Introduction/Aims: Electrophysiological and clinical Correlation of pre- and post-operative analysis in BPI surgical management through the use of Neurolysis.

Methods: An ambilective quasi-experimental analytical study was carried out. In order to determine the prognostic value of the preoperative electrophysiological analysis in the clinical and functional recovery after surgical intervention. the study was approved by the Hospital's research and bioethics committee (DI/16/403/03/152), the informed consents were obtained and signed by all the patients included. A Wilcoxon test was performed in search of significant clinical and functional changes after surgery, and a Spearman Correlation test was realized between the preoperative electrophysiological variables and postoperative clinical and functional outcomes. Value α = 0.05 and β = 0.01.

Results: Twenty patients were studied. Postoperative clinical evaluation showed significant changes in terms of pain (∆79.95%, p = 0.034), upper limb functional recovery (∆31.53%, p = 0.029), and subjective perception of general health (∆15.83%, p = 0.007). Correlation analysis showed that the stronger relationship was observed in the association between fibrillation potentials with the recovery of postoperative pain (R = 0.997, p = <0.001), polyphasic units with the increase in the patient's subjective perception of their general health measured (R = 0.999, p <0.001), and the amplitude of the sensitive nerve action potential with sensorial recovery (R = 0.942, p = 0.009).

Discussion/Conclusion: Neurolysis demonstrated changes in pain and functional recovery, related to the presence of polyphasic units and fibrillation potentials. The prognostic value of electrophysiology in postoperative clinical recovery is uncertain, this study introduces the possibility of observing preoperative electrophysiological studies as a prognostic tool for clinical and functional recovery in the surgical management of BPI.

The clinical evaluation was carried out by a structured questionnaire at consultation. The degree of motor and sensory recovery was classified according to the BMRC scales. The decrease in pain was classified according to VAS, and functional recovery was evaluated by applying the DASH and SF-36 questionnaires. The electrophysiological evaluation was carried out through the use of EMG and NC studies (Cadwell Sierra Wave EMG System, Nihon Kohden Neuropack M1 MEB-9200, and XLTEK XCalibur LT 10328 EMG Unit). The tests performed were sensory and motor nerve conductions, and needle qualitative EMG. The NC analysis was focused on evaluating the amplitudes and latencies of the sensory nerve action potential (SNAP) and compound muscle action potential (CMAP), for its analysis the percentage of axonal injury was calculated. This percentage was calculated using a formula (U-A / U X 100), where "U" corresponds to the values ​​of the unaffected limb and "A" to the values ​​of the affected limb (reference of the % axonal injury) [7].  Regarding the EMG study, the characteristics of the graphs were analyzed in search of denervation data (fibrillation Potentials and positive sharp waves), and reinnervation data (polyphasic units and MUAP's recruitment). Polyphasic units were evaluated as a binomial variable (presence/absence). An average value of the other variables obtained by EMG was obtained using ordinal subjective scales (full, reduce, discrete or none) for MUAPS's recruitment and an ordinal scale (1+ (reproducible potentials in more than 1 area) to 4+ (obliterating the baselines)) for fibrillation potentials and positive sharp waves. In order to establish significant changes after surgery in clinical and electrophysiological variables, a Wilcoxon test was performed to establish the relationship between the preoperative electrophysiological variables and the postoperative clinical variables, a Spearman Correlation test was performed looking for the electrophysiological variables that had a stronger relationship with each of the clinical and functional outcomes evaluated. Statistical comparisons of the outcomes involved were performed using SPSS 25.0 for Windows software (SPSS, Inc., Chicago, IL). In order to establish significant changes after surgery in clinical and electrophysiological variables, a Wilcoxon test was performed to establish the relationship between the preoperative electrophysiological variables and the postoperative clinical variables, a Spearman Correlation test was performed looking for the electrophysiological variables that had a stronger relationship with each of the clinical and functional outcomes evaluated. Statistical comparisons of the outcomes involved were performed using SPSS 25.0 for Windows software (SPSS, Inc., Chicago, IL). 

The database is divided into three relevant sections; 
1.- Clinical-Electrophysiological Correlation Data. 
2.- Clinical Outcomes After Surgery.  
3.- Demographic and Procedural Characteristics.