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H Hafner

Publications and source records attributed to H Hafner.

33 records · Page 2Linked to original sources
PubMed1994

Intra- and extra-uterine development of neonatal 3-channel Lissajous' trajectory of auditory brainstem evoked potentials.

This study compared intra- and extra-uterine maturation of the auditory pathway, using auditory brainstem evoked potentials (ABEPs), recorded with three orthogonal differential electrode configurations. From the three records of each subject, 3-channel Lissajous' trajectories (3CLTs) were derived and analyzed. 107 newborns were compared at the same gestational and post-conceptional (gestational+postnatal) age, from 29 weeks (wks) up to 43 wks. In addition, we explored the effects and neurophysiological consequences of early exposure to extra-uterine life, on the peripheral and central portions of the auditory pathway. Our findings indicate that exposure of premature infants to the extra-uterine environment is associated with advanced peripheral development, but slower central conduction compared to intra-uterine development.

Analysis of Variance↗
PubMed1993

A physiological coma scale: grading of coma by combined use of brain-stem trigeminal and auditory evoked potentials and the Glasgow Coma Scale.

Forty-five comatose patients were prospectively studied by means of clinical examination and evoked potentials. In each patient, clinical data included Glasgow Coma Scale (GCS) score, age, pupillary response to light, corneal reflex, and eye movements. Neurophysiological evaluation was based on brain-stem trigeminal evoked potentials (BTEPs) and brain-stem auditory evoked potentials (BAEPs). For each physiological test, a progressive grading system was designed. This system was based on the evaluation of central conduction times along the trigeminal and the auditory pathways within the brain-stem. The accuracy of the clinical and the neurophysiological indicants in predicting "favorable" or "unfavorable" outcome was assessed singly and in combination. Of the clinical indicants, the GCS provided the most accurate prognosis (80%). Similar results were provided by the BAEP and the BTEP, with significant improvement in the confidence of outcome prediction. No significant difference in the accuracy of outcome predictions could be found between combined clinical data and neurophysiological data. However, the combination of clinical and neurophysiological data markedly increased both the accuracy and the confidence of outcome prediction, reaching 86% correct predictions at the over 90% confidence level with only 2% false pessimistic errors. According to these findings, a clinical-physiological coma scale, the trigeminal-auditory Glasgow (Coma Scale) score (TAG score) was designed. The TAG score demonstrated the highest accuracy at each confidence level as compared to other single indicants. We concluded that the TAG score may improve the evaluation of deep comatose patients and assist the physician in the management of such patients.

Adolescent↗
PubMed1993

Critical ages in brainstem development revealed by neonatal 3-channel Lissajous' trajectory of auditory brainstem evoked potentials.

Auditory brainstem evoked potentials (ABEPs) were recorded from 91 newborns from 7 age groups between 26 to 43 weeks of gestation. In addition to the widely used vertex-mastoid derivation, potentials were recorded from three orthogonal electrode configurations, and represented in 3 dimensional voltage-space as three-channel Lissajous' trajectories (3CLTs). ABEPs were evoked by alternating polarity, monaural 75 dBnHL clicks presented at rates of 10/s, 55/s and 80/s. Potentials were also recorded to 45 dBnHL and 15 dBnHL clicks presented at 10/s. 3CLT point by point (apex latencies, amplitudes and orientation) as well as planar segment (planar segment position and duration) descriptors, along with peak latencies of the vertex-mastoid peaks, were followed for effects of age, stimulus intensity and rate. ABEPs began to appear consistently at 29 weeks of gestation to high stimulus intensities, with a rapid decrease of ABEP thresholds up to 34 weeks. At 35 weeks, thresholds stabilized approximately at adult values. The results indicate a significant effect of stimulus rate and intensity as well as of gestational age group on apex latencies. The findings also showed changes in apex orientations associated with stimulus rate and intensity interacting with gestational age. 3CLT descriptors enhanced the understanding of these results in relation to developmental and maturational aspects of the auditory system. The results may be explained by maturational change in relative contributions of constituents of the complex ABEP generators.

Analysis of Variance↗
PubMed1991

Development of auditory brainstem evoked potentials in newborn infants: a three-channel Lissajous' trajectory study.

Auditory brainstem evoked potentials (ABEP) were recorded from 50 newborns (35-43 weeks gestational age), using three orthogonal differential electrode pairs, in addition to the widely used vertex-mastoid derivation. Potentials were evoked by alternating polarity, 75 dBnHL clicks presented monaurally at a rate of 10/s. From the records of the three orthogonal electrode pairs (nasion-inion; vertex-spinous cervical process VII; left-right mastoids), Three-channel Lissajous' trajectories (3CLT) were derived and analyzed. 3CLT point-by-point, as well as segmental descriptors were compared with peak latencies of the vertex-mastoid derivation. Point-by-point 3CLT descriptors included apex amplitude, latency and orientation. Segmental descriptors included planar segment beginning latencies, duration and orientation. The interpretation of these results in relation to developmental aspects of the auditory system, as well as to the question of ABEP generators, is enhanced by using 3CLT descriptors of ABEP, which are more comprehensive than their single-channel counterparts. 3CLT apices correlated well with the Vertex-Mastoid defined peaks. Both peak and apex latency changes indicate that at the developmental stages surveyed in this study, development takes place in the more central portions of the pathway, whereas the peripheral portion is already relatively mature. The results also indicate a maturational change in the relative contributions of constituent generators of ABEP components.

Brain Stem↗
PubMed1986

Auditory brainstem evoked potentials in evaluating the central effects of middle ear effusion.

Auditory brainstem evoked potentials (ABEP) were recorded to determine whether children who suffered in the past, or suffered at time of examination from Secretory otitis media (S.O.M.), exhibited slowed conduction along their auditory brainstem. Five groups of subjects were examined: children with active S.O.M. during the examination, children with S.O.M. in the past who were treated non-surgically and recovered, children with S.O.M. in the past who were treated surgically and recovered, children who were treated by insertion of ventilating tubes (V.T.), and had S.O.M. during the examination (recurrent S.O.M.), and a control group of neurologically and audiologically normal, age-matched children with no history of S.O.M. 205 ears were tested in all. Each of the groups was subdivided according to the severity of hearing loss, duration and type of treatment. These parameters were evaluated within and between groups, and in relation to the control group. Significant increases of interpeak latency differences (IPLD) between peaks V and III as well as V to I were found in the S.O.M. groups compared to the control group. The duration of the disease was found to be the dominant factor slowing central conduction. These findings confirm the suggestion that attenuation in auditory stimulation at an early age affects central conduction.

Audiometry, Evoked Response↗
PubMed1986

Auditory brainstem evoked potentials in evaluating the efficacy of surgical ventilation of the middle ear.

Conductive hearing loss in children is most commonly associated with Secretory otitis media (S.O.M.). Since auditory brainstem evoked potentials (ABEP) reflect conductive damage in prolonged peak latencies, the present study evaluated the efficacy of surgery for ventilating the middle ear, by comparing changes in peak latencies. These changes were compared in 4 groups of children (4-12 years old): children with S.O.M. in the past, who recovered as a result of conservative treatment; children with S.O.M. in the past, who had been operated on with insertion of ventilation tubes (V.T.); children with S.O.M. in the past, who had been operated on and who still had V.T. at the time of study, and a control group with healthy ears. In all, 183 ears were tested. The results indicate that there is no significant audiometric and electrophysiological difference between the groups who recovered with or without V.T.

Audiometry, Evoked Response↗
PubMedDate not supplied

Short latency trigeminal evoked potentials: normative data and clinical correlations.

A very short latency trigeminal evoked potential (STEP) to electrical stimulation of the upper lip has been recorded from over the scalp. This potential consists of 5 distinct peaks within the 12 msec range. Normative data were obtained from 25 healthy volunteers. The impact of the stimulus rate and intensity on the response was studied in each subject. These results were compared to those of 19 patients suffering from lesions involving the trigeminal system in its peripheral aspect or the brain-stem. The STEP was consistently abnormal whenever the involved side was stimulated. Changes in peak latencies and in interpeak latency differences (IPLD) correlated well with clinical and radiological findings and improved with the removal of the offending lesion. The STEP proved to be a reliable method for evaluating the trigeminal system in its peripheral and central pathways; it may thus serve as an additional parameter for studying brain-stem functions.

Adolescent↗
PubMedDate not supplied

Monitoring of brain-stem trigeminal evoked potentials. Clinical applications in posterior fossa surgery.

Brain-stem trigeminal evoked potentials (BTEPs) were monitored intraoperatively in 17 patients during posterior fossa surgery. Satisfactory BTEP recording was performed in all patients without technical problems or interfering with the activity of the operating team. The BTEP was not altered by anesthetic agents or muscle relaxants. Intraoperative monitoring of the BTEP showed wave form alterations or increasing peak latencies in 10 patients. Among these patients, the BTEP demonstrated a dynamic correlation with the surgical process in 8 instances. Two major causative surgical manipulations were identified: cerebellar retraction in 4 cases and tumor dissection from the brain-stem in 6 cases. Withholding the dissection of the tumor, readjusting a cerebellar retractor or further modifying the surgical attitude resulted in partial or complete return of the wave form in 7 patients. The BTEP at the end of surgery proved to correlate with the immediate surgical outcome in most instances. We concluded that the intraoperative monitoring of the BTEP was feasible and suggested, despite the small number of patients, a potential value in the survey of brain-stem functions during posterior fossa surgery.

Adult↗
PubMedDate not supplied

Trigeminal and auditory evoked responses in minor head injuries and post-concussion syndrome.

Forty patients who sustained minor head trauma were investigated by brainstem trigeminal and auditory evoked potentials (BTEP, BAEP) and middle-latency auditory evoked potentials (MLAEP). The patients were evaluated within the first 48 h following their admission and at 3 months after the injury. Outcome was scored at the follow-up examination according to six complaints: failure to resume previous professional activity, headache, memory disorders, dizziness and vertigo, behavioural and emotional disturbances, and other symptoms of a neurological nature. Post-concussion syndrome (PCS) was defined by the presence of four or more of the listed features. All three evoked potential modalities showed significantly increased latencies at the initial assessment, disclosing disseminated axonal damage. Unlike the BTEPs and the BAEPs, the MLAEPs proved to correlate to outcome at 3 months, especially in its psychocognitive aspects. These findings suggest that organic diencephalic-paraventricular primary damage may account for the occurrence of PCS.

Adolescent↗