POSTURAL REFLEXES IN PATIENTS WITH HIV-1 INFECTION

Objective: We studied whether medium latency (ML) and long latency (LL ) postural reflexes, which are abnormal in a number of neurological co nditions including basal ganglia disorders, provide an early marker of CNS involvement in HIV-positive patients. Methods: Leg reflexes were elicited in 9 neurologically normal HIV-positive patients and 10 healt hy controls who were standing upright, using toe-up forceplate rotatio ns of varying amplitude (4 degrees and 10 degrees) and predictability (serial and random). Results: For predictable amplitude perturbations, posturally destabilizing ML and stabilizing LL responses in HIV-serop ositives did not differ from controls. However, for unpredictable ampl itude perturbations, HIV-positive patients inappropriately manifested a mid-size default LL response, in contrast to healthy subjects who sh owed a maximum size default response. Conclusions: These results sugge st that impaired modulation of LL reflex processing occurs in early st ages of HIV infection, prior to the onset of clinical postural instabi lity, and this dysregulation may be influenced by cognitive factors. ( C) 1998 Elsevier Science Ireland Ltd. All rights reserved.