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.