Electroencephalography and Clinical Neurophysiology, 1 9 7 8 , 4 5 : 2 8 1 - - 2 8 5 © E l s e v i e r / N o r t h - H o l l a n d Scientific P u b l i s h e r s , Ltd.

281

Clinical n o t e A C N V S T U D Y IN A G R O U P O F P A T I E N T S WITH T R A U M A T I C H E A D I N J U R I E S * P.A. R I Z Z O , G. A M A B I L E , M. C A P O R A L I , M. S P A D A R O , M. Z A N A S I a n d C. M O R O C U T T I

H. Clinica delle Malattie Nervose e Mentali, UniversiM di Roma, R o m e (Italy) ( A c c e p t e d for p u b l i c a t i o n : M a r c h 31, 1 9 7 8 )

S t u d i e s carried o u t o n t h e c o n t i n g e n t negative v a r i a t i o n ( C N V ) have i n d i c a t e d t h a t this e v e n t is s u s c e p t i b l e t o m o d i f i c a t i o n s in c o n n e c t i o n w i t h psychological factors s u c h as a n x i e t y , stress, m o t i v a t i o n , a t t e n t i o n ( I r w i n et al. 1 9 6 6 ; L o w et al. 1 9 6 7 ; Walter 1 9 6 7 ; L o w a n d M c S h e r r y 1 9 6 8 ; M c C a l l u m a n d Walt e r 1 9 6 8 ; T e c c e 1 9 7 2 ) , a n d w i t h t h e use o f several psychotropic substances (Hablitz and Borda 1973; Tecce a n d Cole 1 9 7 4 ) . E x t e n s i v e research was carried o u t in r e c e n t years o n t h e a p p l i c a t i o n o f b o t h e v o k e d p o t e n t i a l s a n d CNVs, in t h e field o f p s y c h o - a n d neuropathology (Dongier and Bostem 1967; Knott a n d I r w i n 1 9 6 7 ; Floris et al. 1 9 6 8 ; M c C a l l u m a n d A b r a h a m 1 9 7 3 ; T i m s i t - B e r t h i e r et al. 1 9 7 3 ) . McCall u m a n d C u m m i n s ( 1 9 7 3 ) , in p a r t i c u l a r , r e c e n t l y obt a i n e d bilateral C N V r e c o r d s in p a t i e n t s s u f f e r i n g f r o m diffuse or focal lesions. T h e y n o t i c e d t h e prese n c e o f m o r p h o l o g i c a l C N V m o d i f i c a t i o n s in s u b j e c t s w i t h lesions localized in o n e h e m i s p h e r e , or even t h e i m p o s s i b i l i t y o f r e c o r d i n g t h e p h e n o m e n o n in case o f diffuse b r a i n i n v o l v e m e n t . O n t h e basis o f t h e s e a s s u m p t i o n s , w e t h o u g h t it w o r t h while t o s t u d y C N V d e v e l o p m e n t in a g r o u p o f p a t i e n t s w i t h t r a u m a t i c h e a d injuries, in o r d e r t o assess a n y possible c o r r e l a t i o n b e t w e e n o b j e c t i v e symptomatology, CNV parameters and psychometric tests. T w e n t y - s e v e n s u b j e c t s - - 12 m a l e s a n d 15 females aged 1 8 - - 5 6 ( m e a n age 31) were e x a m i n e d . All o f t h e m h a d s u f f e r e d f r o m s o m e serious t r a u m a t i c i n j u r y w i t h i m m e d i a t e o n s e t o f c o m a . T h e diagnosis, b a s e d o n clinical a n d i n s t r u m e n t a l criteria, was 'close b r a i n c o n t u s i o n ' in 20 cases, ' o p e n b r a i n c o n t u s i o n w i t h a d e p r e s s e d a n d c o m p o u n d f r a c t u r e o f t h e skull' in 1 case, ' a c u t e s u b d u r a l h a e m a t o m a w i t h b r a i n c o n t u s i o n - l a c e r a t i o n ' in 5 cases, ' o p e n s u b d u r a l h a e m a t o m a ' in 1 case. C o m a h a d an average d u r a t i o n of 15 days, r a n g i n g f r o m a m i n i m u m o f 2 days t o a m a x i m u m o f 90 days. N o n - s i g n i f i c a n t E E G a b n o r m a l i t i e s were o b s e r v e d d u r i n g r e c o r d i n g . -

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* This w o r k was s u p p o r t e d b y G r a n t 0 4 ] 7 4 0 0 2 3 3 , Consiglio N a z i o n a l e delle Ricerche.

Prior to r e c o r d i n g m e n t a l tests were p e r f o r m e d : (a) Wechsler--Bellevue I n t e l l i g e n c e Scale t o assess t h e intelligence q u o t i e n t (I.Q.) a n d t h e i n d e x o f m e n t a l deterioration, a c c o r d i n g t o Wechsler's f o r m u l a (Wechsler 1 9 4 4 ) . (b) B e n t o n visual r e t e n t i o n t e s t to assess t h e m n e s i c a n d p e r c e p t i v e abilities a n d visuom o t o r f u n c t i o n s . T h e p e r f o r m a n c e level in t h e l a t t e r test was e s t i m a t e d b y c a l c u l a t i n g t h e algebraical differences between the expected 'errors', taking into a c c o u n t b o t h I.Q. a n d age, a n d t h o s e actually m a d e by the patients under examination. All p s y c h o m e t r i c e x a m i n a t i o n s a n d C N V recordings were p e r f o r m e d in all s u b j e c t s w h e n t h e n e u r o p s y c h o l o g i c a l c o n d i t i o n s c o u l d be c o n s i d e r e d as well stabilized, a n d always a f t e r at least 5 m o n t h s f r o m t r a u m a . Fig. 2 s u m m a r i z e s t h e m o s t i m p o r t a n t data r e f e r r e d to each s u b j e c t u n d e r investigation. T h e d a t a o f d i f f e r e n t p a r a m e t e r s in s u b j e c t s w i t h h e a d injuries were c o m p a r e d w i t h t h e same d a t a obt a i n e d f r o m a p o p u l a t i o n o f 80 n o r m a l s u b j e c t s (Fig. 1). S u c h c o n t r o l s (52 males a n d 28 females), all s t u d e n t s or research w o r k e r s aged 1 9 - - 4 5 (average age 30) were selected b y m e a n s o f t h e M.P. t e s t o f E y s e n c k a n d t h e I P A T o f Cattel. All s u b j e c t s w i t h high scores o f a n x i e t y a n d n e u r o t i c i s m were elimin a t e d . S u b j e c t s w h o usually c o n s u m e d p s y c h o t r o p i c drugs or a l c o h o l , w h o were or h a d b e e n u n d e r p s y c h o t h e r a p y , w h o were or h a d b e e n in a p s y c h i a t r i c clinic, were e l i m i n a t e d . F o r C N V r e c o r d i n g , a t e c h n i q u e similar to t h a t initially d e s c r i b e d was used. T h e s u b j e c t was invited t o sit in an a n a t o m i c a l a r m c h a i r in a partially s o u n d p r o o f a n d semi-dark r o o m . T h e E E G was r e c o r d e d t h r o u g h 5 silver-silver c h l o r i d e e l e c t r o d e s : 2 were placed a l o n g t h e m i d l i n e , Fz 4 c m a b o v e t h e glabella, a n d C z o n t h e vertex. T h e 2 r e f e r e n c e e l e c t r o d e s were placed o n t h e m a s t o i d processes and d i r e c t l y c o n n e c t e d t o F z. T h e Cz e l e c t r o d e was r e f e r r e d t o t h e c e n t r a l t e r m i n a l of a 25 k ~ p o t e n t i o m e t e r c o n n e c t e d to Fz a n d t h e m a s t o i d e l e c t r o d e s , as used b y M c C a l l u m a n d Walter ( 1 9 6 8 ) t o a t t e n u a t e C N V c o n t a m i n a t i o n b y ocular p o t e n t i a l s . A f u r t h e r g r o u n d e l e c t r o d e was p l a c e d o n t h e ear lobe.

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Vertical eye m o v e m e n t s (EOGs) were r e c o r d e d with electrodes above and below the left eye. The e l e c t r o m y o g r a m (EMG) o f e x t e n s o r pollicis longus o f the right forearm was r e c o r d e d with 2 disc electrodes. All these electrodes were fixed to the skin by a special c o n d u c t i n g paste and were c o n n e c t e d to the i n p u t of a 1 2 ~ h a n n e l pen-recorder, m o d i f i e d to provide an 8 sec t i m e constant. A m p l i f i e r bandpass settings were 0 . 1 1 - - 5 0 c/sec. The analogue data were stored on-line on a magnetic tape-recorder. These data were s u m m a t e d

on-line and off-line with an averager ( C A T 1000 M n e m o t r o n 1024 points). The impulses which triggered the different stimuli were delivered by a programmable pulse generator. Analysis time was 4 sec. The c o n d i t i o n i n g and imperative stimuli were, respectively, a flash lasting 100 psec ($1) and, after 1500 msec, a sound lasting 600 msec, at a f r e q u e n c y of either 200 Hz or 700 Hz. A push b u t t o n was placed in the preferred hand o f the subject and he was invited to push it as rapidly as he c o u l d on hearing the 700 Hz sound ( e x e c u t i o n of the task caused the sound signal to stop). R e c o r d i n g only

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Fig. 2. Mean values of different CNV parameters in c o n t r o l subjects (N) and in subjects with head injuries (P). started after an initial period o f 10 min, during which the subject a c c u s t o m e d himself to the task. A sequence of 25 stimuli was administered and f r o m the responses 12 were chosen by eliminating those contam i n a t e d by eye m o v e m e n t s or blinking. The 12 events were c o n v e y e d to the C A T for averaging and displayed on an X-Y plotter. All data were c o n v e y e d to a 1106 Univac c o m p u t e r for study of various parameters and for statistical processing. In order to q u a n t i t a t e and define the amplitude and m o r p h o l o g y o f the wave, the following parameters were systematically considered: ( a ) l a t e n c y ( c o m p u t e d in msec f r o m the p o i n t at which the d e f l e c t i o n s u b s e q u e n t to the visual evoked potential (VEP) reached the baseline d e t e r m i n e d by an average of the E E G activity over 500 msec prior to $1); (b) rise t i m e of the curve measured in msec and corresponding to the time f r o m the end o f the latent period to the m a x i m u m peak; (c) m a x i m u m peak of the wave (in pV, c o r r e s p o n d i n g to m a x i m a l negativity); (d) m a x i m u m peak latency (in msec, f r o m the beginning o f $1 ); (e) decay time (in msec, f r o m maxim u m peak to onset of $2); (f) area o f CNV (in I/V 2,

f r o m the onset of peak to the onset of $2 ). The post-imperative negative variation ( P I N V ) w a s also evaluated, i.e., the delay of return o f the EEG tracing to the isoelectric line after $2. This was considered as significant when it lasted m o r e than 2 sec, in line with Chouinard et al. (1975). The c o m p a r i s o n of data f r o m patients and controls shows that the amplitude as well as the m a x i m u m peak latency and CNV global area were smaller in the subjects with head injuries. With S n e d e c o r ' s F test, o n l y a significant difference (P < 0.01) in the total wave area was f o u n d b e t w e e n the 2 groups (Figs. 1 and 2). In 7 patients a large PINV could be observed. On the o t h e r hand, non-significant correlations were o b t a i n e d b e t w e e n the I.Q., B e n t o n ' s test, the mental d e t e r i o r a t i o n index and CNV parameters. It is interesting to n o t e that the 7 subjects with a conspicuous PINV were those who m a d e the largest n u m b e r o f errors in B e n t o n ' s test (a significant correlation was f o u n d with X2 test) (Fig. 3), whereas no correlations with the I.Q. and mental d e t e r i o r a t i o n index emerged. The i n t e r p r e t a t i o n o f these findings is far from

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easy, in view o f the m a n i f o l d factors interfering with CNV d e v e l o p m e n t . In agreement with the results r e p o r t e d by McCallum and C u m m i n s (1973), it may be assumed, however, that the smaller a m p l i t u d e of the CNV in subjects with head injuries is traceable to a primary or secondary i m p a i r m e n t of cortical and subcortical structures involved in the d e v e l o p m e n t of CNV. As to the PINV, f o u n d in 7 o f the e x a m i n e d subjeets, it is a well-known abnormality in the psychopathological field, in p s y c h o t i c diseases and in serious psychoneurosis. Nevertheless, recent investigations ( D e l a u n o y et al. 1975; Gauthier and G o t t e s m a n n 1976) d e m o n s t r a t e d that PINV can appear in normal subjects under stress conditions; since it disappears u n d e r basal conditions, the authors suggest that this a b n o r m a l i t y o f the terminal phase o f the CNV reflects a transient alteration of the psychopathological state of the subject due to stress. On the basis of these findings we r e c o r d e d the CNV of the 7 subjects showing this bioelectric abnormality during 2 different sessions (the second being 30--60 days after the first), and the p h e n o m e n o n

reappeared constantly in all 7 subjects. The rather small n u m b e r (7 of 27) of subjects w h o presented the PINV prevents us f r o m drawing definite conclusions. On the o t h e r hand, the c o r r e | a t i o n existing b e t w e e n the PINV and B e n t o n ' s test m a y be a c c o u n t e d for if one considers that this test is generally regarded as one o f the m o s t effective clinical instruments for selectively estimating mnesic and perceptive abilities and v i s u o - m o t o r functions. The Wechsler--Bellevue Intelligence Scale is instead based on the survey of a very large n u m b e r of factors that m a y m u t u a l l y affect the final result. It is probable t h e r e f o r e that s o m e specific deficits and typical sequelae of organic brain lesions may be masked by high scores o b t a i n e d in o t h e r subjects, for the correct p e r f o r m a n c e of which a c o m p l e t e physical integrity is n o t required. In conclusion, it m a y be assumed that in the sequelae of serious brain trauma the late restoration of physiological, bioelectric and m e t a b o l i c functional c o n d i t i o n s o f the cerebral c o r t e x probably underlies the PINV.

CNV AFTER HEAD INJURIES Summary CNVs were studied in a group of 27 subjects with traumatic head injuries followed by protracted coma. Before CNV recording, all patients were subjected to Wechsler--Bellevue Intelligence Scale and to Benton's visual retention test. The findings were compared with those obtained from 80 normal subjects. A statistically significant decrease was observed in the CNV area in the group with traumatic lesions. No correlation could be found between CNV parameters and the results of the mental tests. In 7 of the subjects who presented the highest percentage of errors in Benton's test, a large post-imperative negative variation was observed.

R6sum6 Etude de la variation contingente ndgative dans un groupe de patients traumatisds craniens

La VCN a 6t~ 6tudi6e chez 27 sujets traumatis6s craniens apr~s un coma prolong6. Avant enregistrement de la VCN, tous les patients furent soumis aux tests d'6chelle d'intelligence de Wechsler--Bellevue et de r6tention visuelle de Benton. Les r6sultats ont 6t6 compar6s ~ ceux obtenus chez 80 sujets normaux. La surface de la VCN s'est r6v616e significativement inf6rieure chez les traumatis6s. En revanche, aucune corr61ation n'a pu ~tre trouv6e entre les param~tres de la VCN et les r6sultats des tests. Chez 7 sujets, qui pr6sent~rent le plus haut pourcentage d'erreurs dans le test de Benton, une ample variation n6gative post-imp6rative rut observ6e.

References Chouinard, G., Annable, L., Dubrovsky, B. and Dongier, M. Post-imperative negative variation (PINV) in ambulatory schizophrenic patients. Comprehens. Psychiat., 1975, 16: 457--460. Delaunoy, J., Timsit-Berthier, M., Rousseau, J.C. et Gerono, A. Modification exp6rimentale de la phase terminale de la V.C.N. Rev. EEG Neurophysiol., 1975, 5: 10--14. Dongier, M. and Bostem, F. Tentative application in psychiatry of the contingent negative variation. Electroenceph. clin. Neurophysiol., 1967, 23: 282. Dongier, M., Timsit-Berthier, M., Koninkx, N. and Delaunoy, J. Compared clinical significance of CNV and other slow potential changes in psychiatry. In: W.C. McCallum and J.R. K n o t t (Eds.), Event-related Slow Potentials of the Brain; their Relations to Behavior. Elsevier, Amsterdam, 1973: 321--326. Floris, V., Morocutti, C., Amabile, G. e Bernardi, G. Recenti Acquisizioni Elettrofisiologiche in Cam-

285 po Psichiatrico. Problemi di Neurologia e Psichiatria. I1 Pensiero Scientifico, Rome, 1968. Gauthier, P. et Gottesmann, C1. Etude de la variation contingente n6gative et de l'onde post-imp6rative en pr6sence d'interf6rences. Electroenceph. clin. Neurophysiol., 1976, 40 : 143--152. Hablitz, J.J. and Borda, R.P. The effects of Dalmane (flurazepam hydrochloride) on the contingent negative variation. In: W.C. McCallum and J.R. Knott (Eds.), Event-related Slow Potentials of the Brain: their Relationship to Behavior. Elsevier, Amsterdam, 1973 : 329--335. Irwin, D.A., Knott, J.R., McAdam, D.W. and Rebert, C.S. Motivational determinants of the CNV. Electroenceph, clin. Neurophysiol., 1966, 21: 538-543. Knott, J.R. and Irwin, D.A. Anxiety, stress and the CNV. Electroenceph. clin. Neurophysiol., 1967, 31: 131--137. Low, M.D. and McSherry, J.W. Further observations of psychological factors involved in CNV genesis. Electroenceph. clin. Neurophysiol., 1968, 25: 203--207. Low, M.D., Coats, A.C., Retting, G.M. and McSherry, J.W. Anxiety, attentiveness-alertness: a phenomenological study of the CNV. Neuropsychologia (Bed.), 1967, 5: 379--384. McCallum, W.C. and Abraham, P. The contingent negative variation in psychosis. In: W.C. McCallum and J.R. Knott (Eds.), Event-related Slow Potentials of the Brain: their Relations to Behavior. Elsevier, Amsterdam, 1973 : 317--320. McCallum, W.C. and Cummins, B. The effects of brain lesions on the contingent negative variation in neurosurgical patients. Electroenceph. clin. Neurophysiol., 1973, 35: 449--456. McCallum, W.C. and Walter, W.G. The effects of attention and distraction on the contingent negative variation in normal and neurotic subjects. Electroenceph. clin. Neurophysiol., 1968, 35: 319--329. Tecce, J.J. Contingent negative variation (CNV) and psychological processes in man. Psychol. Bull., 1972, 77: 73--108. Tecce, J.J. and Cole, J.O. Amphetamine effects in man: paradoxical drowsiness and lowered electrical brain activity. Science, 1974, 185: 451--453. Timsit-Berthier, M., Delaunoy, J. and Koninkx, N. Slow potentials change in psychiatry. Contingent negative variation. Electroenceph. clin. Neurophysiol., 1973, 35: 355--361. Walter, W.G. Slow potential changes in the human brain associated with expectancy, decision and intention. Electroenceph. clin. Neurophysiol., 1967, 26: 123--129. Wechsler, D. The Measurement of Adult Intelligence, 3rd ed. Williams and Wilkins, Baltimore, Md., 1944.

A CNV study in a group of patients with traumatic head injuries.

Electroencephalography and Clinical Neurophysiology, 1 9 7 8 , 4 5 : 2 8 1 - - 2 8 5 © E l s e v i e r / N o r t h - H o l l a n d Scientific P u b l...
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