Clinical correlates of phosphene perception in migraine without aura: An Asian study

Cortical inhibition and habituation to evoked potentials: relevance for pathophysiology of migraine

“…According to this view, more recently, Lo et al (2008) found lower prevalence of phosphenes in migraine patients showing a worse clinical picture [36]. …”

Postmodernism, Neuroscience and the Brain

“…Whether the cortex itself is hyperexcitable or hypoexcitable has become a contentious issue in migraine research 11 , to the extent that workers in this field have become academically divided. However, recent evidence has emerged to suggest that the migrainous brain has toggled between the two states in a temporal fashion, which may be a result of a propagating inbuilt homeostatic capability 12 . It would, therefore, be simplistic and erroneous if researchers had stubbornly pursued dichotomous directions without considering what lies in between, simply by clinging onto dogma.…”

Does the menstrual cycle influence the motor and phosphene thresholds in migraine?

“…These studies are in conflict with data on the lower prevalence of phosphenes in MA patients when compared with healthy controls [6] or the same prevalence but increased PTs, suggesting a decreased excitability of the visual areas [7]. Recently, an Asian study showed that migraine patients without aura (MO) had reduced interictal visual cortex excitability in relation to the severity of migraine [8]. Furthermore, no differences between migraineurs and controls with regard to PTs were reported [9].…”

“…As most of the migraineurs are female patients, there is a possibility that the contradictory results published in the above‐mentioned studies are due to the different measurements made over various time points in different phases of the menstrual cycle. Therefore we measured the effects of ovarian hormones on TMS threshold measures, as (i) studies investigating migraineurs and normal women found altered motor excitability and PTs in migraineurs [2–9,11–20], (ii) motor threshold seems not to be influenced by ovarian hormones in normal women [22,23,28] but there exists no data with regard to migraineurs. We evaluated the variability of interictal PTs and RMTs over time (minimum of three, maximum of six measurements during the menstrual cycle) of migraine patients.…”