Ipsilateral and contralateral auditory brainstem response reorganization in hemispherectomized patients.
BACKGROUND
Cortical hemispherectomy leads to degeneration of ipsilateral subcortical structures, which can be observed long term after the operation. Therefore, reorganization of the brainstem auditory pathway might occur. The aim of this study was to assess reorganization of brainstem auditory pathways by measuring the auditory brainstem response (ABR) in long-term hemispherectomized patients.


METHODS
We performed bilateral monaural stimulation and measured bilateral ABR in 8 patients ~20 years after hemispherectomy and 10 control subjects. Magnetic resonance imaging (MRI) was performed in patients to assess structural degeneration.


RESULTS
All patients showed degenerated ipsilateral brainstem structures by MRI but no significant differences in bilateral recording ABR wave latencies. However, nonsurgical-side stimulation elicited significantly longer wave V latencies compared to surgical-side stimulation. Differences in bilateral ABR were observed between hemispherectomized patients and control subjects. Waves III and V latencies elicited by nonsurgical-side stimulation were significantly longer than those in control subjects; surgical-side stimulation showed no significant differences.


CONCLUSIONS
(1) Differences in ABR latency elicited by unilateral stimulation are predominantly due to bilateral brainstem auditory pathway activity rather than to changes in brainstem volume; (2) ABR Waves III and V originate predominantly in the contralateral brainstem; and (3) subcortical auditory pathways appear to reorganize after long term hemispherectomy.
Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.
Ning
N
Yao
Department of Neuroelectrophysiology, Beijing Neurosurgical Institute, Beijing 100050, China.
Hui
H
Qiao
Department of Neuroelectrophysiology, Beijing Neurosurgical Institute, Beijing 100050, China.
Ping
P
Li
Department of Neuroelectrophysiology, Beijing Neurosurgical Institute, Beijing 100050, China.
Yang
Y
Liu
Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.
Liang
L
Wu
Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.
Xiaofeng
X
Deng
Department of Neurosurgery, Xuzhou Medical College Affiliated Hospital, Xuzhou Medical College, Jiangsu 221000, China.
Zide
Z
Wang
Medical Experiments and Testing Center, Capital Medical University, Beijing 100069, China.
Daxing
D
Chen
Department of Neurosurgery, Beijing Jishuitan Hospital, Beijing 100035, China.
Xianzeng
X
Tong
Department of Neurosurgery, The First Teaching Hospital of Xinjiang Medical University, Xinjiang Medical University, Xinjiang 830000, China.
Yuan
Y
Liu
Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.
Chenlong
C
Yang
Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.
Yulun
Y
Xu
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D038421:Hemispherectomy; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D012640:Seizures / Q000601:surgery; D055815:Young Adult