Thenar Group Research Articles

(320) COMPARISON OF TENACIO™ PUMP AND MS™ PUMP EFFICIENCY USING SURFACE ELECTROMYOGRAPHY (SEMG)

Abstract Introduction Inflatable penile implant (IPP) pumps can be difficult to inflate, especially in older men. Efforts to increase the ease of use for IPP pumps should allow for more men to benefit from IPPs. Objective This study compares the muscular effort required to use the TENACIO and MS pumps in an ex-vivo bench top trial. Methods Two pumps (Boston Scientific’s MS™ and TENACIO™ Pumps) were utilized in an ex-vivo, head-to-head trial. Four separate tasks were performed on identical AMS 700™ IPP with: 1] Fill from empty to max (3 consecutive pumps where pump is not fully compressed), 2] Fill from 10 ml to 40 ml, and 3] 10 full pump squeezes (allowing for complete refill of pump between pumps). sEMG (Delsys Trigno®) data was collected from the thenar, flexor digitorum superficialis (FDS), and extensor digitorum (ED) muscles. The sEMG was normalized to the max voluntary contraction (MVC) (Fig. 1). Cumulative muscular workload (CMW) was calculated as time integral of the MVC. Average muscular work per second (AWS) was calculated by dividing CMV by time to completion. Pumps and IPPs were supplied by Boston Scientific. Results A total of 18 trials were performed by 7 participants (1 attending, 4 residents, 2 medical students). Time to completion of each task was significantly faster in the TENACIO group (Fig. 2) compared to the MS group with 30% faster maximal filling (Task 1) for the TENACIO group. There was no difference in CMW between the two pumps for any task across all muscle groups. However, the AWS for TENACIO was significantly higher for all three tasks across all three muscle groups (Table 1). The TENACIO pump was up to 31% more efficient in the thenar group for Task 1, compared to the standard MS device. Conclusions The TENACIO pump is significantly faster at filling and pumps more efficiently compared to the MS pump in an ex-vivo, head-to-head trial utilizing sEMG data. Future studies are needed to understand efficacy in-vivo and patient satisfaction with this pump. Disclosure Yes, this is sponsored by industry/sponsor: Boston Scientific. Clarification: Industry funding only - investigator initiated and executed study. Any of the authors act as a consultant, employee or shareholder of an industry for: Boston Scientific.

Donor-Site Morbidity Analysis of Thenar and Hypothenar Flap.

Background For the small glabrous skin defect, Thenar and Hypothenar skin are useful donors and they have been used as a free flap. Because of similar skin characteristics, both flaps have same indications. We will conduct comparative study for the donor morbidity of the Free thenar flap and Hypothenar free flap. Methods From January 2011 to December 2021, demographic data, characteristics of each flap, and complications using retrospective chart review were obtained. Donor outcomes of the patient, who had been followed up for more than 6 months, were measured using photographic analysis and physical examination. General pain was assessed by Numeric Rating Scale (NRS) score, neuropathic pain was assessed by Douleur Neuropathique 4 Questions (DN4) score, scar appearance was assessed by modified Vancouver Scar Scale (mVSS), and patient satisfaction was assessed on a 3-point scale. Statistical analysis was performed on the outcomes. Results Out of the 39 survey respondents, 17 patients received Free thenar flaps, and 22 patients received Hypothenar free flaps. Thenar group had higher NRS, DN4, and mVSS ( p < 0.05). The average scores for the Thenar and Hypothenar groups were 1.35 and 0.27 for NRS, 2.41 and 0.55 for DN4, and 3.12 and 1.59 for mVSS, respectively. Despite the Hypothenar group showing greater satisfaction on the 3-point scale (1.82) compared with the Thenar group (1.47), the difference was not significant ( p = 0.085). Linear regression analysis indicated that flap width did not have a notable impact on the outcome measures, and multiple linear regression analysis revealed no significant interaction between flap width and each of the outcome measures. Conclusion Despite the limited number of participants, higher donor morbidity in general pain, neuropathic pain, and scar formation was noted in the Thenar free flap compared with the Hypothenar free flap. However, no difference in overall patient satisfaction was found between the two groups.

A Comparative Study of Cross Finger Flap with Thenar Flap for Finger Tip Reconstruction

Introduction: Fingertip injuries are common hand injuries ranging from simple laceration to larger defects with amputations. Different methods are used to reconstruct the affected finger. Cross finger flaps and thenar flaps are commonly used but it is difficult to select among these two flaps to reconstruct the finger in our settings.&#x0D; Method: This is a time-bound prospective comparative study conducted in 14 months duration. The aesthetic (sensibility, appearance and function as subjective assessment) and functional outcomes (2 point discrimination and range of motion) were measured. Data were analyzed using SPSS version 21. Overall significance level was maintained at ‘p’ value &lt; 0.05.&#x0D; Results: There was female predisposition with average age of 34.66 years. The common mode of injury was crush injury with right hand most commonly involved hand and middle finger being commonly injured digit. On subjective assessment, the difference on rating scale on sensibility, function and appearance was not statistically significant among two groups. There were statistical significant differences in mean of static and moving 2 point discrimination among thenar flap and cross finger flap. . The mean active range of motion at three types of joint (MP, PIP, DIP) of finger were 97.660, 82.660 and 38.660 in thenar group and 88.330, 78.660 and 33.660 in cross finger group respectively which were not statistically significant.&#x0D; Conclusion: Our study does not find any precise characteristics for the selection of thenar and cross finger flap based on aesthetic and functional outcomes in reconstruction of fingertip injury.

Myocysticercosis as a rare cause of hand swelling involving thenar group of muscles: A rare case report &amp; literature review

Cysticercosis is a common human parasitic infection caused by larval form of Taemia solium, Cysticercus cellulose. It usually presents as neurocysticercosis. Involvement of skeletal muscles, eyes, subcutaneous tissues, lungs, brain is rare. We report a case of isolated myocysticercosis of thenar group of muscles of hand. Diagnosis of cysticercosis was made on high resolution ultrasound of swelling. Patient was managed conservatively on anthelmintic and anti-inflammatory medications.

A comparative study of two kinds of reverse radial flap for thumb soft tissue reconstruction

Objective To evaluate the clinical results of the thumb dorsoradial flap and the greater thenar flap for coverage of thumb soft tissue defect, and to provide guidance on clinical selection of flaps. Methods From January, 2013 to June, 2014, 23 thumb dorsoradial flaps and 20 greater thenar flaps were used to repair the soft tissues defects in thumbs and were followed up to compare the results. Patient satisfaction, cold intolerance scores, TAM of the reconstructed thumb, sensation (pain and temperature sensation, Semmes-Weinstein monofilament test, static two-point discrimination) and blood perfusion of the flaps were recorded and analyzed statistically. Results Thumb dorsoradial flaps group: patient satisfaction was (36.97 ± 7.70) %, cold intolerance score was 58.96 ± 12.47, TAM of the thumb was (87.57 ± 12.83) °, median Semmes-Weinstein monofilament test was 3.61mm, static two-point discrimination was (14.22 ± 2.84) mm, and blood perfusion was (98.41 ± 15.66) PU. Greater thenar flaps group: patient satisfaction was (50.00 ± 10.80) %, cold intolerance score was 60.45 ± 14.10, TAM of the thumb was (95.00 ± 14.58) °, median Semmes-Weinstein monofilament test was 4.31mm, static two-point discrimination was (20.70 ± 2.56) mm, and blood perfusion was (104.74 ± 14.12) PU. The greater thenar flap had a larger degree of satisfaction than the dorsoradial flap (P 0.05). Conclusion The dorsoradial flap is suitable for repairing the thumb pulp defect due to its good sensation. For the small defect of non-functional dorsal area, the greater thenar flap will be a satisfactory method. Key words: Dorsoradial flap; Greater thenar flap; Island flaps; Thumb; Microsurgical operation

Correction of paralytic hand deformities

The ulnar nerve is most commonly involved in leprosy and is affected at or just above the elbow. The outcome of this damage is paralysis of the intrinsic muscles of the hand with the exception of the thenar group, together with paresis of ring and little finger flexor digitorum profundus (FDP). Although the obvious deformity is clawing of the fingers, other deformities are produced: 1. Hollowing of the intermetacarpal and thumb web space. 2. Flattening of the ulnar half of the hand. 3. Loss of abduction and adduction of the fingers. 4. Instability of metacarpophalangeal joint(MCPJ) 5. Flattening of the distal transverse metacarpal arch. The overall effect is poor grip due unstable MCPJ, poor grasp because of inadequate opening of the hand, rolling of finger tips and a poor pinch due unstable MCPJ of the index finger. Loss of function and anatomical defects needs surgical correction .The appearance of the hand is also very important for leprosy patients, because it is the characteristic deformity which is the principal cause of social rejection. For every single deformity, there is an operative answer. But performing such a large number of operations defeats the very purpose for which these are performed. The goal should be to achieve the best for functional and social needs of the patients with the fewest interventions. The choice for surgery involves a consideration of disease status, condition of the hand, age, extent of paralysis, occupational needs and also the socio-economic background.

Musculoskeletal Disorders of the Upper Extremities Due to Extensive Usage of Hand Held Devices

ObjectiveThe use of hand held devices (HHD) such as mobile phones, game controls, tablets, portable media players and personal digital assistants have increased dramatically in past decade. While sending a text message or using the controls of the HHD the users need to use their thumb and other palm muscles extensively. The objective of this study was to describe the risk factors and clinical features of the musculoskeletal disorders (MSDs) arising due to usage of hand held devices and to evaluate the effectiveness of a sequenced rehabilitation protocol.MethodsA retrospective report analysis of 70 subjects, who were diagnosed to have a MSD affecting the upper extremities, was conducted. Medical charts from a tertiary level rehabilitation centre from 2005–2013 were analysed. All the subjects reported pain in their upper extremities following extensive usage of HHD and were examined and diagnosed to have a MSD by an orthopaedic and rehabilitation physician. After the assessment and diagnosis, all the patients underwent rehabilitation using a sequenced protocol.ResultsAll the subjects reported pain in the thumb and forearm with associated burning, numbness and tingling around the thenar aspect of the hand, and stiffness of wrist and hand. 43 subjects had symptoms on the right side; 9 on left and 18 had bilateral symptoms. Correlation was found between hand dominance and MSD. 33 subjects complained of onset of symptoms following extensive text messaging. All the subjects were diagnosed to have tendinosis of Extensor Pollicis Longus and Myofascial Pain Syndrome affecting the 1st interossei, thenar group of muscles and Extensor Digitorum Communis. 23 of the subjects were senior executives, among these 7 were CEO’s of major multinational companies in India. All the subjects recovered completely following the rehabilitation.ConclusionsThe study concluded that mobile phones and gadgets that promoted the predominant usage of thumb or only one finger while texting or using the controls were associated with a higher prevalence of MSDs. Treatment using a sequenced rehabilitation protocol was found to be effective.

P544: Cortical hyperexcitability of the thenar group of intrinsic hand muscles may contribute to the split-hand sign in ALS

Objective Preferential wasting of the thenar group of intrinsic hand muscles including the abductor pollicis brevis (APB) and first dorsal interosseous (FDI) termed the split-hand sign, has been described as a specific feature of Amyotrophic Lateral Sclerosis (ALS). Greater corticomotorneuronal input to the thenar intrinsic hand muscles has been proposed as one of the pathophysiological mechanisms underlying the split hand sign and consequently difference in cortical excitability between the thenar and hypothenar intrinsic hand muscles was assessed in the present study, in a group of ALS patients and age matched healthy controls. Methods Cortical excitability was recorded using the threshold tracking transcranial magnetic stimulation (TMS) technique from the APB, FDI and abductor digiti minimi (ADM) muscles in 26 Awaji Criteria possible/probable ALS patients (17 male; 9 female; mean age 58.6 ± 1.9 years. Results were compared with 21 age matched healthy controls. Results Short interval intracortical inhibition (SICI) was globally reduced ( P P Conclusion There is a global increase in cortical excitability in ALS, further characterised by a preferential increase in cortical excitability of the APB and FDI muscles, which may underlie the clinical development of the ALS split-hand sign.

1. Cortical hyperexcitability of the thenar group of intrinsic hand muscles may contribute to the split-hand sign in ALS

1. Cortical hyperexcitability of the thenar group of intrinsic hand muscles may contribute to the split-hand sign in ALS

Split-hand plus sign in ALS: Differential involvement of the flexor pollicis longus and intrinsic hand muscles

The flexor pollicis longus (FPL), a key muscle involved in fractionated thumb movements, may be relatively spared in amyotrophic lateral sclerosis (ALS) compared to the thenar group of muscles, termed the split-hand plus sign. Consequently, the diagnostic utility of the split-hand plus sign was prospectively assessed in ALS. In total, 103 patients (37 ALS and 66 non-ALS) with neuromuscular symptoms underwent assessment of FPL and APB strength using the Medical Research Council (MRC) score. A median nerve strength index (MSI) was developed to quantify differential involvement by expressing the APB strength score as a fraction of the FPL strength score. The APB muscle strength was significantly reduced compared to FPL strength in ALS patients (p < 0.0001), but was comparable in the non-ALS disorders (p = 0.91). In addition, there was a significant reduction of MSI scores in ALS patients (MSIALS 0.8; MSInon-ALS 1.0, p < 0.01). Analysis of receiver operating characteristic (ROC) curves disclosed that MSI < 0.9 exhibited an area under the curve of 0.86 (p < 0.001) with a sensitivity of 85% and specificity of 86% for limb-onset ALS. In conclusion, split-hand plus sign distinguished ALS from non-ALS neuromuscular disorders, thereby suggesting a diagnostic utility of this novel clinical sign in ALS.

Split-hand index for the diagnosis of amyotrophic lateral sclerosis

Preferential wasting of the thenar group of muscles, the split hand sign, appears to be a specific feature of ALS. The present study developed a novel split-hand index (SI) and assessed its diagnostic utility in ALS. One hundred and seventy consecutive patients with neuromuscular symptoms (44 ALS, 126 patients with other neuromuscular disorders) were prospectively recruited according to standards for reporting of diagnostic accuracy (STARD) criteria. The SI was derived by dividing the product of the compound muscle action potential (CMAP) amplitude recorded over the first dorsal interosseous and abductor pollicis brevis by the CMAP amplitude recorded over the abductor digiti minimi. The SI was significantly reduced in ALS patients (ALS 3.5 ± 0.6; patients with other neuromuscular disorders 9.1 ± 0.3, P < 0.0001), particularly in limb-onset ALS (2.3 ± 0.5, P < 0.0001). Receiver operating characteristic curve analysis indicated that SI reliably differentiated ALS from patients with other neuromuscular disorders (area under curve ALS 0.83, P < 0.0001) with an optimal SI cut-off value of 5.2 exhibiting a sensitivity of 74% and specificity 80%. The split-hand index robustly differentiates ALS from mimic disorders. The split-hand index is a simple measure that could be utilized in a standard neurophysiology setting. A reduction in SI distinguishes ALS from mimic disorders, potentially facilitating an earlier diagnosis of ALS.

Muscle dimensions in the Japanese macaque hand

Macaques have been used as an important paradigm for understanding the neural control mechanisms of human precision grip capabilities. Therefore, we dissected the forearms and hands of two male Japanese macaques to systematically record the muscle mass, fascicle length and physiological cross-sectional area (PCSA). Comparisons of the mass fractions and PCSA fractions of the hand musculature among the Japanese macaque, chimpanzee, and human demonstrated that the sizes of the thenar and hypothenar eminence muscle groups are more balanced in the macaque and chimpanzee, but those of the thenar eminence group are much larger in the human, indicating that the capacity to generate force at the tip of the thumb is more restricted in macaques, despite their high manual dexterity. In the macaque, however, the extrinsic flexor muscles are much larger, possibly to facilitate weight bearing by the forelimbs in pronograde quadrupedal locomotion and forceful grasping of arboreal supports in gap-crossing movements such as leaping. Taking such anatomical differences imposed on the hand musculoskeletal system into consideration seems to be an important method of clarifying the mechanisms of precision grip in macaques.

Handgrip Maximal Voluntary Isometric Contraction Does Not Correlate with Thenar Motor Unit Number Estimation

In slowly progressive conditions, such as motor neurone disease (MND), 50–80% of motor units may be lost before weakness becomes clinically apparent. Despite this, maximal voluntary isometric contraction (MVIC) has been reported as a clinically useful, reliable, and reproducible measure for monitoring disease progression in MND. We performed a study on a group of asymptomatic subjects that showed a lack of correlation between isometric grip strength and thenar MUNE. Motor unit number estimation (MUNE) estimates the number of functioning lower motor neurones innervating a muscle or a group of muscles. We used the statistical electrophysiological technique of MUNE to estimate the number of motor units in thenar group of muscles in 69 subjects: 19 asymptomatic Cu, Zn superoxide dismutase 1 (SOD 1) mutation carriers, 34 family controls, and 16 population controls. The Jamar hand dynamometer was used to measure isometric grip strength. This study suggests that MUNE is more sensitive for monitoring disease progression than maximal voluntary isometric contraction (MVIC), as MUNE correlates with the number of functional motor neurones. This supports the observation that patients with substantial chronic denervation can maintain normal muscle twitch tension until 50–80% of motor units are lost and weakness is detectable.

Appearance, Phenomenology and Diagnostic Utility of the Split Hand in Amyotrophic Lateral Sclerosis

SUMMARY The split hand has been increasingly recognized as a clinical feature of amyotrophic lateral sclerosis (ALS), heralded by preferential wasting of the thenar group of muscles and the first dorsal interosseous. Although the mechanisms underlying the development of the split hand in ALS remain to be fully elucidated, a cortical basis has been suggested, thereby supporting the notion of upper motor neuron primacy in ALS pathophysiology. In addition, quantifying the split-hand phenomena through the recent development of a novel split-hand index, appears to robustly differentiate ALS from mimic disorders. Taken together, the split-hand index appears to be a useful neurophysiological parameter that has the potential to aid the diagnostic pathway in ALS. The current review discusses the pathophysiological, diagnostic and prognostic utility of the split-hand index in ALS.

Effect of maximal voluntary contraction on the amplitude of the compound muscle action potential: Implications for the interpolated twitch technique

The compound muscle action potential (M(MAX)) during a maximal voluntary contraction (MVC) may be measured to determine if the motor nerve has been supramaximally stimulated during the interpolated twitch technique (ITT). Ten males performed isometric knee extension MVCs. M(MAX) for the vastus medialis was recorded during MVC and rest. To examine the effect of stimulating electrode movement, the M(MAX) of the thenar group and antidromic sensory nerve action potentials (SNAPs) to the third digit were recorded in a separate experiment. M(MAX) during MVC was reduced by 18% (P < 0.0001) and 43% (p < 0.0001) for the quadriceps and thenar group, respectively. The SNAP amplitude was not different between rest and MVC (P = 0.18). Reduction of M(MAX) during MVC suggests that some motor axons are refractory and unable to respond to a superimposed maximal stimulus. These results have implications for the sensitivity of the interpolated twitch technique.

Intramuscular lipoma in thenar or hypothenar muscles.

We report on six patients of intramuscular lipoma of the hand. Four of them occurred in the thenar muscles and two in the hypothenar muscles. The mean age was 49 years (7-68 years). The duration of the lesions prior to excision was averaged as 35 months (12-60 months). Preoperative MRI was taken in all patients, and it was very useful for the diagnosis and differentiation between four well-circumscribed types and two infiltrative types. All operations were performed under loupe magnification. Preoperatively four patients with thenar lipoma had difficulty in moving their thumbs. Two out of four patients with lipomas in the thenar muscles had preoperative intermittent paresthesia and hyperesthesia caused by compression of the radial digital nerve of the thumb. Two patients with lipoma in the hypothenar eminence complained of difficulty with strong grip. The average diameter of the thenar group in its longest dimension was 5.2 cm (3-7 cm), and those of the hypothenar group was 5.5 cm (4-7 cm). At a mean follow-up of 55 months (21-91 months), no tumour had recurred.

Comparative Morphology of Skeletal Muscles in Man and Macaque

The size of skeletal muscle fibre are differentiated into thicker, and thinner fibres by the muscle functions, the former producing more force, the latter fine movements. Histochemically, fibres can also be divided in the thicker, white, last-twitch variants and the thinner, red, slow-twitch fibres. The present study investigates the fibre distribution in several muscles of humans, macaques, and (partly) chimpanzees. In the mono-articular muscles of the thigh, in the m. triceps surae, and in the m. tibialis anterior, the macaques have thinner and less numerous fibres than humans. The intrinsic foot muscles of macaques contain fewer fibres than those of man, and the thenar group as well as the interossei are stronger developed than in humans. The latter possess relatively heavy flexors and extensors of the elbow joint; in macaques (and more so in chimpanzees) the forearm muscles are strongly developed. The laryngeal muscles in humans contain a higher percentage of red fibres than those in macaques, which have more white fibres, while all are thinner than in humans. The outstanding trait in humans is the low number of laryngeal muscle fibres which are innervated by a single nerve fibre. The differences found can be related to the diverging locomotor and vocal hehavior of the respective forms.

Motor unit numbers and contractile properties after spinal cord injury

The number of motor units in the thenar muscle group was estimated in 11 patients with cervical spinal cord injuries. The surface electromyogram and twitch force, in response to maximal stimulation of the median nerve was divided by the average surface electromyogram and twitch of single units. The average single unit size was obtained by intramuscular microstimulation of motor nerve branches and by graded whole nerve stimulation, which provided three independent estimates, two based on the electromyogram and one based on force. The motor unit estimates from the patients covered a wide range. Some had essentially normal motor units both in numbers and contractile properties, while others had varying reductions in numbers of units. Those patients who showed a large reduction in motor unit numbers also had greatly enlarged units, which produced an average of up to sixfold the normal force. These enlarged units summed to produce maximal compound action potentials and twitches that were sometimes indistinguishable from normal. Magnetic resonance imaging scans of the cervical spine obtained from some patients provided independent evidence that patients with low motor unit counts had sustained direct injury to the anterior aspect of the spinal cord at the relevant segmental levels. Some patients showed a normal number of motor units long after the injury. No evidence of transneuronal degeneration could be demonstrated in the thenar group in these patients with the current techniques.

Methods for estimating the number of motor units in human muscles

The number of motor units in the thenar muscle group was calculated by dividing the surface electromyogram and twitch force, in maximal stimulation of the median nerve, by estimates of the average electromyogram and twitch force from single units. The following three techniques were used to estimate the average electromyogram from single units: spike-triggered averaging from units recorded with a needle electrode, intramuscular microstimulation of motor nerve branches, and graded whole nerve stimulation at the wrist. The first two techniques also provided independent estimates of motor unit numbers based on the average force generated by single units. The five estimates (three based on the electromyogram and two on force) ranged from 116 to 170 motor units in the thenar group. Correcting for cancellation when unit responses sum to form the compound action potential or twitch increased the estimated number of units, which ranged from 130 to 179. The estimates were not statistically different from one another but were substantially lower than some previous electrophysiological estimates based on graded whole nerve stimulation. The recruitment pattern of single units during whole nerve stimulation was recorded and simulated mathematically. The most likely reason for the higher estimates in previous studies using graded whole nerve stimulation is shown to be alternation of motor units. Potential errors in all the techniques are discussed and compared.

OPPONENSPLASTY USING THE EXTENSOR DIGITI MINIMI

It is conceded that a solitary tendon transfer cannot be expected to completely restore all aspects of the complex, integrated function of opposition; however, a review of the results obtained in this small series of patients suggests that this procedure can reliably restore useful opposition to the thumb. This operation has certain advantages over the standard procedures which utilize the superficial finger flexors or wrist flexors as motors: 1. The construction of the pulley mechanism is unnecessary; 2. The length of the tendon to be transferred is adequate and there is no need for addition of a tendon graft; 3. There is no need to violate the delicate flexor mechanism as when the flexor superficialis is used as a motor, a procedure not without hazard. 5,15 Success using this transfer in this small series of patients has prompted its use even in patients with available superficial flexor motors. Two additional patients, both with absent thenar group muscles (one secondary to trauma, the other congenital) have undergone this procedure and have achieved good results in the early follow-up period.