INDICE PARADOX : UN NUOVO PARAMETRO POSTUROGRAFICO ESPRESSIONE DEL COINVOLGIMENTO FUNZIONALE CEREBELLARE NEI PAZIENTI VERTIGINOSI
Abstract
ABSTRACT
Kohen–Ratz described in autistic children a particular behaviour of posturographic findings that he named “Paradox Effect” : to be more stable when standing on foam pads with eyes closed as compared to solid surface with eyes open. He correlated this “paradox” phenomenon to the involvement of cerebellar controls.
The aim of this paper is to investigate the incidence of Paradox Effect in a large dizzy population.
Normal values were calculated in 65 normals subjects (43 females and 22 males mean age 43,8 yy). NORMAL PARADOX INDEX ( P. I. ). It was calculated as 0.8 + SD 0.12 on the basis of mean surface values. It can be considered pathological when the index is more than 1.1 (mean value+ 3SD). Althoug PI could be calculated comparing every body sway referred parameter by means of every kind of postutographic equipment, only patients investigated through Tetrax Equipment. 1300 dizzy patients (856 females and 444 males mean age 64,7 yy) were included.
Abnormal P.I. was found in 183 cases ( 98 females and 85 males mean age 49,5 yy; 14 % ). 60 cases (33% ) presented dizziness after whiplash. In all cases MRI was performed. MRI showed cerebellar lesions in 3 cases in Traumatic group ( 5 %) and normal in the others. In no-traumatic group MRI showed cerebellar lesions in 37 (30 %) and Central Nervous System lesions, in general, in 73 (59.3 %)
Paradoxical behaviour can be easily investigated because it is based on comparison of body sway in two conditions usually performed during routine posturography: standing with eyes open on solid surface and with eyes closed on foam, and expressed by means of Paradox Index.
Thus, even if paradox effect is not frequent to be observe, it can be considered a specific sign suggesting a CNS, in general, and cerebellar, particularly, involvement.