In the Kingdom of Triphasic Waves, White Matter Is the Eminence Grise

Triphasic waves (TWs) have been associated with multiple conditions and adverse outcomes. This study explores the role of white matter disease (WMD) in the generation of TWs when other common causes associated with these discharges are absent.

This is a retrospective case series performed at Johns Hopkins Bayview Medical Center from January 2016 to May 2018, which screened for patients with severe WMD, who had TWs on EEG without the presence of commonly cited provoking factors, including (1) hepatic disease; (2) severe uremia over baseline; (3) the drugs cefepime, ifosfamide, lithium, and baclofen; or (4) global hypoxic-ischemic injury. A control population with no WMD or abnormal electrographic findings outside of theta-delta slowing was also identified.

Eleven patients were identified. The most common comorbid condition was infection, occurring in 82% of patients. Infections were urinary tract infection (36%), respiratory (27%), and central nervous system (18%). Metabolic abnormalities included glucose aberrations (36%), calcium derangements (18%), and hypernatremia (9%). Structural abnormalities included acute stroke (9%) and chronic central nervous system abscess (9%). All except one patient had one or more structural, metabolic, or infectious abnormalities in addition to WMD. Comorbidities were not statistically different in the control population.

This is the first series to demonstrate convincingly the presence of TWs in patients with WMD in the absence of commonly cited risk factors. The authors hypothesize that less recognized risk factors of WMD and mild metabolic or infectious abnormalities may be drivers of TWs. With a growing elderly population, the presence of WMD will increase, and treating physicians need to look beyond the common causes of TWs.