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IMAGING Flexor Carpi Radialis Tenosynovitis Mimicking Carpal Tunnel Syndrome Diagnosed and Monitored with Ultrasound: Case Report Chandler L. Bolles 1 & Ahmad Abdella 1 & Patrick J. Battaglia 1 Accepted: 12 May 2020 # Springer Nature Switzerland AG 2020 Abstract The purpose of this report is to describe the value of ultrasound in diagnosing and monitoring flexor carpi radialis (FCR) tenosynovitis clinically mimicking carpal tunnel syndrome. A 62-year-old female had chronic right wrist pain with numbness and tingling in the first four digits. Physical examination suggested carpal tunnel syndrome. Ultrasound and power Doppler images demonstrated tenosynovitis of the FCR tendon, but a normal median nerve. Hyperemia was extending from the inflamed tendon to the adjacent median nerve, suggesting the FCR tenosynovitis was inducing a low-grade neuritis. Follow-up ultrasound at 3 weeks was performed due to worsening symptoms and demonstrated consistent tenosynovitis, prompting additional labo- ratory testing which excluded an inflammatory arthritis. More aggressive therapy was introduced at this time and repeat ultra- sound 6 weeks later demonstrated near resolution of FCR tenosynovitis coinciding with symptom amelioration. This case underscores the value of ultrasound as an extension of the musculoskeletal examination to improve diagnostic specificity and guide appropriate care. Keywords Ultrasound . Flexor carpi radialis . Tenosynovitis . Carpal tunnel syndrome Introduction The flexor carpi radialis (FCR) tendon is superficial to the scaphoid and inserts at the base of the second and third meta- carpals (Fig. 1)[1]. The FCR tendon is encased by a fibro- osseous tunnel formed by a vertical retinacular septum adja- cent to the flexor retinaculum of the carpal tunnel. This fibro- osseous tunnel makes it particularly susceptible to mechanical compression as the FCR tendon occupies 90% of available space [2]. The distal borders of this fibro-osseous tunnel con- sist of the retinacular septum anteriorly, the carpal tunnel me- dially, and the scaphoid-trapezoid joint posterolaterally [1]. Due to their anatomic proximity, disorders of the FCR tendon (e.g., tenosynovitis) may mimic disease at the base of the thumb (e.g., osteoarthritis) or carpal tunnel syndrome (CTS) [35]. Ultrasonography (US) is widely used for evaluation of wrist and hand pathology [6]. Recent evidence supports US in the evaluation of tenosynovitis at the wrist [7, 8], while also providing real-time patient interaction. Also, US has high sen- sitivity for many hand and wrist pathologies, is widely acces- sible, low cost, and lacks ionizing radiation [6]. Limited reports exist describing disorders of the FCR ten- don mimicking other conditions causing volar wrist pain. We present a case of FCR tenosynovitis that mimicked CTS clin- ically and was diagnosed and monitored through treatment with US. We also discuss the strengths and limitations of US at the point of care in this case of FCR tenosynovitis. Case Informed consent was obtained to publish the patients de- identified healthcare information. A 62-year-old Lebanese female presented with chronic right wrist pain that wors- ened 2 months prior after using her right hand to climb into a car. She denied any recent surgeries or trauma to the right wrist. Her past medical history was significant for hyper- tension and hypercholesterolemia. At presentation, she re- ported numbness and tingling in digits 14, pain at the base This article is part of the Topical Collection on Imaging * Chandler L. Bolles [email protected] 1 Chiropractic Health Center, Logan University, 1851 Schoettler Road, Chesterfield, MO 63017, USA SN Comprehensive Clinical Medicine https://doi.org/10.1007/s42399-020-00320-1 /Published online: 27 May 2020 (2020) 2:797801

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Page 1: Flexor Carpi Radialis Tenosynovitis Mimicking Carpal ... · The distal borders of this fibro-osseous tunnel con-sist of the retinacular septum anteriorly, the carpal tunnel me-dially,

IMAGING

Flexor Carpi Radialis Tenosynovitis Mimicking Carpal TunnelSyndrome Diagnosed and Monitored with Ultrasound: Case Report

Chandler L. Bolles1 & Ahmad Abdella1 & Patrick J. Battaglia1

Accepted: 12 May 2020# Springer Nature Switzerland AG 2020

AbstractThe purpose of this report is to describe the value of ultrasound in diagnosing and monitoring flexor carpi radialis (FCR)tenosynovitis clinically mimicking carpal tunnel syndrome. A 62-year-old female had chronic right wrist pain with numbnessand tingling in the first four digits. Physical examination suggested carpal tunnel syndrome. Ultrasound and power Dopplerimages demonstrated tenosynovitis of the FCR tendon, but a normal median nerve. Hyperemia was extending from the inflamedtendon to the adjacent median nerve, suggesting the FCR tenosynovitis was inducing a low-grade neuritis. Follow-up ultrasoundat 3 weeks was performed due to worsening symptoms and demonstrated consistent tenosynovitis, prompting additional labo-ratory testing which excluded an inflammatory arthritis. More aggressive therapy was introduced at this time and repeat ultra-sound 6 weeks later demonstrated near resolution of FCR tenosynovitis coinciding with symptom amelioration. This caseunderscores the value of ultrasound as an extension of the musculoskeletal examination to improve diagnostic specificity andguide appropriate care.

Keywords Ultrasound . Flexor carpi radialis . Tenosynovitis . Carpal tunnel syndrome

Introduction

The flexor carpi radialis (FCR) tendon is superficial to thescaphoid and inserts at the base of the second and third meta-carpals (Fig. 1) [1]. The FCR tendon is encased by a fibro-osseous tunnel formed by a vertical retinacular septum adja-cent to the flexor retinaculum of the carpal tunnel. This fibro-osseous tunnel makes it particularly susceptible to mechanicalcompression as the FCR tendon occupies 90% of availablespace [2]. The distal borders of this fibro-osseous tunnel con-sist of the retinacular septum anteriorly, the carpal tunnel me-dially, and the scaphoid-trapezoid joint posterolaterally [1].Due to their anatomic proximity, disorders of the FCR tendon(e.g., tenosynovitis) may mimic disease at the base of thethumb (e.g., osteoarthritis) or carpal tunnel syndrome (CTS)[3–5].

Ultrasonography (US) is widely used for evaluation ofwrist and hand pathology [6]. Recent evidence supports USin the evaluation of tenosynovitis at the wrist [7, 8], while alsoproviding real-time patient interaction. Also, US has high sen-sitivity for many hand and wrist pathologies, is widely acces-sible, low cost, and lacks ionizing radiation [6].

Limited reports exist describing disorders of the FCR ten-don mimicking other conditions causing volar wrist pain. Wepresent a case of FCR tenosynovitis that mimicked CTS clin-ically and was diagnosed and monitored through treatmentwith US. We also discuss the strengths and limitations of USat the point of care in this case of FCR tenosynovitis.

Case

Informed consent was obtained to publish the patient’s de-identified healthcare information. A 62-year-old Lebanesefemale presented with chronic right wrist pain that wors-ened 2 months prior after using her right hand to climb intoa car. She denied any recent surgeries or trauma to the rightwrist. Her past medical history was significant for hyper-tension and hypercholesterolemia. At presentation, she re-ported numbness and tingling in digits 1–4, pain at the base

This article is part of the Topical Collection on Imaging

* Chandler L. [email protected]

1 Chiropractic Health Center, LoganUniversity, 1851 Schoettler Road,Chesterfield, MO 63017, USA

SN Comprehensive Clinical Medicinehttps://doi.org/10.1007/s42399-020-00320-1

/Published online: 27 May 2020

(2020) 2:797–801

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of the thumb, and a weak grip from pain. Her grip deficitwas most impactful on her activities of daily living. Thepatient had been using an over the counter splint, for whichthe make and model are not known, as well as applyingheat or ice per their preference with minimal change insymptoms. Inspection and palpation of the right wrist re-vealed good muscle tone and an immobile, tender swellingon the right forearm proximal to the wrist. The thumb andproximal wrist were also tender on palpation. Active andpassive ranges of motion were restricted in all planes dueto pain. Ischemic compression of the median nerve in-creased tingling in the hand. Hypoesthesia was present ina median nerve distribution (palmar digits 1–4) duringcompression of the nerve at the distal wrist crease. Phalenand Tinel testing were negative. Point of care US revealeda thickened retinaculum at the FCR tendon, internal het-erogeneity, and surrounding Doppler positivity consistentwith FCR tendinopathy and tenosynovitis (Fig. 2). Thedegree of tenosynovi t i s overshadowed the mildtendinopathy. The median nerve was normal in cross-sectional area and appearance. The tenosynovitis was pre-sumed to be degenerative/overuse in origin, and a trial ofcare for 3 weeks was initiated and consisted of low-level

laser therapy, activity modification (i.e., avoidance of wristand thumb movement when feasible), and the introductionof a spica splint to be used during the day when feasibleand at night while sleeping. At 3 weeks, there was noimprovement of symptoms, including no change in report-ed hand sensations. Point of care US was again utilized andrevealed persistent tenosynovitis, with proximity betweenthe median nerve and inflamed FCR sheath (Figs. 3 and 4).The median nerve was again normal at US, except forsurrounding hyperemia from FCR tenosynovitis (Fig. 4).Radiographs and a blood panel (ESR, CRP, rheumatoidfactor, ANA, ANCA) were ordered at this time and werenormal, excluding inflammatory causes of tenosynovitis.The patient declined pharmacologic intervention. Sincethe working diagnosis was mechanical tenosynovitis in-ducing a presumed low-grade median neuritis, and the pa-tient had been refractory to care, more intensive treatmentwas initiated. This included manual soft tissue and jointmobilization and a home icing program. The wrist splintwas also discontinued, and home exercises were pre-scribed. After 6 more sessions at one per week frequency,the patient reported minimal pain, mostly in the thumb, andhad returned to full daily activities without reported grip

Fig. 2 Right (A) and left (B)short-axis images of the flexorcarpi radialis tendon (FCR) at thescaphoid at initial presentation.On the symptomatic right side,there is marked thickening of theretinaculum (arrow) comparedwith the left, consistent withtenosynovitis

Fig. 1 The flexor carpi radialis muscle originates from the humerusepitrochlea and its tendon descends deep to the antebrachial fascia toinsert onto the base of the 2nd and 3rd metacarpals after coursingthrough a fibro-osseous tunnel formed by the scaphoid, the flexor reti-naculum, a vertical retinacular septum and the trapezium. Adapted from

Flexor carpi radialis muscle, In Wikipedia, The Free Encyclopedia.Retrieved 16:43, December 4, 2019, from https://en.wikipedia.org/w/index.php?title=Flexor_carpi_radialis_muscle&oldid=910054465

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impairment. An updated ultrasound documented improve-ment in tenosynovitis (Fig. 5).

Discussion

We present a unique case of FCR tenosynovitis mimickingCTS. This case highlights the value and limitations of point ofcare US in the diagnosis.

Tenosynovitis of the FCRmay be secondary to osteoarthri-tis at the thumb base, underlying FCR tendinopathy, inflam-matory arthritis, or scaphoid fractures [9, 10]. Individuals withtenosynovitis may complain of focal wrist pain exacerbatedby extension and dysesthesia in the distribution of the palmarcutaneous branch of the median nerve (PCBMN) [9]. ThePCBMN is the last collateral branch of the median nerveand runs parallel to the ulnar side of the FCR tendon. Onereport demonstrated that tenosynovitis of the FCR, as presentin this case, may contribute to PCBMN neuritis [3]. Our pa-tient did not have paresthesia confined to this distribution, butrather to digits 1–4 suggesting tenosynovitis induced neuritisof the median nerve itself and not just the PCBMN.

Spinner et al. describe that tenosynovitis at the wrist mayproduce symptoms of numbness associated with fullness ofthe soft tissues [11]. These patients may also have swelling inthe distal aspect of the forearm as well as characteristic symp-toms of CTS [11]. Sein Oh et al. reported on three officeworkers with tenosynovitis and symptoms of hand paresthesiain the absence of nerve compromise on electrodiagnostic

evaluation [12]. The exact distribution of paresthesia wasnot discussed. The patient in our case presented with pares-thesia that extended in a median nerve distribution. This atyp-ical presentation is unlikely to be the result of tenosynovitisalone, but rather, tenosynovitis with induced low-gradeneuritis.

Extensive data exists supporting the use of US in the diag-nosis of CTS and there is growing evidence that high-resolut ion US may be used as an al ternat ive toelectrodiagnostic studies [13]. A cross-sectional area of10 mm2 or greater of the median nerve at the level of thepisiform bone or tunnel inlet is the most commonly used pa-rameter to diagnose CTS on US, and sensitivity has beenreported to be as high as 97.9% [13, 14]. There is class I andclass II evidence that median nerve CSA at the wrist is accu-rate for the diagnosis of CTS [15]. For these reasons, it wasfelt the normal US was diagnostic in our case to exclude en-trapment neuropathy of the median nerve, prohibiting morecostly and invasive electrodiagnostic testing. Additionally,10–15% of patients with clinically defined CTS have normalnerve conduction studies [16]. An unremarkableelectrodiagnostic study does not exclude CTS, but it changesthe likelihood of significant axonal loss or conduction block[16].

There are likely different treatment options and prognosticimplications between FCR tenosynovitis and CTS, highlight-ing the importance of image-aided diagnosis. Updated man-agement and prognosis for FCR tenosynovitis is primarilyguided by case reports. One report outlines a case of FCR

Fig. 3 Short-axis images of the right flexor carpi radialis tendon (FCR),with (A) more proximal than (B), 3 weeks after initial presentation. Thearrow in (A) highlights the anechoic fluid collecting within the synovialsheath, consistent with tenosynovitis. In (B), note the proximity of the

median nerve (MN), to the FCR. Likely, the tenosynovitis induced a localneuritis in this patient, resulting in the clinical symptoms of carpal tunnelsyndrome. Note in (B), the hypoechogenicity seen within the carpal tun-nel is the result of anisotropy and is not pathologic

Fig. 4 Short-axis images powerDoppler images of the right flexorcarpi radialis tendon (FCR), with(A) more proximal than (B),3 weeks after initial presentation.There was interval worsening ofthe hyperemia, despite treatment.Again note the proximity of themedian nerve (MN)

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tenosynovitis in a 38-year-old male construction worker treat-ed with an injection of betamethasone [3]. The patient report-ed resolution of symptoms at 5-month follow-up. Conversely,for CTS treatment, a 2018 systematic review reported thatcorticosteroid injections provided greater short-term reliefthan oral steroids in patients with CTS [17]. However, reliefwas not sustained in the long term. One prospective studydemonstrated greater decreases in median nerve CSA aftersurgical decompression of the flexor retinaculum comparedwith nonsurgical management [18].

Our case is particularly significant as it demonstrates therole US can play in the diagnosis of volar wrist pain mimick-ing carpal tunnel syndrome. As the patient’s median nerveCSA was normal, CTS was effectively ruled out and anotherdiagnosis was pursued [13]. This does not discount low-grademedian neuritis as contributing to the patient’s symptoms.Rather, intervention aimed at targeting the tenosynovitis alonewas helpful. However, US imaging was not enough to ensurea proper diagnosis in this case requiring augmentation withlabs for confirmation.

Limitations

Inherent to any case report, inferences of treatment successcannot be made independent of natural history.

Conclusion

We present a unique case of FCR tenosynovitis mimickingCTS and highlight the role of US at the point care in its diag-nosis. It is important that healthcare professionals are aware ofthe clinical implications this condition can have on manage-ment of patients presenting with volar wrist pain anddysesthesia. Future research should aim to examine the inci-dence and prevalence of FCR tenosynovitis mimicking CTSin volar wrist pain as management and prognosis for these twoconditions are different.

Compliance with Ethical Standards

The patient provided written informed consent for the inclusion of infor-mation that could potentially lead to her identification.

The case presented does not include any experimental proceduresinvolving humans or animals.

Conflict of Interest The authors declare they have no conflicts ofinterest.

References

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Fig. 5 Short-axis (A) and long-axis (B) images of the right flexor carpiradialis tendon (FCR), at final visit when the patient was nearly asymp-tomatic and had resumed all activities of daily living. Note the near

resolution of the fluid surrounding the tendon, correlating with the re-duced symptoms

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Publisher’s Note Springer Nature remains neutral with regard to jurisdic-tional claims in published maps and institutional affiliations.

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