Long-term Cognitive Outcomes in Susac Syndrome
Yoav Piura1, Noa Bregman2, Gitit Kavé3, Arnon Karni2, Hadar Kolb2, Ifat Vigiser2, Tamara Shiner2, Keren Regev2
1Assuta University Hospital, Ashdod, Israel., 2Neurology Institute, Tel Aviv Medical Center, Tel Aviv, Israel, 3Department of Education and Psychology, The Open University, Ra'anana, Israel
Objective:

Analyzing the cognitive impact of aggressive immunotherapy protocol in Susac syndrome rehabilitation.

Background:
Susac syndrome (SuS) is a rare autoimmune disorder mediated by the occlusion of micro-blood vessels in the brain, retina, and inner ear. Approximately 15% of cases present with the classic triad of CNS dysfunction, visual disturbances, and sensorineural hearing loss. While the literature is abundant about the severe, acute encephalopathy of SuS, not much is known about the extent of cognitive sequela in the post-era of efficient immunomodulatory treatment.
Design/Methods:
The registry of the Neuroimmunology Unit at Tel Aviv Sourasky Medical Center, Israel, was browsed for patients who met the suggested criteria of SuS diagnosis (definite and probable). Ten recovering SuS patients with an average of 2.9 (SD=1.41) years post-disease onset were assessed for global cognitive functions with a battery of cognitive tests. 

Further information was retrieved from the medical files, including scores on a cognitive screening test administered at the time of diagnosis, initial CNS involvement severity data, and brain MRI. 

Results:

Patients showed intact delayed memory (both verbal and non-verbal) but below-average scores on tests of executive functions (Stroop), and deficits in attention (MOXO) and copying (Rey-Osterrieth Complex Figure). Eight patients (80%) regained base occupational functionality. Results are discussed in light of the initial severity and extent of corpus callosum involvement on brain MRI.

Conclusions:
Study results suggest that the main cognitive sequela of SuS involves deficits in visual attention and executive functions possibly due to Corpus Callosum involvement. Additionally, this report supports a favorable prognosis for patients with SuS who receive a fast and efficacious immunomodulatory treatment protocol suggested in 2018 by Rennebohm at el.
10.1212/WNL.0000000000204949