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Postural reflexes in patients with HIV-1 infection
D J Beckley1, B R Bloem, E M Martin
1Department of Neurology, School of Medicine, University of California, Davis, USA.
Electroencephalography and Clinical Neurophysiology
|December 16, 1998
Summary
HIV-positive individuals show altered long latency (LL) postural reflexes, particularly with unpredictable stimuli. This suggests early central nervous system (CNS) changes in HIV infection, potentially linked to cognitive function.
Area of Science:
- Neuroscience
- Immunology
- Human Physiology
Background:
- Postural reflexes, including medium latency (ML) and long latency (LL) responses, are crucial for maintaining balance.
- Abnormalities in ML and LL reflexes are observed in various neurological conditions, such as basal ganglia disorders.
- Central nervous system (CNS) involvement is a known complication of HIV infection.
Purpose of the Study:
- To investigate whether ML and LL postural reflexes can serve as early indicators of CNS involvement in HIV-positive patients.
- To determine if HIV-positive individuals exhibit distinct reflex patterns compared to healthy controls.
Main Methods:
- The study involved 9 neurologically normal HIV-positive patients and 10 healthy controls.
- Leg reflexes were measured using a forceplate that induced toe-up rotations of 4 and 10 degrees.
- Stimuli were presented in both predictable (serial) and unpredictable (random) sequences.
Main Results:
- No significant differences in ML or LL responses were found between HIV-positive patients and controls for predictable perturbations.
- During unpredictable perturbations, HIV-positive patients exhibited an inappropriate mid-size default LL response.
- Healthy controls demonstrated a maximum size default LL response to unpredictable perturbations.
Conclusions:
- Impaired modulation of LL reflex processing is suggested in early HIV infection stages.
- This reflex dysregulation may precede overt clinical signs of postural instability.
- Cognitive factors might influence the observed alterations in LL reflex processing in HIV-positive individuals.