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Brain Stem Motor Mapping
Dachling Pang, MD, FRCS(C), FRCS(Eng), FACS
Professor of Paediatric Neurosurgery
University of California, Davis
Chief, Regional Centre for Paediatric Neurosurgery
Kaiser Permanente Hospitals
Northern California
Surface Anatomy and Projected Nuclei
of the 4th Vent. Floor
Colliculus sup.
Motor nuc. N.V Brachium pontis
Cochlear nucleus
Main sensory nuc. N.V
Commissural nucleus
Nuc. N.III
Vestibular nucleus
Nuc. N.IV
Spinal nuc. N.V
Nuc. sal. Inf.
Med. geniculate body
Mesencephalic nuc. N.V
Nuc. N.XII
Facial colliculus
Dorsal motor nuc. N.X
Colliculus inf.
Motor nuc. N.VII
Trigonum hypoglossi
Nuc. sal. sup.
Nucleus of Edinger-Westphal
Nuc. of tractus solitarius
Nuc. ambiguus
Nuc. N.VI
Inside the Facial Colliculus
Motor nucleus n.V
Abducens nerve
Internal genu of facial nerveNucleus of oculomotor nerve
Facial nerve
Nucleus of Edinger-Westphal
Facial nerve
Abducens nucleusOculomotor nerve
Portio minor N.V
Facial nerve
Trochlear nerve
Central canal
Nucleus of hypoglossi nerveDorsal motor nucleus N.V
Nucleus of abducens nerve
Nucleus ambiguus
Abducens nerve
Nucleus of trochlear nerve
Nuc. Salivatorius inferior
Nuc. salivatorius superior
Nucleus of facial nerve
Anterior medullary velumFacial nucleus
Brain Stem Motor Mapping
4th Ventricular Floor Amenable to Direct Stimulation
of Several Cranial Nerve Nuclei
1. Best is the Internal Genu of the Facial nerve and adjacent Abducens Nucleus
2. Hypoglossal Trigone with Tongue Needle EMG Electrodes - caution : tongue swelling and bradycardia due to adjacent vagal nucleus
3. Nucleus Ambiguus with Laryngeal EMG Electrodes affixed to ET tube
4. Trigeminal Motor Nucleus - less reliable
Lateral Rectus (VI);
Levator Ang. Oris (VII);
Masseter (V)
Trapezius (XI)
V Nerve Responses: Smaller & seldom pure
3 ms/Div
Trigger EMG's
3 ms/Div20 µV/Div
CN VI
CN V
CN VII
CN XI
Laryngeal Electrode: Position on ET Tube and
Location Against Vocal Cords
Position on ET Tube Located
against vocal
cords
Different sizes
Bilateral Vocal Cord Electrodes Incorporated within ET Tube
Right Set
Left Set
Vocal Cords
Paired 25-Gauge Needle Electrodes for the Tongue
Evoked Potentials on XII Nerve Hypoglossal Trigone Stimulation :
Often Bilateral
5 ms/Div50 µV/Div
L VI - 14µV
L VII - 4µV
L XI - 96µV
Trigger EMG's
5 ms/Div50 µV/Div
R VI - 8µV
R VII - 5µV
R XI - 21µV
L VI R VI
L VII R VII
L XII R XII
Complication with Needle
Electrodes in the Tongue :
Swollen & Haemorrhagic Tongue
Requiring Tracheostomy
Hooked Wire Electrodes withApplicators
CannulaHooked wire
Green SiliconeBand
Dual Platinum-iridium wires inserted into Cannula with tips curved outwards, fixed by a Silicone Band.
Wires remain in tissue after insertion & pulling out Cannula.
Hooked wires remain in tissue
Flexible GuideTube for Cannula
Guide Tube Cannula
Applicator
Cannula containing Hooked
Wires is placed into Flexible
Guide Tube, which is then
inserted into Hand-held
Applicator.
Aim Applicator tip at target
muscle, then press forth base
of Cannula.
Hooked Wires from Dubrovnik
Somatosensory Evoked
Potential
Brain Stem Auditory
Evoked Potential
Facial Colliculus Mapping3 yr. boy, 6 wks of left 6th nerve palsy; normal 7th
Transvermal Approach to 4th Ventricle
Hump at L facial colliculus, deviated median raphe; caudally shifted L striae medullares.Surgeon’s instinct is to biopsy the Hump
med. raphes.m.
Concentric Coaxial Stimulator
+
-
insulator
Patterns of Current Spread in 3 Different Stimulating Electrode Types
Monopolar Electrode Two-Prong
Bipolar Electrode
Concentric
Coaxial Electrode
Very focal
current spread
Transvermal Approach and Facial Colliculus Stimulation
Right facial
colliculus(0.5 ma)
Peak of
left facial
hump(0.5 ma)
Left
“anatomic”
facial
colliculus(0.5 ma)
Perimetry
of left
facial
hump(0.5 ma)
Responsivity Map of Left Facial Nerve
1030
50
80
100
Check biopsy site with Stealth
Stealth Stereotactic Localization of Biopsy Site
Tumour Biopsy
Post-op MR Showing Actual Biopsy Site
Normal Left Facial Movement 2 days Post-op
06-4386
Low Grade Glioma
Monitoring For Spontaneous
Firing (“Injury Potentials”)
of Motor Cranial Nerves
III, V, VI, VII, XI, XII Nerves
Pontomesencephalic Peduncular Tumour :7 Yr. Boy, Right Hemiparesis - “Spastic CP”
Pontomesencephalic Peduncular Tumour :Subtemporal Transpeduncular Approach
Subtemporal Transpeduncular Approach – Tentorium Exposed
Tentorial Edge
IV Nerve
Subtemporal Transpeduncular Approach – 4th Nerve Found
IV Nerve
PeduncleCut TentorialEdge
Subtemporal Transpeduncular Approach – Tentorium Cut
IV NerveCut tentorialEdge
Peduncle
Subtemporal Transpeduncular Approach – Biopsy Tumour
IV Nerve
Tumour
Peduncle
Subtemporal Transpeduncular Approach – Soft Grey Tumour
Subtemporal Transpeduncular Approach – CUSA Tumour
Subtemporal Transpeduncular Approach – Med Rectus Flutter
Subtemporal Transpeduncular Approach – Clean Tumour Bed
IV Nerve
Subtemporal Transpeduncular Approach – Gross Total Resection
Post Cerebral Artery
IV Nerve
Subtemporal Transpeduncular Approach – Post Cerebral Artery
tcMEP; SSEP;
& Third Nerve
Monitoring
med rectusflutter
med rectusflutter
Pontomesencephalic Peduncular Tumour :Subtemporal Transpeduncular Approach
Basic Monitoring Techniques
Auditory Brainstem Response (ABR)
Somatosensory Evoked Potentials (SEP)
Somatosensory Evoked
Potentials (SEP)
Brain Stem Auditory
Evoked Potentials (ABR) Ear Plug
Cerebellar JPA9 Yr. old girl, headache, vomiting, R dysmetria
Sudden Lost of Right ABRs (All Waves)
During Tumour Resection
120
90
60
30
15:25:28
Mi
nu
te
s
1 ms/Div0.3 µV/Div
L ABR - Waterfall - A1-CZ
120
90
60
30
15:26:09
Mi
nu
te
s
1 ms/Div0.3 µV/Div
R ABR - Waterfall - A2-CZLeft ABR Right ABR
Wave V
No Changes in Other Parameters :Normal Upper SEPs
150
112:30
75
37:30
15:42:06
Mi
nu
te
s
5 ms/Div0.7 µV/Div
Lt Upper SEP - Waterfall - C4'-C3'
150
112:30
75
37:30
15:42:19
Mi
nu
te
s
5 ms/Div0.7 µV/Div
Rt Upper SEP - Waterfall - C3'-C4'Right UE SEPLeft UE SEP
Checked ABR ear plug and connections :
All in order
ABR returned to normal after huge ear wax removed and ear plug replaced
Right ABRs Completely Recovered After
Ear Wax Removed
120
90
60
30
15:25:28
Mi
nu
te
s
1 ms/Div0.3 µV/Div
L ABR - Waterfall - A1-CZ
120
90
60
30
15:26:09
Mi
nu
te
s
1 ms/Div0.3 µV/Div
R ABR - Waterfall - A2-CZLeft ABR Right ABR