Measurement of cross‐sectional area of cervical roots and brachial plexus trunks

Introduction: The aim of this study was to determine normal reference values for cross‐sectional area (CSA) and the correlation between demographic factors and CSA in the cervical roots and brachial plexus trunks using ultrasonography. Methods: Ninety‐five age‐matched healthy individuals were studied. Ultrasonographic tests were performed via nerve tracing from the cervical root to the brachial plexus trunk. The CSA of each nerve was measured in the C5–8 ventral roots and brachial plexus (trunk level). Results: Normal values of each cervical root were: C5, 5.66 ± 1.02 mm²; C6, 8.98 ± 1.65 mm²; C7, 10.43 ± 1.86 mm²; and C8, 10.76 ± 2.02 mm². Values for the brachial plexus were: upper trunk, 16.70 ± 2.88 mm²; middle trunk, 14.01 ± 2.70 mm²; and lower trunk, 13.75 ± 2.57 mm². The side‐to‐side discrepancy was 11.91 ± 11.11%. Body mass index (BMI) and height correlated frequently with nerve CSA. Conclusions: These reference values may be helpful in investigating pathologies involving the cervical area. Muscle Nerve 46: 711–716, 2012     

The effect of magnification on sonographically measured nerve cross‐sectional area

Introduction: The primary aim of this investigation was to determine whether use of write‐zoom magnification affects sonographically determined cross‐sectional area (CSA) of peripheral nerves. Methods: CSAs of the median (MN) and posterior interosseous (PIN) nerves were measured in 22 limbs from 11 asymptomatic volunteers using both standard imaging and write‐zoom magnification. CSA measurements were repeated on the same images 1 week later. Results: The average CSA of write‐zoomed images for the MN was significantly larger at both measurement sessions (week 1: 11.1 mm² write‐zoom vs. 10.0 mm² standard, P = 0.019; week 2: 11.8 mm² vs. 10.4 mm², P = 0.023). Similar differences were noted for the PIN (week 1: 2.3 mm² vs. 1.9 mm², P = 0.002; week 2: 2.5 mm² vs. 1.9 mm², P = 0.001). Conclusions: Write‐zoom magnification may significantly increase the measured CSA of peripheral nerves. These changes appear to be more substantial when smaller nerves are measured. Muscle Nerve 51 : 30–34, 2015     

Effects of unilateral electromyostimulation superimposed on voluntary training on strength and cross‐sectional area

In this study we investigate the effects of unilateral voluntary contraction (VC) and electromyostimulation superimposed on VC (EV) training on maximal voluntary (MVC) force and cross‐sectional area (CSA), as assessed by magnetic resonance imaging of knee extensors. Thirty young men were randomly assigned to either a control group (CG), VC group (VG), or EV group (EVG). The VG and EVG trained the right leg isometrically three sessions per week for 6 weeks. After training, MVC increased in the right leg in the VG and in both legs in the EVG, and EVG was significantly different from CG (all P < 0.01). Increased CSA was found only in the right leg in the VG and EVG (P < 0.01), and correlated with improvements of MVC (r = 0.49, P = 0.01). It appeared that the EV training was equally effective as VC at increasing MVC and CSA, while having a greater cross‐education effect. Increased strength without muscle hypertrophy in the unexercised leg of the EVG indicated that neural adaptation was responsible for the cross‐education effect. Muscle Nerve 40: 430–437, 2009     

Characterization of intraluminal impedance patterns associated with gas reflux in healthy volunteers

Abstract  Multichannel intraluminal impedance (MII) recording allows assessment of flow through the oesophagus and differentiation between liquid and gas contents. Existing MII criteria for recognition of gas gastro-oesophageal reflux (GOR) have not been validated during known gas GOR in humans. Aims: (i) Characterize MII patterns of known gas GOR and optimize criteria. (ii) Clarify interrelationships between magnitude of maximal impedance change, luminal diameter and electrode-mucosa contact. Ten healthy volunteers (six male, 21–37 years) were studied using an oesophageal MII-manometry catheter. After catheter placement, subjects were asked to drink 600 mL of carbonated soft drink. Recordings were made for 20 min and the protocol repeated. Reported belches confirmed manometrically (triggered by transient lower oesophageal sphincter relaxations) were included for analysis. Those episodes were compared against commonly used criteria. Another five subjects (three male, 26–52 years) underwent simultaneous MII and videofluoroscopy using the same protocol. Videofluoroscopic images were analyzed for luminal diameter and the presence of electrode–mucosa contact. All analyzed gas GOR episodes ( n  = 88) were associated with a pattern of impedance rise which was either retrograde (62.5%), synchronous (19.3%) or antegrade (18.2%). Depending on the exact criteria used, sensitivity ranged from 33% to 75%. A multivariate regression model including luminal diameter and the presence of electrode-mucosa contact as independent factors accounted for 53% of all variation in impedance changes. In conclusion, a significant number of gas GOR episodes does not meet criteria for their recognition. New criteria are proposed to include specific antegrade patterns of impedance rise. Luminal diameter and the extent of contact between the oesophageal mucosa and MII-electrodes influence the magnitude and patterning of impedance change.     

Effects of position on oesophageal function: studies using combined manometry and multichannel intraluminal impedance

Multichannel intraluminal impedance (MII) allows assessment of intraoesophageal bolus transit. In the supine position, bolus transit is produced almost exclusively by peristaltic contractions; in the upright position, gravity also contributes to bolus transit. MII and peristaltic pressures were measured in four positions (0, 30, 60 and 90 degrees ) using ten swallows (5 cc each) of both water and viscous liquid with body position determined by random choice. Tracings were analysed for total bolus transit time: time interval between bolus entry at 20 cm above and bolus exit at 5 cm above the lower oesophageal sphincter (LOS) and contraction amplitudes at 5 and 10 cm above the LOS. Statistical comparison of mean values of all four body positions was done using anova and Bonnferoni post-test. Ten normal subjects (five females and five males, age 24-45 years) completed the study. At each body position, liquid material transited faster (P < 0.001) than viscous material. Both liquid and viscous materials transited at lower inclinations (0 and 30 degrees ) significantly slower than at higher inclinations (60 and 90 degrees ). There was an almost perfect inverse linear correlation between angle of inclination and bolus transit time for both liquid (r = -0.99) and viscous (r = -1.00) boluses (Spearman correlation r > 0.99 and P < 0.02 for both substances). Contraction amplitudes for liquid vs viscous material were not significantly different at a given degree of inclination. Mean distal oesophageal amplitude declined with increasing inclination. Combined MII-OM identifies and quantifies the effects of gravity on the dichotomy between specific pressures measured by OM and function assessed as transit measured by MII.     

Reliability of side‐to‐side ultrasound cross‐sectional area measurements of lower extremity nerves in healthy subjects

Introduction: In peripheral nerve ultrasound, the healthy contralateral side may be used as internal control. Therefore, inherent side‐to‐side differences must be minimal. The goal of this study was to assess intrastudy, intraobserver, and interobserver reproducibility of ultrasound in comparative side‐to‐side evaluation of lower limb nerves. Methods: Lower limb nerves of 60 normal subjects were evaluated by 3 radiologists. Bilateral sciatic, tibial, common fibular, sural, lateral femoral cutaneous, femoral, obturator, and saphenous nerves were evaluated. Results: Overall, side‐to‐side differences were not statistically significant at any level. In the lower limb nerves, in a between‐limb comparison, the minimum detectable difference of cross‐sectional area ranged from 16.4 mm² (sciatic nerve at the level of piriformis muscle) to 0.4 mm² (saphenous nerve). Conclusion: In general, the healthy contralateral side can be used as an internal control. Muscle Nerve 46: 717–722, 2012     

Diagnosis of supra‐esophageal gastric reflux: correlation of oropharyngeal pH with esophageal impedance monitoring for gastro‐esophageal reflux

Background Oropharyngeal (OP) pH monitoring has been developed as a new way to diagnose supra‐esophageal gastric reflux (SEGR), but has not been well validated. Our aim was to determine the correlation between OP pH and gastro‐esophageal reflux (GER) events detected by multichannel intraluminal impedance‐pH (MII‐pH). Methods Fifteen patients (11 males, median age 10.8 years) with suspected GER were prospectively evaluated with ambulatory 24‐h OP pH monitoring (positioned at the level of the uvula) and concomitant esophageal MII‐pH monitoring. Potential OP events were identified by the conventional pH threshold of <4 and by the following alternative criteria: (i) relative pH drop >10% from 15‐min baseline and (ii) absolute pH drop below thresholds of <5.5, 5.0, and 4.5. The 2‐min window preceding each OP event was analyzed for correlation with an episode of GER detected by MII‐pH. Key Results A total of 926 GER events were detected by MII‐pH. Application of alternative pH criteria increased the identification of potential OP pH events; however, a higher proportion of OP events had no temporal correlation with GER (45–81%), compared with the conventional definition of pH < 4 (40%). A total of 306 full‐column acid reflux episodes were detected by MII‐pH, of which 10 (3.3%) were also identified by OP pH monitoring. Conclusions & Inferences Use of extended pH criteria increased the detection of potential SEGR events, but the majority of decreases in OP pH were not temporally correlated with GER. Oropharyngeal pH monitoring without concurrent esophageal measurements may overestimate the presence of SEGR in children.     

Physiological cross‐sectional area of the oblique head of the adductor pollicis is greater than its transverse counterpart: Implications for functional testing

Introduction: Despite structural distinction between the transverse and oblique heads of the adductor pollicis, in vivo testing continues to consider the adductor pollicis as functionally simplistic. As a muscle's architecture is a strong indicator of function, in this study we aimed to determine whether the physiological cross‐sectional areas (PCSAs) of both heads were uniform. Methods: Classical, microdissection, and chemical dissection procedures were conducted on 10 cadaveric left hands to determine structural origin and insertions. Architectural measures of muscle length (L_m), muscle weight (W_m), fascicle length (L_f), sarcomere length (L_s), and pennation angle (θ) were used to calculate PCSA and fascicle length:muscle length ratio (L_f:L_m). Results: The oblique head had greater variation in attachments, significantly greater PCSA (P = 0.008), and smaller L_f:L_m (P = 0.001) than its transverse counterpart. Conclusions: Muscle architecture suggests the oblique head has greater potential for force generation, and the transverse has greater potential for joint excursion. Muscle Nerve 49 :405–412, 2014     

Ultrasonographic cross‐sectional area normal values of the ulnar nerve along its course in the arm with electrophysiological correlations in 100 asian subjects

Introduction: Normative cross‐sectional areas (CSAs) have been obtained for the Western population. We obtained CSAs of normal ulnar nerves at predetermined sites and correlate them with electrophysiological variables in Asian subjects. Methods: One hundred healthy volunteers, mean age 39 ± 14 years (range, 18–75 years), were recruited for the study after obtaining informed consent. The ulnar nerve was examined ultrasonographically from wrist to axilla, and CSA was measured at predetermined sites. All subjects underwent a simultaneous standardized nerve conduction study. Results: Men had larger CSAs, and CSAs increased with advancing age. There was a statistically significant correlation between CSA at the wrist and distal ulnar motor latency (P = 0.005). Conclusions: Ulnar CSA correlated with age, gender, and distal motor latency. No correlations were observed with height, weight, or body mass index. Muscle Nerve 47: 673–676, 2013     

Normal values of median nerve cross‐sectional area obtained by ultrasound along its course in the arm with electrophysiological correlations,in 100 Asian subjects

Introduction: The objective of this study is to obtain normative cross‐sectional area (CSA) values for median nerve by ultrasound at predetermined sites and correlate them with electrophysiological variables in healthy Asian subjects. Methods: The median nerve was examined ultrasonographically in 100 healthy volunteers, mean age 39 years (range, 18–75 years). CSA of the median nerve was measured at wrist, mid‐forearm, mid‐arm, and axilla. All subjects underwent simultaneous standardized nerve conduction studies. Results: The mean median nerve CSAs ± SD at the distal wrist crease was 7.2 ± 1 mm²; mid‐forearm 4.8 ± 0.9 mm²; mid‐arm 6.1 ± 1 mm²; axilla 5.9 ± 0.9 mm². The CSA at the wrist was the largest compared with other levels (P < 0.001), and it increased with advancing age (P < 0.002). Conclusions: These normative data show that median nerve CSA is not uniform along its length. There are differences between gender, and values increase with advancing age. Muscle Nerve 49 : 284–286, 2014     

Effect of interval between swallows on oesophageal pressures and bolus movement in normal subjects – Studies with combined multichannel intraluminal impedance and oesophageal manometry

The effect of closely spaced swallows to decrease peristalsis ('deglutitive inhibition') is believed to be due to both central inhibitory impulses and smooth muscle refractoriness. Ten volunteers (three females, age 26-65) were given both four pairs and two series of four swallows at 5-, 10-, 15-s intervals and control swallows at 30-s intervals. Oesophageal function was assessed using combined multichannel intraluminal impedance and oesophageal manometry (MII-OM). Swallows were considered manometrical effective if distal oesophageal pressures >/=30 mmHg. Complete bolus transit was defined as bolus exiting from all three distal impedance segments. During swallowing at 5-s intervals the majority of initial swallows were ineffective with incomplete bolus transit while the last swallow in both series and pairs was manometrically effective with complete bolus transit. During swallowing at 10-15-s intervals the number of manometric ineffective swallows and swallows with incomplete bolus transit progressively increased with the number of swallows. The functional information obtained by MII-OM indicates pooling of liquid in the distal oesophagus that is cleared by the last swallow determined by, previously reported, neural inhibition occurring during swallowing spaced 5 s apart whereas incomplete bolus transit is related to manometrically ineffective swallows resulting from muscle refractoriness occurring during swallowing at 10-15-s intervals.     

Relationship between baseline impedance levels and esophageal mucosal integrity in children with erosive and non-erosive reflux disease

Background Baseline impedance measurement has been reported to be related to esophageal acid exposure and hypothesized to be a marker of microscopic changes of the esophageal mucosa. Aims of the study were to establish whether any relationship existed between the magnitude of intercellular space diameter (ISD) of esophageal mucosa and baseline impedance levels in children with gastro‐esophageal reflux disease (GERD), and to compare baseline impedance levels between children with non erosive (NERD) and erosive (ERD) reflux disease. Methods Fifteen children (median age: 11.2 years) with NERD, and 11 with ERD (median age: 9.6 years) were prospectively studied. All patients underwent upper endoscopy. Biopsies were taken 2–3 cm above the Z‐line, and ISD was measured using transmission electron microscopy. All patients underwent impedance pH‐monitoring, and baseline impedance levels were assessed in the most distal impedance channel. Key Results Mean (±SD) ISD did not differ between NERD (1.0 ± 0.3 μm) and ERD (1.1 ± 0.3 μm, ns). Considering all patients together, no correlation was found between distal baseline impedance and ISD (r: ?0.15; ns). Conversely, negative correlations were found between distal baseline impedance and acid exposure time (r: ?0.76; P < 0.001), long‐lasting reflux episodes (r: ?0.78; P < 0.001), acid reflux episodes (r: ?0.62; P < 0.001), and acid clearance time (r: ?0.79; P < 0.001). Distal baseline impedance was significantly lower in ERD [1455 (947–2338) Ω] than in NERD children [3065 (2253–3771) Ω; P < 0.01]. Conclusions & Inferences In children with GERD baseline impedance levels are not useful in predicting reflux‐induced ultrastructural changes in the esophageal mucosa, despite their ability to discriminate between NERD and ERD.