis longus and flexor digitorum profundus of the index finger treated operatively. Three of those patients also had signs and symptoms of median nerve compression and had concomitant carpal tunnel releases at the time of surgery. None had a connection between the flexor pollicis longus and the flexor digitorum profundus of the middle finger. Takami et al. (1996) described a case of bilateral flexor pollicis longus/flexor digitorum profundus of the index finger connections blocking independent excursion of the flexor pollicis longus and interfering with
FLEXOR TENDON ABNORMALITIES
375
Fig 5 Anomalous tendon slip and accessory muscle belly shown retracted after distal resection and prior to final excision.
handgun use in a police cadet. Hamitouche et al. (2000) reported finding similar pathology in a young violinist who had distal forearm pain after prolonged musical exercises. Lombardi et al. (1988) reported 33 patients with symptomatic thumb–index finger flexor tenosynovitis. Steroid injections provided no long-term benefit, and 26 wrists in 24 patients were explored surgically. Fifteen wrists had an anomalous tendon slip and all had exuberant tenosynovitis surrounding the flexor pollicis longus and radial finger flexor tendons that restricted independent tendon excursion. At surgery, the tenosynovitis was debrided and the anomalous tendon slips were excised. Carpal tunnel syndrome was usually present, and in 21 wrists a carpal tunnel release was done in addition to the forearm exploration and tendon releases. All of the patients available for follow-up after more than 6 months were improved. The case presented here is the first report of anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus tendons of both the index and middle fingers in a patient diagnosed with carpal tunnel syndrome. It may not be possible to attribute the patient’s carpal tunnel syndrome to the anatomic anomaly alone, but space-occupying lesions do cause the condition (Barnes and Currey, 1967; Vainio, 1957). In this case, the flexor tenosynovitis was present only on the radial side of the carpal tunnel and it is possible that the abnormal tendons caused the tenosynovitis and thus the carpal tunnel syndrome. Resecting the extra tendon slips at the time of the open carpal tunnel release
resulted in complete resolution of the patient’s pain and parasthesiae. In contrast, there was evidence of anomalous tendon slips in the patient’s other hand which was still painful after a carpal tunnel release. Most cases of carpal tunnel syndrome are considered idiopathic, but a specific condition occasionally contributes to, or causes, the median nerve compression. Anatomical deformities and anomalies, including extra tendon slips and flexor tenosynovitis, are among those conditions which should be looked for in patients with carpal tunnel syndrome. Generally, this can be done quickly and easily on physical examination. Some patients with anomalous tendon slips in their wrists might be asymptomatic or only have mild symptoms which do not warrant surgery, but this was not the case in the patient presented here. If anomalous tendon slips are present in a patient with carpal tunnel syndrome refractory to nonoperative treatment, those slips should be resected and any associated tenosynovitis should be debrided at the time of carpal tunnel release.
REFERENCES Barnes CG, Currey HLF (1967). Carpal tunnel syndrome in rheumatoid arthritis. A clinical and electrodiagnostic survey. Annals of Rheumatic Diseases, 26: 226–233. Durkan JA (1994). The carpal-compression test. An instrumented device for diagnosing carpal tunnel syndrome. Orthopaedic Review, 33: 522–525. Gul B, Akbar M (1969). An additional muscle in the deep flexors of the forearm. The Medicus (Karachi), 39: 33–37. Hamitouche K, Roux JL, Baeten Y, Allieu Y (2000). Syndrome de LinburgComstock. E´tude e´pide´miologique et anatomique, application clinique. Chirurgie de la Main, 19: 109–115.
376 Kaplan EB, Riordan DC. The Thumb. In: Spinner M (Ed.) Kaplan’s Functional and Surgical Anatomy of the Hand. Philadelphia, JB Lippincott, 1984: 125. Linburg RM, Comstock BE (1979). Anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus. Journal of Hand Surgery, 4A: 79–83. Lombardi RM, Wood MB, Linscheid RL (1988). Symptomatic restrictive thumb-index flexor tenosynovitis: incidence of musculotendinous anomalies and results of treatment. Journal of Hand Surgery, 13A: 325–328. Mangini U (1960). Flexor pollicis longus muscle: Its morphology and clinical significance. Journal of Bone and Joint Surgery, 42A: 467–470.
THE JOURNAL OF HAND SURGERY VOL. 26B No. 4 AUGUST 2001 Takami H, Takahashi S, Ando M (1996). The Linburg Comstock anomaly: A case report. Journal of Hand Surgery, 21A: 251–252. Vainio K (1957). Carpal canal syndrome caused by tenosynovitis. Acta Rheumatologica Scandinavica, 4: 22–27. Received: 3 October 2000 Accepted after revision: 6 April 2001 Dr Robert R Slater, pt of Orthopaedic Surgery, The Permanente Medical Group, 1600 Eureka Road, Roseville, CA 95661, USA; E-mail: [email protected] # 2001 The British Society for Surgery of the Hand doi: 10.1054/jhsb.2001.0613, available online at http://www.idealibrary.com on
A case of an anomalous interconnection between the tendons of the flexor pollicis longus and the flexor digitorum profundi to both the index and middle fingers at the wrist of a patient presenting with carpal tunnel syndrome is described. The contents of the carpal tunnel should be inspected carefully at the time of median nerve decompression in cases where preoperative clinical examination suggests associated pathologies. Journal of Hand Surgery (British and European Volume, 2001) 26B: 4: 373–376
incision used would have precluded adequate forearm exploration. The patient still had thumb and index finger pain with activity in that hand, although her parasthesiae were diminished. Clinical examination suggested a connection between the flexor pollicis longus and the flexor digitorum profundus of the index finger, but not between the flexor pollicis longus and the flexor digitorum profundus of the middle finger (Fig 2). The patient elected to undergo a left carpal tunnel release, but declined further surgical treatment for her right hand. When the left carpal tunnel was released, marked tenosynovitis was found on its radial side. The distal forearm was explored, revealing two 1.5–2.0 mm diameter anomalous tendon slips. Both originated from the flexor pollicis longus, and one inserted into the flexor digitorum profundus of the index finger, the other into the flexor digitorum profundus of the middle finger (Figs 3, 4). Small muscle bellies were present on each tendon slip, and these blended with the flexor
CASE REPORT A 59-year-old deaf woman who communicated with sign language complained of pain, numbness and tingling in her dominant left hand for 2 years. The parasthesiae were in the distribution of the median nerve and were worse at night. Her pain became worse with rapid motion of her thumb and index and middle fingers during sign language. On physical examination, she had positive Tinel’s, Phalen’s and Durkan’s (Durkan, 1994) signs. Active flexion of the thumb interphalangeal joint was impossible unless the distal interphalangeal joints of the index and middle fingers were also allowed to flex (Fig 1). She experienced pain when flexing her thumb if flexion of the index or middle finger was prevented. Nerve conduction studies confirmed carpal tunnel syndrome. A carpal tunnel release had been performed previously by another surgeon on the patient’s opposite hand, and there was no mention in the operation note of any anomalous tendon slips, but the
Fig 1
Fig 2 The patient’s opposite (right) hand after a previous carpal tunnel release by another surgeon. Physical exam demonstrated a probable connection between the flexor pollicis longus (black arrow highlights active thumb interphalangeal joint flexion) and the flexor digitorum profundus of the index finger (white arrow). The connection had not been excised.
Preoperative physical exam of the patient’s left hand (revealed that) active flexion of the thumb interphalangeal joint (solid arrow) was not possible unless flexion of the distal interphalangeal joints of the index and middle fingers (open arrows) was allowed. 373
374
THE JOURNAL OF HAND SURGERY VOL. 26B No. 4 AUGUST 2001
Fig 3 Open carpal tunnel release. Traction on the anomalous tendon slips from the flexor pollicis longus caused flexion of the involved digits, in this case the middle finger (arrow).
Postoperatively, all the symptoms in the patient’s left hand resolved. The hand was still asymptomatic at 2 year follow-up. DISCUSSION
Fig 4 Line drawing of the pathologic anatomy showing the accessory muscle bellies and interconnections between the flexor pollicis longus and flexor digitorum profundus-index and flexor digitorum profundus-middle fingers.
pollicis longus muscle belly proximally (Figs 4, 5). The anomalous tendon slips and muscle bellies were excised.
The flexor pollicis longus in humans is usually independent of the finger flexor digitorum profundus. Phylogenetically, however, the flexor pollicis longus and flexor digitorum profundus are derived from a common mesodermal mass (Kaplan, 1984; Mangini, 1960). Anomalous tendon slips from the flexor pollicis longus tendon or muscle belly were recognized by early anatomists and have been reported in up to 27% of cadavers (Hamitouche et al., 2000; Linburg and Comstock, 1979), but their clinical significance is not often appreciated. Gul and Akbar (1969) reported one case in which there was an anomalous muscle between the flexor pollicis longus and flexor digitorum profundus. Linburg and Comstock (1979) reported four cases of anomalous slips between the flexor pollicis longus and flexor digitorum profundus of the index finger treated operatively. Three of those patients also had signs and symptoms of median nerve compression and had concomitant carpal tunnel releases at the time of surgery. None had a connection between the flexor pollicis longus and the flexor digitorum profundus of the middle finger. Takami et al. (1996) described a case of bilateral flexor pollicis longus/flexor digitorum profundus of the index finger connections blocking independent excursion of the flexor pollicis longus and interfering with
FLEXOR TENDON ABNORMALITIES
375
Fig 5 Anomalous tendon slip and accessory muscle belly shown retracted after distal resection and prior to final excision.
handgun use in a police cadet. Hamitouche et al. (2000) reported finding similar pathology in a young violinist who had distal forearm pain after prolonged musical exercises. Lombardi et al. (1988) reported 33 patients with symptomatic thumb–index finger flexor tenosynovitis. Steroid injections provided no long-term benefit, and 26 wrists in 24 patients were explored surgically. Fifteen wrists had an anomalous tendon slip and all had exuberant tenosynovitis surrounding the flexor pollicis longus and radial finger flexor tendons that restricted independent tendon excursion. At surgery, the tenosynovitis was debrided and the anomalous tendon slips were excised. Carpal tunnel syndrome was usually present, and in 21 wrists a carpal tunnel release was done in addition to the forearm exploration and tendon releases. All of the patients available for follow-up after more than 6 months were improved. The case presented here is the first report of anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus tendons of both the index and middle fingers in a patient diagnosed with carpal tunnel syndrome. It may not be possible to attribute the patient’s carpal tunnel syndrome to the anatomic anomaly alone, but space-occupying lesions do cause the condition (Barnes and Currey, 1967; Vainio, 1957). In this case, the flexor tenosynovitis was present only on the radial side of the carpal tunnel and it is possible that the abnormal tendons caused the tenosynovitis and thus the carpal tunnel syndrome. Resecting the extra tendon slips at the time of the open carpal tunnel release
resulted in complete resolution of the patient’s pain and parasthesiae. In contrast, there was evidence of anomalous tendon slips in the patient’s other hand which was still painful after a carpal tunnel release. Most cases of carpal tunnel syndrome are considered idiopathic, but a specific condition occasionally contributes to, or causes, the median nerve compression. Anatomical deformities and anomalies, including extra tendon slips and flexor tenosynovitis, are among those conditions which should be looked for in patients with carpal tunnel syndrome. Generally, this can be done quickly and easily on physical examination. Some patients with anomalous tendon slips in their wrists might be asymptomatic or only have mild symptoms which do not warrant surgery, but this was not the case in the patient presented here. If anomalous tendon slips are present in a patient with carpal tunnel syndrome refractory to nonoperative treatment, those slips should be resected and any associated tenosynovitis should be debrided at the time of carpal tunnel release.
REFERENCES Barnes CG, Currey HLF (1967). Carpal tunnel syndrome in rheumatoid arthritis. A clinical and electrodiagnostic survey. Annals of Rheumatic Diseases, 26: 226–233. Durkan JA (1994). The carpal-compression test. An instrumented device for diagnosing carpal tunnel syndrome. Orthopaedic Review, 33: 522–525. Gul B, Akbar M (1969). An additional muscle in the deep flexors of the forearm. The Medicus (Karachi), 39: 33–37. Hamitouche K, Roux JL, Baeten Y, Allieu Y (2000). Syndrome de LinburgComstock. E´tude e´pide´miologique et anatomique, application clinique. Chirurgie de la Main, 19: 109–115.
376 Kaplan EB, Riordan DC. The Thumb. In: Spinner M (Ed.) Kaplan’s Functional and Surgical Anatomy of the Hand. Philadelphia, JB Lippincott, 1984: 125. Linburg RM, Comstock BE (1979). Anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus. Journal of Hand Surgery, 4A: 79–83. Lombardi RM, Wood MB, Linscheid RL (1988). Symptomatic restrictive thumb-index flexor tenosynovitis: incidence of musculotendinous anomalies and results of treatment. Journal of Hand Surgery, 13A: 325–328. Mangini U (1960). Flexor pollicis longus muscle: Its morphology and clinical significance. Journal of Bone and Joint Surgery, 42A: 467–470.
THE JOURNAL OF HAND SURGERY VOL. 26B No. 4 AUGUST 2001 Takami H, Takahashi S, Ando M (1996). The Linburg Comstock anomaly: A case report. Journal of Hand Surgery, 21A: 251–252. Vainio K (1957). Carpal canal syndrome caused by tenosynovitis. Acta Rheumatologica Scandinavica, 4: 22–27. Received: 3 October 2000 Accepted after revision: 6 April 2001 Dr Robert R Slater, pt of Orthopaedic Surgery, The Permanente Medical Group, 1600 Eureka Road, Roseville, CA 95661, USA; E-mail: [email protected] # 2001 The British Society for Surgery of the Hand doi: 10.1054/jhsb.2001.0613, available online at http://www.idealibrary.com on