A cut throat: a case of C5-C8 brachial plexus root transection providing evidence of T1 innervation of thumb and finger extensors

The T1 nerve root is not routinely thought of as innervating the extensors of the thumb and fingers. Work by Bertelli and Ghizoni proposed that the pattern of brachial plexus paralysis with intact hand function and thumb and finger extensors traditionally attributed to C5/6/7 root injury is in fact a C5/6/7/8 injury, with only T1 remaining intact - a 'T1 hand'. This case presents a 19-year-old male who was stabbed in the neck; exploratory surgery determined complete transection of the brachial plexus, with only the T1 nerve root remaining intact. Clinical examination demonstrated grade M4 pronation (with pronator quadratus), wrist extension (with extensor carpi ulnaris), thumb and finger extension (with extensor policis longus and brevis, extensor digitorum communis and extensor index proprius), wrist flexion (with palmaris longus), finger flexion (with flexor digitorum superficialis and profundus), thumb flexion (with flexor policis longus), and thenar and hypothenar muscles. Extensor carpi radialis longus and brevis, flexor carpi radialis and flexor carpi ulnaris were paralyzed. Triceps scored M2. This case provides unequivocal evidence that the T1 root provides significant innervation to the extrinsic thumb and finger extensors.

Hand and Wrist Injuries Associated With Application of Physical Restraints: A Systematic Review

While handcuffs and zip ties are common methods of physical restraint used by law enforcement, they have been noted to damage soft tissue and bony structures of the hand and wrist. This paper seeks to characterize the safety of physical restraints by summarizing its effects on hand and wrist function and disability. Relevant studies were gathered through an independent double selection and extraction process using 3 electronic databases (EMBASE, MEDLINE, and CINAHL) from database inception to June 19, 2020. A total of 16 studies involving 807 participants were included. Lesion to the superficial branch of the radial nerve was the most commonly reported injury noted in 82% (42/55) of hands examined. A total of 6% (5/77) of examined hands had bony injury, including 3 radial styloid fractures and 2 scaphoid fractures. Both studies on zip ties noted presence of handcuff neuropathy, with 1 case report documenting severe rapidly progressing ischemic monomelic neuropathy. Overall, the use of handcuffs and zip ties is associated with entrapment neuropathies and bony injury to the hand and wrist. Further studies of higher quality evidence are necessary to understand the effects of physical restraint on hand function and disability.

Analysis of Mechanoreceptors and Free Nerve Endings of the Transverse Carpal Ligament

Background: The treatment of carpal tunnel syndrome (CTS) by sectioning the transverse carpal ligament (TCL) is not exempt from complications. Some nerve branches may be damaged by the incision. The aim of this study is to identify and map the TCL nerve endings, serving as a guide for sectioning this structure in a zone with less nerve ending density. Methods: Ten TCLs were obtained from fresh frozen cadavers. The TCLs were measured, divided into 3 equal bands (radial, central, and ulnar), and submitted to cryostat sectioning. The sections were subjected to immunofluorescence with the protein gene product (PGP) 9.5 and confocal microscopy analysis. Results: All the specimens contained type I and type IV mechanoreceptors. Neural elements occupied 0.695 ± 0.056% of the ligament area. The density of the neural elements was greater in the radial, followed by the ulnar and central bands, with 0.730 ± 0.083%, 0.686 ± 0.009%, and 0.669 ± 0.031%, respectively. Conclusion: The present findings suggest that the region with the least potential for neural element injury during TCL release is the central third near the transition with the ulnar third. When performed distally to proximally with a slight inclination from the radial to the ulnar, this release compromises the lowest nerve element density. Topographically, the proximal limit of the release is the distal wrist crease, while the distal limit is the intersection of Kaplan cardinal line and the axis of the third webspace.

Penetration of the posterior interosseous nerve fibers into the dorsal capsule of the wrist - a new perspective on wrist innervation

The dorsal capsule of the wrist and the DCSS may play a significant role in the conduction of nerve signals transmitted from proprioceptors present in SL to PIN, which is located above the dorsal capsule. Hence, this study aimed to determine if nerve fibers of PIN penetrate inside the dorsal capsule. The dorsal capsules of the wrist were dissected from both sides from 15 cadavers. Eventually, 30 dorsal capsules were dissected. It can be concluded that the PIN nerve fibers penetrate the dorsal capsule of the wrist, as the penetration was noticeable in every part evaluated. The present study proves that afferent fibers from the mechanoreceptors of the SLIL potentially pass through the DCSS and subsequently through the dorsal capsule of the wrist to the PIN. This knowledge can surely be of great use for hand surgeons that perform procedures on the dorsal wrist.

The Window Test: a simple bedside method to detect radial deviation of the wrist commonly seen in posterior interosseous nerve palsy

BACKGROUND

Posterior interosseous nerve palsy (PINP) is a disorder caused by damage to the posterior interosseous nerve, resulting in weak extension of the wrist and fingers as well as radial deviation of the wrist.

METHODS

In this study, a new type of evaluation for PINP was analyzed in hopes of increasing ease of diagnosis and earlier detection of the disorder. The "Window Test" is performed by the examiner laying hands on the ulnar aspect of the patient's pronated forearm while the latter is trying to extend the wrist. A positive test is observed when a gap (window) appears between the examiner's forearm and the patient's hand. Lay people, medical students, residents, and practicing providers were assessed prospectively on their ability to correctly diagnose PINP by observing one hand, both hands, and by using the Window Test.

RESULTS

The Window Test was consistently found to be the most effective method of evaluation as it increased the accuracy of diagnoses in all groups surveyed. Additionally, case studies were performed using the Window Test on patients, further demonstrating the efficacy of the test by confirming wrist radial deviation.

CONCLUSION

The Window Test introduces a reference frame, making it easier to assess wrist radial deviation and offering a simple evaluation that can be administered by virtually anyone. These findings indicate that the implementation of the Window Test will increase the accuracy and effectiveness of PINP diagnosis, thus allowing early diagnosis and better management.

The Neurophysiological Severity of Carpal Tunnel Syndrome Cannot Be Predicted by Median Nerve Cross-Sectional Area and Wrist-to-Forearm Ratio

PURPOSE

The median nerve cross-sectional area at the wrist (CSA) and the wrist-to-forearm ratio of the cross-sectional areas (WFR) are ultrasound parameters used in the diagnosis and grading of carpal tunnel syndrome. This study aimed to determine the diagnostic accuracy of the CSA and WFR as well as to compare their diagnostic value.

METHODS

A retrospective evaluation was conducted of a cohort of 218 patients who had undergone nerve conduction studies (NCSs) and an ultrasound of the median nerve. The examined wrists were classified into an NCS negative and three NCS positive (mild, moderate, and severe) categories. The CSA and WFR were compared across the categories.

RESULTS

The CSA and WFR were significantly smaller in the NCS negative category than in the NCS positive categories. The WFR was significantly smaller in the mild category than in the moderate category. The CSA could not be used to differentiate across the NCS positive categories.

CONCLUSIONS

The CSA and WFR are satisfactorily reliable in detecting carpal tunnel syndrome, but they cannot be considered as surrogate indicators of electrophysiological severity.

Marinacci anastomosis (reverse Martin-Gruber anastomosis): A case report

RATIONALE

The incidence of Martin-Gruber anastomosis ranges from 5% to 34%, which is characterized by crossing over from the median to the ulnar nerve and innervating the first dorsal interosseous, thenar or hypothenar muscles. However, the reverse Martin-Gruber anastomosis, or Marinacci anastomosis, is far less discussed and appears in recent literature.

PATIENT CONCERNS

A 56-year-old man presented to the clinic of a university hospital because of left neck soreness with numbness radiating to the left lateral shoulder. The neck discomfort was aggravated while the neck rotated or tilted to the right.

DIAGNOSIS

Higher compound muscle action potential over the abductor pollicis brevis on elbow stimulation than on the wrist was found during upper limb nerve conduction velocity study. Ulnar to median anastomosis was identified.

INTERVENTION

We performed cervical spine X-ray and electrophysiological examinations and monitored the patient.

OUTCOMES

We identified that this patient had left C5 and C6 subacute radiculopathy with active denervation and left subclinical ulnar sensory neuropathy, and verified the existence of ulnar-to-median anastomosis.

LESSONS

We demonstrated a pure motor ulnar-to-median anastomosis without sensory correspondence and higher CMAP over the abductor pollicis brevis on elbow stimulation of the ulnar nerve than on the wrist. The prevalence might be underestimated in a Chinese population-based published study.

Efficacy of Hyalase Hydrodissection in the Treatment of Carpal Tunnel Syndrome: A Randomized, Double-Blind, Controlled, Clinical Trial

BACKGROUND

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy, which results from median nerve compression. A lot of nonsurgical modalities are available for the management of mild to moderate situations. Local Hyalase hydrodissection (HD) of the entrapped median nerve could offer a desirable sustained symptom alleviation.

OBJECTIVES

To evaluate the clinical efficacy of Hyalase/saline solution carpal tunnel HD on pain, functional status, and nerve conduction in patients with CTS.

STUDY DESIGN

A randomized, double-blinded trial.

SETTING

Anesthesia, pain, and rheumatology clinics in a university hospital.

METHODS

Patients: 60 patients with CTS (> 6 months' duration).

INTERVENTION

patients were allocated equally into either group 1 (HD with Hyalase + 10 mL saline solution injection), or group 2 (HD with 10 mL saline solution only).

MEASUREMENTS

assessment of pain using Visual Analog Scale (VAS), functional disability (FD) score, and nerve conduction studies before injection, and over 6 months after injection. Nerve conduction parameters before injection and postinjection by the end of 3 and 6 months were evaluated as well.

RESULTS

Statistically significant lower postinjection values of VAS (1 ± 1.8, 2 ± 1.1, 2 ± 1.2, 2 ± 1.1) in group 1 versus (2 ± 1.2, 3 ± 1.7, 4 ± 1.5, 5 ± 2.6) in group 2 by the end of the first week, and the first, third, and sixth months, and significantly lower FD scores (15.3 ± 1.2, 13 ± 1.3, 10.2 ± 1.3, 10.2 ± 1.3) in group 1 versus (17.5 ± 1.8, 16.6 ± 2.8, 19.4 ± 3.2, 21.2 ± 2.5) in group 2 during the same time intervals. Nerve conduction study parameters have shown significantly higher velocity and lower latency in the Hyalase group than in the saline solution group by the 3 and 6 month follow-up.

LIMITATION

We suggest a longer period could be reasonable.

CONCLUSIONS

Carpal tunnel HD with Hyalase with saline solution is considered as an efficient technique offering a rapid onset of pain relief and functional improvements, and better median nerve conduction in patients with CTS over 6 months follow-up duration.

KEY WORDS

Carpal tunnel syndrome, Hyalase, median nerve hydrodissection.

Accuracy of Carpal Tunnel Injection: A Prospective Evaluation of 756 Patients

Background: Corticosteroid injection into the carpal tunnel is both a diagnostic test and a therapeutic modality in the treatment of carpal tunnel syndrome. Many injection techniques are described in the literature. Improper placement of injection may result in damage to neurovascular structures in the carpal canal or decrease efficacy of the test and/or therapy. The purpose of this study is to determine if carpal tunnel injection using anatomic landmarks is reproducible and safe. A review of the senior author's injection technique is presented. Methods: Over 8 years, there were 756 attempted placements of a 25-gauge needle into the carpal tunnel in a simulated carpal tunnel injection prior to open carpal tunnel release. The needle was inserted at the wrist crease, just ulnar to palmaris longus. Open carpal tunnel release was subsequently performed, and position of the needle was recorded. Results: In 572 patients (75.7%), the needle was found to be in the carpal tunnel without penetration of contents. The needle was in the carpal tunnel but piercing the median nerve in 66 attempts (8.7%). The carpal tunnel was missed in 118 attempts (15.6%). Conclusions: This is the largest study looking at accuracy of carpal tunnel injection using anatomic landmarks. Our injection accuracy (75.7%) is less than reported in previous studies, which note 82% to 100% accuracy using the same injection technique. This may indicate that carpal tunnel injection is less reliable than previously thought. Safety of carpal tunnel injection remains an important concern. The median nerve was penetrated in 8.7% of attempts.

Local-to-distant development of the cerebrocerebellar sensorimotor network in the typically developing human brain: a functional and diffusion MRI study

Sensorimotor function is a fundamental brain function in humans, and the cerebrocerebellar circuit is essential to this function. In this study, we demonstrate how the cerebrocerebellar circuit develops both functionally and anatomically from childhood to adulthood in the typically developing human brain. We measured brain activity using functional magnetic resonance imaging while a total of 57 right-handed, blindfolded, healthy children (aged 8-11 years), adolescents (aged 12-15 years), and young adults (aged 18-23 years) (n = 19 per group) performed alternating extension-flexion movements of their right wrists in precise synchronization with 1-Hz audio tones. We also collected their diffusion MR images to examine the extent of fiber maturity in cerebrocerebellar afferent and efferent tracts by evaluating the anisotropy-sensitive index of hindrance modulated orientational anisotropy (HMOA). During the motor task, although the ipsilateral cerebellum and the contralateral primary sensorimotor cortices were consistently activated across all age groups, the functional connectivity between these two distant regions was stronger in adults than in children and adolescents, whereas connectivity within the local cerebellum was stronger in children and adolescents than in adults. The HMOA values in cerebrocerebellar afferent and efferent tracts were higher in adults than in children (some were also higher than in adolescents). The results indicate that adult-like cerebrocerebellar functional coupling is not completely achieved during childhood and adolescence, even for fundamental sensorimotor brain function, probably due to anatomical immaturity of cerebrocerebellar tracts. This study clearly demonstrated the principle of "local-to-distant" development of functional brain networks in the human cerebrocerebellar sensorimotor network.

Comparison of Convolutive Kernel Compensation and Non-Negative Matrix Factorization of Surface Electromyograms

We compared non-negative matrix factorization (NMF) and convolution kernel compensation techniques for high-density electromyogram decomposition. The experimental data were recorded from nine healthy persons during controlled single degree of freedom (DOF) wrist flexion-extension, supination-pronation, and ulnar-radial deviation movements. We assembled the identified motor units and NMF components into three groups. Those active mostly during the first and the second movement direction per DOF were placed in the G1 and G3 groups, respectively. The remaining components were nonspecific for movement direction and were placed in the G2 group. In ulnar and radial deviation, the relative energies of identified cumulative motor unit spike trains (CSTs) and NMF components were similarly distributed among the groups. In other two movement types, the energy of NMF components in the G2 group was significantly larger than the energy of CSTs. We further performed a coherence analysis between CSTs and sums of NMF components in each group. Both decompositions demonstrated a solid match, but only at frequencies <3 Hz. At higher frequencies, the coherence hardly exceeded the value of 0.5. Potential reasons for these discrepancies include the negative impact of motor unit action potential shapes and noise on NMF decomposition.

Anatomical variations of the median nerve and of the vascular-nervous structures at the wrist

Three cases of anatomical variation of the median nerve at the wrist found during our surgical activity led us to take the opportunity to expose anatomical variations by reviewing already published reviews. Consequently, on the basis of anatomical studies, clinical reports and imaging, as a result of careful examination of the published literature, it has been observed that the interventions in such anatomical area must take into account these variations. In particular, the most performed procedure is the lysis of the transverse carpal ligament (TCL), which is not free from complications. In our opinion it is therefore necessary, in order to avoid the complications of the nervous, vascular and tendinous sections, to use some specific technical procedures.

Variability in common synaptic input to motor neurons modulates both force steadiness and pegboard time in young and older adults

KEY POINTS

The fluctuations in force during a steady isometric contraction (force steadiness) are associated with oscillations in common synaptic input to the involved motor neurons. Decreases in force steadiness are associated with increases in pegboard times in older adults, although a mechanism for this link has not been established. We used a state-space model to estimate the variability in common synaptic input to motor neurons during steady, isometric contractions. The estimate of common synaptic input was derived from the discharge times of motor units as recorded with high-density surface electrodes. We found that the variability in common synaptic input to motor neurons modulates force steadiness for young and older adults, as well as pegboard time for older adults.

ABSTRACT

We investigated the associations between grooved pegboard times, force steadiness (coefficient of variation for force) and variability in an estimate of the common synaptic input to motor neurons innervating the wrist extensor muscles during steady contractions performed by young and older adults. The discharge times of motor units were derived from recordings obtained with high-density surface electrodes when participants performed steady isometric contractions at 10% and 20% of maximal voluntary contraction force. The steady contractions were performed with a pinch grip and wrist extension, both independently (single action) and concurrently (double action). The variance in common synaptic input to motor neurons was estimated with a state-space model of the latent common input dynamics. There was a statistically significant association between the coefficient of variation for force during the steady contractions and the estimated variance in common synaptic input in young (r2  = 0.31) and older (r2  = 0.39) adults, although not between either the mean or the coefficient of variation for interspike interval of single motor units with the coefficient of variation for force. Moreover, the estimated variance in common synaptic input during the double-action task with the wrist extensors at the 20% target was significantly associated with grooved pegboard time (r2  = 0.47) for older adults but not young adults. These findings indicate that longer pegboard times of older adults were associated with worse force steadiness and greater fluctuations in the estimated common synaptic input to motor neurons during steady contractions.

Somatotopic Mapping of the Developing Sensorimotor Cortex in the Preterm Human Brain

In the mature mammalian brain, the primary somatosensory and motor cortices are known to be spatially organized such that neural activity relating to specific body parts can be somatopically mapped onto an anatomical "homunculus". This organization creates an internal body representation which is fundamental for precise motor control, spatial awareness and social interaction. Although it is unknown when this organization develops in humans, animal studies suggest that it may emerge even before the time of normal birth. We therefore characterized the somatotopic organization of the primary sensorimotor cortices using functional MRI and a set of custom-made robotic tools in 35 healthy preterm infants aged from 31 + 6 to 36 + 3 weeks postmenstrual age. Functional responses induced by somatosensory stimulation of the wrists, ankles, and mouth had a distinct spatial organization as seen in the characteristic mature homunculus map. In comparison to the ankle, activation related to wrist stimulation was significantly larger and more commonly involved additional areas including the supplementary motor area and ipsilateral sensorimotor cortex. These results are in keeping with early intrinsic determination of a somatotopic map within the primary sensorimotor cortices. This may explain why acquired brain injury in this region during the preterm period cannot be compensated for by cortical reorganization and therefore can lead to long-lasting motor and sensory impairment.

Task- and domain-specific modulation of functional connectivity in the ventral and dorsal object-processing pathways

A whole-brain network of regions collectively supports the ability to recognize and use objects-the Tool Processing Network. Little is known about how functional interactions within the Tool Processing Network are modulated in a task-dependent manner. We designed an fMRI experiment in which participants were required to either generate object pantomimes or to carry out a picture matching task over the same images of tools, while holding all aspects of stimulus presentation constant across the tasks. The Tool Processing Network was defined with an independent functional localizer, and functional connectivity within the network was measured during the pantomime and picture matching tasks. Relative to tool picture matching, tool pantomiming led to an increase in functional connectivity between ventral stream regions and left parietal and frontal-motor areas; in contrast, the matching task was associated with an increase in functional connectivity among regions in ventral temporo-occipital cortex, and between ventral temporal regions and the left inferior parietal lobule. Graph-theory analyses over the functional connectivity data indicated that the left premotor cortex and left lateral occipital complex were hub-like (exhibited high betweenness centrality) during tool pantomiming, while ventral stream regions (left medial fusiform gyrus and left posterior middle temporal gyrus) were hub-like during the picture matching task. These results demonstrate task-specific modulation of functional interactions among a common set of regions, and indicate dynamic coupling of anatomically remote regions in task-dependent manner.

Movement-related beta oscillations show high intra-individual reliability

Oscillatory activity in the beta frequency range (15-30Hz) recorded from human sensorimotor cortex is of increasing interest as a putative biomarker of motor system function and dysfunction. Despite its increasing use in basic and clinical research, surprisingly little is known about the test-retest reliability of spectral power and peak frequency measures of beta oscillatory signals from sensorimotor cortex. Establishing that these beta measures are stable over time in healthy populations is a necessary precursor to their use in the clinic. Here, we used scalp electroencephalography (EEG) to evaluate intra-individual reliability of beta-band oscillations over six sessions, focusing on changes in beta activity during movement (Movement-Related Beta Desynchronization, MRBD) and after movement termination (Post-Movement Beta Rebound, PMBR). Subjects performed visually-cued unimanual wrist flexion and extension. We assessed Intraclass Correlation Coefficients (ICC) and between-session correlations for spectral power and peak frequency measures of movement-related and resting beta activity. Movement-related and resting beta power from both sensorimotor cortices was highly reliable across sessions. Resting beta power yielded highest reliability (average ICC=0.903), followed by MRBD (average ICC=0.886) and PMBR (average ICC=0.663). Notably, peak frequency measures yielded lower ICC values compared to the assessment of spectral power, particularly for movement-related beta activity (ICC=0.386-0.402). Our data highlight that power measures of movement-related beta oscillations are highly reliable, while corresponding peak frequency measures show greater intra-individual variability across sessions. Importantly, our finding that beta power estimates show high intra-individual reliability over time serves to validate the notion that these measures reflect meaningful individual differences that can be utilised in basic research and clinical studies.

Bifid median nerve and carpal tunnel syndrome: an uncommon anatomical variation

Dear sir, one of the most common entrapment neuropathy syndromes in clinical practice is "Entrapment of median nerve in carpal tunnel" also called "Carpal tunnel syndrome (CTS)" (Aydin et al., 2007; Huisstede et al., 2010). This syndrome is caused by entrapment of the median nerve in the wrist (Preston and Shapiro, 2005) when the pressure increases in the carpal tunnel. A high division of the median nerve proximal to the carpal tunnel, also known as a bifid median nerve, is a rare anatomic variation that may be associated with CTS and with persistent median vessels (Lanz, 1977). This anatomic variation has an incidence of 0,8% to 2,3% in patients with CTS. Lanz (1977) has characterized this anatomic condition of the median nerve in the carpal tunnel. These anatomic variants have been classified into four groups: - Group 0: extraligamentous thenar branch (standard anatomy); - Group 1: variations of the course of the thenar branch; - Group 2: accessory branches at the distal portion of the carpal tunnel; - Group 3: divided or duplicated median nerve inside the carpal tunnel; - Group 4: accessory branches proximal to the carpal tunnel. During dissection of the wrist performed for the treatment of a CTS under local anesthesia, we found an anatomical variation of the median nerve that was divided in two branches inside the carpal tunnel (Group 3 of Lanz Classification) and in which its radial branch passed through its own compartment. The two parts of the nerve seems to be unequal in size (Fig. 1). Moreover the nerve passed in carpal tunnel associated with a median artery, so we classified this variation in the group 3b of Lanz Classification (Fig. 2). The persistence of median artery coexisting with a bifid median nerve has been widely reported in surgical literature (Lanz, 1977; Barbe et al., 2005). Before surgical intervention clinical evaluation of patient and electrophysiological examination showed no differences compared to a non bifid median nerve entrapment syndrome. In conclusion the bifid median nerve may facilitate compression of median nerve in the carpal tunnel because of its increased cross sectional area even if it has no electrophysiological or clinical differential diagnosis in case of CTS. The aim of this letter is aware the physicians in order to borne in mind the possible presence of a median nerve variation during dissection of carpal tunnel in order to avoid the damage of this non common anatomical structures.

Wrist denervation of the posterior interosseous nerve through a volar approach: a new technique with anatomical considerations

PURPOSE

Full or selective wrist denervation is an effective treatment for chronic wrist pain. In this cadaveric study, a volar approach for prophylactic denervation of the posterior interosseous nerve (PIN) and the anterior interosseous nerve (AIN) was assessed, which can simultaneously be performed during volar approaches for distal radius fracture fixation or in combination with metalwork removal.

MATERIALS AND METHODS

In total 40 adult upper limbs, embalmed using Thiel's method, were investigated. Group 1 included 20 limbs of which the distances between AIN and PIN to the ulnar margin of radius were measured at levels 6, 8 and 10 cm proximal to the styloid process and the distance radial styloid process to proximal border of pronator quadratus which might be useful as an intraoperative landmark. Subsequently further additional 20 adult limbs (group 2) were used. Transection of the PIN via this volar approach at the evaluated best level of step 1 was performed and evaluated by dissection via a dorsal approach.

RESULTS

In group 1, the PIN runs within the interosseous membrane, from the ulnar border of the radius, 6.4 mm (SD 2.66) at 6 cm, 8.4 mm (SD 2.28) at 8 cm and 3.75 mm (SD 5.46) at 10 cm proximal to the radial styloid. The AIN runs within the interosseous membrane, from the ulna edge of the radius, 7.5 mm (SD 2.4) at 6 cm, 7.3 mm (SD 1.95) at 8 cm and 2.35 mm (3.42) at 10 cm proximal to the radial styloid. AIN and PIN were in close proximity at the 8-cm level which equals a 1-cm distance proximal to the pronator quadratus border. Group 2 showed a successful transection of the PIN through a single volar surgical approach in additional 18 out of 20 adult upper limbs.

CONCLUSIONS

This study shows the local anatomy of the PIN, allowing denervation via a volar approach.

Radical Wrist Denervation and Preliminary Results

Denervation is a well recognized procedure to treat degenerative or posttraumatic joint conditions, especially in cases where pain is a significant impediment to function even in the presence of stable and supple joint. However, this procedure currently is not as widely used for wrist surgeries as it merits. Denervation procedure obeys all-or-none phenomenon and we believe that even a few residual intact sensory fibers are able to transmit severe pain sensation and therefore every attempt should be made to target all the sensory supply to the wrist joint. In the present article a modified and radical technique using a single dorsal incision is proposed to address the hypothetical pitfalls of leaving undivided sensitive branches. Preliminary results of 21 cases operated on by this method are presented.

Long-Term Results of Tendon Transfers in Radial and Posterior Interosseous Nerve Paralysis

Eighteen cases of tendon transfer for isolated radial or posterior interosseous nerve palsy have been carried out in our unit over a period of 21 years. Fifteen patients were reviewed with a mean follow-up of 9.5 years. Nine had sustained high and six low radial nerve injury. We achieved 11 excellent, two good, one fair and one bad result. The main problems were loss of power of gripping and the occurrence of radial deviation, particularly in patients with flexor carpi ulnaris transfer to the extensor digitorum communis. During this time, our technique has evolved, including changes of the tendons transferred. Our final preference is a modified Tsuge procedure, using the pronator teres to restore extension of the wrist, the flexor carpi radialis for extension of the fingers and the palmaris longus for extension of the thumb. Abduction of the thumb is restored by a tenodesis of the abductor pollicis longus to the brachioradialis. This review justifies the final policy, in particular the preservation of flexor carpi ulnaris to maintain wrist stability and flexion.

Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis

Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS.

Development of Kinematic Graphs of Median Nerve during Active Finger Motion: Implications of Smartphone Use

Background

Certain hand activities cause deformation and displacement of the median nerve at the carpal tunnel due to the gliding motion of tendons surrounding it. As smartphone usage escalates, this raises the public’s concern whether hand activities while using smartphones can lead to median nerve problems.

Objective

The aims of this study were to 1) develop kinematic graphs and 2) investigate the associated deformation and rotational information of median nerve in the carpal tunnel during hand activities.

Methods

Dominant wrists of 30 young adults were examined with ultrasonography by placing a transducer transversely on their wrist crease. Ultrasound video clips were recorded when the subject performing 1) thumb opposition with the wrist in neutral position, 2) thumb opposition with the wrist in ulnar deviation and 3) pinch grip with the wrist in neutral position. Six still images that were separated by 0.2-second intervals were then captured from the ultrasound video for the determination of 1) cross-sectional area (CSA), 2) flattening ratio (FR), 3) rotational displacement (RD) and 4) translational displacement (TD) of median nerve in the carpal tunnel, and these collected information of deformation, rotational and displacement of median nerve were compared between 1) two successive time points during a single hand activity and 2) different hand motions at the same time point. Finally, kinematic graphs were constructed to demonstrate the mobility of median nerve during different hand activities.

Results

Performing different hand activities during this study led to a gradual reduction in CSA of the median nerve, with thumb opposition together with the wrist in ulnar deviation causing the greatest extent of deformation of the median nerve. Thumb opposition with the wrist in ulnar deviation also led to the largest extent of TD when compared to the other two hand activities of this study. Kinematic graphs showed that the motion pathways of median nerve during different hand activities were complex.

Conclusion

We observed that the median nerve in the carpal tunnel was rotated, deformed and displaced during the hand activities that people may be performed when using a smartphone, suggesting an increased risk of carpal tunnel syndrome (CTS). In addition, the kinematic graphs of median nerve developed in the present study provide new clues for further studies on the pathophysiology of CTS, and alerting smartphone users to establish proper postural habits when using handheld electronic devices.

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.