CARPAL TUNNEL SYNDROME AND FINGER MOVEMENT DYSFUNCTION CAUSED BY TOPHACEOUS GOUT: A CASE REPORT

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1 CARPAL TUNNEL SYNDROME AND FINGER MOVEMENT DYSFUNCTION CAUSED BY TOPHACEOUS GOUT: A CASE REPORT Yu-Chuan Lin, 1,2 Chung-Hwan Chen, 1,2 Yin-Chih Fu, 1,2 Gau-Tyan Lin, 1,2 Je-Ken Chang, 1,2 and Sheang-Tsung Hu 1,2 1 Department of Orthopedics, Kaohsiung Medical University Hospital, and 2 Department of Orthopedics, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. We describe a case of tophaceous gout with a combination of carpal tunnel syndrome and finger movement dysfunction. Carpal tunnel syndrome secondary to gout is uncommon. The concomitant presence of finger movement dysfunction is rare and suggests the involvement of the flexor tendons inside the carpal tunnel. Surgery is recommended to decompress the median nerve, to confirm the diagnosis, and for immediate improvement of flexor tendon excursion. Our patient s finger movement improved dramatically soon after surgery. Key Words: carpal tunnel syndrome, gout, finger movement dysfunction (Kaohsiung J Med Sci 2009;25:34 9) We report a case of tophaceous gout with a combination of carpal tunnel syndrome and finger movement dysfunction. CASE PRESENTATION A 53-year-old farmer with gout had been suffering from multiple joint pain for more than 20 years, but he had not received any treatment for this disease. He visited our outpatient clinic 1 year ago, with a complaint of progressive loss of extension of the long fingers of his left hand. Physical examination Paresthesia was demonstrated along the distribution of the median nerve in the patient s left hand, together 34 Received: Aug 6, 2008 Accepted: Sep 16, 2008 Address correspondence and reprint requests to: Dr Sheang-Tsung Hu, Department of Orthopedics, Kaohsiung Medical University Hospital, 100 Tzyou 1 st Road, Kaohsiung 807, Taiwan. ido_o27@hotmail.com with decreased grip strength and marked atrophy of the thenar muscle. There was loss of active and passive extension of the index, middle, ring, and small fingers of his left hand. Positive Tinel s and Phalen s signs were present. Swelling and local heat were present over the volar aspect of the carpal region. Tumor-like tophi were also observed over the bilateral olecranon regions and feet. Laboratory findings All routine laboratory workups were within normal limits, except for the uric acid level (10.0 mg/100 ml) and erythrocyte sedimentation rate (50.0 mm/hr), which both exceeded the normal ranges. Imaging findings Radiographs of the left hand and wrist showed lesions typical of tophaceous gout. Operative findings Due to a tentative diagnosis of median nerve compression secondary to tophus deposition, surgery was performed to explore the carpal tunnel. After dividing the volar carpal retinaculum, a nodular tophus Kaohsiung J Med Sci January 2009 Vol 25 No Elsevier. All rights reserved.

2 CTS and finger movement dysfunction caused by gout ( cm) was found (Figure 1). The ulnar bursa was markedly swollen because of tenosynovitis. All flexor tendons within the tunnel, except the flexor pollicis longus, were bulky due to infiltration with a chalky white substance, especially the flexor digitorum superficialis tendons of the middle, ring, and small fingers. The median nerve was significantly compressed by the nodular tophus, hypertrophic ulnar bursa and heavily infiltrated tendons. Decompression was achieved by transection of the transverse carpal ligament and removal of the nodular tophus. Tenosynovectomy was performed, and the gouty tophi were excised. The flexor digitorum superficialis tendons of the middle, ring, and small fingers, which were heavily infiltrated, were resected to facilitate deep flexor tendon excursion (Figure 2). The proximal stumps of the flexor digitorum superficialis were sutured with flexor digitorum profundus tendons to preserve grip force. Histopathologic findings The pathologic specimen showed deposition of amorphous urates surrounded by foreign body giant cells and other inflammatory cells (Figure 3). Crystal analysis using polarized light demonstrated negatively birefringent needle-shaped crystals, consistent with sodium urate. Outcome The patient s finger movement improved dramatically soon after the operation. Medications were prescribed to treat his gout. The wound healed without Gouty tophus (2) (1) (3) FCR PL Figure 1. Operative findings 1: a gouty nodular tophus and diffusely infiltrated tophi in the carpal tunnel. FCR = flexor carpi radialis; PL = palmaris longus. Figure 3. Histopathologic findings: tenosynovial tissue with deposition of urate crystals (1), giant cells (2), and inflammatory reaction cells (3). (Hematoxylin & eosin; original magnification 40.) A B Med. N PL Figure 2. Operative findings 2. (A) After removal of tophi and resection of flexor digitorum superficialis tendons of the middle, ring, and small fingers. Med. N = median nerve; PL = palmaris longus. (B) Removed tophi and heavily infiltrated flexor digitorum superficialis tendons. Kaohsiung J Med Sci January 2009 Vol 25 No 1 35

3 Y.C. Lin, C.H. Chen, Y.C. Fu, et al complications. At the 4-month follow-up, there was slight paresthesia over the middle finger, whereas the sensation over the other fingers was normal. The patient was then lost to follow-up. DISCUSSION The carpal tunnel is a rigid cannular path formed by bony walls on three sides and roofed by a tough transverse carpal ligament [1]. Inside the tunnel are the radial bursa with its invested flexor pollicis longus tendon, the ulnar bursa and its invested flexor digitorum superficialis and profundus tendons, and the median nerve with its artery, and a cellulo-adipose layer. The exact pathophysiology of carpal tunnel syndrome is unclear. The median nerve may be directly damaged or secondarily compressed [2]. Secondary compression can be further divided into traumatic and nontraumatic conditions [1]. Gout is one possible cause of nontraumatic compression of the median nerve. Phalen reported 439 cases of carpal tunnel syndrome, only two of which were secondary to gout [2]. Cseuz et al found that seven of 313 cases of carpal tunnel syndrome were caused by gout [3]. Rich et al identified 15 hands (0.6%) with gout in the carpal tunnel from 2,649 carpal tunnel releases [4]. Patil and Chopra found tophaceous gout in three of 316 patients with carpal tunnel syndrome over a 25-year period [5]. We identified a total of 74 cases of carpal tunnel syndrome due to gout in the English literature [2 25] (Table). The reason for so few cases being reported is unclear. Pledger et al mentioned that a large tophaceous deposit is needed to cause median nerve compression, and that this only occurs in patients with severe chronic tophaceous gout [11]. In addition, gout is known to mimic various pathologic conditions, such as tumors, infection and pseudogout, and careful differential diagnosis is required before concluding that secondary compression is due to gout. Several uncommon conditions and underlying diseases, such as rheumatoid arthritis, may also increase the complexity and difficulty of making an accurate diagnosis. Two unusual cases of acute carpal tunnel syndrome caused by tophaceous gout were reported by Ogilvie and Kay [15], and Pai and Tseng [16], respectively. A case with concomitant rheumatoid arthritis has also been reported in the literature [21]. 36 Table. Reported cases of carpal tunnel syndrome caused by gout in the English literature Authors (Year) [Ref.] Cases, n Ward et al (1958) [6] 1 Grossmann et al (1961) [7] 1 Phalen (1966) [2] 2 Cseuz et al (1966) [3] 7 O Hara & Levin (1967) [8] 5 Fujimoto & Seegmiller (1968) [9] 4 Champion (1969) [10] 3 Pledger et al (1976) [11] 1 Green et al (1977) [12] 1 Akizuki & Matsui (1984) [13] 1 Janssen & Rayan (1987) [14] 2 Ogilvie & Kay (1988) [15] 1 Pai & Tseng (1993) [16] 1 Chuang & Wong (1994) [17] 1 Yip et al (1994) [18] 1 Tsai et al (1996) [19] 1 Ali et al (1999) [20] 1 Weinzweig et al (2000) [21] 1 Chen et al (2000) [22] 20 Gonzalez & Cooper (2001) [23] 1 Mockford et al (2003) [24] 1 Tan et al (2003) [25] 1 Rich et al (2004) [4] 13 Patil & Chopra (2007) [5] 3 Total 74 Carpal tunnel syndrome secondary to gout could be a result of an increased volume of contents within the rigid tunnel or a decrease in the internal caliber of the tunnel [1]. An increase in volume could result from synovial hypertrophy due to gouty tenosynovitis, nodular tophi, gouty deposits on the median nerve [14,17], or bulky tendons [4,5,15,16,18,21 25], bursae [5,11,13 15,22,25], and intrinsic muscles [25] caused by tophaceous infiltration. A decrease in caliber could be caused by thickened transverse carpal ligaments [19] resulting from tophaceous infiltration or tophi bulging from the floor of the bony structures of the tunnel [4,5,16,22,24]. In our case, median nerve compression was due to a nodular tophus, tenosynovitis, and tophi infiltrating into the flexor tendons, ulnar bursa and the floor of the carpal tunnel. Tophaceous gout may involve not only the median nerve, but also the flexor tendons inside the carpal tunnel. A few cases of carpal tunnel syndrome secondary to tophaceous gout, along with finger movement dysfunction, such as flexion contracture [5,11,23], stiffness [14] and loss of flexion [21], have previously been reported in the literature. Only Weinzweig et al Kaohsiung J Med Sci January 2009 Vol 25 No 1

4 CTS and finger movement dysfunction caused by gout mentioned that large tophi prevented appreciable excursion of the tendons [21]. In our case, progressive extension failure of the index, middle, ring, and small fingers of the patient s left hand developed due to restricted excursion of the flexor tendons caused by tophi. The condition was dramatically improved after excision of the tophi. Although medical treatment has been reported to be effective for carpal tunnel syndrome secondary to gout [9], surgical decompression is recommended for faster and more reliable relief of symptoms, to confirm the diagnosis, and to avoid permanent damage and potential loss of function [6,11,15 17,24,25]. Release of the transverse carpal ligament alone will not produce satisfactory results if the underlying conditions have not been properly identified and redressed [18]. In our case, surgical exploration was necessary not only to decompress the median nerve by release of the transverse carpal ligament, tenosynovectomy and debulking of the tophi, but to improve excursion by excision of the nodular tophus and gouty deposits that had infiltrated into the flexor tendons. In addition, the heavily infiltrated flexor digitorum superficialis tendons of the middle, ring, and small fingers, which could not be preserved and might hinder tendon excursion, were resected. Mockford et al reported a similar case of a heavily tophaceous infiltrated flexor digitorum superficialis tendon of the right middle finger which had to be sacrificed [24]. They emphasized that every effort should be made to preserve the profundus tendon as its loss will impair hand function. Most reports have shown satisfactory postoperative outcomes with the relief of symptoms and preservation of hand function [6,11,15 17,24,25]. However, some complications can occur, including gouty drainage [14,15] and delayed wound healing with dehiscence [14]. These complications can be avoided by preoperative diagnosis and early use of uricosuric agents [14]. Fortunately, no such problems were encountered in this case. However, the heavily infiltrated flexor digitorum superficialis tendons were sacrificed, which might have influenced hand function. Early diagnosis and control of the patient s gout might have meant that the flexor digitorum superficialis tendons would have been less heavily infiltrated, and could possibly have been preserved. In conclusion, gout is an uncommon cause of carpal tunnel syndrome that should be suspected in patients with a chronic history of gout and carpal tunnel syndrome. The concomitant presence of finger movement dysfunction is rare and suggests the involvement of the flexor tendons inside the carpal tunnel. Surgery is recommended to decompress the median nerve, to confirm the diagnosis, and to immediately improve the excursion of the flexor tendons. Early diagnosis and control of gout are necessary to avoid complications and to preserve hand function. REFERENCES 1. Robbins H. Anatomical study of the median nerve in the carpal tunnel and etiologies of the carpal tunnel syndrome. J Bone Joint Surg Am 1963;45: Phalen GS. The carpal-tunnel syndrome. Seventeen years experience in diagnosis and treatment of six hundred fifty-four hands. J Bone Joint Surg Am 1966; 48: Cseuz KA, Thomas JE, Lambert EH, et al. Long-term results of operation for carpal tunnel syndrome. Mayo Clin Proc 1966;41: Rich JT, Bush DC, Lincoski CJ, et al. Carpal tunnel syndrome due to tophaceous gout. Orthopedics 2004;27: Patil VS, Chopra A. Watch out for pins and needles in hands it may be a case of gout. Clin Rheumatol 2007; 26: Ward LE, Bickel WH, Corbin KB. Median neuritis (carpal tunnel syndrome) caused by gouty tophi. J Am Med Assoc 1958;167: Grossman LA, Kaplan HJ, Ownby FD, et al. Carpal tunnel syndrome initial manifestation of systemic disease. JAMA 1961;176: O Hara LJ, Levin M. Carpal tunnel syndrome and gout. Arch Intern Med 1967;120: Fujimoto WY, Seegmiller JE. Medical treatment of compression neuropathy of median and ulnar nerve in gout. Arthritis Rheum 1968;11: Champion D. Gouty tenosynovitis and the carpal tunnel syndrome. Med J Aust 1969;1: Pledger SR, Hirsch B, Freiberg RA. Bilateral carpal tunnel syndrome secondary to gouty tenosynovitis: a case report. Clin Orthop Relat Res 1976;118: Green EJ, Dilworth JH, Levitin PM. Tophaceous gout. An unusual cause of bilateral carpal tunnel syndrome. JAMA 1977;237: Akizuki S, Matsui T. Entrapment neuropathy caused by tophaceous gout. J Hand Surg [Br] 1984;9: Janssen T, Rayan GM. Gouty tenosynovitis and compression neuropathy of the median nerve. Clin Orthop Relat Res 1987;216: Ogilvie C, Kay NR. Fulminating carpal tunnel syndrome due to gout. J Hand Surg [Br] 1988;13: Pai CH, Tseng CH. Acute carpal tunnel syndrome caused by tophaceous gout. J Hand Surg [Am] 1993;18: Kaohsiung J Med Sci January 2009 Vol 25 No 1 37

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