CLINICAL/SCIENTIFIC NOTES Acute toxic limbic encephalopathy following glyphosate intoxication Vincent Planche, MD, PhD, Sylvain Vergnet, MD, Nicolas Auzou, PhD, Marie Bonnet, MSc, Thomas Tourdias, MD, PhD, and François Tison, MD, PhD Neurology ® 2019;92:1-3. doi:10.1212/WNL.0000000000007115 Correspondence Dr. Planche vincent.planche@ u-bordeaux.fr A 66-year-old man, with a history of Wolff-Parkinson-White syndrome, coronary artery disease, left partial colectomy for polyps, and alcohol abuse (≈50 g/d), attempted suicide by ingestion of commercially available glyphosate (Round-Up, ≈200 mL). He was admitted to the emer- gency ward for monitoring and hyperhydration. First clinical and biological workup and gastric endoscopic examinations were normal. Two days later, he became disoriented in space, with anterograde amnesia. He progressively became agitated without confabulation, hallucination, ataxia, ophthalmoplegia, or clinical sign of hepatic encephalopathy. He was unsuccessfully treated with IV benzodiazepines and sup- plemented by vitamins B 1 and B 6 given his medical history (serum thiamine concentration was normal when it was dosed on day 5). EEG was normal (except beta activity related to ben- zodiazepines administration). MRI showed bilateral hippocampal fluid-attenuated inversion recovery hypersignal (figure, A), but no brainstem, diencephalic, or mammillary lesion sug- gestive of Wernicke-Korsakoff syndrome. Infectious, autoimmune, or paraneoplastic limbic encephalitis were ruled out: CSF examination was normal with negative bacterial cultures and viral PCR, no intrathecal immunoglobulin synthesis, no onconeural or antineuropil antibodies, and finally whole-body CT scan found no tumor. Because of the possibility of seronegative autoimmune limbic encephalitis, a course of IV immunoglobulins (2 g/kg for 5 days) was administered, but without any clinical improvement. One month after glyphosate ingestion, the patient was evaluated in our neurologic department for persistent anterograde memory loss. Episodic memory was severely impaired (-2 SD to -3 SD) when using visual and verbal tests (Wechsler Memory Scale–IV [WMS-IV], Delayed Matching to Sample, and Free and Cued Selective Reminding Test). However, working memory (WMS-IV and digit-span task from Wechsler Adult Intelligence Scale–IV [WAIS-IV]), language (naming test), praxis, and executive functions (Trail-Making Test [TMT] A and B and Stroop tests) were preserved. Information processing speed was slightly impaired (-1 SD on Symbol Digit Modalities Test and coding of WAIS-IV). CSF tau concentration was higher than the upper limits of the laboratory (>2,400 pg/mL). Cerebral 18 F-FDG-PET/CT found anterior cingulate, medial temporal, and parietal cortices hypometabolism (figure, B). This pattern of PET hypometabolism was interpreted as compatible with Alzheimer disease but CSF β-amyloid and phosphorylated tau concentrations were in the normal range. Progranulin plasma level and C9ORF72 sequencing were normal. Six months after glyphosate ingestion, neuropsychological tests revealed unchanged per- formances on the same tests. Hippocampal atrophy (-23% in 5 months, on hippocampal volumetry using Volbrain software, volbrain.upv.es) was measured on brain MRI, while global brain volume remained unchanged (figure, C). CSF tau concentration almost returned to normal (figure, D). One year later, neuropsychological tests were still unchanged except slightly decreased performances in mental flexibility (TMT-B). From the Institut des Maladies Neurod´ eg´ en´ eratives (V.P., S.V., N.A., M.B., F.T.), CNRS UMR 5293; Universit´ e de Bordeaux (V.P., S.V., N.A., M.B., T.T., F.T.); CHU de Bordeaux (V.P., S.V., N.A., M.B., T.T., F.T.); and Neurocentre Magendie (T.T.), INSERM U1215, Bordeaux, France. Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article. Copyright © 2019 American Academy of Neurology 1 Copyright © 2019 American Academy of Neurology. Unauthorized reproduction of this article is prohibited. Published Ahead of Print on February 8, 2019 as 10.1212/WNL.0000000000007115