The frequency and characteristics of multiple sclerosis misdiagnosis referrals to a tertiary center in Saudi Arabia.

OBJECTIVE

To assess the frequency, contributing factors, and clinical implications of multiple sclerosis (MS) misdiagnosis among referrals to a tertiary MS center in Saudi Arabia.

METHODS

We retrospectively reviewed records of 416 patients referred to the MS clinic at King Fahad Medical City, Riyadh, between January 2018 and January 2024. After excluding 12 patients due to incomplete data, 404 remained. Referrals were categorized as established MS, possible MS, clinically isolated syndrome (CIS), or radiologically isolated syndrome (RIS). Diagnostic reassessment was performed using the 2017 McDonald criteria. Misdiagnosed cases were reclassified, and alternative diagnoses recorded.

RESULTS

Of 257 patients referred with an established MS diagnosis, 17 (6.6 %; 95 % Confidence Interval (CI): 4.1-10.4) were misdiagnosed. Among 137 referrals for a possible MS, 46 (33.6 %; CI: 26.0-41.9) had non-MS conditions. Common alternative diagnoses included nonspecific white matter lesions (41.2 %) and migraine (29.4 %). Cerebrospinal fluid (CSF) oligoclonal bands were positive in 78.2 % of confirmed MS cases and 6.7 % of misdiagnosed cases. Unnecessary MS treatment was given to majority of misdiagnosed patients, costing 849,921 SAR (∼226,645 USD).

CONCLUSION

MS misdiagnosis is frequent, especially in atypical cases or non-specialist evaluations. Early referral and strict use of McDonald's criteria may reduce diagnostic errors and healthcare costs.