Median nerve ultrasonography in carpal tunnel syndrome: Findings from two laboratories

Ultrasonographic (US) enlargement of the median nerve at the wrist is known to be consistent with carpal tunnel syndrome (CTS), although the effects of different measurement techniques, equipment, and patient populations remain unknown. The purpose of this study was to examine the similarities and differences of US findings in CTS between two electromyography (EMG) laboratories. In 2006 and 2007, US measurements of the median nerve were recorded independently and statistically analyzed in patients with CTS at two EMG laboratories (Duke University, Durham, NC, USA, and Università Cattolica del Sacro Cuore, Rome, Italy). Patient age, median nerve area in the forearm, and neurophysiologic score did not differ significantly between the two laboratories. The North Carolina group had a larger median nerve area at the wrist and wrist‐to‐forearm ratio than the Italian group, although both were elevated in reference to established values for the diagnosis of CTS. Median nerve US is less susceptible to differences between laboratories than previously thought, permitting greater generalization of findings. Muscle Nerve 40: 94–97, 2009     

Diagnosing carpal tunnel syndrome with Doppler ultrasonography: a comparison of ultrasonographic measurements and electrophysiological severity

Introduction: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy. Diagnosis is based on clinical history, physical examination, and electrophysiological studies. Imaging techniques are performed for difficult-to-diagnose cases because they provide information about the morphology of the median nerve. More recently, it has been shown that Doppler ultrasonography can detect increased intraneural blood flow in CTS. The aim of our study is to evaluate the relationship between the severity of CTS, hypervascularization, and cross-sectional area (CSA) to determine the diagnostic value of Doppler ultrasonography.

Patients and methods: The study group comprised 125 wrists of 75 patients who had been diagnosed with CTS, both clinically and electrophysiologically. The control group comprised 100 wrists of 50 healthy volunteers. Wrists were classified into five stages of CTS severity based on electrophysiologic studies. A radiologist examined the wrists blindly with grayscale images and Doppler ultrasonography to assess CSA and hypervascularization.

Results: A total of 121 wrists were included. There were 28 wrists with minimal CTS severity stage, 36 with mild, 36 with moderate, and 21 with severe. The sensitivity and specificity of CSA and hypervascularization in detecting CTS was 90.9, 94.0, 93.4, and 90.0%, respectively. There was a significant correlation between CTS severity and hypervascularization (p?Conclusion: Our study shows that Doppler ultrasonography results strongly correlate with CTS severity. Hence, this is a useful method for diagnosing CTS and estimating its severity.     

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.     

Muscle intrusion as a potential cause of carpal tunnel syndrome

Introduction: The aim of this study was to determine whether there is an association between flexor digitorum and lumbrical muscle intrusion into the carpal tunnel and carpal tunnel syndrome (CTS). Methods: Five hundred thirteen manual laborers (1026 wrists) were evaluated with ultrasound to determine whether those with CTS had more muscle intrusion into the carpal tunnel than those without CTS. One hundred ninety of the participants without CTS at baseline (363 wrists) were followed over 1 year to determine whether muscle intrusion at baseline predicted the development of CTS. Results: Participants with CTS had more muscle within the carpal tunnel with the wrist in the neutral (P = 0.026) and flexed (P = 0.018) positions than those without CTS. Baseline muscle intrusion did not predict development of CTS at 1 year. Conclusions: Muscle intrusion into the carpal tunnel is associated with CTS, but muscle intrusion alone does not predict the development of CTS over the course of a year. Muscle Nerve 50: 517–522, 2014     

Ultrasonography in severe carpal tunnel syndrome

Introduction: In up to 30% of patients with carpal tunnel syndrome (CTS), the cross‐sectional area (CSA) of the median nerve may not be enlarged. We hypothesize that this could be the result of secondary atrophy of the nerve in severe CTS. The aim of this study was to measure the ultrasonographic CSA of the median nerve at the wrist in patients with severe CTS. Methods: In 14 consecutive patients with clinically and electrophysiologically defined severe CTS, the CSA of the median nerve was measured and compared with that of control subjects. Results: CSA of the median nerve exceeded the upper limit of normal in the majority of patients with severe CTS. Conclusions: Atrophy of the median nerve in severe CTS does not explain negative ultrasonographic test results. Instead, the CSA of the median nerve is enlarged in most patients with severe CTS. Muscle Nerve, 2012     

Neurophysiological classification and sensitivity in 500 carpal tunnel syndrome hands

Objectives - To evaluate the following points about carpal tunnel syndrome (CTS): 1) characterization of a wide population; 2) sensitivity of electrodiagnostic tests, and particularly the contribution of disto-proximal ratio test; 3) validity of a neurophysiological classification developed by us. Material and methods - Prospective study in 500 hands with CTS symptoms. Neurophysiological "standard" tests were always performed: sensory nerve conduction velocity (SNCV) first- and third digit-wrist and distal motor latency (DML). In "standard negative" hands disto-proximal ratio technique (R) was performed. Neurophysiological classification: Extreme CTS (absence of median motor, sensory responses), Severe (absence of sensory response, abnormal DML), Moderate (abnormal SNCV, abnormal DML), Mild (abnormal SNCV, normal DML), Minimal (abnormal R or other segmental/comparative test, normal standard tests). Results- Sensibility of standard tests: 77%. R increased the diagnostic yield by 20%. CTS classification appeared reliable with significant differences between groups. Conclusion - R is a useful test, the classification may be useful in clinical/therapeutical decisions.     

Silent period abnormalities in carpal tunnel syndrome

Cutaneous silent period (CSP) was measured on stimulating digits 2 and 5 in 19 patients with carpal tunnel syndrome (CTS) and compared with 20 healthy volunteers. In 2 patients with severe CTS, CSP was absent on digit 2 but present on digit 5. In mild/moderate CTS digit 2 CSP mean duration was 50.9 ± 13.9 ms, significantly longer than control subjects (36.9 ± 8.7 ms) (P = 0.005). CSP was found to be abnormal in CTS, being absent in severe and prolonged in mild/moderate cases. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:1213–1215, 1998.     

Treatment of carpal tunnel syndrome

Fifty years after its widespread recognition, a significant minority of patients with carpal tunnel syndrome continue to experience poor outcomes from treatment. Much current treatment is supported by an inadequate or nonexistent evidence base. Surgical decompression, often considered the definitive solution, gives excellent results in only 75% of cases in ordinary practice and leaves 8% of patients worse than previously. The only other interventions that are clearly of benefit are neutral-angle wrist splinting, with a success rate of 37%, and steroids, which are better given by local injection than as oral treatment. The initial response rate to injection is 70% but there are frequent relapses. Nevertheless, these conservative treatments have a negligible incidence of serious complications and should be used more widely until surgical failures can be reduced to similar levels.     

Hypercholesterolemia as a risk factor for idiopathic carpal tunnel syndrome

In idiopathic carpal tunnel syndrome (CTS), the median nerve is enlarged within the carpal tunnel due to intraneural connective tissue proliferation. Because hypercholesterolemia, especially increase in low-density lipoprotein (LDL), has been associated with fibrogenesis, we investigated the association of median nerve cross-sectional area and prevalence of idiopathic CTS with serum lipid measurements in middle-aged patients and controls. We found that nerve area and prevalence of CTS were correlated with serum LDL levels. Thus, high LDL levels in middle age are a risk factor for idiopathic CTS, suggesting that the LDL-correlated median nerve enlargement increases the volume of the carpal tunnel contents.     

Sonography in carpal tunnel syndrome

Introduction: Our objective in this study was to assess the diagnostic utility of the median nerve cross‐sectional area (CSA) at the wrist, the wrist–forearm ratio, and the wrist–forearm difference in patients with and without carpal tunnel syndrome (CTS). Methods: Individuals with electrodiagnostically proven CTS and asymptomatic control subjects were recruited prospectively from among patients referred to our electrodiagnostic laboratory. Blinded measurements of CSA were made from transverse sonographic images of the median nerve at the wrist (pisiform) and mid‐forearm. Results: Fifty‐five cases and 49 controls were recruited. Wrist median nerve CSA (15 vs. 9 mm²; P < 0.0001), wrist–forearm ratio (3.09 vs. 1.90 mm²; P < 0.0001), and wrist–forearm difference (10 vs. 4 mm²; P < 0.0001) were all significantly larger in CTS cases (areas under the curve = 0.89, 0.82, and 0.88, respectively). Conclusions: Median nerve CSA at the carpal tunnel inlet and wrist–forearm difference provides the best discrimination between patients with CTS and controls according to receiver operator characteristic (ROC) analysis. Age, gender, height, weight, and wrist size have no effect on CSA. Muscle Nerve, 2011     

Ischaemic sensitivity of axons in carpal tunnel syndrome

Although carpal tunnel syndrome (CTS) is the most common human entrapment neuropathy characterized by paraesthesiae and numbness with nocturnal exacerbation, the mechanisms underlying the generation of these symptoms remain unclear. Consequently, the aim of the present study was to investigate the relationship between changes in axonal excitability and the development of neurological symptoms in response to an ischaemic insult in CTS patients. Sensory and motor excitability were measured in 10 CTS patients and compared with 10 healthy controls, with participants asked to report symptom generation and intensity during the development of limb ischaemia. To induce ischaemia, a sphygmomanometer was inflated above the elbow and maintained at 200 mmHg for 10 min. During ischaemia there were decreases in axonal threshold, with less overall reduction in CTS patients when compared with controls. Associated with these differences in threshold, both sensory (p < 0.001) and motor (p < 0.05) refractoriness increased dramatically in CTS patients. This prominent increase in refractoriness was accompanied by a significant reduction in compound sensory action potentials and compound motor action potentials amplitudes for CTS patients when compared with controls (p < 0.05). These changes in axonal excitability resulted in a higher intensity of numbness and paraesthesiae reported by CTS patients during ischaemia. The present study has established differences in the nerve excitability and symptom development during ischaemia for patients with mild and moderate CTS, and may suggest that axons in the median nerve of CTS patients have an altered functional capacity to respond to an ischaemic insult, further contributing to nocturnal exacerbation of their symptoms.     

Impact of occupational variables in carpal tunnel syndrome

OBJECTIVE: We studied the impact of work-related factors on the outcome in patients operated for carpal tunnel syndrome. METHODS: The population consisted of 106 CTS patients who worked at the time of operation. We registered social and occupational data from the patients. RESULTS: Median time of sick leave was 7 weeks for the total group. Sixty-four percent reported a relationship between their work and the disease. Eighty-nine percent of the operated patients returned to their previous work after operation. CONCLUSIONS: A majority of the patients attributed the CTS-related symptoms to their occupation. Work-related factors may therefore be one possible explanation for the socioeconomical consequences of CTS. A permanent drop-out from work in more than 1 out of 10 patients after CTS treatment indicate that CTS form a substantial socioeconomical burden in the society.     

The carpal tunnel syndrome and amyloidosis. A clinical and histological study

Twenty-six non-randomized patients with carpal tunnel syndrome are presented. It is documented that three out of four patients may be diagnosed pre-operatively by five or more clinical parameters. All patients were screened for amyloidosis in biopsies from the carpal tunnel. One patient presented amyloid deposits in the transversal carpal ligament. The importance of macro- and microscopic findings in the carpal tunnel inclusive local amyloidosis for the pathogenesis of the carpal tunnel is discussed. It is concluded that provided systemic amyloidosis is not suspected, screening for amyloidosis may have diagnostic interest, however without therapeutic consequences and therefore unnecessary.     

Provocation tests in doppler ultrasonography for carpal tunnel syndrome

Introduction: Doppler ultrasonography (DU) has recently been shown to be useful in imaging carpal tunnel syndrome (CTS). In this study, we aim to characterize the changes seen after exercise and electrical stimulation. Methods: Five patients with CTS were recruited with 5 age‐matched subjects. DU was used to visualize the median nerve, flexor tendon, and bone at base line and after 1 minute of: (a) median nerve motor stimulation, (b) median nerve sensory stimulation, (c) abductor pollicis brevis contraction, and (d) adductor digiti minimi contraction. Results: Blood flow in the median nerve was greater after APB exercise. Furthermore, blood flow in the median nerve was greater in cases than controls after APB exercise. At baseline, blood flow in the flexor tendon was greater in cases than controls. Conclusions: While limited by sample size, this study demonstrates that exercise of median innervated muscles may be useful in enhancing diagnostic utility of DU for CTS. Muscle Nerve, 2013     

Bilateral acute carpal tunnel syndrome and hyperthyroidism: a case report

A 26-year-old man acutely developed bilateral sensory symptoms of carpal tunnel syndrome (CTS). Neurophysiological investigations confirmed the diagnosis of CTS with findings suggesting conduction block of sensory fibers. Endocrinological studies revealed a hyperthyroidism. He was treated with methimazole and propranolol with improvement of thyroid function. The neurophysiological and clinical follow-up revealed a progressive improvement of CTS. The echography performed at wrist bilaterally failed to show any rough compressive factors in the carpal tunnel. The clinical, neurophysiological and endocrinological evolution suggest a relationship between hyperthyroidism and acute bilateral CTS.