A 59-year-old woman with systemic lupus erythematosus (SLE) presents to the emergency department (ED) with headache, confusion, and mild somnolence. Her husband states that she has been complaining of a constant, severe headache for the past 2 days. She also has not complained of nausea, dizziness, chest pain, shortness of breath, abdominal pain, or muscular pain. She is currently taking hydroxychloroquine and has not taken any glucocorticoids in the past 6 months.
The patient’s SLE symptoms have been mostly mucocutaneous, and she has had brief periods of migratory, polyarticular, and symmetric arthritis. She has no history of thromboembolic disease, vasculitis, renal impairment, gastrointestinal disease, or neuropsychiatric manifestations of SLE.
On examination, the patient is noted to be somnolent but easily aroused. She is afebrile and has elevated blood pressure (172/93 mm Hg) but no neck rigidity. A characteristic rash is noted on her face. Fundoscopic examination, pupillary size, and pupillary reflexes are within normal limits. Deep tendon reflexes are brisk in the lower extremities bilaterally, and positive Babinski sign is elicited. No focal neurologic deficits are found.
Her complete blood count reveals mild leukopenia, normocytic anemia, and mild thrombocytopenia. Basic metabolic panel results are notable for creatinine level 1.4 mg/dL and hypomagnesemia. Urinalysis is within normal limits. Lumbar puncture (LP) reveals clear cerebrospinal fluid, with mildly elevated total protein levels but no noted white blood cells. LP opening pressure is within normal limits. Electrocardiogram shows sinus tachycardia, with heart rate of 108 beats/minute. Chest x-ray is within normal limits.
During evaluation in the ED, the patient has a witnessed tonic-clonic seizure lasting less than 1 minute that responds immediately to phenytoin administration.
Noncontrast head computed tomography (CT) scan shows bilateral symmetric white matter edema in the posterior cerebral hemispheres, which is most prominent in the parieto-occipital regions but is not present in the calcarine and paramedian areas of the occipital lobe. T2-weighted fluid-attenuated inversion-recovery magnetic resonance imaging (MRI) shows diffuse white matter hyperintensities in the posterior cerebral hemispheres.
Labetalol drip is started and gradually titrated to lower the patient’s systolic blood pressure to 120 mm Hg as per ED protocol.
Within 3 days of admission, all symptoms have resolved completely. On day 5, repeat CT and diffusion-weight MRI scans are normal.