Ultrasonographic assessment of carpal tunnel syndrome of mild and moderate severity in diabetic patients by using an 8-point measurement of median nerve cross-sectional areas

ABSTRACT: BACKGROUND: Using high-resolution ultrasonography (US) to measure the median nerve cross-sectional areas (CSAs) such as in the "inching test" conducted in nerve conduction studies is a valuable tool to assess carpal tunnel syndrome (CTS). However, using this US measurement method to assess the median nerve CSA in diabetic patients with CTS has rarely been reported. Therefore, we used this US measurement method in this study to measure median nerve CSAs and to compare the CSAs of idiopathic, diabetic and diabetic polyneuropathy (DPN) patients with CTS. METHODS: 124 hands belonging to 89 participants were included and assigned into four groups: control (32), idiopathic (38), diabetic (38) and DPN (16) CTS. In the latter two groups, only patients with mild and moderately severity CTS were included. The median nerve CSAs were measured at 8 points marked as i4, i3, i2, i1, w, o1, o2, and 03 in the inching test. The measured CSAs in each group of participants were compared. RESULTS: Compared with the CSAs of the control group, enlarged CSAs were found in the idiopathic, diabetic and DPN CTS groups. The CSAs were larger at i4, i3 and i2 in the diabetic CTS group compared to the idiopathic CTS group. The CSAs measured at the i1 and w levels of the DPN CTS group were smaller than those of the diabetic CTS group. In the diabetic CTS group, the cut-off values of CSAs measured at the inlet, wrist crease, and outlet were 15.3 mm2, 13.4 mm2 and 10.0 mm2, respectively, and 14.0 mm2, 12.5 mm2 and 10.5 mm2, respectively, in the DPN CTS group. CONCLUSIONS: Compared with the median nerve CSAs of the control and idiopathic CTS groups, the median nerve CSAs of the diabetic patients with CTS were significantly enlarged. However, compared with the diabetic CTS group, the CSAs were significantly smaller in the DPN CTS group. This US 8-point measurement method can be of value as an important complementary tool for CTS studies and diagnosis among diabetic patients.     

正中神经前臂段运动传导与腕管综合征严重程度的相关性研究

目的：探讨正中神经前臂段运动传导（fMCV）与腕管综合征（CTS）疾病严重程度的相关性,并初步探讨其发生机制。方法：以符合纳入标准的CTS患者66例（126只患手）为病例组,年龄、性别匹配的96例健康志愿者的非利手为对照组,均行神经电生理检测。采用正中神经末端运动潜伏期（DML）和复合肌肉动作电位（CMAP）作为CTS严重程度指标,并研究其与fMCV的相关性。结果：①尺神经：病例组与对照组的各电生理参数间比较差异均无显著意义（t检验,P〉0．05）;②正中神经：在病例组（n=126）和对照组（n=96）,DML（ms）分别为5．0±1．3、3．0±0．3,腕-掌段正中神经运动传导速度（m／s）分别为22．2±7．3、56．9±8．3,fMCV（m／s）分别为53．7±5．5、59．2±3．6,拇短展肌CMAP波幅（mV）分别为7．3±2．9、10．1±1．9。以上所有参数的值均经t检验,P〈0．05,差异有显著意义;③相关性：在病例组,fMCV与DML呈负相关（r=-0．35,P〈0．05）,与拇短展肌CMAP呈正相关（r=0．18,P〈0．05）。结论：fMCV的异常与CTS患者的严重程度相关,且正中神经逆行性变为其可能的发生机制。     

The effect of the median nerve compression test on median nerve conduction across the carpal tunnel

INTRODUCTION: We conducted an experimental, single-blind research study to determine the efficacy of using the median nerve compression test (MNCT) to improve the sensitivity and specificity of median nerve motor and sensory latencies for the diagnosis of carpal tunnel syndrome (CTS). We expected post-MNCT latencies to be prolonged in the CTS group. METHODS: A convenience sample of 18 subjects aged 18-65 was enrolled in this study. The CTS group consisted of 9 subjects with 14 hands tested having clinical signs and symptoms of CTS and normal baseline latency measures. The control group consisted of 9 gender- and age-matched (+/- 3 years) subjects with 14 hands tested. Three standard distal sensory latencies (DSL) and one distal motor latency (DML) were obtained, then repeated after application of the MNCT. RESULTS: No significant differences in latencies were found between groups (p = 0.76) or within subjects (p = 0.74) after application of the MNCT. There was less than 10% increase in sensitivities of post-MNCT latencies. DISCUSSION AND CONCLUSION: We found that the MNCT did not cause a meaningful increase in sensitivity or specificity of latencies for the diagnosis of CTS. The use of the MNCT as a method to prolong standard latencies is not recommended.     

Tethered median nerve stress test in the diagnosis of carpal tunnel syndrome

The sensitivity of the Median Nerve Stress Test (Stress Test) described by La Ban et al. and performed hyperextending for one minute the supinated wrist and the distal interphalangeal joint of the index finger and looking for pain in the proximal forearm was evaluated in 140 arms with Carpal Tunnel Syndrome confirmed electrophysiologically. The Stress Test was positive in 60 hands (42.8%), the Phalen's sign in 79 (56.4%) and the Tinel's sign in 59 (42.1%). Hypoaesthesia to pinprick in the distribution of the median nerve was found in 45 hands (32.1%) and weakness or hypotrophia of thenar eminence in 17 (12.1%). In spite of his low sensitivity, in some cases the Stress Test was the only clinical positive sign and, in addition to electrophysiological examination, may be helpful in clinical practice.     

Numerical correlation between nerve conduction velocity and compound nerve action potential of median nerve in patients with carpal tunnel syndrome and normal group

BACKGROUND: Electrodiagnostic studies have a major role in the diagnosis of carpal tunnel syndrome (CTS). The parameters used in this regard include nerve conduction velocity (NCV) and compound nerve action potential (CNAP). In some individuals, recording sensory nerve action potential (SNAP) and as a result NCV is impossible. This study aims at determining the numerical correlation between CNAP and NCV calculated through SNAP METHODS: NCV and CNAP in 100 hands of 50 electrophysiologically and clinically asymptomatic individuals and 100 hands of 70 patients with CTS were surveyed. The correlation between NCV and CNAP was determined using independent t-test and regression model. RESULTS: The results indicated that there is a significant correlation between sex, group, CNAP and NCV statistically (P(value) < 0.05). Pearson correlation coefficient was -0.95. Agreement between NCV and CNAP was proved based on Bland Altman plot. CONCLUSIONS: There is numerical correlation between NCV and CNAP that we can use it when we are not able to calculate NCV through SNAP.     

掌到腕正中神经感觉传导速度在轻、中度腕管综合征诊断中的应用

目的：寻找诊断轻、中度腕管综合征（CTS）敏感的电生理检查方法。方法：对临床症状、体征符合CTS，电生理学检查为轻、中度的CTS患者24例（41手）和年龄、性别相匹配的健康对照组14例（28手），采用顺向性感觉神经传导速度（SCV）测定法分别测定指3-腕、指3-掌、掌-腕正中神经（MN）SCV及MN远端潜伏期（DML）。（重症CTS者因易于诊断，不列入本研究。）结果：掌到腕MN SCV％47．12m／s，考虑诊断CTS。在所有诊断轻、中度CTS的研究组中，指3到腕MNSCV减慢的占63％，掌到腕MNSCV减慢的占95％，指3到掌MNSCV减慢的占10％。结论：用指3刺激，腕记录和指3刺激，掌记录（掌至腕测量距离为7～8cm）来分别检测并计算出指3到掌和掌到腕段的SCV，在诊断轻度、中度CTS方面是一个非常敏感的方法，在怀疑CTS时此诊断方法可作为常规的电生理检查。     

An increased frequency of carpal tunnel syndrome in sarcoidosis. Results of a study based on nerve conduction study

Sarcoidosis is a systemic disease which affects the musculoskeletal system; however, its association with carpal tunnel syndrome (CTS) has been reported only rarely. In our study, we tried to determine the prevalence of CTS in our consecutive sarcoidosis patients based on their symptoms and nerve conduction study (NCS). Fifty-six patients (mean age: 45.2) who were followed up with the diagnosis of sarcoidosis at our center and who gave informed consent for NCS were included into the study. The patients were questionned for the presence of hand symptoms: paresthesia, pain, nocturnal paresthesia and/or pain, and, they underwent NCS. Ten (17.9%) patients had recurrent paresthesia, 12 (21.4%) had pain, and 8 (14.3%) had nocturnal paresthesia and/or pain. The results of NCS showed that 41% of the patients had findings compatible with CTS. Extrapulmonary involvement was significantly more frequent in these patients when compared to patients without CTS (p=0.04). Also, patients with CTS were older than the others and CTS-associated symptoms were more frequent in them although this was not significant (p>0.05). In this study, by performing NCS we detected quite a high prevalence of CTS in our sarcoidosis patients. The fact that most of the patients were asymptomatic was interesting.     

Role of fasciae around the median nerve in pathogenesis of carpal tunnel syndrome: microscopic and ultrasound study

This study investigated the connections between the median nerve paraneural sheath and myofascial structures near it, from both macroscopic and microscopic points of view. Four samples of median nerve and surrounding tissues were excised from nine non-embalmed upper limbs for microscopic analysis. Ultrasound images were analysed in 21 healthy subjects and 16 carpal tunnel syndrome patients to evaluate median nerve transversal displacement during finger motion at carpal tunnel and forearm levels. An anatomical continuity between epimysium and paraneural sheath and a reduction of paraneural fat tissue from proximal to distal was found in all samples. Median nerve displacements at both levels were significantly reduced in carpal tunnel syndrome subjects (P < 0.001). It was observed that the median nerve is not an isolated structure but is entirely connected to myofascial structures. Therefore, unbalanced tension of epimysial fasciae can affect the paraneural sheath, limiting nerve displacement, and consequently this must be included in carpal tunnel syndrome pathogenesis.     

The intrinsic arterial vascularity and morphology of the median nerve within the carpal tunnel: a microscopic study

Carpal tunnel syndrome (CTS) is the commonest peripheral nerve entrapment neuropathy and is more prevalent in females for reasons that are not fully understood. The aim of this study was to investigate the intrinsic arterial supply of the median nerve in the region of the carpal tunnel to determine if there are significant individual variations. The median nerve was excised intact from 34 cadaver hands (7 male, 13 female; 18 right, 16 left; age 66–100 years) and sectioned at three levels: 1 cm proximal to the transverse carpal ligament; at the entrance to the carpal tunnel; and 1 cm distal to the latter site. Photomicrographs of histological sections were analyzed using ImageJ and the following recorded: the shape and cross-sectional area (CSA) of the nerve and the total CSA of small arteries/arterioles (>80 μm²) within the nerve. The proportion of the nerve’s CSA occupied by arteries/arterioles was expressed as a ratio to compare vascularity at the three levels. There were no significant differences between hands or levels in males, but in right hands from female cadavers there was a statistically significant reduction in the intrinsic arterial vascularity of the median nerve at the entrance to the carpal tunnel as compared to proximal and distal levels and left hands (p < 0.05). Gender-based differences in the intrinsic arterial supply of the median nerve could be a factor predisposing to CTS.