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Biomedical subjects

M B Møller

Publications and source records attributed to M B Møller.

At least 19 recordsLinked to original sources
PubMed1992

Compound action potentials recorded from the exposed eighth nerve in patients with intractable tinnitus.

Compound action potentials (CAP) were recorded directly from the exposed intracranial portion of the eighth nerve in 19 patients undergoing microvascular decompression (MVD) of the eighth nerve for intractable tinnitus. The waveform of the CAPs recorded in patients with tinnitus varied from normal to highly abnormal, but only in 1 patient were there distinct abnormalities in the waveform of the CAP that could not be attributed to the patient's hearing loss. The mean values of the latencies of the N1 and N2 peaks in the CAPs recorded from the exposed eighth nerve in patients with tinnitus and high-frequency hearing loss were virtually indistinguishable from the latencies obtained in patients with similar hearing loss but no tinnitus. There was no statistically significant difference between the latency of peak III in the brainstem auditory evoked potentials (BAEPs) in these two groups of patients, but the latency of peak V was slightly shorter (statistically significant) in the patients with tinnitus than it was in the patients without tinnitus.

Action Potentials↗
PubMed1992

Some forms of tinnitus may involve the extralemniscal auditory pathway.

It has previously been shown that the click-evoked responses recorded from the intracranial portion of the eighth nerve in patients with incapacitating tinnitus are not abnormal, nor is the latency of peak III of the click-evoked brainstem auditory-evoked potentials significantly altered; however, the latency of peak V is slightly (but significantly) shortened in comparison to that of patients with the same degree of hearing loss but no tinnitus. In this study the hypothesis that the extralemniscal auditory system is involved in the generation of tinnitus is tested. We made use of the fact that neurons of the extralemniscal auditory system also receive input from the somatosensory system, and that stimulation of the somatosensory system can influence the processing of auditory information in the extralemniscal system. In 4 of 26 patients with mild-to-severe tinnitus whose median nerve was stimulated electrically, the tinnitus increased noticeably during stimulation, in 6 the intensity of the tinnitus decreased noticeably, and in the remaining 16 there was no noticeable change in the tinnitus. In some of the patients the character of the tinnitus changed in a complex way. There were no significant differences in hearing thresholds in these three groups of patients. Electrical stimulation of the median nerve in 12 individuals with normal hearing who did not have tinnitus either had no effect on the loudness of sounds or it caused a slight increase in the loudness.

Auditory Pathways↗
PubMed1991

Auditory nerve compound action potentials and brain stem auditory evoked potentials in patients with various degrees of hearing loss.

Click-evoked compound action potentials recorded in normal-hearing patients through a monopolar electrode placed on the intracranial portion of the eighth nerve were compared with the responses recorded in patients with high-frequency hearing loss or with high- and low-frequency hearing losses. That multiple peaks appear in the compound action potential in patients with hearing loss implies that click sounds elicit successive and separated volleys of neural excitation in the ascending auditory pathway, whereas click sounds in patients with normal hearing mainly give rise to a single volley of neural activity. This difference in the pattern of auditory nerve activity might explain why there are often multiple peaks in the brain stem auditory evoked potentials in patients with hearing loss and that the peaks are often less well-defined than peaks in patients with normal hearing.

Audiometry, Evoked Response↗
PubMed1991

Vascular compression of the eighth cranial nerve as a cause of vertigo.

Some patients have vertigo that is more or less constant, associated with varying degrees of nausea, and only relieved by bedrest. This disorder, named disabling positional vertigo (DPV), was found to be caused by a blood vessel or vessels compressing the eighth cranial nerve in its intracranial portion, and it can be relieved by microvascular decompression (MVD) of the nerve. Important in the differential diagnosis of DPV are a detailed history, the results of audiometry (10 to 15 dB interaural threshold difference or a small mid-frequency notch), acoustic middle ear reflex response testing (may be abnormal), and recordings of brainstem auditory evoked potentials (BAEP). BAEP in such cases show increased conduction time in the auditory nerve and/or prolonged latency of wave V recorded from the contralateral ear, possibly the result of brainstem compression. Abnormalities on vestibular testing often do not reflect the severity of the illness. Forty-one patients who underwent MVD to treat DPV in one year at the author's institution have been followed for 4.5 to 5.5 years. By self-evaluation, 20 had excellent and 10 good results of the operation. The success of this procedure is even higher today, since it was found that very small blood vessels, including veins, can cause DPV; thus all vessels touching the nerve are now managed. Complications of MVD are rare. The most frequent, hearing loss, occurred in only one patient in this series.

Brain↗
PubMed1991

Longitudinal study of changes in speech perception between 70 and 81 years of age.

As part of a large gerontological study in Göteborg, Sweden, 376 randomly selected men and women born in 1901-1902 underwent pure-tone and speech audiometry at the age of 70 years in 1971-1972. The survivors of the 1901-1902 cohort were tested again at the ages of 75, 79 and 81 years. A second group consisting of 297 men and women born in 1906 was also tested with pure-tone and speech audiometry at the ages of 70 and 75 years. We found that the median speech discrimination scores for the 1901-1902 cohort decreased moderately with increasing age: between the ages of 70 and 81 years scores decrease 10% for men and 8% for women for the worse ear and 7 and 6% for the better ear in this group. The median speech reception threshold increased 15 dB over the 11-year period for both men and women, an increase in good agreement with the increase in the pure-tone threshold over this period. Those born in 1906 had a slightly lower discrimination score (4%) when tested at the age of 70 years compared to those born in 1901 tested at the same age. As many as half of the 81-year-old persons would have a theoretical benefit from hearing aid amplification.

Aged↗
PubMed1990

Results of microvascular decompression of the eighth nerve as treatment for disabling positional vertigo.

A total of 41 patients who underwent microvascular decompression to relieve disabling positional vertigo in one 12-month period were studied. At follow-up examinations 2 1/2 to 3 1/2 years after the operation, 30 patients had total relief of their symptoms or were considerably improved, to the point that they could resume normal work or other activities in which they were not able to engage before the operation. Two of the 41 patients had mild improvement, and the final 9 patients had no change in their symptoms. One patient, who had had a previous vestibular nerve section without improvement, underwent microvascular decompression of the stump as well as decompression of the opposite side with no relief: 3 of these 9 patients had clear signs of bilateral vestibular nerve compression, but elected not to undergo a second procedure at that time. One patient lost hearing as a result of the operation, and 1 who had a second operation suffered a hearing loss and subsequently underwent vestibular nerve section with improvement of the symptoms. Two patients had transient deficits related to cranial nerves IV and X. The remaining patients had no complications from the operation.

Acoustic Impedance Tests↗
PubMed1990

Vascular compression syndrome of the eighth nerve. Clinical correlations and surgical findings.

A recently described syndrome, disabling positional vertigo (DPV), is characterized by persistent and progressive vertigo that is always associated with nausea and occasionally with vomiting; symptoms are made worse with changes in head position and are lessened with bedrest. Patients with DPV have abnormal results on vestibular testing and abnormalities in auditory nerve conduction as indicated by subtle but distinct alterations in brain stem auditory evoked potentials (BAEP). Microvascular decompression (MVD) of the vestibular nerve and, when indicated, the cochlear portion of the eighth cranial nerve has been highly successful in returning patients with DPV to normal lifestyles. Intraoperative monitoring of BAEP and auditory nerve compound action potentials have reduced the incidence of hearing loss, the major complication of MVD of the eighth nerve, to about 3 per cent. This article details the results of evaluating and treating 41 patients with DPV by MVD over a 12-month period and reports a success rate for this procedure in these patients of 73 per cent.

Humans↗
PubMed1989

Does intraoperative monitoring of auditory evoked potentials reduce incidence of hearing loss as a complication of microvascular decompression of cranial nerves?

During a 14-month period, 129 individuals underwent 140 operations for microvascular decompression to relieve hemifacial spasm, disabling positional vertigo, tinnitus, or trigeminal neuralgia at our institution. Seven patients were operated upon twice on the same side and 4 were operated upon on both sides at different times. In each case, the brainstem auditory evoked potentials were monitored intraoperatively by the same neurophysiologist. In 75 of these operations, compound action potentials were also recorded from the exposed 8th nerve. Comparison of speech discrimination scores before the operation and at the time of discharge showed that at discharge, discrimination had decreased in 7 patients by 15% or more and increased in 4 patients by 15% or more, in 2 patients by as much as 52%. Essentially similar results were obtained when preoperative speech discrimination scores were compared with results obtained from the 87 patients who returned for a follow-up visit between 3 and 6 months after discharge. Only one patient lost hearing (during a second operation to relieve hemifacial spasm). Another patient (also operated upon to relieve hemifacial spasm) suffered noticeable hearing loss postoperatively, but had recovered nearly normal hearing by 4 months after the operation. Nine patients had an average elevation of the hearing threshold for pure tones in the speech frequency range (500 to 2000 Hz) of 11 dB or more at 4 to 5 days after the operation; 8 of these had fluid in their middle ears that most likely contributed to the hearing loss. Threshold elevations occurred at 4000 Hz and 8000 Hz in 19 and 29 ears, respectively.

Audiometry, Evoked Response↗
PubMed1989

Changes in pure-tone thresholds in individuals aged 70-81: results from a longitudinal study.

The results of audiometric evaluation of 376 randomly selected men and women, 70 years old and born in 1901, are reported. The investigation is part of a large study on a gerontological population in which the original participants were tested again with pure-tone and speech audiometry at ages 75, 79 and 81. We also report audiometric results obtained at ages 70 and 75 from a second group, consisting of 297 men and women born in 1906. Hearing loss was most pronounced at higher frequencies for both sexes, and men had an average of 10 dB greater hearing loss at 8 kHz than women. The decrease in hearing threshold in men between the ages of 70 and 81 was more pronounced at 2 kHz (27 dB) than at 4 and 8 kHz (15 and 20 dB, respectively). The average hearing loss in women increased at a constant rate between the ages of 70 and 79 (15 dB), while between the ages of 79 and 81 the changes in pure-tone threshold was minimal. There were no significant differences in pure-tone thresholds for women born in 1901 when compared to those born in 1906 at the ages of 70 and 75. However, men born in 1906 had a more pronounced hearing loss at the age of 75 than those born in 1901.

Age Factors↗
PubMed1988

Controversy in menière's disease: results of microvascular decompression of the eighth nerve.

We have identified a group of patients with classic symptoms of Meniere's disease, all of whom had abnormalities of brain stem auditory evoked potentials and middle ear acoustic reflex response that strongly indicated auditory nerve and brain stem involvement. Ten patients with disabling symptoms and retrocochlear audiologic signs were selected to undergo microvascular decompression of the eighth nerve at its exit from the brain stem (root exit zone [REZ]). In all 10 patients, the eighth nerve was found to be significantly compressed by one or several vessels near its REZ. One patient died 4 months after the operation from an unrelated cause but had been free of symptoms of Meniere's disease until her death; the remaining nine patients have all been free from vertigo for 8 to 48 months after the operation. None of the patients suffered any complications as a result of the surgical procedure.

Adult↗
PubMed1987

Self-assessment of hearing problems in an elderly population. A longitudinal study.

As part of a large population study, 386 randomly selected probands 70 years of age, representative of the population of an industrialized Swedish city, were questioned regarding hearing difficulties in different social conditions. The same questions were presented to the participants of that study, at the age of 75 and 79 years. The results showed that of the 70-year-old persons, more than 95% had quite a good estimate of their hearing capacity. The subjective hearing problems increased with increasing age. However, at the age of 79 years, 86% still had no hearing problems or had only slight or moderate difficulties. The males reported that they had more hearing problems than the females. The prevalence of irritating tinnitus was about the same for males as for the females (8%). The number of probands with severe tinnitus was constant throughout the investigated period. It is suggested that hearing difficulties experienced when talking to only one person can be used to estimate the need for hearing amplification. A comparison between two cohorts with an age difference of 5 years was made. In a difficult listening situation at the age of 70 years, the hearing of subjects born in 1906-07 was reportedly worse than that of these born in 1901-02.

Aged↗
PubMed1986

Diagnosis and surgical treatment of disabling positional vertigo.

This report reviews the characteristic symptoms of disabling positional vertigo (DPV), and the tests used to reach a differential diagnosis of this disorder. Twenty-one patients were operated on consecutively for management of DPV between March, 1983, and September, 1984. In all patients one or more arteries or veins was found to be compressing the eighth cranial nerve when the nerve was exposed for microvascular decompression to relieve the symptoms of DPV. After the operation, 16 of the 21 patients were free of symptoms, or symptoms were so much improved that the patients returned to normal work or social life. Two patients had no improvement and three had limited relief of symptoms postoperatively. None of the patients experienced hearing loss as a result of the operation to relieve DPV, but one patient suffered a cerebellar contusion during the operation.

Adolescent↗
PubMed1985

Otoneurological examination in panic disorder and agoraphobia with panic attacks: a pilot study.

A battery of vestibular and audiological tests was administered to eight patients with panic disorder and 13 patients with agoraphobia and panic attacks, all of whom experienced dizziness during their panic attacks. Positional or spontaneous nystagmus was present in 67% of the subjects. Abnormal responses were found in caloric testing (56%), rotational testing (35%), and posturography (32%). Pure tone audiograms were abnormal in 26% of the subjects and acoustic reflexes were abnormal in 44% of the subjects. Six of eight patients tested had an abnormal brainstem auditory evoked potential. The possible importance of the findings and their implications for further research are discussed.

Adult↗
PubMed1985

Audiometric abnormalities in hemifacial spasm.

One-hundred forty-three patients with hemifacial spasm (HFS) as a primary disorder were evaluated pre- and postoperatively by pure-tone and speech audiometry, determination of thresholds for the acoustic middle ear reflex, and recording of auditory brainstem responses. We found an unusual 'notch' in the pure-tone audiograms of 16 patients (11%) and a low-frequency up-sloping pure-tone threshold in another 17 patients (12%). Because such abnormalities occur rarely, it may be assumed that they are related to these patients' primary disorder. All of the patients underwent microvascular decompression to relieve their spasms, and it was confirmed during surgery that in all patients the seventh cranial nerve was compressed at its root entry zone by vascular structures. It is therefore assumed that the abnormality of pure-tone threshold function noted in 23% of the patients with HFS was caused by compression of the auditory nerve by the same vessel as that which compressed the facial nerve. Since the changes in the pure-tone threshold occurred in the mid- and low-frequency range, it is assumed that low-frequency fibers constitute the outer part of the auditory nerve at its entrance into the human brainstem.

Audiometry, Pure-Tone↗
PubMed1985

Loss of auditory function in microvascular decompression for hemifacial spasm. Results in 143 consecutive cases.

Auditory function was studied before and after surgery in 143 consecutive patients who were operated on for hemifacial spasm by microvascular decompression of the intracranial portion of the facial nerve. The acoustic middle ear reflex was abnormal preoperatively in 41% of the patients, indicating that the vascular abnormalities that caused the hemifacial spasm also affected the auditory nerve. Three patients suffered a profound hearing loss in the ear on the operated side, and one lost hearing function totally. In addition, 24 patients had a moderate elevation in the pure-tone threshold at one or more octave frequencies. Of these, 16 patients experienced a hearing loss at only one frequency (8000 Hz), while eight had a threshold evaluation of no more than 20 dB in the speech frequency range (500, 1000, and 2000 Hz). Two patients were deaf on the side of the spasm before the operation. Three patients were not tested postoperatively, and one patient was tested only after surgery. Thus, in this series of 143 patients, only 2.8% suffered a significant hearing loss as a complication of facial nerve decompression to relieve hemifacial spasm.

Adult↗
PubMed1984

Disabling positional vertigo.

We have identified a group of patients with vestibular disorders whose symptoms are not consistent with the commonly recognized syndromes such as Meniere's disease, benign paroxysmal positional vertigo, and vestibular neuronitis. These patients have a constant positional vertigo and are often nauseated to an extent that makes them disabled. Their symptoms do not respond to conventional medical treatment or habituating therapy. We have found specific clinical-pathological signs in these patients that indicate that the vestibular nerve is compressed intracranially by blood vessels. Treatment of nine such patients by microvascular decompression of the eighth nerve brought total relief of symptoms in eight patients and improvement in one. We suggest that this syndrome be named disabling positional vertigo.

Adult↗
PubMed1984

Technique of hearing preservation in small acoustic neuromas.

The ideal operation for acoustic neurinoma would not only provide total excision without injury to the brain stem and with preservation of facial nerve function, but would also allow retention of useful hearing in those patients who come to operation with intact hearing function. Documented preservation of useful hearing in the rather extensive literature concerning acoustic neurinomas is rare. An operative technique has been developed utilizing a retromastoid approach, brain stem auditory-evoked potentials and direct auditory monitoring, facial nerve electromyography, and microsurgical techniques that have enabled us to preserve useful hearing in three and some hearing in two of six consecutive patients who had preoperative hearing. Rules regarding preservation and criteria regarding documentation of hearing preservation are outlined.

Adult↗