AAEM case report #2: The carpal tunnel syndrome

The symptoms and sings which constitute the carpal tunnel syndrome (CTS) result from entrapment or compression of the median nerve within the carpal tunnel. Electrodiagnostic studies may objectively document the presence of median neuropathy within the carpal tunnel and help distinguish CTS from other disorders such as cervical radiculopathy, neurogenic thoracic outlet syndrome, proximal median nerve compression syndromes, and polyneuropathy which may either mimic or occasionally coexist with CTS. Recording median nerve responses with wrist and palm stimulation allows determination of the wrist segment conduction velocity which is a more sensitive nerve conduction parameter than wrist latency measurements. Electrodiagnostic testing permits estimation of severity and relative contribution of axonal versus demyelinative nerve injury. This information can provide prognostic information and help guide therapeutic decisions. © 1995 Mark A. Ross, MD and Jun Kimura, MD. Published John Wiley & Sons, Inc.     

Serial studies of carpal tunnel syndrome during and after pregnancy

Carpal tunnel syndrome (CTS) is a frequent and underdiagnosed complication of pregnancy. Conservative therapies are common initial measures, but data on the course of improvement are limited. We report a case of pregnancy-associated CTS with unusually detailed serial electrophysiologic studies before and after wrist splinting. Physiologic measures reached a nadir and then rapidly improved following conservative therapy, paralleling clinical improvement. Responses took between 6 and 20 months postpartum to approach baseline values.     

Intracarpal steroid injection is safe and effective for short-term management of carpal tunnel syndrome

A double-blinded placebo-controlled trial was performed to evaluate the use of steroid injections beneath the transverse carpal ligament in the treatment of carpal tunnel syndrome (CTS) refractory to nonsurgical therapy. Forty-three patients received 6 mg betamethasone and lidocaine and 38 patients received 1 ml saline placebo and lidocaine. The primary outcome measure was satisfaction with symptom relief. Thirty patients (70%) in the steroid-treated group were satisfied or highly satisfied compared with 13 (34%) of placebo-treated patients (P < 0.001). Patients receiving steroids also showed significant improvement in median nerve conduction parameters and scores on validated symptom/function questionnaires. Forty-six patients were treated with serial injections for recurrent CTS symptoms. After 18 months, 17 patients reported adequate symptom relief with steroid injection, and 18 patients with unsatisfactory symptom relief were referred for carpal tunnel release surgery. We conclude that although steroid injections are safe and effective for temporary relief of CTS, most patients will eventually require surgery for long-term control of their symptoms.     

Antibodies to Borrelia burgdorferi in patients with carpal tunnel syndrome

In a study of 94 consecutive patients with neurophysiologically verified carpal tunnel syndrome (CTS) 7/94 had IgG and 0/94 IgM serum titers to Borrelia burgdorferi above the 98th percentile value of age and sex matched controls (n = 127). The difference in prevalence of positive IgG serum titers in patients, compared to controls, was not statistically significant. Even in patients, living in an area, highly endemic for Lyme borreliosis, routine serological screening for borrelia infection does not seem indicated in the investigation of CTS.     

Grading severity of carpal tunnel syndrome in electrodiagnostic reports: Why grading is recommended

Carpal tunnel syndrome (CTS) is not difficult to confirm by electrodiagnosis (EDx), but the challenge lies in whether to grade the severity and the method for doing so. The arguments about grading are discussed, with an emphasis in favor, using a method that relies on the EDx data, but qualifies that it is the median neuropathy being graded and not the syndrome of CTS. Although use of latencies can be arbitrary and misleading, it is possible to apply other criteria, such as low amplitudes or conduction block and denervation, to develop a grading scale that could be applied widely. Several previously published grading schemes are reviewed, and a new method is described that combines the prior ranking criteria into 3 basic categories. Application of a grading system identifies the degree of nerve injury and thus allows the referring physician to utilize optimally the EDx report to manage the patient. Muscle Nerve 48 : 331–333, 2013     

Ultrasound findings of carpal tunnel syndrome in a hunter syndrome patient

Introduction: Hunter syndrome (mucopolysaccharidosis II) is a rare genetic disorder. Carpal tunnel syndrome (CTS) is a common finding in these patients. Methods: We report the ultrasound findings in a 40‐year‐old Hunter syndrome patient with severe CTS. Results: Marked abnormalities of the median nerve were present proximal to the carpal tunnel with an unusual area of increased echogenicity between enlarged fascicles separating the area of maximal enlargement and the normal median nerve proximally. Conclusions: This case demonstrated unique ultrasound findings in a Hunter syndrome with CTS. Ultrasound also localized the median nerve lesion in the setting of end‐stage median neuropathy and nonlocalizing electrophysiology. Muscle Nerve 53 : 147–150, 2016     

Electrodiagnostic evaluation of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common nerve entrapment. Electrodiagnostic (EDX) studies are a valid and reliable means of confirming the diagnosis. This monograph addresses the various EDX techniques used to evaluate the median nerve at the wrist. It also demonstrates the limitations of EDX studies with a focus on the sensitivity and specificity of EDX testing for CTS. The need to use reference values for populations such as diabetics and active workers, where normative values differ from conventional cutoffs used to confirm suspected CTS, is presented. The value of needle electromyography (EMG) is examined.     

Limited longitudinal sliding of the median nerve in patients with carpal tunnel syndrome

During normal movements or changes in position of the limbs, nerve structures must accommodate the resulting changes in length of the nerve path. In patients with carpal tunnel syndrome, we monitored electrophysiologically the longitudinal adjustment of the median nerve to positions of extreme flexion and extreme extension of the wrist and elbow, by measuring the differences induced in the latency of the sensory nerve action potential (SNAP) recorded in the forearm and upper arm. In patients, the latency difference was significantly shorter than in normal subjects (0.196 ± 0.084 ms vs. 0.088 ± 0.059 ms in the forearm, and 0.485 ± 0.122 ms vs. 0.129 ± 0.086 ms in the upper arm). These results indicate that the displacement of the source of the median nerve SNAP with movements of flexion and extension is limited in patients with carpal tunnel syndrome. Such an abnormality may partly underlie the pathophysiology of entrapment syndromes. © 1995 John Wiley & Sons, Inc.     

Familial carpal tunnel syndrome: a report of a Finnish family

The existence of familial carpal tunnel syndrome (FCTS) as a separate autonomic entity has been discussed during the last few years. In order to contribute with more data to the literature, we report here the results of clinical. electrophysiological, pathological and radiological studies performed in 5 patients belonging to the same Finnish pedigree. The disease appeared usually before the second decade with numbness and pain on the I--III digits. In most patients symptoms were unilateral but within 2 years they became bilateral. In all patients typical electrophysiological features of median nerve entrapment have been recorded. X-rays of the wrist showed narrow carpal tunnel in all patients. In all patients the possibility of having HNPP as well as familial amyloidosis has been excluded by molecular genetic and pathological studies. All patients underwent surgery and at postoperative stage symptoms were relieved or completely disappeared. Our study supports the theory that FCTS exists as a separate autonomic entity, therefore it is important in front of a sporadic case to investigate the family occurrence of CTS.     

Seasonal variation in prevalence of carpal tunnel syndrome

Introduction: The influence of cold temperatures on neuropathies has been reported previously, but its impact on carpal tunnel syndrome (CTS) is not well analyzed. Methods: We analyzed the frequency of CTS among neurophysiological evaluations according to seasonal variation in 9574 consecutive patients (4260 with CTS). Results: A higher frequency of CTS was found in the winter (50.8%), and the lowest number for CTS diagnosis was found in the summer (38.9%). In both autumn and spring the prevalence remained stable at an intermediate level between summer and winter at 42.8% and 43.5%, respectively. Conclusion: CTS frequency was much higher in winter in this center. Muscle Nerve 47: 925–927, 2013     

Ulnar nerve conduction abnormalities in carpal tunnel syndrome

Introduction: The aim of this study was to verify the involvement of ulnar nerve fibers in cases of carpal tunnel syndrome (CTS) and investigate the correlation between ulnar nerve conduction parameters and extra‐median spread of symptoms. Methods: Electrophysiological studies were conducted in 93 CTS and 76 control hands. Patients were analyzed with regard to symptoms in the fifth finger. Results: In the CTS cases, ulnar distal motor latency (DML) and distal sensory latency (DSL) were significantly longer, and amplitudes were lower than in controls. Increased median nerve DML correlated with increased ulnar nerve DSL and decreased sensory amplitudes and conduction velocities (SCVs). In cases with symptoms in the fifth finger, ulnar nerve SCVs and amplitudes were lower than in patients without symptoms. Conclusions: Pathological processes leading to median neuropathy in CTS may affect ulnar nerve motor and sensory fibers in the Guyon canal. This may explain the extra‐median spread of sensory symptoms in CTS patients. Muscle Nerve 44: 352–357, 2011     

Injection with methylprednisolone in patients with the carpal tunnel syndrome

Objective To determine the efficacy of 20, 40 and 60mg methylprednisolone injections in patients with the carpal tunnel syndrome. Methods Included were patients with signs and symptoms of carpal tunnel syndrome of more than 3 months duration confirmed by electrophysiological tests. Patients were in a double blind trial randomised to treatment consisting of injections proximal to the carpal tunnel with 20, 40 or 60mg methylprednisolone. Primary outcome was improvement of symptoms requiring no further treatment. These patients were followed for one year. Results There were no significant differences in the treatment response between the three randomised groups at one–year follow–up (log rank analysis 1.51, 2df, 0.4711). In the 20, 40 and 60mg treatment groups, 56%, 53% and 73% of the patients respectively were free of important symptoms at six months follow–up. Of the patients treated with one or two injections 22% were finally referred to surgery within one year of the first treatment. No side effects were recorded. Conclusion A single local injection of methylprednisolone 20, 40 or 60 mg results in long lasting improvement in approximately half of the patients. There is a trend in favour of the highest dose. A second injection may further reduce the number of patients requiring surgery.     

Improved inching method for the diagnosis and prognosis of carpal tunnel syndrome.

A modified sensory "inching" method for the electrodiagnosis of carpal tunnel syndrome (CTS) is described. The median nerve as stimulated at the cubital portion, with 8 channel recording electrodes placed along the nerve across the carpal tunnel. In most of the CTS cases, there was a conductive abnormality from 3 to 4.5 cm distal to the proximal ending of the flexor retinaculum. Subjects' values, obtained by subtracting the theoretical latency from the measured latency, which were more than 0.6 ms, could not be improved by conservative therapy. As we could determine from subtle change at the short span of nerve conduction, below the electrodes from the proximal to the affected site of the carpal tunnel, this method provides high sensitivity and specificity for the diagnosis of CTS.     

The dilemma of ulnar nerve entrapment at wrist in carpal tunnel syndrome

Objective

The commonest compression neuropathy in human being is carpal tunnel syndrome (CTS). The association between CTS and ulnar nerve entrapment is debatable. The objective of this study is to determine the presence of any association between CTS and ulnar entrapment neuropathy at the wrist.

Patients and methods

To test the hypothesis we conducted a case-control study. Ninety-nine healthy volunteers and 181 patients with established diagnosis of CTS enrolled to the study. Distal latencies, peak latencies and action potentials for sensory branches and distal latencies and action potentials for motor branches of both median and ulnar nerves were measured in totally 378 hands. We conducted independent t-test comparing age and sex between control and patient groups and analysis of variance to compare dichotomous and continuous variables between control group and patient subgroups.

Results

Based on our cutoffs, we found that 7.5% of CTS patients had distal latency ≥2.8 ms for ulnar sensory branches, 4.6% had distal latency ≥3.4 ms for ulnar nerve motor branches and 15% had peak latency ≥3.3 ms for ulnar sensory branches. There was not any statistically significant correlation between subgroups of CTS patients and control group.

Conclusion

The authors suggest that there may not be any association between CTS and ulnar nerve compression at the wrist. We suggest that different racial groups and multiple techniques in performing nerve conduction studies and dissimilar cutoff values for the diagnosis of entrapment neuropathies are the major causes of ambiguity in the literature. More relevant studies will have crucial importance for detecting ulnar nerve entrapment at the wrist in CTS patients.     

The refractory period of transmission in patients with carpal tunnel syndrome

In patients with the carpal tunnel syndrome (CTS) and in control subjects, pairs of shocks at intervals of 0.8 msec and 1.0 msec were used to stimulate the median nerve just above the wrist. Nerve action potentials were recorded at the elbow and from the index or middle finger. In patients but not in controls, recordings from the finger frequently showed loss of the second action potential of the pair, although a second action potential was present at the elbow. In these cases it seemed likely that impulse transmission through the carpal tunnel had failed because the damaged nerve at the level of the lesion had an increased refractory period of transmission (RPT) compared with its refractory period under the stimulating cathode. The possible diagnostic use of RPT measurement in CTS patients is discussed.     

Evaluation of carpal tunnel syndrome in patients with polyneuropathy

The difference between the median nerve latency to the second lumbrical muscle and the ulnar nerve latency to the second interosseous muscle (L-I DIFF) was tested in a prospective study to discriminate whether prolonged distal motor latency of the median nerve in patients with polyneuropathy (PNP) reflects an additional carpal tunnel syndrome (CTS). We investigated 92 patients (107 hands) with CTS, 30 patients (34 hands) with PNP, 22 patients (27 hands) with CTS and coexisting PNP (PNP+CTS), and 77 controls (87 hands). L-I DIFF was significantly prolonged in both the CTS and PNP+CTS patients as compared to PNP patients and controls. It proved to be the most specific test to differentiate between diffuse (PNP) and focal (entrapment) nerve disorder. © 1997 John Wiley & Sons, Inc. Muscle Nerve, 20, 153–157, 1997.     

Perineurial cell hypertrophic mononeuropathy manifesting as carpal tunnel syndrome.

A 42-year-old man showed signs and symptoms suggestive of carpal-tunnel syndrome, but EMG showed an isolated motor axon-loss lesion affecting the right median nerve distally. After the MRI revealed a mass in the median nerve, surgical exploration showed a diffusely swollen median motor branch. Biopsy showed a lesion with marked onion-bulb formation composed of perineurial cells as identified by immunohistochemical analyses and electron microscopic examination. Although we previously coined the term "perineurioma" for this condition, re-reviews of our cases do not support the idea that the onion-bulb lesion is a benign tumor; instead, it appears to be reactive hyperplasia. Although rare, electromyographers and neurologists need to be aware of this problem because it is self-limited and does not require surgical resection.     

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.     

Temperature effects on nerve conduction studies in patients with carpal tunnel syndrome

This study was done to evaluate the effect of rising temperature on nerve conduction parameters in 22 patients with carpal tunnel syndrome (CTS). We wanted to find out whether diseased nerves responded to temperature rise in a different manner from normal controls. For this purpose a group of 20 healthy individuals were also tested. With rising temperature motor nerve conduction velocities increased, whereas latencies, amplitudes and duration of the compound muscle action potential decreased in both groups. These changes were not statistically significant between the two groups. Sensory nerve conduction parameters yielded basically similar findings except for a significantly smaller reduction in amplitude of the compound nerve action potential (CNAP) in the CTS group (p <0.005). We conclude that there is a different response in the sensory CNAP amplitude between normal and CTS groups, but the same nerve conduction correction formulae for temperature can be used in CTS patients as in normal individuals in the event of low skin temperature.