Targeted Nerve Transfers -------

Targeted Muscle Re-innervation

Douglas G. Smith, MD

Harborview Medical Center

and the University of Washington

What are we here to talk about ?

A nerve that currently dead ends (connects to the brain, but has no distal connection)

Transferred to the motor point of a muscle (a muscle that had its motor nerve removed)

Hopefully the nerve grows into the muscle (and finds new connection points and re-innervates)

Creates a Re-Wired Situation (Muscle now connect to a different part of the brain)

What are we here to talk about ?

Why ?

Body Powered Prostheses

• Refined in WWII• Moving shoulders forward

pulls on a bicycle cable• Bicycle cable operates hook

or hand and elbow.

Myoelectric Prostheses

• When muscles contract, they generate electric signals call ‘myoelectric signals’

• Electrodes (or antenna) on the skin over muscles can pick up these signals. The signals are then used to tell a motorized arm what to do.

Below-Elbow Amputee

• When the Brain says “close hand” the residual volar forearm muscle fires and creates ‘myoelectric signals’

• Electrodes on the skin pick up these muscle signals, close the prosthetic hand

• A ‘normal’ interaction between the Brain and the Functional Outcome of Open Hand and Close Hand!

Trans-Humeral Amputee

• Has Only 2 Normal Signals

• Residual Biceps for Elbow Up• Residual Triceps for Elbow Down

• When the Brain says ‘close hand’ or ‘open hand’ there are NO NORMAL ‘CLOSE OR OPEN THE HAND’ MUSLCES LEFT TO FIRE!

Trans-Humeral Amputee

• Currently, We TRICK the System

• By co-contracting, we have the arm ‘switch modes’

• Then, to close the hand, the person thinks ‘I have co-contracted to switch modes, now biceps will close the hand, and firing my triceps will open the hand.

• This is NOT a normal Brain - Functional result loop.

Transhumeral Targeted Muscle Reinnervation

• What if we could actually get 4 signals in the upper arm that worked normally with the proper brain thoughts.

• Bend elbow• Extend elbow• Close hand• Open hand

Seattle Times August 2007

Seattle Times August 2007

Seattle Times August 2007

4 Signal Prosthesis Control

Two Normal Anatomic Signals:• Elbow Up - Musculocutaneous N to lateral biceps

• Elbow Down - Proximal Radial N to triceps

Two Newly Re-Wired Signals:• Close hand - Median N to medial biceps

• Open hand - Distal Radial N to lateral triceps

Allows Simultaneous Control of Elbow and Hand with Normal Brain Thoughts !!

Targeted Nerve Reinnervation

also exists for the Shoulder

Disarticulation

Nerve-Transfer Surgery

Musculocutaneous n.

Median n.

Radial n.

P. Major muscle

Ulnar n.

P. Minor muscle

Not Me !

Who Actually Came up with This Wonderful

Idea ?

Who Started Doing the Surgeries: Gregory A. Dumanian, MD

The Division of Plastic SurgeryNorthwestern University - Chicago

Todd A. Kuiken, MD, PhD

Greg Dumanian

Neural Engineering Center for Artificial LimbsRehabilitation Institute of Chicago

Department of PM&R

• 54 yo lineman• May 2001 suffered

7,200 volt burns• Immediate bilateral

shoulder disarticulation

• Split-thickness skin grafts for closure of lateral chest wall wounds

Jesse Sullivan

How Did I Get Involved

I have known Todd Kuiken for 16 years

He started talking to me about this over 10 years ago

Every trip to Chicago, he would patiently explain and re-explain.

Finally I started to get it:THIS IS A BIG DEAL !

Note: This Surgery is not Experimental

Nerve Transfers done since 1901

Existing history of putting N into a protected environment either in bone or muscle

Difficulty with traditional ‘Dead End’ NerveNon-physiologic state

Neuroma formation

There is no implant or internal device - no FDA

How did I actually start doing the

surgery in Seattle

Seattle - September 7th, 2006

18 year old male, car accident and a traumatic right above-elbow amputation

The day of injury - I was away in Chicago, and my partner did the initial open amputation

I was asked me to do the definitive amputation

I had just been explaining to a Madigan Army trauma fellow what the Chicago group has been doing with nerve transfers

September 7th, 2006

In the OR - the nerves had been left long

I was explaining how the transfer would work - using the low bovie setting to test the distal muscle to find the point of maximal contraction, finding the distal motor point.

Army doc - says so…., and then I said so…

So …. we did our first transfers: Median N to distal biceps, and Radial N to brachialis

Patient got Hand Open and Hand Close Signals

Current Seattle Experience

Discuss with Patients and Families - when appropriate - talk about traditional nerve management- talk about evolving understanding of nerve transfers

Discussed with my dean- this is not experimental - standard pre-op discussion and consent

I have no formal research funding or protocol

Current Seattle Experience

Which patients do I consider it reasonable:

All new trans humeral patientsAll new shoulder disarticulation patientsAll major painful neuroma resection ptsEstablished TH or SD to obtain new signalsFor a unique group of lower limb amputees

Seattle Experience

32 Patients have had Nerve Transfer Surgery to Muscle Motor Points

16 Upper Limb Amputees15 Lower Limb Amputees

1 Non-Amputee

Seattle Experience: 16 Upper Limb

9 Patients: TMR done at time of initial definitive amputation

1 Elbow Disarticulation6 Trans Humeral Amputations2 Shoulder Disarticulation

5 Patients: TMR done as secondary procedure

2 Shoulder Disarticulation3 Trans Humeral Amputation

2 Patents: Trans Radial with neuroma pain - surgery done to resect neuroma and implant N into muscle motor point

Seattle Experience: 14 Cases of Nerve Transfer for New Myoelectric Signals

• 9/7/06 Traumatic AE

• 12/21/06Traumatic AE 1.5 years out

• 12/29/06Elbow Disarticulation for Infection

• 1/19/07 Traumatic Modified Shoulder Disarticulation

• 3/12/07 Traumatic AE

• 5/31/07 Traumatic Shoulder Disarticulation 1 year out

• 6/7/07 Traumatic AE

• 2/4/08 Traumatic SD

• 2/4/08 Definitive AE after necrotizing fasciitis open amp

• 4/17/08 Traumatic SD

• 7/24/08 Traumatic AE 1 yr out, Vancouver BC

• 7/31/08 Traumatic SD 1.5 yr out, severe pain

• 8/21/08 Traumatic SD

• 5/21/09 Traumatic AE, 3 ys out, 80 yo, primarily for pain relief

Seattle Experience: 14 Cases of Nerve Transfer for New Myoelectric Signals

6 Using a Electronic arm and taking advantage of the TMR function to varying degrees.

2 Have signals - no approval for any prosthetic arm

1 Has signals - using body power, no approval for myo arm

1 Has signals learned to use loaner myo arm but -- jail, EtOH, no follow up

1 Has signals, IVDA, jail -- never got an arm

1 Necrotizing fasciitis, sepsis, severe brain ischemia

1 Revision SD with some pain relief, getting signals but died 3 months post-op from aspiration and cardiac arrest

1 Four months out, has pain relief, no signals yet

What do I Think ?

How do I explain this evolving management of nerve to patients and families ?

Clinical Reality

I have been frustrated with traditional nerve management for quite some time.

I feel bad for many of our patients with nerve pain.

Thoughts

Traditional Nerve Management

Gently distract nerve, transect and allow it to retract to a more protected area.

However:This leaves very abnormal physiology

Dead end situationAxons sprouting to nowhereScar formationNeuromas

Has been standard of care for 100 years

Targeted Nerve Transfers

Transfer nerve to the motor point of a remaining muscle• Nerve grows into denervated muscle• Arborizes into the muscle (TMR)• Finds end organs• Reconnects to the brain• Remains physiologic

I think this works !Nerves remain physiologic

New signals do develop

Sensory and motor ingrowth

I believe there is less pain

Thoughts

BUT:It is Not Magic

Patients still have some pain

Some patients still have severe pain

Thoughts

If patient having revision for neuroma:

It makes sense

Think of nerve management options

Can we regain nerve physiology

If arborizes into muscle, no neuroma

Thoughts

If Done at Time of Definitive UL Amp:

Nerve transfer done distally

Signal location distal close to each other

Co-contraction a much bigger problem

Getting myo-prosthesis funded is not easy

Thoughts

It works

It is primarily about Nerves

Connects functional thoughts to new muscle signals

Potential to restore upper limb function and improve prosthetic use

My Conclusions

Todd Kuiken Robert LipschutzGreg Dumanian Kathy StubblefieldLaura Miller

Richard Weir

Neural Engineering Center for Artificial Limbs

Ping Zhou

Jon Sensinger

Jesse Sullivan

RICNWU

Thank You