Déjà Vu Episodes

Background

Déjà vu (DV, from French déjà vu — “already seen”) is an aberration of psychic activity associated with transitory erroneous perception of novel circumstances, objects, or people as already known.

Objective

This study aimed to record the EEG pattern of déjà vu.

Methods

The subjects participated in a survey concerning déjà vu characteristics and underwent ambulatory EEG monitoring (12–16 h).

Results

In patients with epilepsy, DV episodes began with polyspike activity in the right temporal lobe region and, in some cases, ended with slow-wave theta–delta activity over the right hemisphere. There were no epileptic discharges in healthy respondents during DV.

Conclusion

Two types of déjà vu are suggested to exist: “pathological-epileptic” déjà vu, characteristic of patients with epilepsy and equivalent to an epileptic seizure, and “nonpathological-nonepileptic” déjà vu, which is characteristic of healthy people and psychological phenomenon.

Keywords

• Déjà vu;
• Epilepsy;
• Ambulatory EEG monitoring

1. Introduction

Déjà vu (DV, from French déjà vu — already seen) is the term describing an aberration of psychic activity associated with transitory erroneous perception of novel circumstances, objects, or people as already known. This phenomenon belongs to the group of derealization disorders, which also includes states such as déjà vécu (already experienced), déjà entendu (already heard), and jamais vu (never seen). According to another classification, DV is a memory-based illusion . The term was coined by the French psychologist Emile Boirac (1851–1917) in his monograph L'Avenir des sciences psychiques (The Future of Psychology, 1918).

The DV phenomenon attracts special interest because, on the one hand, it occurs in most healthy individuals (up to 97% of the general population), spontaneously or in association with sleeping disorders or anxiety. On the other hand, it can be a sign of certain psychoneurological diseases, such as Charles Bonnet syndrome, temporal lobe epilepsy (TLE), depression, or schizophrenia, and it can be an early symptom of a mass lesion of the brain, , and . Thus, DV is observed both in healthy people and in patients with organic brain damage or dysfunction. Under these circumstances, it seems reasonable to identify differential diagnostic criteria to discriminate whether DV represents a normal phenomenon or a sign of a disease.

A number of modern publications are concerned with the mechanisms underlying DV and its characteristics and prevalence, , , and . We also described major clinical differential diagnostic characteristics of DV in healthy individuals , in patients with mass lesions of the brain , and in patients with epilepsy .

Déjà vu is particularly interesting as a sign of epilepsy. A DV aura occurs in 10% of patients with TLE ; DV as a sign is present in 2/3 of patients with idiopathic generalized epilepsy . In our previous paper, we also describe DV in patients with idiopathic generalized epilepsy .

Autosomal dominant temporal lobe epilepsy (ADTLE) is characterized by focal seizures with auditory symptoms or aphasia. More than 50% of patients with ADTLE have an LGI1 mutation. Recently, ADTLE cases with psychic presentations (DV and fear) but lacking classic aphasia and auditory symptoms have been described. These patients had a previously unknown LGI1 mutation, Arg407Cys, which, in contrast to the mutations described earlier, did not prevent protein secretion in vitro . To identify the brain regions involved in DV, patients with TLE with and without DV episodes were investigated using voxel-based analysis of 18FDG-PET brain scans. Patients with TLE with DV episodes exhibited unilateral focal hypometabolism in the superior temporal gyrus and the parahippocampal region, in the vicinity of the perirhinal and entorhinal cortices .

Gloor implanted electrodes on 35 patients with TLE with pharmacoresistant seizures and found that most DV episodes were associated with stimulation of the right hemisphere. Ide et al. performed a SPECT investigation in a patient with frequent DV auras and detected hyperperfusion in the right temporal and frontal lobes. Following pharmacotherapy, the frequency of seizures and DV episodes decreased, and the perfusion characteristics returned back to normal.

The main clinical problem unsolved is whether DV can be considered as a sign of epilepsy. Neppe found that DV occurred more frequently in patients with TLE (86%) than in control individuals (68%) but did not show the significance of this difference. Some other authors argue that DV can occur as a simple partial seizure, as a part of a complex partial seizure, or as an aura of a secondarily generalized tonic–clonic seizure .

Apparently, the problem cannot be solved without describing the specific ictal EEG pattern of DV, which has not been done so far to our knowledge.

The aim of the present study was to investigate the electroencephalographic characteristics of the DV phenomenon in patients with epilepsy and in healthy subjects.