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

The motor evoked potential in aids and HAM/TSP State of the evidence

OBJECTIVE: We aimed to better understand the involvement of the corticospinal tract, assessed by non-invasive transcranial stimulation, in order to determine the actual involvement of the motor system in patients with HAM/TSP and AIDS. METHOD: An exhaustive MEDLINE search for the period of 1985 to 2008 for all articles cross-referenced for "HTLV-I, HTLV-II, HTLV-III and HIV, HIV1, HIV2, evoked potential, motor evoked potential, high voltage electrical stimulation, transcranial magnetic stimulation, magnetic stimulation, corticomotor physiology, motor pathways, acquired immunodeficiency syndrome, AIDS, SIDA, tropical spastic paraparesis, HTLV-I-associated myelopathy, HAM, TSP, and HAM/TSP" were selected and analysed. RESULTS: Eighteen papers published in English, Spanish, Portuguese, French and Japanese were identified. Only the central motor conduction time has been analyzed in seropositive patients to human retroviruses. The investigations done on HAM/TSP support the involvement of the pyramidal tract mainly at lower levels, following a centripetal pattern; in AIDS, such an involvement seems to be more prominent at brain levels following a centrifugal pattern. CONCLUSION: The central motor conduction time abnormalities and involvement differences of the corticospinal tract of patients with AIDS and HAM/TSP dissected here would allow to re-orient early neurorehabilitation measures in these retroviruses-associated neurodegenerative disorders. Besides this, more sophisticated and sensitive non-invasive corticospinal stimulation measures that detect early changes in thalamocortical-basal ganglia circuitry will be needed in both clinically established as well as asymptomatic patients at times when the fastest corticospinal fibers remain uninvolved.

Behavioral and neurophysiological hallmarks of simian immunodeficiency virus infection in macaque monkeys

Macaque monkeys infected with various neurovirulent forms of simian immunodeficiency virus (SIV) represent highly effective models, not only of systemic acquired immunodeficiency virus (AIDS), but also neuroAIDS. Behavioral studies with this model have clearly established that SIV-infected monkeys show both cognitive and motor impairments resembling those that have been reported in human immunodeficiency virus (HIV)-infected humans. This paper combines data from a number of behavioral studies in SIV-infected macaque monkeys to obtain an overall estimate of the frequency of impairments in various motor and cognitive domains. The results were then compared to similar data from studies of HIV-infected humans. Whereas cognitive functions are most commonly impaired in HIV-infected humans, motor function is the domain most commonly impaired in SIV-infected monkeys. Electrophysiological studies in SIV-infected macaques have revealed deficits in motor-, somatosensory-, visual-, and auditory-evoked potentials that also resemble abnormalities in human HIV infection. Abnormalities in motor-evoked potentials were among the most common evoked potential deficits observed. Although differences in behavioral profiles of human HIV disease and SIV disease in monkeys exist, the results, nevertheless, provide strong validation for the use of macaque models for translational studies of the virology, immunology, pathophysiology, and treatment of neuroAIDS.

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.

Progressive peripheral and central sensory tract lesion in HIV-infected patients evidenced by evoked potentials (a three-year follow-up study)

OBJECTIVE

To investigate progression of peripheral and central sensory tract lesion and its correlation to immunological deterioration.

METHODS

Clinical and neurophysiological investigation (evoked potentials of the median and tibial nerve) and immunological parameters (CD4-cells, beta 2-microglobuline) were followed up in 160 patients (24 females, 136 males, HIV infection for 2.7 +/- 2.3 years, mv +/- 1 sd) up to four times over approximately 3 years regardless of disease stage and evidence of neurological symptoms. Recordings were done using needle electrodes over the Th12 and C7 spinous process and from the scalp (10/20 system) in the conventional manner. Statistical analysis was performed intraindividually and in comparison to normal laboratory values (n = 96).

RESULTS

All parameters deteriorated during the follow-up period. Statistical analysis showed significant differences between probands and patients for evoked potentials, but also a significant deterioration for evoked potentials after three years at the end of the follow-up study. A significant correlation between progressive impairment of evoked potentials and laboratory data was found.

CONCLUSION

HIV infection induces a progressive lesion of the ascending sensory tracts. The results indicate a peripheral neuropathy as well as a progressive lesion of the ascending central sensory tracts. Pathogenesis of polyneuropathy and of central sensory tract lesion is up to now conjectural. Laboratory investigations indicate a clear-cut correlation between immunological alterations induced by HIV infection and its neurologic manifestation on ascending sensory tracts.