Quantitative EEG Markers of Elevated Intracranial Pressure in a Case of Carcinomatous Meningitis

We present the case of a 69-year-old woman with acute myeloid leukemia with recurrent transient events characterized by loss of awareness and generalized shaking. The events were initially diagnosed as seizures based on semiology but persisted despite antiseizure medications. The events were recorded using continuous video electroencephalography (EEG) with no epileptiform correlate. However, pertinent changes included diffuse attenuation of fast activity, increase in delta activity, and subsequent attenuation of faster frequencies. Quantitative EEG detected a decrease in fast activity, alpha-delta ratio, and amplitude-integrated EEG. The transient events and EEG findings in the setting of known cancer history raised concern for carcinomatous meningitis despite unremarkable brain imaging. Lumbar puncture showed an elevated opening pressure and cytology confirmed a myeloid blast population consistent with acute myeloid leukemia. The events resolved with serial lumbar punctures supporting the fact that the events were likely secondary to transient elevations in intracerebral pressure. In summary, video EEG with quantitative EEG analysis is a sensitive, non-invasive way to confirm transient elevated intracranial pressure and rule out epileptic activity. This constellation of cancer, clinical symptoms and EEG findings should increase suspicion of carcinomatous meningitis.