[Evoked acoustic responses in the brain stem of subjects with facial hemispasm and megabasilar anomaly]. / Risposte evocate acustiche del tronco encefalico in soggetti con emispasmo facciale e con megabasilare.

We examined 8 subjects affected by hemifacial spasm. The CT exam showed a megadolichobasilaris vessel in five of them. Four of these five presented BAEP anomalies. Three of these four showed a decreased amplitude of the V wave and the other one a pathological increment of the I-V interval.

[Pre-, intra- and postoperative somatosensory evoked potentials in cervical vertebral and spinal cord injuries]. / Potenziali evocati somatosensoriali pre-, intra- e postoperatori nei traumi vertebro-midollari cervicali.

Somatosensory Evoked Potentials (SEPs) to upper limb nerves stimulation, are able to detect cervical medullary dysfunction in case of cervical spine trauma. We have monitored cervical spinal cord functionality in 13 subjects with severe cervical spine trauma. In most of subjects, a prolonged P11onset-P13onset interval was found. Postoperatory a reduced P11onset-P13onset interval well correlates with clinical improving of medullary function. Intraoperatory, a transitory impairment of spinal cord function was found during medullary distraction and vertebral body fusion.

Comparison of cervical SEPs on median, radial and ulnar nerve stimulation.

Cervical responses (SEPs) to stimulation of the median, radial and ulnar nerves were studied in 9 healthy subjects. In recordings from e Cv7 electrode referenced to a scalp electrode P11 presented a bilobed (P11a + P11b) profile for all three nerves whereas from Cv2 only P11b appeared as a rule. P11a and P11b were more distinct in the ulnar than in the median and radial nerves. The P11 onset-P13 onset interval was virtually the same for the radial and median nerves and approximately 0.4 msec longer for the ulnar nerve. This difference probably represents the Cv8 to Cv6 intramedullary conduction time. An exact evaluation of P11 onset is possible only in low cervical recordings, though the P11 peak may be a useful landmark when recording from Cv2. P11a would appear to originate at (or near) spinal entry, P11b high in the cervical cord and P13 at supraspinal level.