Long-latency event-related potentials in asymptomatic human immunodeficiency virus type 1 infection

The nervous system in early HIV infection: a prospective study through 7 years

In this study 28 patients with early stage HIV infection (CD4 >280 x 10(6)/l) were subjected to yearly examinations of the nervous system up to 7 years in order to detect any deterioration. Clinical neurological as well as neuropsychological performance was evaluated. The patients also underwent yearly neurophysiological tests (digital EEG, visual evoked potentials, somatosensory evoked potentials, auditory evoked potentials P300 and electroneurography). Every other year, SPECT with (99m)Tc-D,L-hexamethylpropylene amine oxime and brain MRI were performed. Originally, 38 patients were included in the study but only the results of 28 patients who complied with three of more yearly check-ups are presented. The results of yearly investigations of cerebrospinal fluid (CSF) have been presented earlier [Eur J Neurol4 (1997) 1]. All the patients showed signs of HIV in the CSF. Yet, no major deterioration in the neurological, psychological performance, neurophysiological or neuroimaging examinations could be discerned.

Prevention of AIDS dementia by HAART does not depend on cerebrospinal fluid drug penetrance

The impact of the cerebrospinal fluid (CSF) penetrance properties of different highly active antiretroviral therapy (HAART) regimes on cognitive processing in AIDS dementia is still undetermined. We therefore designed a retrospective cross-sectional and prospective longitudinal analysis of event-related potentials in HIV-infected patients with different combinations of HAART or without antiretroviral treatment. A total of 353 consecutive patients without secondary CNS manifestation of HIV infection were enrolled in the cross-sectional study and 135 consecutive patients without secondary CNS manifestations of HIV infection were enrolled in the longitudinal study. HAART in different combinations (n = 306) or no antiretroviral treatment (n = 47) was given for at least 6 months in the retrospective cross-sectional study. HAART in different combinations (n = 110) or no antiretroviral treatment (n = 25) was given for 1 year in the prospective longitudinal study. We evaluated the latency and amplitude of the P3 component of visually evoked event-related potentials and mean choice reaction time as measures of cognitive processing. Patients receiving HAART had decreased P3 latencies as compared to those patients not receiving HAART but P3 latency and P3 amplitude were not correlated with the amount of CSF penetrance of the different HAART combinations in either statistical analysis. However, mean choice reaction time was significantly correlated with the amount of CSF penetrance. In HIV-infected patients, the CSF penetrance properties of HAART do not have any significant influence on cognitive processing as measured by event-related potentials.

Evidence of CNS impairment in HIV infection: clinical, neuropsychological, EEG, and MRI/MRS study

OBJECTIVES

To identify by clinical examination, EEG, MRI, and proton spectroscopy, and neuropsychological assessment the prevalence of signs of CNS involvement in patients infected with HIV, and to relate such findings to the evidence of immunosuppression.

METHODS

The design was a cross sectional analysis of a cohort of male patients with infected HIV with an AIDS defining diagnosis or low CD4 count (<350), and seropositive asymptomatic subjects, both groups being followed up in a longitudinal study. Control groups consisted of seronegative subjects from the same genitourinary medicine clinics.

RESULTS

This report sets out the cross sectional findings at the seventh visit in the longitudinal study. Patients with AIDS had more signs of neurological dysfunction, poorer performance on a neuropsychological test battery, were more likely to have an abnormal EEG, and to have abnormalities on MRI. They more often had cerebral atrophy, abnormal appearing white matter, and abnormal relaxometry and spectroscopy. There was little evidence of abnormality in seropositive people who had a CD4 count >350 compared with seronegative people from a similar background.

CONCLUSIONS

Detailed testing failed to disclose significant CNS impairment without immunosuppression in men infected with HIV. Findings from MRI and magnetic resonance spectroscopy (MRS) correlated with those of the neurological examination and neuropsychological assessment. A combination of such assessments offers a simple surrogate for studies of CNS involvement in HIV disease.

Impact of antiretroviral treatment on AIDS dementia: a longitudinal prospective event-related potential study

We investigated the impact of antiretroviral treatment on event-related potentials (ERP) as a possible marker of AIDS dementia. A total of 154 HIV-infected patients without central nervous system (CNS) neoplasm or opportunistic infection were examined and randomized to receive either zidovudine 500 mg/day or no antiretroviral treatment. The participants were prospectively examined by visually evoked ERP in a longitudinal design. Latencies and amplitudes of ERP were evaluated at the beginning of the study, after 1 year, and after 2 years. After 1 year, 98 patients could be analyzed, 47 of whom were taking zidovudine. In the treatment group, P3 latency was 419 +/- 55 msec at baseline and 424 +/- 52 msec at follow-up (not significant). In the patients without treatment, P3 latency was 437 +/- 42 msec at baseline and 462 +/- 53 msec at follow-up (p < .0001, Wilcoxon test). A significant inverse correlation existed between P3 latency and CD4 cell count in both groups. The increase of P3 latency in untreated patients and a stable P3 latency in treated patients could be confirmed in a subgroup analysis of 21 patients with a follow-up of three examinations in a 2-year period. Our data suggest that zidovudine has a positive impact on AIDS dementia as measured by ERP. This finding was observed in patients in different stages of HIV infection, thus suggesting that zidovudine is indicated in all stages of HIV infection to treat encephalopathy.

Progressive encephalopathy associated with CD4/CD8 inversion in adult FIV-infected cats

Experimental intravenous challenge of five adult cats with the feline immunodeficiency virus Maryland isolate (FIV-MD) was investigated for its ability to induce neurologic abnormalities associated with the onset of immunodeficiency. Five 8-month-old cats were inoculated with 1000 median tissue culture infective dose of FIV-MD isolate, with five age-matched cats serving as uninfected controls. All FIV-MD-infected cats tested positive for serum antiviral antibodies and plasma viral DNA as detected by polymerase chain reaction at 2, 4, 10, and 16 months postinfection (PI). At 10 and 16 months PI, there was a significant reduction in the CD4/CD8 lymphocyte ratio, with all cats having a CD4/CD8 ratio of 1 or less. Total protein electrophoretic analysis of cerebrospinal fluid demonstrated a significantly increased albumin quotient at 4 and 16 months PI, representing a disrupted blood-brain barrier (BBB). At 16 months PI, all cats demonstrated a preferential increase in frontal cortical slow-wave activity compared with control cats. Serial evaluation of brainstem auditory evoked potential recordings revealed a prolongation of the interpeak latencies times over the study time. At least one abnormality was found over time in visual and somatosensory evoked potential testing in three and four infected cats, respectively. Comparing lymphocyte subtype ratios with neurologic testing revealed that every FIV-MD-infected cat exhibited an abnormality in at least one neurologic functional test with a concurrent CD4/CD8 count ratio of 1 or less. Overall, this study demonstrated that FIV-MD infection in adult cats results in a delayed-onset, progressive encephalopathy that parallels the decline in the CD4/CD8 lymphocyte ratio. Compared with prior information from pediatric FIV-MD-infected cats, these results indicate that age of infection influences the onset and severity of disease and may be associated with CD4 cell depletion in FIV-MD-infected cats, as seen in HIV-1-infected humans.

Cognitive and emotional deficits in early stages of HIV infection: an event-related potentials study

1. In order to inventory different Event-Related Potentials (ERP) modifications in HIV-infection the authors have evaluated 23 HIV-positive subjects and 12 HIV-negative subjects. ERP were recorded during an auditory oddball task. 2. Electrophysiological results showed that the latency of the N100 component of the ERP was significantly increased in HIV-positive subjects compared to the HIV-negative subjects. The latency of the N200 component of the ERP showed a similar tendency which just failed to reach significance when considering HIV-positive subjects vs HIV negative subjects. This result was in agreement with the literature which reported increased latencies in HIV infection. 3. Considering all subjects the authors have observed a correlation between the amplitude of the P300 and the emotional deficit. This correlation was stronger in subjects who presented an emotional deficit and was independent of any other psychopathological symptom. 4. The use of ERP appeared to be a sensitive technique to detect subclinical manifestations in HIV asymptomatic subjects and therefore would help to identify subjects at higher risk for developing cognitive impairments.

Neurophysiological assessment of peripheral nerve and spinal cord function in asymptomatic HIV-1 infection: results from the UCMSM/Medical Research Council neurology cohort

As part of the Medical Research Council prospective study of the neurological complications of HIV infection, neurophysiological tests of spinal cord and peripheral nerve function were recorded in a cohort of homosexual or bisexual men. The studies included motor and sensory nerve conduction studies, vibration perception thresholds, somatosensory evoked potentials and motor evoked potentials elicited by magnetic stimulation. The results were compared with markers of immune function. The findings from 114 volunteers were analysed in a cross-sectional study. Fifty-nine were HIV-seropositive but asymptomatic, 26 had progressed to the symptomatic stages of HIV disease and 29 were persistently HIV-seronegative. There was some evidence of a mild sensory axonopathy in the symptomatic HIV-seropositive group. No differences were detected between the asymptomatic HIV-seropositive group and the HIV-seronegative comparison group. There were no consistently significant correlations between the neurophysiological measurements and CD4 counts and beta 2-microglobulin levels. On repeated testing, there was no evidence of a trend towards deterioration over a mean period of approximately 3 years in 36 HIV-seropositive subjects who remained asymptomatic compared with 22 HIV-seronegatives. These findings have failed to demonstrate neurophysiological evidence of spinal cord or peripheral nerve dysfunction in the asymptomatic stages of HIV infection.