Neurophysiologic recovery after carpal tunnel release in diabetic patients

ObjectiveTo compare nerve conduction study results, before and after surgical carpal tunnel release, in diabetic and non-diabetic patients.MethodsIn 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.ResultsDiabetic 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.ConclusionsMarked neurophysiologic impairment of the median nerve, or signs of peripheral neuropathy, does not preclude significant recovery after carpal tunnel release in diabetic patients.SignificanceDiabetic patients with CTS should be offered the same opportunities for surgical carpal tunnel release as non-diabetic patients.     

Median nerve ultrasound in diabetic peripheral neuropathy with and without carpal tunnel syndrome

Introduction: Median nerve ultrasound shows increased cross‐sectional area (CSA) in carpal tunnel syndrome (CTS) and diabetic peripheral neuropathy (PN). The role of ultrasound in diagnosing CTS superimposed on diabetic PN is unknown. The objective of this study is to evaluate ultrasound for diagnosis of CTS in diabetic PN. Methods: Prospective recruitment of diabetics with electrodiagnostically proven PN, subdivided into cases (with CTS) or controls (without CTS). The gold standard for CTS was clinical diagnosis. NCS were correlated with blinded median nerve CSA ultrasound measurements. Results: Eight cases (CTS) and eight controls (no CTS) were recruited. Nerve conduction studies (NCS): Median nerve distal latencies (antidromic sensory; palmar; lumbrical motor; and lumbrical motor to ulnar interosseous difference) were significantly prolonged in CTS cases. No ultrasound measurement (distal median CSA, wrist‐forearm ratio, wrist‐forearm difference) reached significance to detect CTS. Area under the curve was greatest for lumbrical distal latency by receiver operator characteristic analysis (0.85). Conclusions: In this pilot study, NCS may be superior to ultrasound for identification of superimposed CTS in diabetic PN patients, but larger numbers are needed for confirmation. Muscle Nerve 47: 437–439, 2013     

Management of extreme carpal tunnel syndrome: Evidence from a long‐term follow‐up study

Extreme carpal tunnel syndrome (CTS) is characterized by severe thenar atrophy, plegia of the abductor pollicis brevis (APB), fixed sensory deficit in the median nerve distribution, and absence of median motor and sensory responses on electrophysiological examination. In this study we report long‐term follow‐up of 37 patients with extreme CTS. Of the 24 patients with idiopathic extreme CTS, 9 were untreated, and 3 received conservative treatment. At follow‐up, none of these patients showed objective or electrophysiological improvement, and all but 1 still reported positive symptoms. Conversely, 12 patients (14 hands) who underwent carpal tunnel release showed: resolution of positive symptoms in all but 1 hand; reappearance of median compound muscle action potentials (4.2 ± 0.6 mV); reappearance of sensory nerve action potentials in all but 1 (7.9 ± 0.8 μV); improvement of APB strength to grade 4 or 5 on the Medical Research Council scale in 11 hands; and resolution of hypesthesia in 1 hand. Six of 13 patients with non‐idiopathic extreme CTS were operated. Of the 6, we found no or poor reinnervation in 3 patients, restoration of nerve responses and normal APB strength but no relief from pain and/or paresthesia in 2, and full recovery in 1. If untreated, extreme CTS is an irreversible condition. Although the outcome is considered to be disappointing in such cases, carpal tunnel release provides long‐term relief, significant sensorimotor reinnervation, and improvement of motor deficit in most patients. It should be considered to be the first‐choice treatment for idiopathic extreme CTS. Associated diseases do not necessarily imply a poor surgical outcome. Muscle Nerve, 2009     

Premotor potential study in carpal tunnel syndrome

Introduction: Premotor potentials (PMPs) precede compound muscle action potentials evoked from the second lumbrical muscle after median nerve stimulation. Although PMP has been identified as a median sensory nerve action potential, few reports have documented the significance of PMP parameters for diagnosing carpal tunnel syndrome (CTS). Methods: We investigated the relationships between PMP parameters and results of 6 standard median nerve conduction studies in 74 CTS hands. Results: Significant correlations were noted in all comparisons. PMP conduction velocity was strongly correlated with the sensory conduction velocity between wrist and digit 2 (r² = 0.91). Moreover, PMP parameters were significantly correlated with neurophysiological severity of CTS. Conclusion: Measuring PMP parameters with a second lumbrical–interosseous study may be useful for diagnosing CTS. Muscle Nerve, 2012     

Incidence of carpal tunnel syndrome in adult patients with mitochondrial disease

Symmetrical polyneuropathy is a common feature of mitochondrial disease. Both axonal and demyelinating types are described, with Schwann cell abnormalities demonstrated on nerve biopsy. Some authors have also suggested an increased incidence of entrapment neuropathy. We identified 738 adult patients with proven mitochondrial disease seen in our centre in the past 25 years. One‐hundred sixty seven of these patients had undergone nerve conduction studies as part of their routine clinical care, and the results of these studies were reviewed. We found an incidence rate of carpal tunnel syndrome (CTS) of 50.7 per 100,000 person‐years; 32.5 per 100,000 person‐years for men and 65.3 per 100,000 person‐years for women. One other patient had evidence of ulnar neuropathy at the elbow. The incidence of CTS in mitochondrial disease is similar to published rates for the UK general population. We found no evidence that mitochondrial disease per se increases the risk of entrapment neuropathy. We suggest that the pathophysiological mechanisms for the development of polyneuropathy in mitochondrial disease are quite distinct from the pathophysiology of CTS. Furthermore, it is essential that patients with mitochondrial disease who present with upper limb paraesthesia be referred for neurophysiological testing, so that treatable CTS is not missed.     

Neuromuscular ultrasound in common entrapment neuropathies

Neuromuscular ultrasound involves the use of high‐resolution ultrasound to image the peripheral nervous system of patients with suspected neuromuscular diseases. It complements electrodiagnostic studies well by providing anatomic information regarding nerves, muscles, vessels, tendons, ligaments, bones, and other structures that cannot be obtained with nerve conduction studies and electromyography. Neuromuscular ultrasound has been studied extensively over the past 10 years and has been used most often in the assessment of entrapment neuropathies. This review focuses on the use of neuromuscular ultrasound in 4 of the most common entrapment neuropathies: carpal tunnel syndrome, ulnar neuropathy at the elbow and wrist, and fibular neuropathy at the knee. Muscle Nerve 48:696–704, 2013     

Neuropathic pain in post-burn hypertrophic scars: a psychophysical and neurophysiological study

Introduction: Pain complicates hypertrophic post‐burn pathologic scars (PPS) Methods: To investigate the possible neuropathic origin of pain, 13 patients with painful PPS involving at least 1 hand underwent clinical examination, including the Douleur Neuropathique en 4 questions (DN4) questionnaire; median, ulnar, and radial nerve conduction studies (NCS); cold‐ (CDT) and heat‐induced pain threshold evaluation by quantitative sensory testing; and cutaneous silent period (CSP) testing of the abductor pollicis brevis. Controls included 9 patients with non‐painful PPS, 52 healthy subjects, and 28 patients with carpal tunnel syndrome (CTS). Results: All patients with painful PPS had possible neuropathic pain (DN4 score ≥4). NCS signs of CTS were similarly present in PPS subjects with or without pain. Hands with painful PPS had lower CDT and CSP duration, more frequent cold‐ and heat‐pain hypesthesia, and more thermal allodynia than controls. Conclusions: In PPS, possible neuropathic pain is associated with psychophysical and neurophysiological abnormalities suggestive of small‐fiber damage. Muscle Nerve 45: 883–890, 2012     

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.     

Natural history of median nerve sensory conduction in industry: Relationship to symptoms and carpal tunnel syndrome in 558 hands over 11 years

We evaluated the natural history of median nerve sensory conduction, hand/wrist symptoms, and carpal tunnel syndrome (CTS) in an 11-year longitudinal study of 289 workers from four industries. Twenty hands which had carpal tunnel release surgery were excluded, leaving 558 hands for the primary study group. Overall, the trend was for mean sensory latencies and prevalence of slowing to increase, the prevalence of symptoms to decrease, and the prevalence of CTS to remain unchanged. Among individual hands, nerve conduction abnormalities tended to persist (82% 11-year persistence), while symptoms fluctuated widely (13% 11-year persistence). There was a strong, direct linear correlation between initial severity of slowing and subsequent development of CTS; however, most workers who developed de novo slowing did not develop symptoms or CTS. We conclude that changes in conduction status of the median nerve occur naturally with increasing age and do not necessarily lead to symptoms and CTS. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:711–721, 1998.     

Characteristics of forearm mixed nerve conduction study in carpal tunnel syndrome: Comparison with ultrasound assessments

This study aimed to characterize forearm mixed nerve conduction study (NCS) findings in carpal tunnel syndrome (CTS). Eighty-two patients with CTS and 48 healthy controls were enrolled. We directly compared the forearm mixed NCS and ultrasonography results from CTS patients with those from the controls. Correlation analyses were performed to identify the relationship between forearm mixed NCS parameters and ultrasound measurements in CTS. We observed reduced forearm mixed nerve amplitude and increased cross-sectional area (CSA) of the median nerve at the proximal carpal tunnel (CT) inlet in CTS. The forearm mixed nerve amplitude negatively correlated with the CSA at the proximal CT inlet. We found a negative correlation between Bland's neurophysiological grade and the forearm mixed nerve amplitude as well as a positive correlation between the CSA of the median nerve at the proximal CT inlet and Bland's neurophysiological grade. We confirmed that the reduced median mixed nerve amplitude is the distinguishing feature of forearm mixed NCS in CTS. Our findings suggest that the forearm mixed NCS is potentially useful in evaluating its severity.     

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     

Prognostic factors in carpal tunnel syndrome treated with a corticosteroid injection

Introduction: Symptoms often return in patients with carpal tunnel syndrome (CTS) who are treated with a local corticosteroid injection. We aimed to determine prognostic factors for a successful long‐term outcome. Methods: We prospectively followed 113 patients who received an injection for CTS. Clinical, electrophysiological, and ultrasonographic tests were done at baseline, and clinical outcome was evaluated after 1, 3, 6, and 12 months. The primary outcome measure for success was no need for additional treatment (e.g., surgery) within 1 year. Results: After 1 month, most patients improved, but after 12 months 67.4% had surgery. Patients with a successful outcome had a lower median nerve ultrasonographic cross‐sectional area (CSA) at the pisiform bone, a lower swelling ratio, and a lower symptom severity score. Conclusions: Less pronounced median nerve swelling measured by ultrasonography may indicate a less severe stage of CTS, which is more likely to respond to treatment with a corticosteroid injection. Muscle Nerve, 2011     

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     

Sonographic median nerve change after steroid injection for carpal tunnel syndrome

Introduction: The sonographic changes of the median nerve after steroid injection for carpal tunnel syndrome (CTS) still require investigation. Methods: Sixty‐two patients with CTS were included. The Boston Carpal Tunnel Questionnaire was administered, and ultrasonographic examinations were performed before and at 2, 6, and 12 weeks after steroid injection. At 12 weeks, general improvement was scored on a 6‐point Likert scale. Results: After treatment, the cross‐sectional area (CSA) of the median nerve was significantly reduced at 2‐, 6‐, and 12‐week follow‐ups (for each, P < 0.001, analysis of variance). The “significant improvement” group (n = 39) had a significantly greater reduction in the CSA at the carpal tunnel inlet (P = 0.014) and CSA in the proximal carpal tunnel (P = 0.003) compared with the “little/no improvement” group (n = 23). Discussion: Sonographic measurement of CSA may be considered complementary to the standard clinical evaluation in monitoring of treatment response in patients with CTS. Muscle Nerve 58 : 402–406, 2018     

Median nerve changes following steroid injection for carpal tunnel syndrome

Introduction: Neuromuscular ultrasound is a painless, radiation‐free, high‐resolution imaging modality for assessment of the peripheral nervous system. The purpose of this study was to use neuromuscular ultrasound to assess the changes that occur in the median nerve after steroid injection for carpal tunnel syndrome (CTS). Methods: Ultrasound and nerve conduction studies were performed at baseline and 1 week, 1 month, and 6 months after steroid injection in 19 individuals (29 wrists) with CTS. Results: Significant changes were noted in median nerve cross‐sectional area (P < 0.001), mobility (P = 0.001), and vascularity (P = 0.042) at the distal wrist crease after steroid injection, and the nerve cross‐sectional area correlated with symptom score and electrodiagnostic parameters. Changes in the ultrasonographic parameters were seen within 1 week of injection. Conclusions: These findings suggest neuromuscular ultrasound is potentially helpful for the assessment of individuals undergoing treatment for CTS, as typical changes can be expected after successful treatment injection. Muscle Nerve 44: 25–29, 2011     

Nerve conduction in the hands of vibration exposed workers.

Symptoms of peripheral neuropathy in the hands are common among workers using vibrating tools. The mechanism for this and its relation to carpal tunnel syndrome (CTS) was studied in workers exposed to vibration at their workplace (17), along with a control group of healthy construction workers with heavy manual work but without vibration exposure (10). Patients with uni- or bilateral CTS (11) and a group of healthy volunteers without manual work (9) were included for comparison. Median nerve conduction velocities were measured both over the carpal tunnel and in a more distal segment. Vibration exposed workers had similar conduction velocities to unexposed construction workers. The subgroup of vibration exposed patients with symptoms from the hands had normal conduction in the ulnar nerve but demonstrated a decrease in median nerve conduction comparable (but less pronounced) with the CTS group. On a group basis these results indicated that the median nerve is most vulnerable for hand-arm vibrations. However, the conduction defects were not pronounced enough to diagnose CTS in most individual cases.     

Questionnaire tools for the diagnosis of carpal tunnel syndrome from the patient history

Introduction: There remains no “gold standard” for the diagnosis of carpal tunnel syndrome (CTS). Clinical diagnosis is often held to be paramount but depends on the skills of the individual practitioner. We describe two mathematical approaches to the analysis of a history obtained by questionnaire. Methods: We used two earlier instruments, a conventional logistic regression analysis, and an artificial neural network to analyze data from 5860 patients referred for diagnosis of hand symptoms. We evaluated their ability to predict whether nerve conduction studies would show evidence of CTS using receiver operating characteristic curves. Results: Both new instruments outperformed the existing tools, achieving sensitivity of 88% and specificity of 50% in predicting abnormal median nerve conduction. When combined, 96% sensitivity and 50% specificity were achieved. Conclusion: The combined instrument can be used as a preliminary screening tool for CTS, for self‐diagnosis, and as a supplement to diagnosis in primary care. Muscle Nerve, 2011     

Corticosteroid iontophoresis to treat carpal tunnel syndrome: A double‐blind randomized controlled trial

Even though injection of corticosteroids into the carpal tunnel alleviates the symptoms of mild to moderately severe carpal tunnel syndrome (CTS), it has not gained universal popularity due to its invasiveness. This study was designed to investigate the effectiveness of dexamethasone iontophoresis as a noninvasive method of treating CTS. We carried out a double‐blind randomized controlled trial comparing six sessions of iontophoresis with 0.4% dexamethasone sodium phosphate with distilled water in 17 patients. Outcome measures including nerve conduction studies, the Levine Self‐Assessment Questionnaire, and the Semmes–Weinstein Monofilaments were done monthly for 6 months after intervention. Most of the outcome measures did not show any significant change following treatment. Although there was subjective improvement of symptom severity scores in the treatment group as quantified by the Levine Self‐Assessment Questionnaire, similar improvement was also observed in the control group (P < 0.05). Although corticosteroid iontophoresis is feasible in clinical settings and is well‐tolerated by patients, iontophoresis of 0.4% dexamethasone was not effective in the treatment of mild to moderate CTS. Muscle Nerve 39: 627–633, 2009     

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     

Bifid median nerve in carpal tunnel syndrome: Do we need to know?

Introduction: We tested the hypothesis that a bifid median nerve predisposes to development of carpal tunnel syndrome (CTS) and investigated differences in electrophysiological findings and outcome. Methods: A total of 259 consecutive patients with clinically defined CTS were included and investigated clinically, electrophysiologically, and ultrasonographically. Fifty‐four healthy asymptomatic volunteers were investigated ultrasonographically. Results: The prevalence of bifid median nerves is equal in patients with CTS and controls. Electrophysiological and ultrasonographic abnormalities are more pronounced in patients with non‐bifid median nerves. Some outcome data are better in patients with non‐bifid median nerves, but others do not show significant differences. Conclusions: A bifid median nerve is not an independent risk factor for development of CTS. Some of our data suggest outcome after surgical decompression to be different, but others do not. The surgical technique in these patients may therefore have to be reevaluated. Muscle Nerve 50 : 835–843, 2014