Neurological Soft Signs and Brain Abnormalities in Schizophrenia: A Literature Review.

Bindu Rathod,Stacey E Heindl,Sadia Nosher,Devyani Mohan,Nupur Mishra,Zaid A Alrashid,Deepak M Basavanagowda,Arveen Kaur,Sehrish Fuad

doi:10.7759/cureus.11050

Abstract

Neurological soft signs (NSS) are subtle neurological impairments in sensory integration, motor coordination, balance, and sequencing of complex motor acts. The prevalence of NSS is well over 50% in schizophrenic patients compared to about 5% in healthy controls. About 30% of schizophrenia patients are resistant to treatment. The main reason for not finding better pharmaceutical agents is the inability to elicit the underlying neurophysiological and neuroanatomical basis of schizophrenia. The most common NSS can be divided into three domains: motor coordination, sequencing of complex motor acts, and sensory integration. Here, the neuroimaging correlates of the abovementioned NSS are reviewed. Most of the studies found a negative correlation of NSS subs cores motor coordination and complex motor tasks with the cerebellum, inferior frontal gyrus, and postcentral gyrus. There was a negative correlation between cortical thickness and NSS total scores in the left paracentral lobule, precuneus, middle frontal cortex, right inferior temporal cortex, left/right superior parietal cortex. Instead of considering NSS as a mere trait or state markers, its active inclusion in patient management is required to improve patients' quality of life. Future studies on larger cohorts, combining different imaging modalities are needed to elucidate how these factors might relate to each other and contribute to NSS.

Highlights

BackgroundNeurological soft signs (NSS) are defined as subtle neurological impairments in sensory integration, motor coordination, balance, and sequencing of complex motor acts [1]
There was a negative correlation between cortical thickness and NSS total scores in the left paracentral lobule, precuneus, middle frontal cortex, right inferior temporal cortex, left/right superior parietal cortex
The study detected negative correlations between higher NSS scores on the subscale "integrative functions" and cortical thickness in the right paracentral lobule, inferior parietal lobe, and precuneus. These findings suggest that cortical thickness may serve as a very sensitive metric and as a possible indicator of a distinct process in schizophrenia patients with NSS

Summary

Introduction

Neurological soft signs (NSS) are defined as subtle neurological impairments in sensory integration, motor coordination, balance, and sequencing of complex motor acts [1]. Compared with the healthy controls, the schizophrenic patients showed a decreased activation of both sensorimotor cortices and supplementary motor area (SMA) and a reversed lateralization effect This may be an indication that the sensorimotor cortex and SMA dysfunction may contribute to NSS. Optimized voxel-based morphometry (VBM) analysis showed that the MSS sub-score had a significant negative correlation with total and regional GM volumes (prefrontal, posterior cingulate, temporal cortices, putamen, and cerebellum) in schizophrenia patients but not in controls. A recent study showed a progressive cognitive decline in patients with chronic schizophrenia along with increases on the NSS subscales of "motor coordination" and "integrative functions." the study was limited by confounding factors of diabetes mellitus, metabolic syndrome, small sample size, and patients' inability to come for follow-up [28].

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Scheffer RE