Background and Purpose Diagnosing ulnar neuropathy at the wrist (UNW) is often challenging, and performing several short segmental studies have been suggested for achieving this. We aimed to determine the utility of ulnar nerve segmental studies at the wrist (UNSWs) in patients with suspected UNW. Methods Fourteen patients with typical symptoms of unilateral UNW were evaluated using conventional electrophysiological tests, UNSWs, and ultrasonography (US). In UNSWs, the ulnar nerve was stimulated at three sites (3 cm distal, just lateral, and 2 cm proximal to the pisiform), and recordings were made at the first dorsal interosseous (FDI) muscle and the fifth digit. Four types of UNW were identified by conventional ulnar nerve conduction studies based on motor and sensory fiber involvement. UNW was also categorized as either a proximal or distal lesion relative to the pisiform based on the UNSWs. The relationships between the conventional electrophysiological type, UNSW categorization results, and lesion location as verified by US were analyzed. Results Proximal UNW lesions were associated with involvement of the entire deep motor and the superficial sensory fibers (type I). Distal lesions were more closely related to deep motor fibers that innervated the FDI (type III). All five proximal and six distal lesions seen in US matched the lesion locations found on UNSWs. Conclusions Motor and sensory UNSW are considered useful assistive techniques for diagnosing UNW and localizing its lesion sites.

Background and Purpose Investigating the supinator muscle (SUP) is important for diagnosing radial neuropathy or cervical radiculopathy in needle electromyography (EMG). However, different authors have proposed several locations for needle EMG placement in the SUP. This study aimed to determine the optimal needle insertion position for examining the SUP via needle EMG under ultrasonographic guidance. Methods This study included 16 male (32 upper limbs) and 15 females (30 upper limbs). In the supine position, the line connecting the midpoint of the dorsal wrist to the upper margin of the radial head (RH) (RH_WRIST line) was measured while the forearm was pronated. Under ultrasonographic guidance, the thickness of the SUP was measured at 1-cm intervals from the RH to 4 cm along the RH_WRIST line. Moreover, the horizontal distance (HD) from the RH_WRIST line to the posterior interosseous nerve (PIN) and the distance from the RH to the point where the RH_WRIST line and the PIN intersected (VD_PIN_CROSS) were measured. Results VD_PIN_CROSS was 51.25±7.0 mm (mean±SD). The muscle was the thickest at 3 cm (5.6±0.8 mm) and 4 cm (5.4±1.0 mm) from the RH. The distances from the PIN to these points were 14.1±3.9 mm and 9.0±4.3 mm, respectively. Conclusions Our findings suggest that the optimal needle placement is at 3 cm from the RH.

In this report, we present the case of a patient with cervical adenocarcinoma with progressive right lower-extremity pain and weakness. Electromyography of the lower extremities and subsequent ultrasonographic imaging complementarily demonstrated findings considered suspicious for the perineural spread of malignancy to the lumbosacral plexus and sciatic nerve. This possibility was confirmed by magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) scanning. This case report suggests that in addition to MRI and FDG PET/CT scans, electromyography and ultrasonographic imaging are valuable modalities for the diagnosis of perineural malignancy.

Electromyographic needle access to the flexor pollicis longus (FPL) is challenging because of the risk of injuries to the superficial radial nerve (SRN) or radial artery (RA), which run close to the FPL. This study aimed to investigate the safe electromyographic needle insertion point of the FPL using a newly proposed RA pulse palpation method. Fifty forearms of 25 healthy individuals were studied. At the junction of the middle and distal third of the forearm, an RA pulse was palpated, and 5 mm lateral to the pulse was determined as the preliminary needle insertion point. The distance from the vertical virtual needle pathway to the RA and SRN was measured using ultrasonography. In ultrasonography, the distances from the needle pathway to the RA and the SRN were 3.4 ± 0.8 (range, 2.1–6.0) and 5.9 ± 1.8 (range, 2.4–9.4) mm, respectively. The depth of the FPL muscle was 8.4 ± 1.7 mm. Electromyographic needle insertion into the FPL can be safely performed using the RA palpation method. The needle insertion point is 5 mm lateral to the RA pulse at the level between the middle and distal third of the forearm.