Severe Cubital Tunnel Syndrome: Considerations for Nerve Transfer Surgery

Supercharge end-to-side nerve transfer from anterior interosseous nerve to augment intrinsic recovery in high ulnar nerve injuries of varying magnitudes

BACKGROUND

High ulnar nerve injuries result in intrinsic muscle weakness and are inconvenient for patients. Moreover, conventional surgical techniques often fail to achieve satisfactory motor recovery. A potential reconstructive solution in the form of the supercharge end-to-side (SETS) anterior interosseous nerve (AIN) transfer method has emerged. Therefore, this study aims to compare surgical outcomes of patients with transected and in-continuity high ulnar nerve lesions following SETS AIN transfer.

METHODS

Between June 2015 and May 2023, patients with high ulnar palsy in the form of transection injuries or lesion-in-continuity were recruited. The assessment encompassed several objective results, including grip strength, key pinch strength, compound muscle action potential, sensory nerve action potential, and two-point discrimination tests. The muscle power of finger abduction and adduction was also recorded. Additionally, subjective questionnaires were utilized to collect data on patient-reported outcomes. Overall, the patients were followed up for up to 2 years.

RESULTS

Patients with transected high ulnar nerve lesions exhibited worse baseline performance than those with lesion-in-continuity, including motor and sensory functions. However, they experienced greater motor improvement but less sensory recovery, resulting in comparable final motor outcomes in both groups. In contrast, the transection group showed worse sensory outcomes.

CONCLUSIONS

Our findings suggest that SETS AIN transfer benefits patients with high ulnar nerve palsy, regardless of the lesion type. Nonetheless, improvements may be more pronounced in patients with transected lesions.

Ropivacaine microsphere-loaded electroconductive nerve dressings for long-acting analgesia and functional recovery following diabetic peripheral nerve injury

In recent years, electroconductive hydrogels (ECHs) have shown great potential in promoting nerve regeneration and motor function recovery following diabetic peripheral nerve injury (PNI), attributed to their similar electrical and mechanical characteristics to innate nervous tissue. It is well-established that PNI causes motor deficits and pain, especially in diabetics. Current evidence suggests that ropivacaine (ROP) encapsulated in poly lactic-co-glycolic acid (PLGA) microspheres (MSs) yield a sustained analgesic effect. In this study, an ECH electroconductive network loaded with MS/ROP (ECH-MS/ROP) was designed as a promising therapeutic approach for diabetic PNI to exert lasting analgesia and functional recovery. This dual delivery system allowed ROP's slow and sequential release, achieving sustained analgesia as demonstrated by our in vivo experiments. Meanwhile, this system was designed like a lamellar dressing, with desirable adhesive and self-curling properties, convenient for treating injured nerve tissues via automatically wrapping tube-like structures, facilitating the process of implantation. Our in vitro assays verified that ECH-MS/ROP was able to enhance the adhesion and motility of Schwann cells. Besides, both in vitro and in vivo studies substantiated that ECH-MS/ROP stimulated myelinated axon regeneration through the MEK/ERK signaling pathway, thereby improving muscular denervation atrophy and facilitating functional recovery. Therefore, this study suggests that the ECH-MS/ROP dressing provides a promising strategy for treating diabetic PNI to facilitate nerve regeneration, functional recovery and pain relief.

Exosomes-loaded electroconductive nerve dressing for nerve regeneration and pain relief against diabetic peripheral nerve injury

Over the years, electroconductive hydrogels (ECHs) have been extensively applied for stimulating nerve regeneration and restoring locomotor function after peripheral nerve injury (PNI) with diabetes, given their favorable mechanical and electrical properties identical to endogenous nerve tissue. Nevertheless, PNI causes the loss of locomotor function and inflammatory pain, especially in diabetic patients. It has been established that bone marrow stem cells-derived exosomes (BMSCs-Exos) have analgesic, anti-inflammatory and tissue regeneration properties. Herein, we designed an ECH loaded with BMSCs-Exos (ECH-Exos) electroconductive nerve dressing to treat diabetic PNI to achieve functional recovery and pain relief. Given its potent adhesive and self-healing properties, this laminar dressing is convenient for the treatment of damaged nerve fibers by automatically wrapping around them to form a size-matched tube-like structure, avoiding the cumbersome implantation process. Our in vitro studies showed that ECH-Exos could facilitate the attachment and migration of Schwann cells. Meanwhile, Exos in this system could modulate M2 macrophage polarization via the NF-κB pathway, thereby attenuating inflammatory pain in diabetic PNI. Additionally, ECH-Exos enhanced myelinated axonal regeneration via the MEK/ERK pathway in vitro and in vivo, consequently ameliorating muscle denervation atrophy and further promoting functional restoration. Our findings suggest that the ECH-Exos system has huge prospects for nerve regeneration, functional restoration and pain relief in patients with diabetic PNI.

A Comprehensive Review of Cubital Tunnel Syndrome

Cubital Tunnel Syndrome (CuTS) is the compression of the ulnar nerve as it courses through the cubital tunnel near the elbow at the location colloquially referred to as the "funny bone". CuTS is the most commonly diagnosed mononeuropathy after carpal tunnel syndrome. Cubital tunnel syndrome can manifest as numbness, tingling, or pain in the ring/small fingers and dorsoulnar hand. Repetitive pressure, stretching, flexion, or trauma of the elbow joint are known causes of CuTS. Chronic ulnar nerve compression and CuTS, when left untreated, can lead to atrophy of the first dorsal interosseus muscle and affect one's quality of life to the point that they are no longer able to participate in daily activities involving fine motor function. It is estimated that up to 5.9% of the general population have had symptoms of CuTS. CuTS is underdiagnosed due to lack of seeking of treatment for symptoms. Compression or damage to the ulnar nerve is the main cause of symptoms experienced by an individual with CuTS. Repetitive elbow pressure or a history or elbow joint trauma or injury are additional known causes that can lead to CuTS. Common presentations of CuTS include paresthesia, clumsiness of the hand, hand atrophy and weakness. The earliest sign of CuTS is most commonly numbness and tingling of the ring and 5th finger. Older patients tend to present with motor symptoms of chronic onset; younger patients tend to have more acute symptoms. Pain and point tenderness at the medial elbow may also be seen. CuTS lacks universally agreed upon diagnostic and treatment algorithms. CuTS can be diagnosed by physical exam using Tinel's sign, flexion-compression tests, palpating the ulnar nerve for thickening presence of local tenderness along the nerve. Ultrasound and nerve conduction studies may be used in combination with physical exam for diagnosis. Conservative treatment for CuTS is almost always pursued before surgical treatment and includes elbow splints, braces, and night-gliding exercises. Surgical treatment may be pursued in severe CuTS refractory to conservative treatment. Surgical options include open and endoscopic in-situ decompression, medial epicondylectomy, and anterior transposition of the ulnar nerve. CuTS is a prevalent disease that, if left untreated, can significantly alter an individual's quality of life. Therefore, an accurate diagnosis and appropriate treatment is paramount in reducing further damage and preventing worsening or future symptoms.