The Electrodiagnostic Approach to Carpal Tunnel Syndrome

Mapping Neurophysiological Patterns in Carpal Tunnel Syndrome: Correlations With Tinel's and Phalen's Signs

Background This study aimed to observe the neurophysiological severity grading of carpel tunnel syndrome (CTS) using nerve conduction studies (NCSs) and the correlation between Tinel's and Phalen's signs. Methodology In this cross-sectional study, 240 patients of CTS were enrolled. NCSs were conducted in 480 hands. Various variables such as distal latency, amplitude, and nerve conduction velocity in both sensory and motor median nerves were recorded. The provocative tests capable of reproducing patients' symptoms such as Phalen's test and Tinel's test were performed on all 480 hands studied. Results Neurophysiological variables were affected in 449 out of 480 hands. Tinel's sign was observed in 59% of cases (265 hands) while Phalen's sign was positive in 37.2% (167 hands) of cases. Severity grading of CTS based on neurophysiological variables resulted in Grade I (mild) in 202 hands, Grade II (mild to moderate) in 56 hands, Grade III (moderate) in 39 hands, and Grade IV (severe) in 152 hands. Provocative tests (Tinel's and Phalen's) used for the diagnosis of CTS were positive in 68 hands (36.66%) and 26 hands (12.8%), respectively, in mild Grade I. However, as the CTS severity grade increased, the provocative test success rate also increased simultaneously. In severe Grade IV CTS, Tinel's and Phalen's tests were positive in 134 (88.1%) hands and 94 (61.8%) hands, respectively. Conclusions This study underscores the unreliability of Tinel's and Phalen's signs as screening methods for CTS severity. With moderate sensitivity and specificity, NCSs are deemed essential for confirming CTS diagnosis and assessing severity, especially in mild cases that might be mistakenly perceived as normal hands by consultants.

How to Differentiate Pronator Syndrome from Carpal Tunnel Syndrome: A Comprehensive Clinical Comparison

The diagnostic process that allows pronator syndrome to be differentiated reliably from carpal tunnel syndrome remains a challenge for clinicians, as evidenced by the most common cause of pronator syndrome misdiagnosis: carpal tunnel syndrome. Pronator syndrome can be caused by compression of the median nerve as it passes through the anatomical structures of the forearm, while carpal tunnel syndrome refers to one particular topographic area within which compression occurs, the carpal tunnel. The present narrative review is a complex clinical comparison of the two syndromes with their anatomical backgrounds involving topographical relationships, morphology, clinical picture, differential diagnosis, and therapeutic options. It discusses the most frequently used diagnostic techniques and their correct interpretations. Its main goal is to provide an up-to-date picture of the current understanding of the disease processes and their etiologies, to establish an appropriate diagnosis, and introduce relevant treatment benefiting the patient.

Occupational hand and wrist disorders among forestry workers: An exposed-control study to investigate preventive strategies

BACKGROUND: In the arboriculture sector, some activities are still manually performed by forestry workers, which result consequently exposed to a high risk of developing muscle skeletal disorders. The Italian Compensation Authority reported an increase of work-related tendinopathies and carpal tunnel syndrome in loggers, but screening protocols are not available yet. OBJECTIVES: The objectives were: a) to evaluate the prevalence of tendinopathies and carpal tunnel syndrome in a sample of loggers and b) identify a sound screening approach. METHODS: 41 loggers and 41 paired control workers were recruited for a total of 164 hands. The protocol included 1) demographic data; 2) medical history; 3) identification of CTS symptoms through a questionnaire and a hand-chart; 4) upper limbs clinical examination; 5) Raynaud’s diseases questionnaire; 6) wrists ultrasound; 7) NCS of the distal median nerve. RESULTS: The prevalence of tendinopathies was statistically significant only in the non-dominant hand (75, 5% in the exposed group and 53, 6% in the non-exposed group). The prevalence of CTS was 32, 2% in the exposed group and 15, 5% in the non-exposed group. The questionnaire had a sensitivity of 56, 7% and a specificity of 75%. The hand-chart had a sensitivity of 30% and a specificity of 92%. The clinical examination had sensitivity of 30% and specificity of 80%. The ultrasound had a sensitivity of 70% and a specificity of 56%. CONCLUSIONS: Loggers are a population at risk of occupational hand and wrist disorders. The hand-chart could be considered, together with the questionnaire, as the best secondary prevention tool to diagnose CTS.

Ultrasound of Median Nerve in the Diagnosis of Carpal Tunnel Syndrome—Correlation with Electrophysiological Studies

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy caused by impairment of the median nerve due to compression as it passes through the carpal tunnel.

The current gold standard in diagnosing CTS and nerve damage is by electrophysiological nerve conduction study (NCS). However, 10 to 25% of NCS results are falsely negative. Moreover, NCS remains an expensive and time-consuming procedure for patients. Ultrasonography serves as a real-time, well-tolerated, portable, and noninvasive tool for assessing the carpal tunnel.

This study aims to assess the role of high-frequency ultrasound of the median nerve at the wrist in evaluating CTS and correlate with NCS to determine whether sonography can be used as an alternative to NCS in diagnosing and grading CTS.

Evaluation of the Existing Electrophysiological Severity Classifications in Carpal Tunnel Syndrome

Electrophysiological examination is important for the diagnosis and evaluation of nerve function in carpal tunnel syndrome (CTS). Electrophysiological severity classifications of CTS using a nerve conduction study (NCS) have been reported, and there are many reports on the relationship between severity classifications and clinical symptoms. The existing electrophysiological severity classifications have several problems, such as cases that do not fit into a classification and unclear reasons for the boundary value. The purpose of this study was to clarify the relationship between sensory nerve conduction velocity (SCV) and distal motor latency (DML) and to evaluate whether the existing severity classification method is appropriate. We created a scatter diagram between SCV and DML for our NCSs and found a negative correlation between SCV and DML (correlation coefficient, −0.786). When we applied our NCSs to the existing classifications (Padua and Bland classifications), there were many unclassifiable cases (15.2%; Padua classification), and the number of Grade 3 cases was significantly higher than that of Grade 2 or 4 cases (Bland classification). Our large dataset revealed a strong negative correlation between SCV and DML, indicating that the existing severity classifications do not always accurately reflect the severity of the disease.

Revision of Carpal Tunnel Surgery

Carpal tunnel release is one of the most commonly performed upper extremity procedures. The majority of patients experience significant improvement or resolution of their symptoms. However, a small but important subset of patients will experience the failure of their initial surgery. These patients can be grouped into persistent, recurrent, and new symptom categories. The approach to these patients starts with a thorough clinical examination and is supplemented with electrodiagnostic studies. The step-wise surgical management of revision carpal tunnel surgery consists of the proximal exploration of the median nerve, Guyon’s release with neurolysis, the rerelease of the transverse retinaculum, evaluation of the nerve injury, treatment of secondary sites of compression, and potential ancillary procedures. The approach and management of failed carpal tunnel release are reviewed in this article.

The Association Between Electrodiagnostic Severity and Treatment Recommendations for Carpal Tunnel Syndrome

PURPOSE

Our study aimed to evaluate the relationship between electrodiagnostic study (EDS) severity and utilization of treatments for carpal tunnel syndrome (CTS) as well as the duration of time between EDS and carpal tunnel release (CTR).

METHODS

We conducted a retrospective medical chart review at a single tertiary hand center to evaluate CTS-related care that patients received after EDS. We recorded patient age, sex, race/ethnicity, insurance type, CTS-related surgical and nonsurgical healthcare utilization after EDS testing, and number of days between EDS and CTR.

RESULTS

Among all patients with an eventual diagnosis of CTS who received EDS (n = 210), nearly half had normal or mild severity (23%, n = 48; and 28%, n = 58, respectively) and the other half had moderate or severe EDS findings (26%, n = 55; and 23%, n = 49, respectively). Patients with severe findings had the highest rate of receiving surgery (53%) compared with patients with mild and moderate findings (33% vs 46%, respectively). Among the patients who received CTR (n = 73), patients with severe EDS findings had the shortest time to CTR (59.5 days; interquartile range [IQR], 30-81), compared with mild severity (170 days; IQR, 87-415) and moderate severity (77 day; IQR, 42-292). Moderate and severe EDS findings were associated with significantly higher odds of receiving CTR in adjusted analyses (odds ratio, 2.48, 95% confidence interval, 1.04-5.93 and odds ratio 3.79, 95% confidence interval, 1.51-9.50, respectively) compared with patients with mild EDS findings. However, the odds of receiving steroid injection and hand therapy/orthosis were not significantly different based on severity.

CONCLUSIONS

Electrodiagnostic study severity had a direct relationship to the probability of receiving surgery but did not correlate with use of nonsurgical treatment. The study findings signal a need to evaluate the value of nonsurgical treatments in patients with severe EDS findings.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

Clinical and electrophysiological evaluation of carpal tunnel syndrome: approach and pitfalls

One of the most common referrals to the electrodiagnostic (EDX) laboratory is to confirm a clinical impression of carpal tunnel syndrome (CTS). The EDX studies are valuable in localizing median nerve abnormalities to the wrist, grading its severity, and excluding other condition that can mimic or coexist with CTS. However, there are many clinical and EDX pitfalls that can lead to misdiagnosis. Careful clinical assessment and attention to technical factors and details of the EDX techniques are fundamental for the quality and accurate interpretation of the study. This review aims to discuss the clinical and the EDX approaches to the diagnosis of CTS with emphasis on the commonly encountered pitfalls.

Body mass index and vitamin D level in carpal tunnel syndrome patients

Background

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper extremity. The aim of this study is to evaluate the body mass index (BMI) and vitamin D levels in CTS patients.

Methods

The current study was conducted at Zagazig University Hospitals. It included 50 CTS patients and 50 controls. Clinical assessment was carried out to exclude symptoms and signs of neuropathy. Laboratory investigations including vitamin D levels, glycosylated hemoglobin, liver, and kidney function were carried out for every participant. All patients underwent electrodiagnostic study and completed Boston questionnaire to assess their pain sum score, symptom severity (SSS), and functional status (FSS).

Results

Patients had significantly higher BMI and lower vitamin D levels compared to controls (p = 0.003 and p = 0.001, respectively). Those with severe CTS had a significantly higher BMI and lower vitamin D levels than the others (p = 0.03 and p = 0.01 respectively). No significant difference was found between CTS subgroups regarding the SSS, while a higher significant FSS and pain sum score were reported in the severe CTS patients compared to the other two groups (p = 0.01 and p = 0.04 respectively). A significant negative correlation was detected between vitamin D levels and both of BMI, and Boston pain sum scores (p = 0.01 and p = 0.03 respectively). Also, an inverse correlation was detected between vitamin D levels and both of SSS and FSS (p = 0.14, p = 0.06). Furthermore, a significant positive and negative correlation between vitamin D levels and both of conduction velocity and distal motor latency respectively was observed (p = 0.02 and p = 0.01 respectively).

Conclusions

Carpal tunnel syndrome was significantly associated with hypovitaminosis D especially in patients with higher BMI. This highlights the importance of vitamin D supplements and weight loss regimes to minimize the severity of their pain.

Evaluation of thenar muscles by MRI in carpal tunnel syndrome

In the present study, the thenar muscles were evaluated using magnetic resonance imaging (MRI), in addition, the correlations between thenar muscle changes, clinical findings and electrodiagnostic results from patients with carpal tunnel syndrome were investigated. The subjects were 13 patients (17 wrists) who were clinically diagnosed with carpal tunnel syndrome. In all patients, a medical history was obtained and physical examination was performed, in addition to assessment using the Kapandji scoring system, visual analogue scale (VAS), quick-disabilities of the arm, shoulder and hand (Q-DASH) score, electrodiagnostic results of the median nerve, and MRI of the thenar muscles. Thenar muscle volume was not significantly correlated with clinical data or the electrodiagnostic results. The thenar muscle major axis was significantly correlated with grasp power (P<0.05) and the Kapandji score (P<0.05), while the thenar muscle minor axis was significantly correlated with abductor pollicis brevis distal motor latency (APB DML) (P<0.01). In addition, the thenar muscle minor axis/thenar muscle major axis ratio was significantly correlated with APB DML and Kanatani's stage. Notably, thenar muscle thinness was significantly correlated with the severity of electrodiagnostic changes, while the grasp power and Kapandji score were correlated with thenar muscle thickness. Furthermore, it was demonstrated that thenar muscle thinness was significantly correlated with the severity of electrodiagnostic changes; in addition, there was a significant correlation between the thenar muscle major axis and the grasp power or Kapandji score. Taken together, these results revealed that thenar muscle atrophy did not affect patient-based assessments, including VAS and Q-DASH, but reflected electrodiagnostic results, particularly DML and severity. The results of the present study suggest that thenar muscle atrophy can be used to estimate the severity of carpal tunnel syndrome.

Facilitatory and inhibitory pain mechanisms are altered in patients with carpal tunnel syndrome

Preliminary evidence from studies using quantitative sensory testing suggests the presence of central mechanisms in patients with carpal tunnel syndrome (CTS) as apparent by widespread hyperalgesia. Hallmarks of central mechanisms after nerve injuries include nociceptive facilitation and reduced endogenous pain inhibition. Methods to study nociceptive facilitation in CTS so far have been limited to quantitative sensory testing and the integrity of endogenous inhibition remains unexamined. The aim of this study was therefore to investigate changes in facilitatory and inhibitory processing in patients with CTS by studying hypersensitivity following experimentally induced pain (facilitatory mechanisms) and the efficacy of conditioned pain modulation (CPM, inhibitory mechanisms). Twenty-five patients with mild to moderate CTS and 25 age and sex matched control participants without CTS were recruited. Increased pain facilitation was evaluated via injection of hypertonic saline into the upper trapezius. Altered pain inhibition through CPM was investigated through cold water immersion of the foot as the conditioning stimulus and pressure pain threshold over the thenar and hypothenar eminence bilaterally as the test stimulus. The results demonstrated that patients with CTS showed a greater duration (p = 0.047), intensity (p = 0.044) and area (p = 0.012) of pain in response to experimentally induced pain in the upper trapezius and impaired CPM compared to the control participants (p = 0.006). Although typically considered to be driven by peripheral mechanisms, these findings indicate that CTS demonstrates characteristics of altered central processing with increased pain facilitation and reduced endogenous pain inhibition.

Comparative study between physical examination, electroneuromyography and ultrasonography in diagnosing carpal tunnel syndrome

OBJECTIVE

To evaluate the sensitivity of electromyography and ultrasonography in diagnosing carpal tunnel syndrome (CTS), in comparison with physical examination, which is considered to be the gold standard.

METHODS

In this cross-sectional study, the medical files of 56 patients with 70 hands affected by CTS who were attended between March 2010 and June 2012 were reviewed. The study included patients with a clinical diagnosis of CTS. The sensitivity of the complementary examinations was analyzed and compared with physical examination.

RESULTS

Nocturnal symptoms were found in 96.4%, thenar atrophy in 62.5% and abnormal sense of touch in 50%. The sensitivities found were: ultrasonography, 67.1% (95% CI: 55.7%-78.6%); an association of physical examination tests, 95.7% (95% CI: 90.0%-100%); and electromyography, 98.6% (95% CI: 95.7%-100%). The presence of atrophy, abnormalities of the sense of touch and longer-duration symptoms increased the sensitivity of ultrasonography and physical examination.

CONCLUSION

The sensitivity of ultrasonography for CTS was lower than that of electromyography and physical examination.

Changes in treatment plan for carpal tunnel syndrome based on electrodiagnostic test results

This study evaluated how often the treatment plan for carpal tunnel syndrome (CTS) changed based on electrodiagnostic test results. Secondly, we assessed factors associated with a change in the treatment plan for CTS. One-hundred-and-thirty English-speaking adult patients underwent electrodiagnostic testing in a prospective cohort study. Treatment plan was recorded before and after testing. Treatment plan changed in 25 patients (19%) based on electrodiagnostic test results. The plan for operative treatment before testing decreased significantly after testing (83% versus 72%). The best logistic regression model for no change in treatment plan included a prolonged or non-recordable median distal sensory latency (normal, prolonged, or non-recordable), and explained 24% of the variation. For surgeons that manage CTS on the basis of objective pathophysiology rather than symptoms, electrodiagnostic test results often lead to changes in recommended treatment.

Colchicine treatment in children with familial Mediterranean fever: is it a risk factor for neuromyopathy?

BACKGROUND

We cared for a 17-year-old adolescent with familial Mediterranean fever under colchicine treatment. Because of the increased creatinine kinase level (3937 U/L) observed in this individual, we planned to assess all pediatric patients with familial Mediterranean fever under colchicine treatment to detect any resultant neuromyopathy.

METHODS

The study included 88 children with familial Mediterranean fever who were receiving colchicine. The patient with myopathy was not included in the study. Serum creatinine kinase levels were measured and nerve conduction studies were carried out in all patients.

RESULTS

The study included 88 patients (47 female, 53.4%) with an average age of 10.1 ± 3.35 years. The average period of colchicine use was 28.25 ± 17.66 months. Side effects of colchicine were detected in 10 patients (11%)--as diarrhea in eight patients, leukopenia in one patient, and hair loss in one patient. Nerve conduction studies determined incidental carpal tunnel syndrome in only one patient.

CONCLUSIONS

Our study did not suggest an elevated risk of neuromyopathy associated with the use of colchicine for familial Mediterranean fever.

High-resolution median nerve sonographic measurements: correlations with median nerve conduction studies in healthy adults

OBJECTIVES

To study relationships between median wrist and forearm sonographic measurements and median nerve conduction studies.

METHODS

The study population consisted of a prospective convenience sample of healthy adults. Interventions included high-resolution median nerve sonography and median motor and sensory nerve conduction studies. Main outcome measures included median motor nerve compound muscle action potential amplitude, distal latency, and conduction velocity; sensory nerve action potential amplitude and distal latency; and sonographic median nerve cross-sectional area. Median motor nerve and sensory nerve conduction studies of the index finger were performed using standard published techniques. A second examiner blinded to nerve conduction study results used a high-frequency linear array transducer to measure the cross-sectional area of the median nerve at the distal volar wrist crease (carpal tunnel inlet) and forearm (4 cm proximally), measured in the transverse plane on static sonograms. The outer margin of the median nerve was traced at the junction of the hypoechoic fascicles and adjacent outer connective tissue layer.

RESULTS

Fifty median nerves were evaluated in 25 participants. The compound muscle action potential amplitude with wrist stimulation was positively related to the cross-sectional area, with the area increasing by 0.195 mm(2) for every millivolt increase in amplitude in the dominant hand (95% confidence interval, 0.020, 0.370 mm(2); P < .05) and 0.247 mm(2) in the nondominant hand (95% confidence interval, 0.035, 0.459 mm(2); P < .05). There was no significant linear association between the wrist median cross-sectional area and median motor and sensory distal latencies. Conduction velocity through the forearm was not significantly linearly associated with the forearm area or forearm-to-wrist area ratio (tapering ratio). The wrist area was inversely related to the sensory nerve action potential amplitude.

CONCLUSIONS

Although associations were found between median nerve conduction study amplitudes and sonographic nerve measurements, they were not found for other parameters. Studying these relationships may increase our understanding of when to best use these procedures.

Timing and appropriate use of electrodiagnostic studies

Electrodiagnostic studies are powerful tools used to objectively examine the physiologic status of a nerve. These consist of nerve conduction studies, which directly examine motor and sensory function of the nerve, and electromyography, which examines spontaneous and voluntary motor unit action potentials in the muscle. Together these studies enable characterization, localization, and duration of nerve pathology. Appropriate timing and use of electrodiagnostic studies assist medical providers in treating nerve pathology.

An open-label pilot study evaluating the effectiveness of the heated lidocaine/tetracaine patch for the treatment of pain associated with carpal tunnel syndrome

OBJECTIVES

Carpal tunnel syndrome (CTS) is a common entrapment neuropathy of the median nerve at the wrist that is characterized by pain, paresthesias, weakness, and loss of dexterity. This pilot study was conducted to evaluate the heated lidocaine/tetracaine patch (HLT patch) as a conservative treatment for pain of CTS.

METHODS

Twenty adult patients (mean age = 44 ± 12 years) with pain secondary to unilateral CTS and electrodiagnostic evidence of mild-to-moderate CTS enrolled in this open-label study. Patients were treated with a single HLT patch placed over the junction of forearm and wrist on the palmar aspect of the wrist twice daily (morning and evening at 12-hour intervals) for 2 hours. At baseline and during the 2-week study, patients graded their pain intensity with an 11-point numerical rating scale (0 = no pain, 10 = worst imaginable pain). Pain interference with general activity, work, and sleep was evaluated with a similar 0-to-10-point scale.

RESULTS

Fifteen patients completed the 14-day treatment period. Mean average pain intensity score decreased from 5.1 ± 1.5 at baseline to 2.5 ± 1.6 at end of study in the per-protocol population (P < 0.001). Two-thirds of the patients demonstrated clinically meaningful pain relief (≥ 30% reduction in average pain score), with 40% of the patients reaching this threshold by the third treatment day. Similar improvements were observed for pain interference scores. The HLT patch was generally well tolerated.

CONCLUSION

The HLT patch resulted in clinically meaningful reduction in pain intensity in the majority of patients with mild-to-moderate CTS and may represent a targeted nonsurgical treatment for pain associated with CTS.