Bertil Delsaut

Background. Froin’s syndrome (FS) is a rare entity with uncertain prevalence and prognosis, defined by a pathognomonic triad: cerebrospinal fluid (CSF) xanthochromia, elevated protein levels in the CSF, and hypercoagulated CSF, usually obtained through lumbar puncturing below the level of a partial or complete spinal block. Methods. We conducted a comprehensive review of the literature on FS from its first description in 1903 to December 2023, utilizing PubMed and Google Scholar, and included two new cases from our clinical practice. Results. We describe two patients who suffered from Froin’s syndrome secondary to spinal abscesses. According to our review, FS is caused by neoplasia in 33% of cases, non-malignant mechanical causes in 27%, infections in 27%, non-infectious inflammatory processes in 6%, and vascular in 6%. The most prevalent symptoms are paraplegia/paraparesis (64%), back pain (38%), altered mental state and/or confusion (23%), sciatica (17%), headaches (17%), leg sensory defects (17%), and urinary retention (14%), and are thought to be linked with the underlying causes rather than the CSF characteristics. FS holds a poor prognosis: only 22% recuperate fully after treatment, 22% die due to the cause leading to FS, and 14% retain sequelae. Conclusions. Xanthochromia and proteinorachia >500 mg/dL are not specific to any single pathological condition, but indicate defective CSF recirculation and spinal block, causing diffusive and/or inflammatory processes resulting in the hyperproteinosis and coagulation of the CSF. We reviewed the pathophysiology, etiologies, symptoms, outcomes, and workups of Froin’s syndrome according to the existing medical literature.