Brachial Plexus

Median nerve cross-sectional area (CSA) was used for screening and diagnosis of neuropathy, but few studies have suggested reference range. Hence, this systematic review was performed to evaluate a normative values of median nerve CSA at various landmarks of upper limb based on ultrasonography. PubMed and Web of science were used to search relevant articles from 2000 to 2020. Forty-one eligible articles (2504 nerves) were included to access median nerve CSA at different landmarks (mid-arm, elbow, mid-forearm, carpal tunnel (CT) inlet and CT outlet). Data was also stratified based on age, sex, ethnicity, geographical location, and method of measurement. Random effects model was used to calculate pooled weighted mean (95% confidence interval (CI), [upper bound, lower bound]) at mid-arm, elbow, mid-forearm, CT inlet and outlet which found to be 8.81 mm2, CI [8.10, 9.52]; 8.57 mm2 [8.00, 9.14]; 7.07 mm2 [6.41, 7.73]; 8.74 mm2 [8.45, 9.03] and 9.02 mm2 [8.08, 9.95] respectively. Median nerve CSA varies with age, geographical location, and sex at all landmarks. A low (I2 2 > 75%) was observed, indicating the variation among the included studies. These findings show that median nerve CSA is varying not only along its course but also in other sub-variables.

BackgroundThe complex anatomy of peripheral nerves has been traditionally investigated through histological microsections, with inherent limitations. We aimed to compare three-dimensional (3D) reconstructions of median and ulnar nerves acquired with tomographic high-resolution ultrasound (HRUS) and magnetic resonance microscopy (MRM) and assess their capacity to depict intraneural anatomy.MethodsThree fresh-frozen human upper extremity specimens were prepared for HRUS imaging by submersion in a water medium. The median and ulnar nerves were pierced with sutures to improve orientation during imaging. Peripheral nerve 3D HRUS scanning was performed on the mid-upper arm using a broadband linear probe (10-22 MHz) equipped with a tomographic 3D HRUS system. Following excision, nerves were cut into 16-mm segments and loaded into the MRM probe of a 9.4-T system (scanning time 27 h). Fascicle and nerve counting was performed to estimate the nerve volume, fascicle volume, fascicle count, and number of interfascicular connections. HRUS reconstructions employed artificial intelligence-based algorithms, while MRM reconstructions were generated using an open-source imaging software 3D slicer.ResultsCompared to MRM, 3D HRUS underestimated nerve volume by up to 22% and volume of all fascicles by up to 11%. Additionally, 3D HRUS depicted 6-60% fewer fascicles compared to MRM and visualized approximately half as many interfascicular connections.ConclusionMRM demonstrated a more detailed fascicular depiction compared to 3D HRUS, with a greater capacity for visualizing smaller fascicles. While 3D HRUS reconstructions can offer supplementary data in peripheral nerve assessment, their limitations in depicting interfascicular connections and small fascicles within clusters necessitate cautious interpretation.Clinical relevance statementAlthough 3D HRUS reconstructions can offer supplementary data in peripheral nerve assessment, even in intraoperative settings, their limitations in depicting interfascicular branches and small fascicles within clusters require cautious interpretation.Key points3D HRUS was limited in visualizing nerve interfascicular connections. MRM demonstrated better nerve fascicle depiction than 3D HRUS. MRM depicted more nerve interfascicular connections than 3D HRUS.

BackgroundIsolated radial nerve palsy is a debilitating injury that may potentially be reconstructed with either tendon transfers, nerve grafts, or nerve transfers. Currently, there is no consensus on the optimal technique for reconstruction. We performed a systematic review and analysis to determine which surgical intervention provides the best clinical outcomes.MethodsA systematic review was conducted according to PRISMA guidelines. Twenty-nine papers met inclusion criteria. Grading scales of function and strength were converted into a tripartite scoring system to compare outcomes between techniques. χ2 analyses were performed with a P value ResultsSeven hundred fifty-four patients were analyzed. Tendon transfers resulted in the highest percentage of good outcomes (82%) and the lowest percentage of poor outcomes (9%). Tendon transfers were superior to nerve grafts and nerve transfers for restoration of wrist extension. Nerve transfers for wrist extension were superior to nerve transfers for finger extension. Nerve grafts and nerve transfers had equivalent rates of good and poor clinical outcomes.ConclusionsThis study analyzed reported outcomes of tendon transfers, nerve grafts, and nerve transfers for reconstruction of isolated radial nerve palsy. On pooled analysis, tendon transfers had higher rates of superior clinical outcomes as compared with nerve transfers and nerve grafts. Tendon transfers should be considered first-line reconstruction for isolated radial nerve palsy as nerve-based reconstruction is less predictable and reproducible.

Introduction/aimsPatients with non-length-dependent neuropathy (NLDN) exhibit reduced sensory nerve action potential (SNAP) amplitudes in both lower and upper limbs. This study aimed to determine a threshold for the sural/radial amplitude ratio (SRAR) suggestive of NLDN.MethodsThis retrospective case-control study involved 60 patients with definite NLDN (sensory neuronopathy [SNN] or chronic inflammatory demyelinating polyradiculoneuropathy [CIDP]) and 30 patients with length-dependent neuropathy (LDN). The diagnostic performance of SRAR was evaluated using the area under the curve (AUC) of the modeled receiver operating characteristic (ROC) curve. The presence of a length-dependent electrodiagnostic (EDX) pattern, defined as a sural SNAP amplitude lower than the radial one, was evaluated in each group.ResultsSRAR could be calculated in 90/164 (54.9%) of patients screened. Among patients with NLDN, the median SRAR was 0.74 (IQR 0.50-1.00) compared to 0.17 (IQR 0.12-0.23) in patients with LDN. The ROC curve analysis for NLDN versus LDN yielded an AUC of 0.94 (95% CI, 0.883-0.979). The SRAR threshold of 0.33 provided a sensitivity of 84.4% (95% CI, 77.8%-90.9%), specificity of 86.9% (95% CI, 79.7%-94%). The length-dependent EDX pattern was observed in 100% (30/30) of LDN patients and 63% (38/60) of NLDN patients. Among these 38 patients with NLDN, SRAR exceeded 0.33 in 78.9% (30/38).DiscussionSRAR appears to be useful in the electrophysiological evaluation of neuropathies. In addition to usual diagnostic criteria, an SRAR > 0.33 may strongly suggest NLDN such as SNN or CIDP.