In 2010, we reported the successful clinical outcome related to a 20-month course of intravenous, cyclical ceftriaxone, in a patient with adult-onset Alexander's disease. We now provide evidence that the progression of the patient's signs/symptoms was halted and reversed with a 4-year-long extension of the trial.The patient's clinical signs/symptoms were evaluated before the start and every 6 months for 6 years. For the early 2 years, without therapy, and for the following 4 years, after intravenous ceftriaxone 2 g daily, for 3 weeks monthly during the initial 4 months, then for 15 days monthly.Gait ataxia and dysarthria were assessed clinically on a 0 to 4 scale. Palatal myoclonus and nystagmus/oscillopsia were monitored by videotape and a self-evaluation scale. The degree of disability, measured by a modified Rankin scale, and the brain MRI were periodically evaluated.Before ceftriaxone therapy, in a 2-year period, gait ataxia and dysarthria worsened from mild to marked, palatal myoclonus spread from the soft palate to lower facial muscles, and the patient complained of oscillopsia. After 4 years of ceftriaxone therapy, gait ataxia and dysarthria improved, from marked to mild at clinical rating scales. The palatal myoclonus was undetectable; the patient did not complained of oscillopsia and declared a progressively better quality of life. Ceftriaxone was safe.This case report provides Class IV evidence that intravenous cycles of ceftriaxone may halt and/or reverse the progression of neurodegeneration in patients with adult-onset Alexander's disease and may significantly improve their quality of life.