Blocq and Marinescu were the first physicians to describe extracellular neuritic plaque deposits in the grey matter of the brain. Also the two identified a case of Parkinsonian tremor caused by a tumor in the substantia nigra of the brain. With Marinescu and bacteriologist Victor Babeş (1854-1926), Blocq published an important work on the pathological histology of the nervous system titled Atlas der pathologischen Histologie des Nervensystems.