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.

Sensory conduction velocity of dorsal nerve of the penis during pharmacoerection: a more physiological technique?

OBJECTIVE: Sensory conduction velocity (SCV) of the dorsal nerve of the penis is technically difficult to perform at rest and very slow SCV has been observed in the literature. This study evaluates the effect of pharmacoerection on the SCV measurement. METHODS: Twenty-four men, 16 with a normal neurologic examination, 8 with a diabetic neuropathy, were studied at rest and after a 20-micrograms injection of prostaglandin E1. RESULTS: Only 5 subjects had a recordable potential at rest. The mean SCV increased from 32.3 +/- 6.7 to 47.4 +/- 8.2 m/s after injection. Nine had only a recordable potential after injection. Ten had no potential at all, but 6 of them had a diabetic neuropathy. CONCLUSION: Pharmacoerection was helpful in 37.5% of the subjects to obtain a sensory potential. Moreover, pharmacoerection may be the best way of calculating dorsal nerve SCV, as 47.4 m/s is what should be expected for a large myelinated nerve. This may be due to a correct interelectrode distance measurement as full tumescence may straighten the nerve at an individual and physiological length.

Paradoxical contraction of pelvic floor muscles: clinical significance.

Paradoxical contraction of pelvic floor muscles during defecation straining has been said to be a cause of constipation and difficulty in passing feces. Nevertheless, controversies about its clinical significance still remained. Twenty patients with constipation and electromyographic evidence of paradoxical contraction of both puborectalis and external anal sphincter were investigated. An anorectal manometry performed in 17 confirmed the paradoxical contraction in 13 (76%). Electromyography revealed neurogenic signs in 11. Defecography demonstrated the paradoxical contraction in 6 only, but, together with barium enema and colon transit time, showed associated anorectal disorders in 9 patients. Twenty control patients were also studied. None had difficulty defecating. Nevertheless, 8 of them (40%) had paradoxical contraction. These observations suggest that paradoxical contraction of pelvic floor muscles may by asymptomatic and that another cause of emptying difficulties has always to be looked for.

[Paretic syndrome of spinal stenosis]. / Le syndrome parétique du canal lombaire étroit.

We report a case of painless progressive leg amyotrophy without intermittent claudication due to spinal lumbar stenosis. Our attention was drawn to the lumbar region because of the discrepancy between normal leg sensory potentials and altered somatosensory evoked potentials, prompting us to perform a myelography. The rapid though partial, clinical improvement following decompressive surgery suggested that some of the symptoms may have been due to a reversible nerve conduction block.

Impotence due to corporeal veno-occlusive dysfunction: long-term follow-up of venous surgery.

Corporeal veno-occlusive dysfunction is an important cause of organic impotence and is characterized by increased flow rates to create and to maintain erection during artificial erection produced by intracavernous saline infusion. Sixty-seven patients with this erectile insufficiency underwent penile ligature-resection of deep dorsal vein between 1982 and 1986, and were evaluated by nocturnal plethysmography, pharmacocavernometry as well as a questionnaire about their sexual life for long-term follow-up. The surgical procedure was controlled in the operating room by reduction of the erectile flow rates. Thirty-one patients were potent postoperatively and were able to have satisfactory intercourse. Results after resection were slightly better than after simple ligation of the deep dorsal vein. Four patients had penile glans insensibility resulting from the surgical dissection. There were 7 relapses several months after the procedure due to leakage through other deeper veins. Eight failures were due to additional psychogenic disorders or to neurologic disease not accurately diagnosed before the treatment because they all developed normal papaverine-induced erection after venous surgery while before it they only developed a slight tumescence. Reduction of the erectile flow rates within normal values was impossible during surgery in 3 patients. Eleven failures were due to concomitant arterial disease. Resection of the deep dorsal vein can restore penile erection in patients with cavernovenous leakage in about 50% of well-selected patients.

Urinary retention due to sacral myeloradiculitis: a clinical and neurophysiological study.

We report 5 cases of sacral myeloradiculitis presenting with transient urinary retention. Neurophysiological testing, including bulbocavernosus reflex, pudendal evoked response and external anal sphincter electromyography, was performed. Parasympathetic pelvic nerves, pudendal nerves as well as the spinal cord seem to be involved to various degrees in this infrequent disorder.

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.

[Neurophysiological studies in 200 impotent men: the value of the bulbocavernous reflex and of penile evoked potentials]. / Investigation neurophysiologique chez 200 hommes impuissants: intérêt du réflexe bulbocaverneux et des potentiels évoqués péniens.

After having investigated 200 males with impotence, the authors conclude that the study of the bulbocavernous reflex and the penile evoked potentials are of a certain importance when a neurological origin is suspected as the cause of the impotence. The usual urological investigations during the work-up of impotence should always be carried out in order to improve the insight into the relationships between the different examinations.

Neurophysiological investigations of two hundred men with erectile dysfunction. Interest of bulbocavernosus reflex and pudendal evoked responses.

Two-Hundred consecutive patients complaining of impotence have had complete urological and neurophysiological investigations to determine a possible organic cause of their sexual dysfunction. All patients had urological and neurological history and examination: nocturnal penile plethysmography, papaverine intracavernosus injection, penile arterial doppler and/or arteriography, cavernography-cavernometry, serum hormonal levels, and bulbocavernosus reflex (BCR). Peripheral conduction velocities and pudendal-evoked responses (PER) were also performed if neurological history or examination and/or BCR were abnormal. Only 30 patients (15%) had an abnormal BCR. In 17 patients, a neurological associated disorder was found. Four patients had normal erections during plethysmography, despite their complaints. Nine patients with an isolated prolonged BCR also presented a vascular abnormality that could explain impotence. Abnormal PER was observed only in 6 patients, 4 of them with a prolonged BCR as well. These results suggest that PER is not an interesting neurophysiological routine test for the diagnosis of neurogenic impotence and that the relationship between an abnormal BCR and neurogenic impotence is doubtful.

Role of the bulbocavernosus muscles on the mechanism of human erection.

The role of the human bulbocavernosus muscles on the intracavernous pressure and on the venous return were investigated during artificial erection. Contractions of these muscles were voluntary or produced by dorsal nerve stimulation. During such contractions, elevations in intracavernous pressure and a decrease in the erectile flow rates to produce and to maintain the erection were observed. These results demonstrate involvement of the bulbocavernosus muscles in the process of penile rigidity and suggest that they could participate in the mechanism of rigidity during intercourse.

The somatosensory central conduction time: physiological considerations and normative data.

The somatosensory central conduction time (CCT) can be measured from the peak of N13 to the peak of N20 (peak CCT) or from the onset of N11 to the onset of N20 (onset CCT). The onset and peak CCT were measured concomitantly in 40 normal subjects and the mean peak CCT was significantly shorter than the mean onset CCT. Records with different reference electrodes (linked earlobes, F3, over the ipsilateral parietal scalp, non-cephalic reference in some subjects) showed no significant latency change of the N11 onset, the N20 onset, the peak and onset CCT in contrast with the significant latency changes of the N13 and N20 peak with different montages. The onset CCT was divided by the onset of the P14 far-field in 2 parameters, the N11-P14 interval predominantly concerned with spinal conduction and the P14-N20 interval which reflected only supraspinal conduction. The onset and peak CCT, the N11-P14 and P14-N20 intervals were not correlated with height or age. Three independent recording sessions over 1 year in 16 subjects showed that the parameters were reproducible. From the physiological point of view the onset and peak CCT are different parameters and the anatomical correlates of both parameters are discussed.

Brainstem auditory evoked potential abnormalities in myelomeningocoele in the older child.

Brainstem auditory evoked potentials and clinical findings were examined in 18 children over the age of 5 years who were born with myelomeningocoele which was closed at birth, and whose hydrocephalus was managed by long term shunting in most of them. The potentials were compared with age and sex matched normal subjects and with four patients with hydrocephalus only. All but one had an abnormal brainstem auditory evoked potential with 72% showing a delay in the II-V and I-V interpeak latencies of more than three standard deviations. It is proposed that the abnormalities are a reflection of brainstem dysgenesis which is part of an associated Arnold-Chiari malformation, though the malformation was clinically asymptomatic in all. The usefulness of the brainstem auditory evoked potential for assessing the course of hydrocephalus and for predicting symptomatic Arnold-Chiari malformation is questioned.

Benign transient urinary retention.

Three cases of acute urinary retention due to sacral myeloradiculitis are described. The authors stress the importance of diagnosing this rare and benign condition, which, in the past, has too often been mislabelled as either psychogenic or the first manifestation of a demyelinating disease.

Unusual pattern of somatosensory and brain-stem auditory evoked potentials after cardio-respiratory arrest.

Two patients in coma after cardio-pulmonary arrest showed bilateral absence of all brain-stem auditory evoked potentials contrasting with normal brain-stem reflexes and normal somatosensory cortical evoked potentials. In both patients pre-existing dysfunction of peripheral auditory structures could be ruled out. Subsequent neuropathological analysis showed that the anoxic-ischaemic lesions were restricted to Sommer's sector and the Purkinje cells. These unusual data suggest the hypothesis that a severe hypoxic-ischaemic insult may impair cochlear function and interfere with the activation of the intact auditory pathways.