Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download MONITORING OPERATIONS IN THE SKULL BASE
Document related concepts
Transcript
MONITORING OPERATIONS IN THE SKULL BASE CHAPTER VI Monitoring of cranial nerves in skull base operations: what to monitor? 1. Extraocular muscles 2. Facial muscles 3. Masseter muscle 4. Tongue 5. CNIX pharynx 6. CNX larynx 7. ABR 8. CAP from CNVIII and cochlear nucleus Monitoring other cranial motor nerves Extraocular muscles • CN III • CN IV • CN VI Lower cranial nerves • CN IX • CN X • CN XI • CN XII Monitoring other cranial motor nerves • Monitoring the facial nerve is a model for monitoring other cranial motor nerves How to activate the motor system? • • • • Electrical stimulation of motor nerves Magnetic stimulation of motor nerves Electrical stimulation of the motor cortex Magnetic stimulation of the motor cortex How to record the response? • Recording of electromyographic (EMG) potentials • Mechanical recordings of muscle contractions • Recording of motor nerve CAP Recording of EMG potentials Recording muscle responses • Muscle relaxants cannot be used MONITORING OTHER CRANIAL MOTOR NERVES EXTRAOCULAR MUSCLES • CN III • CNVI • CNIV LOWER CRANIAL NERVES • CNIX • CNX • CNXI • CNXII Monitoring nerves that innervate extraocular muscles CN III, CN IV, CN VI Recording EMG potentials from extraocular muscles • Using needle electrodes Recording from extraocular muscles: Place needle electrodes percutaneously so they come close to respective muscles Medial rectus for CNIII Lateral rectus for CNVI Superior oblique for CNIV EMG potentials recorded from extraocular muscles in response to electrical stimulation of respective cranial nerves intracranially Recording EMG potentials from extraocular muscles • Using non-invasive electrodes Electrical stimulation of the oculomotor nerve (CN III) Middle rectus Lateral rectus Masseter Monitoring multiple systems simultaneously • • • • • • • Extraocular muscles Facial muscles Masseter muscle Tongue Neck muscles BAEP VEP Typical placements of recording electrodes used in skull base operations Recording from extraocular muscles: Place needle electrodes percutaneously so they come close to respective muscles Medial rectus for CNIII Lateral rectus for CNVI Superior oblique for CNIV Monitoring other cranial motor nerves Lower cranial motor nerves CN IX, CN X, CN XI, CN XII FROM YINGLING Monitoring CN X can be done by placing recording electrodes in the vocal folds Monitoring CNX FROM YINGLING FROM YINGLING Auditory neuromonitoring Recording of auditory evoked potentials in operations in the posterior fossa Monitoring of ABR can detect manipulations of the brainstem before cardiovascular signs change Waveform analysis of the ABR provides information about the anatomical location of an injury Different conventions for display of BAEP NEURAL GENERATORS OF THE ABR: • Peak I: distal auditory nerve • Peak II: central auditory nerve • Peak III: mainly cochlear nucleus • Peak IV: unknown • Peak V: termination of the lateral lemniscus in the contralateral inferior colliculus Ipsilateral stimulation Waveform analysis of the BAEP provides information about the anatomical location of an injury PEAK V PEAK III Contralateral stimulation Waveform analysis of the BAEP provides information about the anatomical location of an injury PEAK V PEAK III
