Morphological distinction of cervical nerve roots associated with motor function in 219 healthy volunteers: a multicenter prospective study.

STUDY DESIGN: A prospective study. OBJECTIVE: To examine the diameter (mm), transverse diameter (mm), and cross-sectional area (mm²) of the C5, C6, and C7 nerve roots using ultrasonography. SUMMARY OF BACKGROUND DATA: Each of the cervical nerve roots affected a different motor or sensory area. Although there were several studies that performed a detailed assessment of cervical nerve root anatomy in cadavers, only a few studies on the thickness of cervical nerve roots in living specimens have been performed. We examined whether the thickness of the C5, C6, and C7 nerve roots, as well as the area supplied by each of the roots, varied. METHODS: All 219 subjects (99 males and 120 females; mean age, 47 ± 15 yr) were healthy volunteers. The diameter and the transverse diameter were measured via ultrasonography, and the cross-sectional area was calculated for each of the C5-C7 nerve roots. RESULTS: The following diameter measurements (right and left, respectively) were obtained: C5, 2.8 and 2.9 mm; C6, 3.6 and 3.8 mm; and C7, 3.3 and 3.4 mm. The following transverse diameter measurements were obtained (right and left, respectively): C5, 2.8 and 3.0 mm; C6, 3.7 and 3.8 mm; and C7, 3.5 and 3.4 mm. The following cross-sectional area measurements (right and left, respectively) were obtained: C5, 6.3 and 6.4 mm²; C6, 10.7 and 11.0 mm²; and C7, 8.8 and 8.8 mm². Based on the 3 measurement methods, the C5 nerve root was significantly thinner than the other 2 nerve roots (P < 0.001), and the C7 nerve root was smaller than the C6 nerve root (P = 0.001). CONCLUSION: The C5 nerve root was significantly thinner than the C6 and C7 cervical nerve roots. The fact that the C5 nerve is thinner may render it more susceptible to damage during cervical surgery.

A simple, 10-minute procedure for transforaminal injection under ultrasonic guidance to effect cervical selective nerve root block.

The aim is to provide a detailed procedure of a simple and 10-minute cervical nerve root block (CNRB) under ultrasonic guidance, and to report the clinical outcomes, disorders, and complications. Records of patients who had undergone CNRB, were reviewed under ultrasonic guidance at the hospital from 2010 through 2012. The procedure is described in detail. Arm and shoulder pain was evaluated by use of the visual analogue scale (VAS). Forty-three patients agreed to undergo CNRB under ultrasonic guidance. Nerve roots from C5 to C8 were affected in 41, and these nerve roots were readily distinguished. Two of the 43 participants did not receive injections because impediments in visualizing the affected nerve root. Of the 41 who received injections, radicular pain immediately disappeared in 39, who continued to feel pain relief 1 month later. However, pain recurred in 15 patients (38%), of whom 11 underwent cervical spine surgery. The rest of 24 patients felt sustained pain relief longer than 3 months after the injection, significantly. Although one patient had recurrent radicular pain 10 months later, the pain could be controlled by medication. At the final follow-up periods, 17.2 (10-24 months), the median VAS score of the patients, 23 (0 to 71 mm), was significantly improvement (P = 0.001) in comparison to before injection 88 (range; 56-100). No complications occurred. The cervical nerve root block under ultrasonic guidance simply, safely, and efficaciously decreased radicular pain for 17.2 months in 62% patients with intolerable radicular pain.

Prognostic significance of circadian variability of RR and QT intervals and QT dynamicity in patients with chronic heart failure.

BACKGROUND: In patients with chronic heart failure (CHF), circadian variability of RR and QT intervals may be altered because of neurohumoral activation and functional and structural remodeling of the heart. OBJECTIVE: The aim of this study was to evaluate the prognostic significance of circadian variability of the RR and QT intervals and QT dynamicity (QT/RR slope) in CHF patients. METHODS: We prospectively enrolled 121 patients with stable CHF in sinus rhythm (age 67 +/- 14 years, mean +/- SD; range 34 to 87 years). The RR, QT, and rate-corrected QT (QTc) intervals and the QT/RR slope measured from 24-hour Holter electrocardiogram were fitted by cosine curves. RESULTS: During the follow-up period of 34 +/- 17 months, 40 (33%) patients died of cardiac causes, 10 of which were sudden. All patients showed significant circadian rhythms in the RR, QT, and QTc intervals and the QT/RR slope by cosine-curve fitting. In addition to the expected higher heart rate, longer QT interval, and steeper QT/RR slope, we found that patient who died of cardiac causes had reduced circadian variability of QT interval (10 +/- 10 ms vs 21 +/- 13 ms) and a later maximum RR interval (4.1 +/- 0.9 AM vs 2.3 +/- 2.1 AM) compared with survivors, among many other statistically significant circadian parameter differences. These 2 parameters were independent predictors of cardiac death in multivariate Cox proportional hazards regression analysis. CONCLUSION: Circadian variability analyses of Holter-derived RR and QT intervals may provide prognostic information beyond that provided by 24-hour averages of these parameters.

Prevention of ventricular extrasystole by mexiletine in patients with normal QT intervals is associated with a reduction of transmural dispersion of repolarization.

BACKGROUND: Antiarrhythmic potential of mexiletine in patients with congenital and acquired long-QT syndrome (LQTS) has been attributed to a reduction of transmural dispersion of repolarization (TDR). A similar mechanism could be involved in the antiarrhythmic activity of the drug in patients with normal QT intervals, but the issue remains to be investigated. METHODS AND RESULTS: We analyzed 24-h Holter ECG recordings from 17 patients in sinus rhythm showing premature ventricular complexes (PVCs) with normal QT intervals (age, 62+/-10 years, mean+/-S.D.). Treatment of the patients with oral mexiletine (300 mg/day for 21-40 days) resulted in a significant reduction of PVCs (from 13899+/-18887 to 6949+/-12822 beats/24 h, p<0.01). Rate-dependent behavior of ventricular repolarization was analyzed by plotting QT intervals (QT(peak), QT(end)), and the interval from T-wave peak to T-wave end (TPE) against preceding respective RR intervals of sinus beats. Both the QT(peak) and QT(end) tended to be shortened by mexiletine at RR intervals from 600 ms to 1000 ms, although the changes did not reach statistical significances. TPE, which reflects TDR, was shortened significantly at relatively long RR intervals (by 14+/-9% at RR of 900 ms, p<0.05). There was a linear relationship between the percentage shortening of TPE and the percentage reduction of PVCs (r=0.86, p<0.04). TPE> or =70 ms was significantly associated with PVC suppression >75% with an odds ratio of 0.60 (95% confidence interval 0.36-0.98, per 1 ms increment). CONCLUSION: Inhibitory effect of mexiletine against PVCs in patients with normal QT intervals is mediated at least in part by a reduction of TDR. Mexiletine may be effective in patients exhibiting longer baseline TPE.