Normal Sonographic Anatomy of the Wrist With Emphasis on Assessment of Tendons, Nerves, and Ligaments

Sonography allows for rapid, cost-effective, noninvasive, and dynamic evaluation of soft tissue structures, thus representing a valuable tool for ruling out musculoskeletal disorders of the wrist. Because of the complexity of the wrist joint, sonographic training and familiarity with normal and variant anatomy are needed to avoid misdiagnosis and improper treatment. The aim of this article is to enlighten readers about the structures representing normal findings or common variants during sonographic evaluations of the wrist. The main text reviews the pertinent gross anatomy and procedures that are recommended to assess the soft tissue structures of the wrist, with particular emphasis given to tendons, nerves, and ligaments. Detailed explanations of the scanning techniques and sonographic appearance of the wrist structures are provided in the figure legends.

Nerve Transfers for the Restoration of Wrist, Finger, and Thumb Extension After High Radial Nerve Injury

High radial nerve injury is a common pattern of peripheral nerve injury most often associated with orthopedic trauma. Nerve transfers to the wrist and finger extensors, often from the median nerve, offer several advantages when compared to nerve repair or grafting and tendon transfer. In this article, we discuss the forearm anatomy pertinent to performing these nerve transfers and review the literature surrounding nerve transfers for wrist, finger, and thumb extension. A suggested algorithm for management of acute traumatic high radial nerve palsy is offered, and our preferred surgical technique for treatment of high radial nerve palsy is provided.

Median nerve conduction studies and wrist magnetic resonance imaging in acromegalic patients with carpal tunnel syndrome

PURPOSE

Carpal tunnel syndrome (CTS) often occurs with acromegaly; however, the pathophysiology of CTS in acromegalic patients remains unclear. This study evaluated the median nerve in acromegalic patients with and without CTS.

METHODS

We examined the median nerves of 21 acromegalic patients (eight patients with CTS and 13 patients without CTS) using electrophysiological nerve conduction studies and wrist magnetic resonance images. They underwent transsphenoidal surgery to resect their growth hormone-secreting pituitary adenomas. The median nerves of the patients with CTS were reassessed by the same studies.

RESULTS

The sensory conduction velocity was significantly later in the median nerves of patients with CTS than in patients without CTS (34.9 vs. 45.8 m/s, respectively; P = 0.006). In the wrist magnetic resonance images, the cross-sectional area of the median nerve in CTS patients and non-CTS patients was 18.7 and 10.5 mm(2), respectively. The median nerve was significantly larger in patients with CTS than in patients without CTS (P < 0.003). The flattering ratio of the median nerve and palmar deviation of the flexor retinaculum were not significantly different between the two patient groups. After tumor resection, the nerve conduction velocities improved in patients with CTS, but the nerve remained enlarged. The CTS symptoms disappeared in all patients, except one.

CONCLUSIONS

The median nerves of acromegalic patients with CTS were enlarged and had impaired nerve conduction. This finding represents a predominant intrinsic feature in the pathophysiology of the disease rather than an extrinsic feature such as a thickened transverse carpal ligament.

The effect of force feedback delay on stiffness perception and grip force modulation during tool-mediated interaction with elastic force fields

During interaction with objects, we form an internal representation of their mechanical properties. This representation is used for perception and for guiding actions, such as in precision grip, where grip force is modulated with the predicted load forces. In this study, we explored the relationship between grip force adjustment and perception of stiffness during interaction with linear elastic force fields. In a forced-choice paradigm, participants probed pairs of virtual force fields while grasping a force sensor that was attached to a haptic device. For each pair, they were asked which field had higher level of stiffness. In half of the pairs, the force feedback of one of the fields was delayed. Participants underestimated the stiffness of the delayed field relatively to the nondelayed, but their grip force characteristics were similar in both conditions. We analyzed the magnitude of the grip force and the lag between the grip force and the load force in the exploratory probing movements within each trial. Right before answering which force field had higher level of stiffness, both magnitude and lag were similar between delayed and nondelayed force fields. These results suggest that an accurate internal representation of environment stiffness and time delay was used for adjusting the grip force. However, this representation did not help in eliminating the bias in stiffness perception. We argue that during performance of a perceptual task that is based on proprioceptive feedback, separate neural mechanisms are responsible for perception and action-related computations in the brain.

Ultrasound elastographic evaluation of the median nerve in pregnant women with carpal tunnel syndrome

OBJECTIVE

To evaluate the median nerve (MN) in pregnant women with carpal tunnel syndrome (CTS) by using ultrasound elastography.

PATIENTS AND METHODS

30 wrists of 20 pregnant women with CTS and 25 wrists of 14 healthy control pregnant women were evaluated by ultrasound and ultrasound elastography (UE). The MN in the patients' wrist was imaged to measure the cross-sectional area and longitudinally to calculate the elasticity value (EV) at four different locations (proximal carpal tunnel (CT) at the level of the pisiform, distal CT at the level of the hamate, middle of the CT and forearm at one centimeter above the CT). Clinical classification was performed according to a historic and objective scale of CTS. In the healthy pregnant women and pregnant women with CTS, MN area and EV were analyzed statistically by comparing with parity and clinical grade.

RESULTS

There was a statistically significant difference for MN area between the patient and control groups (p = 0.001). A positive relationship was found between parity in pregnancy and clinical grade of the CTS (p = 0.035, Pearson's correlation coefficient = 0.386). Although MN elasticity for both groups was nearly the same in the proximal region of the CT, these values were decreased in the middle of the CT. MN elasticity values were smaller in the distal region of CT, and it was statistically significant in pregnant women with CTS (p = 0.02).

CONCLUSIONS

Ultrasound elastography, which is a non-invasive, inexpensive and a favorable diagnosis technique, may be useful in the diagnosis of CTS, especially in conditions in which an invasive procedure would be problem, as in pregnancy.

Syndrome of canal of Guyon - definition, diagnosis, treatment and complication

Syndrome of canal of Guyon is the second after carpal tunnel syndrome, compression syndrome in the wrist. Opposite to median nerve compression, ulnar nerve compression is not very popular. However it impairs functioning of the hand even more than median nerve lesion. Authors deal with definition, possible diagnostic methods, treatment and most frequent complication.

Spatiotemporal dynamics of online motor correction processing revealed by high-density electroencephalography

The ability to control online motor corrections is key to dealing with unexpected changes arising in the environment with which we interact. How the CNS controls online motor corrections is poorly understood, but evidence has accumulated in favor of a submovement-based model in which apparently continuous movement is segmented into distinct submovements. Although most studies have focused on submovements' kinematic features, direct links with the underlying neural dynamics have not been extensively explored. This study sought to identify an electroencephalographic signature of submovements. We elicited kinematic submovements using a double-step displacement paradigm. Participants moved their wrist toward a target whose direction could shift mid-movement with a 50% probability. Movement kinematics and cortical activity were concurrently recorded with a low-friction robotic device and high-density electroencephalography. Analysis of spatiotemporal dynamics of brain activation and its correlation with movement kinematics showed that the production of each kinematic submovement was accompanied by (1) stereotyped topographic scalp maps and (2) frontoparietal ERPs time-locked to submovements. Positive ERP peaks from frontocentral areas contralateral to the moving wrist preceded kinematic submovement peaks by 220-250 msec and were followed by positive ERP peaks from contralateral parietal areas (140-250 msec latency, 0-80 msec before submovement peaks). Moreover, individual subject variability in the latency of frontoparietal ERP components following the target shift significantly predicted variability in the latency of the corrective submovement. Our results are in concordance with evidence for the intermittent nature of continuous movement and elucidate the timing and role of frontoparietal activations in the generation and control of corrective submovements.

An ergonomics study on the evaluation of carpal tunnel syndrome among Chikan embroidery workers of West Bengal, India

BACKGROUND

Chikan embroidery is a popular handicraft in India that involves hand-intensive stitching while seated in a static posture with the upper back curved and the head bent over the fabric. Women perform most Chikan embroidery.

OBJECTIVES

The aim of this study was to analyze the repetitive nature of this work among female Chikan embroiderers by measuring the prevalence of upper extremity discomfort and carpal tunnel syndrome (CTS).

METHODS

The Nordic musculoskeletal questionnaire was used to analyze the extent of upper extremity pain symptomology. The repetitive nature of Chikan embroidery work was evaluated using the Assessment of Repetitive Tasks of the upper limbs tool (ART). Motor nerve conduction studies of median and ulnar nerves were performed with embroidery workers and a control group to determine the risk of CTS.

RESULTS

Among embroidery workers, the prevalence of wrist pain was 68% and forearm pain was 60%. The embroiderers also commonly reported Tingling and numbness in the hands and fingertips. The ART analysis found that Chikan embroidery is a highly repetitive task and nerve conduction studies showed that the embroidery workers were more likely to experience CTS than women in the control group.

CONCLUSIONS

Chikan embroidery is a hand-intensive occupation involving repetitive use of hands and wrists and this study population is at risk of experiencing CTS. Future research should explore the potential benefits of ergonomics measures including incorporating breaks, stretching exercises, and the use of wrist splints to reduce repetitive strain and the probability of developing CTS.

Temporal trend of carpal tunnel release surgery: a population-based time series analysis

BACKGROUND

Carpal tunnel release (CTR) is among the most common hand surgeries, although little is known about its pattern. In this study, we aimed to investigate temporal trends, age and gender variation and current practice patterns in CTR surgeries.

METHODS

We conducted a population-based time series analysis among over 13 million residents of Ontario, who underwent operative management for carpal tunnel syndrome (CTS) from April 1, 1992 to March 31, 2010 using administrative claims data.

RESULTS

The primary analysis revealed a fairly stable procedure rate of approximately 10 patients per 10,000 population per year receiving CTRs without any significant, consistent temporal trend (p = 0.94). Secondary analyses revealed different trends in procedure rates according to age. The annual procedure rate among those age >75 years increased from 22 per 10,000 population at the beginning of the study period to over 26 patients per 10,000 population (p<0.01) by the end of the study period. CTR surgical procedures were approximately two-fold more common among females relative to males (64.9% vs. 35.1 respectively; p<0.01). Lastly, CTR procedures are increasingly being conducted in the outpatient setting while procedures in the inpatient setting have been declining steadily - the proportion of procedures performed in the outpatient setting increased from 13% to over 30% by 2010 (p<0.01).

CONCLUSION

Overall, CTR surgical-procedures are conducted at a rate of approximately 10 patients per 10,000 population annually with significant variation with respect to age and gender. CTR surgical procedures in ambulatory-care facilities may soon outpace procedure rates in the in-hospital setting.

Reliability of peripheral intraneural microhemodynamics evaluation by using contrast-enhanced ultrasonography

PURPOSE

The purpose of the study was to validate the reliability of quantitative intraneural enhancement patterns by using contrast-enhanced ultrasonography (CEUS).

METHODS

Nine asymptomatic wrists underwent a total of three CEUS examinations each conducted at 1-month intervals. The CEUS enhancement pattern of median nerves was quantitatively evaluated. The area under the time-intensity curve was calculated by placing the regions of interest at the proximal, center, and distal regions of the median nerve. An intra-class correlation coefficient for intra-observer, inter-observer, and inter-examination reproducibility was calculated.

RESULTS

The intra- and inter-observer reproducibility was almost perfect. Inter-examination reproducibility of the proximal, center, and distal regions was 0.891, 0.614, and 0.535, respectively. In this study, we found that the reproducibility of the distal and center regions of the median nerve in the carpal tunnel was lower than that of the proximal region.

CONCLUSION

High intra-observer, inter-observer, and inter-examination reproducibility of CEUS was obtained in the evaluation of the intraneural enhancement pattern when the region of interest was placed in the proximal region of the median nerve.

Guyon's tunnel syndrome during pregnancy with concomitant anomalous arch of the ulnar nerve: a case report

Numerous causes are reported for ulnar nerve compression at the wrist, known as Guyon's tunnel syndrome. In the present article, a patient with Guyon's tunnel syndrome during pregnancy concomitant with an anomaly of ulnar nerve is described. A 29-year-old Iranian woman presented with clinical features of Guyon's tunnel syndrome (pain and paresthesia in the fifth finger of the left hand and atrophy of the first dorsal interosseus muscle). Symptoms of the patient appeared during the third trimester of pregnancy. Electro diagnostic studies confirmed Guyon's tunnel syndrome. Surgical exploration revealed an anomalous arch of the ulnar nerve passing through the flexor carpi ulnaris (FCU) tendon. The anomalous arch of the ulnar nerve was released by resection of the segment of FCU tendon passing through the ulnar nerve arch. Therefore, in patients with Guyon's tunnel syndrome, the ulnar nerve anomaly should be kept in mind as a cause. Moreover, pregnancy may have a provocative effect on Guyon's tunnel syndrome similar to carpal tunnel syndrome (CTS).

Finger position alters the median nerve properties within the carpal tunnel: a pre-post MRI comparison study

Purpose

The purpose of this study was to compare the properties of the median nerve and the flexor retinaculum within the carpal tunnel with Magnetic Resonance Imaging (MRI) under two conditions: (a) fingers extended, and (b) fingers in an isometric squeeze grip.

Methods

Thirty-Four volunteers participated in this experimental study. The flexor retinaculum and median nerve characteristics were measured during both conditions using MRI.

Results

The isometric squeeze grip condition resulted in significant palmar bowing of the flexor retinaculum (t = 7.67, p<.001), a significant flattening-ratio of the median nerve (t = 4.308, p<.001), and no significant decrease in the cross-sectional area of the median nerve (t = 2.508, p = 0.017).

Conclusion

The isometric squeeze grip condition resulted in anatomical deformations within the carpal tunnel, possibly explained by the lumbrical muscles incursion into the carpal tunnel during finger flexion.

Feasibility of 3D ultrasound to evaluate upper extremity nerves

PURPOSE

This study investigates the performance of a 3 D Ultrasound (US) system in imaging elbow and wrist nerves.

MATERIALS AND METHODS

Twenty healthy volunteers with asymptomatic median, ulnar and radial nerves were prospectively investigated. Bilateral 3DUS scans of the elbows and wrists were acquired by using a commercially available US scanner (18 MHz, AplioXG, Toshiba) and stored as a 3 D volume by a dedicated software (CURE, Robarts Research Institute). Retrospectively, qualitative (image quality, atypical nerve location, findings potentially associated with compression neuropathy) and quantitative (cross-sectional area measurements) evaluations were performed.

RESULTS

In all 200 nerves 3DUS was feasible (100%). Image quality was insufficient in 13.5% (25 ulnar nerve elbow, 2 radial nerve) and sonomorphology was not assessable in those nerves. Measurement of cross sectional areas was feasible in all nerves (100%). Median cross-sectional area (range) were: median nerve elbow 7 mm2 (6-9), radial nerve 3 mm2 (1-4), ulnar nerve elbow 8 mm2 (5-11), median nerve wrist 8 mm2 (5-10), and ulnar nerve wrist 4 mm2 (2-6). No significant changes in nerve cross-sectional area along each nerve was found. Ulnar nerve subluxation was found in 2 nerves (6.7%). No anconeus epitrochlearis muscle or osteophytes were found.

CONCLUSION

3DUS is a feasible method for assessing nerves of the upper extremity and has been shown to provide a good overview of the median, ulnar and radial nerve at the elbow and wrist, but is limited for evaluation of the ulnar nerve in the cubital tunnel. This technique enables reliable measurements at different locations along the nerve.

[Anatomy study on micro transverse flap pedicled with superfical palmar branch of radial artery from palmar wrist]

OBJECTIVE

To study the anatomical basis of micro transverse flap pedicled with the superfical palmar branch of radial artery from the palmar wrist for using this free flap to repair soft tissue defect of the finger.

METHODS

Thirty-eight fresh upper limb specimens (22 males and 16 females; aged 26-72 years with an average of 36 years; at left and right sides in 19 limbs respectively) were dissected and observed under operating microscope. Two specimens were made into casting mould of artery with bones, and 2 specimens were injected with red emulsion in radial artery. Thirty-four specimens were injected with 1% gentian violet solution in the superfical palmar branch of the radial artery. A transverse oval flap in the palmar wrist was designed, the axis of the flap was the distal palmar crease. The origin, distribution, and anastomosis of the superfical palmar branch of the radial artery were observed.

RESULTS

The superficial palmar branch of the radial artery was constantly existed, it usually arises from the main trunk of the radial artery, 1.09-3.60 cm to proximal styloid process of radius. There were about 2-5 branches between the origin and the tubercle of scaphoid bone. The origin diameter was 1.00-3.00 mm, and the distal diameter at the styloid process of radius was 1.00-2.90 mm. The venous return of flap passed through 2 routes, and the innervations of the flap mainly from the palmar cutaneous branch of the median nerve. The area of the flap was 4 cm x 2 cm-6 cm x 2 cm.

CONCLUSION

The origin and courses of the superficial palmar branch of the radial artery is constant, and its diameter is similar to that of the digital artery. A transverse oval flap pedicled with the superfical palmar branch of radial artery in the palmar wrist can be designed to repair defects of the finger.

Correlation between subclinical median neuropathy and the cross-sectional area of the median nerve at the wrist

Although subclinical median neuropathy is not uncommon, its correlation with sonographic changes to the median nerve at the wrist has not been studied. We included 62 subjects (with 107 wrists) who reported experiencing no hand numbness. All subjects underwent nerve conduction studies (NCS) and sonography for median nerve at the pisiform level. The cross-sectional area (CSA), perimeter, long axis and short axis of median nerve were obtained off-line by manual tracing with a mouse and computed by one algorithm written in MatLab. Eighteen wrists met the inclusion criteria of subclinical median neuropathy. The CSA, perimeter and long axis of the median nerve were significantly different between normal and abnormal NCS wrists. Mixed model analysis showed that subclinical neuropathy was associated with enlarged CSA, but the other demographic variables (gender, age and body mass index and occupational categories) were not. Our findings support the use of both patient symptoms and NCS to define normal subjects during further studies. In addition, enlarged CSA within asymptomatic individuals should raise concern for subclinical median neuropathy.

Home-based nerve stimulation to enhance effects of motor training in patients in the chronic phase after stroke: a proof-of-principle study

BACKGROUND

Somatosensory stimulation in the form of repetitive peripheral nerve stimulation (RPSS) is a promising strategy to improve motor function of the upper limb in chronic stroke. Home-based RPSS may be an alternative to hospital-based RPSS.

OBJECTIVES

To investigate the feasibility and safety of an innovative program of home-based RPSS combined with motor training and to collect preliminary data on the efficacy of this program to enhance hand motor function in patients in the chronic phase after stroke.

METHODS

Twenty patients were randomized to either active or sham RPSS associated with daily motor training performed at home over 4 consecutive weeks. All the patients were able to perform tasks of the Jebsen-Taylor Test (JTT). The primary outcome measures were feasibility, evaluated by self-reported compliance with the intervention, and safety (adverse events). Secondary outcomes comprised improvements in hand function in the JTT after end of treatment and after a 4-month follow-up period.

RESULTS

There were no relevant adverse events. Compliance with RPSS and motor training was significantly greater in the active group than in the sham group. Upper extremity performance improved significantly more in the active group compared with the sham group at the end of treatment. This difference remained significant 4 months later, even when differences in compliance with motor training were considered.

CONCLUSIONS

Home-based active RPSS associated with motor training was feasible, was safe, and led to long-lasting enhancement of paretic arm performance in the chronic phase after stroke for those who can perform the JTT. These results point to the need for an efficacy trial.

Sonography of the median nerve in CMT1A, CMT2A, CMTX, and HNPP

INTRODUCTION

In this study we compare the ultrasound features in the median nerve in patients with different types of Charcot-Marie-Tooth (CMT) disease and hereditary neuropathies with liability to pressure palsies (HNPP) as a typical entrapment neuropathy.

METHODS

Median nerve ultrasound and conduction studies were performed in patients with CMT1A (n = 12), MFN2-associated CMT2A (n = 7), CMTX (n = 5), and HNPP (n = 5), and in controls (n = 28).

RESULTS

Median nerve cross-sectional area (CSA) was significantly increased in CMT1A, whereas, in axonal CMT2A, fascicle diameter (FD) was enlarged. CSA correlated with nerve conduction slowing in CMT1A and with axonal loss, as shown by motor and sensory nerve amplitudes in both CMT1A and CMT2A. A relatively low wrist-to-forearm-ratio (WFR <0.8) or a relatively high WFR (>1.8) appeared to be unlikely in MFN2 and Cx32 mutations of CMT2A and CMTX, respectively.

CONCLUSION

Differences in CSA, FD, and WFR of the median nerve can be helpful in defining subtypes of hereditary neuropathies.

Motor contingency learning and infants with Spina Bifida

Infants with Spina Bifida (SB) were compared to typically developing infants (TD) using a conjugate reinforcement paradigm at 6 months-of-age (n = 98) to evaluate learning, and retention of a sensory-motor contingency. Analyses evaluated infant arm-waving rates at baseline (wrist not tethered to mobile), during acquisition of the sensory-motor contingency (wrist tethered), and immediately after the acquisition phase and then after a delay (wrist not tethered), controlling for arm reaching ability, gestational age, and socioeconomic status. Although both groups responded to the contingency with increased arm-waving from baseline to acquisition, 15% to 29% fewer infants with SB than TD were found to learn the contingency depending on the criterion used to determine contingency learning. In addition, infants with SB who had learned the contingency had more difficulty retaining the contingency over time when sensory feedback was absent. The findings suggest that infants with SB do not learn motor contingencies as easily or at the same rate as TD infants, and are more likely to decrease motor responses when sensory feedback is absent. Results are discussed with reference to research on contingency learning in infants with and without neurodevelopmental disorders, and with reference to motor learning in school-age children with SB.

The functional role of the cerebellum in visually guided tracking movement

We propose a new method to provide a functional interpretation of motor commands (i.e., muscle activities) and their relationship to movement kinematics. We evaluated our method by analyzing the motor commands of normal controls and patients with cerebellar disorders for visually guided tracking movement of the wrist joint. Six control subjects and six patients with cerebellar disorders participated in this study. We asked the subjects to perform visually guided smooth tracking movement of the wrist joint with a manipulandum, and recorded the movements of the wrist joint and activities of the four wrist prime movers with surface electrodes. We found a symmetric relationship between the second-order linear equation of motion for the wrist joint and the linear sum of activities of the four wrist prime movers. The symmetric relationship determined a set of parameters to characterize the muscle activities and their similarity to the components of movement kinematics of the wrist joint. We found that muscle activities of the normal controls encoded both the velocity and the position of the moving target, resulting in precise tracking of the target. In contrast, muscle activities of the cerebellar patients were characterized by a severer impairment for velocity control and more dependence on position control, resulting in poor tracking of the smoothly moving target with many step-like awkward movements. Our results suggest that the cerebellum plays an important role in the generation of motor commands for smooth velocity and position control.

Sheet fitting palsy

A 73-year-old woman developed an acute thrombosis of a persistent median artery following a Sisyphean struggle with a poorly fitted bedsheet. Ultrasound was able to diagnose the problem in a case where precise localization by electrodiagnostic testing was difficult.

Intermittently increased repetitive work intensity and neuromuscular function in the cold

This study evaluated whether cold-induced deterioration in neuromuscular function can be restored by intermittently increasing the workload. We examined the level of muscular strain, agonist-antagonist co-activation, the occurrence of EMG gaps and neuromuscular efficiency in wrist flexor and extensor muscles at 21°C (TN) and 4°C (C(10)) with a 10%MVC workload. During second exposure to 4°C (C(50)) the workload was increased every fourth minute to 50%MVC. The results indicated that muscular strain and co-activation was the highest and the amount of EMG gaps and neuromuscular efficiency the lowest at C(10). By intermittently increasing the workload at C(50) we were able to reduce muscular strain and co-activation (p<0.05) and induce a trend like increase in EMG gaps and enhance neuromuscular efficiency in relation to C(10) (NS). It may be concluded that intermittently increasing the workload, i.e. breaking the monotonous work cycle was able to partially restore neuromuscular function.

The effect of local corticosteroid injection on F-wave conduction velocity and sympathetic skin response in carpal tunnel syndrome

The aim of this study was to evaluate the efficacy of steroid injection for the treatment of the carpal tunnel syndrome (CTS), with F-wave parameters and sympathetic skin response (SSR). Seventeen hands of 10 women patients were treated with local steroid injection with 2-month follow-up. All patients underwent single injection into the carpal tunnel. Response to injection was measured nerve conduction studies (NCSs), median nerve F waves, and SSR before and after treatment. To determine the normal values, 42 hands of 21 healthy women were also studied. There was a significant improvement of sensory and motor nerve conduction values when compared to baseline values (P < 0.01). At the end of follow-up period, the median sensory distal latency and the sensory latency differences between the median and the ulnar nerve were improved 35 and 65%, respectively. The maximum, mean F-wave amplitudes and chronodispersion showed a slight improvement with respect to baseline values and controls, but statistical significance was not achieved after treatment. Although no statistically significant improvements were observed in SSR parameters, slightly decreased amplitudes and increased habituation of SSR were noted at the end of the treatment. The present study shows that the local steroid injection results in improvement in NCSs values, but the F-wave parameters were not effectual in short-term outcome of CTS treatment. These findings suggest that the sensory latency differences between the median and the ulnar wrist-to-digit 4 are better parameters in the median nerve recovery after treatment than the median sensory distal latency. Furthermore, the SSR does not seem to be a sensitive method in follow-up of CTS treatment.

The dual tendon palmaris longus variant causing dynamic median nerve compression in the forearm

This article describes a variant of palmaris longus muscle resulting in median nerve compression in the mid forearm. Although the palmaris longus has several well-documented anomalies, these seldom lead to nerve compression. The dual tendon, central muscle belly variant observed in this case is the first of its kind to be reported causing compressive neuropathy at this level. This is of both anatomical and clinical interest as it reminds surgeons of the anatomical variations of this unique muscle and presents a new mechanism of nerve compression in the forearm.

Externally cued inphase bimanual training enhances preparatory premotor activity

OBJECTIVE

Previous studies have demonstrated that cortical potentials representing motor preparation for visually-cued movements are enhanced following a single session of visually-cued bimanual movement training (BMT). The neuroanatomical sources that contribute to these rapid training-induced adaptations were unclear. To address this, we compared cortical potentials associated with motor preparation for visually-cued (movement-related potential, MRP) and self-paced (Bereitschaftspotential, BP) movements and investigated adaptations of these following BMT.

METHODS

EEG recorded the cued MRP and self-paced BP during two experiments. In experiment one, pre and post self-paced unimanual trials were interspersed with cued inphase BMT. In experiment two, self-paced and visually-cued movement trials were performed to assess the differences between and the contributing neural sources to the cued MRP and self-paced BP.

RESULTS

Inphase BMT does not affect the early BP. Source localization analysis revealed that the preparatory portion of the cued MRP and self-paced BP are generated by the lateral premotor cortex and the supplementary motor area, respectively.

CONCLUSIONS

The early cued MRP and self-paced BP have unique cortical generators and are independently modulated by specific training types.

SIGNIFICANCE

These novel findings have implications for interpreting rapid, single-session, training adaptations previously observed. These cortical potentials may also be useful measurement tools to gauge within-session cortical modulations in response to specific modes of rehabilitative training in the stroke population.