CONTRALATERAL EARLY BLINK REFLEX IN PATIENTS WITH HTLV-I-ASSOCIATED MYELOPATHY TROPICAL SPASTIC PARAPARESIS

Thirty-two Japanese patients with HTLV-I-associated myelopathy/ tropic al spastic paraparesis (HAM/TSP) were studied by means of the electric ally elicited blink reflex and three responses (R1, R2, R3) were regis tered. 69% of the patients displayed a uni- or bilateral crossed R1 re sponse (R1k) as compared to 11% in the control group. A positive corre lation between R1k and an exaggerated jaw jerk reflex was found in the patients. Central abnormalities of the nervous system with diminished presynaptic inhibition acting in the interneuronal input of the brain stem of HAM/TSP patients was the most likely cause. It could lead to t he unmasking of crossed trigemino-facial pathway reflex which is prese nt in the normal population from birth. These results strongly support the supraspinal involvement of the central nervous system (CNS) in HA M/TSP more than usually thought.