Clinical, electrophysiological and magnetic resonance imaging findings in carpal tunnel syndrome

OBJECTIVE: To assess magnetic resonance imaging (MRI) findings in carpal tunnel syndrome (CTS) and to compare them with electrophysiological findings. METHODS: Routine motor and sensory nerve conduction examinations and needle EMG were performed in 42 hands of 22 patients, who were clinically diagnosed as having CTS in at least one wrist. RESULTS: Of 29 wrists with clinically and electrophysiologically confirmed CTS, MRI could detect abnormality in 18 wrists (62%). Median nerve was found to be abnormal in MRI in 1 of 2 wrists with suspected clinical symptoms and proven CTS by electrophysiological examination. MRI was abnormal in 1 of 4 wrists with normal clinical and electrophysiological examination. MRI was abnormal in 46, 7% of wrists with mild CTS, in 61.6% of moderate CTS and in 100% of severe CTS. Volar bulging of the flexor retinaculum was detected in a single wrist with severe CTS. Enlargement of median nerve was observed in 3 of 5 severe CTS. CONCLUSION: MRI could be useful in the diagnosis of unproven cases in CTS. It also provides anatomical information that correlate well with electrophysiological findings in regard of the severity of median nerve compression.     

腕管综合征类固醇腕管局部注射的临床和电生理评估

目的：运用临床评分和神经传导检测（NCS）评估类固醇腕管局部注射对腕管综合征（CTS）的疗效。方法：2009年4月至2010年1月间就诊的CTS患者共66例,符合纳入标准者41例（64只腕）。进行症状严重程度评分（SSS）、功能状态评分（FSS）以及常规NCS,记录腕-拇短展肌末端运动潜伏期（DML）、拇短展肌复合肌肉动作电位（CMAP）波幅,腕-食指／环指感觉传导速度（SCV）、正中／尺神经感觉潜伏期差（△DSL）和感觉神经动作电位（SNAP）波幅。嘱患者改变生活方式且行夜间腕部夹板,2周后症状无好转者行类固醇腕管局部注射。紧挨掌长肌腱尺侧、腕皱褶近侧,用25号针头以30。角朝向腕管进针,注射利多卡因1ml（20mg）和甲基强的松龙1ml（40mg）。注射前、注射（3．23±0．56）个月后分别进行临床评分和NCS。结果：①18例（28只腕）进行了注射,12例（19只腕）完成随访。与注射前比较,注射后SSS和FSS减少、DML缩短、△DSL减小、腕-环指SCV增快、SNAPCMAP波幅增高。注射前、注射后SSS分别为（2．31±0．45）、（1．89±0．46）（t=5．82,P=0．000：FSS为（2．29±0．64）、（1．79±0．59）（t=5．21,P=0．000）;DML（ms）为（5．08±1．58）、（4．66±1．76）（t=2．81,P=0．012）;△DSL（ms）为（1．25±40．67）、（0．93±0．67）（t=3．90,P=0．002）;SCV（m／s）为（40．55±11．48）、（44．70±13．66）（t=-2．55,P=0．029）;SNAP波幅（uV）为（12．72±10．83）、（15．07±11．00）（t=-2．17,P=0．048）;CMAP波幅（mV）为（5．31±3．37）、（6．13±3．04）（t=-2．42,P=0．026）;3例（4只腕、21％）注射后临床评分无改善。②SSS、FSS与NCS各参数之间均无相关性（P均〉0．05）。结论：CTS患者类固醇腕管局部注射治疗至少在短期内有效;临床评分与NCS无相关性,两者共同评估疗效更有意义。     

Characteristics of the electrophysiological activity of muscles attached to the transverse carpal ligament in carpal tunnel syndrome

The main cause of carpal tunnel syndrome (CTS) remains unknown. Stiffness of the subcutaneous area of the volar aspect of the carpal tunnel is present in many patients and suggests that the stiffness of muscles attached to the transverse carpal ligament is increased. We performed an electrophysiological study to investigate muscle activities and to clarify whether the stiffness of muscles attached to the transverse carpal ligament is involved in the pathogenesis of CTS. The subjects of this study included 16 patients with early CTS showing no motor dysfunction. Both thenar muscles (opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis) and hypothenar muscles (opponens digiti minimi, abductor digiti minimi, flexor digiti minimi brevis) were investigated. Surface electrodes were placed on each muscle, and maximum voluntary contractions with the thumb and little finger in opposition were maintained for 3 seconds in all patients and in 7 control subjects. Electromyographs were subjected to fast Fourier transform analysis, and the root mean square (RMS) and the mean power frequency (MPF) were determined for each muscle. The RMS of the opponens pollicis was significantly less in hands affected by CTS (292.8 μV) than in healthy hands (405.9 μV). The RMS did not differ between affected hands and healthy hands for the other 2 thenar muscles but did differ significantly for the hypothenar muscles. The MPF did not differ between affected hands and healthy hands for any muscle. The results show that electrophysiological differences are present among muscles innervated by the median nerve and that hypothenar muscles originally unrelated to median nerve dysfunction are also affected in early CTS. These results suggest that modulation of muscles attached to the transverse carpal ligament is involved in the pathogenesis of CTS.     

Needle electromyography in carpal tunnel syndrome

The role of needle electromyography (EMG) in the routine evaluation of carpal tunnel syndrome (CTS) is not clear. The aim of this study was to determine if needle EMG examination of the thenar muscles could provide useful information in addition to the nerve conduction (NC) studies. Electrophysiologic procedures performed on 84 patients (103 hands) consistent with CTS were reviewed. The median thenar motor NC data were matched with the needle EMG findings in the abductor pollicis brevis (APB) muscle. The severity of the needle EMG findings in the APB muscle correlated well with the severity of the motor NC data. As the thenar compound muscle action potential amplitude decreased and the degree of nerve conduction slowing and block across the wrist increased, there was a corresponding increase in the number of enlarged motor units and decrease in the recruitment pattern in the needle EMG findings. Needle EMG examination confined to the thenar muscles in CTS does not seem to provide any further information when the NC data had already established this diagnosis, and it should not be performed routinely.     

The precision of ultrasound imaging and its relevance for carpal tunnel syndrome

The carpal tunnel syndrome (CTS) is the most common peripheral entrapment neuropathy in human. The diagnosis is based on symptoms and on physical examination and is supported by nerve conduction tests. The aim of this study was to evaluate the precision and the valence of ultrasound (US) for CTS. An anatomic study was performed on 40 wrists of 20 unfixed human cadavers. The carpal tunnel and its important structures and contents were imaged and measured by ultrasound (7.5-MHz high resolution probe). The dorsopalmar diameter (DPD), the radioulnar diameter (RUD), the perimeter (P) and the cross-sectional area (A) were determined for the carpal canal and for the median nerve. These US images and measurements were directly compared with anatomic cross-sections gained from the same wrists at the same level. Our results showed that ultrasound is a very precise method to display the anatomy of the carpal tunnel and of the median nerve and thus the conditions of the median nerve. Significant differences could not be detected for each of these parameters either for the carpal tunnel or the median nerve. (Ultrasound cross-sectional area of carpal tunnel 162.4 ± 29.3 mm² and of the median nerve 9.2 ± 2.4 mm² anatomy cross-sectional area of carpal tunnel 168.4 ± 31.2 mm² and of median nerve 9.4 ± 2.2 mm²).     

Silent period in carpal tunnel syndrome

The silent period is a misunderstood electrophysiological phenomenon leading to several different hypotheses explaining its electrogenesis. It has been studied by different authors and different methodologies giving a wide variability of results, therefore an exact pattern of its normal values does not exist. This work was undertaken to define the normal morphology and duration of the silent period obtained by supramaximal stimulus of the median nerve, during maximum isometric effort of the abductor pollicis brevis muscle against resistance, using 20 adult volunteers without neurological alterations. The normal median duration was 104.6 milliseconds. The same methodology was applied to 20 hands from 20 patients with carpal tunnel syndrome. The silent period showed many types of morphological alterations, but the major alteration observed was a tendency to temporal elongation. No correlation between the severity of the carpal tunnel syndrome and the silent period alterations were observed.     

Autosomal dominant carpal tunnel syndrome

Carpal tunnel syndrome is common in adults and is usually sporadic and idiopathic. When carpal tunnel syndrome is inherited, it is often the manifestation of a systemic disease. We report carpal tunnel syndrome in an otherwise healthy woman aged 35 years. Family history reveals that her daughter, her sister and a sister's daughter, an aunt, a first cousin, her father and the paternal grandmother are also affected. The age of onset of the disease in this family was between 9 and 52 years of age. The family in this paper demonstrates an interesting pattern of inheritance with earlier onset of symptoms in subsequent generations, suggestive of anticipation.     

Collagen dysplasia in idiopathic carpal tunnel syndrome

Surgical biopsies of dissected transverse carpal ligaments of patients with idiopathic carpal tunnel syndrome were examined with an electron microscope revealing collagen fibrils with extremely varying diameters. Morphometric analysis was performed on electron micrographs exhibiting fibrils with a small diameter comparable to that in control tissue as well as fibrils with a far larger diameter than could be observed in control tissue. Morphometric parameters were evaluated in order to analyse the relation between the number of and the area covered by collagen fibrils in the electron micrographs. In control tissue the numerical density per image area was twice the numerical density in carpal tunnel syndrome. However, the area fraction of the electron micrographs occupied by collagen fibrils in carpal tunnel syndrome and controls were equal.     

The cutaneous silent period in carpal tunnel syndrome

OBJECTIVES: The cutaneous silent period (CSP), a sustained voluntary contraction following a painful stimulus applied over the appropriate dermatome produces a brief period of electrical silence, may be useful if the routine nerve conduction studies and needle electromyography are insufficient to diagnose entrapment neuropathies. MATERIAL AND METHODS: To investigate whether symptomatic or asymptomatic patients with entrapment neuropathies are differed in terms of CSP, one hundred fifty four hands of 58 patient and 19 controls were studied according to the clinical and electrophysiological findings. RESULTS: CSP latency and duration could be affected in severe forms of entrapment neuropathies. However, even in patients with dysesthetic pain -which lead to the belief that small fibers may be involved-, results of electrophysiological evaluation could not support the clinical findings. CONCLUSION: In this study it was suggested that CSP studies provide no additional information in entrapment neuropathies.     

Age and the severity of carpal tunnel syndrome

Several studies have shown an increased incidence of Carpal Tunnel Syndrome (CTS) with increasing age, as well as a longer Median sensory latency in older CTS patients. In this study, data was analyzed from 19 patients with bilaterally normal UE EMG/NCS and no symptoms of CTS (38 hands), as well as 18 patients with unilateral CTS and 21 with bilateral CTS (60 hands) to determine the effect of age on the severity of nerve conduction abnormalities associated with CTS. Most of these parameters showed increasing severity with age. Median motor latency rises sharply with age (r = .41, p = .001), and amplitude falls (r = .34, p = .008). Median sensory rises significantly with age in CTS patients (r = .42, p = .001) and amplitude falls (r = .29, p = .022). Furthermore, the (Median-Ulnar) motor and sensory latency differences both rise with age (r = .40, p = .001, and r = .35, p = .004 respectively). This is crucial, for an increase in Median motor or sensory latency with age could represent a similar degree of pathologic slowing superimposed on normally slower conduction with age. However, the sharp rise in the (Median-Ulnar) latency differences (from 2.2 msecs at age 40 to 3.8 msecs at age 70 for motor, and 1.6 msecs to 2.5 msecs for sensory) shows that the compression is more severe with age.     

腕管综合征患者的临床与神经电生理研究

目的：观察神经电生理检测对腕管综合征(CTS)的诊断价值。方法：对腕管综合征的临床特征及病因进行了分析，并作神经传导速度(NCV)和肌电图检测和分析。结果：40条患病神经中8条正中神经诱发波形消失，32条正中神经感觉潜伏期延长、波幅降低或(和)感觉神经传导速度减慢。25例患者伴有30条正中神经运动末梢潜伏期延长或(和)动作电位波幅降低。22块正中神经支配肌有去神经电位。结论：神经电生理检查在腕管综合征的诊断与鉴别诊断中有重要意义。