Pusher syndrome in stroke: Clinical, neuropsychological and neurophysiological investigation

Background. Pusher syndrome i.e. the tendency of patients to push towards the hemiplegic side, is quite commonly observed in neurorehabilitation units. Nevertheless little research has been carried out to clarify factors that contribute to create such clinical condition. We examined the influence of cognitive and neurophysiological impairment in producing the syndrome. Methods. Two groups of patients with (22 patients) and without (12 patients) pushing behaviour were considered. Functional Indipendence Measure (FIM), evaluation of pushing behaviour and a neurological examination was performed in all patients. Neuropsychologically 16 patients with pushing behaviour were assessed using Mini Mental State Examination (MMSE), tests for all type of neglect, and tests for hemispatial akinesia, endoevoked directional akinesia and motor impersistence. Tactile, visual and auditory extinction was considered too. Somatosensory evoked potentials (SSEP) latencies and amplitudes of posterior tibial nerve and sural nerve sensory action potential (SAP) latencies and amplitudes were measured in all patients. Results. TC examination pusher group showed more that one localization, cortical and subcortical lesions, with a prevalence of right hemisphere involvement. Personal neglect, motor impersistence, auditory and visual extinction appeared clearly correlated to pushing behaviour severity. Lack of statistical evidence regarding frequencies of pathological SSEP latencies of sound side in the two groups seem to rule out that sensitive afferences from the sound side form a peculiar clinical feature, although comparison between SSEP latencies of two hemisides within single groups (pusher, no-pusher) point out that in pusher group doesn't exist expressive difference between latencies of two hemisides because probable increasing of SSEP latency of sound side. Conclusions. In conclusion our findings seem to support the hypothesis that internal body representation deficits associated with attentional disorders (impersistence) and residual neglect impairment (visual and auditory extinction) play an important role in the severity of pushing behaviour