ALTERED FUNCTIONAL MAGNETIC RESONANCE IMAGING RESTING-STATE CONNECTIVITY IN PERIAQUEDUCTAL

GRAY NETWORKS IN MIGRAINE

Kevin Bach

Caterina Mainero, Jasmine Boshyan, and Nouchine Hadjikhani

Overview

Introduction Hypothesis Methods Results Discussion Strengths & Limitations Personal Opinion

What is a migraine?

A common type of headache Additional symptoms:

NauseaVomitingSensitivity to lightSensitivity to sound

Pain is usually felt only on one side of the head

Introduction

Current concepts of migraine: neurological disorderBroad sensory processing dysfunction

Periaqueductal Gray Matter (PAG)Key area for migraineKnown modulator of somatic pain Subjects without headaches developed migraine-like

episodes after electrode placement in PAGAbnormalities in the PAG of migraineurs often paralleled

by structural changes in connected brain regions involved in pain processing and modulation

Introduction

Prevailing theory in the cause of the migraine attack:Hyperexciatability along neurons in the trigeminal

nerve that innervate cerebral blood vessels○ Facilitated by dysfunction of the pain modulatory

circuits Previous studies show hypofunction of pain

modulatory circuits during the interictal phase of migraineMight contribute to the development of the migraine

attack

Hypothesis

1) Intrinsic connectivity within the PAG and somatosensory/pain processing and modulatory pathways would be dysfunctional in migraineurs relative to age-matched healthy subjects

2) These alterations would be associated with disease severity as measured by the frequency of migraine attacks per month

Methods

Resting-state fMRI 17 patients with episodic migraine

15 females2 males32.4 ± 8.2 years oldAll patients migraine free for at least 72 hoursMigraines per Month

17 gender- and age-matched healthy subjects No history of migraine or other headache types

Results

Both groups showed predominantly positive correlations between PAG and cortical regions involved in pain and somatosensory processing

Correlations more prevalent in migraineurs Higher the migraine frequency

Greater connectivity between the PAG and the hypothalamus, anterior insula, brainstem

Lower connectivity between the PAG and the prefrontal cortex, anterior cingulate, amygdala

Discussion Interictal increase in resting-state connectivity between

the PAG and both nociceptive and sensory processing pathways in migraineurs compared to controls Could reflect a hyperexcitability of pain pathways

The greater the number of migraine attacks per month: Stronger connectivity between the PAG and both nociceptive

and sensory processing pathways Weaker connection between the PAG and brain regions with a

role in pain modulation

Discussion PAG is known to regulate the brainstem pain-inhibiting

circuitry

Prefrontal cortex controls functional interactions among nociceptive brain regions to modify perceptual correlates of pain through pain-inhibitory mechanisms Reduced connectivity between PAG and prefrontal cortex

correlated with the increase in migraine attack frequency

Development of migraines may be a result of an interictal dysfunction of the inhibitory system

Strengths, Limitations & Future Studies

Looked at the relation between migraine severity and the degree of dysfunction within PAG networks

Resting brain activity is either increased or decreased in other chronic pain conditionsFuture studies may clarify whether observed

changes are a signature of migraines or are shared by other chronic pain conditions

My opinion

Slightly difficult to understandMany brain areas involvedNot much known about migraines & pain

pathways Pleased to see progress in the understanding

of migraines

Thank you