ABSTRACT
BACKGROUND: Peripheral nerve stimulation with a train-of-four (TOF) pattern can be used intraoperatively to evaluate the depth of neuromuscular block and confirm recovery from neuromuscular blocking agents (NMBAs). Quantitative monitoring can be challenging in infants and children due to patient size, equipment technology, and limited access to monitoring sites. Although the adductor pollicis muscle is the preferred site of monitoring, the foot is an alternative when the hands are unavailable. However, there is little information on comparative evoked neuromuscular responses at those 2 sites. METHODS: Pediatric patients undergoing inpatient surgery requiring NMBA administration were studied after informed consent. Electromyographic (EMG) monitoring was performed simultaneously in each participant at the hand (ulnar nerve, adductor pollicis muscle) and the foot (posterior tibial nerve, flexor hallucis brevis muscle). RESULTS: Fifty patients with a mean age of 3.0 ± standard deviation (SD) 2.9 years were studied. The baseline first twitch amplitude (T1) of TOF at the foot (12.46 mV) was 4.47 mV higher than at the hand (P <.0001). The baseline TOF ratio (TOFR) before NMBA administration and the maximum TOFR after antagonism with sugammadex were not different at the 2 sites. The onset time until the T1 decreased to 10% or 5% of the baseline value (T1) was delayed by approximately 90 seconds (both P =.014) at the foot compared with the hand. The TOFR at the foot recovered (TOFR ≥0.9) 191 seconds later than when this threshold was achieved at the hand (P =.017). After antagonism, T1 did not return to its baseline value, a typical finding with EMG monitoring, but the fractional recovery (maximum T1 at recovery divided by the baseline T1) at the hand and foot was not different, 0.81 and 0.77, respectively (P =.68). The final TOFR achieved at recovery was approximately 100% and was not different between the 2 sites. CONCLUSIONS: Although this study in young children demonstrated the feasibility of TOF monitoring, interpretation of the depth of neuromuscular block needs to consider the delayed onset and the delayed recovery of TOFR at the foot compared to the hand. The delay in achieving these end points when monitoring the foot may impact the timing of tracheal intubation and assessment of adequate recovery of neuromuscular block to allow tracheal extubation (ie, TOFR ≥0.9).
Subject(s)
Electromyography , Muscle, Skeletal , Neuromuscular Blockade , Humans , Male , Female , Electromyography/methods , Prospective Studies , Child, Preschool , Muscle, Skeletal/innervation , Muscle, Skeletal/physiology , Child , Neuromuscular Blockade/methods , Infant , Foot , Electric Stimulation , Ulnar Nerve , Hand/innervation , Neuromuscular Blocking Agents/administration & dosage , Neuromuscular Monitoring/methods , Tibial NerveABSTRACT
Neurogenic thoracic outlet syndrome is a complex condition and is commonly misunderstood. Historically, much of this confusion has been because of its grouping with other diagnoses that have little in common other than anatomic location. Modern understanding emphasizes the role of small unmyelinated C type pain and sympathetic fibers. Diagnosis is primarily clinical, after ruling out other common conditions. Hand therapy is usually the first-line treatment with variable success. Local anesthetic, botulinum toxins, or steroid injections can aid in diagnosis and offer short-term relief. Although surgery can yield reliable results, it is technically challenging, and the preferred surgical approach is a matter of debate. Despite limitations in diagnosis and treatment, recognition and successful treatment of this condition can be highly impactful for the patient.
Subject(s)
Thoracic Outlet Syndrome , Thoracic Outlet Syndrome/surgery , Thoracic Outlet Syndrome/diagnosis , Humans , Decompression, Surgical/methods , Hand/innervation , Hand/surgeryABSTRACT
Errors of touch localization after hand nerve injuries are common, and their measurement is important for evaluating functional recovery. Available empirical accounts have significant methodological limitations, however, and a quantitatively rigorous and detailed description of touch localization in nerve injury is lacking. Here, we develop a new method of measuring touch localization and evaluate its value for use in nerve injury. Eighteen patients with transection injuries to the median/ulnar nerves and 33 healthy controls were examined. The hand was blocked from the participant's view and points were marked on the volar surface using an ultraviolet (UV) pen. These points served as targets for touch stimulation. Two photographs were taken, one with and one without UV lighting, rendering targets seen and unseen, respectively. The experimenter used the photograph with visible targets to register their locations, and participants reported the felt position of each stimulation on the photograph with unseen targets. The error of localization and its directional components were measured, separate from misreferrals-errors made across digits, or from a digit to the palm. Nerve injury was found to significantly increase the error of localization. These effects were specific to the territory of the repaired nerve and showed considerable variability at the individual level, with some patients showing no evidence of impairment. A few patients also made abnormally high numbers of misreferrals, and the pattern of misreferrals in patients differed from that observed in healthy controls.NEW & NOTEWORTHY We provide a more rigorous and comprehensive account of touch localization in nerve injury than previously available. Our results show that touch localization is significantly impaired following median/ulnar nerve transection injuries and that these impairments are specific to the territory of the repaired nerve(s), vary considerably between patients, and can involve frequent errors spanning between digits.
Subject(s)
Touch Perception , Touch , Humans , Touch/physiology , Hand/innervation , Median Nerve , Ulnar Nerve/physiologyABSTRACT
INTRODUCTION/AIMS: The reason for the variable rate of progression of patients with carpal tunnel syndrome (CTS) to thenar muscles impairment is not fully understood. The aim of this study was to evaluate the occurrence of ultrasound signs of recurrent motor branch (RMB) neuropathy in patients with CTS and to correlate imaging findings with clinical and electrophysiological data. METHODS: Two cohorts were recruited, one consisting of CTS patients with electrodiagnostic evidence of prolonged median distal motor latency from wrist to thenar eminence and another consisting of sex- and age-matched healthy controls. Ultrasound reliability of RMB measurement was assessed by the calculation of the interclass correlation coefficient (ICC). Patients were evaluated with electrodiagnostic tests and asked to complete the Boston Carpal Tunnel Questionnaire. The difference between the RMB diameter in patients and controls was analyzed using a t test. Correlations between RMB diameter and other parameters were assessed using linear mixed models. RESULTS: 46 hands from 32 patients with CTS and 50 hands from 50 controls were evaluated. The intra- and interobserver agreements in RMB measurement were very good (ICC = 0.84; 95% confidence interval [CI], 0.75 to 0.90) and good (ICC = 0.79; 95% CI, 0.69 to 0.87). The RMB diameter was significantly larger in patients than in controls (P < .0001). No significant correlation was found between the RMB diameter and other variables, except for BMI and median nerve cross-sectional area. DISCUSSION: Ultrasound is reliable in identifying the RMB and characterizing its abnormalities. In this patient cohort, ultrasound allowed for detection of definite signs of RMB compression neuropathy.
Subject(s)
Carpal Tunnel Syndrome , Neuritis , Humans , Carpal Tunnel Syndrome/diagnostic imaging , Reproducibility of Results , Median Nerve/diagnostic imaging , Ultrasonography/methods , Hand/innervationABSTRACT
INTRODUCTION: The superficial branch of the radial nerve (SBRN) and the lateral antebrachial cutaneous nerve (LACN) are sensory nerves coursing within the forearm in a close relationship. This high degree of overlap and eventual communication between the nerves is of great surgical importance. The aim of our study is to identify the communication pattern and overlap of the nerves, to localize the position of this communication in relation to a bony landmark, and to specify the most common communication patterns. MATERIALS AND METHODS: One hundred and two adult formalin-fixed cadaveric forearms from 51 cadavers of Central European origin were meticulously dissected. The SBRN, as well as the LACN, were identified. The morphometric parameters concerning these nerves, as well as their branches and connections, were measured with a digital caliper. RESULTS: We have described the primary (PCB) and secondary communications (SCB) between the SBRN and the LACN and their overlap patterns. One hundred and nine PCBs were found in 75 (73.53%) forearms of 44 (86.27%) cadavers and fourteen SCBs in eleven hands (10.78%) of eight cadavers (15.69%). Anatomical and surgical classifications were created. Anatomically, the PCBs were classified in three different ways concerning: (1) the role of the branch of the SBRN within the connection; (2) the position of the communicating branch to the SBRN; and (3) the position of the LACN branch involved in the communication to the cephalic vein (CV). The mean length and width of the PCBs were 17.12 mm (ranged from 2.33 to 82.96 mm) and 0.73 mm (ranged from 0.14 to 2.01 mm), respectively. The PCB was located proximally to the styloid process of the radius at an average distance of 29.91 mm (ranged from 4.15 to 97.61 mm). Surgical classification is based on the localization of the PCBs to a triangular zone of the SBRN branching. The most frequent branch of the SBRN involved in the communication was the third (66.97%). Due to the frequency and position of the PCB with the third branch of the SBRN, the danger zone was predicted. According to the overlap between the SBRN and the LACN, we have divided 102 forearms into four types: (1) no overlap; (2) present overlap; (3) pseudo-overlap; and (4) both present and pseudo-overlap. Type 4 was the most common. CONCLUSION: The patterns of communicating branch arrangements appeared to be not just a rare phenomenon or variation, but rather a common situation highlighting clinical importance. Due to the close relationship and connection of these nerves, there is a high probability of simultaneous lesion.
Subject(s)
Forearm , Radial Nerve , Adult , Humans , Forearm/innervation , Radial Nerve/anatomy & histology , Radius , Hand/innervation , CadaverABSTRACT
Neuropathy of the digital nerves of the hand are very uncommon. Few studies dealt with spontaneous atraumatic digital nerve palsy. Repetitive micro-traumatisms and anatomical variants were implicated in nerve compression. This case report presents a patient with idiopathic common digital nerve constrictive neuropathy.
Subject(s)
Hand , Peripheral Nerve Injuries , Humans , Hand/innervation , Peripheral Nerves , ParalysisABSTRACT
PURPOSE: Lumbrical muscles of the upper limb belong to the middle group of intrinsic hand muscles. Their anatomical variability has been extensively studied with heterogeneous findings. Therefore, the aim of this study is to provide a systematic review and a meta-analysis of the lumbrical muscles variations in the human hand. METHODS: For this purpose, four major electronic databases were searched to identify eligible studies. Then, all relevant data were extracted, and statistical analysis performed. A new classification of lumbrical muscles variations is proposed to summarize and clearly define all described findings. We included 26 studies, making a total sample of 1340 dissected hands. FINDINGS: The most common variations for each muscle were an accessory belly for the first lumbrical muscle, a variable origin for the second lumbrical muscle, a variable innervation for the third lumbrical muscle and a variable insertion for the fourth lumbrical muscle with the prevalence 3.8%; 7.7%; 12% and 5.8%, respectively. CONCLUSIONS: We believe that results of our statistical analysis are suitable for both hand surgeons and other medical professionals dealing with hand injuries or functional problems in their daily routine.
Subject(s)
Hand , Muscle, Skeletal , Humans , Muscle, Skeletal/innervation , Hand/innervationABSTRACT
We present a patient with Pacinian corpuscle hypertrophy and hyperplasia in the hand and discuss the diagnosis and treatment of this rare condition. A 46-year-old woman presented with radiating pain of the left middle finger. A strong Tinel-like sign was elicited between the index and middle fingers. The patient frequently used mobile phone, with the corner of the phone consistently applying pressure on the palm. The surgery was carried out under the microscope and two enlarged cystic lesions under the epineurium were found in the proper digital nerve. Histologic examination revealed hypertrophied Pacinian corpuscle with normal structure. Postoperatively, her symptoms gradually improved. Preoperative diagnosis of this disease is very difficult. Hand surgeons should keep this disease in mind preoperatively. In our case, we would not have been able to identify multiple hypertrophic Pacinian corpuscles without the microscope. An operating microscope is recommended in a surgery of this nature. Level of Evidence: Level V (Therapeutic).
Subject(s)
Hand , Microsurgery , Pacinian Corpuscles , Peripheral Nerves , Peripheral Nervous System Diseases , Female , Humans , Middle Aged , Fingers/innervation , Fingers/surgery , Hand/innervation , Hand/surgery , Hyperplasia/surgery , Neuroma/surgery , Pacinian Corpuscles/pathology , Pacinian Corpuscles/surgery , Peripheral Nervous System Diseases/etiology , Peripheral Nervous System Diseases/surgery , Hypertrophy/surgery , Peripheral Nerves/surgeryABSTRACT
We report a case of a bilateral glass injury to the wrist with transection of flexor tendons and the ulnar nerve and artery in a 60-year-old male patient. Two days after his accident, we repaired all divided structures, and on the right hand, we added the transfer of the opponens motor branch to the deep terminal division of the ulnar nerve aimed at first dorsal interosseous and adductor pollicis muscle reinnervation. After surgery, the patient was followed over 24 months. Postoperative dynamometry of the hand, which included grasping, key-pinch, subterminal-key-pinch, pinch-to-zoom, and first dorsal interosseous muscle strength, indicated recovery only in the nerve transfer side.
Subject(s)
Nerve Transfer , Ulnar Nerve , Male , Humans , Middle Aged , Ulnar Nerve/surgery , Ulnar Nerve/injuries , Wrist , Hand/innervation , Muscle, Skeletal/surgeryABSTRACT
PURPOSE: The dermatomal distributions of the ulnar and median nerves on the palmar skin of the hand have been studied thoroughly. However, the anatomic course of the median and ulnar cutaneous nerve branches and how they supply the skin of the palm is not well understood. METHODS: The cutaneous branches of the median and ulnar nerves were dissected bilaterally in 9 fresh cadavers injected arterially with green latex. RESULTS: We observed 3 groups of cutaneous nerve branches in the palm of the hand: a proximal row group consisting of long branches that originated proximal to the superficial palmar arch and reached the distal palm, first web space, or hypothenar region; a distal row group consisting of branches originating between the superficial palmar arch and the transverse fibers of the palmar aponeurosis (these nerves had a longitudinal trajectory and were shorter than the branches originating proximal to the palmar arch); and a metacarpophalangeal group, composed of short perpendicular branches originating on the palmar surface of the proper palmar digital nerves at the web space. The radial and ulnar borders of the hand distal to the palmar arch were innervated by short transverse branches arising from the proper digital nerves of the index and little finger. Nerve branches did not perforate the palmar aponeurosis in 16 of 18 cases. CONCLUSIONS: The palm of the hand was consistently innervated by 20-35 mm long cutaneous branches originating proximal to the palmar arch and shorter branches originating distal to the palmar arch. These distal branches were either perpendicular or parallel to the proper palmar digital nerves. CLINICAL RELEVANCE: Transfer of long proximal row branches may present an opportunity to restore sensibility in nerve injuries.
Subject(s)
Hand , Ulnar Nerve , Humans , Ulnar Nerve/anatomy & histology , Hand/innervation , Fingers , Peripheral Nerves , Median Nerve/anatomy & histology , Ulnar Artery , CadaverABSTRACT
PURPOSE: The second palmar interosseous muscle is innervated solely by the ulnar nerve, and second palmar interosseous pinch (2IP) strength may be a good indicator of ulnar nerve motor function. The goal of this study was to describe the 2IP test and establish its normative values, stratified by age, sex, and dominance. METHODS: Volunteers were recruited to participate in this study at various community locations. Patients over the age of 18 years were eligible for this study. Demographic information on all subjects was collected. The volunteers were asked to pinch a hydraulic pinch gauge between the index and middle finger proximal phalanges with the proximal and distal interphalangeal joints flexed and without recruiting the thumb. Three 2IP measurements were taken for each hand. Descriptive statistics and analysis of covariance were performed to determine the effect of age, sex, dominance, and side on 2IP. We analyzed the 2IP strength using the 2IP test across 3 trials to determine whether it was affected by repeated testing. RESULTS: Two hundred thirty-eight patients met the inclusion criteria (45 ± 21 years, 55% women, 87% right-hand dominant). There was no statistically significant difference between dominant and nondominant hands or among the 3 trials. There was a statistically significant correlation between age and 2IP strength ranging between 0.32 and 0.44 kg. Age and sex showed a statistically significant association with 2IP strength, with patients of older age and women having weaker 2IP. CONCLUSIONS: We determined normative values for 2IP strength using a sample from a normal population. More studies are needed to validate these results. CLINICAL RELEVANCE: Second interosseous pinch strength may be a useful tool to assess ulnar nerve function.
Subject(s)
Hand , Muscle Strength , Muscle, Skeletal , Ulnar Nerve , Adult , Female , Humans , Male , Middle Aged , Hand/innervation , Muscle, Skeletal/innervation , Muscle, Skeletal/physiology , Reference Values , Ulnar Nerve/physiology , Aged , Volunteers , Muscle Strength/physiologyABSTRACT
Whether the neural control of manual behaviors differs between the dominant and nondominant hand is poorly understood. This study aimed to determine whether the level of common synaptic input to motor neurons innervating the same or different muscles differs between the dominant and the nondominant hand. Seventeen participants performed two motor tasks with distinct mechanical requirements: an isometric pinch and an isometric rotation of a pinched dial. Each task was performed at 30% of maximum effort and was repeated with the dominant and nondominant hand. Motor units were identified from two intrinsic (flexor digitorum interosseous and thenar) and one extrinsic muscle (flexor digitorum superficialis) from high-density surface electromyography recordings. Two complementary approaches were used to estimate common synaptic inputs. First, we calculated the coherence between groups of motor neurons from the same and from different muscles. Then, we estimated the common input for all pairs of motor neurons by correlating the low-frequency oscillations of their discharge rate. Both analyses led to the same conclusion, indicating less common synaptic input between motor neurons innervating different muscles in the dominant hand than in the nondominant hand, which was only observed during the isometric rotation task. No between-side differences in common input were observed between motor neurons of the same muscle. This lower level of common input could confer higher flexibility in the recruitment of motor units, and therefore, in mechanical outputs. Whether this difference between the dominant and nondominant arm is the cause or the consequence of handedness remains to be determined.NEW & NOTEWORTHY How the neural control of manual behaviors differs between the dominant and nondominant hand remains poorly understood. This study shows that there is less common synaptic input between motor neurons innervating different muscles in the dominant than in the nondominant hand during isometric rotation tasks. This lower level of common input could confer higher flexibility in the recruitment of motor units.
Subject(s)
Functional Laterality , Motor Neurons , Electromyography , Hand/innervation , Humans , Motor Neurons/physiology , Muscle, Skeletal/physiologyABSTRACT
Robotic prostheses controlled by myoelectric signals can restore limited but important hand function in individuals with upper limb amputation. The lack of individual finger control highlights the yet insurmountable gap to fully replacing a biological hand. Implanted electrodes around severed nerves have been used to elicit sensations perceived as arising from the missing limb, but using such extra-neural electrodes to record motor signals that allow for the decoding of phantom movements has remained elusive. Here, we showed the feasibility of using signals from non-penetrating neural electrodes to decode intrinsic hand and finger movements in individuals with above-elbow amputations. We found that information recorded with extra-neural electrodes alone was enough to decode phantom hand and individual finger movements, and as expected, the addition of myoelectric signals reduced classification errors both in offline and in real-time decoding.
Subject(s)
Artificial Limbs , Hand , Amputation, Surgical , Electrodes, Implanted , Electromyography , Hand/innervation , Humans , Movement/physiology , Upper ExtremityABSTRACT
RESUMEN: Nos motivó esta presentación los hallazgos observados en la sala de disección sobre las relaciones de la rama palmar profunda de la arteria ulnar y el ramo profundo del nervio ulnar, las diferentes disposiciones de esta rama, el cruzamiento, cuando existe, entre ambos elementos y las pocas referencias sobre el tema, todo con miras a favorecer el abordaje profundo de la palma de la mano y contribuir al conocimiento del área en donde se practican las neurotomías del ramo profundo del nervio ulnar y/ o sus ramas.
SUMMARY: We are motivated by the findings observed in the dissection room on the relationship between the deep palmar branch of ulnar artery and the deep branch of ulnar nerve, the different dispositions of this branch, the crossing, when it exists, between both elements and the few references on the subject, all with a view to favoring the deep approach to the palm and contributing to the knowledge of the area where neurotomies of the deep branch of ulnar nerve and/or its branches are performed.
Subject(s)
Humans , Ulnar Nerve/anatomy & histology , Ulnar Artery/anatomy & histology , Hand/anatomy & histology , Hand/innervation , Hand/blood supplyABSTRACT
BACKGROUND AND PURPOSE: Fascicular targeting of longitudinal intrafascicular electrode (FAST-LIFE) interface enables hand dexterity with exogenous electrical microstimulation for sensory restoration, custom neural recording hardware, and deep learning-based artificial intelligence for motor intent decoding. The purpose of this technical report from a prospective pilot study was to illustrate magnetic resonance neurography (MRN) mapping of hand and nerve anatomy in amputees and incremental value of MRN over electrophysiology findings in pre-surgical planning of FAST-LIFE interface (robotic hand) patients. MATERIALS AND METHODS: After obtaining informed consent, patients with upper extremity amputations underwent pre-operative 3-T MRN, X-rays, and electrophysiology. MRN findings were correlated with electrophysiology reports. Descriptive statistics were performed. RESULTS: Five patients of ages 21-59 years exhibited 3/5 partial hand amputations, and 2/5 transradial amputations on X-rays. The median and ulnar nerve end bulb neuromas measured 10.1 ± 3.04 mm (range: 5.5-14 mm, median: 10.5 mm) and 10.9 ± 7.64 mm (2-22 mm, 9.75 mm), respectively. The ADC of median and ulnar nerves were increased at 1.64 ± 0.1 × 10-3 mm2/s (range: 1.5-1.8, median: 1.64 × 10-3 mm2/s) and 1.70 ± 0.17 × 10-3 mm2/s (1.49-1.98 × 10-3 mm2/s, 1.65 × 10-3 mm2/s), respectively. Other identified lesions were neuromas of superficial branch of the radial nerve and anterior interosseous nerve. On electrophysiology, 2/5 reports were unremarkable, 2/5 showed mixed motor-sensory neuropathies of median and ulnar nerves along with radial sensory neuropathy, and 1/5 showed sensory neuropathy of lateral cutaneous nerve of the forearm. All patients regained naturalistic sensations and motor control of digits. CONCLUSION: 3-T MRN allows excellent demonstration of forearm and hand nerve anatomy, altered diffusion characteristics, and their neuromas despite unremarkable electrophysiology for pre-surgical planning of the FAST-LIFE (robotic hand) interfaces.
Subject(s)
Neuroma , Robotic Surgical Procedures , Adult , Amputation, Surgical , Artificial Intelligence , Electrodes , Hand/diagnostic imaging , Hand/innervation , Hand/surgery , Humans , Magnetic Resonance Imaging , Middle Aged , Peripheral Nerves/diagnostic imaging , Peripheral Nerves/pathology , Peripheral Nerves/surgery , Pilot Projects , Prospective Studies , Ulnar Nerve/diagnostic imaging , Ulnar Nerve/surgery , Upper Extremity/diagnostic imaging , Upper Extremity/innervation , Upper Extremity/surgery , Young AdultABSTRACT
Schwannomas of the ulnar nerve in the hand are uncommon and those arising from the deep motor branch of the ulnar nerve (DMBUN) are rare. We were able to find only five reports of a schwannoma of the DMBUN. We report a schwannoma arising from DMBUN beyond the Guyon canal and summarise the literature on schwannomas involving the DMBUN. Level of Evidence: Level V (Therapeutic).
Subject(s)
Neurilemmoma , Ulnar Nerve , Forearm , Hand/innervation , Humans , Neurilemmoma/diagnostic imaging , Neurilemmoma/surgery , Ulnar Nerve/surgery , WristABSTRACT
The ulnar nerve originates from the anterior division of the lower trunk of the brachial plexus which continues as the medial cord and gives off branches to the forearm and the hand with motor and sensory fibers. The objective of the current study is to assemble the recognized anatomical variations of the ulnar nerve (UN) and underline their clinical impact. A literature search was undertaken via PubMed database, using the term: "ulnar nerve AND variations." Classical anatomical textbooks were also used for the normal anatomy of the UN. A total of 23 articles met the inclusion criteria, 16 of which are included in this review. Fifty-four additional articles provided useful information according to the aim of this review. Of great interest is the communication between the UN and the radial nerve (RN) in the forearm, as well as the communication between the UN and the median nerve (MN) in both forearm and hand. Furthermore, variations of the UN were observed in the hand and the classification of the UN compression was also described according to the point of the neuropathy. These collecting data are categorized into five tables. Additional aberrations were also included in this review. According to literature, the UN is characterized by numerous variations of its course and branches. Therefore, good knowledge of the normal anatomy is essential. Moreover, the anomalies are of particular importance due to their significant clinical implications and should be taken into consideration by the surgeons during surgical procedures in this region.
Subject(s)
Brachial Plexus , Ulnar Nerve , Brachial Plexus/abnormalities , Forearm , Hand/innervation , Humans , Median Nerve , Ulnar Nerve/anatomy & histologyABSTRACT
In this cadaveric study, we analysed digital images of dissected palms to define the location and length of superficial connections between the median and the ulnar nerves (Berrettini communicating branches). We found the connections present in 12 of 27 hands. We used a coordinate model to define their location relative to seven specified landmarks. The model revealed that the Berrettini communicating branches were positioned consistently, and we defined a high-risk zone in the palm that fully contained seven of the 12 connections, while others had minor projections outside the zone. We conclude that awareness of this high-risk zone in the palm can be of some help to reduce the risk of iatrogenic nerve injury, however, any operation in the palm must always be done with great care to visualize and protect any possible anatomically unusual structures.
Subject(s)
Median Nerve , Ulnar Nerve , Cadaver , Hand/innervation , Hand/surgery , Humans , Median Nerve/surgery , Ulnar Nerve/anatomy & histologyABSTRACT
Light touch reduces sway during standing. Unexpected displacement of a light touch reference at the finger can produce rapid responses in ankle muscles when standing, suggesting cutaneous receptors in the hand are functionally coupled with ankle muscles. Using microneurography in the median nerve, we tested the hypotheses: 1) that cutaneous afferent activity of mechanoreceptors of the hand would modulate electromyographic (EMG) activity of ankle muscles, and 2) that displacement of a light touch contact across a receptor's sensory territory would be encoded in the afferent activity. Spike-triggered averaging of EMG activity of tibialis anterior (TA) and soleus (SOL) demonstrated that 34 of 42 (81%) cutaneous afferents recorded modulated activity of ankle muscles with latencies between 40 and 119 ms. Cutaneous afferents of all types (slow and fast adapting, types I and II) demonstrated responses in TA and SOL, in both the ipsilateral and contralateral leg. Activity from 11 cutaneous afferents was recorded while a light touch contact was displaced across their receptive fields. Afferent activity increased with stimulus onset and remained elevated for the stimulus duration for all afferents recorded. These results suggest that cutaneous afferents from the hand consistently form connections with motor pools of the leg at latencies implicating spinal pathways. In addition, the same population of afferents is readily excited by the displacement of a light touch contact. Therefore, cutaneous receptors of the hand can be recruited and used to alter motoneuron pool excitability in muscles important to balance control, at latencies relevant for rapid balance responses.NEW & NOTEWORTHY Light touch provides cutaneous feedback argued to contribute to balance control and shown to reduce postural sway. We demonstrate that activity of cutaneous afferents in the median nerve modulates motor pool excitability of ankle muscles at short latencies and that these afferents respond when a light touch contact is displaced. These findings suggest that cutaneous receptors of the hand can contribute to rapid regulation of muscle activity important to standing balance.
Subject(s)
Ankle , Hand , Ankle Joint , Electromyography , Hand/innervation , Muscle, Skeletal/physiologyABSTRACT
Isolated compression of the recurrent motor branch of the median nerve is an uncommon condition encontered in the daily life of the hand surgeon. Its early identification and correction can optimize functional outcomes. Among the few causes described, there are only 2 case reports of compression by fascial bands. We present a case of isolated compression of the recurrent motor branch of the median nerve secondary to anomalous fascial bands in a 34-year-old male patient, with significant atrophy of the thenar musculature of the right hand. Electroneuromyography showed isolated involvement of abductor pollicis brevis, with no sensory changes. The patient underwent exploration and decompression, recovering opposition and thumb function in 6 months.