Elongated muscle belly of the flexor digitorum superficial causing carpal tunnel syndrome

Background

Carpal tunnel syndrome (CTS) is by far the most common entrapment neuropathy (Adams et al. Am J Ind Med 25:527–536, 1994; Cheadle et al. Am J Public Health 84:190–196, 1994; Stevens et al. Neurology 38:134–138, 1988). A combination of described symptoms, clinical findings and electrophysiological testing is used to confirm the diagnosis. Several studies have suggested that in patients with a clinical diagnosis of CTS, the accuracy of nerve sonography is similar to that for electromyography (Chen et al. BMC Med Imaging 11:22, 2011; Guan et al. Neurol Res 33:970–953, 2011; Kele et al. Neurology 61:389–391, 2003; Tai et al. Ultrasound Med Biol 38:1121–1128, 2012). In special cases though, the nerve sonography can reveal the cause of the median entrapment neuropathy (Fumière et al. JBR-BTR 85:1–3, 2002; Kele et al. J Neurosurg 97:471–473, 2002; Kele et al. Neurology 61:389–391, 2003; Zamora et al. J Clin Ultrasound 39:44–47, 2011).

Methods

A 43-year-old farmer was admitted to our department with 1 year of intermittent pain in the left hand and numbness of the thumb, index and middle finger. The pain and the numbness could be reproduced by extension of the wrist and fingers. The electrophysiological testing revealed signs of an entrapment median neuropathy in carpal tunnel.

Results

The high-resolution sonography (18 MHz) revealed signs of entrapment neuropathy with increased cross-sectional area, disturbed echostructure of the nerve and pathological wrist-to-forearm ratio, confirming the results from a similar study (Kele et al. Neurology 61:389–391, 2003). In addition, an elongated muscle belly of the flexor digitorum superficialis in the carpal tunnel could be identified. During the extension of the wrist and fingers, a greater protrusion of the muscle belly could be demonstrated causing compression of the median nerve.

Conclusions

We present a video case report of the sonographic findings of a patient diagnosed with carpal tunnel syndrome due to an elongated muscle belly of the flexor digitorum superficialis in the carpal tunnel. Our case highlights the importance of nerve sonography in the differential diagnosis of the cause of a carpal tunnel syndrome. With the aid of ultrasonography, it is possible to obtain very important information concerning different aspects of this case. First, in showing the presence of the elongated muscle belly of the flexor digitorum superficialis, the cause of the symptoms could be explained. Second, it was possible through the ultrasound study to explain the atypical clinical appearance in this case, demonstrating the compression neuropathy only after extension of the wrist and fingers. There have been no previous reports in which authors described an elongated muscle belly as cause of a CTS. Third, and perhaps most important, ultrasonography had a direct influence on our selection of therapeutical strategy and approach. As a result, we recommended in this patient a surgical therapy to completely solve the problem, but the patient declined this option and preferred a conservative therapy with a hand orthosis to prevent wrist extension. In conclusion we recommend ultrasonography as a very useful method in the diagnostic evaluation of carpal tunnel syndrome. We have clearly demonstrated that ultrasonography can be used to discover the cause of median nerve compression, especially in cases with an atypical clinical presentation.

Electronic supplementary material

The online version of this article (doi:10.1007/s11552-012-9435-z) contains supplementary material, which is available to authorized users.     

Intraoperative electroneurography during median nerve decompression in carpal tunnel syndrome

Summary In 17 patients with the diagnosis of carpal tunnel syndrome, orthodromic sensory nerve conduction measurements during ligament division and internal neurolysis were performed without the use of a pneumatic tourniquet. While ligament division led to an increase in conduction velocity (p < 0.05; median increase 0.7 m/s), it did not result in a significant change of the amplitude. During internal neurolysis, an increase of the sensory nerve potential (p<0.01; median increase 0.9 V) and no significant change in conduction velocity were observed. We conclude that internal neurolysis does not cause a disruption of nerve function during the operation.     

超声引导下正中神经阻滞对腕管综合征治疗效果的影响

目的观察超声引导下正中神经阻滞治疗腕管综合征的临床效果。方法选择40例(69个患腕)腕管综合征患者,性别不限,年龄33~61岁,ASAⅠ或Ⅱ级。随机分为超声组(U组)和对照组(C组),每组20例。U组采用超声引导下正中神经阻滞,C组采用解剖标志定位正中神经阻滞,两组每次阻滞药物均为布比卡因4.5mg、曲安奈德5mg、维生素B12 100μg混合液3ml。通过Boston腕管问卷调查表(BCTQ)评估患者治疗前后手症状和功能;记录治疗前后正中神经电生理参数;记录二次治疗及不良反应情况。结果与治疗前比较,治疗后1个月两组BCTQ评分中的症状严重程度评分(SSS)和功能状态评分(FSS)明显降低(P0.05),且U组SSS明显低于C组(P0.05),两组FSS差异无统计学意义。与治疗前比较,治疗后1个月两组运动潜伏期(MDL)、感觉潜伏期(SDL3)明显缩短(P0.05),感觉神经传导速度(SNCV)明显增快(P0.05),而运动神经传导速度(MNCV)差异无统计学意义。治疗后1个月,U组SNCV明显快于C组(P0.05),其余神经电生理参数两组差异无统计学意义。U组二次治疗及不良反应明显少于C组(P0.05)。结论采用超声引导下神经阻滞治疗腕管综合征能显著改善患者的手部症状,减少并发症。     

Acute carpal tunnel syndrome due to a hemangioma of the median nerve

Hemangioma of the median nerve presenting as acute carpal tunnel syndrome is unusual A-18- year old male presented with severe incapacitating pain of sudden onset of left forearm and hand after manual field work. There was swelling on volar aspect of forearm, with hyperalgesia in the median nerve distribution. The fingers and wrist were inmarked flexion and the patient did not allow wrist and finger extension. X-rays were within normal limits. An emergency volar carpal ligament release revealed, haematoma about 100 ml with numerous vessels encircling the median nerve. Histopathology of lesion turned out to be a cavernous hemangioma. Post operatively patient had full recovery.     

Anomalous muscle belly of the flexor digitorum superficialis associated with carpal tunnel syndrome: case report.

A patient had a 10-year history of pain and swelling in the right wrist and palm. Carpal tunnel exploration showed anomalous muscle bellies of flexor digitorum superficialis II and III. The muscle bellies were excised. Postoperatively, the symptoms disappeared. Our case is compared with others in the literature.     

复发的腕管综合征的显微外科治疗

目的 探讨复发的腕管综合征(CTS)的显微外科治疗效果. 方法 2001年6月至2009年12月采用显微神经松解联合带血管蒂小鱼际皮下脂肪瓣(HTFPF)治疗21例复发的CTS患者,男5例,女16例;年龄35～78岁,平均52.2岁.17例采用腕管切开松解减压术后复发,4例采用内镜下腕管松解术后复发.术后复发时间5 ～35个月,平均19.6个月.按照CTS分型:中度8例,重度13例.所有患者桡侧3～4个手指麻木、疼痛,有麻刺感;Tinel征均阳性;食指指腹两点分辨觉5～14mm,平均9.3mm;握力6～18 kg,平均11.7 kg.所有患者复发后采取保守治疗3周均无效.结果 21例患者术后获18 ～48个月(平均24.4个月)随访.正中神经卡压症状明显改善时间2～14d,平均7.2d;两点辨别觉提高至2～8mm,平均4.0 mm;握力18～37 kg,平均23.5 kg.所有患者手指活动、感觉正常,麻木、针刺感消失,无明显的腕部疼痛,拇指对掌功能正常,肌电图检查均阴性,Tinel征、Phalen征、Reverse Phalen征均阴性.术后18个月,按CTS功能评定标准:优16例,良4例,可1例,优良率为95.2％,腕部主观疼痛减轻率达100％.所有患者均恢复正常工作和生活.全部患者术后未出现支柱疼痛、小鱼际疼痛、反射性交感神经营养不良、正中神经及其返支、掌浅弓损伤等并发症. 结论 显微外科治疗是治疗复发的CTS的有效方法,显微神经松解联合HTFPF可以恢复正中神经的滑动,并提供良好的软组织营养基床,显著改善复发的CTS患者的症状.     

Acute carpal tunnel syndrome produced by anomalous flexor digitorum superficialis indicis muscle

A 23 year old female nurse developed acute sensory symptoms of median nerve compression. Early exploration revealed abnormal flexor superficialis indicis muscle as the compressing structure. Symptoms were relieved by freeing the muscle from the nerve.     

108例腕管综合征正中神经传导测定结果分析

分析１０８例腕管综合征正中神经传导测定结果，以求最敏感的电诊断指标。比较１０８例正中神经复合肌肉动作电位，肘至腕的运动传导速度测定及指至腕部的感觉神经动作电位三项。指标异常检测率，表明拇指至腕段的感觉传导速度减慢是最敏感的电诊断参量。１０８例中伴有前臂段运动传导速度减慢的占１０．５％。同组病例无症状上肢出现电生理异常者为２０％，指示有亚临床的腕管部神经卡压存在的可能。     

Carpal tunnel syndrome secondary to an accessory flexor digitorum superficialis muscle belly: case report and review of the literature

Anomalous muscles usually do not cause symptoms but are of academic interest mainly discovered during cadaveric dissection. An aberrant muscle belly arising from the index finger flexor digitorum superficialis tendon causing carpal tunnel syndrome is rare. The management of such an anatomical variant is dependent on whether the median nerve compression is associated with a palpable mass. A brief case highlighting important management principles along with a complete literature review is reported.     

Evaluation of sensory function after median nerve decompression in carpal tunnel syndrome using the current perception threshold test

The recovery level for sensory function after carpal tunnel release for the treatment of idiopathic carpal tunnel syndrome (CTS) was assessed with the current perception threshold (CPT) test. Seventeen CTS patients (21 hands) were followed, and the CPTs at the index finger of each patient was measured preoperatively and at 1, 3, and 6 months postoperatively. After carpal tunnel release, there was significant recovery of CPT at all stimulation frequencies, indicating improvement of all sensory functions including sensations of temperature, pain, touch, and vibration.     

Bifid median nerve as a determinant of carpal tunnel syndrome recurrence after endoscopic procedures. A case report

A number of complications have been associated with endoscopic technique in treating carpal tunnel syndrome (CTS). We observed a female patient who had previously undergone endoscopic surgery for CTS. Shortly after surgery, this patient complained of pain, numbness and strength deficiency, as severe as it was before the operation. A new, open, surgical procedure was performed. During this second-look surgery, we found a bifid median nerve, which divided into two branches at the second third of the forearm, proximal to the flexor retinaculum. We strongly suggest a careful exploration of the median nerve in the carpal tunnel. Moreover, we believe that an extensive preoperative assessment of median nerve morphology and function is mandatory prior to endoscopic approach in treating CTS.     

腕管综合征治疗研究进展

目的对腕管综合征(carpal tunnel syndrome,CTS)的治疗研究现状作一综述。方法查阅近年来国内外CTS治疗的相关文献,进行分析总结。结果腕夹板、类固醇适用于轻、中度CTS患者,近期效果显著;治疗后复发的CTS患者需采取手术治疗。主要术式为腕管松解术,包括腕管切开松解减压术(传统型和小切口型)、内镜下腕管松解减压术等。结论 CTS的最佳治疗方法尚无定论,部分学者推荐首选手术治疗。     

腕管综合征内窥镜手术预防正中神经损伤的临床研究

目的 介绍腕管综合征内窥镜手术(endoscopic carpal tunnel release,ECTR)预防正中神经损伤并发症的方法.方法 利用彩色多普勒超声仪(B超)对37例74手患者术前进行检测.结果 71例正中神经走行在桡侧腕屈肌腱与掌长肌腱之间,3例走行在掌长肌腱与尺侧腕屈肌腱之间,并术中确认.结论 正中神经变异走行在掌长肌腱与尺侧腕屈肌腱之间是ECTR的禁忌证,B超能准确定位正中神经与掌长肌腱关系,避免内窥镜手术损伤正中神经,更具有简单、经济、方便可靠等优点.

Abstract：

Objective To introduce a method of preventing median never injury during endoscopic carpal tunnel release (ECTR). Methods Ultrasonography of both wrists was done to 37 patients of carpal tunnel syndrome who were going to undergo open release of the transverse carpal ligament. Structures in the carpal tunnel were visualized to guide surgical decision-making. Results Ultrasonography showed that median never lies between the tendon of flexor carpi radialis and palmaris longus in 71 patients and lies between the tendon of palmaris longus and flexor carpi ulnaris in 3 patients. These findings were confirmed during the surgeries. Conclusion It is a contraindication of ECTR if median never lies between palmaris longus and flexor carpi ulnaris. Ultrasonography can accurately reveal the relative position of median never to the palmaris longus tendon. Pre-operative ultrasonography of the wrist is a simple, inexpensive and convenient method to exclude these contraindications and thus prevent median never injuries in ECTR.     

感觉过敏型腕管综合征的治疗

目的 报道7例感觉过敏型腕管综合征的诊治特点.方法 收集与分析2002年3月至2005年3月间128例腕管综合征中感觉过敏型7例的病情及治疗特点.其中女性4例、男性3例.4例应用内镜治疗,3例切开治疗,经1～4年随访,平均随访时间1.5年.结果 内镜治疗中2例疗效差,均在术中插入扩张导管时出现异常疼痛,另外2例基本满意.3例切开治疗中,2例疗效差,1例基本满意.3例基本满意中,2例内镜插入导管时均未出现疼痛,另1例为单纯切断腕横韧带,并在神经外膜下注射激素.结论 感觉过敏型腕管综合征是一组特殊病例,保护神经外膜是治疗关键.     

Ultrasonographic median nerve changes under tendon gliding exercise in patients with carpal tunnel syndrome and healthy controls

Study designCase control study.Purpose of the studyTo evaluate the ultrasonographic median nerve changes under tendon gliding exercise in patients with carpal tunnel syndrome (CTS) and healthy controls.MethodsSeventy-three patients with CTS and 53 healthy volunteers were consecutively recruited. Each subject underwent a physical examination, nerve conduction studies and ultrasonographic examinations of the median nerve during tendon gliding exercises.ResultsSignificant changes in the cross-sectional area of the median nerve were found while moving from the straight position to the hook position and from the hook position to the fist position. There were also significant changes in the flattening ratio when moving from the hook position to the fist position.ConclusionsUltrasonography revealed that the median nerve was compressed in the fist position in both CTS patients and healthy volunteers. Thus, forceful grasping should be avoided during tendon gliding exercises performed in the fist position.Level of evidence3b     

Histopathology of the flexor tendon sheaths and its relevance in idiopathic carpal tunnel syndrome

Compression of the median nerve in the carpal tunnel can be produced by a variety of factors, including fractures, metabolic disturbances, rheumatoid arthritis or anatomical anomalies. When it is not possible to identify a specific cause, the term ”idiopathic carpal tunnel syndrome” is used. Although this disease is very common, its pathophysiology is still unclear. In the past, the presence of a chronic non-specific tenosynovitis around the flexor tendons was postulated but several investigations failed to show any inflammatory reaction in the carpal synovium. In this study, the histology of the flexor tendon sheaths in a group of 50 patients surgically treated for idiopathic carpal tunnel syndrome (ICTS) have been investigated both from the qualitative (histopathology) and quantitative (micrometric evaluation) points of view. Lack of acute or chronic inflammatory cells, connective disorganization, and vascular modifications are the main histological findings which are present in all the specimens, regardless of the patient’s age, the duration of the sensory symptomatology or the severity of the neurological lesion on EMG exam. The carpal synovium in these patients appeared thickened when compared to the specimens obtained from the control group. However, on micrometric evaluation a relationship between synovial thickness and severity of the symptomatology or of the EMG data was not observed. The carpal synovium in ICTS has a consistent histological appearance and is increased in thickness when compared with normal specimens. Received: 18 September 1998 / Accepted: 14 April 1999     

The use of diagnostic ultrasound in carpal tunnel syndrome

PURPOSE: Traditional evaluation of suspected carpal tunnel syndrome (CTS) involves a thorough history, physical examination, and nerve conduction velocity studies (NCS). Ultrasound is used widely in Europe and has gained acceptance in the United States in the diagnosis of various musculoskeletal disorders. The purpose of this study was to document the ultrasonographic measurement difference in median nerve size between patients with CTS and controls and to correlate these findings with NCS findings, thereby allowing us to test the validity of ultrasound as a diagnostic modality for CTS. METHODS: Forty-four wrists in 26 CTS patients and 86 wrists in 43 asymptomatic volunteers were imaged using a real-time ultrasound scanner with a 12/5 MHz linear-array transducer. The cross-sectional area of the median nerve was measured at the level of the distal wrist crease in both CTS patients and controls. All CTS patients had NCS. The ultrasonographic median nerve area was compared for the 2 groups and correlation analysis between ultrasonographic nerve sizes and NCS findings was performed. RESULTS: The average cross-sectional area of the median nerve at the distal wrist crease was 9 mm(2) in asymptomatic volunteers and 14 mm(2) in CTS patients. For the CTS patients the Pearson correlation coefficient between ultrasound nerve measurement and NCS values was 0.37, suggesting that higher values of ultrasound measurements are associated with abnormal NCS findings. CONCLUSIONS: Our results indicate that high-resolution ultrasound is informative in the evaluation of CTS and shows enlargement of the median nerve at the distal wrist crease in symptomatic patients. Therefore it is a reliable modality for imaging the wrist in patients with CTS. In addition ultrasound is well tolerated and safe. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic, Level I.