What is the place of electroneuromyographic studies in the diagnosis and management of pudendal neuralgia related to entrapment syndrome?

Entrapment of the pudendal nerve may be at the origin of chronic perineal pain. This syndrome must be diagnosed because this can result in the indication of surgical decompression of the entrapped nerve for pain relief. Electroneuromyographic (ENMG) investigation is often performed in this context, based on needle electromyography and the study of sacral reflex and pudendal nerve motor latencies. The limits of ENMG investigation, owing to various pathophysiological and technical considerations, should be known. The employed techniques do not assess directly the pathophysiological mechanisms of pain but rather correlate to structural alterations of the pudendal nerve (demyelination or axonal loss). In addition, only direct or reflex motor innervation is investigated, whereas sensory nerve conduction studies should be more sensitive to detect nerve compression. Finally, ENMG cannot differentiate entrapment from other causes of pudendal nerve lesion (stretch induced by surgical procedures, obstetrical damage, chronic constipation...). Thus, perineal ENMG has a limited sensitivity and specificity in the diagnosis of pudendal nerve entrapment syndrome and does not give direct information about pain mechanisms. Pudendal neuralgia related to nerve entrapment is mainly suspected on specific clinical features and perineal ENMG examination provides additional, but no definitive clues, for the diagnosis or the localization of the site of compression. In fact, the main value of ENMG is to assess objectively pudendal motor innervation when a surgical decompression is considered. Perineal ENMG might predict the outcome of surgery but is of no value for intraoperative monitoring.     

Maternal immunity to insulin does not affect diabetes risk in progeny of non obese diabetic mice

It has been suggested that maternal environment, in particular maternal autoantibodies, modify the risk of developing autoimmune diabetes in offspring. The aim of this study was to determine whether modification of maternal environment and maternal diabetes risk through immunization affects autoimmune diabetes risk in the progeny. The risk of developing insulin antibodies and of developing diabetes was determined in 113 female progeny of non obese diabetic (NOD) dams that were immunized with insulin, control antigen or vehicle before or during pregnancy. Although NOD dams immunized with insulin were rendered diabetes resistant (40% diabetes by age 36 weeks versus 100% in control dams), diabetes development in their female offspring (72%, 26/36) was similar to that in female offspring of dams immunized with glucagon (82%, 22/27) or vehicle (76%, 19/25). Furthermore, no significant differences in diabetes development or insulin autoantibody titres were observed between female progeny of insulin autoantibody positive NOD dams (82% diabetes by age 36 weeks, 18/22), insulin autoantibody negative NOD dams (75%, 41/55), and NOD dams that had antibodies against exogneous insulin (71%, 22/31). The findings suggest that modification of the maternal risk for autoimmune diabetes via antigen-specific immunization is not transferred to progeny and that fetal exposure to insulin autoantibodies does not increase the risk for diabetes development.     

Surgical management of primary hyperparathyroidism: the case for giving up quick intraoperative PTH assay in favor of routine PTH measurement the morning after

OBJECTIVE: To analyze the utility of quick intraoperative parathyroid hormone (PTH) measurement in the surgical management of primary hyperparathyroidism. BACKGROUND DATA: The use of intraoperative PTH monitoring is well established in the surgery of primary hyperparathyroidism. However, some false-negative predictions lead to unnecessary explorations; furthermore, surgeons are becoming increasingly dependent on hormone measurement for intraoperative decisions, which raises concerns about the cost-effectiveness of the method. METHODS: A retrospective analysis of 268 neck explorations performed for primary hyperparathyroidism using intraoperative PTH monitoring from April 2001 to February 2003 was done. We used the criterion of "biologic recovery" of hyperfunctioning tissue, defined as a more than 50% decrease in PTH level from baseline value at 5 minutes after excision to predict the outcome of successful parathyroidectomy documented by normal postoperative serum calcium level. Additionally, we also sampled PTH at 10 minutes, 30 minutes, and the morning after surgery to compare the predictive value of delayed sampling. Patients were classified according to the prediction being concordant or discordant with the outcome. The data were analyzed using a 2 x 2 table construct for each of the sampling times, therefore providing sequential sensitivity, specificity, positive and negative predictive values, and overall accuracy of the predictions. RESULTS: Concordance or overall accuracy of prediction (true positives and negatives) was obtained in 229 cases (85.4%), and discordance or failure of prediction (false positives and negatives) was obtained in 34 cases (12.7%) at T5. On analyzing the iPTH prediction at T10, T30, and D1 among the group of 33 false negatives, we found that 28 (10.4%) patients reached the concordance at 30 minutes, while by the first day 32 patients (12.3%) had achieved concordance. Thus, there was a progressive increase in sensitivity and overall accuracy, but more importantly, in the negative predictive value reaching 88.9% on the day after surgery. CONCLUSIONS: The method of sampling PTH intraoperatively at 5 minutes has a high positive predictive value (99.5%) but a low negative predictive value (19.5%), which can lead to unnecessary explorations and a delay in the operative procedure. The negative predictive value increases substantially at 30 minutes and is best on the day after surgery. We suggest giving up the intraoperative measurement of PTH to adopt the first day postoperative measurement of PTH as a predictor of successful parathyroidectomy.     

Quelle est la place de l’examen électroneuromyographique dans le diagnostic des névralgies pudendales liées à un syndrome canalaire?

Severe, chronic perineal pain can result from pudendal nerve entrapment syndrome. This syndrome must be specifically diagnosed because subsequent surgical decompression may provide a significant pain relief. Electroneuromyographic (ENMG) investigation is often performed as a diagnostic measure, based on needle electromyography and the examination of the sacral reflex and pudendal nerve motor latencies. The limits of ENMG methods, owing to various pathophysiological and technical considerations, must be clear. The techniques used do not assess the functional abnormalities at the origin of pain, but rather correlate to structural alterations of the pudendal nerve (demyelination and axonal loss). In addition, only direct or reflex motor innervation is investigated, whereas the specific measurement of sensory nerve conduction would be a more sensitive technique for the detection of nerve compression. Finally, ENMG cannot differentiate entrapment neuropathy from other causes of pudendal nerve lesions (stretching caused by pelvic surgery, obstetrical damage, chronic constipation, etc.). The diagnosis of pudendal neuralgia is mainly based on specific clinical features. Perineal ENMG has a limited sensitivity and specificity, does not give direct information about pain mechanisms, and can only provide additional, but not definitive, clues about the diagnosis of pudendal nerve entrapment syndrome. The value of ENMG is the objective assessment of pudendal motor innervation when surgical decompression is under consideration. Perineal ENMG can also be used to predict surgical outcome, but usually cannot localize the site of compression and is of no value in intraoperative monitoring.     

A cerebral hemisphere influence on cutaneous vasomotor reflexes in humans.

Cutaneous vasomotor reflexes (CVR), the transient waves of cutaneous vasoconstriction after stimuli, such as a cough, were recorded from the digits of patients with unilateral frontoparietal lesions using a laser doppler flowmeter. Vasoconstriction was 6-15 times greater on the fingers contralateral to the lesions, an effect which was independent of the temperature difference between limbs. CVRs may be tonically inhibited under normal circumstances by control from the cerebral hemispheres.