June 20, 2026
For patients with cervical spinal cord injury (SCI) and tetraplegia, restoring hand grasp and pinch function is still a primary goal. Tendon transfer offers faster functional recovery compared with nerve transfer, typically achieving clinically meaningful improvement within 3 to 4 months. Appropriate donor muscle selection is critical to avoid loss of residual function and optimize outcomes. Surgeons must evaluate the patient's extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB) muscles to determine whether one or both are functional.
"In the past, it's been difficult to accurately assess the functional status of the ECRL and ECRB based on a clinical exam alone," says Kitty Y. Wu, M.D., a hand and reconstructive surgeon at Mayo Clinic in Rochester, Minnesota.
"Furthermore, it's challenging to distinguish between the two wrist extensors due to their small size and anatomical proximity utilizing standard EMG techniques," explains James B. Meiling, D.O., a physiatrist and neuromuscular physician at Mayo Clinic in Rochester, Minnesota.
"Using ultrasound-guided EMG was critical in preoperative planning to determine prospective tendon transfer candidacy."
Dr. Meiling, Dr. Wu and colleagues have introduced ultrasound (US)-guided needle electromyography (EMG) to evaluate the ECRL and ECRB with improved precision. This novel technique helps determine a patient's candidacy for tendon transfer.
Using US guidance to identify and assess the electrophysiologic health of wrist extensors
The ECRL and ECRB are active wrist extensors. If both are functional, surgeons can safely use one as a donor for a tendon transfer without sacrificing wrist extension.
However, if only one is functional and inadvertently harvested, the patient can lose all wrist extension and tenodesis — a catastrophic outcome for patients with tetraplegia.
Making this distinction is critical in selecting the right candidates for tendon transfer.
"Preoperative US-guided needle EMG is vital in determining the electrophysiologic health of potential muscles and nerves used in these surgeries," Dr. Meiling says. "But EMG with surface palpation cannot reliably identify the individual wrist extensors because they're small, proximal, overlapping muscles." In addition, patients with tetraplegia cannot voluntarily activate these muscles, further reducing accuracy in muscle identification.
Using ultrasound guidance can ensure precise needle placement, particularly for atrophied plegic muscles.
In 2025, Dr. Meiling, Dr. Wu and other Mayo Clinic colleagues published a case report in the American Journal of Physical Medicine & Rehabilitation describing the technique. Preoperative US-guided needle EMG can accurately differentiate between and independently assess electrical activity in the ECRL and ECRB. This allows reconstructive surgeons to precisely plan tendon transfer surgery.
Preoperative planning for tendon transfer surgery
Using US-guided needle EMG to find and test the ECRL and ECRB muscles — and, in some cases, the brachioradialis (BR) — can improve diagnostic precision and functional outcomes.
Dr. Wu and Dr. Meiling followed up their 2025 publication with a letter to the editor of the Journal of Spinal Cord Medicine, published in March 2026. In it, they presented three clinical cases of patients with motor-complete cervical SCI who had impaired hand function.
Dr. Meiling used US-guided needle EMG to evaluate donor muscles before surgery. And Dr. Wu performed successful BR-to-flexor pollicis longus and ECRL-to-flexor digitorum profundus tendon transfers on each patient.
"All three patients had significant improvement in functional grasp and pinch at follow-up 2 to 4 months postoperatively," Dr. Wu says. "Using ultrasound-guided EMG was critical in preoperative planning to determine prospective tendon transfer candidacy."
The future of US-guided EMG
Neuromuscular US is already a proven diagnostic complement to nerve conduction studies and needle EMG. US-guided EMG is a natural extension of modern electrodiagnostic practice and a useful integration into preoperative workflows in centers with neuromuscular US expertise, such as Mayo Clinic.
Collaboration between electrodiagnostic physicians and hand surgeons is essential to align diagnostic findings with surgical planning. Mayo Clinic physicians are conducting additional research to determine which other muscles would benefit most from preoperative US-guided EMG to help predict successful postoperative outcomes.
For more information
Meiling JB, et al. Ultrasound-guided needle electromyography of the extensor carpi radialis longus and brevis muscles for preoperative tendon transfer planning in cervical spinal cord injuries: Technique description and case report. American Journal of Physical Medicine & Rehabilitation. 2025;104:1064.
Meiling JB, et al. Preoperative needle electromyography with ultrasound-guidance to optimize functional hand grasp and pinch outcomes with tendon transfers in cervical spinal cord injuries. The Journal of Spinal Cord Medicine. 2026:1.
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