Meiling, James B.

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.

ABSTRACT Introduction/Aims Accurate needle electromyography (EMG) of the short head of the biceps femoris (SHBF) is often important to localize nerve damage when proximal to the fibular head. Techniques have been proposed for accurate SHBF EMG; however, needle placement accuracy is low and with the risk of inadvertent needle placement into the long head (LHBF) potentially resulting in false localization and inappropriate operative management. This study aimed to define the optimal window for accurate SHBF needle EMG placement through ultrasound (US) investigation of the anatomical relationships of the SHBF, LHBF, and common fibular nerve (CFN) in the distal posterolateral thigh. Methods Forty lower limbs from 20 healthy adults were evaluated using US. Distances from the popliteal crease (PC) to the SHBF and LHBF myotendinous junctions and position of the CFN in the popliteal fossa were recorded. The “SHBF window” was defined as the region where the SHBF muscle body is present in the absence of the LHBF. Results The SHBF was located anterolateral to the LHBF tendon/muscle and the CFN medial to the SHBF in all limbs. The average distances from the PC to SHBF and LHBF muscles were 0.6 and 6.4 cm, respectively. The optimal “SHBF window” was identified to be 3–4 cm (2–3 fingerbreadths) proximal to the PC, anterolateral to the LHBF tendon in the distal thigh. Discussion SHBF examination within this optimized window results in increased accuracy of needle placement, aiding in the electrodiagnostic localization of fibular nerve lesions.

ABSTRACT Introduction/Aims Scapular winging occurs as an abnormal protrusion of the scapula due to nerve injury, muscle weakness, bone, or joint pathology. The main muscular stabilizers of the scapula include the serratus anterior, trapezius, rhomboid major and minor, levator scapulae, and pectoralis minor. Needle electromyography (EMG) has historically been used as one of the primary diagnostic tests for evaluating this finding. However, sampling of these muscles can be technically difficult and carries risks for complications. Muscle ultrasound (MUS) can also reliably identify abnormalities in the muscles involved in scapular stabilization while offering the benefit of rapid side‐to‐side comparison and improved patient comfort. This study aims to highlight the concordance of ultrasound and EMG findings using our published MUS protocol in patients with scapular winging. Methods A retrospective analysis was performed of 13 patients who presented to an electrodiagnostic (EDX) laboratory with the referral diagnosis of “scapular winging” or “scapular dyskinesis.” All patients underwent MUS testing of scapular muscles according to a previously published protocol followed by EMG of muscles deemed relevant by the clinician. Results Seven patients were found to have a neurogenic cause of their scapular winging and in those patients, all had both EMG and MUS abnormalities. MUS was found to have a sensitivity of 87.5%, specificity of 95.7%, and individual muscle concordance with EMG of 90.6%. Discussion There is high concordance between EMG and MUS in patients with scapular winging. This combined with potential advantages of the MUS modality supports their concurrent use in patients with scapular winging.

ABSTRACT Scapular winging (SW) describes abnormal scapular mechanics from weak stabilizing muscles or altered neural innervation. While electromyography (EMG) helps differentiate between myo‐ or neuropathic SW etiologies and determine the extent of muscle involvement, pediatric EMG may be limited due to the high risk of surrounding structures, small body habitus, and pain tolerance. Herein is a case of pediatric SW following anterior neck lymphadenopathy resection in which EMG was limited. Neuromuscular ultrasound (NMUS) showed asymmetric trapezius thinning and hyperechogenicity, revealing more expansive involvement than was previously known. NMUS is a painless, validated tool to augment the diagnostic capability of EMG and clarify the extent of neuromuscular involvement in SW from both a prognostic and rehabilitation point of view.

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 Iatrogenic spinal accessory nerve (SAN) injuries can occur as complications of posterior triangle of the neck surgery, resulting in lateral scapular winging and a shoulder droop. Rarely has this complication been described after a cosmetic rhytidectomy (face‐lift procedure). Here, we present two cases of iatrogenic SAN injuries that occurred after cosmetic rhytidectomies. The use of electrodiagnostic and ultrasound examinations provides invaluable information to assess peripheral nerve injuries. Electrodiagnostic testing can confirm the presence and severity of the injury, while ultrasound can provide additional anatomical information and direct visualization to confirm the continuity of the nerve and assess muscle denervation changes.

ABSTRACTIntroduction/AimsPacinian corpuscles are end organs of the sensory nervous system. The size and superficial location of Pacinian corpuscles allows them to be visualized with high‐resolution ultrasound. This pilot study sought to assess the reliability of Pacinian corpuscle counting in the hand using ultrasound.MethodsTwo healthy participants underwent ultrasound evaluation by three ultrasonographers using a scanning protocol developed for this study. The ultrasound protocol used anatomic landmarks to identify and trace digital nerves in the palms and the adjacent Pacinian corpuscles. The ultrasonographers used morphologic features to identify and count Pacinian corpuscles at two sites in each hand for each participant using a 10–22 MHz linear‐array transducer. The procedure was repeated at 2 time points. Inter‐rater and intrarater reliabilities were determined using intraclass correlation coefficients (ICCs).ResultsPacinian corpuscles were identified in the second–third and fourth–fifth intermetacarpal spaces. The ultrasound appearance of Pacinian corpuscles is of a hypoechoic, rounded structure without a hyperechoic rim. A clustered appearance and septate internal structure are distinct features of Pacinian corpuscles, but these features are not always present. The mean number at each site was between 10.71 and 11.71. Inter‐rater and intrarater reliability both resulted in ICC values over 0.8, indicating “good” inter‐rater and intrarater reliabilities.DiscussionPacinian corpuscles can be reliably counted in the hand using high‐resolution ultrasound. The reliability data from this pilot study may facilitate further ultrasound studies of Pacinian corpuscles, which may be decreased in number or undergo other changes in polyneuropathies.