Nerve In Volunteers Research Articles

Ferumoxytol-enhanced vascular suppression in magnetic resonance neurography.

To evaluate ferumoxytol-enhanced vascular suppression for visualizing branch nerves of the brachial plexus in magnetic resonance (MR) neurography. Signal simulations were performed to determine ferumoxytol's effect on nerve-, fat-, and blood-to-muscle contrast and to optimize pulse sequence parameters. Prospective, in vivo assessment included 10 subjects with chronic anemia who underwent a total of 19 (9 bilateral) pre- and post-infusion brachial plexus exams using three-dimensional (3D), T2-weighted short-tau inversion recovery (T2-STIR) sequences at 3.0T. Two musculoskeletal radiologists qualitatively rated sequences for the degree of vascular suppression and brachial plexus branch nerve conspicuity. Nerve-to-muscle, -fat, and -vessel contrast ratios were measured. Quantitative nerve/muscle and nerve/small vessel contrast ratios (CRs) increased with ferumoxytol (p < 0.05). Qualitative vascular suppression and suprascapular nerve visualization improved following ferumoxytol administration for both raters (p < .05). Pre- and post-ferumoxytol exams demonstrated moderate to near-perfect inter-rater agreement for nerve visualization and diagnostic confidence for the suprascapular and axillary nerves but poor to no agreement for the long thoracic nerve. Ferumoxytol in T2-weighted brachial plexus MR neurography provides robust vascular suppression and aids visualization of the suprascapular nerve in volunteers without neuropathy.

Influence of Leg Position on the Depth and Sonographic Appearance of the Sciatic Nerve in Volunteers

We investigated the effect of leg position on the depth of the sciatic nerve and quality of ultrasound images taken at the proximal and mid-thigh level. Twenty-one volunteers with average body mass index were recruited to represent the younger population receiving sciatic nerve blocks for sports injury surgery. The volunteers were placed in the lateral position, with the hip flexed and with the hip in a neutral (extended) position. A single operator imaged the uppermost leg and the best images of the sciatic nerve at the proximal and mid-thigh level were saved. Sciatic nerve depth was measured at each level. Eleven clinicians experienced in ultrasound-guided regional anaesthesia assessed the paired images. In the proximal thigh, the sciatic nerve depth was greater with the hip flexed compared to the neutral position (median 30 vs 23 mm, P = 0.0002). There was no consistent difference in the mid-thigh. More clinicians favoured the proximal sciatic image with the leg in the neutral position. Although statistically significant, the depth difference is probably not a major clinical consideration in most patients with an average body mass index. We suggest clinicians place the leg in the most ergonomically favourable position when performing sciatic nerve blocks in the proximal thigh in these patients.

Sensory Phenomena in Experimental Nerve Block

In the course of a series of blocks of the ulnar and lateral popliteal nerves of volunteers a study was made of the manner in which the responses of the subject to sensory stimulation become progressively altered and finally obliterated. These changes are described, together with the manner of recovery, and an account is given of various sensations induced by the blocking and the recovery processes. The relevant literature is briefly reviewed and possible factors involved in these phenomena are discussed.