Electrodiagnostic evaluation of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common nerve entrapment. Electrodiagnostic (EDX) studies are a valid and reliable means of confirming the diagnosis. This monograph addresses the various EDX techniques used to evaluate the median nerve at the wrist. It also demonstrates the limitations of EDX studies with a focus on the sensitivity and specificity of EDX testing for CTS. The need to use reference values for populations such as diabetics and active workers, where normative values differ from conventional cutoffs used to confirm suspected CTS, is presented. The value of needle electromyography (EMG) is examined.     

Evolution of hand dysfunction and symptoms in untreated carpal tunnel syndrome

The Italian Carpal Tunnel Syndrome (CTS) Study Group assessed the evolution of symptoms and hand dysfunction through validated, patient-oriented measures in 264 patients with 354 hands affected by untreated idiopathic CTS (follow-up 10-15 months). The evolution of symptoms and hand dysfunction was positively related. Only in 3% was there discordance between hand dysfunction and symptom evolution. Thus, in patients with CTS, hand dysfunction and symptoms evolve in parallel.     

The potential value of ultrasonography in the evaluation of carpal tunnel syndrome

The authors compared ultrasonography with electrophysiology for the diagnosis of carpal tunnel syndrome (CTS) on 110 clinically affected wrists. An increased cross sectional area in the proximal carpal tunnel larger than 0.11 cm(2) in combination with compression signs on longitudinal scans proved to be highly predictive for CTS (sensitivity, 89.1%; specificity, 98.0%). Ultrasound was comparable to electrophysiology in the diagnosis of CTS, and in 35% of cases changes in morphology suggested a specific therapeutic strategy.     

Correlation of median forearm conduction velocity with carpal tunnel syndrome severity.

OBJECTIVE: Median nerve entrapment neuropathy at the wrist can be accompanied by slowed motor conduction within the forearm. Existing studies conflict regarding a correlation between the severity of the entrapment neuropathy in carpal tunnel syndrome (CTS) and slowing of median motor nerve conduction velocity (MNCV) in the forearm. Here, it was asked if there is a correlation between markers of CTS severity and median forearm MNCV, and if there is an explanation for the preceding conflicting results. METHODS: Median MNCV in the forearm was correlated with neurophysiologic markers of severity of a median neuropathy at the wrist in 91 hands from 64 patients with clinical and electrodiagnostic evidence of CTS. RESULTS: Median MNCV within the forearm segment was negatively correlated with the median nerve distal motor latency (r=-0.64, P<0.001, n=91) and positively correlated with the CMAP amplitude of the abductor pollicis brevis muscle (r=0.45, P<0.001, n=91). These correlations only occurred in patients with a prolonged median distal motor latency. Previous investigations that failed to find such correlations used variable or non-standardized methods or analyzed smaller numbers of patients. CONCLUSIONS: Slowing of median MNCV in the forearm is related to the severity of the entrapment of median motor fibers at the wrist. SIGNIFICANCE: Slowed forearm median MNCV can be a marker of motor nerve injury at the wrist.     

Sensory distribution indicates severity of median nerve damage in carpal tunnel syndrome.

OBJECTIVE: Sensory symptoms within the median nerve distribution are a primary clinical diagnostic criterion for the diagnosis of carpal tunnel syndrome (CTS). However, the distribution of the sensory symptoms in CTS varies from patient to patient. This study identifies the clinical and electrophysiological findings that correlate with the distribution of sensory symptoms in an Asian population with CTS. METHODS: In a prospective study of 105 patients with electrophysiologically confirmed CTS, clinical and educational data were correlated with sensory symptom distribution. RESULTS: Median nerve distribution was strongly associated with more severe nerve conduction abnormality, male gender, and relief by movement. Patients with a complete median sensory distribution had more electrophysiological abnormality than those with an incomplete median distribution. Extra-median distribution was associated with the least nerve conduction abnormality. Educational qualification, age, symptom duration and body mass index were not associated with the pattern of sensory symptoms. CONCLUSIONS: In carpal tunnel syndrome, sensory symptom distribution is strongly dependant on the degree of electrophysiological median nerve damage. Median nerve sensory distribution is associated with severe nerve damage. SIGNIFICANCE: This study provides clinicians with a simple clinical rule for assigning the degree of median nerve damage in patients with CTS based on sensory distribution patterns.     

Relationships between clinical symptom severity scales and nerve conduction measures in carpal tunnel syndrome

This study examined the severity of symptoms in carpal tunnel syndrome (CTS) in relation to nerve conduction measures of the median nerve. Clinical symptom severity and nerve conduction studies were evaluated for 64 hands with CTS in 45 patients. We found the following: (1) significant relationships identified among the clinical scales resulted in a dichotomous symptom classification scheme into primary and secondary symptoms, with the former being more specific for those symptoms usually seen in association with nerve injury; (2) there were significant relationships between symptom severity and nerve conduction abnormality; (3) the primary symptom scale correlated more strongly with the electrodiagnostic measures of nerve injury than did the secondary symptom scale. Based on these findings, we believe that these clinical scales have biological significance and reflect median nerve injury. This would support their potential utility for evaluating the outcome of CTS treatment and developing a model for exposure-severity relationship.     

Diagnosis of carpal tunnel syndrome: electrodiagnostic and MR imaging evaluation

In clinically classic carpal tunnel syndrome (CTS) without symptoms or signs to suggest other disorders that can mimic CTS, it remains somewhat controversial as to whether performing nerve conduction studies is necessary or cost-effective. MR imaging reliably depicts normal carpal tunnel anatomy. It can also identify pathologic nerve compression and mass lesions, such as ganglion cysts, that compress nerves. Currently, MR imaging is most commonly used to image patients with ambiguous electrodiagnostic studies and clinical examinations. MR diffusion-weighted imaging of peripheral nerves might prove to be the most sensitive imaging sequence for the detection of early nerve dysfunction. Electrodiagnostic studies are likely to remain the pivotal diagnostic examination in patients with suspected CTS for the foreseeable future. With advances in both software and hardware, however, high-resolution MR imaging of peripheral nerves will become faster, cheaper, and likely more accurate, possibly paving the way for an expanded role in the diagnosis of this common syndrome.     

腕管综合征夜间夹板治疗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)评估夜间夹板治疗对腕管综合征(CTS)的疗效,并探讨其间的相关性.方法 自2009年4月至2010年1月武汉大学人民医院神经内科就诊的CTS患者共66例,符合纳入标准者41例(64只腕).对其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)、腕-食指/环指感觉传导速度(SCV)以及正中/尺神经感觉潜伏期差(△DSL).嘱患者以远侧腕皱褶为中心,掌面和背面各一块夹板,入睡前将腕部固定于中立位制动.夹板治疗前、(3.03±1.16)月后分别进行临床评分和NCS.共20例(31只腕)完成随访.结果 (1)DML、腕-食指SCV、腕-环指SCV和△DSL异常率分别为85.9%、78.1%、81.3%和96.9%.(2)与夹板治疗前比较,夹板后SSS和FSS减少、DML缩短、△DSL减小,治疗前、后SSS分别为1.77±0.38、1.55±0.38,FSS为1.53±0.31、1.40±0.27;DML为(4.53±1.25)ms、(4.14±0.76)ms;△DSL为1.24±0.61、0.97±0.60;9例(14只腕)夹板后临床评分无改善.(3)SSS与DML(r=0.420,P=0.019)、腕-食指SCV(r=-0.425,P=0.017)、腕-环指SCV(r=-0.519,P=0.003)之间存在较弱的相关性,与△DSL无相关(r=0.189,P=0.309);FSS与NCS各参数之间均无相关性(P均＞0.05).结论 一半以上CTS患者夹板治疗短期内有效;临床评分与NCS相关性不大,两者共同评估夹板疗效更有意义;△DSL诊断CTS最敏感.     

Utility of the cutaneous silent period in the evaluation of carpal tunnel syndrome

ObjectiveThis study investigates the utility of the cutaneous silent period (CuSP) in evaluating patients with carpal tunnel syndrome (CTS).MethodsThe authors measured the CuSP from the abductor pollicis brevis muscle in 135 hands of patients with idiopathic CTS and 30 hands of age- and gender-matched controls. The patient group was further divided into subgroups according to the Canterbury scale. The differences in parameters between the patient subgroups and control group were analysed. A predetermined analysis looked at the possible correlation between the CuSP and symptom severity as measured by the Boston-Questionnaire.ResultsThe mean CuSP latencies in the patient group (72.4 ± 16.1 ms) was significantly longer than the control group (64.6 ± 13.4 ms; P = 0.014), although there was no difference in the duration of the CuSP between groups. The duration and latency of the CuSP correlated to a higher severity on the Canterbury scale (r = 0.273, P < 0.001 and r = −0.164, P = 0.036, respectively). However, the CuSP parameters did not correlate with the Boston-Questionnaire scores.ConclusionsAlthough patients with CTS had significantly prolonged CuSP latency, the CuSP did not correlate with the clinical symptoms scale.SignificanceThe CuSP is a useful ancillary test to evaluate Aδ fibre function; however, it is not a reliable tool to quantify clinical severity.     

Mutilating hand syndrome in an infant with familial carpal tunnel syndrome

A 7-month-old infant, son of consanguinous Indian parents, presented with recurrent chewing of his digits in a median nerve distribution as the primary manifestation of carpal tunnel syndrome, in conjunction with features consistent with congenital insensitivity to pain. Electromyography (EMG) demonstrated severe median nerve entrapment at the wrist bilaterally, but other nerves were normal. In spite of clinical evidence of diffuse pain insensitivity, sural nerve and skin biopsies were normal, and he had no evidence of autonomic dysfunction. Hand findings evolved with scarring and infection of median innervated digits and loss of fine motor skills. Carpal tunnel release resulted in complete clinical resolution and significant EMG improvement. Milder symptoms and EMG evidence of median nerve entrapment were demonstrated in both parents, paternal grandparents, and several of his father's siblings. We hypothesize this child may be homozygous for a mutant allele that in its heterozygous state predisposes to familial autosomal dominant carpal tunnel syndrome. Homozygosity for this or another mutant allele may be responsible for his congenital insensitivity to pain. © 1998 John Wiley & Sons, Inc. Muscle Nerve, 21: 104–111, 1998.     

Inter-observer reproducibility and responsiveness of a clinical severity scale in surgically treated carpal tunnel syndrome

OBJECTIVES: To test a recently proposed carpal tunnel syndrome (CTS) clinical severity scale for reproducibility between two observers (neurosurgeon and neurophysiologist) before surgery, for responsiveness to changes in clinical status 6 months after surgery, and for correlations with the electrophysiological findings and 'Boston Carpal Tunnel Syndrome Questionnaire' (BQ). MATERIAL AND METHODS: The tests were applied prospectively to a consecutive series of 254 hands with idiopathic CTS, referred for surgical decompression. The hands belonged to 219 subjects (177 women and 42 men, mean age 55.6). RESULTS: Percentage agreement between the two observers in assigning severity to the same class was 78% and Cohen coefficient kappa was 0.69 (P < 0.001). The scale was found to be responsive to changes in clinical status after surgery. Direct correlations were also found between the scale and patient age, duration of symptoms, BQ scores and the neurophysiological severity scale. The significance of these associations was maintained for 6 months after the operation. CONCLUSION: This clinical severity scale is simple, reproducible and sensitive for evaluating severity of CTS in patients undergoing surgery.     

Clinical-electrophysiological correlations in the carpal tunnel syndrome

56 patients with carpal tunnel syndrome (CTS) with 84 hands affected were investigated. All patients were assessed clinically and electromyographically in order to find out whether there is a correlation between clinical signs and/or symptoms and the EMG data. A highly significant correlation was found between sensory deficit (hypoesthesia to touch and/or pain) and the amplitude of SAP and a significant correlation between motor deficits (weakness and/or atrophy) and distal motor latency.

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Sommario Sono stati esaminati 56 pazienti con Sindrome Tunnel Carpale (CTS), per un totale di 84 mani. Ciascun paziente è stato valutato clinicamente ed elettromiograficamente. L'esame clinico mirava ad evidenziare la presenza di deficit sensitivi e motori e rilevare la presenza di altre patologie. Lo scopo del nostro studio è stato quello di valutare l'esistenza di una correlazione tra sintomi e/o segni clinici e dati elettromiografici. È stata rilevata una correlazione particolarmente significantiva tra deficit sensitivo (ipoestesia tattile e/o dolorifica) e ampiezza del SAP e inoltre tra la comparsa di deficit motori (ipostenia) e/o atrofia e la latenza distale motoria.

     

Second lumbrical-interossei nerve test predicts clinical severity and surgical outcome of carpal tunnel syndrome

The purpose of this study was to examine the utility of the second lumbrical-interossei nerve (2L-IN) test in the diagnosis of carpal tunnel syndrome (CTS). We examined 65 patients with suspected unilateral CTS using the 2L–IN test, in addition to the standard electrophysiological test. The operative cases were divided into three classes of severity based on Padua’s neurophysiological classification: extreme CTS (absence of median motor and sensory response); severe CTS (absence of sensory response, abnormal distal motor latency [DML]); and moderate CTS (abnormal sensory nerve conduction velocity, abnormal DML). With the 2L-IN test, the extreme CTS group could be further subdivided into extreme CTS-A (both abductor pollicis brevis [APB]- compound muscle action potential [CMAP] and 2L-CMAP not recordable) and extreme CTS-B (2L-CMAP recordable, APB-CMAP not recordable). Patients with extreme CTS and severe CTS were older, had chronic symptoms, and poorer outcome compared with the moderate CTS patients. Patients of the moderate CTS group were almost all satisfied with the results of surgery. The electrodiagnostic severity correlated with the clinical outcome. Severe strangulation of the thenar muscle branch was identified in patients in the extreme CTS-B group, requiring decompression of the thenar muscle branch rather than conventional simple transverse ligament detachment.     

Grading severity of carpal tunnel syndrome in electrodiagnostic reports: Why grading is recommended

Carpal tunnel syndrome (CTS) is not difficult to confirm by electrodiagnosis (EDx), but the challenge lies in whether to grade the severity and the method for doing so. The arguments about grading are discussed, with an emphasis in favor, using a method that relies on the EDx data, but qualifies that it is the median neuropathy being graded and not the syndrome of CTS. Although use of latencies can be arbitrary and misleading, it is possible to apply other criteria, such as low amplitudes or conduction block and denervation, to develop a grading scale that could be applied widely. Several previously published grading schemes are reviewed, and a new method is described that combines the prior ranking criteria into 3 basic categories. Application of a grading system identifies the degree of nerve injury and thus allows the referring physician to utilize optimally the EDx report to manage the patient. Muscle Nerve 48 : 331–333, 2013     

Optimizing the number of tests for carpal tunnel syndrome

The combined sensory index (CSI), the sum of three latency differences, median-ulnar across the palm (palmdiff), median-ulnar to the ring finger (ringdiff), and median-radial to the thumb (thumbdiff), has higher sensitivity and reliability for carpal tunnel syndrome than individual tests. The objective in this study was to develop an approach that minimizes testing but maximizes accuracy. We retrospectively studied 300 hands. There were endpoints for individual tests that confidently predicted the CSI; for ranges between these endpoints, further testing was required. These ranges were: palmdiff 0-0.3 ms; ringdiff 0.1-0.4 ms; and thumbdiff 0.2-0.7 ms. One may use a strategy in which more tests are performed when results are in these ranges. This approach can allow accurate diagnosis with fewer tests when values are extreme, yet uses the greater diagnostic power of more tests when values are midrange.