Occupational and non-occupational risk factors correlating with the severity of clinical manifestations of carpal tunnel syndrome and related work disability among workers who work with a computer

The contribution of certain occupational and personal factors to the development of carpal tunnel syndrome (CTS) is still uncertain. We investigated which specific occupational and non-occupational factors correlate with the level of clinical manifestations and work disability related to CTS. The study included 190 workers who work with a computer and have diagnosed CTS (100 men, 90 women, aged 20-65 years). Subjective experience of CTS-related impairments was assessed with the Symptom Severity Scale (SSS) and the Functional Status Scale (FSS) of the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ). The objective, neural impairments were tested with electrodiagnostics (EDX), whereas CTS-related work disability data were collected from medical records. We found a high inter-correlation between BCTQ, EDX, and work disability data. These also showed high correlations with certain occupational factors (duration of computer-working in months and hours spent daily in computer-working, certain ergonomic, microclimatic, and other occupational conditions) and non-occupational factors (demographic and lifestyle factors: nutritional status, diet, smoking, alcohol consumption, and physical activity). Despite its limitations, our study has identified occupational and non-occupational risk factors that can aggravate CTS and work disability, but which can also be improved with workplace and lifestyle preventive and corrective measures. More research is needed, though, to establish the possible causal relationships and the independent influence of each of those risk factors.

Evaluation of axonal loss in ulnar sensory nerve fibers recorded from ring and little fingers secondary to idiopathic carpal tunnel syndrome in Egyptian patients

Background

The association between carpal tunnel syndrome (CTS) and ulnar nerve entrapment is unclear, and the extra-median paresthesia in the ulnar nerve territory innervation in CTS is unexplained. Our purpose is to evaluate the neurophysiologic changes in ulnar nerve sensory fibers secondary to idiopathic CTS in comparison to normal subjects, and their relation to the severity of CTS.

Results

The difference between CTS and control hands regarding all parameters of ulnar motor nerve conduction studies (MNCS) was not statistically significant (p > 0.05). There was a statistically significant difference in all parameters of median sensory conduction study (SCS) and MNCS between CTS and control hands (p < 0.0001) except for conduction velocity and in all parameters of median and ulnar SCS recording digit 4 (D4) (p < 0.05). The mean value of abnormalities of ulnar SCS recording D4 and digit 5 (D5) was significantly higher in moderate and severe CTS hands (p < 0.05). There were significant negative correlations between median motor and sensory latency and ulnar sensory amplitude recording D4 and D5.

Conclusion

Ulnar sensory nerve abnormalities exist among CTS patients, which were more in moderate and severe grades. The drop in amplitude of ulnar nerve sensory response argues in favor of the possible impact of CTS on the ulnar nerve and did not indicate axonal deterioration of the ulnar nerve.

Are the Sensory Fibers of the Ulnar Nerve Affected in Carpal Tunnel Syndrome?

PURPOSE

Distribution of paresthesia throughout the skin area without median nerve innervation is frequently seen in carpal tunnel syndrome (CTS). However, its pathophysiologic mechanisms are still unclear. We aimed to research whether a dysfunction in sensory fibers of the ulnar nerve (UN) was present or not in hands with CTS.

METHODS

Totally, upper extremity nerve conduction study recordings of 508 patients were considered. After exclusions, 331 upper extremity recordings of 277 patients were included. We compared the results of sensory conduction studies of median nerve and UN between normal hands and hands with CTS.

RESULTS

The mean distal sensory latency of the median nerve was longer, the mean conduction velocity was slower, and mean nerve action potential amplitude was higher in the hands with CTS than in normal hands (P < 0.001 for all comparisons). There was no statistically significant difference on any sensory conduction parameters of UN recorded on digit IV or digit V between the disease and control groups (P > 0.05 for all comparisons). The rates of conduction abnormalities of the UN sensory fibers were also similar in hands with CTS and in normal hands (P > 0.05 for all comparisons).

CONCLUSIONS

The hands with CTS do not have an increased rate of conduction abnormalities of UN sensory fibers compared with the normal hands in our study population. Therefore, our study did not confirm the distortion of UN sensory fibers as a mechanism underlying the spread of paresthesia throughout the skin area without median nerve innervation in CTS.

Vibration thresholds in carpal tunnel syndrome assessed by multiple frequency vibrometry: a case-control study

Background

Carpal tunnel syndrome (CTS) is the most common compression neuropathy, but there is no gold standard for establishing the diagnosis. The ability to feel vibrations in the fingertips is dependent on the function in cutaneous receptors and afferent nerves. Our aim was to investigate vibration perception thresholds (VPTs) in patients with CTS using multi-frequency vibrometry.

Methods

Sixty-six patients (16 men and 50 women) with CTS, diagnosed from clinical signs and by electroneurography, and 66 matched healthy controls were investigated with multi-frequency vibrometry. The VPTs were assessed at seven frequencies (8, 16, 32, 64, 125, 250, and 500 Hz) in the index finger and little finger bilaterally. The severity of the CTS was graded according to Padua and the patient’s subjective symptoms were graded according to the Boston carpal tunnel questionnaire. Touch thresholds were assessed using the Semmes-Weinstein monofilaments.

Results

Patients with CTS had significantly higher VPTs at all frequencies in the index finger and in 6 out of 7 frequencies in the little finger compared to the controls. However, the VPT was not worse in patients with more severe CTS. Patients with unilateral CTS showed significantly higher VPTs in the affected hand. There were no correlations between VPTs and electrophysiological parameters, subjective symptoms, or touch threshold.

Conclusions

Patients with CTS had impaired VPTs at all frequencies compared to the controls. Since the VPTs are dependent on function in peripheral receptors and their afferent nerves, multi-frequency vibrometry could possibly lead to diagnosis of CTS.

Are extramedian symptoms associated with peripheral causes in patient with carpal tunnel syndrome? Electrodiagnostic and ultrasonographic study

OBJECTIVE

To evaluate the relationship between extramedian spreading of sensorial symptoms and median and ulnar nerve cross-sectional area (CSA) and to compare the ultrasonographic and electrophysiological findings in patients with carpal tunnel syndrome (CTS) with or without extramedian sensory symptoms.

DESIGN

Cross-sectional study.

MATERIALS AND METHODS

Patients with CTS were divided into two groups as with or without extramedian symptoms and were assessed clinically, electrophysiologically and ultrasonographically by three blind investigators. In electrophysiological tests, median and ulnar nerve conduction studies were performed. Nerve cross-sectional areas were measured at hook of hamate, psiform bone, radio-ulnar joint, one-third distal part of forearm, and medial epicondyle by ultrasonography.

FINDINGS

The study was completed with 61 patients (108 hands). Extramedian symptoms were present in 31 patients (54 hands). Finger grip strength was lower, pain values evaluated with visual analogue scale were higher in patients with extramedian symptoms (p<0.05). There was no statistically significant difference in electrophysiological and ultrasonographic parameters.

CONCLUSION

According to our results, extramedian symptoms are not related to nerve conduction studies or nerve ultrasonography, these symptoms may be explained with central sensitization in patient with CTS.

Reappraisal of the F/M amplitude ratio in carpal tunnel syndrome

The F-wave/M-wave amplitude (F/M-amp) ratio has been shown to be increased in peripheral neuropathies, provided the maximum M-wave is relatively preserved. Reduced M-wave amplitudes and central facilitation of antidromically-induced reactivation of the anterior horn cells' axon hillocks (F-wave) are believed to contribute to higher F/M-amp ratios. The present study was undertaken to re-evaluate mechanisms responsible for higher F/M-amp ratios in carpal tunnel syndrome (CTS). We enrolled 232 cases affected by CTS and 108 controls. Fand M-wave amplitudes and F-wave chronodispersion were analyzed for the median and ulnar nerves. The F/M-amp ratio of the median nerve in CTS subjects with moderate-severe nerve damage was significantly higher than that of mild CTS subjects and controls. Chronodispersion of the median nerve F-wave increased with increasing CTS severity. We conclude that the relative preservation of the median nerve F-wave is due to damage to the large diameter muscle afferent fibers responsible for the monosynaptic response. Absence of the monosynaptic response makes the small motoneurons, usually inaccessible to the antidromic volley because of its collision with the orthodromic reflex volley, able to fire in the F-wave.

Is the Control of Applied Digital Forces During Natural Five-digit Grasping Affected by Carpal Tunnel Syndrome?

BACKGROUND

The impaired sensory function of the hand induced by carpal tunnel syndrome (CTS) is known to disturb dexterous manipulations. However, force control during daily grasping configuration among the five digits has not been a prominent focus of study. Because grasping is so important to normal function and use of a hand, it is important to understand how sensory changes in CTS affect the digit force of natural grasp.

QUESTIONS/PURPOSES

We therefore examined the altered patterns of digit forces applied during natural five-digit grasping in patients with CTS and compared them with those seen in control subjects without CTS. We hypothesized that the patients with CTS will grasp by applying larger forces with lowered pair correlations and more force variability of the involved digits than the control subjects. Specifically, we asked: (1) Is there a difference between patients with CTS and control subjects in applied force by digits during lift-hold-lower task? (2) Is there a difference in force correlation coefficient of the digit pairs? (3) Are there force variability differences during the holding phase?

METHODS

We evaluated 15 female patients with CTS and 15 control subjects matched for age, gender, and hand dominance. The applied radial forces (Fr) of the five digits were recorded by respective force transducers on a cylinder simulator during the lift-hold-lower task with natural grasping. The movement phases of the task were determined by a video-based motion capture system.

RESULTS

The applied forces of the thumb in patients with CTS (7 ± 0.8 N; 95% CI, 7.2-7.4 N) versus control subjects (5 ± 0.8 N; 95% CI, 5.1-5.3 N) and the index finger in patients with CTS (3 ± 0.3 N; 95% CI, 3.2-3.3 N) versus control subjects (2 ± 0.3 N; 95% CI, 2.2-2.3 N) observed throughout most of the task were larger in the CTS group (p ranges 0.035-0.050 for thumb and 0.016-0.050 for index finger). In addition, the applied force of the middle finger in patients with CTS (1 ± 0.1 N; 95% CI, 1.3-1.4 N) versus the control subjects (2 ± 0.2 N; 95% CI, 1.9-2.0 N) during the lowering phase was larger in CTS group (p ranges 0.039-0.050). The force correlations of the thumb-middle finger observed during the lowering phase in the patients with CTS (0.8 ± 0.2; 95% CI, 0.6-0.9) versus the control subjects (0.9 ± 0.1; 95% CI, 0.8-1.0; p = 0.04) were weaker in the CTS group. The thumb-little finger during holding in the patients with CTS (0.5 ± 0.2; 95% CI, 0.3-0.7) versus the control subjects (0.8 ± 0.2; 95% CI, 0.6-0.9; p = 0.02), and the lowering phase in the patients with CTS (0.6 ± 0.2; 95% CI, 0.3-0.8) versus the control subjects (0.9 ± 0.1; 95% CI, 0.8-1.0; p = 0.01) also were weaker. The force variabilities of patients with CTS were greater in the CTS group than in the control subjects: in the thumb ([0.26 ± 0.11 N, 95% CI, 0.20-0.32 N] versus [0.19 ± 0.06 N; 95% CI, 0.16-0.22 N], p = 0.03); index finger ([0.09 ± 0.07 N; 95% CI, 0.05-0.13 N] versus [0.05 ± 0.03 N; 95% CI, 0.04-0.07 N], p = 0.03); middle finger ([0.06 ± 0.04 N; 95% CI, 0.04-0.08 N] versus [0.03 ± 0.01 N; 95% CI, 0.02-0.04 N], p = 0.02), and ring finger ([0.04 ± 0.03 N; 95% CI, 0.20-0.06 N] versus [0.02 ± 0.01 N; 95% CI, 0.02-0.02 N], p = 0.01).

CONCLUSIONS

Patients with CTS grasped with greater digit force associated with weaker correlation and higher variability on specific digits in different task demands. These altered patterns in daily grasping may lead to secondary problems, which will need to be assessed in future studies with this model to see if they are reversible in patients undergoing carpal tunnel release.

CLINICAL RELEVANCE

The current results helped to identify altered patterns of grasping force during simulated daily function in patients with CTS and to provide the clinician with potential information that might help guide the rehabilitation of grasp in these patients.

Carpal tunnel syndrome and ulnar neuropathy at the wrist: comorbid disease or not?

The aim of this study was to elucidate the possible association between carpal tunnel syndrome (CTS) and ulnar neuropathy at the wrist because of the contradictory results of previous studies. Thus, a retrospective case-control study was arranged with an electromyographic database including patients between 2003 and 2009. Patients were selected according to initial diagnosis and the examiner's criteria, and data were plotted by computer. One thousand nine hundred twenty-four patients were evaluated for CTS and 1,024 patients for diabetic CTS or diabetic polyneuropathy. CTS and ulnar neuropathy co-occurrence and CTS alone at the wrist was found in 54/404, 19/50, 20/27 patients, respectively. Logistic regression analysis revealed that having CTS was associated with a doubled risk of ulnar neuropathy at the wrist in both idiopathic CTS and diabetic CTS groups but not in diabetic polyneuropathy. Being male and of advanced age were other risk factors for ulnar neuropathy at the wrist. Correlation analysis (age and sex were controlled) revealed decreased but significant correlations between median and ulnar sensory amplitudes in CTS cases in all groups.

Vibrotactile sense in patients with diabetes and carpal tunnel syndrome

AIM

To evaluate vibration perception thresholds of patients with and without diabetes, before and after surgical carpal tunnel release.

METHODS

In a prospective study, 35 consecutive patients with diabetes and carpal tunnel syndrome were age and gender matched with 31 patients without diabetes having idiopathic carpal tunnel syndrome. Preoperatively, 6, 12 and 52 weeks after surgery, the vibration perception threshold of the index and little finger (median and ulnar nerve, respectively) was measured at seven different frequencies (8, 16, 32, 64, 125, 250 and 500 Hz).

RESULTS

At several frequencies, patients with diabetes and carpal tunnel syndrome demonstrated significantly impaired vibration perception thresholds of both the index and the little finger, before as well as after carpal tunnel release, compared with patients without diabetes with idiopathic carpal tunnel syndrome. After surgery, the overall sensibility index improved for the index finger [patients with diabetes and carpal tunnel syndrome (0.79 to 0.91, P < 0.001), patients without diabetes with idiopathic carpal tunnel syndrome (0.91 to 0.96, P > 0.05)] as well as for the little finger [patients with diabetes and carpal tunnel syndrome (0.82 to 0.90, P < 0.008), patients without diabetes with idiopathic carpal tunnel syndrome (0.95 to 0.99, P < 0.05)]. For the index finger, the sensibility index improved to a significantly higher degree for patients with diabetes and carpal tunnel syndrome not having signs of peripheral neuropathy (0.83 to 0.95, P < 0.001) compared with those with neuropathy (0.74 to 0.84, P < 0.02). Vibration perception threshold correlates with age of both patients with diabetes and carpal tunnel syndrome and patients without diabetes with idiopathic carpal tunnel syndrome, while no relationship was found based on duration of diabetes.

CONCLUSIONS

Vibrotactile sense is significantly impaired in patients with diabetes before and after carpal tunnel release compared with patients without diabetes. However, patients with diabetes obtained significant recovery of vibration perception threshold, particularly those without peripheral neuropathy.

Neurophysiologic recovery after carpal tunnel release in diabetic patients

OBJECTIVE

To compare nerve conduction study results, before and after surgical carpal tunnel release, in diabetic and non-diabetic patients.

METHODS

In a prospective study (2004-2007), we included 35 consecutive diabetic patients with carpal tunnel syndrome (CTS), who were age and gender matched with 31 non-diabetic patients having idiopathic CTS. Preoperatively, and at the 1 year follow-up, nerve conduction studies were performed of the median and ulnar nerve. Presence of neuropathy was based on abnormal preoperative neurophysiologic values in both the sural and the peroneal nerve.

RESULTS

Diabetic patients demonstrated significantly impaired nerve conduction parameters, before as well as after surgical carpal tunnel release, compared to non-diabetic patients. However, neurophysiologic recovery after carpal tunnel release was not different between the two patient groups or between diabetic patients with or without peripheral neuropathy. In general, the largest neurophysiologic recovery was demonstrated for parameters with the greatest impairment, but normal values were seldom reached.

CONCLUSIONS

Marked neurophysiologic impairment of the median nerve, or signs of peripheral neuropathy, does not preclude significant recovery after carpal tunnel release in diabetic patients.

SIGNIFICANCE

Diabetic patients with CTS should be offered the same opportunities for surgical carpal tunnel release as non-diabetic patients.

EVIDENCE OF IMPROVEMENT IN DISTAL CONDUCTION OF ULNAR NERVE SENSORY FIBERS AFTER CARPAL TUNNEL RELEASE

OBJECTIVE

The aim of this study was to verify any effect of carpal tunnel release (CTR) on distal ulnar nerve conduction findings, using the database of a previous study performed to establish a protocol for CTR outcome.

METHODS

The motor and sensory ulnar distal conduction findings of 251 consecutive hands belonging to 217 patients (175 women and 42 men; mean age, 55.6 years) with idiopathic carpal tunnel syndrome (CTS) were reanalyzed before and 1 and 6 months after CTR.

RESULTS

Before surgery, 115 hands (45.8%) showed reduction of ulnar nerve sensory action potential (SAP) amplitude; this number was reduced significantly to 85 (33.9%) after CTR. The SAP amplitude and sensory conduction velocity values of the ulnar nerve showed significant improvement 1 month after CTR; SAP amplitude values showed further significant improvement 6 months after CTR. Patients' ages and occupations were independent predictors of reduced baseline SAP amplitudes of the ulnar nerve in CTS.

CONCLUSION

These results demonstrate an improvement in conduction values in sensory ulnar fibers in a percentage of patients with CTS after CTR, providing further support for the conclusion that in CTS ulnar fibers may be subject to compressive forces in the Guyon canal as a consequence of high pressure in the carpal tunnel.

Ulnar nerve impairment at the wrist does not contribute to extramedian sensory symptoms in carpal tunnel syndrome

OBJECTIVE

Extramedian spread of sensory symptoms is frequent in carpal tunnel syndrome (CTS) but its mechanisms are unclear. We explored the possible role of subtle ulnar nerve abnormalities in the pathogenesis of extramedian symptoms.

METHODS

We recruited 350 CTS patients. After selection, 143 patients (225 hands) were included. The hand symptoms distribution was graded with a diagram into median (MED) and extramedian (EXTRAMED) pattern. We tested the correlation of ulnar nerve conduction measures with the distribution and the severity of symptoms involving the ulnar territory. The clinical significance of ulnar nerve conduction findings was explored with quantitative sensory testing (QST).

RESULTS

EXTRAMED distribution was found in 38.7% of hands. The ulnar neurographic measures were within normal values. Ulnar nerve sensory measures were significantly better in EXTRAMED vs MED hands and not significantly correlated to ulnar symptoms severity. Ulnar and median nerve sensory measures were significantly correlated. QST showed normal function of ulnar nerve alphabeta-fibers.

CONCLUSIONS

Ulnar nerve sensory abnormalities do not contribute to the spread of sensory symptoms into the ulnar territory.

SIGNIFICANCE

Our data favour the hypothesis that spinal and supraspinal neuroplastic changes may underlie extramedian spread of symptoms in CTS.