Hypothesis / aims of study
Introduction: spinal cord (SC) narrowing is documented in patients with tropical spastic paraparesis/human T cell lymphotropic virus type 1 associated myelopathy (HAM/TSP). It is not consensual that patients without criteria for HAM/TSP present SC lesions. Our hypothesis is that the magnetic resonance images (MRI) could recognize lesions or abnormalities of tractography parameters in patients with lower urinary symptoms (LUTS) without gait impairment, defined as probable HAM/TSP. Objective: investigate the role MRI with tractography in detecting SC abnormalities in HTLV-1 patients.
Study design, materials and methods
Methods: patients followed in a cohort study were selected and grouped according to Castro-Costa classification: 33 HTLV-1 asymptomatic carries, 31 probable HAM/TSP, 27 definite HAM/TSP and 11 seronegative control. They were submitted to MRI (Siemens 1.5T), with two region of interest (ROI) positioned side by side at T5 and T12-L1. The images were analyzed by 2 neuroradiologists that established the measurements of the SC (antero-posterior (AP) and latero-lateral (LL) radius and area) and classified as normal or narrowed. Diffusion tensor image (DTI) and fractional anisotropy (FA) were stablished by the manufactory application. LUTS were evaluated by overactive symptoms score (OABSS) and bladder diary.
Results
Results: the majority of patients concluded the MRI exams (99/116). The mean age (standard deviation – SD) was 56.2 (14.3). There was no difference between groups regarding age and sex. The mean (SD) OABSS was 1.09 (0.91), 7.42 (4.15), 6.8 (4.64) in asymptomatic carries, probable and definite HAM/TSP, respectively (P<0.01). The mean (SD) of SC thoracic area were 0.38 (0.09), 0.33 (0.08), 0.27 (0.09) and 0.40 (0.05) for asymptomatic, probable HAM, definite HAM/TSP and seronegative controls, respectively (P<0.01). The mean (SD) of SC lumbar area were 0.60 (0.10), 0.55 (0.11), 0.0.53 (0.11) and 0.64 (0.09) for asymptomatic, probable HAM, definite HAM/TSP and seronegative controls, respectively (P=0.01). Mean (SD) fractional anisotropy values of thoracic field were 616.47 (99.30) in asymptomatic, 591.21 (104.82) in probable HAM/TSP, 503.77 (96.60) in definite HAM/TSP and 616.91 (166.85) in seronegative controls (P = 0.002). Mean (SD) fractional anisotropy values of lumbar field were 503.88 (121.09) in asymptomatic, 452.47 (82.93) in probable HAM/TSP, 439.98 (98.65) in definite HAM/TSP and 550.95 (78.30) in seronegative controls (P = 0.008).
Interpretation of results
Although motor disability is not present in patients with only urinary symptoms (probable HAM/TSP), they present SC disorders demonstrated on MRI.