Peripheral Nerve Interfaces

Question 1

What is the Central nervous system and the peripheral nervous system?

Answer 1

CNS = brain and SC
PNS = from SC to periphery

Question 2

Site thé 4 subtypes of sacral segment and their amount

Answer 2

Cervical : 8
Thoracial : 12
Lombarial : 5
Sacral : 5

Question 3

Cite the different part of the peripheral nerve system (cf «peripheral nerve system»)

Answer 3

Spinal nerve, epineurium, fascicle, perineurium, axon, blood vessels, endoneurium

Question 4

What are the applications of peripheral nerve interfaces ?

Answer 4

For electrical stimulations (control of body functions, eg blood pressure, bladder, sexual function, digestion, breathing, etc.

For Neural recording (artificial limb control, decoding of physiological parameters such as heart rate)

Question 5

Site thé three subgroups of PNI

Answer 5

Non invasive , semi invasive and invasive interfaces.

Question 6

What’s the definition of an invasive recording method when it is about PNI ?

Answer 6

Introduction of instruments or other objects into the body or body cavities.

Question 7

Describe the principle of Cuff electrodes and their composition at the material level.

Answer 7

Non invasive method, the device is implanted AROUND the electrode. Long term interface.
In silicone rubber sheets and small platinum foils (limited number of electrode sites and minimum diameter)
Polyimide based cuffs (thin and active sites with small diameter)

Question 8

What are hybrid cuff electrodes ?

Answer 8

Polyimide technology with silicone rubber sheets with integrated electronic circuitry.

Question 9

What are the pros and cons of cuff electrodes ?

Answer 9

• do not harm the nerve

- low spatial selectivity

Question 10

What is the principle of the Flat Interface nerve electrode (FINE)

Answer 10

It varies nerve geometry (penetration of epineurium without damage of perineurium) so fascicles are distributed next to eachother (more selective stimulation)

Question 11

What are the pros and cons of FINE

Answer 11

Higher spatial selectivity but potential damage to the nerve due to reshaping.

Question 12

What is the principle of general invasive methods from PNI ?

Answer 12

Implantation inside the nerve (of epineurium and eventually perineurium) to record single AP.

Question 13

What are the pros and cons of invasive methods for PNI ?

Answer 13

High spatial selectivity but potential damage to nerve.

Question 14

What is the principle of the TIME (transverse intrafascicular multichannel electrode)?

Answer 14

For clinical studies
Stim and recording of ulnar and median nerve
Treatment of phantom limb pain
Possibly of connecting a motorized and sensor equipped prothesis (feeling prosthesis)

Question 15

How are TIME built ?

Answer 15

Sandwich method : platinum sheet imbedded between polyimide sheets. Two platinum non protected to record .

Question 16

How are time implanted ?

Answer 16

The nerve is dissected to insert time through it. Fixation is made at tabs with suture. Cables are lead transcutaneoulsy to a stimulator.

Question 17

What is the principle of sieve electrode ?

Answer 17

The nerve is cut and a stumps are placed in a tube with a sieve (=tamis) in the middle. The holes of the sieve have electrodes. When the nerve endings grow together again they grow through the holes.

Question 18

Site pros and cons of sieve electrodes

Answer 18

High selectivity but damaging.

Question 19

What is the principle of needle like electrodes ?

Answer 19

Invasive nerve interface
Small tungsten wire electrodes for diagnosis of nerve diseases (for acute investigation)
Utah array made out of silicon

Question 20

Site pros and cons of needle like electrodes

Answer 20

Optimal selectivity in recording and stimulation but potential damage of nerve

Question 21

What is the principle of Targeted muscle reinnervation (TMR)

Answer 21

Dissection and re outing of upper arm nerves to remaining muscles
It is not a true PNI
Manipulation of peripheral nerves in order to control neuroprosthetic devices

The motivation : it is a way to increase the signals strength from nerves in upper arm amputee patients for prosthetic control.

Question 22

Sites the problems and challenges surrounding TMR :

Answer 22

Risk of paralysis of the targeted muscle 
Phantom limb pain 
No long term studies
Size 
Weight 
Power supply