Visual and vestibular functioning, and age and surgery effects on postural control in healthy children with vertical strabismus.

Purpose: To describe visual and vestibular functioning and the effects of age and surgery effects on postural control in healthy children with vertical strabismus.

Design: This is a comparative case series.

Methods: We evaluated participants at the Scientific Institute Eugenio Medea during routine clinical activities.

High frequency oscillations after median nerve stimulations in healthy children and adolescents.

The aim of the present research was to address somatosensory high frequency oscillations (400-800Hz) in healthy children and adolescents in comparison with healthy adults. We recorded somatosensory evoked potentials following median nerve stimulation in nineteen resting healthy children/adolescents and in nineteen resting healthy adults with eyes closed. We administered six consecutive stimulation blocks (500 sweeps each).

Cortical hyper-excitability in healthy children: evidence from habituation and recovery cycle phenomena of somatosensory evoked potentials.

Aim: To compare neurophysiological parameters of central nervous system excitability in healthy children/adolescents with those of healthy adults.

Method: Two experimental protocols were used in 19 healthy children/adolescents (10 males and 9 females, mean age 9y 11mo [SD 2y 9mo], range 5-15y) and 19 healthy adults (8 males and 11 females, mean age 36y 6mo [SD 7y 9mo], range 27-51y). First, we administered repetitive trains of innocuous electrical stimulation of the median nerve and analysed habituation (progressive attenuation) of the cervical and cortical responses.

Patterns of habituation and clinical fluctuations in migraine.

Background: Habituation deficit, suggesting a deregulation of cortical excitability, represents a typical hallmark of interictal stages of migraine. We previously demonstrated that several neurophysiological markers of altered cortical excitability are significantly correlated to spontaneous clinical fluctuations of migraine. We therefore aimed at verifying whether clinical fluctuations are correlated to specific patterns of somatosensory evoked potential (SEP) habituation.

Different levels of cortical excitability reflect clinical fluctuations in migraine.

Background: In a previous study we demonstrated that high-frequency oscillations (HFOs) elicited by median nerve stimulation are significantly correlated to clinical fluctuations of migraine. We aimed at verifying whether clinical fluctuations and HFO changes are correlated to N20 somatosensory evoked potential (SEP) recovery cycle, which is likely to reflect the functional refractoriness of primary somatosensory cortex neurons.

Methods: We analysed both HFOs and N20 SEP recovery cycle to paired stimulation in 21 migraine patients and 18 healthy volunteers.

Somatosensory High Frequency Oscillations reflect clinical fluctuations in migraine.

Objective: It has been demonstrated that the early part of 600 Hz High Frequency Oscillations (HFOs), probably generated in the terminal part of thalamo-cortical somatosensory radiations, are abnormally reduced between attacks in migraineurs. We aimed at verifying whether spontaneous clinical fluctuations in migraine are correlated to HFO changes.

Methods: We recorded somatosensory evoked potentials in 28 migraine patients.

High-frequency oscillations after median-nerve stimulation do not undergo habituation: a new insight on their functional meaning?

Objective: Amplitude decrease of cortical responses after repeated stimuli ('habituation') is a well-known phenomenon, the functional meaning of which is to prevent sensory overflow and to save resources for meaningful and novel stimuli. It is known that the primary low-frequency N20 somatosensory evoked potential (SEP) undergoes habituation in healthy subjects. By contrast, the presence of this phenomenon has never been tested in High Frequency Oscillations (HFOs), which probably reflect the activity of a somatosensory arousal system.

Somatosensory mismatch negativity in healthy children.

Aim: Event-related potentials (ERPs) obtained when focused attention is kept away from the stimulus (unnoticed stimulation) are possibly linked to automatic mismatch-detection mechanisms, and could be a useful tool to investigate sensory discrimination ability. By considering the high impact of impaired somatosensory integration on many neurological disturbances in children, we aimed to verify whether mismatch-related responses to somatosensory stimulation could be obtained in healthy children.

Method: Eleven healthy participants (age range 6-11y, mean 8y 2mo, SD 1y 7mo; seven males, four females) underwent 'oddball' electrical stimulation of the right hand (80% frequent stimuli delivered to the thumb, 20% deviant stimuli delivered to the fifth finger).

Dissociated effects of quiet stance on standard and high-frequency (600 Hz) lower limb somatosensory evoked potentials.

Objective: To verify whether standing can modulate somatosensory input from lower limb to the cortex. Somatosensory afferents have been evaluated not only by means of somatosensory evoked potentials recorded by means of classical wide-bandpass filtering (standard SEPs), but also by high-frequency somatosensory evoked potentials (HF-SEPs), which probably play a role in the processing of rapid adaptive changes.

Methods: Eight healthy subjects underwent right posterior tibial nerve (PTN) stimulation in two different conditions (standing and lying supine).