THESES
THE PREDICTIVE VALUE OF THE TAP-TEST IN NORMAL PRESSURE HYDROCEPHALUS (ABSTRACT)* * O valor preditivo da punção liquórica ("tap-test") na hidrocefalia de pressão normal. Tese de Livre Docência, Faculdade de Ciências Médicas da Universidade Estadual de Campinas (UNICAMP). . THESIS. CAMPINAS, 2000.
BENITO PEREIRA DAMASCENO ** ** Address: Rua Maria Monteiro 1710 / 24, 13025-152 Campinas SP, Brasil.
Normal pressure hydrocephalus (NPH) represents 1 to 12% of dementias. It is characterized by gait disturbance, progressive mental deterioration and urinary incontinence, associated with enlargement of the ventricular system and normal cerebrospinal fluid (CSF) pressure. In typical cases, gait disturbance is the first and most salient sign, followed by forgetfulness or mild dementia, psychomotor retardation, apathy and, later on, urinary urgency or incontinence. These cases present minor diagnostic difficulties and they are the most likely to improve after shunting. Differential diagnostic problems may, however, arise in some patients with atypical or incomplete clinical manifestations, as well as in patients with "subcortical" dementia such as Parkinson's disease, progressive supranuclear palsy and Binswanger's disease, which is the most common cause of the syndrome. In these cases, the results of computerized tomography (CT), magnetic resonance imaging (MRI) or radionuclide cisternography (RC) can be inconclusive or insufficient to establish a correct diagnosis and particularly to predict which patients will improve after shunting, hence the need to develop better methods for selecting patients to surgery.
Therefore, we introduced into our Department of Neurology (UNICAMP's Medical School) the CSF tap-test (TT), which consists of measurements of gait pattern and psychometric functions before and after the removal of 50 to 100 mL CSF by lumbar puncture (LP).
The first version of the test (TT-I; used from 1988 to 1995) covered gait (to walk 18 m as quickly as possible), visuo-motor speed (to move 60 cylinders from one place to another as fast as possible), visuo-constructive skills (to reproduce designs with matches or Kohs cubes), tactile memory (4 objects), visual memory (4 figures) and verbal memory (learning a list of 10 unrelated words).
The second version of TT (TT-II; used since 1996) tested gait (as in TT-I), verbal memory (learning 10 words), and postural reactions. Katz index was employed to evaluate activities of daily life. Neurological and neuropsychological investigation included: neurologic examination and careful history, CT (or MRI), RC, relevant blood and CSF tests. Mini-Mental State Examination (Folstein et al., 1975), Luria's Neuropsychological Investigation (Christensen, 1979), Global Deterioration Scale (Reisberg et al., 1982), CAMDEX (Roth et al., 1988), ICD-10 (WHO, 1992), and NINCDS-ADRDA criteria for "probable" or "possible" Alzheimer's disease (McKahnn et al., 1984).
Sixty one patients with gait disturbance, mental deterioration and ventriculomegaly were studied. Thirthy one of them had NPH and underwent ventriculo-peritoneal shunt surgery, with subsequent improvement in 24 (77.4%) of them. There were 3 false-positive and 2 false-negative cases. Nine patients (29%) had postsurgical complications, mainly subdural hematoma.
There was good correlation between the results of TT and surgery (phi coefficient = 0.51, p < 0.01), particularly with the second version of TT and gait test (r = 1, p < 0.001).
Short history, gait disturbance preceding mental deterioration, high cognitive scores, dilatation of temporal horns, and disappearance (or reduction) of cortical sulci on CT were associated with good outcome after shunting. On the other hand, in contrast to several other studies, we could not confirm periventricular hypodensity or knowing of the cause as prognostic favorable factors.
The additional predictive values of TT and RC were greater than that of combined clinical and neuroimaging data in 24% and 12% of operated cases, respectively.
Our findings concur with those of other authors on the high diagnostic and predictive value of TT, particularly in situations where the clinical and neuroimaging data are inconclusive and do not allow to take the decision to operate or not.
Publication Dates
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Publication in this collection
01 Dec 2000 -
Date of issue
Dec 2000
