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