HTLV-I is associated with a broad spectrum of manifestations, including tropical 
spastic paraparesis and adult T-cell leukemia/lymphoma. Arnold Chiari syndrome 
is a condition characterized by herniation of the cerebellar tonsils through the 
foramen magnum. This condition should be suspected in all patients with headache 
and impaired motor coordination. Syringomyelia is a developmental anomaly that 
leads to the formation of an intramedullary cavity. Its clinical presentation is 
classically characterized by syringomyelic dissociation of sensation, with 
suspended distribution in the proximal portion of the trunk and upper limbs and 
preservation in other regions. We report here a case of association of the three 
diseases, which is rare in clinical practice, illustrating the difficulty in the 
diagnosis and therapeutic management of these conditions.