Carpal Tunnel Syndrome (CTS) is the most common nerve entrapment disorder to be diagnosed and treated globally, which is characterized by structural abnormalities at the compression site and impaired nerve conduction across the carpal tunnel (1, 2). The symptoms of CTS include tingling, numbness or pain at the distribution area of the median nerve in the hand with weakness of the thumb (3). Several risk factors contribute to its development, including genetics, metabolic disorders (such as diabetes, obesity), rheumatoid arthritis, acromegaly, hypothyroidism and hormonal fluctuations during pregnancy (4–8). The pathology of CTS is complicated (9), making it more difficult to predict the outcome (10–12). In detail, mild CTS is characterized by ischemia or a transient depolarization block which results in decreased conductivity of nerves (13, 14). Severe or prolonged compression will lead to focal complete demyelination in some nerve fibers and Wallerian degeneration with axonal loss in others, and a regenerative response in some neurons and related Schwann cells can also be observed at the same time (15, 16). Furthermore, pathological accumulation of amyloid fibrils in the carpal tunnel, often causing bilateral CTS, serves as an early sentinel sign of systemic amyloidosis (17, 18), and may precede the onset of cardiac amyloidosis by 5–10 years (19).

The current clinical approach to diagnosing CTS relies on a detailed medical history, physical examination, imaging techniques and electrodiagnostic (EDX) test (20, 21). Among these, nerve conduction studies (NCS) and electromyography (EMG) are crucial for diagnosing and grading CTS severity (20). These studies provide objective assessments of nerve function, with prolonged distal motor latency (DML) serving as a key indicator of nerve conduction damage (21). Based on the unique pathology of CTS, median nerve can exhibit immediate and long-term functional or structural changes after mini-open carpal tunnel release (Mini-OCTR), an effective and standardized procedure that can remove entrapment of median nerve achieve favorable outcomes in most cases (22–25). Although the time course of DML change has been reported (26–28), intraoperative (Intra-op) change in DML have been seldom researched, and their clinical value remains uncertain due to a lack of robust evidence linking these changes to postoperative (Post-op) outcomes (29, 30).

To clarify the clinical value of Intra-op changes in DML, we calculated latency recovery percent (LRP) based on preoperative (Pre-op) and Intra-op DML, and explore the prognostic value of LRP for predicting outcomes after Mini-OCTR. We hypothesized that a greater LRP would be associated with better outcomes and faster recovery after Mini-OCTR.

Current clinical evidence suggests that sensory function typically improves earlier than motor function, with some severe CTS cases requiring up to 6 months for motor recovery postoperatively (33). In our clinical practice, we observed that some patients experienced obvious relief from numbness or pain 1 day after Mini-OCTR, whereas others did not show immediate improvement. This variability in recovery may confuse patients and affect their satisfaction with the surgery. We noted that this immediate improvement might correlate with LRP. Despite the fact that Intra-op electrophysiology technique during CTR has been reported for decades (29, 30). LRP is still a parameter seldom mentioned in the literature with its clinical value remaining to be explained. Thus, we conducted a follow-up study of CTS cases for 6 months and found a correlation between LRP and sensory improvement at 1 day Post-op. We emphasized the importance of the immediate improvement in sensory function after surgery, because it can notably improve the patient’s life quality, which has been confirmed in previous studies (34, 35). In our clinical practice, most patients are satisfied with the surgical outcome because of good sleep quality at night without hand discomfort at 1 day Post-op. Conversely, if the surgery does not resolve their sleep issues, which can be their primary concern, they may perceive the procedure as ineffective, leading to their dissatisfaction with the Post-op outcomes.

Our study demonstrated that LRP is an independent predictor of sensory improvement at 1 day Post-op, which shed light on the real-time, Intra-op utility of EDX tests for outcome prediction after Mini-OCTR. Critically, an LR p value below 0.11 serves as an objective Intra-op warning sign of a high likelihood of suboptimal sensory recovery within the first 24 h after surgery. This immediate predictive capability offers substantial clinical utility beyond prognostication.

Firstly, the availability of LRP offers a potential opportunity for Intra-op reassessment. A low LRP value (< 0.11), particularly encountered in cases of severe or chronic CTS, might prompt the surgeon to re-evaluate the completeness of the median nerve decompression under the mini-open incision. This could involve meticulous inspection for any residual constriction at the distal edge of the transected transverse carpal ligament, ensuring maximal nerve decompression. Furthermore, this finding raises important questions for surgical technique refinement. In response to low LRP values, we have modified our technique to attempt a more thorough decompression, sometimes utilizing a longer incision than the standard mini-open approach. Most importantly, LRP enables surgeons to set precise expectations: patients with LR P < 0.11 can be proactively counseled that while decompression is complete, significant sensory relief may evolve gradually over days or weeks, mitigating anxiety and preventing dissatisfaction from unmet immediate hopes. Furthermore, identifying these patients allows for optimized Post-op care, such as scheduling early proactive follow-up to reinforce recovery timelines and manage concerns, ensuring targeted support reaches those at higher risk for early disappointment.

Thus, LRP transforms an Intra-op measurement into a tool for enhancing patient-centered care. By enabling real-time identification of patients prone to delayed sensory recovery, LRP facilitates critical actions: potential Intra-op checks, personalized expectation management, and tailored early support. This directly addresses a key driver of early Post-op concern—immediate symptom relief—significantly improving the initial patient experience and satisfaction.

Several machine learning or deep learning models on ultrasound images or EDX test have been developed for CTS diagnosis and severity classification so far (36–40). And prognosis models for CTS outcomes have also been previously reported, focusing primarily on BCTQ-SSS scores or VAS scores, which have achieved predictions comparable to those made by professional hand surgeons (10–12, 41–43). Furthermore, increasing studies have created models combined clinical data with histological and imaging results (44–47). These multi-classifier systems integrated by clinico-histology-genomic analysis makes clinical predictions more accurate and effective. Although such models often focus on the diagnosis and prognosis of diseases like cancer, this is also a direction for the development of CTS prognosis models. Given the current tendency that the importance of EDX tests is gradually being complemented by imaging studies (48), such model can become a comprehensive tool for clinical diagnosis and prognosis prediction.

While our analysis focused on demographic and electrodiagnostic predictors, it is important to acknowledge other perioperative variables that may contribute to early sensory outcomes. For instance, Post-op analgesic regimens such as gabapentinoids have been shown to significantly improve nocturnal symptom severity and sleep quality in patients with residual symptoms after CTR, though they do not affect functional status or daytime numbness (49). Similarly, adherence to Post-op immobilization (50) and specialized physical therapy (51) are other factors that may affect early axonal microenvironment recovery. Regarding surgical techniques, recent research has confirmed that the wide awake local anesthesia no tourniquet (WALANT) technique and local anesthetic with a tourniquet (LA-T) yield similar results in Post-op pain, suggesting that tourniquet time may not be a key determinant of pain (52). However, in the context of nerve function itself, tourniquet time can have a very significant impact due to ischemia, despite the similarity in Post-op pain outcomes. As these factors were standardized as part of our protocol, they were not specifically analyzed. We propose that future studies can systematically document surgical technical details, analgesic use patterns, and rehabilitation compliance. This would better contextualize LRP’s predictive role.

The most important limitation in our study was the small sample size. Next, our follow-up only captured the sensory improvement at 1 day and 6 months Post-op, limiting our exploration of the relationship between LRP and the time course of hand sensory and function recovery. Our results indicated no obvious correlation between LRP and recovery at the final follow-up point (6 months). Nevertheless, based on our 52-case cohort, sensory recovery at 1 day Post-op did not regress over the subsequent 6 months, suggesting that patients with high LRP might experience faster sensory recovery, but the difference of function recovery may diminish when the final follow-up time points is 6 months. Despite that short-term change in DML after CTR have been confirmed unconcerned with the long term outcomes in some studies (26), we believe the predictive value of LRP for long-term milestones such as earlier return to work or daily functional independence can be discovered with more follow-up time points and a larger cohort.