Paraneoplastic Neurologic syndromes are immune-mediated attacks, accosted with systemic cancer, that attack neuronal tissues evolving over days-weeks causing constellation of neurological symptoms. One such rare syndrome is PLE which usually presents with seizures, Limb-paresis, Cognitive Impairment (CI) and/or psychiatric disturbances. We report a case of a female who presents only with acute onset of memory loss mimicking transient global-amnesia (TGA).

53-year-old female history of breast cancer, active neuroendocrine lung cancer metastasis to bone s/p 2-cycles chemotherapy (carboplatin/etoposide/atezolizumab) presents with acute onset memory-loss. She awoke, difficulty remembering events of past 1-year. Denied other symptoms. Her exam, vital-signs, labs (CBC/BMP/B12/B6/B1/thyroid panel) and EEG were unremarkable. She was able to form new memories but her retrograde-amnesia continued >24hrs. MRI: questionable T2/FLAIR hyperintense signal, right temporal-lobe. LP: normal opening-pressure, elevated WBC-20 and protein-123, normal glucose. Meningoencephalitis panel:negative. 2-days following presentation she developed seizures and CI. Repeat EEG: multifocal sharp-spike waves with epileptiform discharges. Antiepileptics were initiated. Acyclovir started prophylactically and Low-dose Solumedrol for suspicion of check point inhibitor induced versus autoimmune versus PLE. There was mild improvement. Repeat LP: improvement in WBC-14 and Protein-75. A review of paraneoplastic Ab-panel from previous LP: high ANNA-1 titer (1:64). Repeat MRI: multifocal hyperintensities. Discontinued acyclovir and started IVIG. Her mentation/amnesia improved.

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PLE is a rare and devastating disorder that evolve over days-weeks presenting as constellation of neurological symptoms. Here we present a case to exemplify acute presentation with abrupt onset of amnesia and no other symptom. TGA was ruled-out, given Retrograde>anterograde amnesia for >24hrs. Initial workup including MRI/EEG/initial CSF labs were inconclusive. Steroids were delayed due to higher-likelihood of an infectious cause. Pending CSF Autoimmune-labs later revealed presence of ANNA-1 (Anti-Hu). This highlights importance of considering PLE in patients with underlying small-cell lung cancer and progressive neurological symptoms in order to prevent delay of treatment.