Bede P, Chipika RH, Finegan E, et al. - In this prospective longitudinal imaging study with 100 people with amyotrophic lateral sclerosis (ALS), 33 with primary lateral sclerosis (PLS), 30 with frontotemporal dementia (FTD) and 100 healthy controls, experts intended to systematically characterise brainstem involvement in ALS and PLS, using both healthy- and disease controls in a prospective longitudinal study design. In ALS, computational brainstem imaging captured the degeneration of both white and grey matter components. The longitudinal data designate progressive brainstem atrophy over time, emphasizing the biomarker potential of quantitative brainstem measures in ALS. At a time when a number of clinical trials are undertaken globally, there is an unusual requirement for accurate biomarkers to monitor disease progression and identify response to therapy. Thus, brainstem imaging is an encouraging addition to candidate biomarkers of ALS and PLS.