Brain-Stem Auditory Evoked Response

來源丨《Blackwell’s Five-Minute Veterinary Consult》

翻譯丨寵物神經(jīng)科醫(yī)生高健?

BASICS 基礎(chǔ)

TYPE OF PROCEDURE 檢查類型

Electrodiagnostic 電診斷

PROCEDURE EXPLANATION AND RELATED PHYSIOLOGY
檢查解釋和相關(guān)生理學(xué)

The brain-stem auditory evoked response (BAER) is a graphic record- ing of the evoked response in brain-stem activity elicited by an auditory stimulus. The test is performed by providing a repetitive auditory stimulus to 1 ear while providing a masking noise to the other ear.

腦干聽覺誘發(fā)反應(yīng)（BAER）是對(duì)聽覺刺激引起的腦干活動(dòng)的誘發(fā)反應(yīng)的圖形記錄。

該檢查通過向一只耳朵提供重復(fù)的聽覺刺激，
同時(shí)向另一只耳朵提供噪聲屏蔽來進(jìn)行。

The sounds are transmitted by earphones placed in the ear canal. The evoked potentials are recorded from subdermal scalp electrodes; because these potentials are relatively small, the waveforms are averaged to eliminate extraneous electrical activity. A normal BAER consists of 4–5 highly reproducible, time-locked waves obtained within 10 ms of the stimulus and represent activation of structures along the auditory pathway in the brain stem. The first large wave (wave I) is generated by action potentials in the cochlear division of the vestibulocochlear nerve (cranial nerve VIII). Subsequent waves are generated by brain-stem nuclei and tracts that comprise the auditory pathway, including the cochlear nucleus, rostral olivary nucleus, lateral lemniscus, and caudal colliculus.

聲音通過放置在耳道中的耳機(jī)傳播。

誘發(fā)電位由頭皮皮下的電極進(jìn)行記錄;
由于這些電位相對(duì)較小，
所以對(duì)波形進(jìn)行平均以消除外來的電活動(dòng)。

一個(gè)正常的BAER由4-5個(gè)高度可重復(fù)的、時(shí)間鎖定（time-locked）的波組成，
這些波在刺激后10ms內(nèi)獲得，
代表了腦干中聽覺通路結(jié)構(gòu)的激活。

第一個(gè)大波（I波）是由前庭耳蝸神經(jīng)（第 VIII 對(duì)腦神經(jīng)）的耳蝸分支的動(dòng)作電位產(chǎn)生的。

隨后的波是由構(gòu)成聽覺通路的腦干神經(jīng)核和神經(jīng)束產(chǎn)生的，
包括耳蝸核（cochlear nucleus）、前側(cè)橄欖核（rostral olivary nucleus）、外側(cè)丘系（lateral lemniscus）和后丘（caudal colliculus）。

The BAER is an objective, noninvasive method of assessing the functional integrity of the inner ear and cochlear nerve, as well as the auditory pathways within the brain stem. In addition, disease of the external or middle ear can be evaluated to a limited extent, particularly in cases in which the disease limits the transmission of normal sound waves to the receptors in the inner ear.

BAER是一種客觀、無創(chuàng)的方法，
用于評(píng)估內(nèi)耳和耳蝸神經(jīng)，
以及腦干內(nèi)聽覺通路的功能完整性。

此外，
外耳或中耳疾病可以在有限程度上進(jìn)行評(píng)估，
特別是在某些疾病限制了正常聲波向內(nèi)耳受體傳遞的情況。

INDICATIONS 適應(yīng)癥

 To screen animals for congenital deafness?

? To assess for acquired deafness

? To evaluate brain-stem function

? 篩查動(dòng)物先天性耳聾

? 評(píng)估獲得性耳聾

? 評(píng)估腦干功能

CONTRAINDICATIONS 禁忌癥

None 無

POTENTIAL COMPLICATIONS 潛在并發(fā)癥

None 無

CLIENT EDUCATION 寵主教育

 As a test for hearing, the BAER evaluates each ear for the expected response to auditory stimulation, and animals with unilateral deafness can be identified. Animals with unilateral hearing loss may appear clinically normal to their owner.

作為一項(xiàng)聽力檢查，
BAER評(píng)估每只耳朵對(duì)聽覺刺激的預(yù)期反應(yīng)，
可以識(shí)別出單側(cè)耳聾的動(dòng)物。

在其寵主看來，
單側(cè)聽力喪失的動(dòng)物在臨床上可能表現(xiàn)是正常的。

 Partial hearing loss is more difficult to assess and is often not recognized. Similarly, a BAER cannot discriminate an animal’s ability to hear only certain frequencies or tones, because these characteristics of the stimulus are not varied during testing.

部分性聽力喪失更難評(píng)估，而且常常無法被識(shí)別。

同樣，
BAER也不能分辨出動(dòng)物只聽到某些頻率或音調(diào)的能力，
因?yàn)檫@些刺激的特征在檢查過程中是不會(huì)變化的。

BODY SYSTEMS ASSESSED 評(píng)估的身體系統(tǒng)

Nervous 神經(jīng)系統(tǒng)

PROCEDURE 檢查

PATIENT PREPARATION 病患預(yù)備

Preprocedure Medication or Preparation 檢查所需藥物或預(yù)備

None 無

Anesthesia or Sedation 麻醉或鎮(zhèn)靜

Animals that object to either the electrodes being placed subdermally on the scalp or the earphones inserted into the ear canals can be sedated for the procedure. Neither sedation nor anesthesia will affect the test results.

對(duì)于那些難以將電極置于頭皮皮下或?qū)⒍鷻C(jī)插入耳道的動(dòng)物，
可以在檢查過程中給它們鎮(zhèn)靜。

鎮(zhèn)靜和麻醉都不會(huì)影響檢測(cè)結(jié)果。

Patient Positioning 病患擺位

 The animal is placed in sternal recumbency.
 If the animal is not heavily sedated or anesthetized for the procedure, its head should be gently restrained to prevent the animal’s movement from dislodging the earphones or electrodes. Excessive movement will also cause electrical interference, and the elicited responses will not be averaged into the final waveform. This prolongs the time required to perform the test.

動(dòng)物俯臥位。

如果動(dòng)物在檢查過程中沒有深度鎮(zhèn)靜或麻醉，
那么它的頭部應(yīng)該被輕輕地保定好，
以避免動(dòng)物的運(yùn)動(dòng)導(dǎo)致耳機(jī)或電極脫落。

過度的運(yùn)動(dòng)也會(huì)引起電干擾，
引起的反應(yīng)不會(huì)被平均到最終的波形當(dāng)中。

這還會(huì)延長(zhǎng)執(zhí)行檢查所需的時(shí)間。

Patient Monitoring 病患監(jiān)測(cè)

None 無

Equipment or Supplies 設(shè)備或耗材

 An electrodiagnostic unit capable of performing BAER, which also has the auditory stimulator and transducer needed to create the audible clicks

 Scalp electrodes

? ?Specially designed, disposable tubal insert earphones

? 一個(gè)能夠執(zhí)行BAER的電診斷設(shè)備，同時(shí)還有聽覺刺激器和產(chǎn)生可聽到咔噠聲的換能器

? 頭皮上的電極

? 特別設(shè)計(jì)的一次性管式耳機(jī)

TECHNIQUE 技術(shù)

 The earphones are placed securely in the external ear canals.
 Subdural electrodes are placed at specific sites on the scalp; the recording electrode is placed at the vertex, the reference electrode at the mastoid just rostral to the base of the ear, and the ground electrode on the dorsal midline of the midcervical region.

 A 70- to 90-decibel click stimulus is applied to the test ear at a rate of 10 Hz while a masking noise of 30–40 decibels less than the test stimulus is applied to the opposite ear. Typically, 500–1,000 repetitions are averaged to produce the final waveform.

耳機(jī)確實(shí)地放置在外耳道中。

硬膜下電極被放置在頭皮的特定部位;
記錄電極（recording electrode）放置在頭頂點(diǎn)（vertex），
參考電極（reference electrode）放置在正好耳基部前側(cè)的乳突部，
接地電極（ground electrode）放置在頸中央?yún)^(qū)的背側(cè)中線處。

以10 Hz 的頻率將70- 90 分貝（decibel）的咔噠聲刺激施加到測(cè)試耳內(nèi)，
同時(shí)將比檢查刺激低 30-40分貝（DB）的掩蔽噪聲施加到另一只耳內(nèi)。

通常，需要平均500-1,000次重復(fù)波形來產(chǎn)生最終的波形。

SAMPLE HANDLING 采樣處置

N/A 無

APPROPRIATE AFTERCARE 恰當(dāng)?shù)臋z查后護(hù)理

Postprocedure Patient Monitoring 檢查后病患監(jiān)測(cè)

None 無

Nursing Care 醫(yī)療護(hù)理

None 無

Dietary Modification 飲食調(diào)整

None 無

Medication Requirements 藥物需求

None 無

Restrictions on Activity 活動(dòng)限制

None?無

Anticipated Recovery Time 所需恢復(fù)時(shí)間

None?無

INTERPRETATION 判讀

NORMAL FINDINGS OR RANGE 正常發(fā)現(xiàn)或范圍

A BAER is evaluated with respect to the number of waveforms present, as well as the latency and relative amplitude of the waveforms. The BAER normally results in 4–5 waveforms; expected latencies for each of the generated waveforms have been established for dogs and cats. As a general rule, wave I appears at a latency of approximately 1 ms, with each successive peak occurring at <1-ms intervals (Figure 1).

BAER是根據(jù)所出現(xiàn)的波形的數(shù)量，
以及波形的時(shí)長(zhǎng)和相對(duì)振幅來評(píng)估的。

BAER通常產(chǎn)生4-5個(gè)波形;

對(duì)于犬貓，
已經(jīng)建立了每種產(chǎn)生的波形的預(yù)期時(shí)長(zhǎng)。

一般來說，
I波出現(xiàn)的時(shí)長(zhǎng)約為1ms，
每個(gè)連續(xù)的峰值間隔為<1-ms（圖1）。

ABNORMAL VALUES 異常值

 When used as an assessment of hearing, the absence of any identifiable waveforms (a flat line) is indicative of deafness in the ear being tested.

當(dāng)用作聽力評(píng)估時(shí)，
缺失所有可識(shí)別的波形（一條平坦的線）時(shí)，表明被檢查那只耳朵耳聾。

 An increase in the latency of all waveforms and an increase in the stimulus intensity necessary to obtain a detectable response are suggestive of conductive hearing loss. This disturbance of transmission through the external or middle ear can be caused by otitis externa, tympanic membrane rupture, otitis media, or disease of the bony ossicles.

所有波形時(shí)長(zhǎng)的延長(zhǎng)，和獲得可檢測(cè)出的反應(yīng)所必需的刺激強(qiáng)度的增加，
均表明傳導(dǎo)性聽力損失（conductive hearing loss）。

外耳炎、鼓膜破裂、中耳炎或骨性聽小骨的疾病，
均可引起外耳或中耳的傳播障礙。

 Increased latency between waveform peaks is indicative of a brainstem lesion causing delayed conduction along the auditory pathway. Similarly, a ratio of wave V amplitude to wave I amplitude of <0.5 indicates brain-stem disease. However, brain-stem disease can be present without alterations in the BAER if the auditory pathways are not involved in the disease process.

波形峰值之間的時(shí)長(zhǎng)延長(zhǎng)，
提示腦干病變，
從而導(dǎo)致沿聽覺通路的傳導(dǎo)延遲。

同樣，
V波振幅與I波振幅之比為<0.5時(shí)，
提示存在腦干疾病。

然而，
如果聽覺通路沒有被疾病過程所波及，
那么腦干疾病可以不引起B(yǎng)AER改變。

 An animal with a severe, irreversible brain lesion compatible with brain death will have complete loss of all waves or a preservation of wave I with an absence of all subsequent waves.

伴有與腦死亡相關(guān)的嚴(yán)重、不可逆的腦損傷的動(dòng)物，
將會(huì)出現(xiàn)所有腦波的完全喪失，
或保留I波，而沒有所有后續(xù)腦波。

CRITICAL VALUES?臨界值

None 無

INTERFERING FACTORS 干擾因素

Drugs That May Alter Results of the Procedure

可能影響檢查結(jié)果的藥物

None 無

Conditions That May Interfere with Performing the Procedure

可能影響實(shí)施檢查結(jié)果的情況

None 無

Procedure Techniques or Handling That May Alter Results

可能影響檢查結(jié)果的檢查技術(shù)或處置

None 無

Influence of Signalment on Performing and Interpreting the Procedure

動(dòng)物特征對(duì)檢查執(zhí)行和解釋的影響

Species 物種
None 無

Breed 品種

None 無

Age 年齡

 Studies have demonstrated that the BAER thresholds mature in dogs and cats by approximately 3 weeks of age.

研究表明，犬貓的BAER閾值在大約3周齡時(shí)才成熟。

Hereditary deafness associated with the white or merle coat color is due to cochlear agenesis or early degeneration. Animals of predisposed breeds can be screened for congenital deafness as early as 5–6 weeks of age. If the results of initial screening are equivocal, it is recommended that the test be repeated in 1 month.

遺傳性耳聾與白色或隕石色（merle）的被毛有關(guān)，
可能是由于耳蝸發(fā)育不全（cochlear agenesis）或早期變性/退變（early degeneration）所致。

好發(fā)品種的動(dòng)物可在5-6周齡時(shí)進(jìn)行先天性耳聾篩查（congenital deafness）。

如果初步篩查的結(jié)果仍然不明確，建議1個(gè)月后再復(fù)查。

Gender 性別

None 無

Pregnancy 懷孕

None 無

CLINICAL PERSPECTIVE 臨床意義

 BAER testing is most commonly performed to screen for deafness in certain breeds of dogs that are predisposed to hereditary hearing loss, the most notable of which is the dalmatian. Hearing loss in these animals can be unilateral or bilateral.

BAER檢查最常用于篩查某些易患遺傳性聽力喪失的犬種的耳聾，
其中最著名的就是斑點(diǎn)犬（dalmatian）。

這些動(dòng)物的聽力喪失可能是單側(cè)的或雙側(cè)的。

 In a specialty-practice setting, BAER testing may be used as a tool to evaluate animals for brain-stem disease. This is most commonly performed in animals with vestibular disease, where differentiation of central from peripheral vestibular disease is important from diagnostic and prognostic standpoints.

在專科臨床實(shí)踐環(huán)境中，
BAER檢查可作為評(píng)估動(dòng)物腦干疾病的工具。

這在患有前庭疾病的動(dòng)物中最常見，
從診斷和預(yù)后的角度來看，
區(qū)分中樞性前庭疾病和外周性前庭疾病是很重要的。

 BAER testing can also be used to assess prognosis in animals with severe brain disease that has caused a comatose state. In these animals, an absence of waveforms is suggestive of irreversible brain injury. However, this assessment can be performed only in animals known to have normal hearing.

BAER檢測(cè)也可用于評(píng)估患有嚴(yán)重腦病并導(dǎo)致昏迷狀態(tài)的動(dòng)物的預(yù)后。

在這些動(dòng)物中，
某些波形的缺失提示著可能存在不可逆的腦損傷。

然而，
這種評(píng)估只能在已知聽力正常的動(dòng)物中進(jìn)行。

MISCELLANEOUS 其他

ANCILLARY TESTS 附加檢查

 A thorough otoscopic exam should be performed in any animal with an abnormal BAER (particularly when the animal fails to respond to a normal stimulus intensity or the latency of all waveforms is increased) to determine whether debris in the ear canal, severe canal stenosis, or rupture of the tympanic membrane is contributing to the hearing loss.

任何BAER異常的動(dòng)物（特別是當(dāng)動(dòng)物對(duì)正常刺激強(qiáng)度沒有反應(yīng)，或所有波形的時(shí)長(zhǎng)延長(zhǎng)時(shí)）都應(yīng)進(jìn)行全面的耳鏡檢查，
以確定是否有導(dǎo)致聽力喪失的耳道內(nèi)的碎屑、嚴(yán)重的耳道狹窄或鼓膜破裂等疾病。

 Animals with evidence, based on BAER testing, of brain-stem disease should undergo imaging of the brain and possible analysis of cerebrospinal fluid to assess for potential causes of the dysfunction.

根據(jù)BAER檢查，
有腦干疾病證據(jù)的動(dòng)物應(yīng)進(jìn)行腦部成像和可能需要腦脊液分析，
以評(píng)估功能障礙的潛在原因。

SYNONYMS 同義詞

 BAER
 Brain-stem auditory evoked potential 腦干聽覺誘發(fā)電位

SEE ALSO

Blackwell’s Five-Minute Veterinary Consult: Canine and Feline Topics

 Deafness
 Otitis Externa and Media Otitis Media and Interna

Related Topics in This Book

None

ABBREVIATIONS 縮寫

BAER = brain-stem auditory evoked response = 腦干聽覺誘發(fā)反應(yīng)

Suggested Reading 推薦閱讀

- Eger CE, Lindsay P. Effects of otitis on hearing in dogs characterized by brainstem auditory evoked response testing. J Small Anim Pract1997; 38: 380–386.

- Fischer A, Obermaier G. Brainstem auditory-evoked potentials and neuropathologic correlates in 26 dogs with brain tumors. J Vet Intern Med 1994; 8: 363–369.

- Holliday TA, Nelson HJ, Williams DC, Willits N. Unilateral and bilateral brainstem auditory-evoked response abnormalities in 900 Dalmatian dogs. J Vet Intern Med 1992; 6: 166–174.

- Steiss JE, Cox NR, Hathcock JT. Brain stem auditory-evoked response abnormalities in 14 dogs with confirmed central nervous system lesions. J Vet Intern Med 1994; 8: 293–298.

INTERNET RESOURCES 網(wǎng)絡(luò)資源

Strain GM. Deafness in dogs & cats. Louisiana State University School of Veterinary Medicine, http://www.lsu.edu/deafness/deaf.htm.

AUTHOR NAME 作者名字

Karen R. Mun ?ana

END