An Imaging Review Sohil Patel MD 1 Casey Halpern MD 2 David Mossa RT 1 Vincent Timpone MD 3 1 NYU Langone Medical Center Dept of Radiology 2 Stanford School of Medicine ID: 774677
Download Presentation The PPT/PDF document " Electrical Stimulation and Monitoring D..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Electrical Stimulation and Monitoring Devices of the CNS: An Imaging Review
Sohil Patel MD1, Casey Halpern MD2, David Mossa RT1, Vincent Timpone MD3
1. NYU-Langone Medical Center, Dept of Radiology2. Stanford School of Medicine, Dept of Neurosurgery3. San Antonio Military Medical Center, Dept of Radiology
ASNR 2015 Electronic Educational Exhibit, #446
Slide2Disclosures
No financial disclosures.
The opinions and views expressed in this presentation are
solely
those of the authors and do not represent an endorsement by or the views of the Department of Defense, or the United States Government.
Slide3Aims
To familiarize the radiologist with various implanted electrical neurological monitoring and stimulator devices, including their:
Clinical indications
Normal components and function
Expected imaging appearance
Potential complications
MRI compatibility
Slide4Content
Subdural and Depth electrodes
Foramen
ovale
electrodes
Deep brain stimulation
Motor cortex stimulator
Responsive
neurostimulation
Middle ear implant
Auditory brainstem implant
Cochlear implant
Vagal nerve stimulator
Spinal stimulator
Slide5Subdural and depth electrodes
Intracranial electrodes placed in epilepsy patients to record brain electrical activity.
Requires craniotomy or burr hole access.
Subdural electrodes
are arranged as a strip or grid array along the surface of the brain.
Depth electrodes
are linear electrodes placed directly into the brain parenchyma
.
Slide6Subdural and depth electrodes
Indications:
Seizure
localization:
Indicated in patients with medically refractory seizures, whose non-invasive tests (
ie
. scalp EEG with video monitoring, MRI) are inconclusive or discordant with respect to seizure
localization/laterality.
Minimization
of surgical resection
Intracranial EEG allows higher spatial and temporal resolution than scalp EEG. This
may allow minimization of the
subsequent surgical resection.
Detection of eloquent cortex
Electrodes can be stimulated to localize nearby eloquent cortex.
MRI compatibility: Safe and conditional devices exist for scanning at 1.5T
Slide7Subdural and depth electrodes
Intracranial EEG monitoring in an 18 year old with partial complex seizures.
Slide8Subdural and depth electrodes
Subdural grid electrodes (short solid arrows).
Slide9Subdural and depth electrodes
Depth electrodes (dashed arrows).
Slide10Subdural and depth electrodes
Wires connecting the intracranial leads to the external EEG recording device (long solid arrows).
Slide11Subdural and depth electrodes
Axial T2WI (right) and T1WI (left) show
subdural electrodes (solid arrows) and
depth electrodes (dashed arrows).
Changes from left temporal-occipital
craniectomy
are noted.
Axial CT, maximum intensity
projection, shows bilateral depth
electrodes (dashed arrows).
Slide12Subdural and depth electrodes
Image from intraoperative
neuronavigation shows the planned trajectory of a depth electrode (solid arrow) into a region of polymicrogyria (dashed arrow).
Intraoperative image from
placement
of a depth electrode
Slide13Foramen ovale electrodes
Intracranial linear electrodes placed to record medial temporal lobe electrical activity.
The electrodes are
inserted via
a trans-facial percutaneous approach with fluoroscopic guidance
.
The electrodes are placed into the ambient cisterns, adjacent to the medial temporal lobes.
Slide14Foramen ovale electrodes
Indicated in patients
with suspected medial temporal lobe
epilepsy, but with unconfirmed localization/laterality based on non-invasive testing.
Foramen
ovale
electrodes provide higher spatial and temporal resolution than scalp EEG.
Compared to subdural/depth electrodes, foramen
ovale
electrodes:
Do not require craniotomy/burr hole.
Are not placed into brain parenchyma.
Evaluate only medial temporal lobes
.
MRI compatibility: Safe and conditional devices exist for scanning at 1.5T
Slide15Intraoperative radiographs show the normal positioning of bilateral foramen
ovale
electrodes (arrows). Both electrodes have 4 contact points.
Slide16Axial CT scan image shows foramen
ovale
electrodes in the ambient cisterns, adjacent to the medial temporal lobes (solid arrows).
Coronal CT scan images show the
electrodes traversing
bilateral foramen
ovale
(dashed arrows).
Foramen
ovale
electrodes
Slide17Deep brain stimulation (DBS)
Intracranial electrodes that produce electrical stimulation of functional targets in the brain parenchyma.
DBS electrodes are placed via burr holes or craniotomy. Guided to targets using image-guided
neuronavigation
and neurophysiologic recording.
FDA approval for treatment of essential tremor,
parkinson’s
disease, primary dystonia, obsessive compulsive disorder.
Off-label use in the treatment of refractory depression, chronic pain, epilepsy, and Tourette syndrome
.
MRI compatibility:
Conditional devices exist for scanning at 1.5T
Slide18Deep brain stimulation
Targets
Parkinson’s Disease
Subthalamic
nucleus
Globus
pallidus
internus
Essential Tremor
Ventral intermediate nucleus of the thalamus
Primary dystonia
Globus
pallidus
internus
Obsessive compulsive disorder
Internal capsule anterior limb
Subthalamic
nucleus
Slide19Deep brain stimulation
Bilateral DBS in a 78 year old male with Parkinson’s disease.
Slide20Deep brain stimulation
The components of the DBS system include the intracranial leads (solid short arrows) which
contain 4 electrode contacts at their distal tips (arrowheads).
Slide21Deep brain stimulation
The intracranial electrodes are connected, via extension wires (long solid arrows), to the pulse
g
enerators (dashed arrows) which are implanted subcutaneously in the chest wall.
Slide22Deep brain stimulation
Coronal T1WI shows bilateral DBS electrodes terminating in the
subthalamic nuclei (arrows) in this patient with Parkinson’s disease.
Slide23Deep brain stimulation
Axial and coronal T1WI show bilateral DBS electrodes (arrows) within the globus pallidus internus in this 64 year old female with dystonia.
Slide24Deep brain stimulation
Off-label use for the treatment of epilepsy. Targets include hippocampus/amygdala and the thalamus.In medial temporal lobe epilepsy, DBS indicated if patients are:Refractory to medical treatmentUnsuitable for surgical therapy due to:Bilateral diseaseSurgical risk of major verbal memory loss (assessed with intraarterial amobarbital testing).
Temporal lobe stimulators in a patient
with intractable epilepsy. Electrodes
(arrows) lie within the medial temporal lobes.
Slide25Motor cortex stimulator
Used in patients with refractory pain syndromes.
Strip electrodes are placed in the epidural space overlying the motor cortex via craniotomy approach.
The motor cortical representation of the painful site is targeted (
ie
. contralateral to side of pain). The electrodes are guided to the appropriate location using image-guided
neuronavigation
and intraoperative neurophysiologic testing.
After appropriate positioning, the lead is sutured to the
dura
, and connected via extension wiring to a pulse generator that is implanted in the chest wall subcutaneous tissues
.
Slide26Motor cortex stimulator
Variable success in the treatment of a variety
of
pain
syndromes,
including
Trigeminal neuralgia
Post-stroke pain
Phantom
limb
pain
H
erpetic neuralgia
Multiple sclerosis.
Usage is off-label
.
MRI compatibility
:
Unknown.
Slide27Motor cortex stimulator
Lateral scout radiograph shows a 4-contact motor cortex electrode (solid arrow). The intracranial lead is connected to a pulse generator (not shown) via extension wiring (arrowhead) that is tunneled through the neck subcutaneous tissue.
Axial CT images from the same patient show the intracranial lead (solid arrow)
within the epidural space overlying the left motor strip (dashed arrow).
Slide28Responsive Neurostimulation
FDA approved for the treatment of medication refractory partial onset seizures in adults.
The responsive
neurostimulator
device records
and processes EEG
data from targeted brain regions.
It delivers electrical stimulation
to these targets upon
detection of seizure activity
. The electrical stimulation disrupts the seizure activity.
The
neurostimulator
cassette (containing the pulse generator) is implanted in the
calvarium
.
The
neurostimulator
is connected to either cortical strip leads (which are placed on the brain surface) or depth leads (which are placed in the brain parenchyma).
Slide29Responsive Neurostimulation
Shown
to lower seizures rates
by 50
% on average. The therapeutic efficacy might increase over time via
neuromodulatory
effects.
Compared to surgical
therapy:
Different sites (up to two) can be targeted.
Eloquent regions can be targeted without disruption
Reversible (the device can be removed).
Compared with DBS:
Responsive
neurostimulation
does not provide continuous stimulation. Rather, it is “triggered” by the detection of seizure activity
.
MRI compatibility: Not MRI compatible
.
Slide30Responsive Neurostimulation
Scout radiographs and axial CT images show an implanted Responsive
Neurostimulator
device in a 24 year old female with medication resistant partial complex seizures.
Slide31Responsive Neurostimulation
The
neurostimulator cassette (solid arrows) has been implanted within a parietotemporal craniectomy bed. Neurostimulator cassette within a skull model (dashed arrow) for comparison.
Slide32Responsive Neurostimulation
Four electrodes were implanted (arrows
). Intraoperative electrocorticography was performed from each electrode. The neurostimulator was connected to two of the electrodes which recorded the greatest seizure activity. The remaining two electrodes were left in place but were not connected to the neurostimulator.
Slide33Middle Ear Implant
Electronic device that converts sound energy into mechanical vibrations that directly stimulate middle ear structures.
Externally worn audioprocessor receives and transmits signal to vibrating ossicular prosthesis embedded subcutaneously overlying the temporal bone.
Vibrating
ossicular
prosthesis transmits signal to middle ear transducer which is attached to
incus
or round window and causes these structures to vibrate and amplify acoustic input to cochlea.
Slide34Middle Ear Implant
Indications: Moderate to severe
sensorineural
hearing loss in patients with suboptimal response to traditional hearing aid devices, or medical contraindication to such devices (
ie
otitis
externa
).
Compared to conventional external hearing aid devices:
Similar hearing thresholds
Improved sound quality, less feedback
Improved comfort and patient satisfaction
Potential complications: Bleeding, infections, facial nerve injury.
MR compatibility: No current MR compatible devices available.
Slide35Middle Ear Implant
36
yo
female with mixed hearing loss. Vibrating ossicular prosthesis implanted under the skin (solid arrow) receives input from an externally worn audioprocessor (not shown) and transfers signal to a vibrating middle ear transducer (dashed arrow).
Slide36Middle Ear Implant
CT images from same patient demonstrating subcutaneous vibrating
ossicular
prosthesis (solid arrow), electrode (arrowhead), and transducer (dashed arrow) implanted adjacent to the round window. In patients with normal ossicles, transducer may be attached to the incus.
Slide37Cochlear Implant
Implanted electronic hearing device converting sound
energey
into
electronic impulses that directly stimulate the cochlea.
Sound signal detected by an external microphone and
audioprocessor
.
Audioprocessor
is magnetically attached to an implanted receiver-stimulator seated within the temporal bone.
Receiver-stimulator converts signal transmitted from
audioprocessor
into electrical impulses that stimulate the cochlea via a soft flexible electrode array.
Slide38Cochlear Implant
Indications: Severe to profound
sensorineural
hearing loss.
Majority of patients demonstrate significant improvement in measurements of speech recognition though results vary based on age at implantation and duration of hearing loss.
Several studies suggest improved functional outcome with greater insertion depth and when electrode located in the
scala
tympani.
Cochlea coordinate system developed by consensus panel in 2010 and enables viewers to communicate implant array location with less ambiguity.
Potential complications:
Facial
nerve injury, CSF leak, loss of residual hearing.
MR compatibility: MR conditional devices available.
Slide39Cochlear Implant
40
yo female with bilateral sensorineural hearing loss treated with bilateral cochlear implants. Receiver-stimulators (solid arrows) are embedded to the temporal bone. Flexible array electrodes (dashed arrows) are seen coiled within the cochlea, approximately 360 degrees on the right, 180 degrees on the left.
Slide40Cochlear Implant
CT images from same patient demonstrating electrodes coiled within the cochlea, with electrode tips visualized (solid arrow). Using standardized cochlear coordinate
system,
electrode tips are positioned at approximately segment 5 on the right, segment 3 on the left.
Slide41Auditory Brainstem Implant
Electronic device which stimulates cochlear nucleus directly and provides sound sensation to an otherwise deaf patient.
Paddle array electrode placed in lateral recess of 4
th
ventricle overlying dorsal-lateral surface of cochlear nucleus.
Electrode connects to receiver-transmitter seated within the temporal bone.
Sound picked up by microphone at
pinna
, signal then sent to pocket sized speech processor worn on the patient.
Speech processor changes sound signal to an electronic impulse sent to the receiver through a transmitter coil.
Slide42Auditory Brainstem Implant
Indications: Patients without functioning cochlea or cochlear nerve, but with intact auditory brainstem pathway:
Bilateral vestibular
schwannomas
in Neurofibromatosis II
Skull-base
trauma with cochlea damage
Congenitally absent
cochlear
nerve
In clinical studies, >80% of patients able to detect familiar sounds (
ie
doorbell, honking horn) and demonstrate improved understanding of conversation with aid of
lip-reading
.
Potential complications:
Non-auditory
stimulation of other cranial nerves if electrode placed
too far ventrally
MR Compatibility: MR conditional devices available.
Slide43Auditory Brainstem Implant
A. Demonstrates the receiver-stimulator component that has a grounding electrode embedded underneath temporalis muscle, and multichannel electrode paddle inserted into the 4
th
ventricle lateral recess. B. External components include microphone which sends sound to processor-digitizer which in turn sends electrical impulses to the receiver via the transmitter coil.
Lekovic
et al: Auditory Brainstem Implantation
Slide44Auditory Brainstem Implant
Auditory brainstem implant in 25
yo
male with Neurofibromatosis type 2 and bilateral
sensorineural hearing loss. Receiver-stimulator embedded within the temporal bone (solid arrow) connected to electrode paddle (dashed arrow) located in the 4th ventricular lateral recess, abutting the dorsal lateral surface of the cochlear nucleus.
Slide45Vagal Nerve Stimulator
Stimulation of
vagal
cervical trunk to treat wide variety of disorders, most commonly medically refractory epilepsy and depression.
Small electrode implanted around the left
vagus
nerve cervical
trunk, approximately 8cm above the clavicle and connected to a programmable generator placed subcutaneously in the upper thorax.
Mechanism of action not fully
understood,
however afferent vagal fiber activation appears to disrupt seizure-related circuitry.
Vagal nerve stimulation may also alter neurotransmitter and metabolite concentrations leading to antidepressant effects.
Slide46Vagal Nerve Stimulator
Right sided
vagus
nerve stimulation thought to result in increased cardiac
side effects
. Only left sided
vagus
nerve stimulators currently FDA approved.
In clinical studies:
Greater than 50% reduction in seizure frequency, as well as reduced seizure duration and
post-
ictal
recovery
times.
Greater than 50% reduction in depression scores after 12 months of therapy.
Potential complications:
vocal
cord paresis, dysphagia.
MR compatibility: MR conditional devices available.
Slide47Vagal Nerve Stimulator
53
yo
with
epilepsy treated with vagal nerve stimulation. Subcutaneous pulse generator (solid arrow) is seen in the upper left thorax and is connected to a coiled electrode (dashed arrow) attached to the left cervical vagus trunk.
Slide48Spinal Cord Stimulator
Electronic device which stimulates posterior columns of spinal cord in treatment of chronic pain.
With stimulation patient will feel mild
paresthesias
in their area of pain, which inhibits transmission of other
nociceptive
inputs, reducing overall level of pain.
3 components:
Generator: implanted
under the skin
and sends
electrical impulses to electrodes.
Electrodes:
inserted into the posterior epidural space and threaded
to
the desired
level under fluoroscopic guidance.
Wireless programmable
controller:
regulates stimulation.
Slide49Spinal Cord Stimulator
Indications:
Treatment resistant chronic back/extremity pain.
Failed back surgery syndrome
In selected patients,
spinal cord stimulation more effective and less expensive than reoperation for treatment of persistent
post-operative
radicular pain.
Potential complications:
CSF
leak.
MR compatibility: MR conditional devices available.
Slide50Spinal Cord Stimulator
64
yo
female with chronic cervicalga. Subcutaneous pulse generator (solid arrow) is seen in the left lower flank, connected to 2 leads each with 4 electrode contact points at their distal tip in the cervical spine (dashed arrow).
Slide51Spinal Cord Stimulator
CT images from same patient demonstrate the desired posterior epidural placement of the electrodes (dashed arrows).
Slide52Complications of implanting neurologic stimulators/monitoring devices
Infection
Hemorrhage
Infarction
Vascular
injury
Device
malpositioning
Lead fracture
Lead disconnection
Slide53Complications - infection
21 year old female with complex partial
seizures. Intracranial EEG recording with
subdural grid (solid arrows) and depth electrodes (dashed arrows) was undertaken.
Slide54Complications - infection
The patient returned to emergency department 2 months after the electrodes were removed, complaining of swelling and discharge near the craniotomy site. When compared to the axial CT image with intracranial electrodes in place (left image), the axial CT image 2 months later (right image) shows new erosions (arrowheads) in the bone flap. At surgical pathology, this proved to represent osteomyelitis of the bone flap.
Slide55References
1.Ben-Menachem
E, Krauss GL: Epilepsy: responsive
neurostimulation
-modulating the epileptic brain.
Nature reviews Neurology
2014, 10(5):247-248.
2.Blount
JP, Cormier J, Kim H,
Kankirawatana
P, Riley KO, Knowlton RC: Advances in intracranial monitoring.
Neurosurgical focus
2008, 25(3):E18.
3.Boex
C,
Seeck
M,
Vulliemoz
S, Rossetti AO,
Staedler
C,
Spinelli
L,
Pegna
AJ,
Pralong
E,
Villemure
JG,
Foletti
G
et al
: Chronic deep brain stimulation in mesial temporal lobe epilepsy.
Seizure
2011, 20(6):485-490.
4.Carmichael
DW, Thornton JS,
Rodionov
R, Thornton R,
McEvoy
A, Allen PJ, Lemieux L: Safety of localizing epilepsy monitoring intracranial electroencephalograph electrodes using MRI: radiofrequency-induced heating.
Journal of magnetic resonance imaging : JMRI
2008, 28(5):1233-1244.
5.Chen
XL,
Xiong
YY,
Xu
GL, Liu XF: Deep brain stimulation.
Interventional neurology
2013, 1(3-4):200-212.
6.Cox
JH, Seri S,
Cavanna
AE: Clinical utility of implantable
neurostimulation
devices as adjunctive treatment of uncontrolled seizures.
Neuropsychiatric disease and treatment
2014, 10:2191-2200.
7.Davis
LM, Spencer DD, Spencer SS,
Bronen
RA: MR imaging of implanted depth and subdural electrodes: is it safe?
Epilepsy research
1999, 35(2):95-98.
8.Fisher
RS, Velasco AL: Electrical brain stimulation for epilepsy.
Nature reviews Neurology
2014, 10(5):261-270.
9.Heck
CN, King-Stephens D, Massey AD, Nair DR,
Jobst
BC, Barkley GL,
Salanova
V, Cole AJ, Smith MC, Gwinn RP
et al
: Two-year seizure reduction in adults with medically intractable partial onset epilepsy treated with responsive
neurostimulation
: final results of the RNS System Pivotal trial.
Epilepsia
2014, 55(3):432-441.
10.Henderson
JM, Lad SP: Motor cortex stimulation and neuropathic facial pain.
Neurosurgical focus
2006, 21(6):E6.
Slide56References
11.Jenkins HA,
Uhler
K:
Otologics
Active Middle Ear Implants.
Otolaryngologic
clinics of North America 2014, 47(6):967-978.
12.Lefaucheur JP,
Drouot
X,
Cunin
P,
Bruckert
R,
Lepetit
H,
Creange
A,
Wolkenstein
P,
Maison
P,
Keravel
Y, Nguyen JP: Motor cortex stimulation for the treatment of refractory peripheral neuropathic pain. Brain : a journal of neurology 2009, 132(
Pt
6):1463-1471.
13.Merkus P, Di
Lella
F, Di Trapani G,
Pasanisi
E,
Beltrame
MA,
Zanetti
D,
Negri
M,
Sanna
M: Indications and contraindications of auditory brainstem implants: systematic review and illustrative cases. European archives of
oto
-rhino-laryngology : official journal of the European Federation of
Oto
-Rhino-Laryngological Societies 2014, 271(1):3-13.
14.Morrell MJ, Group
RNSSiES
: Responsive cortical stimulation for the treatment of medically intractable partial epilepsy. Neurology 2011, 77(13):1295-1304.
15.Rushton DN: Electrical stimulation in the treatment of pain. Disability and rehabilitation 2002, 24(8):407-415.
16.Sheth SA, Aronson JP,
Shafi
MM, Phillips HW, Velez-Ruiz N, Walcott BP, Kwon CS,
Mian
MK, Dykstra AR, Cole A et al: Utility of foramen
ovale
electrodes in mesial temporal lobe epilepsy.
Epilepsia
2014, 55(5):713-724.
17.Yang AI, Wang X, Doyle WK,
Halgren
E, Carlson C, Belcher TL, Cash SS,
Devinsky
O,
Thesen
T: Localization of dense intracranial electrode arrays using magnetic resonance imaging.
NeuroImage
2012, 63(1):157-165.
18.Yuan J, Chen Y, Hirsch E: Intracranial electrodes in the
presurgical
evaluation of epilepsy. Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology 2012, 33(4):723-729.
19.
Verbist
BM, Skinner MW, Cohen LT, et al. Consensus panel on a cochlear coordinate system applicable in histologic, physiologic, and radiologic studies of the human cochlea.
Otol
Neurotol
2010;31:722–30
20.Beltrame AM, Martini A, Prosser S,
Giarbini
N,
Streitberger
C. Coupling the Vibrant
Soundbridge
to cochlea round window: auditory results in patients with mixed hearing loss.
Otol
Neurotol
. 2009 Feb;30(2):194-201.
Slide57References
21.
Kahue
CN, Carlson ML, Daugherty JA, Haynes DS, Glasscock ME 3rd. Middle ear implants for rehabilitation of
sensorineural
hearing loss: a systematic review of FDA approved devices.
Otol
Neurotol
. 2014 Aug;35(7):1228-37
22. Finley CC, Holden TA, Holden LK, et al. Role of electrode placement as a contributor to variability in cochlear implant outcomes.
Otol
Neurotol
2008;29:920–28
23. Colby CC, Todd NW,
Harnsberger
HR, Hudgins PA. Standardization of CT Depiction of Cochlear Implant Insertion Depth. AJNR. 2015 Feb;36(2):368-71
24.
Manchikanti
, L, Boswell MV, et al. Comprehensive review of therapeutic interventions in managing chronic spinal pain. Pain Physician. 2009 Jul-Aug;12(4):E123-98.
25. Kumar K, Taylor RS, Jacques L et al. Spinal cord stimulation versus conventional medical management for neuropathic pain: a
multicentre
randomised
controlled trial in patients with failed back surgery syndrome. Pain 2007;132:179-188.
26.
Lekovic
G, Gonzalez F,
Syms
M,
Daspit
C, Porter R. Auditory
Braintstem
Implantation. Barrow quarterly
vol
(20) no 4 2004.
27.
Ghaemi
K,
Elsharkawy
AE, Schulz R et al.
Vagus
nerve stimulation: outcome and predictors of seizure freedom in long-term follow-up. Seizure 2010; 19:264–268.
28.
Beekwilder
JP,
Beems
T. Overview of the clinical applications of
vagus
nerve stimulation. J
Clin
Neurophysiol
. 2010 Apr;27(2):130-8.
29. www.fda.gov