Implications for brainstem recovery from studies in primates after sensory loss from arm

For decades,researchers have known that when neurons lose their activating inputs,they can atrophy and even die.For example,removing sensory nerve inputs from the arm to the spinal cord after amputation or cutting the spinal nerves can shrink the post-synaptic target zones(e.g.,Woods et al.,2000).From touch receptors for the hand and arm,primary nerve afferents enter the spinal cord,and axons travel in the dorsal columns to target the cuneate nucleus(Cu)of the brainstem on the same side of the body(Figure 1).When sensory loss is unilateral,the overwhelming result is for the associated primary target zone to shrink in total size(cross-sectional area),as compared to the size of the opposite side.

Auditory brainstem functioning in individuals with misophonia

Purpose:Misophonia is not investigated much from an audiological perspective.Our study aims to examine the processing of the auditory retro-cochlear pathways in individuals with misophonia.Methods:A cross-sectional study was conducted among university students who had misophonia.The revised Amsterdam Misophonia Scale was used to determine the severity of misophonia.Participants were divided into mild and moderate-severe misophonia and compared with the healthy control group.Auditory Brainstem Response testing was recorded from all the individuals with misophonia.The absolute latency,amplitude,inter-peak latency difference,and inter-rate latency difference were compared between the groups.Results:One-way ANOVA result showed no significant difference in all the parameters of auditory brainstem response between the groups.These results are suggestive of normal brainstem processing in individuals with misophonia.Conclusions:The study concludes that the auditory pathway up to brainstem areas is intact in individuals with misophonia.Further studies are essential on a larger population for generalizing the results.

Early brainstem hemorrhage progression:multi-sequence magnetic resonance imaging and histopathology

According to clinical statistics,the mortality of patients with early brainstem hemorrhage is high.In this study,we established rat models of brainstem hemorrhage by injecting type Ⅶ collagenase into the right basotegmental pontine and investigated the pathological changes of early brainstem hemorrhage using multi-sequence magnetic resonance imaging and histopathological methods.We found that brainstem hematoma gradually formed in the injured rats over the first 3 days and then reduced after 7 days.The edema that occurred was mainly of the vasogenic type.No complete myelin sheath structure was found around the focus of the brainstem hemorrhage.The integrity and continuity of nerve fibers gradually deteriorated over the first 7 days.Neuronal degeneration was mild in the first 3 days and then obviously aggravated on the 7^(th)day.Inflammatory cytokines,interleukin-1β,and tumor necrosis factorαappeared on the 1st day after intracerebral hemorrhage,reached peak levels on the 3^(rd)day,and decreased from the 7^(th)day.Our findings show the characteristics of the progression of early brainstem hemorrhage.

Exploratory therapy for brainstem gliomas

Brainstem gliomas comprise both slow-growing and highly aggressive tumors,the latter carrying a dismal prognosis of approximately 10 months in children.Given their common locations along the brainstem,they are often not amenable to surgical resection.There are currently a host of exploratory therapies under investigation ranging from immunotherapy,small molecular inhibitors,epigenetic-modifying agents,and radiation protocols to combat these difficult-to-treat tumors.Recent discoveries highlighting the role of H3 histone mutations in diffuse midline glioma oncogenesis have yielded a variety of new targetable antigens and aberrant signaling pathways.Although many of these studies have shown promise in terms of inhibiting tumor growth and disease progression,results to date have been modest in their ability to translate into meaningful clinical benefit.This review will serve as an updated report on the current state of literature concerning pre-clinical and clinical therapies being investigated for brainstem glioma.In addition,this review will serve as a guide for clinicians as we review the evolving nomenclature of brainstem gliomas,commonly presenting symptoms,diagnostic tools,and standard therapies.

The characterization of auditory brainstem response(ABR) waveforms: A study in tree shrews(Tupaia belangeri)

To characterize the patterns of ABR waves in tree shrews, we must understand the hearing sensitivity and auditory function of healthy adult tree shrews. Fifteen tree shrews(30 ears) were stimulated with clicks and tone-pips at 11 different frequencies from 1 to 60 kHz. The ABR waves were recorded and analyzed. The ABR consisted of five to seven positive waves in the first 10 ms after a click stimulus, and the average hearing threshold of component III was 27.86 ± 3.78 dB SPL. Wave III was the largest and most clear. The ABR threshold was related to the tone-pip sitmulus by a "U" shaped curve. The sensitive frequency was approximately 8 kHz in tree shrews. The latencies systematically decreased with increasing stimulus frequencies. The ABR amplitudes of wave III increased as the sound pressure level increased. All of these results provide an empirical basis for future studies of hearing diseases in tree shrews.

Analysis of the mechanisms of rabbit's brainstem hemorrhage complicated with irritable changes in the alvine mucous membrane

AIM: To explore the dynamic changes in the pressure of the lateral ventricle during acute brainstem hemorrhage and the changes of neural discharge of vagus nerve under the load of intracranial hypertension, so as to analyze their effects on the congestive degree of intestinal mucous membrane and the morphologic changes of intestinal mucous membrane.METHODS: An operation was made to open the skull to obtain an acute brainstem hemorrhage animal model.Microcirculatory microscope photography device and video recording system were used to determine the changes continuously in the caliber of jejunal mesenteric artery during brainstem hemorrhage and the changes with time in the congestion of jejunal mucosal villi. We used HE stain morphology to analyze the changes of duodenal mucosal villi. A recording electrode was used to calculate and measure the electric discharge activities of cervical vagus nerve.RESULTS: (1) We observed that the pressure of lateral cerebral ventricle increased transiently during acute brainstem hemorrhage; (2) The caliber of the jejunal mesenteric artery increased during brainstem hemorrhage.Analysis of red color coordinate values indicated transient increase in the congestion of jejunal mucous membrane during acute brainstem hemorrhage; (3) Through the analysis of the pathologic slice, we found enlarged blood vessels, stagnant blood, and transudatory red blood cells in the duodenal submucous layer; (4) Electric discharge of vagus nerve increased and sporadic hemorrhage spots occurred in duodenal mucous and submucous layer, when the lateral ventricle was under pressure.CONCLUSION: Brainstem hemorrhage could causeintracranial hypertension, which would increase the neural discharge of vagus nerve and cause the transient congestion of jejunal mucous membrane. It could cause hyperemia and diffused hemorrhage in the duodenal submucous layer 48 h after brainstem hemorrhage.

Brainstem tegmental lesions in neonates with hypoxicischemic encephalopathy: Magnetic resonance diagnosis and clinical outcome

Lesions of the brainstem have been reported in the clinical scenarios of hypoxic-ischemic encephalopathy(HIE), although the prevalence of these lesions is probably underestimated. Neuropathologic studies have demonstrated brainstem involvement in severely asphyxiated infants as an indicator of poor outcome. Among survivors to HIE, the most frequent clinical complaints that may be predicted by brainstem lesions include feeding problems, speech, language and communication problems and visual impairments. Clinical series, including vascular and metabolic etiologies, have found selective involvement of the brainstem with the demonstration of symmetric bilateral columnar lesions of the tegmentum. The role of brainstem lesions in HIE is currently a matter of debate, especially when tegmental lesions are present in the absence of supratentorial lesions. Differential diagnosis of tegmental lesions in neonates and infants include congenital metabolic syndromes and drug-related processes. Brainstem injury with the presence of supratentorial lesions is a predictor of poor outcome and high rates of mortality and morbidity. Further investigation will be conducted to identify specific sites of the brainstem that are vulnerable to hypoxic-ischemic and toxic-metabolic insults.

A Phase II Study of Antineoplastons A10 and AS2-1 in Patients with Brainstem Gliomas. The Report on Non-Diffuse Intrinsic Pontine Glioma (Protocol BT-11)

Inoperable brainstem gliomas (BSG) are among the most difficult to treat malignancies. In the intent-to-treat (ITT) population of the BT-11 study for BSG, forty patients (median age 11.2 years old) were enrolled. Antineoplastons A10 and AS2-1 (ANP) were administered intravenously daily. The median daily dose of A10 was 8.70 g/kg/day and AS2-1 was 0.32 g/kg/day. Efficacy analyses were conducted in two subgroups: recurrent pediatric diffuse intrinsic pontine glioma (RPDIPG, N?= 17) and non-diffuse intrinsic pontine glioma (NDIPG, N?= 11). This paper reports the results of the study of the efficacy and safety of ANP in patients with NDIPG. The results in the RPDIPG group were reported before;complete response (CR) was 6%, partial response (PR) 23.5%, and stable disease (SD) 17.6%. One year overall survival (OS) was 29.4%, 2 years 11.8%, and 5, 10, and 15 years 6%. In the NDIPG group, there were 36% CR and 27.5% SD. OS at 1, 5, 10, and 15 years was 82%, 73%, 62%, and 50% correspondingly. There was only one serious adverse event (9%) reported in NDIPG represented by hypokalemia, Grade 4. The results suggest that ANP shows efficacy and an acceptable tolerability profile in patients with RPDIPG and NDIPG.

A case of overlapping Bickerstaff’s brainstem encephalitis and Guillain-Barré syndrome

Objective： There is no report on Bickerstaff s brainstem encephalitis （BBE） patients in China. We here report the first case of BBE in China. Methods： Clinical features, results of electromyography, eleetroencephalography （EEG）, magnetic resonance imaging （MRI） and cerebrospinal fluid （CSF） examination were studied to clarify the characteristics of this syndrome. Results： A 44-year-old man presented himself at our inpatient department with somnolence and dizziness as his initial symptoms. He developed multiple cranial nerves paralysis especially internal and external ophthalmoplegia, ataxia and tetraparesis within 1 week. His condition rapidly deteriorated, and he experienced coma. Electromyography showed indications of peripheral nerve dysfunction, electroencephalography revealed loss of basic rhythm, MR1 demonstrated high-intensity abnormalities on T2-weighted images of medulla oblongata, and CSF albuminocytological dissociation was defined abnormally as high protein. Ten months later, he almost completely recovered. Conclusion： BBE, fisher syndrome （FS） and Guillain-Barre syndrome （GBS） are similar clinically; BBE and FS were proposed to be the variant of GBS.

Brainstem auditory evoked potentials in patients with delayed encephalopathy after acute carbon monoxide poisoning

Objective:To evaluate the changes of brainstem auditory evoked potential (BAEP) in patients with delayed encephalopathy after acute carbon monoxide poisoning. Methods: BAEPs were performed in 32 controls and 40 patients. Wave Ⅰ , Ⅱ , Ⅲ ,Ⅳ, Ⅴ latencies and Ⅰ-Ⅲ , Ⅲ-Ⅴ , Ⅰ-Ⅴ interpeak latencies were measured, respectively. Results: Abnormalities of BAEPs in 13 patients (13/40, 32 ％). Among the13 abnormal BAEPs, 3 displayed prolongation of latency to waves in one side, no potential in another side; 5 displayed a similar abnormality which was bilateral prolongation of latency to waves ;and another 5 displayed unilateral latency delay. Compared wave Ⅰ , Ⅱ , Ⅲ , Ⅳ, Ⅴ latencies and Ⅰ-Ⅲ , Ⅲ-Ⅴ , Ⅰ-Ⅴ interpeak latencies in the patients and the controls, there were no significant differences (P＞0.05). Conclusion: BAEPs can be used for evaluating the diagnostic and prognostic values in the cases of delayed encephalopathy after acute carbon monoxide poisoning.

Characteristics of brainstem auditory evoked potentials of students studying folk dance

BACKGROUND： Previous experiments have demonstrated that brainstem auditory evoked potential is affected by exercise, exercise duration, and frequency. OBJECTIVE： Comparing the brainstem auditory evoked potential of students studying folk dance to students studying other subjects. DESIGN： Observational contrast study. SETTING： Physical Education College, Shandong Normal University PARTICIPANTS： Fifty-five female students were enrolled at Shandong Normal University between September and December in 2005, including 21 students that studied folk dance and 34 students that studied other subjects. The age of the folk dance students averaged （19 ± 1） years and dance training length was （6.0 ± 1.5） years. The students that studied other subjects had never taken part in dance training or other physical training, and their age averaged （22 ± 1） years, body height averaged （162 ± 5） cm, body mass averaged （51 ± 6） kg. All subjects had no prior ear disease or history of other neurological disorders. All students provided informed consent for the experimental project. METHODS： The neural electricity tester, NDI-200 （Shanghai Poseidon Medical Electronic Instrument Factory） was used to examine and record Brainstem Auditory Evoked Potential values of the subjects during silence, as well as to transversally analyze the Brainstem Auditory Evoked Potential values. The electrode positions were cleaned and degreased with soapy water, followed by ethanol. The selected bipolar electrodes were situated on the head： recording electrodes were placed at the Baihui acupoint, and the reference electrode was placed at the mastoid of the measured ear, with grounding electrodes in the center of the forehead. Brainstem Auditory Evoked Potential values were elicited by monaural stimulation of a ＂click＂ though an earphone; the other ear was sheltered by the white noise. The click intensity was 102 db, the stimulation frequency was 30 Hz, the bandpass filters were 1 000-3 000 Hz, the sensitivity was 5 ta V, and a total of 2 000 sweeps were averaged. Waveform identification and analysis： various components of the Brainstem Auditory Evoked Potential values were identified, and the peak latencies and peak-peak values were analyzed. MAIN OUTCOME MEASURES： Latency of Ⅰ , Ⅱ, Ⅲ, Ⅳ, Ⅴ and Peak-Peak Value of Ⅰ, Ⅲ, Ⅴwere measured. RESULTS： Fifty-five subjects were enrolled in the final analysis, without any loss. Compared to the students who studied other subjects ① Ⅰ -Ⅴ peak latencies （PL）： Ⅳ PL of the right ear of the folk dance students was obviously longer （P 〈 0.05）; ② Ⅰ, Ⅲ, V peak-peak values：Ⅰ peak-peak values of the right ear were obviously higher （P 〈 0.05）. CONCUSION： ① PL of the right ear of the folk dance students was obviously longer, which indicates that dancing results in a stronger sensibility to auditory stimuli. ②. Peak-peak values were obviously higher, which indicates that long-term exercise enhances the music senses and synchrony of auditory nerve impulses.

Convulsive-like movements as the first symptom of basilar artery occlusive brainstem infarction:A case report

BACKGROUND Convulsive-like movements are rare in basilar artery occlusive cerebral infarction(BAOCI).These manifestations may easily be mistaken for epileptic seizures caused by compromised anterior circulation or by cortical lesions.Delayed diagnosis of this condition affects its subsequent treatment and prognosis.Therefore,it is critical to recognize this type of phenomenon in the early stage.CASE SUMMARY A 55-year-old male patient presented with unconsciousness,rigidity,and a paroxysmal twitch in both lower limbs.These conditions lasted for nearly 2 h and resembled status epilepticus.After the initial conditions subsided,hemiplegia occurred and then subsided rapidly.The family refused thrombolytic therapy because the symptoms were similar to Todd paralysis after epilepsy.However,magnetic resonance imaging showed left pontine infarction.No abnormality was observed in a video electroencephalogram during the interictal period.Digital subtraction angiography revealed that the basilar artery was occluded and that the posterior communicating arteries were patent.Fortunately,the patient received a good prognosis after antiplatelet therapy,lipid regulation,balloon dilatation of the basilar artery,and rehabilitation.CONCLUSION Convulsive-like movements may be an early sign of basilar artery occlusive brainstem infarction.It is important to identify this phenomenon in a timely manner.

Magnetic resonance imaging differential diagnosis of brainstem lesions in children

Differential diagnosis of brainstem lesions,either isolated or in association with cerebellar and supra-tentorial lesions,can be challenging. Knowledge of the structural organization is crucial for the differential diagnosis and establishment of prognosis of pathologies with involvement of the brainstem. Familiarity with the location of the lesions in the brainstem is essential,especially in the pediatric population. Magnetic resonance imaging(MRI) is the most sensitive and specific imaging technique for diagnosing disorders of the posterior fossa and,particularly,the brainstem. High magnetic static field MRI allows detailed visualization of the morphology,signal intensity and metabolic content of the brainstem nuclei,together with visualization of the normal development and myelination. In this pictorial essay we review the brainstem pathology in pediatric patients and consider the MR imaging patterns that may help the radiologist to differentiate among vascular,toxico-metabolic,infectiveinflammatory,degenerative and neoplastic processes. Helpful MR tips can guide the differential diagnosis: These include the location and morphology of lesions,the brainstem vascularization territories,gray and white matter distribution and tissue selective vulnerability.

Awake craniotomy for auditory brainstem implant in patients with neurofibromatosis type 2:Four case reports

BACKGROUND The auditory brainstem implant(ABI)is a significant treatment to restore hearing sensations for neurofibromatosis type 2(NF2)patients.However,there is no ideal method in assisting the placement of ABIs.In this case series,intraoperative cochlear nucleus mapping was performed in awake craniotomy to help guide the placement of the electrode array.CASE SUMMARY We applied the asleep-awake-asleep technique for awake craniotomy and hearing test via the retrosigmoid approach for acoustic neuroma resections and ABIs,using mechanical ventilation with a laryngeal mask during the asleep phases,utilizing a ropivacaine-based regional anesthesia,and sevoflurane combined with propofol/remifentanil as the sedative/analgesic agents in four NF2 patients.ABI electrode arrays were placed in the awake phase with successful intraoperative hearing tests in three patients.There was one uncooperative patient whose awake hearing test needed to be aborted.In all cases,tumor resection and ABI were performed safely.Satisfactory electrode effectiveness was achieved in awake ABI placement.CONCLUSION This case series suggests that awake craniotomy with an intraoperative hearing test for ABI placement is safe and well tolerated.Awake craniotomy is beneficial for improving the accuracy of ABI electrode placement and meanwhile reduces non-auditory side effects.

THE EFFECTS OF SALICYLATE ON AUDITORY EVOKED POTENTIAL AMPLITWDE FROM THE AUDITORY CORTEX AND AUDITORY BRAINSTEM

Tinnitus has often been studied using salicylate in animal models as they are capable of inducing tempo-rary hearing loss and tinnitus. Studies have recently observed enhancement of auditory evoked responses of the auditory cortex (AC) post salicylate treatment which is also shown to be related to tinnitus like behavior in rats. The aim of this study was to observe if enhancements of the AC post salicylate treatment are also present at structures in the brainstem. Four male Sprague Dawley rats with AC implanted electrodes were tested for both AC and auditory brainstem response (ABR) recordings pre and post 250 mg/kg intraperitone-al injections of salicylate. The responses were recorded as the peak to trough amplitudes of P1-N1 (AC), ABR wave V, and ABR waveⅡ. AC responses resulted in statistically significant enhancement of ampli-tude at 2 hours post salicylate with 90 dB stimuli tone bursts of 4, 8, 12, and 20 kHz. Wave V of ABR re-sponses at 90 dB resulted in a statistically significant reduction of amplitude 2 hours post salicylate and a mean decrease of amplitude of 31%for 16 kHz. WaveⅡamplitudes at 2 hours post treatment were signifi-cantly reduced for 4, 12, and 20 kHz stimuli at 90 dB SPL. Our results suggest that the enhancement chang-es of the AC related to salicylate induced tinnitus are generated superior to the level of the inferior colliculus and may originate in the AC.

Brainstem abscesses caused by Listeria monocytogenes:A case report

BACKGROUNDIntracranial Listeria infections are common in newborns and immunocompromisedindividuals, but brainstem abscesses are rare.CASE SUMMARYWe report a rare case of brainstem abscesses caused by Listeria monocytogenes in apreviously healthy adult patient. The patient’s magnetic resonance imagingexamination showed multiple brain abscesses, and his second cerebrospinal fluidculture test indicated the presence of Listeria monocytogenes. Despite earlyempirical therapy, the patient’s condition progressively deteriorated. Because thepatient's abscesses were located in the brainstem and multiple lobes, surgery wasnot possible. The patient died 40 d after admission.CONCLUSIONThis case highlights the importance of rational clinical use of drugs to avoidpotentially serious infectious complications.

Unusual neural connection between injured cingulum and brainstem in a patient with subarachnoid hemorrhage

The human brain is known to have six cholinergic nudei （Selden et al., 1998; Nieuwenhuys et al., 2008）. The cerebral cortex obtains cholinergic innervation mainly from the basalis nucleus of Meynert （Ch 4） in the bas- al forebrain through the medial and lateral cholinergic pathways （Selden et al., 1998; Mesulam et al., 1983）. The cingulum, the neural fiber bundle connecting the basal forebrain and the medial temporal lobe, contains the medial cholinergic pathway （Selden et al., 1998; Hong and Jang, 2010）.

Weak cation exchange 2 protein chip for detecting differentially expressed brainstem proteins in a rat model of closed traumatic brain injury

BACKGROUND： Studies have reported the combined use of two-dimensional gel electrophoresis and mass spectrometry to detect differentially expressed proteins in the rat brainstem following brain injury. However, the detected differential proteins often exhibit low sensitivity and high relative molecular weight. Although protein chip technology is thought to compensate for these inadequacies, no related studies or results have been reported. OBJECTIVE： To propose the application of weak cation exchange protein chips in combination with mass spectrometry for determining protein expression profiles and characteristics in the brainstem following closed brain injury. DESIGN, TIME AND SETTING： Randomized, controlled, animal experiments utilizing proteomics were performed from June 2007 to December 2008 in the Proteomics Laboratory, Medical College of Chinese People＇s Armed Police Force. MATERIALS： Weak cation exchange 2 protein chip, Ciphergen Proteinchip System （PBS-IIC）. METHODS： A total of 72 rats were randomly assigned to two groups： sham-surgery （n = 12） and injury （n = 60）. A closed traumatic brain injury model caused by falling object was replicated in the injury group, which was then subdivided into five subgroups according to different time points after injury： 4, 8, 12, 24, and 48 hours, with 12 rats in each subgroup. In the sham-surgery group, only the skin was removed and the stainless steel pad was fixed to the skull. MAIN OUTCOME MEASURES： The brain injury rats were sacrificed at 4, 8, 12, 24, and 48 hours after injury, respectively, and the control rats were sacrificed at 24 hours. Pathological changes in the brainstem were determined using hematoxylin-eosin staining, and differential protein expression in the brainstem was detected using a weak cation exchange 2 protein chip and protein chip reader. RESULTS： In the sham-surgery group, cells appeared normal. However, in the brain injury group, some brainstem neurons exhibited pyknosis, with reduced numbers of Nissl bodies in the cytoplasm swollen cell bodies and nuclei, irregular staining in the cytoplasm, and decreased numbers of neurons. Results from weak cation exchange 2 protein chip detection demonstrated that, compared with the sham-surgery group, the expression profiles of 2 proteins were altered in the brainstem of the injury group. At 12, 24, and 48 hours after injury, expression was increased （P 〈 0.01 ）. The mass charge ratio （M/Z） of 7 862 differentially expressed proteins was greater in the sham-surgery group compared with 12 and 24 hours after injury （P 〈 0.05）. CONCLUSION： The combined method of weak cation exchange 2 protein chip and mass spectrometry detected differential protein expression in the brainstem following closed brain injury in the rats, which suggested that closed brain injury induced altered protein expression profiles in the brainstem.

Effect of Noise on the Function of Auditory Brainstem Center

The amplitudes and latencies of auditory brainstem evoked response(ABR)were recorded at both high(50/s)and low(10/s)click rates as sound stimuli before andafter the guinea pigs were exposed to variant intensity noise.The maximum amplitude ofwave V increased significantly,but those of wave Ⅰ,Ⅲ,and Ⅳ decreased significantly afterexposure to 110 dB noise for 20 or 30 min.The wave Ⅴ latency recorded at 50/s clickrate was shorter in every group after exposure.The changes of wave V latency recordedat 10/s click rate were complex,it was shorter after exposure to 95 dB or 105 dB for 10min;no change was found after exposure to 110 dB for 10 min,but it was longer initiallyand then became shorter after exposure to 110 dB noise for 30 min.The difference valueof wave V latency from 10/s to 50/s was negatively correlated with the noise intensityand exposure time.The more intense noise stimuli and the longer time,the less the differ-ence value became.The results indicate that the auditory bralnstem center was affectedby intense noise,and it is helpful to use difference value of wave V latency to analysis thefunction of brainstem center after exposure to noise.

The Auditory Brainstem and Middle Latency Responses in Healthy Mice

The auditory brainstern responses(ABR)and middle latency responses(MLR)were recorded in 24 normal mice with a 7S11A processor,and the normalparameters of ABR and MLR obtained.The results showed that the ABR of mice werecomposed of 6 waves,waves Ⅰ to Ⅵ.The mean threshold was 35.12±8.03 dB ,whichwas significantly different from the 22.63 dB of ABR found in guinea pigs.Thelatency of ABR waves Ⅰ to Ⅵizn the mice was found to be 1.30±8.03 ms ;2.02±0.24ms ;2.90±0.27 ms ;3.80±0.24 ms ;4.87±0.42 ms and 5.83±0.40 ms respectively.Nosex or strain differences were found.The MLR waveform of the mice were similar tothose of human and the latency was found to be P0 3.94±1.76 ms;P8.38±1.57ms;Na 14.98±2.54 ms;Pa 24.56±3.15 ms rcspectively.It is suggested that mice can beused for hearing research.Since the Na and Pa waves of MLR were unstable under anes-thesia,testing conditions for determining MLR in mice need further study.