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

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.

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.

The clinical relevance of complex regional pain syndrome type I: The Emperor's New Clothes

The management of patients with chronic pain is a nearly daily challenge to rheumatologists, neurologists, orthopedic surgeons, pain specialists and indeed a issue in nearly every clinical practice. Among the myriad of causes of pain are often included a unique syndrome, generally referred to as complex regional pain syndrome type I (CRPS). Unfortunately CRPS I has become a catch all phase and there are serious questions on whether it exists at all; this has led to an extraordinary number of poorly defined diagnostic criteria. It has also led to an etiologic quagmire that includes features as diverse as autoimmunity to simple trauma. These, in turn, have led to overdiagnosis and often overzealous use of pain medications, including narcotics. In a previous paper, we raised the issue of whether CRPS type I reflected a valid diagnosis. Indeed, the diagnostic criteria for CRPS I, and therefore the diagnosis itself, is unreliable for a number of reasons: 1) the underlying pathophysiology of the signs and symptoms of CPRS I are not biologically plausible; 2) there are no consistent laboratory or imaging testing available; 3) the signs and symptoms fluctuate over time without a medical explanation; 4) the definitions of most studies are derived from statistical analysis with little consideration to required sample size, i.e. power calculations; 5) interobserver reliability in the assessment of the signs and symptoms are often only fair to moderate, and agreement on the diagnosis of "CRPS I" is poor. Even physicians who still believe in the concept of "CRPS I" admit that it is vastly overdiagnosed and has become a diagnosis of last resort, often without a complete differential diagnosis and an alternative explanation. Finally, one of the most convincing arguments that there is no clinical entity as "CRPS I" comes from the enormous heterogeneity in sign and symptom profiles and the heterogeneity of pathophysiological mechanisms postulated. This observation is underscored by the diversity of responses among "CRPS I" patients to essentially all treatment modalities. It has even led to the concept that the signs and symptoms of CRPS can spread throughout the body, as if it is an infectious disease, without any medical plausible explanation. If true progress is to be made in helping patients with pain, it will require entirely new and different concepts and abandoning CRPS I as a legitimate diagnosis.

Sonographic findings in the ulnar nerve according to the electrophysiologic stage of carpal tunnel syndrome

OBJECTIVES

Involvement of the ulnar nerve in patients with carpal tunnel syndrome is controversial. The aim of our study was to evaluate sonographic findings in the ulnar nerve in patients with carpal tunnel syndrome.

METHODS

We performed median and ulnar nerve conduction studies with sonography in 109 hands of 60 patients with clinically suspected carpal tunnel syndrome. Sonographic findings were analyzed with regard to electrophysiologic stages of carpal tunnel syndrome.

RESULTS

We found that the sensory conduction velocity of the ulnar nerve decreased as the electrophysiologic stage of carpal tunnel syndrome increased (P = .038), but there was no change in the cross-sectional area of the ulnar nerve at the wrist. The median-to-ulnar nerve cross-sectional area ratio at the wrist showed a significant correlation with the electrophysiologic stage of carpal tunnel syndrome (Spearman r = 0.431; P < .0001), in addition to the median nerve cross-sectional area at the wrist and the wrist-to- forearm median nerve cross-sectional area ratio.

CONCLUSIONS

In our study, ulnar nerve involvement in patients with carpal tunnel syndrome was shown electrophysiologically but not sonographically. These results suggest that morphologic changes in the ulnar nerve do not occur in carpal tunnel syndrome, although functional changes may occur.

Does measuring the median nerve at the carpal tunnel outlet improve ultrasound CTS diagnosis?

INTRODUCTION

Nerve conduction is often regarded as more sensitive than ultrasonography (US) for diagnosing carpal tunnel syndrome (CTS). The diagnostic value of US derives from median nerve enlargement occurring at both ends of the carpal tunnel resulting in a dumbbell-like swelling from carpal tunnel pressure. An important reason for the inferior sensitivity of US may be because measurements are restricted to the carpal tunnel inlet. We investigate the value of including median nerve enlargement at the carpal tunnel outlet for diagnosing CTS.

METHODS

Retrospective cohort study of nerve conduction verified CTS, determining sensitivity, specificity, and positive and negative predictive values of carpal tunnel inlet and outlet median nerve cross sectional area as determined by US for the diagnosis of CTS. Nerve conduction graded CTS severity.

RESULTS

127 hands from 77 patients with CTS and 35 control healthy hands were assessed. US sensitivity for diagnosing CTS increased from 65% to 84% by including outlet enlargement of the median nerve. Specificity changed from 94% to 86%, positive predictive value from 98% to 96% and the negative predictive value from 43% to 60%. 25 hands out of the 127 from CTS patients showed enlargement restricted to the outlet and mainly occurred in moderate CTS.

CONCLUSION

In our population, the use of carpal tunnel outlet median nerve enlargement in addition to inlet median nerve size increases sensitivity for diagnosing CTS by 19%.

Symptoms, signs and nerve conduction velocities in patients with suspected carpal tunnel syndrome

BACKGROUND

To inform the clinical management of patients with suspected carpal tunnel syndrome (CTS) and case definition for CTS in epidemiological research, we explored the relation of symptoms and signs to sensory nerve conduction (SNC) measurements.

METHODS

Patients aged 20-64 years who were referred to a neurophysiology service for investigation of suspected CTS, completed a symptom questionnaire (including hand diagrams) and physical examination (including Tinel's and Phalen's tests). Differences in SNC velocity between the little and index finger were compared according to the anatomical distribution of symptoms in the hand and findings on physical examination.

RESULTS

Analysis was based on 1806 hands in 908 patients (response rate 73%). In hands with numbness or tingling but negative on both Tinel's and Phalen's tests, the mean difference in SNC velocities was no higher than in hands with no numbness or tingling. The largest differences in SNC velocities occurred in hands with extensive numbness or tingling in the median nerve sensory distribution and both Tinel's and Phalen's tests positive (mean 13.8, 95% confidence interval (CI) 12.6-15.0 m/s). Hand pain and thumb weakness were unrelated to SNC velocity.

CONCLUSIONS

Our findings suggest that in the absence of other objective evidence of median nerve dysfunction, there is little value in referring patients of working age with suspected CTS for nerve conduction studies if they are negative on both Tinel's and Phalen's tests. Alternative case definitions for CTS in epidemiological research are proposed according to the extent of diagnostic information available and the relative importance of sensitivity and specificity.

Axonal degeneration of the ulnar nerve secondary to carpal tunnel syndrome: fact or fiction?

The distribution of sensory symptoms in carpal tunnel syndrome is strongly dependent on the degree of electrophysiological dysfunction of the median nerve. The association between carpal tunnel syndrome and ulnar nerve entrapment is still unclear. In this study, we measured ulnar nerve function in 82 patients with carpal tunnel syndrome. The patients were divided into group I with minimal carpal tunnel syndrome (n = 35) and group II with mild to moderate carpal tunnel syndrome (n = 47) according to electrophysiological data. Sixty-one age- and sex-matched subjects without carpal tunnel syndrome were used as a control group. There were no significant differences in ulnar sensory nerve peak latencies or conduction velocities from the 4^th and 5^th fingers between patients with carpal tunnel syndrome and the control group. The ulnar sensory nerve action potential amplitudes from the 4^th and 5^th fingers were lower in patients with carpal tunnel syndrome than in the control group. The ratios of the ulnar sensory nerve action potential amplitudes from the 4^th and 5^th fingers were almost the same in patients with carpal tunnel syndrome as in the control group. These findings indicate that in patients with minimal to moderate carpal tunnel syndrome, there is some electrophysiological evidence of traction on the adjacent ulnar nerve fibers. The findings do not indicate axonal degeneration of the ulnar nerve.

Median nerve small- and large-fiber damage in carpal tunnel syndrome: a quantitative sensory testing study

We explored the contribution of median nerve small (Aδ, C)-and large (Aβ)-fiber damage to the severity and topographic distribution of sensory symptoms in carpal tunnel syndrome (CTS) and the timing of fiber damage across CTS stages. We recruited 106 CTS patients. After selection, 49 patients were included. They underwent electrodiagnostic and quantitative sensory testing (QST) study and were asked on the severity of Boston Carpal Tunnel Questionnaire (BCTQ) Symptoms Severity Scale, daytime pain (DP), night pain and paresthesia, on the distribution of hand symptoms, and the presence of proximal symptoms. BCTQ Symptoms Severity Scale and DP severity was significantly correlated with Aδ-fiber damage. Small-fiber QST measures were impaired in electrodiagnostic-negative CTS patients and did not change across CTS neurographic stages. QST findings were not correlated to the topographical distribution of symptoms. Aδ-fiber damage contributes to CTS symptoms and in particular to DP. Night pain and paresthesia might be ascribed to ectopic fiber discharges secondary to median nerve enhanced mechanosensitivity. Small-fiber damage takes place earlier than large fiber. Median nerve fiber involvement does not directly contribute to extraterritorial symptoms spread. Our data may help understanding CTS pathophysiology and explain the well-known discrepancy between CTS symptoms and electrodiagnostic findings.

PERSPECTIVE

We explored the involvement of median nerve small and large fibers in carpal tunnel syndrome (CTS). We found a significant correlation between Aδ-fiber function and CTS symptoms. Small-fiber involvement took place in milder disease stages. These findings could help reconcile the discrepancy between CTS symptoms and electrodiagnostic data.

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.