HTLV-I-associated myelopathy (HAM)/tropical spastic paraparesis (TSP) withamyotrophic lateral sclerosis-like manifestations

To clarify the existence of HAM/TSP presenting amyotrophic lateral sclerosi s (ALS)-like manifestations, we assayed HTLV-I proviral load in peripheral blood mononuclear cells (PBMC) in 15 patients with anti-HTLV-I antibody in serum and ALS-like manifestations (upper motor neuron involvement in at lea st one region and lower motor neuron involvement in at least two limbs) by quantitative PCR, and compared the proviral load with that of 233 HAM/TSP p atients and of 213 HTLV-I carriers. Five of 15 patients with ALS-like manif estations had proviral loads as high as those in the 233 patients with HAM/ TSP. Anti-HTLV-I antibody in cerebrospinal fluid (CSF) was present in all o f five patients. The proviral load in the remaining 10 patients was similar to that in HTLV-I carriers. Four of five patients with a high proviral loa d met the diagnostic criterion of HAM/TSP except for lower motor neuron inv olvement. These four patients showed high neopterin levels in CSF. On the b asis of HTLV-I proviral load in PBMC and the clinical symptoms, our tentati ve conclusion is that these four patients are HAM/TSP presenting ALS-like m anifestations.