Wrist extensor pathomechanics: implications for tendon and nerve transfer.

Central and peripheral nervous system lesions may disrupt the intricate balance of the prime movers of the wrist. In spasticity, hyperactive wrist flexors create a flexion moment and, if untreated, can lead to flexion contractures. In patients with C6 spinal cord injury and tetraplegia, the posterior interosseus nerve is typically affected by a complex pattern of upper and/or lower motoneuron lesions causing radial deviation of the wrist due to loss of ulnar deviation actuators. In this report, we illustrate severe pathomechanics that may occur even with relatively modest changes in wrist balance. These results illustrate how thorough understanding of muscle-tendon-joint interaction aids in designing tendon and nerve reconstructive surgeries to normalize wrist positions and balance in neuromuscular conditions.

Different Thumb Positions in the Tetraplegic Hand.

OBJECTIVE: To analyze factors associated with malposition that affects function of the thumb in individuals with tetraplegia. DESIGN: Retrospective cross-sectional study. SETTING: Rehabilitation Center for Spinal Cord Injury. PARTICIPANTS: Anonymized data from 82 individuals (68 men), mean age 52.9±20.2 (SD) with acute/subacute cervical spinal cord injury C2-C8 AIS A-D recorded during 2018-2020. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Motor point (MP) mapping and manual muscle test (MRC) of 3 extrinsic thumb muscles (flexor pollicis longus (FPL), extensor pollicis longus (EPL), and abductor pollicis longus (APL)). RESULTS: 159 hands in 82 patients with tetraplegia C2-C8 AIS A-D were analyzed and assigned to "key pinch" (40.3%), "slack thumb" (26.4%), and "thumb-in-palm" (7.5%) positions. There was a significant (P<.0001) difference between the 3 thumb positions depicted in lower motor neuron (LMN) integrity tested by MP mapping and muscle strength of the 3 muscles examined. All studied muscles showed a significantly different expression of MP and the MRC values (P<.0001) between the "slack thumb" and "key pinch" position. MRC of FPL was significantly greater in the group "thumb-in-palm" compared with "key pinch" position (P<.0001). CONCLUSIONS: Malposition of the thumb due to tetraplegia seems to be related to the integrity of LMN and voluntary muscle activity of the extrinsic thumb muscles. Assessments such as MP mapping and MRC of the 3 thumb muscles enable the identification of potential risk factors for the development of thumb malposition in individuals with tetraplegia.

[Surgical reconstruction of arm and hand functions in tetraplegia : Current concepts]. / Chirurgische Rekonstruktion der Arm- und Handfunktion bei Tetraplegie : Aktuelle Konzepte.

The reconstruction of arm and hand functions is of enormous importance for tetraplegic patients as it enables at least some degree of independence. Depending on the level of the spinal cord injury, certain residual functions are present in the arms which can be used for surgical reconstruction of upper extremity functions. By utilizing tendon and nerve transfers missing functions can at least be partially reconstructed. Tendon transfers are a proven technique with reliable results that can be performed at any time regardless of the type of accident. Due to the frequent presence of lower motor neuron damage, it is essential to consider the optimal time window for nerve transfer interventions. From the multitude of surgical options, an individual reconstruction plan must be created for each patient, which considers multiple factors. The combination of nerve transfers and later completing the functional reconstruction by tendon transfers is the preferred concept of the authors of this article.

Implications of thumb position and trajectory in tetraplegia grip reconstruction - a cohort study.

STUDY DESIGN: This study represents a retrospective observational cohort study. OBJECTIVES: The objective of this study was to investigate the impact of thumb position on postoperative patient-rated and functional outcomes in grip reconstruction surgery. SETTING: All consecutive adult patients with tetraplegia undergoing grip reconstruction surgery at the Swiss Paraplegic Centre between 06/2008 and 11/2020 were assessed for eligibility. METHODS: Standardized photo or film documentation was used for individually recreating and categorizing thumb position and trajectory during key pinch. Outcome measurements included key pinch strength, Canadian Occupational Performance Measure (COPM) and Grasp Release Test (GRT). RESULTS: Fifty-six hands of 44 patients (mean age 42.2 years, range 18-70 years) with a mean follow-up of 14.8 months (range 6 months to 12 years) were included. There was a significant postoperative improvement of key pinch strength, COPM score and GRT. COPM improvement was more pronounced for hands with more palmar abducted trajectories of the thumb. CONCLUSIONS: Regardless of reconstruction type, pinch strength, patient satisfaction and grasp and release abilities improved significantly after surgery. Thumb position and trajectory are strong determining factors for the selected outcome measurements.

A Prediction Model for Various Treatment Pathways of Upper Extremity in Tetraplegia.

Upper extremity function is essential for the autonomy in patients with cervical spinal cord injuries and consequently a focus of the rehabilitation and treatment efforts. Routinely, an individualized treatment plan is proposed to the patient by an interprofessional team. It dichotomizes into a conservative and a surgical treatment pathway. To select an optimal pathway, it is important to define predictors that substantiate the treatment strategy. Apart from standard assessments (Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), the manual muscle test (MRC), and lower motoneuron integrity of key actuators for hand function performed by motor point (MP) mapping might serve as a possible predictor. Type of damage (upper motor neuron (UMN) or lower motor neuron (LMN) lesion) influences hand posture and thus treatment strategy as positioning and splinting of fingers, hands, arms, and surgical reconstructive procedures (muscle-tendon or nerve transfers) in choice and timing of intervention. For this purpose, an analysis of a database comprising 220 patients with cervical spinal cord injury is used. It includes ISNCSCI, MRC, and MP mapping of defined muscles at selected time points after injury. The ordinal regression analysis performed indicates that MP and ASIA impairment scale (AIS) act as predictors of muscle strength acquisition. In accordance with the innervation status defined by MP, electrical stimulation (ES) is executed either via nerve or direct muscle stimulation as a supplementary therapy to the traditional occupational and physiotherapeutic treatment methods. Depending on the objective, ES is applied for motor learning, strengthening, or maintenance of muscle contractile properties. By employing ES, hand and arm function can be predicted by MP and AIS and used as the basis for providing an individualized treatment plan.

Robot-assisted training with functional electrical stimulation enhances lower extremity function after spinal cord injury.

INTRODUCTION: Functional electrical stimulation (FES) synchronized with robot-assisted lower extremity training is used in spinal cord injury (SCI) rehabilitation to promote residual function. METHODS: Data of SCI inpatients who trained lower limb mobilization on a stationary robotic system were retrospectively analyzed. The primary outcome was the improvement of muscle strength from the first through to the last training session during FES-induced as well as voluntarily induced flexion and extension. The secondary outcome was the sum score of voluntary muscle function in the lower limbs before and after the training period. RESULTS: Data from 72 patients with SCI (AIS A-D) were analyzed. For extension, FES-assisted strength increased (p < 0.001) from 25.2 to 44.0 N, voluntary force (p < 0.001) from 24.4 to 39.9 N. For flexion, FES-assisted flexion (p < 0.006) increased from 14.1 to 19.0 N, voluntary flexion (p < 0.005) from 12.6 to 17.1 N. There was a significant correlation between the increase in FES-assisted force and voluntary flexion (r = 0.730, p = 0.001) as well as between the increase in FES-assisted force and voluntary extension (r = 0.881, p < 0.001). The sum score in muscle test increased from 15 to 24 points. CONCLUSION: Robot-assisted training with FES seems to support the regeneration of residual functions after SCI. This is evidenced by an improvement in motor function and strength in the lower limbs.

Biomechanical Modeling of Brachialis-to-Wrist Extensor Muscle Transfer Function for Daily Activities in Tetraplegia.

We recently reported a novel case demonstrating the feasibility of a brachialis (BRA)-to-extensor carpi radialis brevis (ECRB) tendon transfer, but it is not yet known whether this transfer provides robust functional results across activities. The purpose of this study was to use biomechanical modeling to define the functional capacity of the BRA-to-ECRB tendon transfer in terms of enabling the performance of several activities of daily living. Methods: A model of the transferred BRA-ECRB muscle-tendon unit was developed to calculate isometric elbow and wrist joint torque as a function of elbow and wrist angles resulting from different BRA reattachment locations from 50 to 80 mm proximal to the wrist joint crease. Using this model, mathematical optimization predicted the optimal location for BRA reattachment in order to perform each of a number of important upper extremity tasks as well as to calculate a global optimum for performing all of the tasks. Results: Analysis of active joint torque showed that the entire elbow torque-angle curve surface shifted "diagonally" toward elbow flexion and wrist extension as the attachment location approached the wrist joint; peak wrist torque was produced at extended wrist angles. Our model predicted that the optimal attachment location for each different task ranged from 54.3 to 74.6 mm proximal to the wrist joint, which is feasible given the anatomy of the muscle-tendon unit. The attachment location to optimize performing all tasks was calculated as 63.5 mm proximal to the wrist joint. Conclusions: This study clearly demonstrates that the BRA, which is underused as a donor in tetraplegia surgery, is an excellent donor muscle to provide wrist extension. Biomechanical simulation further highlighted the need to consider not only donor-muscle appropriateness but the patient's desired function when planning surgical tendon transfers. Clinical Relevance: Quantitative evaluation of the way that surgery affects daily tasks rather than simply matching muscle properties may be a more appropriate approach for surgeons to use when choosing and tensioning donor muscles.

Teamwork Pays! Ten Tips for a Great Surgeon-Scientist Collaboration.

This review represents our summary of what makes a great collaboration between a surgeon and a scientist. At first, with no perspective, such a collaboration seems easy and natural. But as time goes on, with more perspective, you realize how special it is. Now, in our 60s, with approximately 35 years of collaboration and 75 coauthored papers (most of them in The Journal of Hand Surgery), we are thankful and humbled for this tremendously fruitful and, importantly, enjoyable collaboration. We are not so foolish to think that we made this great collaboration-it was a gift. However, we now recognize many characteristics that make it great and have developed the following 10 tips.

Five-Year Results of a Randomized, Controlled Trial of Collagenase Treatment Compared With Needle Fasciotomy for Dupuytren Contracture.

PURPOSE: Over the past decade, collagenase treatment and needle fasciotomy (NF) have gained widespread popularity in the treatment of Dupuytren contracture. This prospective study was designed to compare the results of these treatments in terms of clinical and patient-reported outcomes. METHODS: A prospective, randomized, controlled trial included patients with a contracture of 20° or more in a single metacarpophalangeal joint. Patients were allocated to treatment with either NF or collagenase Clostridium histolyticum. The primary outcome was a reduction in the metacarpophalangeal joint contracture to less than 5°. Secondary outcomes included recurrence, the presence of Dupuytren cords, and changes in patient-reported outcomes. The participants were examined 5 years after the intervention. RESULTS: The study cohort comprised 156 patients divided into 2 equally sized groups. After 5 years, data were collected from 143 (92 %) of the initially enrolled participants. The mean time for the clinical follow-up was 5.1 years. In the remaining cohort without a second procedure, 51% (23 patients) in the collagenase Clostridium histolyticum group and 47% (27 patients) in the NF group still had extension deficits of less than 5°. Among the participants with a successful initial procedure, the recurrence rate was 56% (36 patients) in the collagenase Clostridium histolyticum group and 45% (30 patients) in the NF group. There were no differences between the 2 treatments in regard to passive joint extension, reduction of contracture, range of motion, or patient-reported outcomes. CONCLUSIONS: The 5-year outcomes for NF are similar to those for collagenase in terms of sustained correction, recurrence, presence of Dupuytren cords, and patient-reported outcomes for the treatment of metacarpophalangeal joint contractures. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic I.

Improving hand function after spinal cord injury.

Nerve transfer surgery has expanded reconstructive options for restoring upper extremity function following spinal cord injury. By adding new motor donors to the pool already available through tendon transfers, the effectiveness of treatment should improve. Planning which procedures and in which order to perform, along with their details must be delineated. To meet these demands, refined diagnostics are needed, along with awareness of the remaining challenges to restore intrinsic muscle function and to address spasticity and its consequences. This article summaries recent advances in surgical reanimation of upper extremity motor control, together with an overview of the development of neuro-prosthetic and neuromodulation techniques to modify recovery or substitute for functional losses after spinal cord injuries.

Increased muscle fiber size and pathology with botulinum toxin treatment of upper extremity muscles in cerebral palsy.

Intramuscular injections of botulinum toxin A (BTX) are regularly used to treat skeletal muscle spasticity and relieve pain during rehabilitation therapy. However, while numerous preclinical studies have shown dramatic atrophic changes in muscle, little is known about the long-term effect of toxin on human skeletal muscle. In this study, muscle morphology was analyzed in biopsies taken from spastic upper extremity muscles of 8 cerebral palsy patients treated with BTX 5 months to 4 years prior sampling and was compared to muscles from 7 patients who had not ever received BTX treatment (overall 25 muscle biopsies obtained from 6 different muscles.). The most important (and surprising) finding was that BTX-treated muscles contained significantly larger fibers compared to untreated muscles. A strong correlation between fiber size and age was observed but the growth rate in the BTX group was larger. Pathological signs such as central nuclei, neonatal myosin heavy chain expression, angular fibers and hybrid fibers (expressing both slow and fast myosin heavy chain fibers) were significantly greater in BTX-treated muscles compared to untreated muscles. Capillarization was also increased in BTX-treated muscle compared to untreated muscles and was the best predictor of fiber size. We suggest that, in the context of spasticity, BTX may block negative, atrophy-inducing pressure of the central nervous system on skeletal muscle or may allow an altered use pattern that should be considered a positive adjuvant to current rehabilitation therapies.

Rebalancing the Spastic Wrist by Transposition of Antagonistic Muscle-Tendon Complex.

Upper limb spasticity and spasticity-induced deformities after upper motor neuron lesions because of traumatic brain injury, encephalitis or cerebral palsy inhibit activities of daily living, result in impaired self-care and often dependence on assistance of carers. A key element of the dysfunction is wrist hyper-flexion and ulnar deviation deformity. Traditionally, this deformity has been corrected by transfer of the spastic flexor carpi ulnaris to the extensor carpi radialis brevis. Instead, this study emphasizes the causative role of the palmar subluxation of extensor carpi ulnaris and describes a surgical correction strategy detailing transfer of extensor carpi ulnaris-to-extensor carpi radialis brevis. This surgery re-establishes and maintains a more favorable muscle-tendon-joint mechanics and hand position. Patient satisfaction is high, time and effort in daily care for patients and caregivers are less, and incidence of complications is low.

Electrical stimulation alters muscle morphological properties in denervated upper limb muscles.

BACKGROUND: Damage to lower motor neuron causes denervation and degeneration of the muscles affected. Experimental and clinical studies of muscle denervation in lower extremities demonstrated that direct electrical stimulation (ES) of muscle can prevent denervation atrophy and restore contractility. The aim of this study was to identify possible myogenic effect of ES on denervated forearm and hand muscles in persons with spinal cord injury (SCI) and tetraplegia. METHODS: This prospective interventional study with repeated measurement design included 22 patients aged 48·6 (± 15·7), 0·25 (0·1/46) years after spinal cord lesion, AIS A-D. In each patient, two electrophysiologically-confirmed denervated muscles in the hand and forearm were analyzed - one extrinsic (Extensor Carpi Ulnaris - ECU) and one intrinsic (1st Dorsal Interosseus - IOD1). Muscles were stimulated for 33 min, five times per week over a 12-weeks period. Using ultrasonography (USG), muscle thickness (MT) and pennation angle (PA) of these muscles were determined at start and end of the stimulation period. FINDINGS: MT of IOD1 increased from 6·3 mm (± 3·2 mm) to 9·2 mm (± 2·4 mm) (p = 0·004) and the PA from 5·5° (± 3·0°) to 11° (± 2·2°) (p = 0·001). The corresponding values for the ECU were 5·5 mm (± 2·5 mm) to 7·0 mm (± 2·2 mm) (p = 0·039) and 5·5° (± 3·4°) to 9·4° (± 3·8°) (p = 0·005), respectively. The correlation of MT between baseline and completion was r = 0·58 (p = 0·037) for the ECU and r = 0·63 (p = 0·008) for the IOD1. INTERPRETATION: 12 weeks of direct muscle stimulation increases the MT and PA of the denervated intrinsic and extrinsic hand muscles studied. FUNDING: Swiss Paraplegic Centre, Switzerland.

Outcome from a brachialis donor for wrist extension in tetraplegia-time to reconsider the International Classification for Surgery of the Hand in Tetraplegia (ICSHT).

INTRODUCTION: Surgical reconstruction after quadriplegia represents a powerful solution to restore lost function by injury. A case is presented in which surgical reconstruction of a patient with a C4 level spinal cord injury is performed using the brachialis (BRA) muscle as the donor. CASE PRESENTATION: The patient previously had no hand function. This transfer, in combination with fusion of the thumb CMC joint and transfer of the flexor pollicis longus (FPL) tendon to the radius, gives the patient full thumb key pinch powered by BRA transferred to the wrist extensors. Theoretical analysis of muscle architectural properties demonstrates that the BRA has sufficient force and excursion to substitute for both the long and short radial wrist extensors. Furthermore, based on the fact that the BRA has almost twice the excursion compared to the extensor carpi radialis longus (ECRL), wrist extension can occur throughout the entire wrist and elbow ranges of motion. Finally, peak tension is lower than the rupture tension previously measured by us using this type of tendon-to-tendon attachment technique, suggesting that the transfer itself is safe and, importantly, can be immediately mobilized for neuromuscular rehabilitation. DISCUSSION: This procedure can thus restore tremendous functional capacity in patients who were previously categorized as group 0 by the International Classification of Hand Surgery in Tetraplegia (ICSHT). We suggest that, based on the BRA being an excellent donor for surgical reconstruction, that the ICHST system be reconsidered.

Long-term effect of task-oriented functional electrical stimulation in chronic Guillain Barré syndrome-a single-subject study.

OBJECTIVE: Functional electrical stimulation (FES) can enhance motor learning of hand fine motor skills in neurological diseases with upper motoneuron lesions. Nevertheless, FES is rarely applied in patients with chronic Guillan-Barré syndrome (GBS) with preserved deep tendon reflexes allowing for stimulation via nerve. This single case report documents the results of an FES-supported, task-oriented grasp training to regain hand closure and pinch grip. STUDY DESIGN: Single-subject repeated measures study. SETTING: International FES Centre®, Swiss Paraplegic Centre Nottwil. METHODS: Three individually defined goals were formulated and scored by using the goal attainment scale. With a focus on these goals, FES was applied bilaterally to improve hand closure and pinch grip. Based on principles of motor learning FES was executed together with task-oriented movements. The hand closure distance (cm) between the tip of the middle finger and the palmar side of the hand was measured and the achievement of personal, predefined goals evaluated. RESULTS: After 16 weeks of daily stimulation, hand closure could be voluntarily performed. Regained opposition of the thumb to the index finger enabled improved individually defined fine motor control. Restored function remained unchanged in the follow-up at 6 months without stimulation. CONCLUSION: Improving fine motor skills in chronic GBS with intact deep tendon reflexes was possible utilizing FES combined with task-oriented grasp training. These improvements were maintained over time indicating the combination was effective in promoting functionally meaningful motor gains.

Surgical intervention for carpal tunnel syndrome in individuals with spinal cord injuries-patient characteristics, diagnostic considerations, and treatment outcomes.

STUDY DESIGN: A retrospective chart audit. OBJECTIVES: To characterize SCI patients with carpal tunnel syndrome (CTS) and evaluate the diagnostic rationale for surgical decision-making. SETTING: Swiss Paraplegic Centre, Nottwil, Switzerland. METHODS: Retrospective investigation of medical history, diagnostics, surgeries, and outcomes of surgical treatments of CTS in patients with para- and tetraplegia. RESULTS: We identified a total of 77 surgeries for CTS in 55 patients: 16 females (25 surgeries) and 39 males (52 surgeries) with spinal cord injury. The majority (47 persons, 68 surgeries) were paraplegic (level of lesion Th2 and below); 8 persons (9 surgeries) were tetraplegic (level of lesion Th1 and above). ASIA scores in the tetraplegic group were A: 0, B: 1, C: 4, D: 3 while complete lesions predominated in the paraplegic group (A: 32, B: 4, C: 5, D: 6). Sixty-six out of 77 patients reported total relief of symptoms. Neither nerve conduction velocity nor motor amplitude correlated well with the severity of CTS. Co-morbidity and specific risk factors were rare. CONCLUSIONS: SCI patients with CTS respond well to surgical decompression of median nerve regardless of level and type of spinal cord lesion and risk factors. Nerve conduction parameters and clinical findings can provide additional diagnostic support of CTS although nocturnal hand paresthesia, wrist pain at and after loading as well as failed conservative treatment are the main indications for surgical interventions. Based on symptomatology, clinical findings, and nerve conduction studies, we propose a decision-making tree for suggesting surgery or not.

Surgical Mobilization of Skeletal Muscles Changes Functional Properties-Implications for Tendon Transfers.

PURPOSE: Tendon transfer surgery restores function by rerouting working muscle-tendon units to replace the function of injured or paralyzed muscles. This procedure requires mobilizing a donor muscle relative to its surrounding myofascial connections, which improves the muscle's new line of action and increases excursion. However, the biomechanical effect of mobilization on a donor muscle's force-generating function has not been previously studied under in vivo conditions. The purpose of this study was to quantify the effect of surgical mobilization on active and passive biomechanical properties of 3 large rabbit hind limb muscles. METHODS: Myofascial connections were mobilized stepwise from the distal end to the proximal end of muscles (0%, 25%, 50%, and 75% of muscle length) and their active and passive length-tension curves were measured after each degree of mobilization. RESULTS: Second toe extensor, a short-fibered muscle, exhibited a 30% decline in peak stress and 70% decline in passive stress, whereas extensor digitorum longus, a short-fibered muscle, and tibialis anterior, a long-fibered muscle, both exhibited similar smaller declines in active (about 18%) and passive stress (about 65%). CONCLUSIONS: The results highlight 3 important points: (1) a trade-off exists between increasing muscle mobility and decreasing force-generating capacity; (2) intermuscular force transmission is important, especially in second toe extensor, because it was able to generate 70% of its premobilization active force although most fibers were freed from their native origin; and (3) muscle architecture is not the major influence on mobilization-induced force impairment. CLINICAL RELEVANCE: These data demonstrate that surgical mobilization itself alters the passive and active force-generating capacity of skeletal muscles. Thus, surgical mobilization should not be viewed simply as a method to redirect the line of action of a donor muscle because this procedure has an impact on the functional properties of the donor muscle itself.

Upper and lower motor neuron lesions in tetraplegia: implications for surgical nerve transfer to restore hand function.

Nerve transfers (neurotizations) performed under optimal conditions can restore some voluntary control in muscles of the upper extremities in patients with tetraplegia. However, the type of motoneuron lesions in target muscles for nerve transfers influences the functional outcome. Using standardized maps of motor point topography, surface electrical stimulation reliably defines the kind and extent of motoneuron lesion in the selected muscles. In a muscle with an intact lower motor motoneuron, nerve transfers can often successfully reinnervate the chosen key muscle. Conversely, in a lower motoneuron lesion, the nerve transfer outcome is less predictable. However, direct muscle stimulation appears to ameliorate the morphological precondition, a finding that necessitates new preoperative approaches to optimize reinnervation in denervated/partially denervated muscles. Therefore, understanding the impact of electrical stimulation in diagnostics, prognostics, and treatments of upper limbs in tetraplegia is critical for neurotization procedures.

Motor Point Topography of Fundamental Grip Actuators in Tetraplegia: Implications in Nerve Transfer Surgery.

The differentiation between an upper motoneuron (UMN) lesion and lower motoneuron (LMN) lesion of forearm muscles in patients with tetraplegia is critical for the choice of treatment strategy. Specifically, the M. pronator teres (PT), M. flexor digitorum profundus III (FDPIII), and M. flexor pollicis longus (FPL) were studied since they represent key targets in nerve transfer surgery to restore grasp function. Forearm muscles of 24 patients with tetraplegia were tested bilaterally with electrical stimulation (ES) to determine whether UMN or LMN lesion was present. For detecting and testing the nerve stimulation points, a standardized mapping was developed and clinically applied. The relationship between the anatomical segmental spinal innervation and the innervation pattern tested by ES was determined. The data of 44 arms were analyzed. For PT, 19 arms showed an intact UMN, 18 arms an UMN lesion, and seven arms partial denervation. For FDPIII, three arms demonstrated an intact UMN, 26 arms an UMN lesion, 10 arms partial denervation, and five arms denervation. For FPL, two arms presented an intact UMN, 16 arms an UMN lesion, 12 arms partial denervation, and 14 arms denervation. A total of 20.1% ES tested muscles were partially denervated. In four patients, only one arm could be tested because of surgery-related limitations. According to the level of lesion and the segmental spinal innervation, most denervated muscles were present in the patient group C6 to C8. The ES, together with the developed mapping system, is reliable and can be recommended for standardized testing in surgery and rehabilitation. It offers the possibility to detect if and to what extent UMN and LMN lesions are present for the target muscles. It allows for refined pre-operative diagnostics and prognostics in spinal cord injury neurotization surgery.

Regional estimates of cortical thickness in brain areas involved in control of surgically restored limb movement in patients with tetraplegia.

Context/Objective: Spinal cord injury (SCI) causes atrophy of brain regions linked to motor function. We aimed to estimate cortical thickness in brain regions that control surgically restored limb movement in individuals with tetraplegia. Design: Cross-sectional study. Setting: Sahlgrenska University hospital, Gothenburg, Sweden. Participants: Six individuals with tetraplegia who had undergone surgical restoration of grip function by surgical transfer of one elbow flexor (brachioradialis), to the paralyzed thumb flexor (flexor pollicis longus). All subjects were males, with a SCI at the C6 or C7 level, and a mean age of 40 years (range = 31-48). The average number of years elapsed since the SCI was 13 (range = 6-26). Outcome measures: We used structural magnetic resonance imaging (MRI) to estimate the thickness of selected motor cortices and compared these measurements to those of six matched control subjects. The pinch grip control area was defined in a previous functional MRI study. Results: Compared to controls, the cortical thickness in the functionally defined pinch grip control area was not significantly reduced (P = 0.591), and thickness showed a non-significant but positive correlation with years since surgery in the individuals with tetraplegia. In contrast, the anatomically defined primary motor cortex as a whole exhibited substantial atrophy (P = 0.013), with a weak negative correlation with years since surgery. Conclusion: Individuals with tetraplegia do not seem to have reduced cortical thickness in brain regions involved in control of surgically restored limb movement. However, the studied sample is very small and further studies with larger samples are required to establish these findings.