This is a 57-year old-female with seronegative lupus (on hydroxychloroquine and belimumab) who presented with acute onset dysarthria and gait instability. Stroke code imaging was negative. She tested positive for Influenza A and oseltamivir was started, later changed to peramivir. Her mental status declined within hours requiring intubation.

Magnetic resonance imaging (MRI) demonstrated symmetrical T2 hyperintense lesions with diffusion restriction at the pons. Repeat MRI two days after disclosed marked progression of the symmetrical brainstem edema, involving the temporal lobes through the hippocampi. Cerebrospinal fluid (CSF) revealed protein of 181. She was transferred to a tertiary care hospital.

Patient was unresponsive on unsedated exam. Diffuse myotonia was observed, with creatinine kinase (CK) over 70,000. EEG revealed multiple generalized seizures with focal onset over the left temporal lobe. Repeat CSF disclosed protein of 665 and few cells. Serum and CSF revealed elevations in interleukin-6 in the serum (213) and CSF (104) and was negative for toxins, ganglioside antibodies, and antibodies associated with autoimmune encephalitis (Mayo Clinic ENC2 panel). Profound refractory hyperkalemia resulted in cardiac arrest.

Autopsy revealed multifocal cerebral and cord hemorrhage with bland coagulative necrosis consistent with infarction without lymphocytic or neutrophilic infiltration or malignancy. There was acute lung injury attributed to influenza, and renal changes consistent with Class II lupus nephritis.