First Lumbrical Muscle Flap for Recurrence of Carpal Tunnel Syndrome: Anatomical Study and Surgical Technique

Recurrence of carpal tunnel syndrome implies the reappearance of symptoms after release surgery. If the cause of recurrence is not an incomplete release, but a traction neuritis, the tendency is to add to the revision surgery of the carpal tunnel the use of flaps to cover the median nerve. These flaps establish a physical barrier between the nerve and the rest of the adjacent structures, preventing adhesions, and providing neovascularization and better nerve sliding.In the present work, we detail a revision surgery in which the first lumbrical muscle is used as a covering flap. This flap has two benefits. Firstly, it acts as a vascularized coverage for the median nerve (avoiding the formation of fibrosis and favoring its sliding); secondly, a structure that takes up space is removed from the carpal tunnel, thus reducing the pressure within it.Along with the explanation of the technique, the present article provides a detailed description of the anatomical variability of the first lumbrical muscle and its vascularization, as well as the results of a cadaveric study on the location of the vascular pedicle of the first lumbrical muscle.

Lumbrical Muscles Neural Branching Patterns: A Cadaveric Study With Potential Clinical Implications

Background Lumbrical muscles originate in the palm from the 4 tendons of the flexor digitorum profundus and course distally along the radial side of the corresponding metacarpophalangeal joints, in front of the deep transverse metacarpal ligament. The first and second lumbrical muscles are typically innervated by the median nerve, and third and fourth by the ulnar nerve. A plethora of lumbrical muscle variants has been described, ranging from muscles’ absence to reduction in their number or presence of accessory slips. The current cadaveric study highlights typical and variable neural supply of lumbrical muscles. Materials Eight (3 right and 5 left) fresh frozen cadaveric hands of 3 males and 5 females of unknown age were dissected. From the palmar wrist crease, the median and ulnar nerve followed distally to their terminal branches. The ulnar nerve deep branch was dissected and lumbrical muscle innervation patterns were noted. Results The frequency of typical innervations of lumbrical muscles is confirmed. The second lumbrical nerve had a double composition from both the median and ulnar nerves, in 12.5% of the hands. The thickest branch (1.38 mm) originated from the ulnar nerve and supplied the third lumbrical muscle, and the thinnest one (0.67 mm) from the ulnar nerve and supplied the fourth lumbrical muscle. In 54.5%, lumbrical nerve bifurcation was identified. Conclusion The complex innervation pattern and the peculiar anatomy of branching to different thirds of the muscle bellies are pointed out. These findings are important in dealing with complex and deep injuries in the palmar region, including transmetacarpal amputations.

Caffeine attenuates contraction-induced diminutions of the intracellular calcium transient in mouse lumbrical muscle ex vivo

The amount of calcium released from the sarcoplasmic reticulum in skeletal muscle rapidly declines during repeated twitch contractions. In this study, we test the hypothesis that caffeine can mitigate these contraction-induced declines in calcium release. Lumbrical muscles were isolated from male C57BL/6 mice and loaded with the calcium-sensitive indicator, AM-furaptra. Muscles were then stimulated at 8 Hz for 2.0 s in the presence or absence of 0.5 mM caffeine, at either 30 °C or 37 °C. The amplitude and area of the furaptra-based intracellular calcium transients and force produced during twitch contractions were calculated. For each of these measures, the values for twitch 16 relative to twitch 1 were higher in the presence of caffeine than in the absence of caffeine at both temperatures. We conclude that caffeine can attenuate contraction-induced diminutions of calcium release during repeated twitch contractions, thereby contributing to the inotropic effects of caffeine.

Innervation Patterns of the Lumbrical Muscles of the Foot in Human Fetuses

Background We sought to describe the innervation patterns of the foot lumbrical muscles and their morphological properties in human fetuses and to define the communicating branches between the medial (MPN) and lateral (LPN) plantar nerves, which play a part in the innervation of those muscles. Methods Thirty formalin-fixed fetuses (13 male and 17 female) with a mean ± SD gestational age of 25.5 ± 3.8 weeks (range, 18–36 weeks) from the inventory of the Mersin University Faculty of Medicine Anatomy Department were bilaterally dissected. Innervation patterns of the lumbrical muscles and the communicating branches between the MPN and the LPN were detected and photographed. Results No variations were seen in lumbrical muscle numbers. In the 60 feet, the first lumbrical muscle started directly from the flexor digitorum longus tendon in 48 and from the flexor hallucis longus slips in addition to the flexor digitorum longus tendon in 12. Fifty-five feet had the classic innervation pattern of the lumbrical muscles, and five had variations. No communicating branches were seen in 48 feet, whereas 12 had connections. Conclusions This study classified innervation patterns of the foot lumbrical muscles and defined two new innervation types. During surgeries on the foot and ankle in neonatal and early childhood terms, awareness of the communicating branches between the MPN and the LPN and innervation of the intrinsic muscles of the foot, such as the lumbrical muscles, might aid in preventing possible complications.

Identification of Aberrant Muscle Bellies in the Carpal Tunnel Using Sonography

Musculoskeletal sonography is being widely used for evaluation of structures within the carpal tunnel. While some anatomical variants, such as bifurcated median nerves and persistent median arteries, have been well documented, limited literature describes the sonographic appearance of aberrant muscle bellies within the carpal tunnel. Multiple examples of the sonographic appearance of flexor digitorum superficialis and lumbrical muscle bellies extending into the carpal tunnel are provided. Techniques for static image acquisition and analysis are discussed, and the use of dynamic imaging to confirm which specific muscle belly is involved is described. Knowledge of the potential presence of muscle bellies in these images and ability to identify these structures is vital to avoid misclassification or misdiagnosis as abnormal pathology. The case examples are situated among current published evidence regarding how such anomalies may be related to the development of pathologies, such as carpal tunnel syndrome.

Lumbrical muscle tear: clinical presentation, imaging findings and outcome

The incidence of lumbrical muscle tear is increasing due to the popularity of climbing sport. We reviewed data from 60 consecutive patients with a positive lumbrical stress test, including clinical examination, ultrasound and clinical outcomes in all patients, and magnetic resonance imaging in 12 patients. Fifty-seven patients were climbers. Lumbrical muscle tears were graded according to the severity of clinical and imaging findings as Grade I–III injuries. Eighteen patients had Grade I injuries (microtrauma), 32 had Grade II injuries (muscle fibre disruption) and 10 had Grade III injuries (musculotendinous disruption). The treatment consisted of adapted functional therapy. All patients completely recovered and were able to return to climbing. The healing period in Grade III injuries was significantly longer than in the patients with Grade I or II injuries ( p < 0.001). We recommend evaluation of specific clinical and imaging findings to grade the injuries and to determine suitable therapy. Level of evidence: IV