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Presentation type	E-poster
Title	The influence of internuclear ophthalmoplegia on the results of the Symbol Digit Modalities Test in patients with multiple sclerosis.

Purpose	Internuclear ophthalmoplegia (INO) and cognitive decline are both frequent manifestations in multiple sclerosis (MS). The Symbol Digit Modalities Test (SDMT) is the most used cognitive test in MS patients and relies on visual scanning. The purpose of this study was to investigate the influence of abnormal eye movements in INO on the SDMT score in MS patients.
Methods	In this retrospective, observational, cross-sectional study, data of 199 MS patients from the Amsterdam MS cohort were analyzed. The presence of INO was detected using infrared oculography. All patients underwent a neurological and neuropsychological examination, an MRI scan, and an OCT scan. Using multiple linear regression analyses, the influence of INO on the SDMT score and other neuropsychological tests was studied.
Results	In 62 patients, the diagnosis of INO was made. The SDMT score was significantly lower in the INO group compared to the non-INO group. The corrected regression model with the VDI Pv/Am left (which is a parameter to detect right INO) shows a significant influence of a right INO on the SDMT score. Other cognitive tests were also significantly affected by INO.
Conclusion	Half of the patients with a right INO scored clinically significantly worse on the SDMT due to their eye movement disorder. This means that the SDMT score reflects disturbed eye movements in addition to cognition. Caution should be exercised in interpreting the SDMT score if a right INO is present. We emphasize the importance of the detection of INO in neuro-ophthalmological examinations, given important implications in other domains of medicine.
Conflict of interest	No

Authors 1

Last name	KEYTSMAN
Initials	E
Department	Vrije Universiteit Brussel
City	Jette

Authors 2

Last name	Hof
Initials	S
Department	MS Centre
City	Amsterdam

Authors 3

Last name	Van Lint
Initials	M
Department	University Hospital Brussel
City	Jette

Authors 4

Last name	Strijbis
Initials	E
Department	MS Centre
City	Amsterdam

Authors 5

Last name	Schoonheim
Initials	M
Department	MS Centre
City	Amsterdam

Authors 6

Last name	Van Schependom
Initials	J
Department	AI-supported modeling in clinical sciences, VUB
City	Jette

Authors 7

Last name	Van Oosten
Initials	B
Department	MS Centre
City	Amsterdam