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Pare, 63 (1995) 127-133 127{, 1995 Elsevier Science B.V. All rights reserve d 0304-3959/95 / 09.50

PAIN 29

R eflex sym pathet ic dystrophy changing concep ts and taxonom yM . S t a n t o n - H i c k s ~ * , W . J ~i nig b , S . H a s s e n b u s c h c, J . D . H a d d o x r, R . B o a s ~ a n d P . W i l s o n dPain Management Center, CTet'eland Clinic Foundation, Cleveland, OH 44195 (USA), t, Physiologisches blstitut, 2300 Kiel (Germany),

Department o f Neurosurgery, M.D. Anderson Cancer Center, Houston, TX 77030 (USA), J Department o f Anesthesiology, Mayo Clinic, Rochester,MN 55005 (USA), ' Section of Anaesthesia, University of Auckland, School of Medicine, Auckland (New Zealand) and I Pain Management Center,

Emory Clinic, Atlanta, GA 30322 (USA)(Received 24 Dece mber 1993, revision received 17 August 1994, accepted 5 May 1995)

S u m m a r y W e p r e s e n t a r e v i s e d t a x o n o m i c s y s t e m f o r d i s o r d e r s p r e v i o u s l y c a l l e d r e f l e x s y m p a t h e t i c d y s t r o p h y( R S D ) a n d c a u s a l g ia . T h e s y s t em r e s u l t e d f r o m a s p e c ia l c o n s e n s u s c o n f e r e n c e t h a t w a s c o n v e n e d o n t h i s t o p i c a n dis b a s e d u p o n t h e p a t i e n t s h i s to r y , p r e s e n t i n g s y m p t o m s , a n d f i n d i n g s a t t h e t i m e o f d i a g n o si s . T h e d i s o r d e r s a r eg r o u p e d u n d e r t h e u m b r e l l a t e r m C R P S : c o m p l e x r e g io n a l p a i n s y n d r o m e . T h is o v e ra l l t e r m , C R P S , r e q u i r e s th ep r e s e n c e o f r e g i o n a l p a i n a n d s e n s o r y c h a n g e s f o l l o w i n g a n o x i o u s e v e n t. F u r t h e r , t h e p a i n i s a s s o c i a t e d w i t hf i n d i n g s s u c h a s a b n o r m a l s k i n c o l o r , t e m p e r a t u r e c h a n g e , a b n o r m a l s u d o m o t o r a c ti v it y , o r e d e m a . T h e c o m b i n a t i o no f t h e s e f i n d i n g s e x c e e d s t h e i r e x p e c t e d m a g n i t u d e i n r e s p o n s e t o k n o w n p h y s i c a l d a m a g e d u r i n g a n d f o l l o w i n g th ei n c i ti n g e v e n t . T w o t y p e s o f C R P S h a v e b e e n r e c o g n i z e d : t y p e I , c o r r e s p o n d s t o R S D a n d o c c u r s w i t h o u t ad e f i n a b l e n e r v e l e si o n , a n d t y p e I I , f o r m e r l y c a ll e d c a u s a l g ia r e f e r s t o c a s e s w h e r e a d e f i n a b l e n e r v e l e s i o n isp r e s e n t . T h e t e r m s y m p a t h e t i c a l l y m a i n t a i n e d p a i n ( S M P ) w a s a l s o e v a l u a t e d a n d c o n s i d e r e d t o b e a v a r i a b l ep h e n o m e n o n a s s o c i a t e d w i t h a v a r i e t y o f d i s o r d e r s , i n c l u d i n g C R P S t y p e s I a n d I I . T h e s e r e v i s e d c a t e g o r i e s h a v eb e e n i n c l u d e d i n t h e 2 n d e d i t i o n o f th e IASP Classification of Chronic Pain Syndromes

K e y w o r d s : R e f l e x s y m p a t h e t i c d y s t r o p h y ; C a u s a l g i a ; C o m p l e x r e g i o n a l p a i n s y n d r o m e ; S y m p a t h e t i c a l l y m a i n t a i n e dp a i n

i s tor ica l developm entE v o l u t i o n o f t h e t h e r a p y a n d c o n c e p t u a l u n d e r -

s t a n d in g o f r e f l ex s y m p a t h e t i c d y s t r o p h y ( R S D ) h a sb e e n a s d y n a m i c a s t h e s y n d r o m e i t s e l f . S i n c e t h e f i r s td e s c r i p t i o n o f c a u s a lg i a i n s o l d i e r s s u s ta i n i n g n e r v ei n j u r ie s ( M i t c h e l l e t a l. 1 8 6 4 ) i n t e r p r e t a t i o n s o f t h em e c h an i st Ji c a s p e c t s a n d t r e a t m e n t m o d a l i t i e s h a v e b e e nv a r i e d a n d c o n t e n t i o u s . L e r i c h e ( 1 9 3 9 ) d e v e l o p e d t h ev i c i o u s c i rc l e h y p o t h e s i s w h i c h L i v i n g s t o n (1 9 4 3 ) ex -

p a n d e d t o a c o n c e p t o f a b n o r m a l f i r i n g in s e lf - s u s ta i n -i n g l o o p s i n th e d o r s a l h o r n p r o v o k e d b y a n i r r i t a ti v ef o c u s i n s m a l l n e r v e e n d i n g s o r m a j o r n e r v e t r u n k s .

* Corresponding author: Michael Stanton-Hicks, MB.BS, Dr. reed.,FRCA, FACPM, Director, Pain Management Center, U-21, TheCleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH44195, USA. Tel.: (216)445-9559; FAX: (216)444-9248.

T h i s w o u l d i n t u r n a c t i v a t e c e n t r a l p r o j e c t i o n f i b e r s ,g i v in g r i se t o p a i n . T h e t e r m R S D w a s u s e d t o e n c o m -p a s s t h e s e p a i n d i s o r d e r s u n d e r t h e s u p p o s i t i o n t h a ts y m p a t h e t i c h y p e r a c t i v i t y is i n s o m e w a y i n v o l v e d i nt h e a b n o r m a l a c t i v i t y a t t h e p e r i p h e r y . ( E v a n s 1 9 46 ).S u p p o r t f o r t h i s c o n c e p t w a s p r o v i d e d b y t h e i m p r o v e -m e n t o f t e n o b t a i n e d w i t h s y m p a t h e t i c b l o c k s . B o n i c a ,i n p a r t i c u l a r , a d v a n c e d n e r v e b l o c k s t o a s t a n d a r dt h e r a p y w i t h h is d e t a i l e d a c c o u n t s o f t h e s y n d r o m ev a r i a b l e s a n d w i t h s p e c i a l e m p h a s i s u p o n t h e o b j e c t i v ea s s e s s m e n t o f t h e e f f i c a c y o f b l o c k t e c h n i q u e s ( B o n i c a1 9 9 0 ) . V a r i o u s p r o c e d u r e s s u c h a s s y m p a t h e t i c g a n -g l i o n b l o c k s , i n t r a v e n o u s r e g i o n a l a d r e n o c e p t o r b l o c k sh a v e b e c o m e t h e m a i n s t a y f o r t r e a t m e n t a n d f a c i l it a -t i o n o f e x e r c is e s . H o w e v e r , th e i m p r o v e d a w a r e n e s sa n d e x p e r t i s e a n d c a r e o f R S D - l i k e c a s e s a r i s i n g f r o mp a i n c l i n ic s w o r l d w i d e y i e l d e d e v i d e n c e o f a l a rg e n u m -b e r o f p a t i e n t s w h o w e r e d i f f i c u lt t o c a t e g o r i z e i n t o

SSDI 0304-395 9( 95 )00110-7

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128one or other of the various syndrome patterns, e.g.,RSD/causalgia/SMP, who did not necessarily re-spond to sympathetic blocks, and who evidenced nophysiological confirmation of sympa thetic hyperactivity.

P r o b l e m s w i t h t h e p r e v i o u s t a x o n o m yConfusion exists with regard to what is meant byRS D (J~inig 1991a; Wilson 1992). The te rm R SD has

lost usefulness as a clinical designation because it hasbeen used so indiscriminately that it is no longer clearwhat it means. The link between nociceptive neuronsand postganglionic sympathetic activity is inconstant,with sympathetic blocks sometimes altering the syn-drome at least temporarily and sometimes not (Devoret al. 1991; J~inig 1985, 1990a, 1992a; Blu mberg 1992a).Adrenergic mechanisms in some form do appear to beinvolved in some of these conditions but measurementsof sympathetic responses have often shown normalresults (Campbell 1992; Roberts 1992). The term RSDis used imprecisely as it refers to changes in soft tissuewhich may or may not depend upon the sympatheticnervous system, may not be the consequence of areflex, and may occur later in the disorder.

Because of present confusion and to revise the ter-minology and criteria related to RSD, a Special Con-sensus Workshop was held in Orlando, Florida, from31 October to 3 November 1993. The goals of theWorkshop were to examine the terms RSD, causalgia,sympathetically maintained pain (SMP) and sympathet-ically independent pain (SIP); to consider the need forrevision of the IASP Taxonomy to define the variousassociated symptoms and findings of the disorders; todetermin e the value and role of various tests in thediagnosis of these disorders, and to develop an algo-rithm for diagnosis. It was felt that the present taxo-nomic entities were inadequate and revised categorieswere developed which are presented herein. TheWorkshop was organized by the first two authors ofthis paper and the Workshop members are listed inTable I.TABLE lMEMBERS OF CONSENSUS CONFERENCEGroup l: LaboratoryCorrelatesWilfrid J~inig (Group Leader), Gary Bennett, Nagy Mekhail,Donald Price, Gabor Racz, William J. Roberts, Wen-Hsien Wu.Group II: Signs and SymptomsJ. David Haddox (Group Leader), James N. Campbell, MartinKolzenburg, P. Prithvi Raj, Michael Stanton-Hicks, Rail Baron.Group III: Differential DiagnosisRobert Boas (Group Leader), Helmut Blumberg, SamuelJ. Hassenbusch, Harold Merskey, Robert T. Wilder.Group IV: AlgorithmPeter R. Wilson (Group Leader), Marshall Bedder, EdwardCovington, Philip Low, Richard Rauck.

o n s i d e r a t i o n s i n t h e f o r m a t i o n o f t h e t a x o n o m yThis new classification attempts to retain the central

features of the existing terms RSD/causalgia/SMPwhile also acknowledging a lack of scientific under-standing of these disorders. Attempts were made todevelop descriptions and criteria that would cover themain clinical categories. The descriptions were de-signed to provide information about differential diag-nosis and to provide a new classification consistentwith the current revision of the 1ASP classification ofchronic pain syndromes (IASP 1994).

Since the pathology for these disorders remainsunclear, any method based upon presumed causes ormechanisms was deemed unworkable for this disorder(J~nig 1990b, 1992c, 1994; J~inig et al. 1992b, J~inig andStanton-Hicks, 1995. As a result, the classification wasbased upon a descriptive method rather than uponpathophysiology as presently understood. In this man-ner, the new classification should be able to standdespite any scientific findings that may allow for modi-fication and identification of subgroups in the future.

Princ ip les of descr ip t ionTo achieve agreement among the participants in this

evaluation a linguistic convention was adopted for thediscussions that led to this report corresponding to theapproach used by the IASP Task Force on Taxonomy(IASP 1994, pp. X-XII). Since there is dissatisfactionwith the term RSD and a lack of conclusive evidenceas to the manner in which the sympathetic nervoussystem is involved in these disorders, the te rm sym-pathetic has been avoided in the definition. Termsimplying a mechanism that was inherently speculativewere precluded in describing this group of disordersand their definitions.

Pain is the sine qua non for diagnosis. The termspon tane ous indicates that the pain arises without

external cause. Evoked pain can be described as allo-dynia, which is pain resulting from a normally non-noxious stimulus, or hyperalgesia, which includes allo-dynia and is also pain that is disproportionate to anoxious stimulus. These terms are employed since eachprovides information about pain in relation to a stimu-lus (Price et al. 1989, 1992; Bonica 1990). However, theterms were used in conjunction with each other, sepa-rated by a slash mark, signifying that either term maybe used according to the situation.

Since tremor and dystonia as well as weakness maybe found in these patients, the term impai rmen t ofmotor funct ion is used to encompass such abnormali-ties. When two clinical signs are joined by or , if eithersign is present or both, the condition of the statementis satisfied.

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O s t e o p o r o s i s , a s i g n t h a t p r o v i d e d a n e p o n y m( S u d e c k s a t r o p h y ) th a t i n f l u en c e d E u r o p e a n t a x o n o m yb u t w h i c h i s i n c o n s i s t e n t a n d o c c u r s i n o n l y a s m a l lp e r c e n t a g e o f ca s e s . I t is t h e r e f o r e n o t i n c l u d e d a s ap a r t i c u l a r c l i ni c al f e a t u r e o f C R P S .

v e r v ie w o f th e n e w t a x o n o m yW e c h o s e c o m p l e x r e g i o n a l p a i n s y n d r o m e ( C R P S )

a s a n o v e r a l l t e r m f o r t h e s e g r o u p s . T h e w o r d c o m p l e xw a s u s e d t o d e n o t e t h e v a r i e d c l i n i c a l p h e n o m e n af o u n d i n e a c h g r o u p i n a d d i t i o n t o p a i n . T h e regionald i s t r ib u t i o n o f t h e s y m p t o m s a n d f i n d i n g s i s a h a l l m a r ko f th e s e d i is o r d er s . T h e y u s u a l l y a f f e c t t h e d i s t a l p a r t o fa li m b b u t r a r e l y o c c u r o n t h e t o r s o o r f a c e a n d m a ys p r e a d t o o t h e r b o d y a r e a s ( B e n t l e y 1 9 8 0 ) . Pain o fc o u r s e , i s t h e c a r d i n a l s y m p t o m f o r t h i s g r o u p i n g . T a b l eI I s ho w s t h e e s s e n t i a l c r i t e r ia f o r t w o t y p e s o f C R P S .

T h e d e f i n i t io n s f o r t h e t w o t y p e s o f d i s o r d e r s u n d e rt h e h e a d i n g o f C R P S w e r e d e v e l o p e d t o b e s e l f- e x -p l a n a t o r y f o r t h e m o s t p a r t . T h e m o s t c o m m o n d i s o r -d e r w i t h in t h e s y s t e m i s t h e e n t i t y t h a t h a s b e e n m o s tt y p ic a l ly k n o w n a s R S D . T h i s g r o u p h a s b e e n t e r m e dC R P S t y p e I a n d c o n s i d e r a b l e e f f o r t w a s u s e d t od e f i n e t h e t y p i c a l p a t i e n t i n t h i s g r o u p b u t s t i l l a l l o wf o r t h e v a r i a b il i ty i n s y m p t o m s a n d f i n d i ng s t h a t is s e e n

T A B L E I ID R A F T C R I T E R I A : C O M P L E X R E G I O N A L P A I N S Y N -D R O M E ( C RP S )A t e r m d e s c r i b i n g a v a r i e t y o f p a i n f u l c o n d i t i o n s f o l l o w i n g i n j u ryw h i c h a p p e a r s r e g i o n a l ly h a v i n g a d i st a l p r e d o m i n a n c e o f a b n o r m a lf i n d in g s , e x c e e d i n g i n b o t h m a g n i t u d e a n d d u r a t i o n t h e e x p e c t e dc l i n ic a l c o u r s e o f t h e i n c i t i n g e v e n t o f t e n r e s u l t i n g i n s i g n i f ic a n ti m p a i r m e n t o f m o t o r f u n c t io n , a n d s h o w i n g v a r i a b le p r o g r e s s i o n o v e rt i m e .C R P S t y p e I ( R S D )

1 . T y p e I i s a s y n d r o m e t h a t d e v e l o p s a f t e r a n i n i t i a t i n g n o x i o u se v e n t .2 . S p o n t a n e o u s p a i n o r a l l o d y n i a / h y p e r a l g e s i a o c c u r s , i s n o t l i m -i t e d t o t h e t e r r i t o r y o f a s i n g l e p e r i p h e r a l n e r v e , a n d i s d i s p r o p o r -t i o n a t e t o t h e i n c i t i n g e v e n t .3 . T h e r e i s o r h a s b e e n e v i d e n c e o f e d e m a , s k i n b l o o d f lo wa b n o r m a l i t y , o r a b n o r m a l s u d o m o t o r a c t i v i t y i n t h e r e g i o n o f t h ep a i n s i n c e t h e i n c i t i n g e v e n t .4 . T h i s d i i a g n o si s i s e x c l u d e d b y t h e e x i s t e n c e o f c o n d i t i o n s t h a tw o u l d o t h e r w i s e a c c o u n t f o r t h e d e g r e e o f p a i n a n d d y s f u n c t i o n .

C R P S t y p e I I ( C a u s a l g i a )1 . T y p e l I i s a s y n d r o m e t h a t d e v e l o p s a f t e r a n e r v e i n j ur y .S p o n t a n e o u s p a i n o r a l l o d y n i a / h y p e r a l g e s i a o c c u r s a n d i s n o tn e c e s s a r i l y l i m i t e d t o t h e t e r r i t o r y o f t h e i n j u r e d n e r v e .2 . T h e r e i s o r h a s b e e n e v i d e n c e o f e d e m a , s k i n b lo o d f lo wa b n o r m a l i t y , o r a b n o r m a l s u d o m o t o r a c t i vi ty in t h e r e g i o n o f t h ep a i n s i n c e t h e i n c i t i n g e v e n t .3 . T h i s d i a g n o s i s i s e x c l u d e d b y t h e e x i s t e n c e o f c o n d i t i o n s t h a tw o u l d o t h e r w i s e a c c o u n t f o r t h e d e g r e e o f p a i n a n d d y s f u n c t i o n ,

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f r e q u e n t l y i n t h e s e p a t i e n t s ( B l u m b e r g 1 98 8, 1 9 91 ,1992b, 1993; Wil lner 1993) .

O n t h e b a s i s o f c o m m o n u s a g e , c a u s a lg i a w a s co n -s i d e r e d t o r e f e r t o a n i m p o r t a n t a l t e r n a t i v e g r o u p o fp a t i e n t s . T h e d e s c r i p t i o n o f C R P S t y p e I I is i n t e n d e dt o c o v e r p a t i e n t s f i t t i n g t h e c la s s i c a l d e s c r i p t i o n o fc a u sa lg i a (R ic h a rd s 1967; B on ic a 1979 , 1990) . Th en u m b e r o f t h e s e p a t i e n t s j u st i f ie s a s e p a r a t e g r o u p i n ga l t h o u g h t h e y a r e f o u n d l es s f r e q u e n t l y .

T h e n o m e n c l a t u r e f o r C R P S t y p e s I a n d I I a l lo w sf o r e i t h e r c o n t i n u o u s ( o r s p o n t a n e o u s ) p a i n o r e v o k e dp a i n s u c h a s a l l o d y n i a o r h y p e r a l g e s i a a l t h o u g h t h o s ea r e l i k e l y t o b e c o n c u r r e n t i n m o s t a r e a s ( P r i c e 1 98 9,1 99 2; B o n i c a 1 9 9 0 ). I t r e m a i n s t o b e s e e n w h e t h e rs o m e p a t i e n t s m i g h t n o t f u l f i l l t h e c r i t e r i a f o r C R P St y p e I o r t y p e I I a n d w h e t h e r t h e y m i g h t r e p r e s e n t a3 r d t y p e C R P S , n o t o t h e r w i s e s p e c i f i e d ( N O S ) .

M o t o r s y m p t o m s a n d f i n d i n g s h av e n o t b e e n i n -c l u d e d a s c r i t e r i a i n t h i s c l a s s i f i c a t i o n a l t h o u g h i t s h o u l db e n o t e d t h a t t h e y c an i n c l u d e t r e m o r , d y s t o n i a a n dw e a k n e s s i n m a n y p a t i e n t s ( J a n c o v i c 1 9 8 8; S c h w a r t z -ma n 1990 ; D e usc h l e t a l . 1991 ; B ha t i a e l a l . 1993 ) . Ther o l e o f s y m p a t h e t i c b l oc k s i n d i a g n o s is h a s b e e n m i n i -m i z e d . E a c h o f t h e c a t e g o r i e s u n d e r t h e u m b r e l l a t e r mC R P S c o u l d b e d i v i d e d i n t o p a t i e n t s r e s p o n s i v e a n du n r e s p o n s i v e t o s y m p a t h e t i c b l o c k s .

I n a s i m i l a r m a n n e r , t h e s t r u c t u r e a l lo w s a n d e v e ne n c o u r a g e s t h e p o s s i b i l i t y o f i d e n t i f y i n g s p e c i f i c s u b -t y p e s f o r C R P S t y p e s I o r I 1 . F o r e x a m p l e , a p a t i e n tg r o u p m i g h t b e i d e n t i f i e d i n w h i c h a l l t h e p a t i e n t s m e tt h e c r i t e r ia f o r C R P S t y p e I a n d u n i f o r m l y h a d as p e c i f i c a d d i t i o n a l s y m p t o m o r f i n d i n g . I f s u c h a s u b -g r o u p e i t h e r b e h a v e d d i f f e r e n t l y o r w a s t r e a t e d d i f f e r -e n t l y t h a n t h e m a i n t y p e I g r o u p , t h e c l a s s i f i c a t i o nc o u l d b e m o d i f i e d t o a l l o w a s p e c i f i c s u b g r o u p . I t w a sn o t , h o w e v e r , f e l t u s e f u l t o s p e c i f y d i f f e r e n t s t a g e s f o re a c h t y p e . I t s t i l l r e m a i n s p o s s i b l e t h a t s t a g e s b a s e du p o n t h e s e v e r i t y o f th e d i s o r d e r o r t h e t i m e c o u r s e o ft h e d i s o r d e r , m i g h t h a v e u t i li t y i n t h e t h e r a p y o f t h e s ep a t i e n t s i n t h e f u t u r e .

T h e r e is s o m e e v i d e n c e t h a t s o m e p a t i e n t s m i g h th a v e a p r e d i s p o s i t i o n t o t h e d e v e l o p m e n t o f R S D o rc a u s a l g i a . T h i s p o s s i b i l it y r e m a i n s u n c l e a r a n d t h e d e f i -n i t i o n s f o r C R P S t y p e s I a n d I I w e r e s p e c i f i c a ll y d e -s i g n e d w i t h o u t r e f e r e n c e t o t h e p o s s i b i li t y o f p r e d i s p o -s i t io n . E v i d e n c e i n a p a r t i c u l a r p a t i e n t o f a p o s s i b l ep r e d i s p o s it i o n t o th e d e v e l o p m e n t o f C R P S s h o u ldh a v e n o b e a r i n g u p o n t h e d i a g n o s i s a n d , a t t h e p r e s e n tt i m e , w o u l d n o t s u g g e s t t h e p o s s i b i l i ty o f a n a l t e r n a t i v ed i a g n o s i s o r a s p e c i a l s u b t y p e f o r t h e s e d i s o r d e r s .

T h e d e f i n i t i o n s o f b o t h C R P S t y p e s 1 a n d I I c o n t a i na n e x c l u s io n c r i t e r io n . T h i s w a s p r o v i d e d t o p r e v e n ti n c lu s i o n o f p a t i e n t s w i t h p a i n a n d f i n d i n g s a n a t o m i -c a ll y , p h y s i o lo g i c al l y , a n d t e m p o r a l l y p r o p o r t i o n a t e t os o m e f o r m o f i n ju r y a s w e l l a s t o e x c l u d e m y o f a s c i a lp a i n s y n d r o m e f r o m t h i s cl a s s if i c at i o n. T h e C R P S d i a g-

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n o s is i s p r e c l u d e d b y th e e x i s t en c e o f k n o w n p a t h o l o g yt h a t c a n e x p la i n th e o b s e r v e d s y m p t o m s an d d e g r e e o fp a i n . T h e o c c u r r e n c e o f s y m p t o m s a n d f i n d in g s i n t h ed i s t a l p a r t s o f a n e x t r e m i t y , o u t s i d e t h e t e r r i t o r y o f a ni n j u r e d n e r v e i s a h a l l m a r k o f t h e d e f i n i t i o n s . T h es y m p t o m s a n d f i n d in g s m i g h t a l s o o c c u r w i th i n t h et e r r i t o r y o f t h e n e r v e , b u t t h i s is n o t r e q u i r e d . T h e r e i sa s m a ll s u b s e t o f p a t i e n t s t h a t m i g h t h a v e s y m p t o m sa n d f i n d i n g s i n f o c a l a r e a s o f t h e b o d y t h a t a r e n o td i s t a l in t h e l i m b a n d a r e o u t s i d e t h e t e r r i t o r y o f t h ei n j u r e d n e r v e .

T h e c l in i ca l f e a t u r e s o f C R P S a r e t h e r e f o r e u s u a l lyf o u n d i n a n e x t r e m i t y , a r e m o r e m a r k e d d i s t a l l y a n ds h o w p r o g r e s s i v e c h a n g e s i n i n t e n s i t y w h i c h s p r e a dp r o x i m a l l y a n d v a r y w i t h t i m e . T h e d i s p r o p o r t i o n o fs y m p t o m s in r e l a t i o n t o t h e i n c i t i n g e v e n t i s a n o t h e rd i s t in g u i s h in g c h a r a c t e r i s t ic . E d e m a is im p o r t a n t i nt h e s e d i s o r d e r s , b u t i s n o t r e q u i r e d t o b e p r e s e n t a t t h et i m e o f d i a g n os i s . T h e o b s e r v a t i o n t h a t t h e s y m p t o m sa n d f i n d i n g s c a n s p r e a d t o o t h e r b o d y a r e a s h a s b e e na l l o w e d f o r in t h e d e s c r i p t i o n o f t h e s e d i s o r d e r s ( B e n t -l e y 1 9 8 0 ) . F o r e x a m p l e , a p a t i e n t w i t h d i a b e t i c n e u -r o p a t h y m i g h t h a v e p a i n a n d a l l o d y n i a in a g l o v e a n ds t o c k i n g d i s t r ib u t i o n , w e a k n e s s , a n d e v e n c o lo r c h a n g e sa t t i m e s . T h i s p a t i e n t , h o w e v e r , w o u l d n o t f i t t h ed i a g n o s is o f C R P S b e c a u s e t h e s y m p t o m s a n d f i n d i n g sw o u l d b e a t t r i b u t a b l e t o t h e d i a b e t i c n e u r o p a t h y a n dw i ll b e p r o p o r t i o n a l i n ti m e , d i s t r ib u t i o n , a n d c h a r a c t e rt o t h e u n d e r l y i n g d i s e a s e p r o c e s s .

C R P S t y p e I R S D )U n i l a t er a l a b a n d o n m e n t o f t h e t e rm s r e f le x s y m p a -

t h e ti c d y s t r o p h y a n d R S D w a s t h o u g h t by m a n y o ft h e c o n f e r e n c e p a r t i c i p a n t s t o b e u n r e a l i s t i c , g i v e nt h e i r c o m m o n , a l t h o u g h i m p r e c i s e , u s a g e . T o f a c i l i t a t et h is t r a n s it i o n , t h e t e r m R S D i s r e t a i n e d p a r e n t h e t i -c a ll y a f t e r t h e n e w t e r m i n o l o g y C R P S t y p e I ( R S D ) . I ti s i n t e n d e d t h a t t h i s t e r m w i l l n o l o n g e r b e u s e d a s ap r i m a r y d e s c r i p t o r b u t , w h e n i t i s u s e d , i t i s t o b eu n d e r s t o o d t h a t i t s u s e is t r a n s i t i o n a l a n d not anabbreviation fo r an outdated mechanistic term

I t s h o u l d b e n o t e d t h a t C R P S t y p e I ( R S D ) , t y p i -c a l ly , h a s d e e p , d i f f u s e p a i n t h a t is w o r s e w i t h l i m bd e p e n d e n c y ( o r t h o s t a t ic ) w h ic h m a y r e s p o n d t o s y m p a -t h e t i c b l o c k ( T a b l e I I ) . V a r i a b l e e t i o lo g i c a l f a c to r s c a ni n c l u d e r e p e t i t i v e m i n o r t r a u m a , o t h e r t r a u m a , s t r o k e ,i m m o b i l i z a t i o n , m y o c a r d i a l i n f a r c t i o n , a n d o v e r - s t r a i n( A s k e y 1 9 4 1 ; S t e i n b r o c h e r e t a l . 1 9 4 8 ; M o s k o w i t z e t a l .1958 ; Pa tma n e t a l . 1973 ; Low 1978) .

C R P S ty p e I I f o r m e r l y c a u s a l g i a )T h e s o l e d i f f e r e n t i a t i n g c r i t e r i o n b e t w e e n C R P S

t y p e I ( R S D ) a n d C R P S t y p e I I i s t h e p r e s e n c e o f a

k n o w n n e r v e i n j u r y . T r a d i t i o n a l l y , t h e s e i n j u r i e s i n -v o l v e l a r g e n a m e d n e r v e s , s u c h a s t h e m e d i a n o r s c i at i cn e r v e .

D i f f e r e n t i a l d i a g n o s i sT h e c o n c e p t o f r e g i o n a l it y is an i m p o r t a n t a s p e c t i n

t h e d i f f e r e n t i a l d i a g n o s i s . A l t h o u g h R S D a n d c a u s a l g i aa r e c o n s i d e r e d t y p i c a l ly t o b e d i s o r d e r s i n th e p e r i p h -e l y o f a l i m b , t h e d e f i n i t i o n o f C R P S a l l o w s th e p o s s i -b i l it y o f i n v o l v e m e n t i n a r e g i o n s u c h a s a s id e o f t h ef a c e o r a re g i o n o f th e t r u n k . S u b s e q u e n t e x t e n s io n o fp a i n b e y o n d t h e s i t e o f a n i n i t ia l l e s i o n , c h a n g e s i n s k i nb l o o d f l o w , e d e m a , a n d s u d o m o t o r c h a n g e s i n t h es u r r o u n d i n g a r e a s w o u l d m e e t t h e d e f i n i ti o n o f t y p e I I( c a u s a l g i a ) a n d c o u l d b e i n a n y r e g i o n o f t h e b o d y t h a ts u r r o u n d s t h e t e r r i t o r y o f a p e r i p h e r a l o r c r a n i a l n e r v e .

C r i t e r i a f o r t h e s e d i s o r d e r s d o n o t i n c l u d e m o t o rd y s f u n c t i o n a n d t h u s i t i s n o t r e q u i r e d f o r th e d i a g n o -s is . O n t h e o t h e r h a n d , m o t o r d y s f u n c t i o n i s s e e nf r e q u e n t l y i n t h e s e c o n d i t i o n s . T h i s m a y i n c l u d e w e a k -n e s s , d y s t o n i a , o r a li m i t e d a c t i v e r a n g e o f m o t i o n( Ja nc ov ic 1988 ; Sc hw a r t z ma n 1990 ; D e usc h l e t a l . 1991 ;B h a t i a 1 9 9 3 ) . T h i s f e a t u r e s h o u l d b e d i f f e r e n t i a t e df r o m p a s s i v e l im i t a t i o n o f m o t i o n w h i c h m i g h t m o r et y p ic a ll y r e p r e s e n t a fr o z e n j o in t r a t h e r t h a n m o t o rd y s f u n c t i o n p e r s e .

T h e d e f i n i t i o n o f c a u s a l g i a a l l o w s f o r l i m i t e d c o m b i -n a t i o n s o f t h e f o l l o w i n g a b n o r m a l i t i e s : e d e m a , s k i nt e m p e r a t u r e o r c o l o r c h a n g es , a n d s u d o m o t o r c h a n g e si n c o n j u n c t i o n w i t h a p a i n f u l n e r v e i n ju r y . O n e o r m o r eo f t h e s e s y m p t o m s a n d f in d i n g s m a y d o m i n a t e t h ec l i n ic a l p i c t u r e w i t h o n l y m i n i m a l e v i d e n c e o f o t h e r s .S i n c e th i s r e p r e s e n t s m u c h o f t h e v a r i e ty a m o n g t h e s ep a t i e n t s, t h e t e r m i n o l o g y h a s b e e n d e s i g n e d t o i n c l u d et h o s e p a t i e n t s t h a t h a v e a t le a s t o n e o f th e s e c h a r a c t e r -i s ti c s. I f t h e r e is p a i n s u c h a s a l l o d y n i a o r h y p e r a l g e s i awithout t h e o t h e r a b n o r m a l i t i e s ( e .g . , v a s c u l a r c h a n g e s ,s u d o m o t o r c h a n g e s , e d e m a ) , t h is is n o t C R P S . C o n -v e r s e l y , t h e t e r m C R P S i t s e l f i m p l i e s t h a t p a i n is a s in eq u a n o n o f t h e d i a g n o s i s . H o w e v e r , t h e r e i s a v e r ys m a l l g r o u p o f p a t ie n t s w i t h o u t p a i n b u t w i t h m a n y o ra l l t h e o t h e r c r i t e r i a f o r R S D o r c a u s a l g i a . F o r t h ep r e s e n t t h e s e p a t i e n t s w il l r e m a i n o u t s i d e t h e C R P Su m b r e l l a b u t m i g h t b e n e f i t f r o m a n a ly s i s in t h e f u t u r e .

I n t h e d i f f e r e n t i a l d i a g n o s i s o f t h e s e c o n d i t i o n s ,m a l i n g e r i n g a n d f a c t i t i o u s d i s e a s e is e x c l u d e d b y d e f i -n i t i o n . I t i s r e c o g n i z e d t h a t p a t i e n t s w i t h C R P S t y p e s Io r I I m a y w e ll h a v e p s y c h o l o g i c a l o r p s y c h i a t r i c d i s t u r -b a n c e s . T h e m e r e e x i s t e n c e o f s u c h p r o b l e m s d o e s n o t ,h o w e v e r , p r e c l u d e t h e d i a g n o s i s o f C R P S .

N e u r o p a t h i c p a i n i s f o u n d i n m a n y d i s o r d e r s i n c l u d -i ng C R P S t y p e s I a n d I I . T h u s , n e u r o p a t h i c p a i n l ik eS M P i s , m o r e s p e c i f i c a l l y , a p h e n o m e n o n o r c l i n i c a ld e s c r i p t o r t h a n a d i s o r d e r ( R o b e r t s 1 98 6). T h e t e r m

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n e u r o p a t h i c p a i n is es s e n t i a ll y a c l in i c al s y m p t o m ( p a i n )a s s o ci a te d w i t h a p r e s u m e d u n d e r l y i n g p a t h o p h y s i o lo g y( n e u r o l o g i c a l d a m a g e ) .

Other pa in problemsT h e c o n s e n s u s g r o u p w o u l d e n c o u r a g e c l i n i c i a n s t o

e m p l o y t h e ' n o t o t h e r w i s e s p e c i f i e d ( N O S ) ' c o d e s f r o mt h e I C D - 1 0 c l a s s i f i c a t i o n f o r t h o s e c a s e s n o t m e e t i n gt h e d i a g n o s t i c c r i t e r i a f o r C R P S t y p e s I a n d I I . O n es u c h e x a m p l e w o u l d b e ' l i m b p a i n , N O S ' . T h e I A S Ps y s t e m a l s o p r o v i d e s a c o d e f o r t h i s u n d e r t h e h e a d -i n g s : X I . 1 9 . p a i n i n t h e l i m b s , N O S : u p p e r l i m b ( s )2 X X . X X Z , a n d l o w e r l i m b ( s ) 6 X X . X X Z .

I t i s r e c o g n i z e d t h a t , i n s o m e c i r c l e s , p a i n i n t h eh a n d t h a i : i s n o t i n t h e C R P S g r o u p i n g m i g h t b el a b e l e d a s ' p a i n d y s f u n c t i o n s y n d r o m e ' . T h i s u s e s e e m sr e a s o n a b l e i n l i g h t o f t h e f a c t t h a t i t m e r e l y m a k e s a no b s e r v a t i o n a n d d o e s n o t d e n o t e a m e c h a n i s m o r a ne t i o l o g y .

131

Fig. 1. Relationship between SMP and selected painful conditions.This is meant to be a conceptual framework and the magnitude ofthe intersection between sets is not intended to represent a quantita-tive relationship. SMP may exist as an entity not associated with anyother condition. The list of associated conditions is not meant to be

exhaustive.

S P and neura lg iasT h e u s e o f s y m p a t h o l y t i c p r o c e d u r e s i n t h e p a s t h a s

c l o u d e d t h e d i ag n o s is o f R S D . C R P S h a s b e e n d e f i n e de n t i r e l y o n e l e m e n t s o f h i s t o r y ( e . g . , n o x i o u s e v e n t ) ,s y m p t o m s ( e . g . , p a i n ) , a n d c l i n i c a l f i n d i n g s ( e . g . , a l -t e r e d s u d o m o t o r a c t i v it y o r a b n o r m a l s k i n c o l o r a n dt e m p e r a t u r e ) . F o r th i s r e a s o n , s y m p a t h o l y t i c p r o c e -d u r e s h a v e n o r o l e i n t h e d i f f e r e n t i a l d i a g n o s i s o fC R P S t y p e s I o r I I p e r s e . S M P ( T a b l e l i d is t h a ta s p e c t o f p a i n t h a t i s m a i n t a i n e d b y s y m p a t h e t i c n e r -v o u s s y s t e m a c t iv i t y ( R o b e r t s 1 9 86 ). I t m a y b e a c o m p o -n e n t o f s e v e ra l d i f f e r e n t p a i n f u l c o n d i t i o n s b u t i s n o t ar e q u i r e m e n t o f a n y p a i n s y n d r o m e ( F i g. 1 ). A p o r t i o no f t h e p a i n o f n e u r a l g i a s a n d n e u r o p a t h i e s r e s u l t in g i nm u l t i p l e t y p e s o f p a t h o l o g y ( e .g . , h e r p e s z o s t e r ) m a y b er e s p o n s i v e t o s y m p a t h e t i c b l o c k ( B o n i c a 1 9 9 0 ) . A d d i -t i o n al l y , i n a n y i n d i v i d u a l p a t i e n t , a p o r t i o n o f t h e p a i nm a y b e s y m p a t h e t i c a l l y m a i n t a i n e d a n d a p o r t i o n s y m -p a t h e t i c a l l y i n d e p e n d e n t a s i n F i g . 2 . P a t i e n t A w h o s ep a i n is o n l y 2 0 - 3 0 m e d i a t e d b y t h e s y m p a t h e t i cn e r v o u s s y s t e m , w o u l d b e c o n s i d e r e d t o e x h i b i t m a i n l ys y m p a t h e t i c a l l y i n d e p e n d e n t p a i n ( S I P ) . P a t i e n t B ,w h o s e p a i n is 7 0 - 8 0 m e d i a t e d b y t h e s y m p a t h e t i c

TABLE IllSYMPATHETICALLY MAINTAIN ED PAIN SMP)

Pain that is maintained by sympathetic efferent innervation or bycirculating catecholamines.Note: SMP may be a feature of several types of painful conditionsand is not an essential requirement of any one condition.

n e r v o u s s y s t e m w o u l d b e c o n s i d e r e d t o e x h i b i t m a i n l y' s y m p a t h e t i c a l l y m a i n t a i n e d p a i n ( S M P ) ' . B e c a u s e i np a t i e n t s A a n d B b o t h ( S I P a n d S M P ) m a y o c c u r i n t h es a m e p a t i e n t e i t h e r o v e r l a p p i n g i n t y p e o r s e p a r a t e l y i nt h e e v o l u t i o n o f a si n g le d i s e a s e p r o c e s s , S M P s h o u l db e c o n s i d e r e d a s y m p t o m a n d n o t a s e p a r a t e d i a g n o s i s .

S M P c a n b e a s s o c i a t e d w i t h a n u m b e r o f d is e a s e sa n d a p o s i t i v e r e s p o n s e t o a s y m p a t h e t i c b l o c k s h o u l dn e i t h e r b e a f a c t o r in t h e n o m e n c l a t u r e o f t h e d i se a s en o r d e f i n e t h e d i s e a s e . A s a c o m p a r i s o n , d e p r e s s i o nm a y b e e x q u i s i te l y s u s c e p t i b l e t o e l e c t r o c o n v u l s i v et h e r a p y b u t i t w o u l d n o t b e r e a s o n a b l e t o r e f e r t o t h ed i s e a s e a s ' e l e c t r o d e f i c i e n t ' d i s e a s e . L i k e w i s e , l i t h i u mi s t h e m a i n s t a y o f t r e a t m e n t f o r m a n y p a t i e n t s w i t hm a n i a b u t i t w o u l d n o t b e r e a s o n a b l e t o d e f i n e m a n i a

a g n u e lf PainB

Fig. 2. A graphic representation of the relative contribution of SMPto overall pain in a given patient. Point A represents an individualwhose pain is predominantly sympathetically-maintained, whereasPoint B represents a situation in which the pain is only slightlyresponsive to sympatholytic intervention. Points A and B may repre-

sent different patients or the same patient at two different times.

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132as a lithium deficiency disease or as one which re-sponds to lithium.

o n c l u s i o n s

After review of the previous classification of RSDand similar disorders it was felt by the consensusgroup that a new more uniform and more clinicallybased system was needed. The acronym CRPS wasdeveloped to provide an umbrella structure for thesedisorders. CRPS type I was defined to correspond tothe common image of RSD and was based upon thedistribution of symptoms and signs such as on-goingpain allod ynia/ hype ralg esia vascular abnormalitiesedema and sudomotor changes. CRPS type II wasdefined to correspond to causalgia and based uponsimilar parameters. The definition of these disorders inthis manner allows a differential diagnosis of CRPSfrom other conditions. It is hoped that this system willhelp to provide clinical uniformity in the diagnosis ofpatients and allow better identification of importantsubgr oups fo r CRPS types 1 and II as well as possibleidentification of other CRPS types in the future.

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