Bilateral prefrontal hypermetabolism in FDG-PET – a functional correlate of delirium tremens?

Introduction: Delirium tremens is a complication frequently seen in patients during alcohol withdrawal. Little is known about the functional changes that occur in the brains of patients during states of delirium tremens.

Case report: We report a 77 year old woman who was admitted to the emergency room with a state of reduced consciousness and intermittent agitation of unknown etiology. The patient lived alone and no additional information about the previous history and manifestation of the reduced state of consciousness was available at that time. Neurological exam revealed no other deficits. Blood tests were normal. Screening for alcohol, barbiturates, benzodiazepines, and cocaine were negative in urine and blood. There was no sign for infection in the blood tests and the axilar and anal temperature were within normal range. CSF was normal. EEG showed slightly abnormal background activity with intermittent theta-waves bifrontally but no epileptic potentials. CT, CT-angiography, MRI, and MRI-angiography of the brain were normal. FDG-PET scan of the brain revealed highly significant bilateral prefrontal hypermetabolism. Repeat EEGs again revealed no epileptic potentials. The patient recovered within a few days. A follow-up FDG-PET after recovery of normal conciousness showed normal brain metabolism. The patient then admitted consumption of larger quantities of alcoholic beverages until a few days before admission. Delirium tremens was diagnosed and thought to be responsible for the altered conciousness (figure 1: FDG-PET of patient during and after delirium tremens, figure 2: statistical comparison of patient with control group).

Conclusion: We conclude that states of dilirium tremens may be associated with increased bilateral prefrontal brain activity. To the best of our knowledge this is the first functional brain imaging of a patient during delirium tremens. Hypometabolism was observed in FDG-PETs of the orbitofrontal cortices of patients with chronic alcohol abuse after several weeks to months of abstinence (Dao-Castellana et al. 1998). However, in a recent study with social drinkers fMRI performed within 24 hours of abstinence revealed an orbitofrontal cortex activation during this early phase of abstinence (Myrick et al 2004). The activation was positively correlated with the severity of craving. Thus delirium tremens may be seen as a very severe form of craving with associated frontal hypermetabolism.