Dr. Ho

Question 1

What is neuroprosthesis? What are two other names for this approach?

Answer 1

type of medical device that helps restore lost (peripheral) body functions by directly interacting with the nervous system

also called functional electrical stimulation (FES) or functional neuromuscular stimulation (FNS)

electronic device that uses electrical signals to “replace” or support damaged nerve functions.

Question 2

Neuroprostheses can restore what?

Answer 2

some motor, sensory, and autonomic functions by stimulation various parts of the nervous system including muscles, nerves, spinal cord, or the brain

Question 3

How do neruoprosthetics work GENERALLY?

What are benefits of neuroprostheses?

Answer 3

when the NS is damage, communication between the brain and body is disrupted. Neuroprosthesis either

bypass or replace these damaged signals

electrically stimulate intact nerves or muscles

Benefits:
Neuroprostheses employing FES to control the paralyzed muscles can postpone or prevent many secondary medical complications and improve functional independence by providing a means to exercise and negotiate physical barriers

Question 4

What are basic components of functional electrical stimulation (FES)?

Answer 4

power supplies - external or implanted

control circuit (brains of the device)

lead wires, connectors

electrodes

sensors

Question 5

What are some basic properties of electrodes for FES?

How can charge flow into tissue?

Can this work with denervated nerves/muscles?

Nerve stim vs muscle stim

Answer 5

Electrodes act as the interface between external electronics and body tissue, and as a conductor, delivering electrical charge from a power source to tissue

When voltage is applied between active electrode and reference electrode, an electric field is created, allowing charge to flow into the tissue

Target nerves/muscles must NOT be denervated (they need to still be functional)

nerve stim vs muscle stim: nerves require lower charge density, and muscles require higher charge density

Therefore, stimulating nerves is more efficient, uses less power, and reduces risk of tissue damage

Question 6

What is an overall trend you can deduce based on the different methods?

Answer 6

Trend: closer to neurons = more precise control, but also more invasive

Question 7

Describe surface FES devices

Answer 7

electrodes are placed over skin surface to stimulate motor points

Advantages: no surgery, easy to apply and replace

Disadvantages: less precise (current spreads), harder to position accurately, must reapply each time

Question 8

Describe implanted FES devices

Answer 8

electrodes placed inside the body (near nerves, muscles, or spinal cord)

Advantages: highly targeted stim, req lower current, efficient and controlled

Disadvantages: req surgery, risk of infection, long-term foreign body concerns, harder to replace

Question 9

What are some clinical conditions where there are disruptions in the nervous system, where there is an intact target pathway for stimulation for neuroprostheses?

Answer 9

hearing loss: cochlear implants stimulate auditory nerve

spinal cord injury: bypass damaged communication pathways

stroke: restore motor control

Question 10

About how many people with SCI in Canada?

About how many Albertans with SCI?

What are the most common causes

Mostly affects who?

Answer 10

About 86 000 with SCI in Canada

About 5 200 Albertans with SCI

common causes: motor vehicle accidents, sports, falls, violence

Mostly affects young adults and older adults

Question 11

A SCI disrupts what?

Answer 11

Efferent pathways (brain to body AKA motor signals)

Afferent pathways (body to brain AKA sensory signals)

Insight: CNS is damaged, but PNS is still intact, which is why neuroprosthesis (FES) is useful, because they can bypass damaged pathways and activate intact muscles/nerves

Question 12

Loss of motor, sensory, and autonomic functions occurs below the level of injury, leading to

Answer 12

motor weakness or paralysis

sensory impairment

autonomic:
bowel and bladder dysfunction
sexual dysfunction

Question 13

Neuroprostheses (FES) can restore what because muscles and nerves are still viable?

Answer 13

upper limb (arms/hands)
lower limbs (walking/gait)
trunk stability and posture
breathing (respiratory muscles)
bladder control
pressure injury prevention

Question 14

There is a way to regain hand and arm function after C5/C6 level SCI.

Muscle contractions can be orchestrated to produce:

This can be coupled with what to maximize function

Answer 14

handgrip
hold and release relatively cylindrical objects
lateral gripping for thin and smaller objects

can be coupled with tendon transfer surgery to maximize function

Question 15

FES for upper extremity functional restoration

What is an example of surface stimulation device?

Implanted device?

Answer 15

Surface stim
Bionic glove, Prochazka et al, 1997
MyndMove (MyndTec)

Implanted device
Freehand System (Peckham et al, 2001)

Question 16

Describe BIONIC GLOVE

Answer 16

surface stim

electrodes placed on motor point (hand and forearm)
glove without fingers + extension as forearm
stim triggered by movements which are detected by a sensor in the handle.

Extension of the handle, beyond a certain angle, causes gripping movement

flexion of handle causes opening of the hand

Long term effect: improved grip stretch, reduced time to perform functional activities

Question 17

Describe FREEHAND SYSTEM

Answer 17

fully implanted FES

stimulator implanted in chest wall
electrodes implanted on motor points of arm and hand muscles

for people with C5 complete injury

controlled by contralateral shoulder movement
shoulder motion sends signals to open hand and close hand (grasp)

restores grasp and release, ability to hold objects

implanted in 200 persons with SCI
no longer marketed by company

*alternative body movements (like the shoulder) controls the hand

Question 18

Describe MyndMove

Answer 18

surface stim

multichannel system using one stimulator

surface electrodes along upper extremity can generate complex functional movements (holding something, bringing hand to mouth, reaching side, forward)

Question 19

Describe FES for lower extremity restoration (surface and implanted) + their associated machinery

Answer 19

Surface/non-invasive
used for foot drop (difficulty lifting foot while walking) by causing ankle dorsiflexion when sensors are triggered
bioness L300 and Walkaide
FES cycling also promotes exercise and muscle conditioning

implanted neuroprostheses (invasive)
used for more severe injuries like thoracic SCI
works by stimulating contractions of lower extremity muscles enabling standing and stepping
8+ stimulation channels to knee, hip, trunk extensors can enable sit to stand, maintain upright posture, support stepping

Question 20

For persons with incomplete SCI, what can have a therapeutic effect to improve strength, walking speed, stride length and cadence?

Answer 20

gait training with FES

Question 21

Truncal muscles are often weak after SCI, not providing sufficient trunk and posture control due to lack of innervation and/or muscle atrophy, leading to what?

Answer 21

poor posture (kyphosis)
reduced stability
lower respiratory efficiency

bracing alone is not effective, but continuous FES of trunk muscles and hip extensors corrects kyphotic seated posture (sitting with hunch back), spinal alignment, ventilations, expands ability to use both hands (bimanual), etc

Question 22

Respiratory muscle weakness after SCI has significant consequences. Such as?

Answer 22

high cervical injury affects diaphragm, innervated by C3-C5
may require mechanical ventilation

cervical to lower thoracic/upper lumbar injuries cause weak expiratory muscles, leading to poor cough and increased infection risk

Question 23

How is stimulation of the diaphragm (diaphragmatic pacing) achieved? (allows a person to breathe without a ventilator)

Answer 23

2 approaches

phrenic nerve stimulation (Avery system)
electrodes with cervical/thoracic surgically implanted on phrenic nerve (C3-C5)
stimulates the nerve, activates the diaphragm indirectly
can involve open or laparoscopic procedures
higher risk due to direct nerve involvement

diaphragmatic (direct muscle) stimulation
electrodes implanted directly into diaphragm muscle
stimulates motor points of the diaphragm (req mapping these motor points during surgery)
done via laparoscopic surgery (less invasive)
avoids direct nerve injury
requires mapping of motor points during surgery

Question 24

Phrenic vs Diaphragmatic (direct muscle) stimulation: invasiveness

Answer 24

dia: less invasive (laparoscopic only)

phrenic: more invasive

Question 25

Phrenic vs Diaphragmatic (direct muscle) stimulation: stim implantation approach

Answer 25

dia: laparoscopic phrenic: cervical/thoracic (open surgery or laparoscopic)

Question 26

Phrenic vs Diaphragmatic (direct muscle) direct nerve injury risk:

Answer 26

dia: none phrenic: possible

Question 27

Phrenic vs Diaphragmatic (direct muscle) recovery time:

Answer 27

dia: shorter phrenic: longer

Question 28

Benefits of diaphragmatic pacing?

Answer 28

can wean high cervical level SCI patients off mechanical ventilation reduces pulmonary infections enables speech and singing improves mobility (no ventilator dependency) enhances overall quality of life

Question 29

What is problem and solution of causing and involved with cough restoration? Benefits?

Answer 29

problem: after SCI, weak expiratory muscles, ineffective cough, mucus buildup, infections solution: spinal cord stimulation using implanted electrodes, typically placed between T9-T11 benefits: stronger cough, easier secretion clearance, fewer respiratory infections, reduced caregiver dependence, improved quality of life

Question 30

Loss of bladder control causes what? Medical management aims to decrease what, but is unable to provide control of bladder function Implanted neuroprostheses have been developed to provide stim to what to control bladder contraction

Answer 30

After SCI, loss of voluntary bladder control, leading to incontinence (which has significant morbidity), infections, potentially fatal renal failure aims to decrease detrusor hyperactivity and detrusor sphincter dyssynergia BUT is unable to provide control of bladder function implanted neuroprostheses developed to stim sacral nerve roots to control bladder contraction

Question 31

What is SARSI?

Answer 31

sacral anterior root stimulator implant, implanted in >2500 people Finetech Brindley Bladder System components: external controller, transmitter, implanted receiver, electrodes Limitation: requires dorsal rhizotomy (cutting sensory nerve), reduces reflex incontinence, BUT irreversible, limits widespread use

Question 32

What are issues with gait restoration through surface and implanted systems? What is the solution to this? Benefits?

Answer 32

surface electrodes can't reach deep muscles implanted systems require many channels Solution: intraspinal microstimulation (ISMS) implanting ultrafine microwires into anterior horn of spinal cord (lumbar region) one electrode is able to activate groups of muscles (synergies) Benefits requires less stimulation energy more natural movement patterns proven in animal models (cats) ongoing human trials

Question 33

Describe transcutaneous stimulation for motor and autonomic functional restoration benefits and limitatios

Answer 33

non invasive stimulation through the skin, targeting spinal circuits advantages: no surgery, safer alternative to epidural stimulation limitations: still early research stage no standardized clinical protocols yet

Question 34

Describe the problem causing, emerging solution, and proposed mechanisms for autonomic cardiovascular restoration

Answer 34

problem: SCI can cause orthostatic hypotension (drop in blood pressure when standing), hard to treat with meds emerging solution: transcutaneous spinal stimulation proposed mechanism: activates dorsal afferents, stimulating spinal inter/intrasegmental neurons, leading to sympathetic preganglionic neuron excitation, improving blood pressure regulation *still early stage research but high potential impact

Question 35

Describe the problems causing pressure injury risk factors solutions

Answer 35

very common after SCI pressure injuries: pressure ulcers, pressure sores, bed sores, decubitus ulcers risk factors: immobility, muscle atrophy, urinary incontinence treatment expensive, so prevention is key neuroprosthetic solutions surface stim, like Smart e-pants, intermittent electrical stim of gluteus maximus this redistributes pressure, improves blood flow (oxygenation), reduces tissue damage implanted stim targets inferior gluteal nerve increases muscle thickness improves pressure distribution

Question 36

epidural vs intraspinal implanted FES

Answer 36

epidural: on top of mural lining. less invasive, lower risk of direct spinal cord tissue injury, less precise targeting intraspinal: in spinal cord gray matter. more precise, can target different muscles, lower stim thresholds needed, invasive, complex

Question 37

Eight channel recipient regain what function

Answer 37

sit to stand, maintain upright posture, support stepping

Question 38

laparoscopic surgery: read

Answer 38

Laparoscopic surgery (often called keyhole surgery) is a minimally invasive surgical technique in which a surgeon operates through several very small incisions instead of one large cut. How it works A tiny camera called a laparoscope is inserted through one small incision. The camera sends images to a monitor so the surgeon can see inside the body. Thin surgical instruments are inserted through other small incisions to perform the operation phrenic nerve stim CAN use laparoscopy or open surgery diaphragmatic stim uses laparoscopic stim only