Background: The HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is the most common neurological manifestation associated with Human T-cell Lymphotropic Virus type-1 (HTLV-1) infection. Although cognitive impairment has been highlighted in the spectrum of HTLV-1 neurological manifestations, it may go unnoticed in those who do not spontaneously report it. We aimed at evaluating the applicability of a self-perceived memory score (SMS) and the cognitive event-related potential (P300) for the early detection of cognitive impairment in HTLV-1-infected people.Methods: The SMS was measured by a 0-10 visual analog scale combined with a sad-happy faces rating scale. The higher the number, the better was the SMS. The P300 was obtained through an oddball paradigm with a mental counting task. The participants were 15(21,4%) individuals with HAM/TSP, 20(28,6%) HTLV-1-asymptomatic carriers, and 35(50%) seronegative controls.Results: SMS (p<0.001) and P300 latency (p<0.001) got progressively worse from asymptomatic to HAM/TSP. A SMS <7.2 points and a P300 latency >369.0 milliseconds were considered as altered result and indicated cognitive impairment. The HAM/TSP group showed the highest prevalence of altered P300 (80%) and SMS (87%). Interestingly, the asymptomatic group also presented signi cant higher prevalence of altered SMS (60%) and P300 (35%) when compared to controls (<10%). The frequency of cognitive impairment was 16 times higher in the asymptomatic group and 69 times higher in the HAM/TSP group when compared to controls.
Conclusion:The use of SMS in the medical consultation was a useful and easy-to-apply method to screen HTLV-1 infected subjects for everyday memory complaints.
BackgroundThe rst descriptions of the neurological disease associated with HTLV-1 infections were based on the motor function assessed by mobility and strength disability [1, 2]. The HTLV-1 associated myelopathy / tropical spastic paraparesis (HAM/TSP) is a chronic, slow-progressing neurological in ammatory disease that affects approximately 4% of the infected individuals [3, 4]. However, the prevalence of neurological disorders that do not meet the criteria for de nite HAM/TSP, such as urinary disorders, sexual dysfunction and skin lesions, can occur in around 30% of those individuals classi ed as HTLV-1-asymptomatic carriers [4][5][6]. In fact, non-medullary symptoms have been neglected in the HTLV-1 infection [7].Recent evidences have showed that HTLV-1 is related to a complex of neurological manifestations that are not limited to the clinical spectrum of HAM/TSP, affecting all the segments of the central nervous system to a greater or lesser extent [3,[8][9][10][11][12][13][14][15][16][17][18]. In this context, cognitive impairment has been reported as one of the manifestations of the HTLV-1 infection [11,13,[19][20][21][22][23][24]. On the other hand, HAM/TSP remains as the most important neurological disease associated with 26]. Therefore, cognitive impairment can be underdiagnosed and may go unnoticed in those indivi...