Acquired Chronic Internal Hydrocephaly
Patient was 60 years old. At one point possessed considerable intellect as well as musical ability and ability to work. Later in life became blind, partially deaf, with some spasticity of lower limbs. Never had convulsive attacks, fair health aside form brain disease.
Brain 1,240 g when emptied, contained 2,400 cubic centimeters of fluid.
You can see here the extreme results of the blockage of the cerebral aqueduct connected to the fourth ventricle.
This man’s hydrocephaly developed later in life, when his skull was fully formed, so outwardly he did not show deformity (aside from a slight bulging of the eyes). However, the pressure of the cerebrospinal fluid (CSF) caused his optic chiasma to become flattened, shrunken, and greyish in color.
Interestingly, though this man lost many of his basic functions due to the increasing severity of his hydrocephalus over the last part of his life (as more and more CSF became stuck in his fourth ventricle), he actually retained a fair amount of intelligence and ability to reason and speak. This is because his frontal and prefrontal cortex (his frontal lobe) were almost completely spared the effects shown in the central and posterior cerebrum (parietal, temporal, limbic, and occipital lobes).
If you look at the position of the fourth ventricle in the brain (just above the cerebellum, behind the brainstem, lower than the other ventricles), you can see why the occipital lobe, which processes sight, would be affected before the other regions of the brain, and why this patient experienced those specific symptoms, yet still retained his intelligence.
Illustrations of the Gross Morbid Anatomy of the Brain in the Insane. I.W. Blackburn, 1908.
ETA: The hydrocephalus is labeled “congenital”, because the pathologist supposed that the blockage of the cerebral aqueduct was due to a benign tumor, present from birth, that had simply grown large enough to cause problems.