Superficial siderosis (SS) is a rare disease caused by hemosiderin deposition in central nervous system and typically leads to neurological dysfunction and progressive irreversible symptoms. Multiple Sclerosis is most common demyelinating disease which usually courses with relapses and remissions but some patients can have a progressive course. Progression in MS patients is defined as a worsening of functional systems over one year.
We are presenting MS patient since 1994 who developed in last three years a progressive ataxia which was initially attributed to MS progression, nevertheless MRI showed hypointensities on cerebellum that led us to diagnose SS. Recognizing this entity is important because it could be a cause of pseudo progression in MS patients.
We want to disclose the superficial siderosis as an unusual cause of pseudo-progression in patients affected by multiple sclerosis.
A 63 year-old woman with history of relapsing-remitting MS (RRMS) treated with Glatiramer acetate. She was stable until 2017, but since then she started to notice clumsiness of her both hands and difficulties to walk. She even had some falls because of unsteady gait.
Her Expanded Disability Status Scale (EDSS) passed from 2.0 to 4.5 due to worsening of cerebellar functional system and the using of a cane for walking. Over next three years she had progressive impairment of gait and coordination of all limbs. Sensorineural hearing loss of unknown cause was also diagnosed during this time. On last neurological examination she presented mild cerebellar dysarthria, moderate ataxia of all limbs, ataxic gait and need to walk with bilateral support. Other signs of the neurological examination were mild decrease of vibration and brisk reflexes on lower extremities. Currently her EDSS is 6.5
A cerebellar relapse was ruled out as cause of her symptoms because of progressive course, no recovery after steroids and no evidence of new T2 lesions on cerebellum. A RRMS turning into SPMS was initially accepted as responsible of her worsening.
A comprehensive approach was performed, as there was an almost exclusive deterioration of the cerebellar functional system. So, a new brain MRI was requested and hemosiderin effect was seen along cerebellar folias. This finding was the key to diagnose superficial siderosis.
A neuroaxis MRI evaluation was done and there was no evidence of SS in other parts of CNS nor evidence of chronic bleeding that causes SS on cerebellum.
We proposed to initiate treatment with Deferiprone but the patient rejected to take it after we exposed lack of clear effectiveness. She is still being treated with Glatiramer acetate for MS.
Superficial siderosis can be a mimic of progression in patients affected by multiple sclerosis, that is why we recommend to take into account this entity in those patients with progressive worsening of walking secondary to exclusive affectation of cerebellar functional system.