Hospital Central de Asturias Centro Universitario Unidad Multidisciplinar de los Trastornos del Movimiento Scalp evoked potentials induced by Therapeutic.

Hospital Central de AsturiasCentro UniversitarioUnidad Multidisciplinar de los Trastornos del Movimiento

Scalp evoked potentials induced by Therapeutic DBS of Subthalamic nucleus F. Fernández-González, F. Seijo, C. Vallés, B. Lozano, L. Guisasola, C. Salvador, A. Galindo

-Fz+Cz

-Cz-+Pz

-Pz+Oz

-Fpz+Fz

50 ms

Scalp evoked potentials

Therapeutic DBS-STN stimulation

R L

Hospital Central de AsturiasCentro Universitario

DBS - STN 1998 1999 2000 2001 2002 Total implants

Bilateral 3 4 12 25 11 90

Unilateral 6 0 6 5 2 19

Total patients 9 4 18 30 13+TOTAL 9 13 31 61 74+ 109

Movement Disorders Multidisciplinary Team

Pre - STN DBSOFF medication

Good Indication

Post - STN DBSON DBS - OFF Medication

Bad results?

6 months

N= 32 mA S Hz polemean 2.9 75.0 156.5 1.9 s.d. 0.6 20.4 25.6 0.7 min. 1.0 60.0 130.0 0.0 1th quar. 2.5 60.0 135.0 2.0 median 2.9 60.0 135.0 2.0 3th quar. 3.2 90.0 185.0 2.0 max. 4.0 120.0 185.0 3.0

0.3 a 0.4 mm

0.1 a 0.2 mm

1.0 mm

METHODOLOGYMETHODOLOGY

Monopolar G2 recording

G1

G2

Unitary RecordingUnitary Recording

Trigger threshold

From STN we can record neurons with single and bursting pattern,

From rostro-dorso-lateral Subthalamus we can record kinestethic unitary activities (32%).

The kinesthetic neurons are somatotopically organized.

Bipolar G1-G2 recording

G1

G2

Multiunitary RecordingMultiunitary Recording

1 Second

- 2 mm from AC-PC plane

- 3 mm from AC-PC plane

- 4 mm from AC-PC plane

- 5 mm from AC-PC plane

From rostro-dorso-lateral STN we can record a kinesthetic related multiunitary activity with a 4Hz pattern ( - 3 mm AC-PC plane) , descending 1 mm into the STN, the multiunitary

recording show different values ( an irregular pattern at 7-9 Hz)

Bipolar G1-G2 recording

G1

G2

Multiunitary RecordingMultiunitary Recording

1 Second

- 2 mm from AC-PC plane

- 3 mm from AC-PC plane

- 4 mm from AC-PC plane

- 5 mm from AC-PC plane

From Cortex (Cx) to Substantia Nigra pars reticulata

(SNr) two seconds of multiunitary neuronal activity

(bipolar recording) are recorded and stored in steps of

1 mm of the recording track, starting at cortex.

From the 2 sec. recording of multiunitary neuronal

activity the on line process calculates the integral of

the multiunitary one, and is plotted against the

distance to the target in a graphic that shows the

stereotactic angle of the electrode trajectory in the

sagital plane.

Right Hemisphere

Left Hemisphere

Cx STR CI STN SNr

Therapeutic tetraelectrodeTherapeutic tetraelectrode

7.5 mm

Intracerebral Extracraneal To the Electromyograph

G1

G2

Video 1 Video 2Video 3

Tetraelectrode StimulationTetraelectrode Stimulation

DisKinesias RigidityTremor

0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 27.5 30.0 32.5 35.0

10

.0 7

.5 5

.0 2

.5 0

.0 -2

.5 -5

.0 -7

.5 -1

0.0

-12

.5 -1

5.0

-17

.5 -2

0.0

10

.0 7

.5 5

.0 2

.5 0

.0 -2

.5 -5

.0 -7

.5 -1

0.0

-12

.5 -1

5.0

-17

.5 -2

0.00 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 27.5 30.0 32.5 35.0

Fp. 3(-3 IPC)

AC-PC Plane

Simulation of the electrical current diffusion by DBS monopolar stimulus.

Stimulus: 2mA, 100 secCurrent density = 0.02 mA/mm 2

2.5 mm

5.0 mm Stimulus: 5mA, 100 secCurrent density = 0.01 mA/mm 2

Is necesary a CD = 0.04 mA/mm2 to excite large axonsand a CD = 0.3 mA/mm2 to excite small ones.

0 1 2 3

Threshold to evoke motor responses(Sporadic motor responses)

polemean mA 3.0 3.5 4.3 5.3s.d. 1.2 1.2 1.6 1.8Motor evoked potential(Direct motor responses)

polemean mA 4.9 5.6 6.6 7.6s.d. 1.8 1.6 1.7 1.8

3210

3210

( x mA; 100 mS; 3 p.p.s)

Stimulation: DBS monopolar - 2 poleRecording: Ext. Dig. Communi’s rectified EMG

-40 -20 0.0 +20 +40 +60 +80 +100 +120 +140ms

60V

58.8ms 12.6ms

1.7mA

1.9mA

2.1mA

2.3mA

2.5mA Subthreshol

2.9mA

3.4mA

3.8mA Motor threshold

4.1mA

4.3mA

4.4mA

4.5mA

4.6mA Motor response

4.7mA

4.9mA

5.0mA

Data from 64 implants

N = 18Set A : < 2.5 mA

N = 14Set B : > 2.5 mA

Stimulus intensity needed to induce Motor threshold on Ext.Dig.Comm.

Linear correlation (Motor threshold)

- 0.9 0.7 0.50.9 - 0.7 0.60.7 0.7 - 0.90.5 0.6 0.9 -

<0.001 <0.001 <0.001 <0.001

Therapeutic DBS parameters

mA mS Hz Pole <0.05 <0.001 <0.01 >0.05

p

p

Mean differencesSet A versus Set B

Stimulus intensity needed to induce Motor threshold

2.0 2.5 3.4 4.3 0.5 0.7 1.0 1.7

Therapeutic DBS parameters

mA mS Hz Pole 2.7 58.8 143.3 1.9 0.6 14.3 20.3 0.6

MeanS.D.

MeanS.D.

Set A ( N = 18)

Stimulus intensity needed to induce Motor threshold

3.7 4.1 4.9 5.9 1.1 0.9 1.6 1.5

Therapeutic DBS parameters

mA mS Hz Pole 3.1 82.1 166.1 1.7 0.4 30.4 26.4 0.7

MeanS.D.

MeanS.D.

Set B ( N = 14)

5.0

TOTAL PatientsNumber = 32Median values = 3.8 3.0 2.5 mA

x mA100 S3 pps TOTAL

Number = 32

S.I. 10-20FpzFz

Cz

Pz

Oz

P4

C4

F4Fp2

-Fz+Cz

-Cz-+Pz

-Fpz+Fz

-Pz+Oz

100 ms -Fz+Cz

-Cz-+Pz

-Pz+Oz

-Fpz+Fz

50 ms

-Fpz+Fz

25 ms

40uV

5.5 ms 7 a 12 ms 75 ms

0 1 2 3

STN monopolar stimulation

Are this cortical recorded components EMG artefacts?

Stimulation: DBS monopolar - 2 poleRecording: Ext. Dig. Communi’s rectified EMG

-40 -20 0.0 +20 +40 +60 +80 +100 +120 +140ms

60V

58.8ms 12.6ms

1.7mA

1.9mA

2.1mA

2.3mA

2.5mA Subthreshol

2.9mA

3.4mA

3.8mA Motor threshold

4.1mA

4.3mA

4.4mA

4.5mA

4.6mA Motor response

4.7mA

4.9mA

5.0mA

5.3 mSecMasseter

8.4 mSecBorla mentonniana

13.2 mSecExt. Dig. Comm.

0 1 2 3

-Fpz+Fz

25 ms

40 V

5.5ms 7 a 12 ms 75ms

Stim.

0 1 2 3

S.I. 10-20FpzFz

Cz

Pz

Oz

P4

C4

F4Fp2

Mínimal1.1 mA

STIMULATION: Monopolar DBS-STN Tetraelectrode: 2Subminimal0.6 mARECORDING:A) Ext.Dig.Comm. Integrated EMG

B) Scalp evoked potentials

Subthreshold2.3 mA

Motor threshold4.6 mA

Direct motor responsesSporadic motor responsesNO motor responsesNO motor responses

N= 32 mA S Hz pole

mean 2.9 75.0 156.5 1.9 s.d. 0.6 20.4 25.6 0.7

Remember: therapeutic values

40uV

20 ms

Fpz - Fz

Fz - Cz

Cz - Pz

Pz - Oz

NO scalp responses Scalp evoked responses Scalp evoked responses

Fpz - Fz

Fz - Cz

Cz - Pz

Pz - Oz

Fpz - Fz

Fz - Cz

Cz - Pz

Pz - Oz

S.I. 10-20FpzFz

Cz

Pz

Oz

P4

C4

F4Fp2

+4

+0

-2-4

-6

+620 ms

+2

Stimulation:Bipolar 500 A; 100 s

0.3 a 0.4 mm

0.1 a 0.2 mm

1.0 mm

Trajectory

Target

Based in Parent (1998)

2 a 3 2 a 3

2 a 3

2 a 3

Ramón y Cajal (1906)

Capsula interna (2 a 3 )

Lenticular fasciculus or Forel’s field H2) (2 a 3 )

Subthalamic fasciculus (2 a 3 )

Ansa lenticilaris, Thalamic fasciculus or Forel’ H1. (2 a 3 )

Zona Incerta

Subthalamic nucleus

Cerebral peduncule

Hospital Central de AsturiasCentro UniversitarioUnidad Multidisciplinar de los Trastornos del Movimiento

S.I. 10-20FpzFz

Cz

Pz

Oz

P4

C4

F4Fp2

Ejemplo mapping: N. Mediano dcho.

Mapping de la activación cortical inducida por el estimulo umbral motor (3.5 mA) del núcleo Subtalámico derecho,aplicado como estimulaciónbipolar con cátodo en el polo 2 del tetraelectrodo implantado

Umbral motor

20ms

40uV

S.I. 10-20FpzFz

Cz

Pz

Oz

P4

C4

F4Fp2

Ejemplo mapping por estimulacióna nivel del núcleo Subtalámico Izdo, por estimulo bipolar con cátodo en el polo 2 del tetraelectrodo implantado

0 a 40 ms 252 a 292 ms 336 a 502 ms

Ejemplo mapping: Estimulo N. Mediano derecho

Ejemplo mapping: Estimulo n. Subtalámico izquierdo