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 conditions 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 healthy controls who were standing upright, using toe-up forceplate rotations of varying amplitude (4° and 10°) and predictability (serial and random).

Results: For predictable amplitude perturbations, posturally destabilizing ML and stabilizing LL responses in HIV-seropositives did not differ from controls. However, for unpredictable amplitude perturbations, HIV-positive patients inappropriately manifested a mid-size default LL response, in contrast to healthy subjects who showed a maximum size default response.

Conclusions: These results suggest that impaired modulation of LL reflex processing occurs in early stages of HIV infection, prior to the onset of clinical postural instability, and this dysregulation may be influenced by cognitive factors.