Investigate paroxysmal symptoms in Dementia with Lewy bodies (DLB) and corresponding EEG correlates.

DLB diagnostic criteria have multiple paroxysmal features  - variation in attention and alertness, well-formed visual hallucinations, syncope, and REM sleep behavior disorder (RBD), whose pathophysiology is unclear. Epileptic origin is considered one of the possibilities. Few studies have systematically looked at EEG features of DLB patients in relation to these symptoms. One study of EEG in autopsy-confirmed  DLB showed focal temporal lobe slowing in half the patients (7/14).  These had a statistically higher likelihood of having syncope. Another study found that 15% of patients with DLB will have seizures.

We found 24 patients with probable DLB, eleven of whom had EEGs. Eight of these suffered from visual hallucinations with six having generalized slowing and one left occipital slowing on EEG. Six patients had an alteration in attention with five patients having generalized slowing and one having left occipital slowing. All three RBD patients had generalized slowing on EEG. Two out of four syncope patients had diffuse slowing while two were normal.  Two patients (8.3%) had seizures, one with normal EEG and another with left occipital slowing. Overall, two EEGs were normal, eight showed generalized slowing, one focal left occipital slowing but none had epileptiform discharges. Fisher’s exact square test did not yield a significant relationship between abnormal EEG findings and visual hallucinations (p=0.15) or fluctuation in attention (p=0.18).

In this small retrospective study, paroxysmal symptoms of DLB were not associated with specific interictal EEG abnormalities, but further study is needed to evaluate ictal EEG correlates and analyze with quantitative EEG.