24/09/2012
1
The lumping and splitting of spasticity
Prof Anand D Pandyan
Conceptual Model of
motor control
Mo
tor c
on
tro
l /
ca
pa
city
…
Me
Ma
rk
Se
nse
i
0 Twilight zone Life span (years)
Independence threshold
An illustration of motor control Control significantly improves with practice over time
Stroke is one of many adverse
events in life…
Mo
tor c
on
tro
l /
ca
pa
city
…
0 Twilight zone Life span (years)
Independence threshold
Stroke Increased activity
•Increased reflexes
•Spasticity
•Altered tone
•Spasm & Clonus
•Abnormal
movement patterns &
co-contraction
The paradoxical symptoms resulting from loss of activation
Reduced activity
•Weakness
•Fatigueability
•Loss of fine
motor control
24/09/2012
2
Why should one consider spasticity
as important?
Mo
tor c
on
tro
l /
ca
pa
city
…
0 Twilight zone Life span (years)
Independence threshold
Stroke
The Lance definition…. A motor disorder characterised by a velocity
dependent increase in the tonic stretch reflex
(muscle tone) with exaggerated tendon
reflexes, resulting from the hyper-excitability of
the stretch reflex …
The starting point for measuring spasticity
1. Resistance one feels when
stretching the joint
2. The state of readiness of the muscle
to act
What is muscle tone?
Need a measure of stiffness
Need a measure of muscle
activity
The Lance definition…. A motor disorder characterised by a velocity
dependent increase in the tonic stretch reflex
(muscle tone) with exaggerated tendon
reflexes, resulting from the hyper-excitability of
the stretch reflex...
Measuring spasticity
Measuring stiffness & muscle activity
Joint Angle
Fo
rce
to
mo
ve
lim
b
EMG
EMG
Displacement
Force/Moment
Muscle activity flexors
Muscle activity extensors
24/09/2012
3
Relationship between muscle activity and stiffness
0 20 40 60 80 100 120
10
10
20
RTPM pre treatment
RTPM post treatment
Angle (Degrees)
Fo
rce (
N)
0 20 40 60 80 100 120
20
40
60
Fast Flexor EMG pre treatment
Slow Flexor EMG pre treatment
Angle (Degrees)
EM
G (
uV
)
0 20 40 60 80 100 120
10
10
20
RTPM pre treatment
RTPM post treatment
Angle (Degrees)
Fo
rce (
N)
0 20 40 60 80 100 120
20
40
60
Fast Flexor EMG pre treatment
Slow Flexor EMG pre treatment
Angle (Degrees)
EM
G (
uV
)Slow
moveme
nt EMG
Slow
movemen
t Force
Brisk
movement
Force
Brisk
movement
EMG
Does stiffness change if muscle activity is eliminated?
20 38 56 74 92 110 128 146 164 182 200
50
20
10
40
70
100
Pre
Lin. Reg PrePost
Linear Reg Post
Angle (Degrees)
Fo
rce (
N)
RTPM pre - 1.063
RTPM post – 1.001
20 38 56 74 92 110 128 146 164 182 200
50
20
10
40
70
100
Pre
Lin. Reg PrePost
Linear Reg Post
Angle (Degrees)
Fo
rce (
N)
RTPM Pre - 0.432 (0.674)
RTPM Post - 0.155 (0.881)
Confounders (in brief) In the context of spasticity I
decided to leave the
measurement of stiffness aside and focus on the
measurement of muscle activity
So what did muscle activity look like
No Spasticity (~10%)
24/09/2012
4
Lance was correct velocity dependence existed ~ 20%
There also position dependent activity ~ 30%
The combination of course ~ 40% Two anomalies~1%
So what did muscle activity look like – very variable
Total Number of articles
Medline-314,Science direct-64 ,Web of science-309
Relevant articles – 265
Literature Review – 47 Controlled trial – 204
Total Number of articles read – 787
SCS - 14
24/09/2012
5
1. Spastic paralysis (this is a term I have seen in the literature since 1890’s)
2. The term is then used in the context of the positive symptoms in the classification developed by Hughlings Jackson
3. First form of a clinical definition produced by Denny-Brown 1960’s
4. The Lance definition of the 1980’s
Spasticity
Pa
tie
nt
clin
icia
n
The
rap
ist
Nu
rse
Ca
rer
Re
sea
rch
er
Lance Muscle
Tone
None Other
31% 35% 31% 3%
The assessment framework was no better
• Clinically the primary measure is the AS (& MAS) van Wijck et al 2001.
• The Tardieu Method is growing in popularity Haugh et al
2006.
There was a definition … but this was not an agreed
definition per se and it did not inform measurement or
clinical practice
Increased activity
•Increased reflexes
•Spasticity
•Altered tone
•Spasm & Clonus
•Abnormal
movement patterns
& co-contraction
Spasticity
•Increased reflexes
•Altered tone
•Spasm & Clonus
•Abnormal
movement
patterns & co-
contraction
EMG electrodes
Goniometer
Mechanism
Studying increased reflexes
sinmglKBI
L1 L2
k k
D D
m*g*l*sin(
l
2
21 LLdk
sinmglKBI
L1 L2
k k
D D
m*g*l*sin(
l
sinmglKBI
L1 L2
k k
D D
m*g*l*sin(
l
L1 L2
k k
D D
m*g*l*sin(
l
L1 L2
k k
D D
m*g*l*sin(
l
2
21 LLdk
24/09/2012
6
0 100 200 300 400 500 600 7003
2
1
0
1
2
3
Raw EMG
Rectified EMG
Smooth EMG
Raw EMG Amplitude
Time (ms)
Vo
lts (
V)
mk0
m
Quantifying reflex excitability
0 100 200 300 400 500 600 70020
15
10
5
0
5
Angle
Smooth EMG
Stretch Reflex Delay (Smooth)
Time (ms)
Deg
rees, V
mk1
mmk
3 m
Duration
Amplitude Latency
Outcome
measure
Main finding
Amplitude Greater in non-impaired subject p<0.05
Latency Latency shorter in stroke p<0.05
Rise time No difference
Duration No difference
Disordered sensori-motor control, resulting from an upper motor
neurone lesion, presenting as
intermittent or sustained involuntary activation of muscles
The lumping
• Spastic hypertonia: Velocity dependent increase in hypertonia with a catch when a threshold is exceeded. (no abnormal resting position)
• Dystonic hypertonia: After testing the limb will return to fixed resting posture that can vary with state of mind or attempted movement. (stiffness is independent of direction)
• Rigid hypertonia: Resistance to passive movement is not velocity dependent and no consistent abnormal posture is observed. (stiffness is independent of direction)
There was an attempt at splitting
(N.American Task Force) The start of the splitting - 1
Spasticity
•Increased reflexes (Not necessarily
abnormal)
•Altered tone
•Spasm
•Clonus
•Abnormal movement patterns & co-
contraction
24/09/2012
7
1. Resistance one feels when
stretching the joint
2. Readiness of the muscle to act
Altered tone
This is a confounded measure so
cannot contribute to a definition
This is reduced and is no different
to the definition of paralysis or
weakness – so there is a problem
The start of the splitting - 2 Spasticity
•Increased reflexes
•Altered tone
•Spasm
•Clonus
•Abnormal movement patterns & co-
contraction
The start of the splitting - 3 Spasticity
•Increased reflexes
•Altered tone
•Spasm •A transient but continuous muscular contraction
(cutaneous trigger)
•Clonus
•Abnormal movement patterns & co-
contraction
The start of the splitting - 4 Spasticity
•Increased reflexes
•Altered tone
•Spasm
•Clonus •A transient rhythmic / cyclical muscle contraction
– attenuated if a stimulus is removed
(proprioceptive and/or cutaneous)
•Abnormal movement patterns & co-contraction
The start of the splitting - 5 Spasticity
•Increased reflexes
•Altered tone
•Spasm
•Clonus
•Abnormal movement patterns & co-
contraction There is a need to resolve the
pathology and physiology
conundrum
The patterns of muscle activity – how do we define this?
An increase in the gain
and/or reduction in
threshold of a phasic
stretch reflex
demonstrated in a
relaxed muscle !
24/09/2012
8
Environment
Task
Individual
SP MC
SE
Spasticity as disorder control
Evidence for an epiphenomenon
Muscle
activity at
a slow
stretch
NF 1.1
(0.2)
0.97
(0.3)
0.73
(0.2)
0.74
(0.2)
0.7
(0.1)
F 1.1
(0.4)
1.1
(0.5)
1.4
(0.6)
0.82
(0.2)
1.7
(0.6)
Muscle
activity at
a fast
stretch
NF 1.2
(0.3)
1.1
(0.3)
0.9
(0.2)
0.7
(0.1)
0.8
(0.1)
F 1.0
(0.4)
1.3
(0.6)
1.3
(0.7)
1.1
(0.3)
1.9
(0.7)
W6 W0 W12 W24 W32
Time (an arbitrary non-linear scale)
Cap
acit
y (s
om
e ar
bit
rary
un
its)
Time course and muscle changes
My funders
– Action Medical Research, UK.
– N.Staffs Medical Institute, UK.
– EU
– DoH
– Biometrics Ltd, UK
– Allergan, UK