review article shock waves in the treatment of...

Review ArticleShock Waves in the Treatment of MuscleHypertonia and Dystonia

Laura Mori,1 Lucio Marinelli,1 Elisa Pelosin,1 Antonio Currà,2

Luigi Molfetta,1 Giovanni Abbruzzese,1 and Carlo Trompetto1

1 Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genova,Largo Daneo 3, 16132 Genova, Italy

2 Department of Medical-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Polo Pontino,Via Firenze, 04019 Terracina, Italy

Correspondence should be addressed to Laura Mori; [email protected]

Received 25 April 2014; Revised 30 July 2014; Accepted 14 August 2014; Published 17 September 2014

Academic Editor: Ruiping Xia

Copyright © 2014 Laura Mori et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Since 1997, focused shock waves therapy (FSWT) has been reported to be useful in the treatment ofmuscle hypertonia and dystonia.More recently, also radial shock wave therapy (RSWT) has been successfully used to treat muscle hypertonia. The studies whereFSWT and RSWT have been used to treat muscle hypertonia and dystonia are reviewed in this paper.Themore consistent and longlasting results were obtained in the lower limbmuscles of patients affected by cerebral palsy with both FSWT and RSWT and in thedistal upper limb muscles of adult stroke patients using FSWT. The most probable mechanism of action is a direct effect of shockwaves on muscle fibrosis and other nonreflex components of muscle hypertonia. However, we believe that up to now the biologicaleffects of shock waves on muscle hypertonia and dystonia cannot be clearly separated from a placebo effect.

1. Introduction

Muscle hypertonia is a common finding in patients withupper motor neuron syndrome (UMNS) following stroke,multiple sclerosis, spinal cord injury, and traumatic braininjury. In these patients, the increase of muscle tone has beenrelated to the presence of spasticity, commonly defined as “amotor disorder characterised by velocity-dependent increasein the tonic stretch reflexes (“muscle tone”) with exaggeratedtendon jerks resulting from hyperexcitability of the stretchreflex” [1]. Spasticity in patients with UMNS is a major causeof disability affecting daily activities and quality of life [2].

However, in addition to spasticity, muscle contracture,in an early stage after brain or spinal cord insult, and jointretraction, in a later stage, make a significant contributionto muscle hypertonia [3]. Loss of sarcomeres with muscleshortening, degenerative changes at the myotendinous junc-tion, and accumulation of intramuscular connective and fattissues are the basic mechanisms of muscle contracture [4].Proliferation of fibrofatty connective tissue within the join

space and adhesions of sinovial folds are involved in jointretraction. Both muscle contracture and joint retraction aresecondary effects to muscle immobilisation in a shortenedposition [4]. Besides muscle contracture and joint retraction,another possible cause of muscle hypertonia is the impossi-bility of achieving a complete muscle relaxation. Such muscleoveractivity, not induced bymuscle stretch (spastic dystonia),has been frequently reported in patients with UMNS [4].Therefore, muscle hypertonia in patients with UMNS can bedivided into two components: hypertonia mediated by thestretch reflex (reflex muscle hypertonia), which correspondsto spasticity, and hypertonia due to muscle contracture,joint retraction, or nonreflexmuscle overactivity (intrinsic ornonreflexmuscle hypertonia).While it is difficult in a clinicalsetting to distinguish reflex and nonreflex contributions tomuscle hypertonia, biomechanical measures combined withEMG recordings can provide an objective separation of thesetwo components (for a review see Biering-Sørensen, 2006[5]).

Hindawi Publishing CorporationBioMed Research InternationalVolume 2014, Article ID 637450, 9 pageshttp://dx.doi.org/10.1155/2014/637450

2 BioMed Research International

Dystonia is a syndrome dominated by sustained mus-cle contractions, frequently causing twisting and repetitivemovements or abnormal postures [6]. Dystonia can beprimary (or idiopathic) and secondary (or symptomatic).Most lesions responsible for secondary dystonia involve thecaudate nucleus, the putamen, the globus pallidus, and thethalamus. As the lesions in these sites share the capability ofaltering the thalamic signalling to the frontal cortex, dystoniais thought to originate from a dysfunction of themotor cortexinduced by the derangement of thalamocortical connections[7–9].

Since the late 1980s, focused shockwaves therapy (FSWT)has beenwidely and successfully used in the treatment of painin various musculoskeletal disorders [10]. FSWT devices usepressure waves generated through electromagnetic, electro-hydraulic, and piezoelectric sources. These waves have theirpoint of higher pressure in the focus, which is placed withinthe treated tissue [11, 12]; for this reason they are defined asfocused shock waves.

In 1999, a new technology using a ballistic source togenerate pressure waves was introduced. This technologyis called radial shock wave therapy (RSWT). The ballisticsource consists of a tube within which compressed air (1–4 bar) is used to fire a bullet that strikes a metal applicatorplaced on the patient’s skin. The applicator transforms thekinetic energy of the bullet into radially expanding pressurewaves with a low penetration power (less than 3 cm). Theseunfocused shock waves have their point of highest pressureat the tip of the applicator, outside the treated tissue [11, 12].

It has been shown that both focused (FSWT) and unfo-cused (RSWT) shock waves produce cavitation bubbles inthe treated tissue [12]. The cavitation is consequent to thenegative phase of the wave propagation. The rapid collapseof the cavitation bubbles leads to secondary pressure waves.Cavitation-mediatedmechanisms could have a central role inthe action of both FSWT and RSWT for the musculoskeletalsystem [12].

From a theoretical point of view, shock waves could beuseful to treat dystonia and muscle hypertonia in patientswith UMNS. In accordance with the effects on tendondiseases [10], shock waves could have a direct effect onmuscle fibrosis and other nonreflex components of musclehypertonia, which are likely to be present also in somedystonic patients [8]. Furthermore, shock waves acting at themuscular level could modify the sensory inflow from thetreated muscle to the spinal cord, thus reducing spinal cordexcitability and mitigating spasticity.

The objective of the present review is to provide anoverview on the treatment of dystonia andmuscle hypertoniausing shock waves. For the preparation of this paper, aliterature survey in the PubMed electronic database wasperformed and covered the period from January 1985 to April2014. We selected all the studies in humans dealing withshock wave therapy and muscle hypertonia/dystonia withoutrestrictions. We found eight studies in which FSWT has beenused to treat muscle hypertonia [13–20] and one study usingFSWT to treat dystonia [21]. In three studies, RSWT has beenused to treat muscle hypertonia [22–24]. In one study, aimedat investigating the action mechanisms of shock waves in

patients with muscle hypertonia, FSWT has been deliveredto healthy subjects to evaluate the effect of shock waves onthe peripheral and central nerve conduction [25] (Table 1).

2. FSWT to Treat Hypertonia in Patients withCerebral Palsy (CP)

Lohse-Busch et al. were the first to use shock waves in anopen-label single-arm study to treat muscle hypertonia inchildren and young adults with CP (33 patients), tetraparesisafter trauma (1 patient), kernicterus with athetosis (1 patient),and arthrogryposis multiplex congenita (1 patient) [14].Shock waves were delivered to lower limb muscles affectedby contractures (hamstrings, triceps surae, and ileopsoas).To disperse the shock waves throughout the muscles, theirfocus (intensity = 0.06mJ/mm2) was placed either withinthe coupling cushion of the therapy source (Minilith SL1,Storz Medical AG) or obliquely outside the patient’s body.Shock waves were delivered in a single session and eachmuscle was treated with 500 shots. The patients received alsophysiotherapy. The outcome measure was the passive rangeof movement (ROM) of hip, knee, and ankle joints.Themainresult was that passive ROM increased after the treatment forseveral weeks (at least 3-4weeks). Positive clinical effects werealso found in muscle hypertonia, cocontractions, dyskinetic,and ataxic symptoms.

More recently, Amelio and Manganotti investigated, ina placebo-controlled study, the effect of a single session ofFSWT in 12 children with CP showing a unilateral spasticequinovarus foot [13].The shock waves (Modulith SLK, StorzMedical AG) were delivered to the hypertonic triceps surae(1500 shots to each of the 3 muscles, 4500 shots in total)using an intensity of 0.03mJ/mm2. Each patient was treatedwith placebo followed 6 weeks later by FSWT. The placebotreatment was applied with the identical instrumentationsused for FSWT and with the same sound, but withoutshock wave energy. The patients were evaluated immediatelybefore and after the treatment (both placebo and active).The patients were also evaluated 1, 4, and 12 weeks afterFSWT. No physiotherapy was performed after FSWT. Theoutcome measures were passive ROM of ankle joint, theModified Ashworth Scale (MAS) for ankle plantar flexors,and a baropodometric assessment. After FSWT, muscle tonewas reduced and passive ROMwas increased.The baropodo-metric evaluation revealed an increase in the whole plantarsurface area of the treated limb. These effects persisted 4weeks after FSWT, but they were not present 12 weeks after.No changes were observed after placebo treatment. No sideeffects were observed in any patient [13].

3. RSWT to Treat Hypertonia in Patients withCerebral Palsy (CP)

In 2011, Vidal et al. assessed the efficacy of 3 sessions of RSWT(1 session per week; intensity: 2 Bars; 2000 shots for eachmuscle) in 15 CP patients [24]. RSWTwas delivered bymeansof a Swiss Dolorclast (EMS-Switzerland) device. The studyfocused on 40 spastic muscles (forearm and wrist flexors;

BioMed Research International 3

Table1

Reference

Participants

Treatm

ent

Treatedmuscle

sOutcomem

easures

Placebo

Other

treatments

Results

Side

effects

Lohse-Bu

sch

etal.

1997

[14]

35child

renand

youn

gadults

with

CP

FSWT:

1sessio

n;0.06

mJ/m

m2 ;500

shotsfor

each

treated

muscle

Ham

strings,

Tricepssurae

and

Ileop

soas

ROM

No

Physiotherapy↑RO

Mlasting≥3weeks

No

Amelioand

Mangano

tti,

2010

[13]

12child

renwith

CP

FSWT:

1sessio

n;0.03

mJ/m

m2 ;4500

shotsintotal

Tricepssurae

ROM,M

AS,

baropo

dometry

1sessio

nof

placebo

follo

wed

6weeks

later

byFS

WT

No

↑RO

M,↓

MASscores,and

↑plantarsurface

area

lasting≥4weeks

and<12

weeks

after

FSWT.No

effectsaft

erplacebo

No

Vidaletal.

2011[24]

15child

renand

adultswith

CP

RSWT:

3sessions

(1/w

eek);2

Bars;in

each

session,

2000

shotsfor

each

treated

muscle

Forearm

andwris

tflexors;hip

addu

ctors;soleus

andhamstr

ings

ASforu

pper

limb

muscle

s;RO

Mfor

lower

limbmuscle

s

Placebowas

applied

to13

muscle

s(patients’nu

mber

notspecified)

Not

specified

↓ASscores

and↑RO

Mlasting≥8weeks

and<12

weeks

after

FSWT.No

effectsaft

erplacebo

Petechiaea

ndlight

pain

durin

gRS

WTin

3patie

nts

Gon

kova

etal.

2013

[22]

25child

renwith

CP

RSWT:

1sessio

n;1.5

Bars;4500shotsin

total

Tricepssurae

ROM,M

AS,and

baropo

dometry

1placebo

session,

then

RSWTaft

er1

mon

thNo

↓MASscores

and↑RO

Mlasting≥4weeks

after

RSWT.Noeffectsaft

erplacebo

No

Mangano

ttiandAmelio,

2005

[15]

20adultswith

posts

troke

spasticity

FSWT:

1sessio

n;0.03

mJ/m

m2 ;4700

shotsintotal

Wris

tflexors;

interosseus

muscle

softhe

hand

ROM,A

S,MCV

,andF-waves

from

ADM;E

MG(FDI)

1placebo

session

follo

wed

byFS

WT

after

1week

Not

specified

↑RO

Mlasting

4–12

weeks

after

FSWT.↓ASscores

lasting4–

12weeks

inwris

tflexorsandlasting≥12

weeks

infin

gersflexors

after

FSWT.Nochangeso

fMCV

,F-w

aves,and

EMG

after

FSWT.Noeffectsaft

erplacebo

No

Tron

catietal.

2013

[20]

12adultswith

posts

troke

spasticity

FSWT:

2sessions

(1sessionperw

eek);

0.08/0.10

5mJ/m

m2 ;

800/1600

shotsfor

each

treated

muscle

Flexor

muscle

sin

theforearm

;interosseus

muscle

softhe

hand

MAS,subscoreso

ftheu

pper

limbFM

scalefor

motric

ity,

ROM

andpain;

perceivedbenefit

(VAS)

No

Not

specified

↑RO

Mandmotric

itysubscoresa

nd↓MAS

scores

lasting≥6mon

ths.↓

Pain

lasting1–12

weeks.N

ochangesinperceived

benefit

(VAS)

No

Santam

atoet

al.

2013

[18]

16adultswith

posts

troke

spasticity

FSWT:

5sessions

(1sessioneveryday

startingfro

mBo

NT-Ainjection);

0.03

mJ/m

m2 ;2000

shotsintotal

Flexor

digitorum

superficialismuscle

MAS;VA

Sforp

ain

andfre

quency

ofmuscle

spasms

No

BoNT-A

↓MASscores

and↓pain

lasting1–3mon

ths.↓

Frequencyof

muscle

spasmslastin

g≥3mon

ths.

In16

patie

ntstreated

with

BoNT-Aandele

ctric

alstim

ulation,

ther

esults

weres

horter

indu

ratio

nandsm

allerinsiz

e

No


Table1:Con

tinued.

Reference

Participants

Treatm

ent

Treatedmuscle

sOutcomem

easures

Placebo

Other

treatments

Results

Side

effects

Moo

netal.

2013

[16]

30adultswith

posts

troke

spasticity

FSWT:

3sessions

(1sessionperw

eek);

0.089m

J/mm

2 ;1500

shotsintotal

Medialand

lateral

gastrocnem

ius

ROM,clonu

sscore,FM

assessmento

fthe

lower

limb,MAS,

biom

echanical

assessment(PE

TandTT

A)

1placebo

session

follo

wed

byFS

WT

Physiotherapy↓MASscores

andPE

Tvalues

lasting1–4weeks.

Noeffectsaft

erplacebo

No

Santam

atoet

al.

2014

[17]

23adultswith

posts

troke

spasticity

FSWT:

1sessio

n;0.10mJ/m

m2 ;4500

shotsintotal

Tricepssurae

ROM,M

AS,MCV

,andF-waves

from

AH

No

No

↓MASscores

and↑RO

Mlasting≥1m

onth

after

FSWTin

thep

atientsw

ithbaselin

eHS<4.No

long

-lasting

effectsin

patie

ntsw

ithHS=4.No

MCV

andF-waves

changes

after

FSWT

Pain

in5

subjectsand

localw

eakn

ess

in2subjects

Kim

etal.

2013

[23]

57adultswith

posts

troke

spasticity

RSWT:

5sessions

(1sessionevery2or

3days);1.6

Bars;in

each

session,

3000

shotsintotal

Subscapu

laris

muscle

ROM,M

AS,VA

Sforp

ain

No

Physiotherapy↓MASscores,↓

pain,and↑

ROM

lasting

4weeks

Petechiaein1

patie

ntandlight

pain

durin

gRS

WTin

some

patie

nts

Trom

petto

etal.

2009

[21]

3adultswith

second

ary

dysto

niaa

nd3

with

writer’s

cram

p

FSWT:

4sessions

(1sessionperw

eek);

0.03

mJ/m

m2 ;up

to8000

shots

Forearm

andhand

muscle

s

UDRS

,ADDS,

4-po

intp

ain

intensity

scale,

mediannerve

SEPs,F-w

aves

from

ADM

1placebo

session

follo

wed

byFS

WT

after

2weeks

No

Inpatie

ntsw

ithsecond

ary

dysto

nia,clinicalbenefito

ndysto

niaa

ndpain

lasting

1-2mon

ths.Lessconsistent

effectson

writer’scram

ppatie

nts.Nochangeso

fSE

PsandF-waves

after

FSWT.Noeffectsaft

erplacebo

No

Sohn

etal.

2011[19

]

10adultswith

posts

troke

spasticity

FSWT:

1sessio

n;0.10mJ/m

m2 ;1500

shotsintotal

Medial

gastrocnem

ius

muscle

MAS,F-waves

from

AHand

H-reflex

from

soleus

No

No

↓MASscores

justaft

erFS

WT(nofollo

w-up).N

ochangeso

fF-w

aves

and

H-reflex

Mild

pain

durin

gFS

WT

Mangano

tti,

etal.

2012

[25]

10healthy

subjects

FSWT:

1sessio

n;0.03

mJ/m

m2 ;1600

shotsintotal

RightA

DM

MCV

,F-w

aves,and

MEP

sfrom

right

ADM;SAPfro

m5∘

fingerb

yulnar

nerves

timulation

No

No

Nochangesinanyof

the

investigated

parameters

No

ADDS:arm

dysto

niadisabilityscale;ADM:abd

uctord

igiti

minim

i;AH:abd

uctorh

allucis;AS:Ashworth

scale;Bo

NT-A:b

otulinum

toxintype

A;C

P:cerebralpalsy

;EMG:electromyography

;FDI:firstdo

rsal

interosseus;FM

:Fug

l-Meyer;F

SWT:

focusedshockwaves

therapy;

HS:Heckm

attscale;M

AS:mod

ified

Ashworth

scale;MCV

:motor

cond

uctio

nvelocity;M

EPs:motor

evoked

potentials;

PET:

peak

eccentric

torque;R

OM:p

assiv

erange

ofmovem

ent;RS

WT:

radialshockwaves

therapy;SA

P:sensoryafferentp

otentia

l;SE

Ps:sensory

evoked

potentials;

TTA:torqu

ethresho

ldangle;UDRS

:unifieddysto

niaratin

gscale;

VAS:visualanalogue

scale.


hip adductors; soleus and hamstrings), which were dividedinto 3 groups. In group I (14 muscles), RSWT was deliveredonly to the spastic muscles; in group II (13 muscles), RSWTwas delivered to the spastic muscles and their antagonists;in group III (13 muscles), placebo stimulation was deliveredonly to the spastic muscles. The characteristics of placebostimulation were not specified. In the methods, it was onlyreported that patients received placebo “via application of asham RSWT with sound.” The outcome measure for upperlimb muscles was hypertonia measured with the Ashworthscale (AS), while for lower limbmuscles the outcomemeasurewas the passive ROM. Patients were evaluated just beforethe treatment and 1, 2, and 3 months after the last session.One month after RSWT, AS scores decreased in group Imuscles and passive ROM values increased in both group Iand group II muscles. No differences were found betweengroup I and group IImuscles and no changes were found afterplacebo stimulation (group III). The results were maintained2 months after the last session of RSWT, while 3 monthsafter they were no longer present. No major side effects werereported [24].

Gonkova et al. [22] used a single session of RSWTto treat the flexor muscles of the ankle in 25 childrenwith CP (intensity: 1.5 Bars; 1500 shots for each of the 3muscles forming the triceps surae). Forty ankle flexor musclegroups were treated using a BTL-5000 unit (BTL Columbia,South Carolina, USA). The outcome measures were musclehypertonia, measured with the MAS, passive ROM, and abaropodometric assessment. MAS scores and ROM valueswere collected before RSWT, immediately after RSWT, and2 weeks and 4 weeks after RSWT. The baropodometricassessment was performed before and immediately afterRSWT. Each subject was treated first with placebo stimula-tion and, amonth later, with the shock waves. For the placebotreatment, two cushions were inserted between the applicatorand the patient’s skin and 100 shots were applied with thelowest intensity. After RSWT, no other physiotherapy wasperformed in the following 4 weeks. The results showedthat the reduction of MAS scores and the increase of ROMvalues were present just after RSWT and lasted 4 weeks.The baropodometric assessment revealed an increased peakpressure under the heel and an increase of the foot contactarea after RSWT. No effects were found after the placebostimulation. The authors said that the RSWT was “well-tolerated”; no other comments on possible side effects werereported in the paper [22].

4. FSWT to Treat Hypertonia in Patients withStroke: Upper Limb Studies

In 2005, Manganotti and Amelio reported the effect of asingle session of FSWT in 20 adult patients with poststrokespasticity. This was a placebo-controlled study, in which eachpatient was first treated with placebo and then, after 1 week,the shock waves were applied. Shock waves were deliveredto flexor muscles in the forearm (flexor ulnaris and flexorradialis, total 1500 shots) and intrinsic muscles of the hand(interosseus muscles, total 3200 shots) using an energy of

0.03mJ/mm2 (Modulith SLK, Storz Medical AG). Differentpoints of application were used to treat several areas of thehypertonic muscles. Placebo treatment was applied with thesame instrumentations and the same sound, but withoutshock wave energy. The outcome measures were muscle toneof wrist and fingers flexors, evaluated using the AS andpassive ROM. Motor nerve conduction velocity and F-wavesfrom abductor digiti minimi (ADM) were also recorded.Patients were evaluated before placebo, immediately afterplacebo, before FSWT (1 week after placebo), and 1, 4, and12 weeks after FSWT. In addition, a needle electromyography(EMG) recording in the first interosseus muscle was per-formed 4 weeks after the treatment. Muscle tone was reducedin wrist flexors 1 week and 4 weeks after FSWT, while infingers flexorsmuscle tonewas reduced 1, 4, and 12weeks aftershock waves. Passive ROMwas increased 1 week and 4 weeksafter FSWT in both wrist and fingers flexors. Muscle toneand passive ROM did not change after placebo. No changeswere found in the electrophysiological parameters both afterFSWT and placebo. No adverse effects were observed in anypatient [15].

In 2013, Troncati et al., in an open study without a placeboarm, used two sessions of FSWT (1 week between the firstand the second session) to treat the hypertonic flexormusclesin the forearm (1600 shots for each treated muscle) andinterosseus muscles of the hand (800 shots for each muscle)of 12 adult stroke patients. Shock waves were applied to flexormuscles using an energy of 0.105mJ/mm2, while for intrinsichandmuscles an energy of 0.08mJ/mm2 was used (ModulithSLK, Storz Medical AG). Patients were examined at baseline,immediately after FSWT, and 1 week, 3months, and 6monthsafter FSWT. Muscle tone of upper limb muscles was assessedwith MAS; furthermore, the subscores of the upper limbsection of the Fugl-Meyer Scale (FM) for motricity, passiveROM, and pain were used. Immediately after the treatment,muscle tone was reduced (not only in the treated muscles,but also in the shoulder external rotators and in the flexorsof the elbow) and FM subscores improved. The effects onMAS, passive ROM, and motricity subscores persisted for 3and 6 months after FSWT. The possible adverse effects havenot been discussed in the paper [20].

The SBOTE (Spasticity treated by Botulinum Toxin andESWT) study was designed to compare, in 32 stroke patients,the effectiveness of the following 2 treatments for upper limbspasticity: Botulinum Toxin A (BoNT-A) + FSWT versusBoNT-A + Electrical Stimulation (ES) [18]. BoNT-A wasinjected in the flexor digitorum superficialis (FDS)muscle. In16 patients, immediately after BoNT-A injection, ES (5Hz ofrectangular biphasic balanced current at the intensity of 50–90mA) was applied on the FDS belly for 30 minutes twicea day for 5 days. In the other 16 patients, immediately afterBoNT-A injection, FSWTwas delivered once a day for 5 days.Shock waves were focused on the forearm (2000 shots on theFDS belly and its proximal muscle-tendon junction) using anenergy of 0.03mJ/mm2 (Modulith SLK, Storz Medical AG).The outcome measures were MAS and VAS for pain andfrequency of muscle spasms. Patients were evaluated beforeand after the treatment (15, 30, and 90 days after). In the


patients treated with FSWT, muscle tone reduction persisted30 days after the treatment and the reduction of the frequencyof muscle spasms persisted 90 days after the treatment. Thereduction of pain was significant 30 days after the treatment.The results obtained in the patients treated with ES weresignificantly shorter in duration and smaller in size. None ofthe patients reported adverse effects [18].

5. FSWT to Treat Hypertonia in Patients withStroke: Lower Limb Studies

The study of Sohn et al. [19] was designed to investigate themechanisms of FSWT on muscle hypertonia. The clinicaleffects induced by shock waves were evaluated only imme-diately after the treatment. This study will be described inSection 8.

In 2013, Moon et al. used FSWT to treat the hypertonicankle plantar flexor muscles in 30 stroke patients. Three ses-sions of FSWT, generated by a piezoelectric source (RichardWolf GmbH), were delivered to the medial and lateral gas-trocnemius (1500 shots) using an energy of 0.089mJ/mm2.A single session of placebo treatment, provided using thesame equipment used for FSWT avoiding contact betweenthe device and the subject’s skin, was performed 1 week beforeFSWT. Physiotherapy was performed during the study. Theclinical outcome measures include the MAS and the passiveROM. Furthermore, a biomechanical assessment of musclehypertonia was made using an isokinetic dynamometer. Thepeak value of the eccentric torque occurring during passivejoint movements (Peak Eccentric Torque, PET) and the jointangle at which the eccentric torque begins to occur (TorqueThreshold Angle, TTA) were measured. No changes werefound after placebo treatment.MAS scores and PET and TTAvalues decreased immediately after FSWT. MAS scores andPET values also decreased 1 week after FSWT, but such resultswere no longer present 4 weeks after FSWT [16].

Very recently, Santamato et al. applied a single session ofFSWT to treat the hypertonic ankle plantar flexor musclesin 23 adult stroke patients using an open uncontrolled studydesign [17]. Shock waves at the energy of 0.10mJ/mm2 wereapplied using EvoTron RFL0300 (Sanuwave AG). A numberof 1500 shots were used to treat each gastrocnemius muscleand soleus muscle. Each patient was evaluated at baseline,immediately after FSWT, and 30 days after FSWT. No phys-iotherapy was performed after FSWT. The clinical outcomemeasures were the MAS and the passive ROM. At baseline,the patients underwent a muscle ultrasound evaluation ofankle plantar flexors and muscle echogenicity was measuredusing the Heckmatt scale. Furthermore, at baseline and 30days after FSWT, distal motor nerve conduction velocityand F-waves responses from abductor hallucis elicited bytibial nerve stimulation were recorded. Immediately afterthe treatment, there was a decrease of MAS score and anincrease of passive ROM. These results persisted 30 daysafter only in those patients with baseline echogenicity levelof I, II, and III on the Heckmatt scale. After FSWT, theneurophysiological assessment did not show any significantchange in nerve conduction velocity and spinal excitability.

Mild adverse effects lasting only a few days were reported(pain in 5 subjects and local weakness in 2 subjects). Thisstudy suggests that FSWT does not produce long-lastingeffects when the muscle is atrophic and replaced by fat andfibrotic tissue [17].

6. RSWT to Treat Hypertonia in StrokePatients: A Study in the Upper Limb

In 2013, Kim et al. used 5 sessions of RSWT (1 session every2 or 3 days; intensity: 1.6 Bar; 3000 pulses per session) totreat the spastic subscapularis muscles in 57 stroke patients.The device used was Masterplus MP 200 (Storz MedicalAG, Tagerwillen, Switzerland). The outcome measures werepassive ROM and the MAS (shoulder external rotation).Furthermore, shoulder pain was evaluated in a subgroup of18 patients with a minimental status examination (MMSE)> 24 and a visual analogue scale (VAS) for shoulder pain >4/10. Patients were evaluated at the start of each session (5times) and once a week after the last session for a period ofsix weeks (6 times). During the period of the study, patientsreceived physiotherapy including massage, passive musclestretching, and active exercises. The study was not controlledversus placebo. During the 5 sessions of RSWT and in thesubsequent 4 weeks, MAS and VAS scores for shoulder painwere lower and passive ROM values were higher, comparedto baseline values. Four weeks after the last session the effectsdecreased. No serious side effects were observed over the 6weeks follow-up period [23].

7. FSWT to Treat Dystonia

Trompetto et al. used FSWT to treat dystonia in a smallgroup of subjects: 3 patients with secondary dystonia due to alesion in the basal ganglia and 3 patients with writer’s cramp[21]. Shock waves were delivered in 4 sessions (once weekly),using an average intensity of 0.03mJ/mm2 (Modulith SLK,Storz Medical AG). In patients with secondary dystonia, themuscles responsible for the dystonic movements were iden-tified and treated (800 shots for the selected intrinsic handmuscles and 2000 shots for the selected flexor and extensormuscles in the forearm). In the 3 subjects with writer’s cramp,FSWT was widely distributed to the volar (3000 shots) anddorsal (3000 shots) surfaces of the forearm. Each patientwas treated with a single session of placebo 2 weeks beforeFSWT. In the subjects with secondary dystonia, the outcomemeasures were the unified dystonia rating scale (UDRS) anda four-point pain intensity scale. In the subjects with writer’scramp, the arm dystonia disability scale (ADDS) was used. Inaddition, before the first and after the last session of FSWT,somatosensory evoked potentials obtained by median nervestimulation and motor nerve conduction velocity with F-waves from ADM muscle were recorded in each patient.While placebo treatment left unchanged the clinical scoresin all the subjects, after FSWT the 3 patients with secondarydystonia showed amarked improvement of both dystonia andpain lasting at least 1 month after the last session. In the 3patients with writer’s cramp, the improvement after FSWT


was less consistent being effective only in two subjects. Nosignificant changes of electrophysiological values were found.Shock waves induced side effects in none of the subjects,including weakness in the treated muscles [21].

8. Neurophysiological Studies

In 2011, Sohn et al. used a single session of FSWT (Evotron,SwiTech Medial AG), delivered to the medial gastrocne-mius muscle (1500 shots), in 10 adult poststroke hemiplegicpatients with hypertonia in ankle plantar flexor muscles(triceps surae) using an energy of 0.1mJ/mm2. The subjectswere investigated before and immediately after the treatment.The outcome clinical measures were the MAS score of ankleplantar flexors muscles. To study spinal excitability, F-wavesin the abductor hallucis muscle and H-reflexes in the soleusmuscle were recorded. After the treatment, the MAS scoreswere reduced. Mild pain was produced by the treatment.The absence of a significant effect on spinal excitability wasdiscussed since F-waveminimal latency,H-reflex latency, andH-reflex/M-wave ratio remained stable before and after thetreatment [19].

In a group of ten healthy subjects, Manganotti et al.[25] investigated the effects on peripheral nerve conductionand corticospinal excitability induced by a single session ofFSWT applied to the right ADMmuscle (1600 shots at energyof 0.03mJ/mm2, delivered by Modulith SLK-Storz MedicalAG). Motor nerve conduction velocity and F-waves wererecorded from right ADMmuscle by ulnar nerve stimulation,sensory action potentials were recorded from the right Vfinger by ulnar nerve stimulation, and motor potentials wereevoked by transcranial magnetic stimulation in the rightADMmuscle. The subjects were investigated before and afterFSWT (immediately, 15 and 30 minutes after FSWT). Nochanges were found in any of the investigated parameters[25].

9. Discussion

9.1. ShockWaves Effectiveness and Safety. The 4 studies in CPpatients (2 studies with FSWT and 2 studies with RSWT)provided rather consistent results. In all the studies, thetreatment was applied to the lower limbmuscles. Only in onestudy [24] the shockwaveswere also applied to the upper limbmuscles. Only one study was a multiple sessions study [24],while the otherswere single session studies. All the studies butone [14] were placebo controlled. In all the 4 studies musclehypertonia was evaluated clinically and muscle hypertoniawas reduced for at least 3-4 weeks after the treatment. In the2 studies where a complete time course of the shock waveseffects was assessed, 3 months after the treatment the benefitwas no longer statistically significant [13, 24]. Taken together,these studies demonstrate that the reduction of muscle toneafter shock waves in CP patients lasted more than 3-4 weeksand less than 3 months.

Similarly, the 3 studies in which FSWT was used totreat hypertonic upper limb muscles in adult stroke patientsgave consistent results. Only one of them [15] was placebo-controlled. Two were multiple sessions studies [18, 20], while

the remaining one was a single session study. In all the 3studies, the shock waves were focused on the flexor musclesin the forearm and in the intrinsic hand muscles. The effectswere long lasting since the reduction of muscle hypertonia ormuscle spasms, evaluated clinically, was still present 3months[15, 18] and even 6 months [20] after the treatment.

The results obtained in the 2 studies in which FSWT wasapplied to the lower limbmuscles of adult stroke patientswereless relevant. The multiple sessions, placebo-controlled studyof Moon et al. [16] was the only study treating hypertoniawith shock waves in which muscle tone was measured notonly through clinical, but also through a biomechanicalassessment. The reduction of muscle hypertonia lasted only1 week after the treatment; 4 weeks after FSWT the effect wasnot significant. In the other study, a single session of FSWTproduced a reduction of muscle hypertonia 4 weeks afterthe treatment only in those patients without severe musclesecondary changes [17].

In the study performed using RSWT in the adult strokepatients, the treatment was focused on the subscapularismuscle. This was a multiple sessions study without placebo.The clinical evaluation revealed an improvement of muscletone, which was fairly stable during the 4 weeks after the lastsession; however the effect decreased during the followingweeks.

A study performed in a small sample of subjects showedthat FSWT can be useful in patients with secondary dystonia,reporting a reduction of involuntarymuscle contractions andpain in all the tested subjects for at least 1 month. Inconsistentresults were obtained in patients with writer’s cramp [21].

No major adverse effects were observed in any study.Only mild and short-lasting adverse effects were reported,including pain, local weakness, small superficial hematomas,and petechiae [17, 24].

9.2. The Mechanisms of Action. Theoretically, shock wavescould reduce the excitability of the stretch reflex altering thenerve conduction of sensory and motor fibers connectingthe treated muscle to the spinal cord. Furthermore, themechanical stimulation by shock waves on the muscle fibersadjacent to the tendon could decrease spinal excitability [15,17]. However, the neurophysiological assessments performedbefore and after FSWT in patients with muscle hypertonia[15, 17, 19], in patients with dystonia [21], and in healthyvolunteers [25] did not find any changes inmotor and sensoryperipheral nerve conduction and in corticospinal excitability.The lack of changes in peripheral conduction and spinalexcitability suggests that the most probable mechanism ofaction is a direct effect of shock waves on muscle fibrosis andother nonreflex components of muscle hypertonia. Throughits action on nonreflex hypertonia, however, shock wavescould also reduce spasticity. The reduced extensibility due tosoft tissue changes causes any pulling force to be transmittedmore readily to themuscle spindles [26]. In this condition, anexaggerated spindle discharge in response to muscle stretchresults in an increased stretch reflex [4]. Thus, the reduc-tion of nonreflex hypertonia could modify muscle spindlesexcitability, leading to a secondary reduction of spasticity.


9.3. The Placebo Effect. The major limitation of the reviewedstudies is represented by placebo treatment. Six studies werenot placebo controlled [14, 17–20, 23]. In the remaining 6studies, the placebo treatments were applied using the sameinstrumentations used for FSWT or RSWT, but withoutshock wave energy [13, 15, 24] or using a method to preventthe shock waves from reaching the target muscles [16, 21,22]. Differently from pharmacological studies, the criticalissue concerning physical treatments such as shock wavesis the difficulty in making the placebo treatment actuallyeffective.Howcredible can a shockwave treatment bewithoutshock waves? Reasonably it could be argued that the absenceof clinical effects after the placebo treatment may be theconsequence that some patients guessed that they were notsubjected to an effective treatment. This obviously limits thevalue of the results obtained in the placebo arm and doesnot allow estimating the amount of placebo effect in the realtreatment arm. Furthermore, in all the placebo controlledstudies but one [24] the same patients received the placebotreatment in the first place and then the real treatment. Insuchway, patients could not only have suspected to have beentreated with placebo during the first treatment, but also haveprobably realized that they had been treatedwith shockwavesduring the second treatment.

10. Conclusions

Shock waves seem to be useful in treating muscle hypertoniain UMNS patients. The more consistent and encouragingresults were obtained in CP patients with both FSWT andRSWT and in the distal upper limb muscles of adult strokepatients using FSWT. However, we believe that up to now thebiological effects of shockwaves onmuscle hypertonia cannotbe clearly separated from a placebo effect. New solutions areneeded to address this issue.

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper.

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