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.

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.

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.

[Electrophysiologic studies (auditory and somatosensory evoked potentials) in Friedreich's ataxia]

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.

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.

[Neurophysiological (evoked auditory and somatosensory potentials) and neuroradiological (cranial CT) study in patients with olivopontocerebellar atrophy]

Thirteen patients affected by either dominant or recessive and/or sporadic olivopontocerebellar atrophy were studied. All patients were subjected to auditory evoked potential recordings including early and long latency components, CT scans, vestibular and EMG-ENG examinations. In nine patients somatosensory evoked potentials were also recorded. Clear-cut abnormalities in brainstem auditory evoked potentials were observed in only two patients while a slight reduction of the IV-V/I amplitude ratio was found in seven cases. N85 was increased in two patients. The main feature of somatosensory evoked potentials abnormalities was a delayed N20 in association with prolonged N13-N20 central conduction time (five patients). For all patients the CT scan varying degrees of cerebellar and brainstem atrophy. There was no clear correlation between the abnormalities revealed by neurophysiological and neuroradiological investigations and the severity and duration of the illness. It is noteworthy that auditory and/or somatosensory evoked potential changes were found in all dominant olivopontocerebellar atrophy patients.

Gynecomastia in epileptics treated with phenobarbital, phenytoin and fluoresone: two case reports

Gynecomastia developed in two epileptic patients some months after the addition of oral fluoresone 750 mg daily to the phenobarbital and phenytoin already being administered. The common systemic diseases that may give rise to gynecomastia were excluded. One of the patients presented hyperprolactinemia and a raised estrogen/androgen ratio but the hormone levels were not raised in the other. The onset of symptoms after fluorescence in both cases is highly suggestive, although the pathogenetic mechanism is not clear.

[Continuous partial epilepsy in a case of cerebral abscess of long duration]

A patient affected by continuous clonus of the right half of his tongue and face with dysphasia and right hemiparesis is described. Partial continuous epilepsy of Kojewnikow was diagnosed. The CT scan showed a spreading lesion surrounded by intense oedema in the left central region, as well as a longstanding subdural hematoma complicated by osteitis. This finding lead to a diagnosis of cerebral abscess which was confirmed by surgery. In this paper it is also analyzed the cortical and/or subcortical origin of this peculiar type of epilepsia.