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.     

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.     

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.

---

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.     

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.     

Electromyographic diagnosis of the carpal tunnel syndrome

Sensory conduction velocities of the median nerve were studied from digit to palm and from palm to wrist in normal subjects and in patients with the carpal tunnel syndrome. Definite slowing was noted in the palm to wrist segment, even in the early carpal tunnel syndrome. It was noted that 37% of normal women over 40 years of age had electrophysiological evidence of the carpal tunnel syndrome.     

Lack of hyperlipidemia in carpal tunnel syndrome

115 females with a definitive diagnosis of a carpal tunnel syndrome (CTS) are compared with a corresponding age-matched group of healthy females with regard to their lipidemic parameters. The incidence of hyperlipoproteinemias in CTS patients was equal to that in the control group so that hyperlipoproteinemia is unlikely to be a probable cause of the entrapment syndrome. A statistically significant increase in the level of alpha-lipoprotein (high-density lipoprotein) was found which cannot be readily explained.     

Terminal latency index in the carpal tunnel syndrome

Our retrospective study assessed the validity of the median motor terminal latency index (m-TLI) in evaluation of carpal tunnel syndrome (CTS). In patients deemed most likely to have CTS, the mean m-TLI was markedly reduced at 0.25 while the controls had a mean m-TLI of 0.44. The m-TLI was abnormal in all of the “probable CTS” hands and in none of the control hands. The m-TLI is a sensitive adjunctive electrophysiologic measure for the presence of CTS. © 1997 John Wiley & Sons, Inc. Muscle Nerve 20:1178–1180, 1997