Abstract
A long-lasting dizzy sensation is a common complaint in elderly subjects. The pathogenesis and effective treatment of such chronic dizziness (CD), however, have not yet been fully elucidated because of lack of methods for evaluating this sensation. On the basis of assumption that CD may be attributable partly to cortical functional abnormality, we attempted to estimate the function of auditory cortex by measurements of auditory-evoked magnetic fields (AEFs). Magnetic field signals in the parieto-temporal cortex were evoked by 1000-Hz tone-burst with 90-dB normal hearing level sounds, and the highest-amplitude magnetic waveforms at approximately 100-ms (N100m) were analyzed as electrical current arrows in normal subjects (n=11), patients with CD (n=27) and patients with cerebral infarction but no dizzy sensation (n=9). In the normal subjects, the current arrows pointed to a nearly straight line with small directional distortion as indicated by a rotation-degree parameter, dIrot of 1.59±0.46. In 17 of 27 CD patients, the directions of current arrows were markedly distorted showing abnormally high dIrot values greater than 2.50 (the mean plus two standard deviations of normal values) and disclosed a clockwise or counter-clockwise rotation in either side or both sides of parieto-temporal cortex. In all the patients with cerebral infarction, the current arrows exhibited the similar pattern as the normal subjects. None of them exhibited abnormally high dIrot values. We hypothesized that the rotational abnormality may be caused by abnormal neuronal excitation, since non-evoked magnetic fields in temporal lobe epilepsy demonstrated the similar current rotational abnormality as reported previously. Seven CD patients were treated with anticonvulsants, and four showed remarkable amelioration of dizzy sensation. In all the four patients with symptomatic amelioration, the disappearance of rotational abnormality in AEFs or the tendency towards disappearance was observed following symptomatic amelioration. The results of the present study suggest that the auditory center may contribute to the maintenance of equilibrium, and its dysfunction may lead to the development of CD. AEFs measurements may make it possible to evaluate the functional abnormality of auditory center and may be useful for studying the pathophysiology and treatment of CD.
| Original language | English |
|---|---|
| Pages (from-to) | 373-381 |
| Number of pages | 9 |
| Journal | Brain Research |
| Volume | 957 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Dec 13 2002 |
| Externally published | Yes |
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Keywords
- Auditory cortex
- Auditory-evoked magnetic field
- Chronic dizziness
- Epilepsy
- Neuronal electrical current
- Vestibular cortex
ASJC Scopus subject areas
- Neuroscience(all)
Cite this
Cortical functional abnormality assessed by auditory-evoked magnetic fields and therapeutic approach in patients with chronic dizziness. / Oe, Hiroshi; Kandori, Akihiko; Murakami, Masahiro; Miyashita, Kotaro; Tsukada, Keiji; Naritomi, Hiroaki.
In: Brain Research, Vol. 957, No. 2, 13.12.2002, p. 373-381.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Cortical functional abnormality assessed by auditory-evoked magnetic fields and therapeutic approach in patients with chronic dizziness
AU - Oe, Hiroshi
AU - Kandori, Akihiko
AU - Murakami, Masahiro
AU - Miyashita, Kotaro
AU - Tsukada, Keiji
AU - Naritomi, Hiroaki
PY - 2002/12/13
Y1 - 2002/12/13
N2 - A long-lasting dizzy sensation is a common complaint in elderly subjects. The pathogenesis and effective treatment of such chronic dizziness (CD), however, have not yet been fully elucidated because of lack of methods for evaluating this sensation. On the basis of assumption that CD may be attributable partly to cortical functional abnormality, we attempted to estimate the function of auditory cortex by measurements of auditory-evoked magnetic fields (AEFs). Magnetic field signals in the parieto-temporal cortex were evoked by 1000-Hz tone-burst with 90-dB normal hearing level sounds, and the highest-amplitude magnetic waveforms at approximately 100-ms (N100m) were analyzed as electrical current arrows in normal subjects (n=11), patients with CD (n=27) and patients with cerebral infarction but no dizzy sensation (n=9). In the normal subjects, the current arrows pointed to a nearly straight line with small directional distortion as indicated by a rotation-degree parameter, dIrot of 1.59±0.46. In 17 of 27 CD patients, the directions of current arrows were markedly distorted showing abnormally high dIrot values greater than 2.50 (the mean plus two standard deviations of normal values) and disclosed a clockwise or counter-clockwise rotation in either side or both sides of parieto-temporal cortex. In all the patients with cerebral infarction, the current arrows exhibited the similar pattern as the normal subjects. None of them exhibited abnormally high dIrot values. We hypothesized that the rotational abnormality may be caused by abnormal neuronal excitation, since non-evoked magnetic fields in temporal lobe epilepsy demonstrated the similar current rotational abnormality as reported previously. Seven CD patients were treated with anticonvulsants, and four showed remarkable amelioration of dizzy sensation. In all the four patients with symptomatic amelioration, the disappearance of rotational abnormality in AEFs or the tendency towards disappearance was observed following symptomatic amelioration. The results of the present study suggest that the auditory center may contribute to the maintenance of equilibrium, and its dysfunction may lead to the development of CD. AEFs measurements may make it possible to evaluate the functional abnormality of auditory center and may be useful for studying the pathophysiology and treatment of CD.
AB - A long-lasting dizzy sensation is a common complaint in elderly subjects. The pathogenesis and effective treatment of such chronic dizziness (CD), however, have not yet been fully elucidated because of lack of methods for evaluating this sensation. On the basis of assumption that CD may be attributable partly to cortical functional abnormality, we attempted to estimate the function of auditory cortex by measurements of auditory-evoked magnetic fields (AEFs). Magnetic field signals in the parieto-temporal cortex were evoked by 1000-Hz tone-burst with 90-dB normal hearing level sounds, and the highest-amplitude magnetic waveforms at approximately 100-ms (N100m) were analyzed as electrical current arrows in normal subjects (n=11), patients with CD (n=27) and patients with cerebral infarction but no dizzy sensation (n=9). In the normal subjects, the current arrows pointed to a nearly straight line with small directional distortion as indicated by a rotation-degree parameter, dIrot of 1.59±0.46. In 17 of 27 CD patients, the directions of current arrows were markedly distorted showing abnormally high dIrot values greater than 2.50 (the mean plus two standard deviations of normal values) and disclosed a clockwise or counter-clockwise rotation in either side or both sides of parieto-temporal cortex. In all the patients with cerebral infarction, the current arrows exhibited the similar pattern as the normal subjects. None of them exhibited abnormally high dIrot values. We hypothesized that the rotational abnormality may be caused by abnormal neuronal excitation, since non-evoked magnetic fields in temporal lobe epilepsy demonstrated the similar current rotational abnormality as reported previously. Seven CD patients were treated with anticonvulsants, and four showed remarkable amelioration of dizzy sensation. In all the four patients with symptomatic amelioration, the disappearance of rotational abnormality in AEFs or the tendency towards disappearance was observed following symptomatic amelioration. The results of the present study suggest that the auditory center may contribute to the maintenance of equilibrium, and its dysfunction may lead to the development of CD. AEFs measurements may make it possible to evaluate the functional abnormality of auditory center and may be useful for studying the pathophysiology and treatment of CD.
KW - Auditory cortex
KW - Auditory-evoked magnetic field
KW - Chronic dizziness
KW - Epilepsy
KW - Neuronal electrical current
KW - Vestibular cortex
UR - http://www.scopus.com/inward/record.url?scp=0037073549&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037073549&partnerID=8YFLogxK
U2 - 10.1016/S0006-8993(02)03555-2
DO - 10.1016/S0006-8993(02)03555-2
M3 - Article
C2 - 12445982
AN - SCOPUS:0037073549
VL - 957
SP - 373
EP - 381
JO - Brain Research
JF - Brain Research
SN - 0006-8993
IS - 2
ER -