A 41-year-old woman was hospitalized in 1939 with neurologic signs from which there was complete recovery over a two-year period. In 1965 she was readmitted because of increasing forgetfulness and inability to care for herself; there were no neurologic deficits. In June 1970 torticollis developed and persisted until her death 15 months later. No cerebellar signs were elicited, but increased muscle tone was prominent.
The brain showed remarkable flattening of the inferior surface of the cerebellum; the pons was small. The medullary substance of the cerebellum and each brachium pontis appeared completely demyelinated. Transverse fibers were apparently absent in the central basis pontis.
Microscopically in addition to the pontocerebellar atrophy there was degeneration of the vestibular system, reticular formation of the medulla oblongata and medial longitudinal fasciculi. The inferior olives showed only moderate neuronal degeneration in the caudal areas. Basal ganglia and thalamus showed some involvement in the pathological process.
It is postulated that the vestibular-reticular system atrophy was the anatomic substrate for the torticollis, and apparently overshadowed cerebellar signs, which are ordinarily associated with pontocerebellar atrophy.