Changes of EEG Coherence in Narcolepsy Measured with Computerized EEG Mapping Technique

Park, D H; Kwon, J S; Jeong, D U

Abstract

OBJECTIVES
In narcoleptic patients diagnosed with ICSD (international classification of sleep disorders, 1990) criteria, nocturnal polysomnography, and MSLT (multiple sleep latency test), we tried to find characteristic features of quantitative electroencephalography (QEEG) in a wakeful state.
METHODS
We compared eight drug-free narcolepic patients with sex- and age-matched normal controls, using computerized electroencephalographic mapping technique and spectral analysis. Absolute power,relative power, interhemispheric asymmetry, interhemispheric and intrahemispheric coherence, and mean frequency in each frequency band (delta, theta, alpha, and beta) were measured and analyzed.
RESULTS
Compared with normal controls, narcoleptic patients showed decrease in monopolar interhemispheric coherence of alpha frequency bands in occipital (O1/O2), parietal (P3/P4), and temporal (T5/T6) areas and beta frequency band in the occipital (O1/O2) area. Monopolar intrahemispheric coherences of alpha frequency bands in left hemispheric areas (T3/T5, C3/P3 & F3/O1) decreased. Decrease of monopolar interhemispheric asymmetry of delta frequency band in the occipital (O1/O2) area was also noted. The monopolar absolute powers of beta frequency bands decreased in occipital (O2, Oz) areas.
CONCLUSION
Decrease in coherences of narcoleptic patients compared with normal controls may indicate fewer posterior neo-cortical interhemispheric neuronal connections, and fewer left intrahemispheric neuronal connections than normal controls in a wakeful state. Therefore, we suggest that abnormal neurophysiological sites of narcolepsy may involve complex area such as neocortex and subcortex as well as the brainstem.