Neurophysiology of the pelvic floor in clinical practice: a systematic literature review.

Neurophysiological testing of the pelvic floor is recognized as an essential tool to identify pathophysiological mechanisms of pelvic floor disorders, support clinical diagnosis, and aid in therapeutic decisions. Nevertheless, the diagnostic value of these tests in specific neurological diseases of the pelvic floor is not completely clarified. Seeking to fill this gap, the members of the Neurophysiology of the Pelvic Floor Study Group of the Italian Clinical Neurophysiology Society performed a systematic review of the literature to gather available evidence for and against the utility of neurophysiological tests. Our findings confirm the utility of some tests in specific clinical conditions [e.g. concentric needle electromyography, evaluation of sacral reflexes and of pudendal somatosensory evoked potentials (pSEPs) in cauda equina and conus medullaris lesions, and evaluation of pSEPs and perineal sympathetic skin response in spinal cord lesions], and support their use in clinical practice. Other tests, particularly those not currently supported by high-level evidence, when employed in individual patients, should be evaluated in the overall clinical context, or otherwise used for research purposes.

Reversal of profound and "deep" residual rocuronium-induced neuromuscular blockade by sugammadex: a neurophysiological study.

BACKGROUND: Sugammadex is the first of a new class of selective relaxant binding drugs developed for the rapid and complete reversal of neuromuscular blockade (NMB) induced by the aminosteroid neuromuscular blocking drugs rocuronium and vecuronium. Neuromuscular blocking drugs block the transmission from the peripheral nerve to the muscle units, with reduction and disappearance of the evoked electromyographic activity. Usually, neuromuscular monitoring for the investigational reversal drug is performed by calibrated acceleromyography. The efficacy of sugammadex in reversing profound and "deep" residual rocuronium-induced NMB using myogenic motor evoked potentials (mMEPs) monitoring was evaluated. METHODS: In this prospective trial, 30 consenting patients undergoing propofol-remifentanil anesthesia for spine surgery were enrolled and divided into two groups: Group 1, reversal of profound NMB (sugammadex 16 mg/Kg, 3 minutes after rocuronium 1.2 mg/Kg) and Group 2, reversal of "deep" residual NMB (sugammadex 4 mg/Kg, 15 minutes after rocuronium 0.6 mg/Kg). Myogenic MEPs registrations of upper and lower limbs and the diaphragm were performed, as well as TOF monitoring. RESULTS: After injection of 4 mg/Kg of sugammadex, the means of recovery time of the basal mMEPs amplitudes (diaphragm, and lower limbs and upper limbs) were 124±9.6, 143±163, 151±207 sec, respectively whereas after 16 mg/Kg of sugammadex the times were 109±13.8, 124±0.6, and 135±14.1 sec. Times to TOF ratio 0.9 were 114±75 and 186±105 sec in Group 1 and 2, respectively. No serious adverse effects related to sugammadex and to electrical stimulation were reported. No reoccurrence of neuromuscular block was observed. CONCLUSION: Neurophysiological monitoring using mMEPs confirmed that sugammadex provided a complete recovery from profound and "deep" residual rocuronium-induced neuromuscular blockade.

Biomechanical and electromyographic assessment of spastic hypertonus in motor complete traumatic spinal cord-injured individuals.

STUDY DESIGN: Between-groups design with repeated measures. OBJECTIVE: To quantify spastic hypertonia in spinal cord-injured (SCI) individuals. SETTING: Rehabilitative Center, Italy. SUBJECTS: 29 individuals with a motor complete SCI (American Spinal Injury Association impairment scale grade A or B) and 22 controls. METHODS: According to the modified Ashworth scale (MAS), patients were subgrouped as SCI-1 (MAS=1, 1+) and SCI-2 (MAS=2, 3). Passive flexo-extensions of the knee were applied using an isokinetic device (LIDO Active) at 30°, 60°, 90° and 120° s(-1). We measured the peak torque, mean torque (MT) and work. Simultaneous electromyography (EMG) was recorded from leg muscles. RESULTS: At the speed of 120° s(-1) all SCI-2 patients presented EMG reflex activities in the hamstring muscle. All biomechanical parameter values increased significantly according to speed, but analysis of variance revealed a significant interaction between the angular velocity and group (F(d.f. 6, 138) = 8.89, P < 0.0001); post hoc analysis showed significantly greater torque parameter values in the SCI-2 group compared with the SCI-1 group and the control group at 90° and 120° s(-1). Receiver operating characteristic curves showed that using peak torque values the probability of correctly classifying a patient into SCI-1 and SCI-2 was 95%, compared with 70% for MT and 68% for work. CONCLUSIONS: The isokinetic device is useful for distinguishing individuals with a high level of spastic hypertonus. Examination of EMG activity may help ascertain whether increased muscle tone is caused by reflex hyper excitability and to determine whether muscle spasm is present. Peak torque and simultaneous EMG assessment should be considered for the evaluation of individuals with SCI in the rehabilitative context, that is, in measuring therapeutic interventions.

Abnormal projection of corticospinal tracts in a patient with congenital mirror movements.

A 31 year-old woman with familial congenital mirror movements not associated with other neurological defects underwent a detailed neurophysiological evaluation including: voluntary electromyographic activity recorded from upper limbs in response to acoustic stimuli, motor evoked potentials from the thenar muscles to focal transcranial magnetic stimulation, F waves from upper extremities, scalp somatosensory evoked potentials and long-latency responses from thenar muscles to electric stimulation of the median nerve. The results were consistent with the presence of fast-conducting pathways connecting each hand motor cortex with both contra- and ipsilateral spinal motoneurones.

Monitoring of somatosensory evoked potentials during carotid endarterectomy.

Somatosensory evoked potentials (SEPs) were monitored in the course of 368 carotid endarterectomies (CEAs) carried out in 312 patients. In an initial group of 26 patients the shunt was used routinely while in a second group, involving 342 CEAs, it was applied selectively on the basis of modifications which the SEP underwent during clamping. The criterion for shunting was the progressive reduction, up to 50%, of the N20-P25 amplitude. New postoperative neurological deficits appeared in 6 patients, all of whom displayed a transitory SEP flattening. The SEPs of 2 of these returned to normal by the time they awoke and both showed a clinical deficit homolateral to the operated side. In only 2 cases did the deficit fail to regress completely and their postoperative CT scans revealed ischaemic lesions. A positive relationship emerged between SEP changes and back pressure values; nonetheless, as many as 75% of the patients with low residual back pressure values (less than 25 mmHg) tolerated the clamping. SEP monitoring appears to provide a reliable basis for selectively applying a shunt when there is a high risk of haemodynamic ischaemia during clamping.

Transmission times from cutaneous and mixed nerves of lower limbs.

In each of 10 normal subjects, P28 and N31 far-field components as well as the cortical N37 and P40 waves were identified for both Sural (SN) and Posterior Tibial nerve (PTN) stimulation at the ankle. Peripheral conduction velocity along the popliteal fossa-L3 segment and spinal transmission velocity over the L3-Cv2 segment did not differ significantly for the two nerves. The average latencies of N37 and P40 to stimulation of PTN were 2.55 and 3.65 msec shorter than corresponding latencies from SN. If we consider the P28-N37 and P28-P40 intervals as central transmission times, only the former approaches upper limb CCT values closely enough to support the analogy between median nerve N20 and PTN N37. At the intracranial level, the P28-N37 inter-peak latency was significantly shorter for PTN than SN. The P28 component is generally attributed to lemniscal activity. Thus, the discrepancy in afferent transmission times from the leg's mixed and sensory nerves would appear to take place at a level that is supralemniscal but subcortical.

Long-term nervous system damage from radiation of the spinal cord: an electrophysiological study.

A group of 13 patients suffering from Hodgkin's disease who had undergone chemotherapy and radiotherapy (above and below the diaphragm) approximately 10 years earlier was studied. The total chemotherapeutic dose was similar for all patients; the radiotherapy dose, however, was standard for 7 patients, while the other 6 received much higher dosages over limited regions of the spinal cord. Although most of these patients appeared normal both clinically and on magnetic resonance imaging, a neurophysiological study was performed to determine whether there was any involvement of the central or peripheral nervous system. Motor conduction velocity and sensory conduction velocity were measured in the lower limbs as well as spinal- and scalp-recorded somatosensory evoked potentials (SEPs) in response to stimulation of the posterior tibial and sural nerves at the ankle. In addition, motor evoked potentials were recorded from the upper and lower limbs during cortical stimulation. All neurophysiological data were normal in patients who had received a standard radiation dose, while most of those who had been exposed to higher doses showed altered cortical SEPs and a slowing of central conduction time (D10-P1). Thus even though they were asymptomatic, these patients appeared to have sustained CNS damage, mainly at the level of the spinal cord.

Anesthetic induction with thiopental: its effect on scalp topography of median nerve somatosensory evoked potentials.

The effects on median nerve somatosensory evoked potentials (SEPs) of analgesic doses of fentanyl, meperidine or morphine and of sodium thiopental (STP) anesthesia (4 mg/kg) were tested in 36 surgical patients. We also explored changes in SEP components as a function of their scalp location. Before and after medication, responses were recorded from the scalp overlying the parietal cortex (ipsi- and contralateral to the stimulated arm) and the precentral (contralateral) cortex. None of the three opiates affected SEP latencies or amplitudes. The barbiturate increased the amplitudes of subcortical and early cortical components (N18, N20, P22, P25), whose latencies, however, were not significantly modified. The effect of STP on later SEP cortical components depended on their scalp topography: parietal N33 and P45 underwent significant changes in both latency and amplitude, whereas precentral N30 showed a significant amplitude increase only. Thiopental anesthesia produces clearer short-latency SEP recordings, from both parietal (components N20-P25) and precentral (P22, N30) areas.

Neurological damage in patients irradiated twice on the spinal cord: a morphologic and electrophysiological study.

We reviewed the files of 950 patients treated for Hodgkin's disease since 1966 and were able to find five patients treated with radiochemotherapy and irradiated twice on volumes including a cord segment, at various time intervals, and surviving until now. Seven patients with comparable clinical and therapeutic features, but not reirradiated on the cord, were chosen as a control group and were examined with the same diagnostic procedures. The cumulative cord dose in the reirradiated patients was recalculated and ranged from 50 to 70 Gy. All these patients and the control cases were followed up for more than 10 years and presented no or only minor neurological symptoms. We compare the results of both magnetic resonance imaging (MRI) and electrophysiological studies (spinal and scalp recorded somatosensory evoked potentials--SEPs) in an attempt to define the characteristics of the subclinical damage present in these patients. While no cord abnormality was demonstrated with MRI, electrophysiological studies evidenced a clear difference between cases and controls, as far as the D10-P1 conduction time and SEPs average amplitude are concerned. Advantages and drawbacks of a wider use of electrophysiological methods in research work on cord radiation damage are presented, along with the possible implications of the results obtained for the understanding of the pathogenesis and of the dose dependence of radiation myelitis (RM).

Lack of efficacy of phosphatidylcholine in ataxias.

We gave phosphatidylcholine orally at a daily dosage of 9 grams for 4 years to 20 subjects with Friedreich's ataxia (FA) and 24 with olivopontocerebellar atrophy (OPCA). There was no clinical improvement during the follow-up compared with 12 ataxic patients (six FA and six OPCA) who did not receive any treatment. A 6-month trial at a double dose did not have any significant effect. This study indicates that phosphatidylcholine does not change the natural course of ataxias.

Visual involvement in Friedreich's ataxia: PERG and VEP study.

Neuro-ophthalmological assessment, including red-free light retinography, in conjunction with simultaneous visual evoked potential (VEP) and pattern electroretinogram (PERG) recordings were performed in 10 Friedreich's ataxia patients: 9 patients showed marked VEP abnormalities. Moderate PERG amplitude reduction, with normal latencies, was related to mild and scattered fiber loss revealed by red-free light retinography. The initial part of the visual pathways does not seem to be the main site of electrophysiological abnormalities as demonstrated by the greater extent and relative independence of VEP versus PERG alterations. Primary axonal degeneration of the optic nerve and tracts cannot account for all features of VEP abnormalities, thus implying some dysfunction in succeeding visual structures as well.

Electrophysiological studies of the visual system in myotonic dystrophy.

Ocular signs and electroretinal alterations frequently occur in Myotonic Dystrophy (MD). Surprisingly few reports describe VEP abnormalities for this syndrome. Since the evaluation of cortical visual responses is linked to an understanding of preceding retinal changes, we conducted a systematic study of the visual system including ophthalmological and electrophysiological (EOG, ERG, PERG, VEP) investigation in 14 confirmed myotonic patients. The various tests revealed consistent abnormalities, the most frequent of these being PERG and VEP changes. These alterations seemed to occur independently of one another, suggesting impaired function at different levels of visual pathway. A generalized defect of cell membrane has recently been proposed as etiopathogenesis of typical EMG and systemic features of the disease. Such membrane dysfunction might account for the early and marked abnormalities in electrophysiological tests, even in the absence of neuro-ophthalmological changes.

Selective shunting based on somatosensory evoked potential monitoring during carotid endarterectomy.

Somatosensory Evoked Potentials (SEPs), to median nerve stimulation, were continuously monitored in 58 patients undergoing carotid endarterectomy A first group of patients was shunted routinely; in a second group the shunt was selectively applied when inadequacy of collateral circulation was suspected based on stump pressure values and SEP changes. Both amplitude and latency modifications of SEPs occurred during surgery; however no post-operative neurological deficit was seen unless there was a complete flattening of cortical waves, even a transitory one. Inadequate collateral circulation and embolic ischemia affected SEPs differently. While the latter produced a disappearance of all cortical waves, the former led first to a progressive flattening of later cortical waves and then of N20 as well. For values of stump pressure ranging between 20 and 50 mmHg SEPs were unchanged in some patients and altered in others. These findings may explain the controversies existing about the usefulness of stump pressure for predicting tolerance to carotid clamping.

Auditory and somatosensory evoked potentials (AEPs and SEPs) and ballistic movements in Parkinson disease.

In five patients with initial idiopathic Parkinson disease AEPs (early and late components of auditory evoked potentials), SEPs (somatosensory evoked potentials) and arm ballistic movements (abduction of the humerus) were studied. Experimental sessions were conducted before starting treatment (L-Dopa plus Carbidopa) and at two and six month intervals. Before treatment evoked potential abnormalities were found in four out of five patients; EMG patterns underlying ballistic arm abduction movements were altered in all patients; corresponding prolonged duration of initial movements and low mean velocities were found. After treatment AEP and SEP showed a reduction of previously observed abnormalities and both EMG patterns and kinematic variables consistently improved. It is suggested that the electrophysiological investigations employed in this preliminary study may be a useful tool in clinical and pharmacological researches on Parkinson disease.

Pseudoperiodic paroxysmal discharge in a case of hemorrhagic shock.

We report a case of hemorrhagic shock associated with an EEG pattern resembling pseudoperiodic lateralized paroxysmal discharges, repeated focal motor seizures on the opposite side of the prevalent EEG abnormalities and consciousness disturbances in the absence of a demonstrable cerebral lesion occurring in a 45 year-old woman without a personal or familial history of epilepsy. This unusual electroclinical picture appeared inexplicably several days after the hemorrhagic shock when the laboratory data had already normalized. The only cause of this picture seemed to be brain hypoxia and the metabolic disorders consequent upon hemorrhagic shock.

Auditory evoked potentials (early, middle, late components) and audiological tests in Friedreich's ataxia.

A functional assessment of the acoustic pathways in a group of 9 patients with Friedreich's ataxia was performed. In none of them was symptomatic auditory impairment noticeable. All patients were submitted to audiological tests and AEP recording. AEPs included early (BAEPs), middle (MLCs) and long (LLCs) latency components. The absence of one or more BAEP waves was observed in 5 out of 9 patients. N85 latency was significantly increased in all but one patient. MLCs, particularly P12, N15, P25 were often normal in amplitude and latency, scarcely showing a positive relationship with abnormalities of preceding and following waves. Pure tone audiometry revealed cochlear or neural impairment only in 2 patients. Speech audiometry showed deficits in all patients. These investigations, taken as a whole, showed a prevalent involvement of the brain-stem acoustic pathways, presumably at different levels, seldom associated with eighth nerve impairment. In some cases LLC (N85) abnormalities could not be interpreted as a consequence of impaired function in peripheral and brain-stem acoustic sites and might suggest a cortical dysfunction. Major BAEP abnormalities were observed in patients with longer disease duration, while N85 changes were unrelated to the duration and the severity of the illness. The former may prove to be a reliable means of monitoring the progression of the disease, the latter could be employed as a complementary procedure in its early diagnosis.

[Electrophysiologic studies (auditory and somatosensory evoked potentials) in Friedreich's ataxia]. / Indagini elettrofisiologiche (potenziali evocati acustici e somestesici) nell'atassia di Friedreich.

Auditory and somatosensory evoked potentials were recorded from 10 patients suffering from Friedreich's ataxia. All patients were subjected to audiological tests and EMG-ENG study. Acoustic evoked potentials recordings included brainstem acoustic evoked potentials and long latency components. Peripheral and central components of somatosensory evoked potentials were obtained by stimulating the median nerve at the wrist and elbow. Various abnormalities of the cortical components were observed in all patients for both acoustic and somatosensory evoked potentials. Analysis of brainstem acoustic evoked potentials and of the early components of somatosensory evoked potentials showed a different incidence of abnormalities. The main feature of brainstem acoustic evoked potential changes was the frequent absence of one or more waves; the greatest abnormalities occurred in patients whose disease was of long duration. Long latency components (N85) were significantly prolonged in all but one patient. There was often an absence or reduction of early somatosensory evoked potentials with normal or near normal latencies, even though cortical responses were markedly prolonged. The sensory conduction velocity between stimulation sites at wrist and elbow was normal in all patients. Clinically brainstem acoustic evoked potentials may prove to be a reliable means of monitoring the progression of the disease, while long latency components and somatosensory evoked potentials could be used as complementary procedures in early diagnosis.