Superficial siderosis of the central nervous system: secondary progression despite successful surgical treatment, mimicking amyotrophic lateral sclerosis. Case report and review.

Superficial siderosis of the central nervous system is a rare disorder with hemosiderin deposition in the spinal and cranial leptomeninges and subpial layer, mostly from repetitive subarachnoid hemorrhage. Progressive sensorineural deafness, cerebellar ataxia, and pyramidal signs comprise the typical clinical presentation. We describe a 47-year-old patient, who showed initial 2-year improvement after successful occlusion of an intradural bleeding source at T4. Secondary progression of symptoms without further bleedings was noted thereafter, with a clinical picture of amyotrophic lateral sclerosis. This case illustrates that the disease may progress secondarily even without re-bleedings, and that secondary progression might be due to a similar pathomechanism as in amyotrophic lateral sclerosis.