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

Abstract

-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.KEY WORDS: AIDS, HAM/TSP, HIV, HTLV-I, transcranial magnetic stimulation, non-invasive transcranial stimulation, pyramidal tract. El potencial evocado motor en SIDA y HAM/PETResumen -Objetivo: Investigar el compromiso del tracto piramidal, evaluado por estimulación trascranial no invasiva, en pacientes afectados por SIDA y HAM/TSP. Método: Se realizó una búsqueda en la base de datos MEDLINE, que abarcó el período de 1985 a 2008; se incluyeron los términos "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". Resultados: Se obtuvieron 18 artículos publicados en inglés, español, portugués, francés y japonés. El tiempo de conducción central es el único parámetro que se ha estudiado en individuos seropositivos a retrovirus humanos. Las investigaciones hechas en HAM/PET apoyan el compromiso del tracto piramidal, principalmente a nivel dorso-lumbar, de manera centrípeta. En SIDA, el compromiso parece ser mas prominente a nivel cortical, siguiendo un patrón centrifugo. Co...

A new neurometric dissection of the area-under-curve-associated jiggle of the motor evoked potential induced by transcranial magnetic stimulation

“…The amplitude of the recorded signal is a function of the frequency and temporal coherence of the neural activity that controls that specific muscle [3]. Despite the usefulness of the abovementioned parameters in studying the function and dysfunction of the neural pathways at rest and during activity [4][5][6][7][8], the variability of the MEP elicited by TMS or the "M-jiggle" [9][10][11], defined as the variation of the size of the evoked potential from one stimulus to the next, has precluded its wider use in diverse settings.…”

Central motor conduction studies in patients with spinal cord disorders: a review

“…The authors concluded that, in the retrovirusassociated neurodegenerative disorders, these differences in corticospinal tract involvement of patients with AIDS and HAM/TSP may help to orient early neurorehabilitation measures. 43 Nutritional/metabolic myelopathies Subacute combined degeneration (vitamin B12 deficiency). The neurological manifestations of vitamin B12 deficiency primarily result from the degeneration of the posterior and lateral columns of the spinal cord.…”