Evidence of Spinal Cord Damage in Human T Cell Lymphotropic Virus Type 1-Infected Subjects Without Motor Disability

Spinal cord (SC) narrowing has been documented in patients with human T cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy (HAM). However, it remains uncertain whether individuals who present with lower urinary tract symptoms (LUTSs) without motor disability (probable HAM) exhibit damage to the central nervous system. These patients typically experience nocturia, urgency, incontinence, and, less frequently, an arreflexic bladder, which requires intermittent catheterization for voiding. The aim for the present study was to investigate the effectiveness of magnetic resonance imaging with tractography in detecting abnormalities in HTLV-1-infected individuals with LUTS. The study participants included those with probable HAM (n = 39), HTLV-1 carriers (HCs; n = 41), and seronegative (SN) controls (n = 12). Magnetic resonance imaging with diffusion tensor imaging and tractography was performed, with two regions of interest positioned side-by-side at T5 and T12-L1. Measurements included the SC area, mean diffusivity, and fractional anisotropy (FA). No significant differences were found between groups regarding age or sex (P >0.05). The medians and interquartile ranges for the thoracic SC area were 0.41 (0.39-0.45), 0.36 (0.30-0.40), and 0.33 (0.27-0.36) in SN controls, HCs, and those with probable HAM, respectively (P <0.05). The lumbar SC area was smaller in patients with probable HAM compared with HCs and SN controls. Furthermore, the median FA in the lumbar region was significantly lower in patients with probable HAM (P <0.05). Urinary dysfunction is the most common manifestation in probable HAM, and the present study reveals SC narrowing in these patients, despite the absence of motor disability.