Realizzazione di una normativa per la registrazione dei Potenziali Evocati Miogenici Vestibolari (VEMPs) con Amplaid MK22

The term VEMPs (Vestibular Evoked Myogenic Potentials) means a muscular potential evoked at the sternocleidomastoideus muscle (SCM) following an intense acoustic stimulation, through the activation of vestibular receptor structures. This is called vestibulocollic reflex. It is believed that the Vemps are due to a disynaptic reflex arc that consists of otolitic receptors, saccular mainly, vestibular nuclei (1st synapse), spinal motoneurons (2nd synapse) and the SCM. These potentials, recorded as undulatory fluctuations compared to the isoelettric signal, are characterized by a biphasic complex called p1-n1 (or p13-N23) that appears within 30 ms from stimulus. The presence of this complex indicates the integrity of the reflex, especially of the lower branch of the vestibular nerve. Currently the only parameter on which to rely in vestibular diagnostics are the p1 and n1 latencies with the presence/absence of the potential. Other waves have been identified as the p2-n2 (or p34-N44) that probably derive from cochlear afferences, but these being so fickle these are useless. The purpose of our experiment was to obtain normative reference values for the apparatus responsible for the registration of these potentials at the Operative Unit of Audiology of Ferrara, in this case it is an Amplaid MK22 commonly used in recording evoked potentials. The p1-n1 complex was examined in 50 normally-hearing volunteer adults aged between 19 and 32 years (average 23.4), with stapedial reflexes present bilaterally and without history of dizziness. The acoustic stimulus used was a 500 Hz logon with a duration of 10 msec, with a repetition frequency of 4/sec and with an intensity of 130 dB SPL presented monaural or binaural via air conduction. The term VEMPs (Vestibular Evoked Myogenic Potentials) means a muscular potential evoked at the sternocleidomastoideus muscle (SCM) following an intense acoustic stimulation, through the activation of vestibular receptor structures. This is called vestibulocollic reflex. It is believed that the Vemps are due to a disynaptic reflex arc that consists of otolitic receptors, saccular mainly, vestibular nuclei (1st synapse), spinal motoneurons (2nd synapse) and the SCM. These potentials, recorded as undulatory fluctuations compared to the isoelettric signal, are characterized by a biphasic complex called p1-n1 (or p13-N23) that appears within 30 ms from stimulus. The presence of this complex indicates the integrity of the reflex, especially of the lower branch of the vestibular nerve. Currently the only parameter on which to rely in vestibular diagnostics are the p1 and n1 latencies with the presence/absence of the potential. Other waves have been identified as the p2-n2 (or p34-N44) that probably derive from cochlear afferences, but these being so fickle these are useless. The purpose of our experiment was to obtain normative reference values for the apparatus responsible for the registration of these potentials at the Operative Unit of Audiology of Ferrara, in this case it is an Amplaid MK22 commonly used in recording evoked potentials. The p1-n1 complex was examined in 50 normally-hearing volunteer adults aged between 19 and 32 years (average 23.4), with stapedial reflexes present bilaterally and without history of dizziness. The acoustic stimulus used was a 500 Hz logon with a duration of 10 msec, with a repetition frequency of 4/sec and with an intensity of 130 dB SPL presented monaural or binaural via air conduction. The term VEMPs (Vestibular Evoked Myogenic Potentials) means a muscular potential evoked at the sternocleidomastoideus muscle (SCM) following an intense acoustic stimulation, through the activation of vestibular receptor structures. This is called vestibulocollic reflex. It is believed that the Vemps are due to a disynaptic reflex arc that consists of otolitic receptors, saccular mainly, vestibular nuclei (1st synapse), spinal motoneurons (2nd synapse) and the SCM. These potentials, recorded as undulatory fluctuations compared to the isoelettric signal, are characterized by a biphasic complex called p1-n1 (or p13-N23) that appears within 30 ms from stimulus. The presence of this complex indicates the integrity of the reflex, especially of the lower branch of the vestibular nerve. Currently the only parameter on which to rely in vestibular diagnostics are the p1 and n1 latencies with the presence/absence of the potential. Other waves have been identified as the p2-n2 (or p34-N44) that probably derive from cochlear afferences, but these being so fickle these are useless. The purpose of our experiment was to obtain normative reference values for the apparatus responsible for the registration of these potentials at the Operative Unit of Audiology of Ferrara, in this case it is an Amplaid MK22 commonly used in recording evoked potentials. The p1-n1 complex was examined in 50 normally-hearing volunteer adults aged between 19 and 32 years (average 23.4), with stapedial reflexes present bilaterally and without history of dizziness. The acoustic stimulus used was a 500 Hz logon with a duration of 10 msec, with a repetition frequency of 4/sec and with an intensity of 130 dB SPL presented monaural or binaural via air conduction. The results showed the costant presence of the complex p1-n1 while the complex p2-n2 is present only in a small percentage of subjects. The p1 and n1 latencies and the p1-n1 complex width reproduce faithfully in the same subject, while there is a more obvious interindividual difference regarding the p1-n1 width than for the p1 and n1 latencies.