João Antonio Maciel Nóbrega

The role of membranous urethral afferent autonomic innervation in the continence mechanism after nerve sparing radical prostatectomy: a clinical and prospective study

PURPOSE We evaluated the somatic and autonomic innervation of the pelvic floor and rhabdosphincter before and after nerve sparing radical retropubic prostatectomy using neurophysiological tests and correlated findings with clinical parameters and urinary continence. MATERIALS AND METHODS From February 2003 to October 2005, 46 patients with prostate cancer were enrolled in a controlled, prospective study. Patients were evaluated before and 6 months after nerve sparing radical retropubic prostatectomy using the UCLA-PCI urinary function domain and neurophysiological tests, including somatosensory evoked potential, and the pudendo-urethral, pudendo-anal and urethro-anal reflexes. Clinical parameters and urinary continence were correlated with afferent and efferent innervation of the membranous urethra and pelvic floor. We used strict criteria to define urinary continence as complete dryness with no leakage at all, not requiring any pads or diapers and with a UCLA-PCI score of 500. Patients with a sporadic drop of leakage, requiring up to 1 pad daily, were defined as having occasional urinary leakage. RESULTS Two patients were excluded from study due to urethral stricture postoperatively. We evaluated 44 patients within 6 months after surgery. The pudendo-anal and pudendo-urethral reflexes were unchanged postoperatively (p = 0.93 and 0.09, respectively), demonstrating that afferent and efferent pudendal innervation to this pelvic region was not affected by the surgery. Autonomic afferent denervation of the membranous urethral mucosa was found in 34 patients (77.3%), as demonstrated by a postoperative increase in the urethro-anal reflex sensory threshold and urethro-anal reflex latency (p <0.001 and 0.0007, respectively). Six of the 44 patients used pads. One patient with more severe leakage required 3 pads daily and 23 showed urinary leakage, including 5 who needed 1 pad per day and 18 who did not wear pads. Afferent autonomic denervation at the membranous urethral mucosa was found in 91.7% of patients with urinary leakage. Of 10 patients with preserved urethro-anal reflex latency 80% were continent. CONCLUSIONS Sensory and motor pudendal innervation to this specific pelvic region did not change after nerve sparing radical retropubic prostatectomy. Significant autonomic afferent denervation of the membranous urethral mucosa was present in most patients postoperatively. Impaired membranous urethral sensitivity seemed to be associated with urinary incontinence, particularly in patients with occasional urinary leakage. Damage to the afferent autonomic innervation may have a role in the continence mechanism after nerve sparing radical retropubic prostatectomy.

Quantitative analysis of EEG background activity in patients with rolandic spikes

OBJECTIVE The aim was to compare the background activity, through quantitative EEG analysis, of patients with rolandic spikes and normal age-matched controls. MATERIAL AND METHODS Twenty-one channel EEG of 23 children with rolandic spikes and 39 normal children, with ages ranging from 7 to 12 years, were submitted to quantitative analysis (FFT) of discharge-free epochs. Patients and controls were divided in groups according to age (7-9 and 10-12 years old). Delta, theta, alpha and beta frequency ranges were compared between groups for all electrode positions. RESULTS Comparing normals, the 7-9 years old group showed power reduction in the alpha and beta ranges. Comparing patients and normal age-matched groups, the patients showed power increase, at all frequency ranges in the 7-9 years old group and at delta and theta frequency ranges in the 10-12 years old group. CONCLUSIONS Our findings agree with recent evidences that these children may differ from normal (besides the eventual occurrence of seizures); but they also suggest that these differences can be related to immaturity and not necessarily related to the epileptiform discharge.

A brief historical note on the classification of nerve fibers

This is a brief review of the literature focused on the articles that formed the basis for the classification of the nerve fibers. Mention is also made to the origin of the nomenclature of the different motoneurons (alpha, beta and gamma).

Reproducibility in nerve conduction studies and F-wave analysis

OBJECTIVE Reproducibility testing of nerve conduction studies and F-wave latencies in a group of healthy volunteers. METHODS A total of 32 healthy volunteers underwent sensory and motor nerve conduction studies of the ulnar and tibial nerves, including F-waves, elicited by 32 stimuli, repeated in two different days by the same examiner. RESULTS The F-wave latencies showed less variability than the other parameters of conduction studies, and, among them, the F-wave mean latency of the tibial nerve has been the one with the higher reproducibility. CONCLUSIONS F-wave latencies were the parameters with best reproducibility, followed by conduction velocities and amplitudes. SIGNIFICANCE Our data showed that the F-wave mean latency is a parameter with a high reliability, considering the reproducibility, for sequential studies.

A comparison between different parameters in F-wave studies

Ulnar nerve F-waves were studied in 23 healthy volunteers and 27 diabetic patients. Latencies and chronodispersion were analyzed in each group. In the diabetic group all the parameters were normal in 14 patients (52%) and in 13 (48%) at least one parameter was altered. In these patients the most frequently altered parameter was the maximum latency (92%), followed by mean latency (85%), minimum latency (54%) and chronodispersion (54%). These findings suggest that maximum and mean latencies are better parameters to be analyzed in ulnar F-wave studies than minimum latency.

Paralisia do músculo cricoaritenóideo lateral: relato de caso como contribuição ao estudo da anatomia funcional da laringe

In the last few years electromyography of the larynx (EMG) has become helpful in the evaluation of vocal fold immobility, especially to differentiate paralysis from fixation, and providing data for diagnosis, site of lesion and prognosis. Based on a case of selective paralysis of lateral cricoarytenoid muscle in a woman who had paralyzed vocal fold at lateral position, confirmed by electromyography study, we conducted an analysis in order to understand the role of intrinsic laryngeal muscles.

Sample size and the study of F waves

Ulnar nerve F waves were studied in 23 healthy volunteers and 27 diabetic patients. Latencies and chronodispersion were analyzed in each group for different sample sizes. Significant differences were not detected with the different sample sizes for mean latencies, with samples above 16 stimuli or 10 waves for minimum and maximum latencies and above 20 stimuli or 16 waves for chronodispersion.These findings suggest that these limits may be adequate for group comparison. However, for the analysis of individual patients, the evidence suggests that larger samples are required for the determination of the minimum and maximum latencies and chronodispersion.

Normative data of F-wave measures in China

OBJECTIVE To establish normal ranges of F-wave measures in China as compared to published data in Brazil and Japan. METHOD We studied F waves in 127 healthy Chinese subjects, aged 21-78 years old, stimulating the median, ulnar, tibial and peroneal nerves distally and proximaly. RESULT The F-wave latencies had a linear correlation to the subject height in all nerves tested, showing a steeper (P < 0.05) regression line in Brazil compared to China and Japan for the tibial nerve. The Chinese population also had a higher distally elicited F-wave persistence and faster F wave conduction velocities than previously reported for both ulnar and tibial nerves. These values showed significant difference (P < 0.05) compared to Brazil but not to Japan. CONCLUSION F-wave latencies show a linear correlation to subject height, although the slope of regression lines varies among countries, reflecting the difference in F-wave persistence and F-wave conduction velocity. SIGNIFICANCE Our study provides a rational for the use of a latency-height nomogram in clinical studies and underscores the importance of developing country specific normative data.

Determinação do limiar de percepção de corrente elétrica em uma amostra de voluntários normais

Reference values using the instrument Neurometer® were determined and compared with those suggested by the manufacturer; the sensory thresholds for the different frequencies in different body segments were determined; the influence of age, level of education, gender and the reutilization of the electrodes in the different sites were also evaluated. Sensory threshold was determined in 101 normal volunteers (68 women), ages ranged from 17 to 87 years old. The procedure was fully automated with the sensory threshold being determined by the method of limits followed by the forced choice method. Analysis of the results revealed that: there was a significant difference between the values obtained for the index fingers and the halux; no difference was detected between both index fingers; gender and level of instruction had no effect on the results, age had a small influence after stimulation with 2000Hz and 250Hz; three reutilizations of the electrodes did not affect the results on the index fingers, however at the halux, the third utilization deteriorated the results from the 2000Hz stimulation. Except for the 2000Hz stimulation, significant differences were suggested between the values reported here and those provided by the manufacturer.

Pudendal somatosensory evoked potentials in normal women

OBJECTIVE Somatosensory evoked potential (SSEP) is an electrophysiological test used to evaluate sensory innervations in peripheral and central neuropathies. Pudendal SSEP has been studied in dysfunctions related to the lower urinary tract and pelvic floor. Although some authors have already described technical details pertaining to the method, the standardization and the influence of physiological variables in normative values have not yet been established, especially for women. The aim of the study was to describe normal values of the pudendal SSEP and to compare technical details with those described by other authors. MATERIALS AND METHODS The clitoral sensory threshold and pudendal SSEP latency was accomplished in 38 normal volunteers. The results obtained from stimulation performed on each side of the clitoris were compared to ages, body mass index (BMI) and number of pregnancies. RESULTS The values of clitoral sensory threshold and P1 latency with clitoral left stimulation were respectively, 3.64 +/- 1.01 mA and 37.68 +/- 2.60 ms. Results obtained with clitoral right stimulation were 3.84 +/- 1.53 mA and 37.42 +/- 3.12 ms, respectively. There were no correlations between clitoral sensory threshold and P1 latency with age, BMI or height of the volunteers. A significant difference was found in P1 latency between nulliparous women and volunteers who had been previously submitted to cesarean section. CONCLUSIONS The SSEP latency represents an accessible and reproducible method to investigate the afferent pathways from the genitourinary tract. These results could be used as normative values in studies involving genitourinary neuropathies in order to better clarify voiding and sexual dysfunctions in females.