Pudendal Somatosensory Evoked Potentials Research Articles

The assessment of erectile dysfunction after radical prostatectomy using pudendal somatosensory evoked potential.

Erectile dysfunction in patients who underwent radical prostatectomy was evaluated with pudendal somatosensory evoked potentials (PSEP) to measure and predict erectile dysfunction objectively. Fifty-seven patients who completed requirements were included in the study. Patients were divided into 2 groups (potency/non-potency). Erectile function recovery was defined as question 2 and 3 on the IIEF-5 questionnaire at 12 months after surgery. The two-channel PSEP test was performed at the day before RP and 3-6 months after RP. Twenty patients were assigned to the potency group and 37 to the non-potency group. Mean age was less in the potency group. Other clinical variables were similar in two groups. The non-potency group had prolonged lumbar and cortical latencies in postoperative PSEP, and the mean differences of latencies between pre- and postoperative PSEP in lumbar and cortical regions were also greater in the non-potency group. Logistic regression analysis showed that age, lumbar post-operative latency, cortical post-operative latency, and difference of latency in lumbar region were associated with non-potency; odds ratios were 1.292 (p = 0.018), 0.425 (p = 0.047), 1.637 (p < 0.001), and 3.272 (p = 0.010), respectively. This study suggests that PSEP is an effective means of evaluating erectile dysfunction in prostate cancer patients after surgery.

Intraoperative Neuromonitoring for Pediatric Pelvic Tumors.

BackgroundTumors of the pre-sacral and sacral spaces are a rare occurrence in children. Total tumor excision is required due to the significant risk of relapse in the event of partial surgery, but the surgical procedure may lead to postoperative problems such as urinary, sexual, and anorectal dysfunctions. Intraoperative neuromonitoring (IONM) has gained popularity in recent years as a strategy for preventing the onset of neurologic impairments by combining several neurophysiological techniques. The aim of our study is to describe the experience of Bambino Gesù Children’s Hospital in the use of IONM in pediatric pelvic surgery.Materials and MethodsThe data of patients treated for pelvic malignancies at Bambino Gesù Children’s Hospital from 2015 to 2019 were retrospectively collected. All patients were assessed from a neurologic and neuro-urologic point of view at different time-points (before and immediately after surgery, after 6 months, and 1-year follow-up). They were all monitored during a surgical procedure using multimodal IONM including transcranial motor evoked potentials (TcMEP), triggered-EMG (t-EMG), pudendal somatosensory evoked potentials (PSSEP), and bulbocavernosus reflex (BCR).ResultsDuring the study period, ten children underwent pelvic tumor removal at our Institution. In all cases, intraoperative neurophysiological recordings were stable and feasible. The preservation of neurophysiological response at the same intensity during surgical procedures correlated with no new deficits for all neurophysiological techniques.DiscussionAlthough the impact of the IONM on surgical strategies and clinical follow-up is unknown, this preliminary experience suggests that the appropriate use of several neurophysiological techniques can influence both the radicality of pelvic tumor removal and the neurological and urological outcome at clinical follow-up. Finally, because of the highly complex anatomy and inter-individual variances, this is especially useful in this type of surgery.

Dynamic Somatosensory Evoked Potential and Magnetic Resonance Imaging in Pudendal Neuropathy

Aim: Pudendal neuropathy (PN) is a common cause of chronic perineal pain and usually diagnosed long after the onset of symptoms. Diagnostic work-up of PN mainly includes radiologic and neurophysiological studies. However, there is no established diagnostic test to confirm the clinical diagnosis. This study aims to evaluate the correlation between the dynamic pudendal somatosensory evoked potential (SEP) and pudendal magnetic resonance imaging (MRI) in patients with PN diagnosed clinically based on Nantes criteria as the gold standard for comparison. Methods: Forty-three patients (25 females, 18 males) were included in the study. Dynamic pudendal SEP as a novel method, which includes both provocative positioning and stimulation of each side separately, and pudendal MRI were performed in each patient. Results: Dynamic pudendal SEPs were found to be abnormal in 42, normal in 12 of the 54 clinically symptomatic nerves and abnormal in 2, normal in 30 of the 32 clinically asymptomatic nerves. Pudendal MRI was abnormal in 19, normal in 35 of the 54 clinically symptomatic nerves and abnormal in 8 and normal in 24 of the 32 clinically asymptomatic nerves. There was 84% agreement between clinical diagnosis and dynamic pudendal SEP (high sensitivity and specificity), 49% agreement between clinical diagnosis and pudendal MRI (low sensitivity and acceptable specificity), 53% agreement between dynamic pudendal SEP and pudendal MRI. Conclusions: The novel dynamic pudendal SEP method seems to be useful in supporting the clinical diagnosis of PN, while pudendal MRI lacks sufficient sensitivity to be used alone in diagnosis of PN.

Effect of electroacupuncture of Taichong (LR3) on somatosensory evoked cortical potentials in healthy volunteers

To explore the excitatory effect of the sensory cortex through somatic electroacupuncture (EA) stimulation at Taichong (LR3). Ten healthy volunteer men ranging in age from 20 to 50 years were enrolled in this study. EA (2 Hz, a tolerable strength) was applied to the left LR3. Before and after EA, the somatosensory evoked potential (SEP) from the Cz' area of the scalp was recorded by electrical stimulation of the bilateral dorsal penile nerves and the indentation behind the medial malleolus of the foot, termed as the pudendal SEP (PSEP) and lower extremity SEP (LSEP), respectively. The amplitude of the left LSEP induced by stimulation of the left medial malleolus was significantly increased after EA (P < 0.05), but there were no significant changes in the latency of LSEP and PSEP, and the amplitude of right LSEP evoked by stimulation of the left medial malleolus, and that of the PSEP. EA at LR3 increases the excitability of the contralateral cerebral sensory cortex (lower extremity area), but has no effect on the adjacent sensory cortex (genital area).

Transcutaneous stimulation of the posterior tibial nerve for treating refractory urge incontinence of idiopathic and neurogenic origin

ObjectiveTo assess the efficacy of treatment with transcutaneous posterior tibial nerve stimulation (TPTNS) in patients with urge urinary incontinence, of neurogenic or nonneurogenic origin, refractory to first-line therapeutic options. Material and methodsWe included 65 patients with urge urinary incontinence refractory to medical treatment. A case history review, a urodynamic study and a somatosensory evoked potentials (SEP) study were conducted before the TPTNS, studying the functional urological condition by means of a voiding diary. The treatment consisted of 10 weekly sessions of TPTNS lasting 30min. ResultsSome 57.7% of the patients showed abnormal tibial SEPs, and 42% showed abnormal pudendal SEPs. A statistically significant symptomatic improvement was observed in all clinical parameters after treatment with TPTNS, and 66% of the patients showed an overall improvement, regardless of sex, the presence of underlying neurological disorders, detrusor hyperactivity in the urodynamic study or SEP disorders. There were no adverse effects during the treatment. ConclusionsTPTNS is an effective and well tolerated treatment in patients with urge incontinence refractory to first-line therapies and should be offered early in the treatment strategy. New studies are needed to identify the optimal parameters of stimulation, the most effective treatment protocols and long-term efficacy, as well as its applicability to patients with a neurogenic substrate.

Estimulación transcutánea del nervio tibial posterior en el tratamiento de la incontinencia urinaria de urgencia refractaria, de origen idiopático y neurógenico

ObjectiveTo assess the efficacy of treatment with transcutaneous posterior tibial nerve stimulation (TPTNS) in patients with urge urinary incontinence, of neurogenic or nonneurogenic origin, refractory to first-line therapeutic options. Material and methodsWe included 65 patients with urge urinary incontinence refractory to medical treatment. A case history review, a urodynamic study and a somatosensory evoked potentials (SEP) study were conducted before the TPTNS, studying the functional urological condition by means of a voiding diary. The treatment consisted of 10 weekly sessions of TPTNS lasting 30minutes. ResultsSome 57.7% of the patients showed abnormal tibial SEPs, and 42% showed abnormal pudendal SEPs. A statistically significant symptomatic improvement was observed in all clinical parameters after treatment with TPTNS, and 66% of the patients showed an overall improvement, regardless of sex, the presence of underlying neurological disorders, detrusor hyperactivity in the urodynamic study or SEP disorders. There were no adverse effects during the treatment. ConclusionsTPTNS is an effective and well tolerated treatment in patients with urge incontinence refractory to first-line therapies and should be offered early in the treatment strategy. New studies are needed to identify the optimal parameters of stimulation, the most effective treatment protocols and long-term efficacy, as well as its applicability to patients with a neurogenic substrate.

A Novel Electrophysiological Method in the Diagnosis of Pudendal Neuropathy: Position-related Changes in Pudendal Sensory Evoked Potentials

To examine the diagnostic value of pudendal somatosensory evoked potentials (SEPs) in pudendal nerve entrapment (PNE) neuropathy by stimulating the 2 sides separately after provocation by a standard sitting position. Routine pudendal SEPs performed in the supine position with bilateral simultaneous stimulation may fail to show the abnormality because the complaints of PNE appear or worsen in the sitting position. Forty-nine patients with PNE and 16 controls were included. SEP recordings were performed by stimulating the dorsal nerve of penis or clitoris on either side. The recordings were performed at the initial supine position, at the beginning and end of the provocation by sitting position, and at the second supine position. Amplitude loss in the SEP responses after prolonged sitting was significantly more pronounced on the symptomatic sides of the patients. Approximately 45% decrease in the SEP amplitude or an amplitude value less than 1.5 µV at the end of sitting are the parameters to be used with high selectivity. The dynamic pudendal SEP study described herein seems to be more helpful in PNE diagnosis than in conventional SEPs.

ID 49 – Electrophysiological tests in diagnosis of pelvic floor disorders

Objective The aim of this study was to examine whether pelvic floor electrophysiological (PFE) tests contribute to diagnosis of pelvic floor disorders. Methods Clinical information and PFE data of 18 patients consecutively referred for assessment of possible pelvic floor disorders, were analysed retrospectively. The results of pudendal somatosensory evoked potentials (SEP), penilo/cliterocavernosus reflex, electromyography (EMG) of external anal sphincter (EAS) muscle were analysed. The clinical course of the patients and the influence of the electrophysiological results to clinicians’ decision were reviewed from patient files. Results Ten of the 18 patients had abnormal PFE tests showing pudendal neuropathy, and all 10 had delayed latencies or absent responses of the penilo/cliterocavernosus reflex. EMG of EAS was abnormal in 8 and pudendal SEP in 2 patients. For 10 patients, the electrophysiological assessment contributed to the diagnosis by confirming the referral theory of pelvic floor disorder. For the remaining patients the assessment enabled the clinician to change the diagnosis, initiate further examination, or treatment. Conclusion Pelvic floor electrophysiology may contribute to the diagnosis of pelvic floor disorders. Penilo/cliterocavernosus reflex is suggested to be a sensitive test. Key message Electrophysiological tests have an impact on the diagnosis or further course of pelvic floor disorders.

ID 10 – A novel electrophysiological method in the diagnosis of pudendal neuropathy: Position related changes in pudendal sensory evoked potentials

Pudendal nerve entrapment (PNE) is a common cause of resistant and disabling perineal pain. Although it is diagnosed clinically, neurophysiological tests are used for the diagnosis. Since the complaints worsen in the sitting position, routine pudendal somatosensory evoked potentials (SEP) performed in the supine position with midline stimulation may fail to show the PNE. We hypothesized that diagnostic value of SEP can be increased by stimulating the right and left sides separately along with provocation by maintained sitting position (dynamic SEP). Forty-nine patients with PNE and 16 healthy controls were included. SEP recordings were performed by stimulating the dorsal nerve of penis/clitoris on either side. The recordings were performed at the first supine position, at the beginning and end of a standardized sitting posture and at the second supine position. Regarding the patients with recordable responses, we might suggest that approximately 45% decrease in SEP amplitude or an amplitude value less than 1.5 mV at the termination of the sitting position (and their reversal with switching to the supine position again) are the parameters to be used with high selectivity. The dynamic pudendal SEP study described herein seems to be more valuable in PNE diagnosis than conventional SEPs.

Sex differences in pudendal somatosensory evoked potentials

Somatosensory evoked potentials (SEPs) of the pudendal nerve are a well-established diagnostic tool for the evaluation of pelvic floor disorders. However, the possible influence of sex differences on response latencies has not been established yet. The aim of this study was to standardize the procedures and to evaluate possible effects of gender differences on anal and penile/clitoral SEPs. The anal and dorsal penile/clitoral SEPs were recorded in 84 healthy subjects (40 males and 44 females; mean age 47.9±16.6years, range 16-81years; mean height 168.3±20.3cm, range 155-187cm). Pudendal SEPs were evoked with a bipolar surface electrode stimulating the clitoris or the base of the penis and the anal orifice and recorded using scalp electrodes. The latency of the first positive component (P1) was measured. The effect and possible interaction of (a) stimulation site and (b) gender on the two variables was explored by multivariate analysis of variance (MANOVA). The examination was well tolerated and a reproducible waveform of sufficient quality was obtained in all the subjects examined. In the female subjects, a mean cortical P1 latency of 37.0±2.6 and 36.4±3.2ms for anal and clitoral stimulation, respectively, was found. In the male subjects, the cortical latencies were 38.0±3.5ms for the anal stimulation and 40.2±3.7ms for the penile stimulation. At MANOVA, a statistically significant main effect of stimulation site and gender as well as a significant interaction between the two variables was found. Anal and dorsal penile/clitoral SEPs represent a well-tolerated and reproducible method to assess the functional integrity of the sensory pathways in male and female subjects. Obtaining sex-specific reference data, by individual electrophysiological testing, is highly recommended because of significant latency differences between males and females, at least as far as penile/clitoral responses are concerned.

Sexual dysfunction following surgery for rectal cancer - a clinical and neurophysiological study

BackgroundSexual dysfunction following surgery for rectal cancer may be frequent and often severe. The aim of the present study is to evaluate the occurrence of this complication from both a clinical point of view and by means of neurophysiological tests.MethodsWe studied a group of 57 patients submitted to rectal resection for adenocarcinoma. All the patients underwent neurological, psychological and the following neurophysiological tests: sacral reflex (SR), pudendal somatosensory evoked potentials (PEPs), motor evoked potential (MEPs) and sympathetic skin responses (SSRs). The results were compared with a control group of 67 rectal cancer patients studied before surgery. Only 10 of these patients could be studied both pre- and postoperatively. 10 patients submitted to high dose preoperative chemoradiation were studied to evaluate the effect of this treatment on sexual function. Statistical analysis was performed by means of the two-tailed Student's t test for paired observations and k concordance test.Results59.6% of patients operated reported sexual dysfunction, while this symptom occurred in 16.4% in the control group. Moreover, a significantly higher rate of alterations of the neurophysiological tests and longer mean latencies of the SR, PEPs, MEPs and SSRs were observed in the patients who had undergone resection. In the 10 patients studied both pre and post-surgery impotence occurred in 6 of them and the mean latencies of SSRs were longer after operation. In the 10 patients studied pre and post chemoradiation impotence occurred in 1 patient only, showing the mild effect of these treatments on sexual function.ConclusionPatients operated showed severe sexual dysfunctions. The neurophysiological test may be a useful tool to investigate this complication. The neurological damage could be monitored to decide the rehabilitation strategy.

Pudendal somatosensory evoked potentials in normal women

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. 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. 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. 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.

A combined urodynamic and electrophysiological study of diabetic cystopathy

The aim of this study is to compare urodynamics and electrophysiological studies in the diagnosis of diabetic cystopathy. In this prospective study are included twenty six patients with diabetes mellitus diagnosed at least since 5 years; 17 patients with diabetes type II and 9 with type I. They were divided in two groups in respect to lower urinary tract symptoms (LUTS) and signs suggestive of lower urinary tract dysfunction (LUTD) according to the ICS standardization. Patients with LUTS/LUTD were included in Group A and patients without LUTS/LUTD in Group B. Patients underwent different studies: urodynamic, somatosensory evoked potentials (SSEP) of tibial and pudendal nerves, bulbocavernosus reflex (BCR), bulbocavernosus muscles' electromyography and motor evoked potentials after transcranial magnetic stimulation to indirectly investigate bladder's innervation. Abnormal urodynamics were found in 13 patients of group A (92.9%) and in 5 of group B (47.1%). This difference was statistically significant (P=0.009). Abnormally prolonged latency of P40 of tibial SSEP was found in 11 patients of group A (78.6%) and in 4 of group B (33.3%) and this difference was also statistically significant (P=0.04). Differences between the two groups concerning: i) peripheral polyneuropathy; ii) pudendal SSEP, iii) dysfunction of central nervous system and iv) abnormal BCR were not statistically significant. The study of tibial SSEP is an easily performed test and it is well correlated to abnormal urodynamics in diabetic patients with and without LUTD/LUTS.

Neurophysiological Evidence May Predict the Outcome of Sacral Neuromodulation

Chronic stimulation of the sacral nerves has now become one of the most accepted stimulation therapies for functional lower urinary tract symptoms refractory to conservative treatment. Despite the existence of a large amount of literature on sacral neuromodulation (SNM) showing a fairly high percent of significant improvement in clinical outcome there are few experimental studies of SNM stimulus parameters and/or neurophysiological monitoring. We evaluated the specific action of SNM on the primary sensory cortical area. Somatosensory evoked potentials (SEPs) of the pudendal and posterior tibial nerves were evaluated in patients implanted with a monolateral permanent quadripolar electrode. A total of 24 patients underwent stage 1 monolateral sacral nerve implantation. Three SEP patterns were evaluated; namely before implantation, 1 month after stage 1 with stimulation set at 21 Hz and again with a pulse rate of 40 Hz. In all patients SNM produced a significant decrease in pudendal SEP latency of the first positive deflection between baseline SNM stimulation at different pulse rates at the ipsilateral and contralateral implant sites. This finding was evidence of the effect of S3 SNM on the cortical sensory area and the specificity of pudendal SEPs in measuring how SNM modulates the afferent pathway from the spinal nerve to the cortical sensory area. Our study confirms previous observations that SNM acts by the afferent pathway at the cortical site level and it sheds light on so-called idiopathic lower urinary tract symptoms. A modification of SEPs induced by SNM seems to be a prognostic factor of clinical outcomes. The action of SNM on the afferent pathway from the sacral area to the somatosensory cortex is specific and neurophysiological evaluation via pudendal SEPs provides evidence to this effect.

Physiologic studies of male sexual dysfunction in multiple sclerosis.

We conducted this investigation to better define the neural disruptions that result in sexual dysfunction in men with multiple sclerosis (MS), using genital electrodiagnostic testing and nocturnal penile tumescence and rigidity monitoring. Thirteen men with MS and sexual dysfunction were recruited for the study. Twelve healthy, sexually potent men were enrolled as controls. All underwent pudendal somatosensory evoked potential (SEP) testing using standard methods, and a new modification to isolate the right and left dorsal nerves of the penis. RigiScan testing was performed on the MS subjects to assess nocturnal erectile function. Unilateral and bilateral DNP SEPs were able to be performed on the control subjects. In all but one MS subjects, DNP SEP abnormalities were found. Three men had normal latency bilateral DNP SEP latencies, but on unilateral DNP testing, abnormalities were identified. Seven men, including those with abnormal or absent SEP latencies, had normal nocturnal erectile activity. There was no correlation between overall functional status, presence of abnormal or absent SEP, and quality of nocturnal erectile activity. Genital SEP abnormalties are common in men with MS and sexual dysfunction. Unilateral DNP SEP testing was more sensitive in identifying abnormalities than the standard method of pudendal SEP testing. One of the causes of sexual dysfunction in men with MS may be due to genital somatosensory pathway disruption, with sparing of the efferent tracts in some men.

Penile and perianal pudendal nerve somatosensory evoked potentials in the diagnosis of erectile dysfunction

Neurophysiologic examinations in differential diagnosis of erectile dysfunction comprise electromyogramme of the pelvic floor, pudendal nerve terminal motor latency (PNTML) and evaluation of pudendal somatosensory evoked potentials (SSEP). We focused our interest on comparing diagnostic importance of penile and perianal pudendal nerve SSEP. We examined 20 patients suffering from erectile dysfunction and 20 patients without any manifestation of impotence. The stimulus was administered using penile ring electrodes at the base of the penis (cathode) and distally on the penis shaft (anode), as well as a perianal surface electrode applied at 3 o'clock in lithotomy position and 5 cm laterally on the gluteal skin. The potentials were recorded with intradermal needle electrodes at C(z)-2 cm (different) and F(z) (indifferent). 500 stimuli were averaged for a single tracing. The stimulus strength was set at an average of 3-4 times the stimulus threshold. Cortical latency of P 40 ranged from 39.0 to 45.6 ms (penile) and from 33.6 to 43.2 ms (perianal) in the control group, in the patient group latencies ranged from 38.8 to 51.6 (penile) and 34.0 to 44.8 ms (perianal). In two patients no potential was recordable after perianal stimulation, one patient showed a marked prolongation of the penile response with a normal perianal latency. Penile and perianal latencies of P 40 were significantly prolonged in the patient group compared to the control group (P<0.05). The combination of penile and perianal pudendal SSEP may provide valuable additional information in differential diagnosis of erectile dysfunction, especially allowing to identify different sites of neurogenic lesions. In contrast to perianal pudendal SSEP, penile stimulation may help to discover pathologic changes in the distal course of the pudendal nerve, especially the dorsal nerve of the penis.

Neurophysiological study of primary nocturnal enuresis

The purpose of this study was to investigate nervous system involvement in primary nocturnal enuresis by using electrophysiological techniques. Nineteen boys with primary nocturnal enuresis and 25 boys without uroneurological abnormalities were included. Data about their psychomotor development, micturition, and defecation were obtained by interviewing the boys and their parents. The penile sensory threshold for electrical stimuli was determined. Single and averaged bulbocavernosus reflex (BCR), and averaged pudendal somatosensory evoked potentials (PSEP) to electrical stimulation, were recorded. The only statistically significant difference found in enuretic children was longer latencies of averaged BCR to single electrical stimulation (P = 0.03). No significant BCR latency differences to stimulation with double electrical pulses and no PSEP latency differences were found. By using electrophysiological techniques, differences between the enuretic and control group of boys were demonstrated. Our results can be interpreted as indicating hypoexcitability of sphincter nuclei. Along with the reported hyperexcitability of bladder motor nuclei, a minor dysfunction in the neurocontrol of the lower urinary tract, in at least a subgroup of enuretic children, can be postulated. Neurourol. Urodynam. 18:93–98, 1999. © 1999 Wiley-Liss, Inc.

Neurophysiological study of primary nocturnal enuresis

The purpose of this study was to investigate nervous system involvement in primary nocturnal enuresis by using electrophysiological techniques. Nineteen boys with primary nocturnal enuresis and 25 boys without uroneurological abnormalities were included. Data about their psychomotor development, micturition, and defecation were obtained by interviewing the boys and their parents. The penile sensory threshold for electrical stimuli was determined. Single and averaged bulbocavernosus reflex (BCR), and averaged pudendal somatosensory evoked potentials (PSEP) to electrical stimulation, were recorded. The only statistically significant difference found in enuretic children was longer latencies of averaged BCR to single electrical stimulation (P = 0.03). No significant BCR latency differences to stimulation with double electrical pulses and no PSEP latency differences were found. By using electrophysiological techniques, differences between the enuretic and control group of boys were demonstrated. Our results can be interpreted as indicating hypoexcitability of sphincter nuclei. Along with the reported hyperexcitability of bladder motor nuclei, a minor dysfunction in the neurocontrol of the lower urinary tract, in at least a subgroup of enuretic children, can be postulated.

Neurophysiological evaluation of sexual dysfunction in patients operated for colorectal cancer.

Sexual dysfunction after colorectal cancer surgery may be severe and occurs in 25% to 100% of cases. Thirty-eight patients underwent colorectal resection; eight (21%) who were totally impotent and two (5%) who had ejaculatory failure were therefore studied to better understand the neurophysiological alterations related to this type of surgery. The patients were evaluated after surgery with electrophysiological testing, including examination of the sacral reflex (SR), pudendal somatosensory evoked potential (PEP), and motor evoked potential (MEP) responses. Sudomotor skin response (SSR) was also studied in a group of patients. Of the 38 patients studied, 29 showed abnormalities: six of SR, three of PEP, six of MEP, and fourteen of SSR. Only a combination of all these tests permits correct evaluation of the sexual dysfunction.

Anorectal functions in patients with spinal cord injury.

We wished to establish anorectal functions in patients with spinal cord lesions, related to the level of lesion and its completeness. We also wished to determine the value of neurophysiological tests for completeness of transsections in comparison with manometry and visceral sensory testing. In 32 patients (31.5 +/- 14.1 years, 25 males) with spinal trauma, completeness of transsection was assessed clinically. In 16 of these patients (30 +/- 15.6 years, nine males), a neurological work-up included recording of somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) from the pudendal nerve within the first week after trauma. Also, anal sphincter EMG and pudendal nerve terminal motor latency (PNTML) were assessed. All patients also underwent conventional anorectal manometry and visceral sensory testing. Of all 32 patients, 15 were judged as 'complete' based on their clinical signs. Of those 16 tested neurologically, seven were labelled 'complete' since no MEP or SEP were detectable; one had pudendal SEP and MEP present, while SEP were present but delayed (47.0 +/- 8.8 msec) in the remaining patients. In four of these patients, also MEP were recorded (27.9 +/- 5.2 msec) and normal. PNTML was present in 12/16 patients independent of the completeness of lesion, and was rated normal in nine and delayed in three patients. EMG was normal in five, and pathological in 11 cases. In 5/15 cases of those judged as 'complete' (in 3/7 evaluated neurologically), visceral sensory testing revealed a minimal threshold for rectal perception of distension of 44 mL (range: 10-130), which sometimes was also perceived as urge to defecate. In a further case, manometry showed major voluntary action of the anal sphincter. These patients had lesions at all levels of the spinal column, ranging from cervical (C4,C6,C7) via thoratical (2 x T7,T8,T12) to lumbar segments. Anorectal function testing, and specifically visceral sensory testing may be superior to neurological assessment of 'completeness' of spinal cord lesions. It may be that visceral afferent pathways others than spinothalamic tract are involved in rectal perception that are less accessible to conventional neurophysiological diagnostic work-up.