Nasopharyngeal electrode recording of somatosensory evoked potentials as an indicator in brain death.

Median nerve somatosensory evoked potentials were recorded in 28 comatose patients, eight of whom were progressing from coma to eventual brain death and in 11 brain dead patients using electrodes over the scalp, neck and nasopharynx (nasopharyngeal electrode). This recording technique was used to assess the different derivation of brainstem P14 wave activity. It showed that in the midfrontal scalp to the nasopharynx derivation a clear P14 was present in all comatose patients. This component disappeared during the passage from coma to brain death. In a separate group, simultaneous direct recordings in the vicinity of the dorsal column nuclei and with a nasopharyngeal electrode were made in five patients undergoing neurosurgical procedures at the craniocervical junction with the same somatosensory evoked potential monitor. We found that the P14 recorded with the nasopharyngeal electrode in the neurosurgical patients corresponded in latency and morphology with the P14 recorded directly on the surface of the craniocervical junction and more specifically in the vicinity of the nucleus cuneatus. The nasopharyngeal electrode provides non-invasive access to the ventral brainstem at the medullo-pontine level and the disappearance of the P14 shows a clear sign of involvement of the craniocervical junction in brain dead patients. Our study showed that with a simple montage the nasopharyngeal electrode is an effective non-invasive monitor for brainstem activity and can be used as an early diagnostic indicator of brainstem death.

Elsberg syndrome: radiculomyelopathy and acute urinary retention in patient with genital herpes.

We describe a case of a sexually active woman who presented acute urinary retention associated with herpes genitalis infection and with few other neurological signs. The outcome of the disease was positive. We stress the utility of a careful CSF examination.

[The effect of propofol on somatosensory potentials evoked by stimulation of the lower limbs]. / L'effeto del propofol sui potenziali evocati somatosensoriali da stimolazione degli arti inferiori.

The Authors point out that during anaesthesia with propofol, latencies of early cortical waves after SEP of the posterior tibial nerve do not suffer significant variations: this may turn out to be useful during intraoperative monitoring when having to watch the integrity of nervous structures of spinal cords undergoing handling or possible indirect damage.

[Somatosensory evoked potentials after stimulation of the posterior tibial nerve in multiple sclerosis: comparative analysis with other modalities of evoked response and magnetic resonance]. / I potenziali evocati somatosensoriali da stimolazione del nervo tibiale posteriore nella sclerosi multipla: analisi comparativa con le altre modalità delle risposte evocate e la risonanza magnetica.

Electrophysiological tests have proved to be a valuable method in assessing multiple sclerosis (MS) patients. In the last few years, scalp recorded short latency somatosensory evoked potentials to stimulation of nerves in the "lower extremity" have been more and more extensively employed. Some studies have aimed at comparing the sensitivity of MR imaging and multimodality evoked potentials, with somewhat conflicting results. In the present study posterior tibial nerve somatosensory evoked potentials (ptnSEPs) were performed in 29 MS patients with the aim to investigate the ability in revealing spinal cord conduction abnormalities and the sensitivity towards other evoked potentials and MR in MS. ptnSEPs showed a high percentage of abnormalities which did not significantly differ from that of visual evoked potentials; moreover in conjunction with median nerve SEPs can be used to localize thoracic or lumbar cord demielinating lesions, not evidenced on MR imaging. These results confirm that ptnSEPs, although non specific and crude in terms of precise localization, are a sensitive tool in detecting lesions, even subclinical, in MS patients. Moreover in anatomic regions like spinal cord where MR imaging is not very sensitive because the lower signal-to-noise ratio, they represent the only method available for demonstrating lesions.