Reliability of Upper Limb Pin-Prick Stimulation With Electroencephalography: Evoked Potentials, Spectra and Source Localization

Abstract

In order for electroencephalography (EEG) with sensory stimuli measures to be used in research and neurological clinical practice, demonstration of reliability is needed. However, this is rarely examined. Here we studied the test-retest reliability of the EEG latency and amplitude of evoked potentials and spectra as well as identifying the sources during pin-prick stimulation. We recorded EEG in 23 healthy older adults who underwent a protocol of pin-prick stimulation on the dominant and non-dominant hand. EEG was recorded in a second session with rest intervals of 1 week. For EEG electrodes Fz, Cz, and Pz peak amplitude, latency and frequency spectra for pin-prick evoked potentials was determined and test-retest reliability was assessed. Substantial reliability ICC scores (0.76–0.79) were identified for evoked potential negative-positive amplitude from the left hand at C4 channel and positive peak latency when stimulating the right hand at Cz channel. Frequency spectra showed consistent increase of low-frequency band activity (< 5 Hz) and also in theta and alpha bands in first 0.25 s. Almost perfect reliability scores were found for activity at both low-frequency and theta bands (ICC scores: 0.81–0.98). Sources were identified in the primary somatosensory and motor cortices in relation to the positive peak using s-LORETA analysis. Measuring the frequency response from the pin-prick evoked potentials may allow the reliable assessment of central somatosensory impairment in the clinical setting.

EEG Responses to Upper Limb Pinprick Stimulation in Acute and Early Subacute Motor and Sensorimotor Stroke

“…In contrast to median nerve stimulation and passive movements, pinprick stimulation yields the advantages of being a pure somatosensory stimulus that is easy to combine with EEG, and well-controlled in terms of stimulus intensity (24)(25)(26). Indeed, our recent work in healthy controls highlights that pinprick stimuli on the dorsa of the hands are highly reliable to explore oscillatory activity in the delta, theta and alpha frequency bands in first 0.25s (27). Concerning pinprick SEP amplitude analyses, we hypothesised that people with acute stroke to have longer latencies and reduced amplitudes which will correlate with the severity of somatosensory and motor deficits (18,23).…”

“…In contrast to median nerve stimulation and passive movements, pinprick stimulation yields the advantages of being a pure somatosensory stimulus that is easy to combine with EEG, and well-controlled in terms of stimulus intensity (24-26). Indeed, our recent work in healthy controls highlights that pinprick stimuli on the dorsa of the hands are highly reliable to explore oscillatory activity in the delta, theta and alpha frequency bands in first 0.25s (27).…”

“…vision of participants in relation to the tested hand was blocked by means of a screen.Pinprick application was performed in a standardized manner(27) In both hands, the distance between the base of metacarpal I to the middle of metacarpal V was measured. The middle of this distance served as the centre of a circle drawn on the dorsum of the hand.…”