Meiling, James B

Purpose: Hereditary transthyretin amyloidosis (ATTRv) is a progressive multisystem disease in which median mononeuropathy at the wrist (MNW) is common and often precedes systemic involvement. Nerve conduction studies (NCS) have historically been the gold standard for MNW, but neuromuscular ultrasound (NMUS) is complementary. The aim of this study was to compare NMUS with electrodiagnostic (EDX) testing for the diagnosis of MNW in patients with symptomatic ATTRv. Methods: A retrospective review was performed of patients 18 years and older with ATTRv confirmed by genetic testing who underwent both EDX testing and NMUS of the median nerve between 2019 and 2025. Demographic, NMUS, and EDX data were collected. Results: Data from 15 upper limbs in 10 patients were analyzed. Median nerve cross‐sectional area at the wrist was significantly greater than reference values ( P = 0.041). MNW was identified in 80% of wrists by NMUS and 100% by NCS, with no significant difference between modalities. Median nerve cross‐sectional area at the wrist did not significantly correlate with MNW severity determined by NCS ( r = −0.018; P = 0.941) or with any NCS parameters (all P > 0.080). Concurrent polyneuropathy was diagnosed in 60% of patients, but there was no association between polyneuropathy and MNW detection by either modality ( P > 0.197). Conclusions: NMUS and NCS demonstrate comparable diagnostic accuracy for MNW in ATTRv. Given its noninvasive nature and efficiency, NMUS may serve as an adjunct to classic EDX testing in this population.

Abstract Background Ultrasound (US)‐guided hydrodissection is a minimally invasive treatment for cubital tunnel syndrome (CuTS) with promising early results. However, data on patient‐perceived outcomes, durability of relief, and impact on surgical need remain limited. Objective To assess the effectiveness of US‐guided cubital tunnel hydrodissection in improving CuTS symptoms via patient‐centered outcomes. Design Retrospective chart review with cross‐sectional telephone follow‐up. Setting Quaternary medical center multidisciplinary outpatient hand clinic. Participants Seventeen patients (19 arms) with clinical CuTS who received US‐guided hydrodissection from one physician. Interventions Patients were contacted by telephone for cross‐sectional outcome assessment. Main Outcome Measures Patient‐reported improvements in weakness, paresthesias, and/or pain, percent pain relief, symptom improvement duration, adverse events, and Patient Global Impression of Change (PGIC) scores. Results At mean 7 ± 5 month follow‐up, improvement in weakness, paresthesia, and pain was reported in 12 (63%) extremities (95% confidence interval [CI] 41%–85%; p < .001) . Pain relief ≥50% occurred in 12 (63%) and ≥75% in 8 (42%) extremities, with mean duration 4 months. PGIC scores showed 14 (74%; 95% CI 54%–94%; p < .001) at least “minimally improved” and 8 (42%) (95% CI 20%–64%; p < .001) “much improved.” No adverse events occurred. Two patients without improvement underwent surgical decompression with anterior transposition at 1 and 3 months after hydrodissection, achieving 90%–100% pain relief and “much or very much improved” PGIC scores. Of 19 extremities, 7 (37%) were McGowan Grade I and 12 (63%) Grade II; none were Grade III. Grade II extremities showed significantly greater overall symptom relief ( p = .004) and pain relief ≥50% ( p = .004). PGIC scores did not differ significantly between grades (both p > .062). Conclusion US‐guided cubital tunnel hydrodissection was associated with meaningful symptom improvement and no adverse events. Limitations include small sample size, no control group, single operator, and potentially time‐limited relief. The procedure appears safe and a potential nonoperative treatment option.

ABSTRACT Introduction/Aims Ultrasound (US) guidance may be essential for accurate electromyography (EMG) needle placement in less‐commonly evaluated muscles, such as the extensor carpi radialis longus (ECRL) and brevis (ECRB), and particularly for identifying suitable donor muscles prior to tendon transfers to restore upper extremity function. Our primary aim was to compare the accuracy of trainee palpation‐guided versus first‐attempt US‐guided needle placement. Our secondary aim was to describe the locations of inaccurate needle placement. Methods Seven subjects each performed four needle placements (ECRL and ECRB, both palpation‐guided and US‐guided), totaling 28 placements into a cadaveric specimen. US‐guided needle placement was performed with one attempt after one live demonstration. Results No palpation‐guided ECRL attempts were accurate while only two of the palpation‐guided ECRB attempts were accurate. First‐attempt US‐guided needle placement was significantly more accurate overall (64.3% vs. 14.2%, p = 0.020), and specifically for ECRL (71.4% vs. 0%, p = 0.025). Combining palpation‐guided ECRL and ECRB attempts, the needle was inadvertently placed in the extensor digitorum communis (50%), extensor carpi ulnaris (16.7%), and brachioradialis (16.7%). Both US‐guided ECRL‐intended errors involved placing the needle into the adjacent ECRB. Discussion This study suggests that EMG needle placement into ECRL and ECRB by trainees may be more accurate with US guidance. Accurate preoperative individual needle assessments of both wrist extensors are essential for patients with tetraplegia considering reconstructive surgery to restore functional grasp and should be performed with US guidance.

ABSTRACT Introduction/Aims Patients with cervical spinal cord injury (SCI) prioritize recovery of upper extremity function. Upper extremity reconstruction can restore function in carefully selected individuals. Infralesional cord damage, observed below the neurological level of injury (NLI), may affect postoperative outcomes. We characterized the extent of infralesional lower motor neuron (LMN) injury in patients with traumatic cervical SCI. Methods Each patient underwent electromyography (EMG) of potential donor and recipient muscles based on preoperative clinical evaluation and specific candidacy for nerve and/or tendon transfers. The presence of infralesional pathologic insertional activity (IA), reduced motor unit potential (MUP) recruitment and/or neurogenic MUPs was assessed. The caudal‐most segment with infralesional LMN injury was determined. Inclusion criteria were patients with (1) traumatic cervical SCI; (2) injury ≥ 3 months duration; (3) preoperative planning EMG for nerve and/or tendon transfers. Results Forty‐eight upper extremity EMGs in 25 patients (68% male; mean age 39.5 years at injury) with traumatic cervical SCI were included. The NLI was at C7 or above in each patient, and 64% of SCIs were motor complete. Infralesional EMG abnormalities (median time from injury to EMG 466 days) were found a median of 3.0 (IQR 3.0–4.0) segments below the NLI. Three patients with an NLI as rostral as C1–C2 exhibited LMN injury seven segments below the NLI. Discussion In persons with traumatic cervical SCI, evidence of LMN injury may be observed several segments below the NLI. Defining the true extent of LMN involvement directly informs timing and selection of reconstructive procedures to maximize functional recovery.

Patients with traumatic brachial plexus injuries (TBPI) undergo clinical examination and electromyography (EMG) to characterize injury severity and localization. However, precise localization with EMG alone can be difficult when multiple injury sites are possible. Brachial plexus ultrasound (BPUS) allows direct visualization of the brachial plexus, a needed adjunct to EMG to reveal multiple sites of injury in TBPI. We summarize three cases of EMG-confirmed upper trunk TBPI which were clarified using BPUS to additionally involve electrically hidden injuries to the extraforaminal C5 and C6 nerve roots. BPUS demonstrated extensive scarring and focal enlargement of the upper trunk in each patient (all cross-sectional area [CSA] ≥24 mm 2 ). However, all patients also had C5 and C6 extraforaminal nerve root enlargement (all CSA ≥9 mm 2 and 12 mm 2 , respectively), revealing further neural involvement proximal to the upper trunk into the EMG “gray zone”– postganglionic, extraforaminal cervical nerve root injury which is clinically and electrodiagnostically indistinguishable from the plexus but anatomically and radiographically distinguishable on BPUS. Some EMG-identified upper trunk TBPI may have more proximal involvement of the contributing extraforaminal C5-6 nerve roots, an area electrically indistinguishable from an upper trunk TBPI without the assistance of advanced imaging.

ABSTRACT Introduction/Aims Neuromuscular ultrasound (NMUS) is becoming increasingly incorporated as a complementary tool in electrodiagnostic (EDX) medicine. Competency assessment is critical to ensure adequate quality, appropriate application, and accurate interpretation. The primary objective was to develop a competency‐based assessment tool of foundational NMUS skills among postgraduate medical trainees in a single center. Methods The assessment included written (28 multiple‐choice, short answer, or yes/no) questions and practical skills (15 prompts) sections recommended by a published consensus‐based survey to include the knowledge and skills necessary to achieve minimal competency for unsupervised practice of NMUS for common conditions. The written portion included interpretation of basic pathology. Core practical content focused on the most evaluated structures in the Mayo EDX laboratory: the median and ulnar nerves and diaphragm muscle. The practical portion was administered by a single examiner and scored with a five‐point competency‐based rating. Four experienced educators used the Angoff standard setting method to set passing scores for each section. Results Subjects included three EMG‐track clinical neurophysiology fellows who completed a NMUS lecture series with supervised hands‐on scanning and a 2‐week intra‐lab NMUS elective during fellowship. Composite scores ranged from 89% to 97%. All subjects met minimum passing scores for each section (77% and 88% for the knowledge and skills sections, respectively). Discussion This NMUS competency assessment was successfully implemented and may be incorporated into postgraduate medical trainee evaluation to ensure minimal competency in evaluation of carpal tunnel syndrome, ulnar neuropathy at the elbow, and diaphragm function. This effort integrates quality NMUS evaluations into clinical practice.

ABSTRACT Introduction/Aims In severe ulnar neuropathy at the elbow (UNE), occasionally surgeons will employ an end‐to‐side (ETS) nerve transfer of the anterior interosseous nerve (AIN) motor branch of pronator quadratus (PQ) to the ulnar motor component distally (AIN ETS). We used an ultrasound (US)‐guided near‐nerve monopolar needle stimulation of the AIN to determine the specific contribution of the transferred PQ motor branch to the ulnar‐innervated hand intrinsic muscles following AIN ETS in patients with UNE. Methods After inserting the monopolar needle under US guidance, direct stimulation of the AIN was performed while recording from the abductor digiti minimi (ADM), first dorsal interosseous (FDI), and flexor pollicis longus (FPL). The presence or absence of a compound muscle action potential (CMAP) was noted from each muscle. Results The technique was used in two patients with chronic UNE, one with a cubital tunnel decompression and AIN ETS and the other with a decompression alone. In the patient with decompression and AIN ETS, direct stimulation of the AIN revealed a low amplitude CMAP recorded from the FDI and FPL, suggesting AIN axonal contribution to FDI in the setting of prior AIN ETS. In the patient with decompression alone, near‐nerve stimulation generated an expected CMAP in the FPL but no response in the hand intrinsics. Discussion This study may demonstrate the utility of US‐guided near‐nerve monopolar needle AIN stimulation and suggests that it is a reliable technique to isolate the AIN contribution to hand intrinsic reinnervation following AIN ETS.