Signes neurologiques mineurs dans la schizophrénie précoce

Abstract

Neurological soft signs (NSS) are subtle neurological abnormalities that cannot be linked to the achievement of a specific region of the central nervous system and which are not part of a particular neurological syndrome. These signs are observed in the case of diseases supporting the neurodevelopmental model such as schizophrenia in general and its early form defined notably by an age of onset of less than 18 years. Indeed, the NSS belong to a set of clinical, cognitive, electrophysiological and neuroanatomical markers reflecting neurodevelopmental brain abnormalities in patients with schizophrenia. The objectives of our study were to determine the prevalence, the scores, and the nature of neurological soft signs (NSS) in adolescent patients suffering from early onset schizophrenia diagnosis in comparison to healthy controls, and to explore the correlations between NSS and the demographic, clinical and therapeutic features of these patients. Twelve adolescents were recruited in the Child Psychiatry Department at the Razi Hospital (Tunisia), with the diagnosis of schizophrenia according to the DSM-IV supplemented by the Kiddie SAD PL. They were matched by age and educational level with twelve healthy controls without psychiatric family or personal history. The clinical status of the patients was assessed using the Positive and Negative Syndrome Scale (PANSS). Neurological soft signs (NSS) were rated with the Neurological Soft Signs Examination (NSSE) by Krebs et al. (2000) for the two groups. This scale is composed of 23 items exploring motor coordination, motor integrative function, sensory integration, involuntary movements and quality of lateralization. The mean age of our population was 14.7 years. The average age of onset of the disease was 12.2 years. The sex-ratio was 1.4. Educational level was 7.4 years. The PANSS mean total score was 74.3. The mean daily dose, in chlorpromazine equivalents, was 523.9 mg/day. Four patients received a strict monotherapy of antipsychotics, while the other patients were receiving an association of two neuroleptics. The prevalence of NSS was 100% (cut-off point=11) with a mean total score of 29.3±4.1. The highest score was for the motor coordination (10.1). As for the control group, the mean total score was 7±1.3. A highly significant difference was found between patients and controls for all sub-scores of NSS. Negative correlations were found in patients, between age and neurological soft signs total score (P=0.05; r=-0.57) and also with sensory integration score (P=0.04; r=-0.58). The NSS total score was also correlated with low educational level (P=0.03; r=-0.61). There was no correlation between neurological soft signs scores and PANSS scores or the daily dose of antipsychotics. The prevalence and NSS scores are high among young people with early onset schizophrenia diagnosis illustrating the existence of structural abnormalities of the brain, themselves consequences of early neurodevelopmental disturbances, which would support the neurodevelopmental hypothesis concerning this pathology.