Luetmer, Marianne T.

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 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.

Purpose: Neuromuscular ultrasound, including cross-sectional area measurements, adds diagnostic value to the clinical and electrodiagnosis evaluation of ulnar neuropathy at the elbow. Previously published reference values for ulnar nerve size vary widely. Our objective was to establish age-specific reference values for ulnar nerve cross-sectional area at multiple sites in asymptomatic adults for our laboratory. Methods: Healthy adult subjects without neuromuscular symptoms or disease were recruited from our tertiary referral electromyogram laboratory and staff. Ulnar nerve cross-sectional area measurements were made in short axis at the wrist, forearm, cubital tunnel, retrocondylar groove, 2 cm proximal to the medial epicondyle, and mid-upper arm with the elbow flexed to 90°. Dynamic neuromuscular ultrasound evaluated for subluxation and dislocation at the medial epicondyle. Results were stratified by age group (younger than 40, 40–60, and older than 60 years) with at least 20 subjects per sex per group, as well as by sex, body mass index, and handedness. The upper limit of normal was established as two standard deviations above the mean. Results: One hundred forty-two subjects (ages 18–84, mean 47.7 years) were included. Cross-sectional area significantly increased with age at all sites except the wrist. Cross-sectional area cut-offs at the retrocondylar groove were 10.0, 10.9, and 11.4 mm 2 , respectively, by age group. Ratios comparing retrocondylar groove and cubital tunnel to arm and forearm were calculated. Thirty-two percent had subluxation or dislocation in at least one limb. Conclusions: Age-specific cross-sectional area cut-offs and ratios may facilitate a more nuanced interpretation and diagnostic value when used in conjunction with clinical and electrodiagnosis evaluation of ulnar neuropathy at the elbow.

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 Ultrasound (US) guidance may ensure proper needle placement during electromyography (EMG) when assessing for suitable donor muscles for upper limb reconstruction. A distinct intermuscular fascial border aids in delineating the separation between the brachioradialis (BR) and extensor carpi radialis longus (ECRL) muscles. However, this border may be absent, making correct needle placement complex and assessment more difficult. The purpose of this study was to describe the presence and absence of this fascial border in healthy individuals to help with accurate EMG needle placement. Methods Twenty healthy patients underwent sonographic examination by a single sonographer physician of the ECRL and BR to identify the presence or absence of the intermuscular fascial border. Results The fascial border that routinely separates the ECRL and BR was absent in at least one arm in 20% of subjects (12.5% of upper limbs). One subject had an absent fascial border in both upper limbs. Discussion US can assess for the presence or absence of intermuscular fascial borders. This assessment is important for accurate EMG needle placement and localization. While the clinical significance of an absent ECRL‐BR fascial border is currently unknown, future studies should examine the effect of absent ECRL‐BR fascial borders on wrist extension.

Abstract Introduction/Aims Point‐of‐care ultrasound of the diaphragm is highly sensitive and specific in the detection of neuromuscular diaphragmatic dysfunction. In some patients with neuromuscular diaphragmatic dysfunction, paradoxical thinning of the diaphragm during inspiration is observed on ultrasound; however, its frequency, electrodiagnostic associations, and prognostic significance remain uncertain. Methods Medical records of patients presenting to two electrodiagnostic laboratories (Mayo Clinic, Rochester, Minnesota and University of Alberta, Edmonton, Alberta) from January 1, 2022 to December 31, 2022, for evaluation of suspected neuromuscular respiratory failure, were reviewed. Results 214 patients were referred and 19 patients excluded due to incomplete information. Of 195 patients (384 hemidiaphragms), 104 had phrenic neuropathy, 12 had myopathy, and 79 had no evidence of neuromuscular disease affecting the diaphragm. Paradoxical thinning occurred in 31 (27%) patients with neuromuscular diaphragmatic dysfunction and was unilateral in 30, the majority (83%) having normal contralateral ultrasound. Phrenic nerve conduction studies and diaphragm electromyography results did not distinguish patients with paradoxical thinning versus without. Most patients (71%) with paradoxical thinning required non‐invasive ventilation (NIV), including 16 with unilateral paradoxical thinning. Paradoxical thinning and BMI ≥30 kg/m 2 were risk factors for requiring NIV in multivariable logistic regression analysis, with odds ratios of 2.887 (95% CI:1.166, 7.151) and 2.561 (95% CI: 1.186, 5.532), respectively. Discussion Paradoxical thinning of the diaphragm occurs in patients with prominent neuromuscular diaphragmatic dysfunction, most commonly from phrenic neuropathy, and is a significant risk factor for requiring NIV. Unilateral paradoxical thinning is sufficient for needing NIV. BMI ≥30 kg/m 2 additionally increases risk of requiring NIV in patients with neuromuscular diaphragmatic dysfunction.

The quality of healthcare delivery is dependent on collaboration between various professional disciplines. Integrating opportunities for interprofessional learning in medical education programs will prepare future clinicians to be effective members of a multi‐disciplinary care team. We incorporated an ultrasound demonstration of the upper limb into the gross anatomy courses for first year medical (n=53) and physical therapy (n=28) students. Prior to participating in the learning experience, all students took a short individual pre‐test based on clinical concepts regarding the assigned study material. A physical medicine and rehabilitation physician demonstrated the use of ultrasound as a diagnostic and procedural tool for the shoulder and elbow. Following the demonstration, students worked within interprofessional teams (n=14 teams) to review the related anatomy on dissected specimens. At the end of the session, students worked within interprofessional teams to complete a collaborative post‐test. Team scores were compared to the mean individual score within each team using a paired t‐test. Students scored higher on the collaborative post‐test (5.7/6) than on the individual pre‐test (4.2/6), p <0.0001. Results suggest that working in interprofessional teams may enhance understanding and clinical application of anatomy, thereby reinforcing the benefit of an interdisciplinary team approach to patient care.

ABSTRACT Purpose This study aimed to evaluate the incidence and characteristics of exertional rhabdomyolysis (ER) in a population-based cohort. Methods A retrospective cohort study was performed in Olmsted County, Minnesota, from 2003 to 2015. Incident ER cases were ascertained through the Rochester Epidemiology Project medical record linkage system through electronic searches of the International Classification of Diseases, Ninth Revision , codes and clinical note text. Population incidence rate was calculated using the corresponding Rochester Epidemiology Project census populations specific to calendar year and sex. Descriptive statistics were used. Results Of the 430 patients, 431 cases met the inclusion criteria for rhabdomyolysis; 4.9% of cases ( n = 20; males n = 18; Caucasian n = 17) were ER, with one recurrence. There were no deaths secondary to ER. The age- and sex-adjusted incidence rate of ER was 1.06 ± 0.24 (95% confidence interval = 0.59–1.52) per 100,000 person-years. Endurance activity ( n = 7), manual labor ( n = 5), and weight lifting ( n = 4) were common causes. Complications included kidney injury ( n = 5), mild electrolyte abnormalities ( n = 10), elevated transaminases ( n = 12), and minor electrocardiographic abnormalities ( n = 4). A majority of patients were hospitalized ( n = 16) for a median of 2 d, had mild abnormalities in renal and liver function and electrolytes, and were discharged without sequelae. Conclusion ER in the civilian population occurs at a much lower incidence than the military population. The most common causes were endurance exercise, manual labor, and weight lifting. The majority of cases were treated conservatively with intravenous fluid resuscitation during a brief hospital stay, and all were discharged without sequela. Only one case of recurrence occurred in this cohort, indicating the recurrence rate was low.