Rebecca J. Clark-Bash, R. EEG\EP T., CNIMeKnowledgePlus.net Page 1

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$Navigating the Auditory Pathway: Technical & Physiological Impact on IOM Rebecca Clark-Bash, R. EEG\EP T, CLTM, CNIM, F.$ $of the ASNM LOVES TO HAVE FUN WITH LEARNING 2 Rebecca Clark-Bash R. EEG\EP T., CNIM, CLTM, F.ASNM, F.ASET Knowledge Plus, Inc P.O. Box 356 Lincolnshire, Il 60069 Phone: 815.$

1 Navigating the Auditory Pathway: Technical & Physiological Impact on IOM Rebecca Clark-Bash, R. EEG\EP T, CLTM, CNIM, F.ASET, FASNM Faculty Rebecca Clark-Bash R. EEG\EP T., CLTM, CNIM, F.ASNM, F.ASET ASNM Board of Trustees ASET Board of Trustees CSET President First Technician on the ASNM Board Only Technician to be awarded Fellowship Status of the ASNM LOVES TO HAVE FUN WITH LEARNING 2 Rebecca Clark-Bash R. EEG\EP T., CNIM, CLTM, F.ASNM, F.ASET Knowledge Plus, Inc P.O. Box 356 Lincolnshire, Il Phone: opcal@aol.com CNIMeKnowledgePlus.net Page 1

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Sinister or LEFT EAR 2) AD: Auris Dexter

2 FREE POWER SESSIONS 4 AS 85 db HL 1) AS: Auris Sinister or LEFT EAR 2) AD: Auris Dexter or RIGHT EAR 5 1) Wave I is ONLY recorded in the Stimulated Ear 2) If Wave I is noted in the contralateral ear there is no contralateral ear WHITE NOISE MASKING at 60 db SPL 6 CNIMeKnowledgePlus.net Page 2

Contralateral Channel Function: 1) Validates White Noise Masking is being presented at appropriate intensity 2) Better Identification of Wave V (Better 4-5 Split in the contralateral ear) White Noise

3 Contralateral Channel Function: 1) Validates White Noise Masking is being presented at appropriate intensity 2) Better Identification of Wave V (Better 4-5 Split in the contralateral ear) White Noise Masking Prevents Bone Conducted Cross Over 7 1) Better Identification of Wave V (Better 4-5 Split in the contralateral ear) Identification of Wave V May also require: Decreasing Stimulation Intensity 8 Failure to use White Noise Masking may result in FALSE NEGATIVE: 1) Responses appear intact & unchanged 2) Patient has hearing loss post operatively 9 CNIMeKnowledgePlus.net Page 3

TYPES OF HEARING LOSS Also Called Involves Conductive Peripheral Ear Canal,Tympanic Membrane, Middle Ear Changes on BAEP Absolute Lat Normal Interpeaks Sensorineural Cochlear Cochlea -Normal or Near

4 TYPES OF HEARING LOSS Also Called Involves Conductive Peripheral Ear Canal,Tympanic Membrane, Middle Ear Changes on BAEP Absolute Lat Normal Interpeaks Sensorineural Cochlear Cochlea -Normal or Near Normal at High Click -At lower Click intensities increased Absolute Latency, Normal Interpeak Latencies Retrocochlear Central Brainstem Increased I-III or III-V and I-V 10 NORMAL: CONDUCTIVE AND SENSORINEURAL > Absolute Latencies Normal IPL RETROCOCHLEAR > Inter-peak Latencies I-III, III-V, I-V 11 1) Increase in Absolute Latency, Normal Interpeak Latencies 2) Normal or near normal at high intensity click stimulation, but at lower intensity stimulation, Increased absolute Latencies and normal Interpeak Amplitude or Amplitude Ratio: Never The Answer 12 CNIMeKnowledgePlus.net Page 4

Kinked Earphone Tubing 1) Increase in Absolute Latency, Normal Inter-peak Latencies 2) Normal or near normal at high intensity click stimulation, but

Irrigation Fluid In Tubing 1) Increase in Absolute Latency, Normal Inter-peak Latencies 2) Normal or near normal at high intensity click stimulation,

Earwax Also Called: 1) Increase in Absolute Latency, Normal Inter-peak Latencies 2) Normal or near normal at high intensity click stimulation, but at

5 Kinked Earphone Tubing 1) Increase in Absolute Latency, Normal Inter-peak Latencies 2) Normal or near normal at high intensity click stimulation, but at lower intensity stimulation, Increased absolute Latencies and normal Inter-peak 3) Increased I-III, Increased I-V Interpeak 13 Blood, Betadine or Irrigation Fluid In Tubing 1) Increase in Absolute Latency, Normal Inter-peak Latencies 2) Normal or near normal at high intensity click stimulation, but at lower intensity stimulation, Increased absolute Latencies and normal Inter-peak 3) Increased I-III, Increased I-V Interpeak 14 Excessive Earwax Also Called: 1) Increase in Absolute Latency, Normal Inter-peak Latencies 2) Normal or near normal at high intensity click stimulation, but at lower intensity stimulation, Increased absolute Latencies and normal Inter-peak 3) Increased I-III, Increased I-V Interpeak 15 CNIMeKnowledgePlus.net Page 5

6 Perforated or Hardened Tympanic Membrane 16 Middle Ear Infection Also Called: 17 Artificial Ventilation: Middle Ear 18 CNIMeKnowledgePlus.net Page 6

Otosclerosis Middle Ear intensity stimulation, Increased absolute Latencies and normal

20 Cholesteatoma Clinical Condition & Electrographic Coorelates Disease of the ear in

The cyst is not cancerous but can erode tissue and cause destruction of the ear.

7 Otosclerosis Middle Ear intensity stimulation, Increased absolute Latencies and normal Inter-peak 19 Cholesteatoma Middle Ear What modality(s) to monitor in surgery? 20 Cholesteatoma Clinical Condition & Electrographic Coorelates Disease of the ear in which a skin cyst grows into the middle ear and mastoid. The cyst is not cancerous but can erode tissue and cause destruction of the ear. The facial nerve runs through the middle ear cavity. For tumor removal facial nerve is monitored INFORMATIONAL 21 CNIMeKnowledgePlus.net Page 7

Mastoidectomy What modality(s) to monitor in surgery? 22 22 Tympanoplasty What modality(s) to monitor in surgery? 23 23 Tympanoplasty: Surgery that involves the tympanum (middle ear).

8 Mastoidectomy What modality(s) to monitor in surgery? Tympanoplasty What modality(s) to monitor in surgery? Tympanoplasty: Surgery that involves the tympanum (middle ear). The tympanum is the area of the ear behind the ear drum where the bones of hearing (ossicles) are located. Mastoidectomy: Surgery performed in the mastoid, where disease may occur Although hearing is at risk, monitoring Clinical Condition & th BAEP is not possible. Electrographic Coorelates Facial Nerve Monitoring is Indicated INFORMATIONAL 24 CNIMeKnowledgePlus.net Page 8

9 Porous Acousticus Surgery What modality(s2) to monitor in surgery? Meneires Disease Cochlea - Inner Ear EPISODIC: 1) Vertigo 2) Tinnitus 3) Hearing Loss BAEP: NORMAL 26 Meneires Disease: Surgery? Cochlea - Inner Ear Select One: 1) Microvascular Decompression 2) Endolymphatic Sac Decompression 3) Parotidectomy 4) Vestibular Schwannoma 27 CNIMeKnowledgePlus.net Page 9

the mastoid bone. The mastoid is opened, and the facial nerve is identified in its course through the mastoid.

10 Endolymphatic Sac Decompression Surgery Inner Ear What modality(s) 28 to monitor in surgery? 28 BAEP Surgical Correlates Endolymphatic Sac Decompression The endolymphatic sac decompression operation is performed by making an incision behind the involved ear and exposing the mastoid bone. The mastoid is opened, and the facial nerve is identified in its course through the mastoid. The bone over the endolymphatic sac is then exposed and once identified, the sac is opened. A non-reactive sheet of silastic or a valve is inserted into the sac to allow for future drainage, when fluid reforms. Theoperationtakesaboutanhour INFORMATIONAL High Frequency Hearing Loss Inner Ear - Cochlea 30 CNIMeKnowledgePlus.net Page 10

11 High Frequency Hearing Loss Inner Ear - Cochlea BROAD BAND CLICK clicks in the 2,000 to 4,000 Hz range of frequency These exact frequencies are affected with high frequency loss 31 Presbycusis Inner Ear - Cochlea 32 Acoustic Neuroma 33 CNIMeKnowledgePlus.net Page 11

Vestibular Schwannoma 34 Neurofibromatosis Type II 35 Guidelines 11 1994 Acoustic Neuroma Associated with neurofibromatosis A genetically-inherited disorder in which the nerve tissue grows tumors (i.

12 Vestibular Schwannoma 34 Neurofibromatosis Type II 35 Guidelines Acoustic Neuroma Associated with neurofibromatosis A genetically-inherited disorder in which the nerve tissue grows tumors (i.e., neurofibromas) that may be benign or may cause serious damage by compressing nerves and other tissues. Bilateral acoustic neuromas (tumors of the vestibulocochlear nerve or cranial nerve 8 (CN VIII) also known as schwannoma ), often leading to hearing loss. In fact, the hallmark of NF 2 is hearing loss due to acoustic neuromas around the age of twenty. Increased Wave I III Interpeak Latency INFORMATIONAL 36 CNIMeKnowledgePlus.net Page 12

13 Guidelines CNIM ONLY Vestibular Schwannoma Surgical Approach-Translabyrinthine Drilling out of mastoid behind the ear Vestibular & Auditory function on side of tumor is sacraficed Auditory nerve & distal portion of tumor are removed Facial nerve is quickly & readily identified at it s distal portion 37 Guidelines CNIM ONLY Middle Fossa Approach Advantages Excellent for intracanalicular tumors, especially at the lateral end of the IAC Hearing preservation is possible Extradural with low risk of CSF leak Disadvantages Lack of access to CPA and posterior fossa Need to retract temporal lobe 38 Guidelines CNIM ONLY Suboccipital /Retrosigmoid Approach Advantages Hearing preservation is possible Access to CPA Disadvantages Limited access to lateral IAC/Fundus Difficult to repairing or grafting CN VII Increased risk of air embolism/csf leak/ post-op headache Cerebellar retraction is necessary* *Increased Wave V CNIMeKnowledgePlus.net Page 13

Guidelines 11 1994 CNIM ONLY Suboccipital Approach Facial nerve is not visualized

monitoring necessary (Retrosigmoid) 40 Guidelines 11 1994 CNIM ONLY APPROACH

SUBOCCIPITAL RETROSIGMOID INTACT NOT VISIBLE IDENTIFIED BY STIMULATION IN THE

14 Guidelines CNIM ONLY Suboccipital Approach Facial nerve is not visualized until tumor is removed Greater risk of facial nerve injury Facial nerve monitoring necessary (Retrosigmoid) 40 Guidelines CNIM ONLY APPROACH HEARING FACIAL NERVE TRANSLABRYNTH SACRIFICED VISABLE MIDDLE FOSSA INTACT VISIBLE SUBOCCIPITAL RETROSIGMOID INTACT NOT VISIBLE IDENTIFIED BY STIMULATION IN THE FIELD 41 THESE NUMBERS DO NOT CORRESPOND TO WAVEFORM NUMBERS!! 42 CNIMeKnowledgePlus.net Page 14

15 Lesion: Cochlear Nucleus 43 Pontine Glioma 44 Midbrain Infarction 45 CNIMeKnowledgePlus.net Page 15

16 Middle Cerebral Artery Infarction affecting the Temporal Lobe 46 Pneumatic Drill & BAEPS 2) Normal or near normal at high intensity click stimulation, but at lower intensity stimulation, Increased absolute Latencies and normal Inter-peak 5) Prolonged Wave V 47 Pneumatic Drill, BAEPS & ARTIFACT 1) High Frequency Noise 2) None. 3) 60 Hz 4) Microphonic 48 CNIMeKnowledgePlus.net Page 16

17 Pneumatic Drill: BAEPS ARTIFACT DATA CHANGE NONE PROLONGED WAVE V 49 1) High Frequency Noise 2) None. 3) 60 Hz Fluorescent Lights Cause 60 Cycle 50 Heschl s Gyrus: Primary Auditory Cortex 1) Cannot assess function with BAEP 2) BAEP only BRAINSTEM & NERVE NO CORTEX 3) No assessment of Thalamus 51 CNIMeKnowledgePlus.net Page 17

18 Cerebellar Retraction in Suboccipital\Retrosigmoid approach: Vestibular Schwannoma: INCREASED WAVE V LATENCY! 52 VIIIth Nerve Stretching Secondary to Cerebellar Retraction in Posterior Fossa Surgery. 53 Cerebellar Retraction in Suboccipital\Retrosigmoid approach: Vestibular Schwannoma 54 CNIMeKnowledgePlus.net Page 18

19 Cochlear Vascular Supply Cochlear branch of the Vestibulo Cochlear Artery Branch of Basilar Artery 55 Guidelines CNIM ONLY Posterior Fossa Surgery BAEP Assess Brainstem Function CRITICAL TO STIMULATE & Cochlear branch of the vestibulo cochlear artery RECORD FROM THE Branch of Basilar Artery CONTRALATERAL SIDE 56 Guidelines CNIM ONLY 3 CM Vestibular Schwannoma- Critical to Monitor: VIII (8 th ) Cranial Nerve Cochlear branch of the vestibulo cochlear artery & Branch of Basilar Artery Facial Nerve 57 CNIMeKnowledgePlus.net Page 19

Brainstem Lesion Causes: Ipsilateral Cranial Nerve Impairment Contralateral Motor Deficit 58 BRAINSTEM & OBLIGATES OBLIGATE LOCATION Cochlear Nucleus Superior Olivary Complex Lateral Lemniscus

20 Brainstem Lesion Causes: Ipsilateral Cranial Nerve Impairment Contralateral Motor Deficit 58 BRAINSTEM & OBLIGATES OBLIGATE LOCATION Cochlear Nucleus Superior Olivary Complex Lateral Lemniscus Inferior Colliculis Spans Junction of Pons & Medulla Extends from the rostral medulla to the mid-pons Pons to Midbrain Midbrain 59 BAEP Clinical Correlates Conductive or Peripheral Hearing Deficit a) Increased Absolute Latencies b) Increased Inter-peak Latency c) IV-V/I Amplitude Ratio d) No change on BAEP 60 CNIMeKnowledgePlus.net Page 20

BAEP Clinical Correlates Sensorineural Hearing Deficit - Cochlear a) Normal or near normal at high

Inter-peak Latencies d) IV-V/I Amplitude Ratio e) No change on BAEP 61 BAEP Clinical Correlates

$d) Increased Absolute Latencies e) Increased IV-V\I Amplitude Ratio 62 BAEP Clinical Correlates$

21 BAEP Clinical Correlates Sensorineural Hearing Deficit - Cochlear a) Normal or near normal at high intensities with increased Absolute Latencies at lower intensities b) Increased Absolute Latencies c) Inter-peak Latencies d) IV-V/I Amplitude Ratio e) No change on BAEP 61 BAEP Clinical Correlates Vestibular Schwannoma -Acoustic Neuroma a) Central Hearing Deficit b) Increased I III c) Increased III-V d) Increased Absolute Latencies e) Increased IV-V\I Amplitude Ratio 62 BAEP Clinical Correlates Vestibular Schwannoma - Acoustic Neuroma BAEP: Increased WI-WIII (WI-V) Most Sensitive: Wave III 63 CNIMeKnowledgePlus.net Page 21

22 BAEP Clinical Correlates Vestibular Schwannoma - Acoustic Neuroma BAEP: Increased WI-WIII (WI-V) 64 BAEP Surgical Correlates If Wave II or Wave IV suddenly disappear during an acoustic neuroma resection, the appropriate action would be: a) Decrease the number of averages b) Do not inform the surgeon of changes c) Inform the surgeon of changes d) Increase the stimulation intensity 65 BAEP Troubleshooting BAEP: ALARM CRITERIA Wave V: > 1 msec or greater 66 CNIMeKnowledgePlus.net Page 22

23 BAEP Troubleshooting If all BAEP WAVEFORMS are lost during the case, however return to baseline by the case close, what is the prognosis for hearing? 67 End Book One SLIDE 68 CNIMeKnowledgePlus.net Page 23

10/2/2017. The Outer Ear THE EXTERNAL AUDITORY MEATUS

10/2/2017. The Outer Ear THE EXTERNAL AUDITORY MEATUS AUDITORY ANATOMY AND HIDDEN CLINICAL VARIABLES Presented by Lawrence R. Wierzbowski AuD DABNM FASNM IONM-P Neurophysiologist & Audiologist Avatrode LLC No Conflict of Interest AUDITORY SYSTEM ANATOMY The