Lumbrican

Adhesions between the interosseous and lumbrical muscles involving the deep transverse metacarpal ligament (dTML) can be a cause of chronic pain and reduced range of motion. New reports on this condition are rare. We identified five patients experiencing pain, swelling and decreased range of motion in the metacarpophalangeal (MCP) joints during manual load. The condition was caused by a direct trauma. After not responding to conservative treatment, patients underwent surgery. Time between trauma and surgery was on average 16 months and the mean postoperative follow-up was 8 months. The lumbrical-interosseus junction was exposed by volar or dorsal incision, adhesions were widely released and the distal third of the dTML was resected. This resulted in normal passive excursion of the muscles and the tendon junction. At the mean follow-up time 8.2 months (3-18) after surgery, all patients were pain-free and had gained near normal range of motion in the MCP joints. Interosseous-lumbrical adhesions may be more common than reflected by the literature. Hand surgeons should keep this condition in mind in cases with chronic inter-metacarpal pain after trauma or infection. Surgical exploration is relatively straight forward and tends to lead to gratifying results. Level of Evidence: IV (therapeutic).

Background: Paraesthesia reflects an abnormality affecting the sensory pathways anywhere between the peripheral sensory nervous system and the sensory cortex. As with all neurology, the fundamental diagnostic tool is a concise history, devoid of potentially ambiguous jargon, which properly reflects the true nature of what the patient is experiencing, provocateurs, precipitating and relieving factors, concomitant illnesses, such as diabetes, and any treatments that could evoke neuropathies. Objective: Some localised neuropathies, such as carpal tunnel syndrome (CTS) or ulnar neuropathy, produce classical features, such as weakness of the 'LOAF' (lateral two lumbricals, opponens pollicis, abductor pollicis brevis and flexor pollicis brevis) median innervated muscles, thereby obviating need for further neurophysiology. Nerve conduction studies may be necessary to diagnose peripheral neuropathy, but they may also be normal with small fibre neuropathy. Even with a diagnosis of peripheral neuropathy, definition of the underlying cause may remain elusive in a significant proportion of cases, despite involvement of consultants. Discussion: Treatment is based on the relevant diagnosis and mechanism to address the cause. This includes better glycaemic control for diabetes, night splint for CTS or elbow padding for ulnar neuropathy, modifying lifestyle with reduced alcohol consumption or replacing dietary deficiencies or changing medications where appropriate and practical. Should such intervention fail to relieve symptoms, consideration of intervention to relieve symptoms of neuropathic pain may be required.

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.