Objective: To characterize the ultrasonographic findings on nerves in neuralgic amyotrophy.Methods: Fourteen patients with neuralgic amyotrophy were examined using high resolution ultrasound.Results: Four types of abnormalities were found: 1. Focal or diffuse nerve / fascicle enlargement (57%), 2. incomplete nerve constriction (36%), 3. complete nerve constriction with torsion (50%) (hourglass-like appearance), and 4. fascicular entwinement (28%). Torsions were confirmed intraoperatively and occurred on the radial nerve in 85% of the patients. A significant correlation was found between no spontaneous recovery of nerve function and constriction / torsion / fascicular entwinement (p=0.007). Conclusion:Ultrasonographic nerve pathology in neuralgic amyotrophy varies in order of severity from nerve enlargement to constriction to nerve torsion, with treatment moving from conservative to surgical. We postulate that the constriction caused by inflammation is the precursor of torsion and that the development of nerve torsion is facilitated by rotational movements of limbs.

Ultrasonography may be used as a diagnostic aid in neuralgic amyotrophy, which was hitherto a clinical and electrophysiological diagnosis, and may also help in identifying potential surgical candidates. Muscle Nerve 56: 1054-1062, 2017.

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The neurons of the transient subplate zone, considered important for the prenatal development of the cerebral cortex, were shown here to express kynurenine aminotransferase (KAT)-I from embryonic day (E) 16 until postnatal day (P) 7 in the rat. No other cells of brain tissue exerted KAT-I immunoreactivity during this period. From P3 on, the neurons of the subplate gave rise to KAT-I immunoreactive, varicose axons, which entered the thalamus and terminated around thalamic nerve cells that are devoid of KAT-I immunoreactivity. Other subplate markers displayed a different expression pattern during development. Thus, subplate neurons displayed parvalbumin (PV) immuno-reactivity from E16 to P10 and an intense NPY immunoreaction from P7 to P1. They also exhibited nitric oxide synthase immunoreactivity from E16 to P10, whereas on the surface of the subplate neurons, the alpha7 subunit of the nicotinic acetylcholine receptor (nAChR) was present from P1 to P10. The cells of Cajal-Retzius were nAChR-immunoreactive during this period. Between P1 and P7, the perikarya of subplate neurons also showed an intense immuno-reaction with the N-methyl-D-aspartate (NMDA) receptor subtype R2A. After the first postnatal week, many of the KAT-I positive subplate neurons display a gradual decrease of immunoreactivity and undergo programmed cell death. Since KAT-I persists in the subplate through the period E16-P7, we conclude that KAT-I is a useful and reliable subplate marker in the rat. Since it is assumed that migration of nerve cells is regulated by NMDA receptors, and since kynurenic acid--the only naturally occurring NMDA receptor antagonist--is synthesized by KAT, we suggest that a temporary breakdown of the delicate equilibrium between NMDA and KAT might induce abnormal neuronal migration, giving rise to developmental abnormalities.