Hand purulent tenosynovitis with carpal tunnel syndrome

Purulent flexor tenosynovitis, also known as pyogenic or suppurative flexor tenosynovitis, is an aggressive closed-space infection of the upper extremity’s digital flexor tendon sheath, causing severe disability if not treated immediately and appropriately. An extensive proximal spread of bacteria can cause infection of the Parona space, the quadrilateral potential space at the wrist bordered by the pronator quadratus, digital flexors, flexor pollicis longus, and flexor carpi ulnaris. This inflammation can potentially result in acute median nerve compression and acute carpal tunnel syndrome.[1] Its prevalence ranges from 2.5% to 9.4%.[2] It is highly frequent in patients with a recent history of penetrating trauma, but cases of hematogenous bacterial seeding have also been documented.[3] Infectious flexor tenosynovitis is primarily diagnosed by a physical examination showing four cardinal characteristics, known as Kanavel’s sign. This sign consists of symmetrical/fusiform swelling of the affected fingers, the affected fingers being held in a flexed position, pain on any attempt of passive finger extension, and tenderness along the course of the flexor tendon sheath.[4] It is primarily treated by surgical drainage. However, cases of untreated disease and late diagnosis or presentation can lead to significant damage to hand function, forcing more drastic countermeasures, such as amputation, in an immunocompromised patient.[5] Here, we present a case of purulent tenosynovitis and its treatment and outcome. A 62-year-old female was presented to our emergency department with 4 days of right-hand pain and swelling. She has a history of invasive ductal carcinoma of the left breast status post-left partial mastectomy and underwent adjuvant chemotherapy, complete radiotherapy, and endocrine therapy previously. A penetrating injury, insect bite, or hand sprain was not reported. She did not experience any fever or chills in the past few days. She complained that her right hand was swollen and warmer than the left hand, but denied having any open wounds or skin lesions. Physical examination revealed right-hand swelling and tenderness extending to the right wrist and thenar eminence with flexion and extension limitations. She also felt pain with passive finger extension and tenderness to palpation along the flexor tendon. Her right hand had poor blood circulation, with pale fingertips and numbness. Phalen’s test and Tinel’s sign were positive on the right hand. Additionally, all five fingers and the thenar area showed sensory impairment. Her right hand could grasp, but the muscle strength was significantly weaker than her left hand. Her fingers were held in a flexed position [Figure 1]. The forearm was soft, with no tenderness in that area. Ascending lymphangitis was also not evident.Figure 1: Right-hand swelling and tenderness extending to the right wrist without obvious wounds, fusiform swelling of fingers held in a flexed position (Kanavel’s signs)Regarding laboratory results, C-reactive protein (12.88 mg/dL) and white blood cell count (13,900/μL) increased. In the contrast-enhanced computed tomography (CT) of the right hand and wrist, digital flexor tendons were inflamed, with increased infiltration and fat stranding in the soft tissue surrounding the right wrist. This finding indicated acute carpal tunnel syndrome, probably caused by pyogenic flexor tenosynovitis [Figure 2]. Furthermore, magnetic resonance imaging (MRI) of the right hand and wrist was conducted, revealing tenosynovitis with moderate effusion along the flexor tendons of the hand and wrist. The median nerve was also compressed [Figure 3]. This finding further confirmed our diagnosis of purulent tenosynovitis of the flexor tendon.Figure 2: Contrast-enhanced CT of the right-hand swelling for the digital flexor tendons (long tail arrows) with increased infiltration and fat stranding (arrowheads) in the surrounding soft tissue around the wristFigure 3: MRI of the right hand showing the compressed median nerve (short tail arrows)Hence, we administered antibiotics immediately and conducted an emergent exploration of the right wrist. The patient underwent a tenosynovectomy with decompression of the right median nerve. Postoperatively, the wound was left open and dressed with a moist saline dressing. Pus culture revealed penicillin-sensitive Staphylococcus aureus infection. She was hospitalized for 10 days and treated with intravenous cefazolin and clindamycin. On day 8 after admission, she underwent a second surgery for debridement of the right wrist with an advance flap from the right thigh. She was then discharged 4 days later. Post-discharge follow-up showed that she had fully recovered, and her wounds had healed well. Purulent flexor tenosynovitis of the fingers is a relatively common but often overseen inflammatory condition. Despite timely treatment, patients may still develop significant complications, including pain, swelling, stiffness, and ultimately, compromised function of the hand. Complication rates could be as high as 38%. Comorbidities, such as diabetes, peripheral vascular disease, and renal failure, are associated with a significant risk of amputation in patients with purulent flexor tenosynovitis.[6] This case report indicated that if diagnosis and treatment are given promptly, complications can be prevented in patients with such comorbidities. Usually, purulent flexor tenosynovitis arises from a small penetrating trauma over the volar proximal interphalangeal or distal interphalangeal joints; however, a small trauma could be overlooked by some patients. For instance, our patient denied any trauma or wounds on her right hand. Therefore, early recognition and surgical consultation are crucial in treating patients with purulent flexor tenosynovitis. More importantly, approximately 50% of patients with this condition show only one or two Kanavel’s signs. Thus, the presence of any of the Kanavel’s signs should be an alarming sign of flexor tenosynovitis.[4] In this case, our patient exhibited all four Kanavel’s signs, strongly suggesting purulent tenosynovitis. However, the specificity of Kanavel’s signs has been reported to be 51%–69%, indicating that sometimes, surgeons are operating on patients with finger cellulitis instead of flexor tenosynovitis, causing unnecessary morbidities.[7] Contrast-enhanced CT could increase the accuracy of flexor tenosynovitis diagnosis. A previous study evaluated the ratio of tendon sheath/tendon in CT scans in a patient cohort with flexor tenosynovitis and another patient cohort with finger cellulitis; results revealed that CT ratios can help identify flexor tenosynovitis.[8] CT scans could play an important role in diagnosis, either when used on their own or in combination with Kanavel’s signs. This diagnostic method significantly increases the specificity of flexor tenosynovitis identification. Moreover, MRI can identify the extent of the infection but cannot differentiate flexor tenosynovitis from other inflammatory conditions. Thus, MRI should be used when ruling out other conditions similar to flexor tenosynovitis.[9] In conclusion, although infectious flexor tenosynovitis is a well-known condition to emergency physicians, it still has no golden standard for its diagnosis. By combining the evaluation of contrast-enhanced CT scans arranged in patients with finger infections and the identification of any Kanavel’s signs, the accuracy in the diagnosis of flexor tenosynovitis could be improved. Ethics statement This study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki and its amendments. The authors certify that they have obtained the patient’s consent for her picture, image and other clinical information to be reported in this journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal the identity. Author contributions Resources and visualization, Shen-Chau Huang; original draft preparation and editing, Yi-Lun Tsai. All authors have read and agreed to the final version of the manuscript. Data availability statement All data generated or analyzed during this study are included in this published article. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.