THE PREDICTIVE VALUE OF CEREBROSPINAL FLUID TAP-TEST
IN NORMAL PRESSURE HYDROCEPHALUS
BENITO P. DAMASCENO*. EDMUR F. CARELLI**, DONIZETI C. HONORATO**, JOSE J. FACURE**
ABSTRACT - Eighteen patients (mean age of 66.5 years) with normal pressure hydrocephalus (NPH) underwent a ventriculo-peritoneal shunt surgery. Prior to operation a cerebrospinal fluid tap-test (CSF-TT) was performed with measurements of gait pattern and psychometric functions (memory, visuo-motor speed and visuo-constructive skills) before and after the removal of 50 ml C S F b y lumbar puncture (LP). Fifteen patients improved and 3 were unchanged after surgery. Short duration of disease, gait disturbance preceding mental deterioration, wide temporal horns and small sulci on CT-scan were associated with good outcome after shunting. There was a good correlation between the
results of CSF-TT and shunt surgery (X2
= 4,11 ,phi = 0.48, p < 0.05), with gait test showing highest correlation (r = 0.99, p = 0.01). In conclusion, this version of CSF-TT proved to be an effective test to predict improvement after shunting in patients with NPH.
KEY W O R D S : normal pressure hydrocephalus, lumbar puncture, shunt surgery.
Valor preditivo da punção liquórica ("tap test") na hidrocefalia de pressão normal
R E S U M O - Este estudo visa melhorar o valor diagnóstico e preditivo da punção liquórica ("tap test", TT) na hidrocefalia de pressão normal (HPN), particularmente nos casos em que os dados clinicos e de neuroimagem são inconclusivos e não permitem uma decisão cirúrgica segura. Dezoito pacientes (média de idade = 66.5 anos) com HPN foram submetidos a derivação ("shunt") ventriculo-peritoneal. O TT era realizado antes da cirurgia, consistindo na análise quantitativa da marcha e funções cognitivas (memória, rapidez perceptivo-motora e habilidade vísuo-construtiva) antes e depois da retirada de 50 ml de liquor via punção lombar. Quinze pacientes melhoraram e 3 permaneceram inalterados após a cirurgia. Curta duração da doença, distúrbio da marcha precedendo a deterioração mental, dilatação dos cornos temporais e apagamento (ou redução) dos sulcos corticais na tomografia computadorizada cerebral estavam associados a bons resultados pós-operatórios. Houve boa correlação entre os resultados do TT e os do "shunt" (X2
= 4.11, phi = 0.48, p < 0.05), principalmente no teste da marcha (r = 0.99, p = 0.01). Esta versão do TT liquórico mostrou-se efetiva na prediçâo da melhora pós-operatória em pacientes com HPN.
PALAVRAS-CHAVE: hidrocefalia de pressão normal, punção lombar, cirurgia de "shunt".
N o r m a l p r e s s u r e h y d r o c e p h a l u s ( N P H ) is c h a r a c t e r i z e d b y g a i t d i s t u r b a n c e , p r o g r e s s i v e
m e n t a l d e t e r i o r a t i o n a n d u r i n a r y i n c o n t i n e n c e a s s o c i a t e d w i t h e n l a r g e m e n t o f t h e v e n t r i c u l a r s y s t e m
a n d n o r m a l c e r e b r o s p i n a l fluid ( C S F ) p r e s s u r e . In t y p i c a l c a s e s , gait d i s t u r b a n c e is t h e first and
m o s t s a l i e n t s i g n , f o l l o w e d by f o r g e t f u l l n e s s o r m i l d d e m e n t i a , p s y c h o m o t o r r e t a r d a t i o n , a p a t h y
( w i t h p a r k i n s o n i a n o r d e p r e s s i v e a p p e a r a n c e ) a n d , l a t e r o n , u r i n a r y u r g e n c y o r i n c o n t i n e n c e . T h e s e
c a s e s p r e s e n t m i n o r d i a g n o s t i c difficulties a n d t h e y a r e the m o s t l i k e l y to i m p r o v e after s h u n t i n g " "1 1
.
Differential d i a g n o s t i c p r o b l e m s m a y , h o w e v e r , a r i s e in s o m e p a t i e n t s w i t h a t y p i c a l o r i n c o m p l e t e
Unidade de Neuropsicologia e Neurolinguistica* e Disciplina de Neurocirurgia**, Departamento de Neurologia, Faculdade de Ciências Médicas (FCM), Universidade Estadual de Campinas (UNICAMP). Aceite: 5-dezembro-1997.
clinical m a n i f e s t a t i o n s , as well as in p a t i e n t s with " s u b c o r t i c a l " d e m e n t i a ( s u b c o r t i c a l a r t e r i o s c l e r o t i c
e n c e p h a l o p a t h y o r B i n s w a n g e r ' s d i s e a s e , p r o g r e s s i v e s u p r a n u c l e a r p a l s y , P a r k i n s o n ' s d i s e a s e ) ,
w h i c h c a n m i m i c t h e c l i n i c a l p i c t u r e of N P H . S u b c o r t i c a l a r t e r i o s c l e r o t i c e n c e p h a l o p a t h y i s , in
fact, m u c h m o r e c o m m o n t h a n N P H a n d s h o u l d b e i n c l u d e d in t h e differential d i a g n o s i s as t h e
m o s t p r o b a b l e c a u s e of t h e " c l a s s i c a l " t r i a di s
. T h e r e s u l t s o f c o m p u t e r i z e d t o m o g r a p h y ( C T ) ,
m a g n e t i c r e s o n a n c e i m a g i n g ( M R I ) o r r a d i o n u c l i d e c i s t e r n o g r a p h y ( R C ) c a n b e i n c o n c l u s i v e a n d
insufficient to e s t a b l i s h a c o r r e c t d i a g n o s i s a n d p a r t i c u l a r l y to p r e d i c t w h i c h p a t i e n t s will i m p r o v e
after s h u n t s u r g e r y . A " p o s i t i v e " R C ( w i t h v e n t r i c u l a r reflux a n d c o n v e x i t y b l o c k ) is n o t s p e c i f i c
for N P H a n d c a n b e s e e n in o t h e r d e m e n t i a d i s o r d e r s a n d e v e n in h e a l t h y s u b j e c t s2
. R C ' s p r e d i c t i v e
v a l u e h a s b e e n r e p e a t e d l y q u e s t i o n e d , s o t h a t V a n n e s t e et a l .2 ( )
s u g g e s t e d it s h o u l d n o l o n g e r b e
p e r f o r m e d , as it will n o t r e d u c e t h e d i a g n o s t i c u n c e r t a i n t y r e m a i n i n g after c l i n i c a l a n d C T e v a l u a t i o n .
E v e n M R I ( w i t h C S F v o i d i n g s i g n in t h e a q u e d u c t ) h a s b e e n c r i t i c i z e d for its d o u b t f u l a d d i t i o n a l
p r e d i c t i v e v a l u e , b e s i d e s its l i m i t e d a v a i l a b i l i t y a n d h i g h c o s t s1 9
. All t h e s e l i m i t a t i o n s h a v e s t i m u l a t e d
the s e a r c h for m o r e a c c u r a t e m e t h o d s a n d c r i t e r i a for s e l e c t i o n of p a t i e n t s for s h u n t s u r g e r y , w h i c h
can b e n e f i t 2 5 - 8 0 % of t h e s e p a t i e n t s b u t h a s c o m p l i c a t i o n r a t e s ( 3 5 - 5 2 % ) t h a t d i s s u a d e u s f r o m
s h u n t i n g e v e r y c a s e w i t h s u s p i c i o n of N P H1 1 1 3
. T h u s , A d a m s et a l .1
a n d F i s h e r7
o r i g i n a l l y d e s c r i b e d
the beneficial ( t h o u g h t r a n s i e n t ) effect of C S F r e m o v a l in p a t i e n t s w i t h h y d r o c e p h a l i c d e m e n t i a , as
well as the i m p r o v e m e n t of t h e s e p a t i e n t s after s h u n t s u r g e r y . T h i s m e t h o d w a s later i m p r o v e d b y
W i k k e l s o et a l .2 3
-4
by i n t r o d u c i n g t h e q u a n t i t a t i v e t e s t i n g of g a i t a n d c o g n i t i v e f u n c t i o n s b e f o r e a n d
after t h e d r a i n a g e of 4 0 - 5 0 ml l u m b a r C S F ( C S F t a p test, h e n c e f o r t h c a l l e d T T ) . W i k k e l s o et al.
f o u n d t h a t this test c a n p r e d i c t n o t o n l y t h e o u t c o m e of s u r g e r y b u t a l s o t h e d e g r e e of i m p r o v e m e n t .
Lately, h o w e v e r , this test has b e e n c r i t i c i z e d for its h i g h r a t e of false n e g a t i v e s , w h i c h h a s led s o m e
a u t h o r s4
" to i n t r o d u c e t h e 5 d a y s c o n t i n u o u s e x t e r n a l l u m b a r d r a i n a g e in an a t t e m p t to i m p r o v e t h e
t e s t ' s p r e d i c t i v e v a l u e .
T h e a i m of this s t u d y w a s to e v a l u a t e t h e p r e d i c t i v e v a l u e of a m o d i f i e d v e r s i o n of W i k k c l s o ' s
T T , with a d a p t a t i o n s s u i t e d to test e v e n i l l i t e r a t e s u b j e c t s .
MATERIAL AND METHODS
Thirty-one patients with cognitive deterioration and enlarged ventricles were admitted to the Department of Neurology on suspicion of NPH. Eighteen of them (12 men and 6 women) were finally diagnosed as NPH and underwent a ventriculo-peritoneal shunt surgery with a medium-pressure valve. The remaining 13 patients (11 men and 2 women) had other types of dementia (Table) and were taken in this study as disease controls. NPH patients had mean age of 66.5 years (SD 9.6), average educational level of 2.1 years (SD 1.6), median duration of illness of 12 months, mean ventricular (frontal horns) index of 0.41 (SD 0.06; range 0.34 - 0.59) and mean score on Mini-Mental State Examination (MMSE) of 11.5 points (SD 4.3).
Every patient underwent the following evaluations: neurologic examination and careful history (obtained from both the patient and a relative); CT; electroencephalography; C S F analysis and relevant haematological, biochemical, bacteriological and immunological tests (for syphilis, toxoplasmosis and cysticercosis); MMSE'' (adapted by Beitolucci et al.)'; ChristcnscnV comprehensive test-battery ("Luria's Neuropsychological Investigation"); and,
at last, TT. We used ICD-10 criteria2 2
for the diagnosis of dementia, which was graded by means of Reisberg's1 5
Global Deterioration Scale. NINCDS-ADRDA criteria1 4
were used for the diagnosis of probable and possible Alzheimer's disease.
The diagnosis of NPH was based on the following criteria: 1) a history of gait disturbance, progressive mental deterioration, and urinary urgency or incontinence; 2) hydrocephalus, defined as Evans' ratio (the ratio between the maximal width of the frontal horns and the internal diameter of the skull at the same level) above 0.30 on CT; 3) a mean C S F pressure below 18 cm of water.
(with psychometric tests and gait analysis) was performed at 3 and 6 months, at 1 year, and thereafter every year. CT was regularly repeated at the 6th month follow-up. If the patient did not improve, we examined the shunt function by percutaneously testing the proximal and distal patency of the shunt (and the valve function), as well as by analysing changes in ventricular size on CT scan. TT test-battery took about 30 minutes to be administered and comprised following subtests:
A. Gait examination. The examiner counted the number of steps and the time spent by the patient for walking 18 in as quickly as possible. The mean value of four attempts was the patient's score.
B. Test ofvisuo-motor speed (Cylinders test)"3
. The test consists of 2 wooden plates with 60 holes in each
plate. In one plate, the holes are filled with easily graspable cylinders. The task was to move (with the dominant hand) the cylinders from one plate to another as fast as possible. The time needed to place all cylinders was measured, taking the average of three attempts.
C. Visuo-constructive skills. (1) To copy (with nine matches) two pentagons bound by one of their sides (score 1 if this was correctly copied). (2) Kohs test: to reproduce stimulus designs with four multicolored cubes. The
four test items of Figure 7-11 of Strub & Black1 7
were used. A score of 1 was given for each correctly reproduced design. Rotations (either right-left or near-far) as well as figure-ground (color) reversals were scored as incorrect. The maximum score of test C was 5 points.
D. Memory. (1) Tactile-verbal memory: The subject had to recall orally or by tactile multiple choice four objects recognized by touch (and eventually named) three minutes earlier (button and match in the right hand; coin and nail in the left hand). One point was given for each correctly recalled object. If the subject was unable to recognize these objects (due to paresis or astereognosis), he/she was allowed to see (and name) them. (2) Visual memory: The subject was shown a relatively nonverbalizable drawing for 10 seconds and asked to choose the correct one from
among four others after a three-minutes ocupied pause [test items of Figure 1 of Rossl f
' were used]. Four different stimulus items were tested (1 point for each item correctly recognized). (3) Verbal learning: the subject was given ten trials to learn a list of 10 unrelated words presented orally by the examiner (water, flower, cat, key, stone, cross, street, cake, hand, wind). His/her score was the mean of summed total recall across the ten acquisition trials. Maximal score of test D was 18 points. At the post-LP psychometric testing, the stimulus items of these memory tests were substituted for other items to avoid learning effect: in test D-1 were given a key and a rubber in the right hand and a pencil and a teaspoon in the left hand; and in test D-3 were presented following words: house, ox, bread, night, bell, light, bridge, table, foot, rain.
Improvement (or deterioration) in tests A and B was defined as an increase (or decrease) of 5%, and in tests C and D as an increase (or decrease) of 20%. TT was considered as positive if the patient's performance had improved in at least one of the subtests. In the statistical analysis we used chi-square (or Fisher's exact test) for comparison of proportion; and Student's t test for comparison of means between NPH patients and controls. The differences in variables before and after shunt operation [and before and after LP (TT)] were tested by Student's t test for paired data. Pearson product-moment correlation coefficient was used to determine relationships between results of TT subtests after LP and after shunting. The significance level was set at alpha = 0.05.
RESULTS
N P H p a t i e n t s w e r e s i m i l a r to c o n t r o l s as r e g a r d s m e a n a g e (t = 1.81, df = 2 9 , p > 0 . 0 7 ) ,
e d u c a t i o n a l level (t = 1.96, df = 2 9 , p > 0 . 0 5 ) , v e n t r i c u l a r i n d e x (t = 0 . 8 4 , df" = 2 9 , p = 0 . 4 1 ) ,
M M S E s c o r e s (/ = 0 . 2 3 , df = 2 9 , p = 0 . 2 ) , f r e q u e n c y of p e r i v e n t r i c u l a r h y p o d e n s i t y ( X2
= 3 . 3 2 , df
= 2, p = 0 . 1 9 ) , c o r t i c a l a t r o p h y ( X2
= 2 . 8 2 , df = 2 , p = 0 . 2 4 ) a n d d i l a t a t i o n o f t e m p o r a l h o r n s ( X2
=
0 . 1 9 , df = 2 , p = 0 . 9 ) . P r o p o r t i o n of i m p r o v e d p a t i e n t s a n d d e g r e e o f i m p r o v e m e n t at T T w e r e
h i g h e r in t h e N P H g r o u p ( X2
= 9 . 4 1 , df = 2 , p < 0 . 0 1 ) . T h i s g r o u p a l s o h a d g r e a t e r p r o p o r t i o n of
w o m e n ( t h o u g h p = 0 . 2 4 ) . A m o n g h y d r o c e p h a l i c p a t i e n t s , 5 w e r e i l l i t e r a t e a n d 13 h a d at m o s t 4
y e a r s e l e m e n t a r y s c h o o l . If w e c o n s i d e r M M S E c u t - o f f p o i n t s of 13 for i l l i t e r a t e , 18 for s u b j e c t s
w i t h 1 to 8 y e a r s e d u c a t i o n , a n d 2 6 for s u b j e c t s w i t h m o r e t h a n 8 y e a r s e d u c a t i o n (after B e r t o l u c c i
et a l . ) \ w e s e e t h a t all b u t t w o (illiterate) h y d r o c e p h a l i c p a t i e n t s a n d all but o n e (illiterate) c o n t r o l s
s c o r e d b e l o w t h e s e p o i n t s a n d s h o w e d v a r i e d d e g r e e s of c o g n i t i v e deficit.
In 12 c a s e s t h e c a u s e o f N P H w a s u n k n o w n , w h i l e in t h e o t h e r s it w a s a s s o c i a t e d w i t h
s u b a r a c h n o i d h e m o r r h a g e ( 2 p a t i e n t s ) , h e a d t r a u m a , l a c u n a r i n f a r c t s , c y s t i c e r c o t i c c a l c i f i c a t i o n s
a n d r e l a p s i n g ( b i p a r i e t a l ) falx m e n i n g i o m a (1 e a c h ) . E i g h t N P H p a t i e n t s h a d p r e v i o u s l y b e e n
c h i l d h o o d e p i l e p s y , r h e u m a t o i d a r t h r i t i s a n d h y p e r t h y r o i d i s m (1 e a c h ) . T h e m o s t c o m m o n
n e u r o l o g i c a l f i n d i n g s w e r e h y p e r r e f l e x i a ( 1 2 p a t i e n t s ) , s p a s t i c p a r a p a r e s i s ( 6 ) , a n d p r i m i t i v e
r e f l e x e s a s s n o u t i n g ( 6 ) , p a l m o m e n t a l ( 5 ) , B a b i n s k i s i g n ( 4 ) , s u c k i n g (3) a n d g r a s p i n g ( 2 ) . G a i t
d i s t u r b a n c e w a s s e e n in all p a t i e n t s , a n d u r i n a r y u r g e n c y o r i n c o n t i n e n c e in 15 ( 8 3 % ) . M e n t a l
d e t e r i o r a t i o n w a s d e t e c t e d in 17 N P H p a t i e n t s ( 9 4 . 5 % ) , 15 ( 8 3 % ) of w h o m h a d d e m e n t i a ( w h i c h
w a s m i l d in 6, m i l d t o m o d e r a t e in 2 , m o d e r a t e in 3 , a n d m o d e r a t e t o s e v e r e in 4 ) , a n d t w o o t h e r s
h a d a m n e s i a . T h e m o s t f r e q u e n t i n i t i a l s y m p t o m s of N P H o c c u r r e d c o n c o m i t a n t l y in g a i t ,
m i c t u r i t i o n a n d m e m o r y (5 p a t i e n t s ) , in g a i t a n d m i c t u r i t i o n ( 5 ) , in g a i t a n d m e m o r y ( 2 ) , o n l y in
g a i t ( 3 ) , a n d o n l y in m e m o r y ( 3 ) .
M o s t c o n t r o l s ( 6 1 . 6 % ) h a d v a s c u l a r d e m e n t i a . W e f o u n d in t h i s g r o u p a h i s t o r y o f
h y p e r t e n s i o n (5 p a t i e n t s , t w o of w h i c h h a d p a s t m y o c a r d i a l i n f a r c t ) , a l c o h o l i s m ( 3 ) , d i a b e t e s
m e l l i t u s ( 1 ) , h y p o t h y r o i d i s m (1) a n d h e m o p h i l i a A ( 1 ) .
F i f t e e n p a t i e n t s ( 8 3 % ) i m p r o v e d after s h u n t s u r g e r y w h i l e 3 ( 1 7 % ) d e t e r i o r a t e d o r r e m a i n e d
u n c h a n g e d . I m p r o v e m e n t w a s fair t o g o o d in 10 a n d e x c e l l e n t in 5 p a t i e n t s (of w h o m 3 s h o w e d
n o r m a l i z a t i o n o f g a i t a n d c o g n i t i v e f u n c t i o n s ) . S h u n t c o m p l i c a t i o n ( o b s t r u c t i o n ) w a s s e e n in o n l y
o n e p a t i e n t ( C a s e 3 ) , w h i c h w a s r e o p e r a t e d s u c c e s s f u l l y . T h i r t e e n s h u n t r e s p o n s i v e s u b j e c t s h a d
i m p r o v e d at T T , w h i c h s h o w e d o n l y 1 f a l s e - p o s i t i v e a n d 2 f a l s e - n e g a t i v e r e s u l t s . T h u s , t h e r e w a s
a g o o d c o r r e l a t i o n b e t w e e n t h e r e s u l t s of T T a n d s h u n t s u r g e r y ( X2
= 4 . 1 1 , d f = 1, phi c o e f f i c i e n t
= 0 . 4 8 , p < 0 . 0 5 ) . If t h e i m p r o v e m e n t after s h u n t i n g is t a k e n a s t h e g o l d s t a n d a r d for t h e d i a g n o s i s
of N P H , t h e n t h e p o s i t i v e p r e d i c t i v e v a l u e o f o u r T T w a s 9 3 % , a n d its n e g a t i v e p r e d i c t i v e v a l u e
5 0 % . T T s e n s i t i v i t y w a s 8 7 % a n d its s p e c i f i c i t y 6 7 % .
T T s u b t e s t w i t h h i g h e s t s e n s i t i v i t y w a s t h a t of m e m o r y ( 8 0 % ) , w h i c h a l s o h a d h i g h p o s i t i v e
p r e d i c t i v e v a l u e ( 9 2 % ) [ b u t n e g a t i v e p r e d i c t i v e v a l u e o f 4 0 % ] . T h e s y m p t o m s m o s t f r e q u e n t l y
i m p r o v i n g after T T a n d s h u n t s u r g e r y w e r e a m n e s i a a n d g a i t d i s t u r b a n c e , f o l l o w e d b y v i s u o
-c o n s t r u -c t i v e d i s a b i l i t y , p s y -c h o m o t o r s l o w i n g , u r i n a r y u r g e n -c y o r i n -c o n t i n e n -c e , a n d m e n t a l
c o n f u s i o n o r d e l i r i u m . Yet, w h e n a n a l y s i n g o n l y t h e p a t i e n t s w i t h b e s t i m p r o v e m e n t after s h u n t i n g
( p a t i e n t s 3 , 4 , 6, 14 a n d 16), w e f o u n d a s i g n i f i c a n t c o r r e l a t i o n b e t w e e n t h e r e s u l t s of t h e gait
t e s t after T T a n d after s h u n t i n g ( r = 0 . 9 9 , p = 0 . 0 1 ) . H o w e v e r , t h i s c o r r e l a t i o n w a s n o t s i g n i f i c a n t
for t h e o t h e r s u b t e s t s (test B , r = 0 . 5 2 , p > 0 . 0 5 ; t e s t C , r = 0 ; test D , A - 0 . 6 6 , p > 0 . 0 5 ) . T h u s , g a i t
s u b t e s t w a s t h e b e s t p r e d i c t o r of s h u n t r e s u l t s .
T h e s e a r c h for o t h e r v a r i a b l e s t h a t c o u l d b e r e l a t e d t o s u r g i c a l o u t c o m e ( u s i n g S t u d e n t ' s t
t e s t a n d t h e F i s h e r e x a c t t e s t ) y i e l d e d f o l l o w i n g f i n d i n g s : ( 1 ) t h e r e w a s a t e n d e n c y t o l e s s
i m p r o v e m e n t , t h e l o n g e r t h e d u r a t i o n o f N P H , e v e n t h o u g h t h e d i f f e r e n c e s b e t w e e n t h e m e a n
d u r a t i o n s in 5 p a t i e n t s w i t h e x c e l l e n t i m p r o v e m e n t ( 1 3 . 8 y e a r s ; S D = 1 3 . 0 ) , in 10 p a t i e n t s w i t h
fair t o g o o d i m p r o v e m e n t ( 3 5 . 1 y e a r s ; S D = 5 6 . 1 ) , a n d in 3 p a t i e n t s w i t h n o i m p r o v e m e n t ( 4 4 . 0
y e a r s ; S D = 4 5 . 4 ) w e r e n o t s t a t i s t i c a l l y s i g n i f i c a n t ( 0 . 1 9 < p < 0 . 4 4 ) ; (2) i m p r o v e d p a t i e n t s t e n d e d
t o h a v e m o r e d i l a t a t i o n of t e m p o r a l h o r n s a n d l e s s c o r t i c a l a t r o p h y o n C T s c a n ( t h o u g h p = 0 . 1 0
a n d p = 0 . 2 8 , r e s p e c t i v e l y ) ; (3) u n i m p r o v e d p a t i e n t s h a d l o w e r s c o r e s o n M M S E (t = 2 . 3 9 , df =
16, p < 0 . 0 3 ) ; a n d ( 4 ) t h e r e w a s n o i n f l u e n c e of a g e , s e x o r e d u c a t i o n a l l e v e l o n s u r g i c a l o u t c o m e
a n d T T r e s u l t s .
DISCUSSION
It is w i d e l y a s s u m e d t h a t t h e s y m p t o m s a n d s i g n s of N P H a r e d u e t o a r e d u c t i o n of r e g i o n a l
c e r e b r a l b l o o d f l o w ( r C B F ) a n d m e t a b o l i s m , as a r e s u l t of a d i s t e n s i o n of t h i r d a n d lateral v e n t r i c l e s
( m o s t l y of frontal h o r n s ) r e l a t e d to an i m p a i r m e n t of C S F f l o w1
- -1
. T h e r e f o r e , t h e r a t i o n a l e w i t h
T T a n d s h u n t s u r g e r y h a s b e e n t h a t t h e y l o w e r t h e i n t r a c r a n i a l p r e s s u r e a n d t h e n e e d for C S F
r e s o r p t i o n , w i t h i n c r e a s e of r C B F ( m o s t l y in t h e a n t e r i o r p e r i v e n t r i c u l a r w h i t e m a t t e r ) . T h e
i m p r o v e m e n t , w h i c h , in o u r e x p e r i e n c e , l a s t e d f r o m 2 h to 4 8 h. O n e of o u r p a t i e n t s i m p r o v e d
after 2 4 h d e l a y . I m p r o v e m e n t w i t h l o n g e r d e l a y ( 4 8 h) a n d p e r s i s t i n g m a n y m o n t h s after a s i n g l e
2 0 - 3 0 ml C S F l a p h a s b e e n d e s c r i b e d7
. W e h a d n o c o m p l i c a t i o n s from t h e C S F d r a i n a g e p r o c e d u r e ,
and the p o s t s u r g i c a l c o m p l i c a t i o n r a t e at t h e 6th m o n t h a n d o n e y e a r f o l l o w - u p ( o n l y o n e c a s e w i t h
s h u n t d y s f u n c t i o n ) w a s l o w e r t h a n t h a t r e p o r t e d in t h e l i t e r a t u r e . S h u n t d y s f u n c t i o n m a y h a v e b e e n
u n d e t e c t e d , s i n c e t h e a s s e s s m e n t of s h u n t p a t e n c y o n l y w i t h d i g i t a l c o m p r e s s i o n is n o t e n t i r e l y
r e l i a b l e .
T h e s e l e c t i o n of T T s u b t e s t s t o o k i n t o a c c o u n t t h a t t h e y h a d to (1) b e s e n s i t i v e to N P H
clinical m a n i f e s t a t i o n s a n d m e a s u r e c o g n i t i v e f u n c t i o n s t h a t u s u a l l y i m p r o v e after L P a n d s h u n t i n g ;
(2) b e suited e v e n for i l l i t e r a t e s u b j e c t s , o n a c c o u n t of t h e h i g h i l l i t e r a c y r a t e of o u r p o p u l a t i o n of
p a t i e n t s ( 1 5 % ) ; (3) h a v e l o w c o s t a n d b e e a s y a n d r a p i d to a d m i n i s t e r by n e u r o l o g i s t s in a m b u l a t o r y
o u t p a t i e n t s . I n d e e d , all p a t i e n t s ( e x c e p t C a s e 17) c o u l d u n d e r s t a n d a n d p e r f o r m the t e s t s . C a s e 17
had s e v e r e d e m e n t i a a n d m u t i s m , w h i c h p r e c l u d e d h e r to p e r f o r m s u b t e s t D . 3 ( v e r b a l m e m o r y ) .
C a s e s 8, 9, 11 a n d 18 c o u l d n o t p e r f o r m w a l k i n g test b e c a u s e of m a r k e d s p a s t i c p a r a p a r e s i s . C a s e s
6 a n d 16, w h i c h c o u l d o n l y w a l k w i t h s i g n i f i c a n t s u p p o r t b e f o r e LP, w a l k e d i n d e p e n d e n t l y after it
( t h o u g h m i l d l y u n s t e a d y a n d with difficulty for t u r n i n g ) ; after s h u n t i n g , t h e y w a l k e d a l m o s t n o r m a l l y
but w i t h difficulty for t u r n i n g . F o r t h e s e t w o c a s e s , the d e g r e e of i m p r o v e m e n t in g a i t w a s c a l c u l a t e d
on t h e b a s i s of t h e t i m e ( a n d not of t h e n u m b e r of s t e p s ) s p e n t to w a l k 18 m.
T h e s e n s i t i v i t y a n d p o s i t i v e p r e d i c t i v e v a l u e s of o u r T T w e r e h i g h , b u t its r a t e of false
n e g a t i v e s ( 1 1 % ) calls for further i m p r o v e m e n t . T h e p a t i e n t s w h o d i d n o t i m p r o v e after T T a n d
s h u n t i n g p r o b a b l y h a d i r r e v e r s i b l e s t r u c t u r a l c h a n g e s , as m u c h as c a n b e inferred from t h e i r l o w
M M S E s c o r e s and m a r k e d d e m e n t i a . P a t i e n t 18 did n o t i m p r o v e p r o b a b l y b e c a u s e his m o d e r a t e
h y d r o c e p h a l i c d e m e n t i a w a s a s s o c i a t e d w i t h a s m a l l , s l o w l y g r o w i n g ( r e c u r r e n t ) falx m e n i n g i o m a ,
w h i c h could h a v e led to i m p a i r m e n t of C S F r e s o r p t i o n and p o s s i b l y a l s o to d y s f u n c t i o n of n e i g h b o r i n g
a s s o c i a t i v e parietal c o r t i c e s at both s i d e s . P a t i e n t 17, w i t h m u t i s m , s h o w e d i m p r o v e m e n t of s p e e c h
p r o d u c t i o n d u r i n g t h e first p o s t s u r g i c a l m o n t h ( s h e c o u l d g i v e a n s w e r s w i t h a p p r o p r i a t e w o r d s a n d
s h o r t s e n t e n c e s ) , b u t t h e n r e t u r n e d to h e r p r e v i o u s state.
In a g r e e m e n t w i t h t h e l i t e r a t u r e "1 3
'2 4
, w e h a v e f o u n d t h a t s h o r t h i s t o r y , g a i t d i s t u r b a n c e
p r e c e d i n g m e n t a l d e t e r i o r a t i o n , a s w e l l a s w i d e t e m p o r a l h o r n s a n d s m a l l s u l c i ( b u t n o t
p e r i v e n t r i c u l a r h y p o d e n s i t y ) o n C T scan w e r e a s s o c i a t e d with g o o d o u t c o m e after s h u n t i n g . L o n g
d u r a t i o n of d e m e n t i a ( a n d l o w M M S E s c o r e s ) t e n d e d to c o r r e l a t e w i t h p o o r o u t c o m e . O n t h e o t h e r
h a n d , in c o n t r a s t to s e v e r a l o t h e r s t u d i e s '3
-2 4
, w e c o u l d n o t c o n f i r m k n o w i n g of the c a u s e as a
p r o g n o s t i c f a v o u r a b l e factor. T h e d e g r e e of i m p r o v e m e n t in t h e g r o u p w i t h N P H of k n o w n c a u s e
w a s the s a m e as in t h e i d i o p a t h i c g r o u p ( 8 0 % ) . N e v e r t h e l e s s , this d o e s n o t a l l o w u s to q u e s t i o n t h e
p r o g n o s t i c r e l e v a n c e of e t i o l o g y , s i n c e in s o m e of o u r c a s e s t h e l o w e d u c a t i o n a l level a n d t h e lack
of m e d i c a l r e c o r d s of t h e i r p a s t h i s t o r y m a y h e l p to e x p l a i n t h e u n k n o w n e t i o l o g y .
O v e r a l l , o u r f i n d i n g s c o n f i r m t h o s e of W i k k e l s o et a l .2 4
p o i n t i n g to t h e h i g h d i a g n o s t i c a n d
p r e d i c t i v e v a l u e of T T , p a r t i c u l a r l y in s i t u a t i o n s w h e r e t h e c l i n i c a l a n d C T d a t a a r e i n c o n c l u s i v e
and d o not a l l o w to t a k e t h e d e c i s i o n to o p e r a t e or n o t . W e t h i n k t h a t T T s h o u l d b e further i m p r o v e d ,
e s p e c i a l l y b y d e v e l o p i n g m o r e s p e c i f i c tests for N P H d i s t u r b a n c e s of gait, p o s t u r e , m i c t u r i t i o n a n d
c o g n i t i o n , as well as b y i n c r e a s i n g t h e a m o u n t of C S F r e m o v e d , p r e f e r a b l y by m e a n s of o n e d a y ' s
r e p e a t e d o r c o n t i n u o u s C S F t a p ( w h i c h w o u l d r e d u c e t h e r i s k s , t r o u b l e s a n d c o s t s o f t h e five d a y ' s
c o n t i n u o u s e x t e r n a l d r a i n a g e p r o p o s e d b y o t h e r s ) .
Acknowledgements - This work was supported in part by a grant to the first author from FAEP (Fundo cie
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