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Bilateral centrotemporal spikes triggered by blinking: an unusual form of sensory input with related cortical EEG
R Vetrugno1, S Meletti, G Plazzi
1Institute of Clinical Neurology, University of Bologna, Italy. liguori@neuro.unibo.it
Insights
Blink-related spikes (BRS) and spontaneous spikes (SS) share similar EEG morphology and temporal characteristics. Blinking, both involuntary and reflex, may activate similar trigeminal pathways, generating these EEG abnormalities.
Area of Science:
- Neurophysiology
- Epileptology
- Clinical Neurophysiology
Background:
- Investigating the origin and characteristics of electroencephalogram (EEG) abnormalities is crucial for understanding neurological disorders.
- Blink-related spikes (BRS) are EEG phenomena associated with eye movements, but their precise generation mechanisms and relationship with spontaneous spikes (SS) require further elucidation.
Observation:
- A 7-year-old boy with chromosomopathy and mild intellectual disability presented with left spontaneous centrotemporal spikes (SS) and bilateral blink-related spikes (BRS).
- Video-polygraphic recordings revealed that SS and BRS exhibited identical four-peak morphology (P1, N1, P2, N2).
- BRS were consistently observed following orbicularis oculi muscle contraction, with overlapping peak latencies on bilateral centrotemporoparietal electrodes, and reflex blinking also elicited similar waveforms.
Findings:
- Spontaneous spikes (SS) localized to left centroparietal regions, while bilateral blink-related spikes (BRS) were found in centrotemporoparietal areas.
- The temporal relationship between BRS and orbicularis oculi contraction was clearly defined, with consistent peak latencies.
- Reflex blinking, induced by glabellar tapping, generated waveforms with morphology and temporal features akin to BRS.
Implications:
- The trigeminal system, through sensory stimulation from both involuntary and reflex blinking, likely engages common neural pathways and cortical sources for generating EEG abnormalities.
- These findings suggest a potential link between blinking activity and the generation of specific EEG patterns, offering insights into neurophysiological mechanisms in individuals with developmental and neurological conditions.
- Understanding these relationships may aid in the diagnosis and management of epilepsy and other neurological disorders characterized by EEG abnormalities.
Objective:
To investigate the morphology, scalp topography and temporal relationship with orbicularis oculi muscle contraction of bilateral blink related spikes (BRS) in a 7-year-old boy with chromosomopathy, mild mental retardation and left spontaneous centrotemporal spikes (SS).
Methods:
The patient underwent video-polygraphic recordings with off-line analysis of SS and BRS by means of spike-averaging and orbicularis oculi contraction-locked averaging techniques respectively. EEG activity related to reflex blinking (evoked by glabellar tapping) was also studied.
Results:
SS and BRS presented the same morphology, characterised by four peaks (P1, N1, P2, N2). SS were located over the left centroparietal regions, while BRS were placed over both left and right centrotemporoparietal regions and constantly followed the contraction of orbicularis oculi with overlapping peak latencies over C3 and C4 electrodes (P1 72 ms; N1 115 ms; P2 164 ms; N2 236 ms). Reflex blinking evoked a small waveform with the same features as BRS.
Conclusions:
Our findings suggest that both involuntary and reflex blinking can act as a form of sensory stimulation probably engaging similar nervous pathways and cortical sources in generating EEG abnormalities: the trigeminal system.