Search Results (39)

Background/Objectives: Closed reduction and percutaneous pinning is the standard surgical treatment for displaced pediatric supracondylar humerus fractures. Although crossed-pin fixation provides excellent biomechanical stability, medial pin insertion remains associated with the risk of iatrogenic ulnar nerve injury. The modified medial para-olecranon technique has been introduced as an alternative medial wire insertion strategy while preserving the principles of crossed-pin fixation. This study compared its clinical performance with conventional crossed pinning. Methods: A retrospective comparative cohort study was conducted at a tertiary referral trauma center between January 2017 and December 2024. Seventy children younger than 14 years with Gartland type II–IV supracondylar humerus fractures met the inclusion criteria. All patients treated with the modified medial para-olecranon technique (n = 35) were included. A comparison cohort of 35 patients treated with conventional crossed pinning was selected from 68 eligible conventionally treated patients by computer-generated random sampling stratified by Gartland type (frequency matching), after application of identical eligibility criteria. The primary outcome was functional outcome assessed using the Flynn criteria. Secondary outcomes included operative time, radiographic alignment, fracture union, and postoperative complications. Results: Baseline demographic and fracture characteristics were comparable between groups. Mean age was 6.7 ± 2.8 years in the modified medial para-olecranon group and 6.9 ± 2.6 years in the conventional crossed-pin group. The modified medial para-olecranon group had a lower mean Flynn score (6.80 ± 3.31 vs. 10.74 ± 3.70; mean difference, −3.94; 95% CI, −5.61 to −2.27; p < 0.001) and a higher proportion of excellent Flynn outcomes (77.1% vs. 28.6%). Operative time was shorter in the modified medial para-olecranon group (47.49 ± 7.50 vs. 66.00 ± 8.19 min; mean difference, −18.51 min; 95% CI, −22.26 to −14.76; p < 0.001). Fracture union occurred at a comparable time in both groups (27.71 ± 3.94 vs. 28.34 ± 4.12 days; mean difference, −0.63 days; 95% CI, −2.55 to 1.29), and postoperative Baumann angles were similar. No postoperative iatrogenic ulnar nerve injuries occurred in the modified medial para-olecranon group, whereas two occurred in the conventional crossed-pin group; both were transient sensory paraesthesia that resolved without exploration within six months. Overall complications occurred in 1 patient (2.9%) and 7 patients (20.0%), respectively (odds ratio, 0.17; 95% CI, 0.03 to 1.02; Fisher exact p = 0.055). Conclusions: In this retrospective comparative cohort, the modified medial para-olecranon technique was associated with favorable functional outcomes, shorter operative time, and fewer observed postoperative ulnar nerve injuries, although the difference in complications did not reach statistical significance, while maintaining comparable radiographic alignment and fracture healing. Because treatment was not randomized and potential confounders could not be adjusted for, these between-group differences should be interpreted as associations rather than as evidence of a causal treatment effect. Further prospective multicenter studies and dedicated anatomical investigations are required before broader recommendations can be made. Full article

Background: Transulnar access has emerged as a feasible alternative to transradial access for coronary angiography. However, the electrophysiological effects of proximal and distal transulnar approaches on ulnar nerve function remain insufficiently characterized. This study aimed to compare electrophysiological changes following proximal and distal transulnar coronary angiography and to evaluate their association with ulnar nerve involvement. Methods: This single-center retrospective observational study included 97 patients who underwent proximal (n = 56) or distal (n = 41) transulnar coronary angiography and developed post-procedural pain and/or paresthesia. Electroneuromyography and nerve conduction studies were performed before the procedure and at the fourth post-procedural week. Sensory and motor amplitudes, conduction velocities, and delta (Δ) changes were compared between groups. Generalized estimating equation analysis was additionally performed to evaluate longitudinal electrophysiological changes after adjustment for demographic and procedural variables. Results: No significant between-group differences were observed in pre- or post-procedural electrophysiological parameters. Although significant reductions in right ulnar sensory amplitude were observed over time, only 4 patients (4.1%) demonstrated post-procedural ulnar sensory amplitudes below the laboratory reference range, and no patient developed clinically significant ulnar neuropathy. Comparison of electrophysiological changes (Δ values) revealed no significant differences between proximal and distal transulnar access techniques. Generalized estimating equation analysis, adjusted for age and procedural characteristics, confirmed that the magnitude of electrophysiological changes over time was comparable between the two groups. Conclusions: Both proximal and distal transulnar access may be associated with mild, predominantly sensory, subclinical ulnar nerve involvement. However, distal transulnar access did not result in greater electrophysiological deterioration or additional neurological risk compared with proximal access. Full article

Background: Predicting functional recovery after selective nerve transfer remains challenging. Intraoperative nerve action potential (NAP) recording is widely used to confirm axonal continuity in peripheral nerve surgery; however, its quantitative prognostic value in selective nerve transfer has not been clearly established. This study evaluated whether intraoperative donor fascicle NAP amplitude predicts functional recovery following selective ulnar-to-musculocutaneous nerve transfer (Oberlin procedure) for restoration of elbow flexion. Methods: This retrospective exploratory observational study included 20 patients who underwent selective ulnar-to-musculocutaneous nerve transfer (Oberlin procedure) with standardized intraoperative neurophysiological mapping and quantitative donor fascicle NAP recording. Functional outcome specific to elbow flexion was assessed at last follow-up using the Medical Research Council (MRC) grading system. Time to first electromyographic evidence of biceps reinnervation was recorded. Associations between intraoperative NAP amplitude and functional, temporal, and clinical variables were analyzed using Spearman’s rank correlation coefficient and non-parametric tests. Results: Donor NAP amplitude demonstrated substantial interindividual variability (range 60–400 µV; median 137.5 µV, IQR 87.5–200 µV). No significant associations were observed between NAP amplitude and final MRC grade (ρ = −0.103; p = 0.666), time to electromyographic reinnervation (days: ρ = −0.123; p = 0.617), patient age, or time from injury to surgery. A moderate negative correlation between NAP amplitude and lesion severity was observed but did not reach statistical significance in this small cohort (ρ = −0.419; p = 0.0659). In contrast, shorter time to electromyographic reinnervation was significantly associated with improved final functional outcome (ρ = −0.559; p = 0.013). No patient reported postoperative hand weakness. Conclusions: In this exploratory cohort, intraoperative donor NAP amplitude was not associated with time to electromyographic reinnervation or final elbow flexion strength following selective ulnar-to-musculocutaneous nerve transfer. Although intraoperative NAP mapping remains essential to confirm axonal continuity and conduction viability of the donor fascicle, NAP amplitude did not demonstrate prognostic value in this cohort and should be interpreted cautiously as an isolated predictor of functional recovery, particularly given the limited sample size and exploratory design. These findings suggest that recovery after selective nerve transfer may be influenced by broader biological determinants, including regenerative timing, rather than by isolated intraoperative amplitude metrics. Full article

Background/Objectives: Selective transfer of an ulnar nerve fascicle to the motor branch of the musculocutaneous nerve (Oberlin technique) is widely used to restore elbow flexion following upper brachial plexus injury. Intraoperative neurophysiological mapping allows quantitative recording of compound muscle action potentials (CMAPs) during donor fascicle selection; however, its prognostic relevance remains unclear. This study evaluated whether intraoperative flexor carpi ulnaris (FCU) CMAP amplitude is associated with time to electromyographic reinnervation of the biceps brachii and with final functional outcomes. Methods: A retrospective observational study was conducted including patients who underwent selective nerve transfer to the biceps brachii between 2006 and 2025 at two tertiary referral centers. Donor fascicles were selected using intraoperative neurophysiological mapping with quantitative CMAP recordings from three ulnar-innervated muscles. Primary outcomes were time to electromyographic evidence of reinnervation and final elbow flexion strength assessed using the British Medical Research Council grading system. Associations were analyzed using nonparametric statistical methods. Results: Twenty patients met the inclusion criteria. Higher intraoperative FCU CMAP amplitudes were associated with a shorter time to electromyographic reinnervation (Spearman ρ = −0.572, p = 0.0106). No association was observed between CMAP amplitude and final elbow flexion strength (Spearman ρ = −0.168, p = 0.479), or between time to reinnervation and final functional outcome (Spearman ρ = −0.276, p = 0.253). A positive association was found between the injury-to-surgery interval and intraoperative CMAP amplitude (Spearman ρ = 0.681, p = 0.000943). Conclusions: The intraoperative FCU CMAP amplitude facilitates objective donor fascicle selection and is associated with earlier electromyographic reinnervation. Nevertheless, it was not associated with final elbow flexion strength in this cohort and should be interpreted as a technical adjunct rather than a standalone prognostic indicator. Functional recovery following nerve transfer appears to reflect multifactorial biological and temporal determinants beyond a single intraoperative neurophysiological measurement. These findings should be interpreted cautiously given the limited sample size. Full article

This case highlights the diagnostic value of high-resolution ultrasonography in identifying postoperative injury of the posterior branch of the medial antebrachial cutaneous nerve (MABCN) following cubital tunnel surgery. A 45-year-old man developed localized pain, warmth, and paresthesia extending from the medial epicondyle to the proximal anterior forearm one month after ulnar nerve decompression and anterior transposition. Physical examination revealed focal allodynia and a positive Tinel sign. Because previous surgery may substantially alter the anatomical location of the surrounding nerves, electrodiagnostic localization can be technically challenging and less reliable. Ultrasonography therefore played a key diagnostic role. The images demonstrated the normal sonoanatomy of the MABCN and its anatomical relationship with the basilic vein and ulnar nerve, followed by pathologic findings of focal enlargement of the posterior branch adjacent to postoperative scar tissue. These imaging features, together with a positive sonographic Tinel sign, supported the diagnosis of localized nerve irritation. Ultrasound-guided hydrodissection using 5% dextrose and methylcobalamin resulted in marked clinical improvement, with the Visual Analog Scale pain score decreasing from 9 to 2. This case is particularly illustrative because postoperative injury of the MABCN may mimic recurrent cubital tunnel syndrome yet typically produces purely sensory symptoms confined to the medial elbow region. Targeted ultrasonographic evaluation can reveal subtle postoperative nerve pathology and guide effective ultrasound-guided intervention. Full article

Background and Clinical Significance: Radiocarpal fracture dislocations (RCFDs) are rare injuries of the wrist, while open RCFDs represent a small subgroup of these injuries. Limited data exists regarding the optimal method for their management. Our study’s objective is to present a rare case of an open (Gustilo–Anderson type II) dorsal radiocarpal dislocation in combination with fracture of the radial and ulnar styloid and neurologic deficits (superficial radial, median and ulnar nerve), which was treated with external fixation and Kirshner wire pinning. External fixation and Kirshner wire pinning could be a viable surgical option for complicated open RCFD. Case Presentation: Adequate reduction and ligamentotaxis using an external fixation were achieved, while the radial styloid fracture and the distal radioulnar joint (DRJ) were stabilized with Kirshner wires. Postoperative radiographs and clinical evaluation confirmed satisfactory reduction in the right wrist, without signs of intercarpal instability. Total nerve recovery was observed 6 months postoperatively and the patient was able to return to his previous occupation. At the final follow-up (4 years), the Visual Analogue Scale score was 1/10 and the Quick Dash score was 11/100 with good range of motion (flexion: 0–75°, extension: 0–70°, pronation: 0–80°, supination: 0–80°) of the affected wrist, although progressive wrist arthritis and ulnar migration was seen in the plain X-rays. Conclusions: Surgical treatment of RCFDs is required for complex or unstable fractures/dislocations to avoid possible complications, such as intercarpal instability. Full article

Anatomical variations of the ulnar nerve at the wrist are uncommon and may lead to diagnostic confusion or iatrogenic injury if unrecognized. We present an ultrasound-based identification of a rare transligamentous ulnar nerve sensory branch entrapment in an elderly male with chronic ulnar-sided hand paresthesia. High-resolution ultrasonography revealed an aberrant sensory branch deviating from the ulnar nerve, piercing the palmar carpal ligament, and coursing superficially rather than entering Guyon’s canal. Further assessment demonstrated focal nerve flattening within the ligament with proximal enlargement, consistent with entrapment. This case highlights the value of ultrasound in detecting rare peripheral nerve variants and their entrapments. Therefore, it is also noteworthy to extend the sonographic evaluation beyond conventional entrapment sites at the wrist. Full article

Background: Peripheral nerve injuries affect a significant proportion of patients with upper extremity trauma, with transections frequently requiring surgical intervention. While direct repair (DR) remains the historical standard, connector-assisted repair (CAR) has been proposed to improve functional outcomes by addressing limitations inherent to DR, such as fascicular misalignment and tension at the repair site. Objectives: The purpose of this systematic review is to evaluate and compare the clinical effectiveness and complication rates of DR versus CAR in upper extremity peripheral nerve injuries. Methods: A systematic search of the PubMed, Scopus, and Ovid MEDLINE databases was conducted for clinical studies published between January 1980 and August 2025 that reported sensory outcomes after DR or CAR for peripheral nerve injuries in the upper limb. Studies were included if sensory outcomes could be categorized using the Medical Research Council Classification (MRCC) scale. The primary outcome was the rate of meaningful sensory recovery (MR), defined as MRCC ≥ S3, with a secondary threshold of MRCC ≥ S3+. Secondary outcomes included postoperative neuroma formation, cold intolerance, pain scores, altered sensation, and revision rate. Statistical analysis was performed using two-sided Fisher exact tests and unpaired t-tests, with p < 0.05 considered significant. Results: A total of 441 patients (DR) and 338 (CAR) were included, with mean ages of 34.2 and 37.3 years and a male predominance (79.7% vs. 73.8%). Overall, 705 nerves in DR and 436 in CAR were treated, mainly digital (86.4% vs. 79.9%), followed by ulnar, median, and radial. Sensory nerves predominated (86.4% vs. 81.6%), with mixed nerves more frequent in CAR (22.5%). Most injuries were Grade I (73% vs. 72.1%), with similar rates of Grades II–III. In the CAR group, the most used conduit was collagen type I (58.3%). Sensory recovery (S3+ and S4) was higher in CAR (69.3%) than DR (50.8%), while DR showed lower two-point discrimination >15 mm. Motor recovery was limited, with better values in DR. DASH scores averaged 13.2 (DR) and 18.2 (CAR), with follow-up of 26 and 23.8 months. Complications were more frequent in DR for cold intolerance, altered sensation, and pain, whereas neuromas, revisions, and fistulas were higher in CAR. Conclusions: Connector-assisted repair demonstrates better sensory recovery and less cold intolerance than DR in small-gap upper-extremity nerve injuries but with higher post-interventional risks and costs. DR remains effective for closely approximated nerves. Randomized trials are warranted, as current evidence is heterogeneous and mostly observational. Full article

Background: Non-transected and partially transected peripheral nerve injuries (neuromas-in-continuity) are relatively common but understudied. Their optimal surgical management and expected outcomes remain unclear. We conducted a literature review of surgical repairs in such lesions and illustrate a case to guide decision-making. Systematic searches of PubMed and Google Scholar identified 70 eligible reports (Level I = 2, Level II = 5, Level III = 37, Level IV = 20, Level V = 4). Across studies, neurolysis of NAP-positive lesions often restored antigravity strength, while direct repair or grafting of nonconductive segments yielded meaningful recovery in ~75%. After neurolysis or reconstruction, ~77–92% of brachial plexus/axillary neuromas-in-continuity reached LSUHSC Grade ≥3. Median/ulnar lesions treated with neurolysis, biologic/vascularized coverage, or reconstruction showed reliable pain relief but variable sensory/motor recovery. Radial/PIN lesions improved in some series irrespective of NAPs. Earlier intervention, shorter gaps, distal sites, and younger age correlated with superior outcomes. Meanwhile, prolonged observation risking end-organ atrophy degraded results. Adjuncts such as electrical stimulation and wraps may aid reinnervation or reduce scarring, though high-quality evidence is limited. Conclusions: For non-transected and partially transected PNIs, a pragmatic approach emerges: Observe low-grade injuries with serial examinations. Explore early if recovery stalls (≈3–6 months). Use NAP-guided neurolysis for conductive lesions. Perform tension-free repair or grafting for nonconductive segments, adding anti-adhesive coverage when appropriate. Standardized reporting and prospective trials are needed to refine timing, technique selection, and patient-reported outcomes. Full article

Introduction: Post-traumatic and post-surgical ulnar nerve neuropathies at the elbow and wrist remain challenging conditions often associated with significant sensory and motor impairment. Traditional approaches such as neurolysis alone may be insufficient, especially in complex or recurrent cases. Adipofascial flaps have shown promising outcomes in peripheral nerve surgery. The aim of this study was to evaluate the outcomes of 13 patients with severe ulnar neuropathies who were treated with a size- and shape-personalized adipofascial flap for nerve coverage. Materials and Methods: We retrospectively analyzed 13 patients treated between May 2020 and May 2024 for severe post-traumatic or post-surgical ulnar neuropathies. All underwent surgical decompression, external neurolysis, and adipofascial flap coverage. Pre- and postoperative outcomes were assessed with clinical and neurological evaluations and using the QuickDASH and NRS pain scores. Discussion: All patients showed improvement in pain and sensory-motor function, including those with complications, supporting the role of flap coverage in neuroprotection. This is the first study to describe the use of adipofascial flaps for pseudo-palsy and painful neuroma-in-continuity of the ulnar nerve at the elbow and wrist level. Conclusions: Adipofascial flaps represent a safe, technically feasible, and effective option in complex ulnar nerve injuries, providing both mechanical and biological support. Despite the small cohort, the results suggest strong clinical potential across varied injury patterns. Full article

Background: Displaced pediatric supracondylar humerus fractures (PSHFs) commonly require surgical treatment. Medial pin placement can cause iatrogenic ulnar nerve injury. This study presents a modified, step-by-step cross-pinning technique for PSHFs designed to avoid iatrogenic ulnar nerve injury. Methods: We retrospectively included patients with PSHF (Gartland types III or IV) who underwent closed reduction and percutaneous cross-pinning at our hospital from June 2014 to December 2024. Demographic data, fracture type, and preoperative and postoperative neurological deficits were recorded. Results: A total of 40 patients (16 boys and 24 girls) with a mean age of 6.6 ± 2.2 years (range, 2–14) were included. Most injuries were type III (35/40; 87.5%), whereas five patients (12.5%) had type IV injuries. Our technique resulted in no new cases of postoperative ulnar neuropathy. Conclusions: This study describes a modified medial pin insertion technique for unstable PSHFs. Careful attention to medial pin placement can minimize iatrogenic ulnar nerve injury. Full article

Background: Fractures of the distal humerus (DHFs) represent challenging intra-articular injuries that are often followed by postoperative complications, most notably ulnar neuropathy. There is still debate regarding the best method of handling the ulnar nerve during open reduction and internal fixation (ORIF). Objective: The primary objective was to evaluate the incidence of postoperative ulnar neuropathy (UN) in patients who underwent open reduction and internal fixation (ORIF) for DHFs, comparing anterior transposition (AT) with in situ decompression (ISD) of the ulnar nerve. Additionally, we investigated the influence of AT on individuals presenting with preoperative UN. Methods: A retrospective review was conducted on 68 patients (26 females and 42 males; mean age: 46.3 years) who underwent ORIF for intra-articular DHF between 2018 and 2022. Patients were divided into two groups: anterior transposition (n = 14) and in situ decompression (n = 54). Ulnar neuropathy was evaluated using the modified McGowan classification, and radiographic outcomes were assessed with AO/OTA fracture classification. Results: Sixty-eight patients (26F/42M) were included. The mean age was 46.3 years (20–77 years) and the mean follow-up time was 53 months (36–76 months). The postoperative UN incidence was 30.8% (21/68). Neuropathy was significantly higher in the transposition group compared to in situ decompression (57.1% vs. 24%; p = 0.012). Olecranon osteotomy (36.3% vs. 20%; p = 0.042) and parallel plate configuration (33.3% vs. 12.5%; p = 0.037) were also associated with increased neuropathy risk. Among patients with preoperative ulnar neuropathy (n = 12), functional recovery was more favorable with transposition, where 71% experienced full resolution compared to 60% in the in situ group. Conclusions: Routine anterior transposition of the ulnar nerve during ORIF for DHF is associated with an increased risk of postoperative neuropathy and should be avoided in patients without preoperative symptoms. However, transposition appears beneficial in patients with pre-existing ulnar neuropathy. Surgeons should individualize ulnar nerve management to balance surgical risks and neurological outcomes. Full article

Background: The consequences of median nerve compression at the carpal tunnel level require a precise diagnostic evaluation before a frequently applied surgical intervention. Positive Tinel or Phalen signs are not always related to abnormal results in electroneurographic examinations of sensory and motor nerve fibers, which are intended to confirm final diagnoses, thereby confusing both surgeons and neurophysiologists. In the face of contradictory data, this study aims to reinvestigate these correlations in a randomly chosen population of patients with a primary diagnosis of carpal tunnel syndrome (CTS). Methods: Seventy-five randomly chosen patients with clinically detected CTS underwent neurophysiological studies of median nerve sensory (SNAP) and motor (CMAP) fibers conduction at the wrist. Both the median and ulnar nerves were assessed to reduce the risk of misinterpretation related to anatomical variations. Results: This study provides evidence on the relatively high utility of Phalen’s test in the early clinical detection of CTS within a general population of patients, whose positive results moderately correlate (rho = −0.327) with abnormalities in amplitudes rather than the distal latency parameters of SNAP recordings. The axonal injury type is more distinct than slowing-down impulses at the wrist following compression of the sensory nerve fibers in the early course of CTS. Positive Tinel’s test results are useful in diagnosing CTS patients with advanced axonal and demyelinating changes in the motor fibers at the wrist, which weakly correlate with prolonged latency and decreased amplitude in SNAP recordings (rho = −0.214 and rho = −0.235, respectively), but not with abnormalities in recordings of both amplitudes and latencies in CMAP electroneurography. Conclusions: The correlations between clinical signs and neurophysiological findings in CTS indicate that provocative tests, such as Phalen’s and Tinel’s, have limited diagnostic value, demonstrating only weak-to-moderate associations with neural conduction parameters. A positive Tinel’s sign should be regarded mainly as a marker of severe or chronic sensory impairment, often accompanied by motor fibers involvement in advanced pathological stages, rather than as an indicator of motor damage alone. Nerve conduction studies remain essential for confirming CTS, assessing its severity, and guiding treatment decisions, including surgical qualification. The presented correlation of clinical and functional neurophysiological results in CTS diagnosis allows us not only to specify the source and severity of the pathology of the median nerve fibers but also may influence the personalization of physiotherapeutic and surgical treatments. Full article

Background and Clinical Significance: Non-palpable migrated contraceptive implants pose significant challenges for removal and are associated with neurovascular complications. Traditional open surgery near nerves is associated with postoperative morbidity. Migrated or deeply embedded implants near critical structures can result in severe complications, such as neuropathy, and their removal typically requires open surgical intervention. Case Presentation: We report a novel, minimally invasive, ultrasound (US)-guided technique for removing a migrated etonogestrel Implanon^® implant that caused ulnar neuropathy. A 38-year-old woman presented with severe neuropathic pain and paresthesia (NPRS 10/10; QuickDASH 55) along her left ulnar nerve following multiple failed removal attempts that induced deep migration. US confirmed the proximity of the implant to the ulnar nerve. Initial US-guided removal exacerbated her symptoms. Hydrodissection (HD) with 50 mL of 5% dextrose in water (D5W) without local anesthetic (LA) was performed to reduce inflammation and achieve separation. The implant migrated proximally during extraction. An additional HD with 50 mL of D5W without LA distally repositioned the implant. Percutaneous stabilization using a 25-gauge needle enabled secure removal. The intact 4 cm implant was extracted under real-time US guidance without open surgery. The patient experienced immediate symptom relief (NPRS 2/10; QuickDASH 4.5 at one month) and full resolution (NPRS 0/10; QuickDASH 0) with no motor deficits at one year. Conclusions: This case represents the first documented percutaneous removal of a nerve-adherent implant using combined US-guided D5W HD and needle stabilization, marking a paradigm shift in the management of such cases. This approach confirms the safety of US-guided foreign body removal using HD for nerve-adjacent implants and demonstrates the efficacy of combining D5W HD with needle stabilization. Surgical morbidity was avoided, while excellent long-term outcomes were achieved. Full article

Background/Objectives: The Wartenberg sign is a diagnostic feature of ulnar nerve neuropathy. It results from unbalanced activity of the abductor digiti minimi (ADM) and extensor digiti minimi (EDM) muscles secondary to weakness of the third palmar interosseous muscle. Rarely, this sign may occur in the absence of an underlying ulnar neuropathy, which we refer to as the “pseudo Wartenberg sign” (PWS). Methods: This is a retrospective review of 10 patients manifesting an inability to adduct the little finger towards the ring finger with no evidence of an ulnar neuropathy. We describe the clinical and electrodiagnostic (EDX) findings in these patients and discuss the pathophysiologic basis of PWS. Results: The most common cause was an injury in five (50.0%) patients: avulsion of the third volar interosseous muscle in two (20.0%), contracture of the ADM muscle in one (10.0%), and trauma-related dystonia in two (20.0%). The most frequent mechanism of PWS was focal dystonia of specific hand muscles in seven (70.0%) patients. Needle electromyography (EMG) demonstrated no denervation changes in ulnar nerve-innervated hand muscles; the motor and sensory conduction was normal in the ulnar nerve in all patients. Four (40.0%) patients underwent ultrasound studies, with a hyperechoic, avulsed third volar interosseous muscle in one, a hyperechoic and atrophic ADM muscle in one, normal hypothenar and extensor muscles in one, and a normal hypothenar muscle in one. Conclusions: Neurologists, neurosurgeons, and hand and orthopedic surgeons should be aware of the rare cases in which the inability to adduct the little finger may occur in the absence of ulnar neuropathy and look for other causes like avulsion of the third palmar interosseus muscle or focal hand dystonia. Full article