A 54-year-old male truck driver presented with a recent history of difficulty walking, and particularly climbing the single step into his truck. This difficulty was accompanied by lower back pain, which extended into his legs, urinary hesitancy and constipation. An ulcer was also noted on the buccal surface of his lower lip. On examination of the lower limbs, there was evidence of bilateral hypotonia and global weakness (grade 3–4/5). Knee jerks were normal, ankle jerks absent and plantar responses were flexor with no evidence of a sensory deficit. Anal tone was noted to be decreased. The patient was pancytopenic with a CD4 count of 30 (4%) and a human immunodeficiency virus load of >100,000. He had not yet been commenced on highly active anti-retroviral therapy. Cytology of the cerebrospinal fluid revealed 3 polymorphs, 6 erythrocytes