Hypothenar Research Articles

Muscle echogenicity ratio can indicate severity of carpal tunnel syndrome.

The purpose of this study was to investigate the usefulness of the echogenicity (EI) ratio of the thenar to hypothenar muscle measured using ultrasonography in assessing the severity of carpal tunnel syndrome (CTS). Fifty-nine hands of 30 patients electrodiagnostically confirmed as having CTS were classified into 3 subgroups (mild, moderate, and severe). The EI of the thenar and hypothenar muscles was measured with ultrasonography, and the EI ratio was calculated in the patients and 13 normal participants (26 hands). The average EI ratio was higher in the CTS group than in the control group. We also found a positive correlation between the severity of CTS and a high EI ratio measured with ultrasonography. The EI ratio of the thenar to hypothenar muscle is a useful parameter that can indicate the severity of CTS. Muscle Nerve 58: 304-306, 2018.

4. Median/ulnar nerve ultrasound cross-sectional area ratio in ALS

Background It has been shown that hand muscle wasting in amyotrophic lateral sclerosis (ALS) preferentially affects the thenar muscles, with relative sparing of the hypothenar muscles. This so-called “split-hand” is clinical sign that can be used to differentiate ALS from mimic disorders, and is thought to be caused by a difference in nerve excitability between median and ulnar nerve. The split-hand phenomenon has been largely discussed in regard to neurophysiological finding, but no studies performed comparing median and ulnar nerve size using ultrasound. We therefore sought to compare nerve size between the median and ulnar nerves in ALS using ultrasound in order to determine whether this may give further insight into the split-hand phenomenon. Objective To identify whether nerve ultrasound results might reflect the clinical split-hand sign in ALS patients and whether these findings can be used to differentiate ALS from other neuromuscular disorders. Methods Ultrasound was used to image both the median and ulnar nerves of 98 patients with ALS and 82 patients with other neuromuscular disorders (non-ALS). The nerve cross-sectional area (CSA) was measured at the wrist, the forearm, and the upper arm bilaterally. Nerve CSA values and median/ulnar nerve CSA ratios were compared at different locations between the two groups. Result Both the median and ulnar nerve CSA values were smaller in the ALS group than in the non-ALS group, except for the median nerve at the wrist. The median/ulnar nerve CSA ratio was comparatively decreased in the upper arm segment. There was a significant difference between the two groups at the wrist on the left side and at upper arm on the right side (Left wrist (IQR) ALS: 2.00 (1.67, 2.33) vs non-ALS: 1.63 (1.35, 2.18) p = 0.003, Right upper arm (IQR) ALS: 1.29 (1.12, 1.50) vs non-ALS: 1.37 (1.16, 1.69) p = 0.003). Conclusion We observed that the median/ulnar nerve CSA ratio was decreased in ALS patient at the upper arm segment. Overall, these findings suggest that there is preferential involvement of the median nerve compared to the ulnar nerve in ALS, which is consistent with the clinical findings of the split hand in these patients. This adds further support to the involvement of peripheral mechanisms underlying this phenomenon. Therefore, ultrasound may be a useful non-invasive tool to objectively detecting changes. Further studies assessing cortical contribution to the clinical and ultrasound findings are warranted to elucidate this pathology further.

Ulnar Artery Aneurysm and Repair

This is a case study of a patient who was presented to the emergency room with ischemia of the left third, fourth and fifth fingers and a pulsatile mass in the hypothenar eminence. Non-invasive arterial exam of the upper extremities was performed bilaterally which resulted in normal pressures and normal blood flow velocities. The arterial duplex imaging was also normal in the subclavian, axillary, brachial, radial and ulnar arteries and also demonstrated triphasic Doppler flow velocities. The technologist scanned distal to the wrist where a branch of the ulnar artery along with the aspect of the palmer arch surface revealed a true aneuryms with both antegrade and retrograde flow. The patient was infused tissue plasminogen activator (TPA) for a total of 72 hours with eventual recanalization of the thrombosed aneurysm. Due to the high risk of limb threat the patient underwent a successful resection of the left ulnar artery aneurysm with vein patch.

Ultrasound‐Guided Microinvasive Carpal Tunnel Release Using a Novel Retractable Needle‐Mounted Blade: A Cadaveric Study

Ultrasound (US)-guided microinvasive procedures are defined as those performed via needles without notable scarring. Ten cadaver hands underwent US-guided microinvasive carpal tunnel release using a novel needle-based tool, the micro i-Blade (Summit Medical Products, Inc, Sandy, UT). A US-imaged landmark, the inflexion point of the ligaments distal to the hook of the hamate, was used to position the distal extent of the cut. The transverse carpal ligament was successfully released in all hands without damage to nerves or arteries. In 3 specimens, the fascia between the thenar and hypothenar muscles was partly preserved, whereas the palmar aponeurosis was partly cut in 1 specimen. The micro i-Blade with the cutting knife retracted was also useful as a probe palpated through the palm of the cadaver hand, to test the release of the transverse carpal ligament and to guide the procedure.

In Vivo Electrophysiological Measurement of the Rat Ulnar Nerve with Axonal Excitability Testing.

Electrophysiology enables the objective assessment of peripheral nerve function in vivo. Traditional nerve conduction measures such as amplitude and latency detect chronic axon loss and demyelination, respectively. Axonal excitability techniques "by threshold tracking" expand upon these measures by providing information regarding the activity of ion channels, pumps and exchangers that relate to acute function and may precede degenerative events. As such, the use of axonal excitability in animal models of neurological disorders may provide a useful in vivo measure to assess novel therapeutic interventions. Here we describe an experimental setup for multiple measures of motor axonal excitability techniques in the rat ulnar nerve. The animals are anesthetized with isoflurane and carefully monitored to ensure constant and adequate depth of anesthesia. Body temperature, respiration rate, heart rate and saturation of oxygen in the blood are continuously monitored. Axonal excitability studies are performed using percutaneous stimulation of the ulnar nerve and recording from the hypothenar muscles of the forelimb paw. With correct electrode placement, a clear compound muscle action potential that increases in amplitude with increasing stimulus intensity is recorded. An automated program is then utilized to deliver a series of electrical pulses which generate 5 specific excitability measures in the following sequence: stimulus response behavior, strength duration time constant, threshold electrotonus, current-threshold relationship and the recovery cycle. Data presented here indicate that these measures are repeatable and show similarity between left and right ulnar nerves when assessed on the same day. A limitation of these techniques in this setting is the effect of dose and time under anesthesia. Careful monitoring and recording of these variables should be undertaken for consideration at the time of analysis.

Intramuscular hemangioma of the hypothenar eminence. A case report

Intramuscular hemangiomas are benign vascular tumors. They develop in striated muscles. Various sites have been reported in the literature but only rarely in the hand. We report on a case of an intramuscular hemangioma located within the hypothenar eminence, diagnosed by a biopsy. Treatment options are limited in the hand as embolization may lead to a risk of digital ischemia and sclerotherapy may lead to recurrence. This type of infiltrating tumor is poorly structured within the muscle, thus simple removal is not an option. Surgical excision of the entire affected muscle, in our case the abductor digiti minimi, was performed without any consequences on the hand's function and no signs of recurrence at the latest follow-up of 6months.

ACCP Virtual Poster Symposium

<scp>ACCP</scp> Virtual Poster Symposium

Electrical impedance myography changes after incomplete cervical spinal cord injury: An examination of hand muscles

ObjectiveThis study was to apply the newly developed electrical impedance myography (EIM) technique to examine hand muscles in patients with an incomplete cervical spinal cord injury (SCI). MethodsEIM was performed on the thenar, hypothenar, and first dorsal interosseous (FDI) muscles of SCI (n=16) and age-matched healthy control (n=18) subjects. By sending low intensity and high frequency current through the skin and measuring the consequent voltage, EIM estimates the major impedance parameters, which include resistance (R), reactance (X) and phase angle (θ). ResultsThe SCI group had lower reactance and phase angle (p<0.0001) as compared to the control group in all three muscles, and lower resistance in the thenar muscle (p<0.05). The SCI group also demonstrated a smaller anisotropy in resistance (p<0.0001) and larger anisotropy in phase angle (p<0.05) compared to those from healthy controls. ConclusionThe reduced reactance and phase angle of paralyzed muscles could be due tochanges of membrane integrity and fat infiltration, whereas the change in the anisotropy may reflect the rearrangement of muscle fiber geometry. SignificanceThe EIM provides a quick and convenient tool for examination of muscle alterations after SCI.

Facilitatory and inhibitory pain mechanisms are altered in patients with carpal tunnel syndrome.

Preliminary evidence from studies using quantitative sensory testing suggests the presence of central mechanisms in patients with carpal tunnel syndrome (CTS) as apparent by widespread hyperalgesia. Hallmarks of central mechanisms after nerve injuries include nociceptive facilitation and reduced endogenous pain inhibition. Methods to study nociceptive facilitation in CTS so far have been limited to quantitative sensory testing and the integrity of endogenous inhibition remains unexamined. The aim of this study was therefore to investigate changes in facilitatory and inhibitory processing in patients with CTS by studying hypersensitivity following experimentally induced pain (facilitatory mechanisms) and the efficacy of conditioned pain modulation (CPM, inhibitory mechanisms). Twenty-five patients with mild to moderate CTS and 25 age and sex matched control participants without CTS were recruited. Increased pain facilitation was evaluated via injection of hypertonic saline into the upper trapezius. Altered pain inhibition through CPM was investigated through cold water immersion of the foot as the conditioning stimulus and pressure pain threshold over the thenar and hypothenar eminence bilaterally as the test stimulus. The results demonstrated that patients with CTS showed a greater duration (p = 0.047), intensity (p = 0.044) and area (p = 0.012) of pain in response to experimentally induced pain in the upper trapezius and impaired CPM compared to the control participants (p = 0.006). Although typically considered to be driven by peripheral mechanisms, these findings indicate that CTS demonstrates characteristics of altered central processing with increased pain facilitation and reduced endogenous pain inhibition.

P351 The assessment of repeater F-waves in patients with amyotrophic lateral sclerosis

Objectives Repeater F-waves (Freps) were seen in patients with amyotrophic lateral sclerosis (ALS). The factors implicated for the presence and frequency of Freps were loss of the motor neurons and the changes in their excitability. The aim of this study was to assess the Freps in ALS patients and to compare their frequencies in thenar and hypothenar muscles. Methods Sixteen ALS patients and 11 healthy controls were recruited to the study. All patients had ⩾2 mV CMAPs recorded from the hand muscles. Ninety F-waves were recorded from abductor digiti minimi (ADM) and abductor pollicis brevis (APB). The index of repeater neurons (RN) and Freps were calculated. Results Mean index RN and index Freps values of ADM and APB muscles in ALS group (17.1 and 42.6 for ADM and 16.3 and 41.9 for APB) were significantly higher than those of healthy controls (4.7 and 13.9 for APB and 1.5 and 3.6 for ADM). ALS group had a lower persistence of F-waves for both muscles than healthy controls (56.4 and 94.6 for APB and 83.4 and 97.0 for ADM). Freps parameters were not different between thenar and hypothenar muscles, whereas persistence of F-waves was lower in the thenar (56.4%) as compared to the hypothenar (83.4%) muscles. Discussion Similar Freps parameters in the thenar and hypothenar muscles might be caused by the inclusion criteria. Lower F-persistence in the thenar muscles was in accordance with the split-hand phenomenon. Conclusion The assessment of Freps and F persistence may be useful in understanding of the electrophysiological changes in ALS.

P354 The triple stimulation technique and transcranial magnetic stimulation in amyotrophic lateral sclerosis: A prospective study

Objective The aim of the study is to evaluate the diagnostic value of triple stimulation technique (TST) and cortical excitability studies as markers of upper motor neuron degeneration in ALS patients and to compare the extent of electrophysiological changes in abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles. Methods Fifteen patients with ALS and 15 healthy controls (HCs) were included in the study. Motor evoked potential (MEP) responses, contralateral and ipsilateral silent periods (ISP) and paired-stimulation tests were recorded from both hypothenar and thenar muscles simultaneously. Paired-stimulation studies were performed with interstimulus intervals (ISI) of 2 and 3 ms for short-interval intracortical inhibition (SICI) and 10 and 12 ms for intracortical facilitation. TST responses were recorded from APB and ADM muscles. Results ISP duration was significantly shorter in the ALS group both for ADM and APB muscles (31.1 and 27.6 ms in ALS; 43.3, 39.3 ms in HCs respectively). SICI with 2 ms was reduced from thenar and hypothenar muscles in ALS patients when compared with HCs. MEP amplitudes were lower in ALS patients. TST test/control values in ADM and APB muscles were lower in ALS patients (86.4 and 73.7 in ALS; 100.8 and 107.8 in HCs respectively). Although TSTtest/control values had a tendency to be higher in the ADM, the results of the TMS studies were not significantly different between ADM and APB muscles in ALS patients. Conclusion These findings may be indicators of increased cortical excitability together with the upper motor neuron degeneration in ALS patients.

O210 Abnormal movements mimicking tremor in amyotrophic hands in adults

Adult patients presenting with slowly progressive hand weakness and wasting (HWW) without signs of upper motor neuron involvement and unconvincing cervical MRI signs of disk protrusion are a diagnostic challenge. Clinical and electrophysiological follow-up is needed to reach the most probable diagnosis. Objective We describe 4 adult patients who presented with HWW and involuntary tremor-like movements of the thumb. Methods We performed electrodiagnostic testing (EDX) two times, between 3 and 6 months and 12 and 24 months, after onset of symptoms. Cranial and cervical magnetic ressonance and laboratory workout were performed in all patients. Results Hyposthesia in the ulnar territory was the most common complaint that did not change between consultations. Muscle strength was decreased in fingers abduction-adduction movements. Thumb tremor was present and correlated with fasciculations in thenar and interossei muscles. The compound muscle and sensory nerve action potentials were reduced in median and ulnar nerves. We observed denervation signs in thenar and hypothenar muscles but not in biceps. The EDX signs did not change in the second examination. Conclusion Fasciculations in wasted hand muscles may induce involuntary movements mimicking tremor. Stabilization of symptoms and neurophysiological data favor spinal cord focal lesions over motor neuron disease.

MRI of the Intrinsic Muscles of the Hand.

AbstractThis review article reviews muscle function and anatomy, describes normal magnetic resonance (MR) imaging anatomy, and shows a spectrum of abnormal imaging findings. It covers the lumbrical, interosseous, and thenar and hypothenar muscles. The described spectrum of abnormalities includes anatomical variants, exercise-induced MR signal changes, denervation syndromes, and myositis, as well as tumors. Advanced imaging techniques are discussed at the end to provide a look at future hand muscle imaging.

Reliability of sonographic muscle thickness measurements of the thenar and hypothenar muscles.

The thickness of the thenar and hypothenar muscles of both hands of 15 volunteers (7 male, 8 female) were evaluated with a 4-13-MHz linear probe by 2 examiners who were blinded to each other's measurements. Interrater reliability was then evaluated. To assess intrarater reliability, the first examiner also performed a second measurement after an interval of at least 1 day. Mean age of the subjects was 31.1 ± 9.0 years. Test-retest reliability showed excellent intrarater reliability (intraclass correlation coefficient range: 0.889-0.963) and substantial to excellent results for interrater reliability (intraclass correlation coefficient range: 0.692-0.937). We found that ultrasound is a reliable method for thickness measurements of the thenar and hypothenar muscles. Muscle Nerve 57: E14-E17, 2018.

Fiber type composition of the palmaris brevis muscle: implications for palmar function.

The palmaris brevis (PB) is a small muscle of variant morphology located on the ulnar aspect of the palm, superficial to the hypothenar eminence. Functionally, the PB has been proposed to protect the neurovasculature of the ulnar canal from compressive forces during repetitive or intermittent trauma associated with grasping. Although PB function has been inferred from cadaveric observations, it is unknown whether it has the contractile capacity and fatigue-resistance necessary to withstand these functional demands. Insight into the functional specialization of the PB can be provided through investigating the proportions of type I and type II muscle fibers by staining for myosin heavy chain (MHC) isoforms using immunohistochemical methods. Therefore, the purpose of this study was to quantify the proportion of type I and type II muscle fibers to provide insight into the role of the PB in palmar function based on its gross histological structure. Sixteen PB specimens were harvested from the hands (eight right, eight left) of eight formalin-embalmed cadavers (mean age: 75±14years; three males, five females). PB muscle composition was determined by labeling serial cross-sections with MHC type I and type II monoclonal antibodies. The results indicate that the PB is primarily composed of type I muscle fibers (72.2±13.7%), with no significant differences between left and right hands. Given the predominance of type I muscle fibers, our findings indicate the PB may be fatigue-resistant and thus, capable of contracting for prolonged durations. This supports cadaveric observations indicating that the PB functions to protect the ulnar neurovasculature of the palm by providing a muscular barrier in addition to serving as a functional anchor to the hypothenar fat pad when objects are firmly compressed into the palm.

Sexual Dimorphism in Bones of the Thenar and Hypothenar Aspects of the Hand

Osteoarthritis of the pollical carpometacarpal joint is significantly more prevalent in females than in males. Although a number of hypotheses to explain sex differences in the prevalence of thumb osteoarthritis have been proposed, one possibility is that it is a product of sexual dimorphism where female hands have smaller joint surfaces relative to muscle strength, which results in higher stresses on the joints. Although dimorphism of the skull and long bones has been extensively researched, there are few basic data on female‐versus‐male differences in the short and irregular bones. Therefore, it is unclear whether sexual dimorphism is a relevant avenue of investigation for determining the cause of such sex‐based differences in hand pathology. Because powerful precision gripping is dependent on the thenar and hypothenar muscles, the hand bones with muscle attachments or that are directly subjected to transarticular loading by these muscles are of particular interest. Therefore, we investigated four hand bones contributing to the first and fifth carpometacarpal articulations in a sample of humans of African and European descent, and it was predicted that females would have smaller overall bone volumes and areas, smaller individual joint surface areas, as well as different joint and muscle attachment shapes. The hamate, trapezium, first metacarpal (Mc1), and fifth metacarpal (Mc5) of each individual were laser scanned to generate 3D surface polygon models. Volume and surface area were calculated for each bone as a whole in addition to the areas of specific joint surfaces. The shape of the pollical carpometacarpal joint (proximal Mc1 and distal trapezium) was assessed with quadric fitting functions to determine their dorsovolar and radioulnar curvatures. For the hamate, the orientation of the triquetrohamate joint surface relative to the proximodistal axis was quantified, and for the hamulus (which provides attachments for the flexor digiti minimi brevis, opponens digiti minimi, and flexor carpi ulnaris) its length, width, breadth, and angle were measured. The results indicate that females tend to have bones that are significantly smaller in overall size with correspondingly smaller joint surfaces, and a hamulus that differs in both size and shape. Future work will diversify the sample and incorporate measurements of relative thenar and hypothenar muscle force potential to further evaluate the biomechanical consequences of skeletal dimorphism. Such an approach may allow us to better investigate more specific factors contributing to the increased osteoarthritis risk in the hands of females.Support or Funding InformationNational Science Foundation (BCS‐1539741, BCS‐1317047), Wenner‐Gren Foundation, Leakey Foundation

Chronic inflammatory demyelinating polyneuropathy presenting with autonomic symptoms: a case report

A 31 year old female presented with a one-year history of burning sensations, numbness and tingling feelings in her hands and feet. There was also excessive sweatiness of her hands and feet while experiencing these symptoms. Her symptoms were worse at night and during hot weather conditions and aggravated by contact with light clothing. She could not tolerate her shoes. She also complained of weakness in her distal lower limbs. Examination revealed prominent wasting of the thenar and hypothenar eminences, marked bilateral weakness of hand grip, palmar, and dorsal interossei. There was also the significant weakness of the dorsiflexor of the feet with allodynia. Vibration and joint position sense were impaired in the distal lower limbs. Ankle reflexes were diminished. Nerve conduction studies showed nerve conduction block in three nerves. She also had abnormalities from motor and sensory nerve conduction studies involving multiple nerves. She showed remarkable improvements in her symptoms after a course of pulsed oral dexamethasone therapy.

Candidemia with Prosthetic Aortic Graft: Case Report

Infections of prosthetic aortic grafts status post-acute aortic dissection with Candida albicans (C. albicans) are rare. The gold standard of treatment for aortic graft infection is a combination of surgical resection and lifelong antimicrobial drug therapy, however postoperative mortality rates remain high. Here we present a 44-year-old man who presented with 2 months of fever, painful microembolic lesions localized to his right hypothenar eminence, right conjunctival hyperemia, right neural hearing loss, and a systolic murmur radiating from the aorta towards the neck. C. albicans was isolated from 3 separate blood cultures. Computed tomography (CT) displayed distinct thrombotic material affixed to the aortic prosthetic graft in the brachiocephalic artery. The patient was then treated with intravenous (IV) fluconazole for 8 weeks. During the treatment period, the patient suffered from brain hemorrhage in the right temporal lobe, presenting with hemiparalysis. After 8 weeks on IV fluconazole, oral fluconazole was then administered. Through 12 months of follow up, he remained asymptomatic, lab values only notable for slightly elevated inflammatory markers. This case suggests that for some patients, either unwilling or unable to endure surgery, candidemia associated with a prosthetic graft can be managed conservatively, with antifungal therapy alone.

Comparison of Hand Activation using Mirror Therapy on Power Grip

Objectives: This study is aimed to look into what effect mirror therapy has on the muscle activity of a hand when it is applied to healthy individuals. Methods/Statistical Analysis: The participants of the experiment were 22 healthy adults without musculoskeletal disease at upper extremity. For the mirror therapy, a mirror is placed on the center of a table in front of a subject. To check the changing muscle activation between pre-test and post-test the mirror therapy, this study was usedsEMG about MP 36 USA Biopac System. Findings: As a first result about comparison of resting and left movement, the muscle activity was shown to have increased in a thenar muscle, a hypothenar muscle, a flexor bundle muscle, an extensor bundle muscle with a significant statistical difference. As a second result about comparison of right movement and both movement, the muscle activity did not show a significant statistical difference in the thenar muscle, hypothenar muscle, flexor bundle muscle, extensor bundle muscle. Improvements/Applications: Mirror therapy will benefit the muscle activities of patients whose limbs are paralyzed through the brain activation even though there isn’t any movement in the limbs in the future.

The pisotriquetral joint: osteoarthritis and enthesopathy.

Pisotriquetral (PT) osteoarthritis (OA) and enthesopathy of the flexor carpi ulnaris (FCU) are pathologies of the hypothenar eminence which both often remain undiagnosed, but can cause ulnar wrist pain. This study determined the prevalence of these pathologies in an older donor population. Twenty wrists were obtained from 10 cadavers with an age ranging from 65 to 94years. Radiographs were taken of all wrists with the hand in pisotriquetral view and were assessed for osteoarthritic changes of the PT joint and signs of enthesopathy of the FCU. Ten wrists were grossly dissected and the other ten wrists were sagitally sectioned at a thickness of 10μm. The wrists were analyzed for type and grade of osteoarthritis and signs of enthesopathy. On radiology, 2 out of 20 wrists showed no signs of osteoarthritis, 5 wrists showed severe changes. One wrist showed signs of enthesopathy. On macroscopy, 9 out of 10 wrists showed osteoartritic changes; 5 of these were severely osteoarthritic. On microscopy, all wrists showed some degree of osteoarthritis of which five showed severe changes. Signs of enthesopathy were seen in seven wrists. Pisotriquetral osteoarthritis has a high prevalence in the older donor population and may therefore be a cause of ulnar sided wrist pain. It should therefore always be considered in the differential diagnosis of ulnar sided wrist pain. By performing clinical examination with these pathologies in mind, diagnosis could be a lot faster. Furthermore, based on our results, radiographs seem to be not accurate in diagnosing osteoarthritis of the PT joint and enthesopathy of the FCU.