Monozygotic twin sisters discordant for familial hemiplegic migraine

A Retrospective, Epidemiological Review of Hemiplegic Migraines in a Military Population

INTRODUCTION

Headaches are one of the world's most common disabling conditions. They are also both highly prevalent and debilitating among military personnel and can have a significant impact on fitness for duty. Hemiplegic migraines are an uncommon, yet severely incapacitating, subtype of migraine with aura for which there has been a significant increase amongst US military personnel over the past decade. To date, there has not been a scientific report on hemiplegic migraine in United States military personnel.

MATERIALS AND METHODS

The aim of this study was to provide an overview of hemiplegic migraine, to analyze data on the incidence of hemiplegic migraine in US military service members, and to evaluate demographic factors associated with hemiplegic migraine diagnoses. First time diagnoses of hemiplegic migraine were extracted from the Defense Medical Epidemiological Database according to ICD-9 and ICD-10 codes for hemiplegic migraine. One sample Chi-Square goodness of fit tests were conducted on weighted demographic samples to determine whether significant proportional differences existed between gender, age, military grade, service component, race, and marital status.

RESULTS

From 1997 to 2007 there were no cases of hemiplegic migraine recorded in the Defense Medical Epidemiological Database. However, from 2008 to 2017 there was a significant increase in the number of initial diagnoses of hemiplegic migraine, from 4 in 2008 to a high of 101 in 2016. From 2008 to 2017, 597 new cases of hemiplegic migraine were reported among US military service members. Disproportional incidence of hemiplegic migraine was observed for gender, X2 (1, 597) = 297.37, p <.001, age, X2 (5, 597) = 62.60, p <.001, service component, X2 (3, 597) = 31.48, p <.001, pay grade X2 (3, 597) = 57.96, p <.001, and race, X2 (2, 597) = 37.32, p <.001, but not for marital status X2 (1, 597) = 2.57, p >.05.

CONCLUSION

Over the past decade, there has been a significant increase in the number of initial diagnoses of hemiplegic migraine in Active Duty United States military personnel. Based on these diagnosis rates, there is evidence to suggest that hemiplegic migraine has a higher incidence and prevalence rate among post 9/11 service members of the United States military as compared to the general population. Given the sudden increase in new patients diagnosed with hemiplegic migraine in the past decade, the global prevalence estimates of hemiplegic migraine should be reconsidered. Additionally, the impact of hemiplegic migraine on service member's duties and responsibilities deserves further consideration.

Genetics of Migraine: Insights into the Molecular Basis of Migraine Disorders

Migraine is a complex, debilitating neurovascular disorder, typically characterized by recurring, incapacitating attacks of severe headache often accompanied by nausea and neurological disturbances. It has a strong genetic basis demonstrated by rare migraine disorders caused by mutations in single genes (monogenic), as well as familial clustering of common migraine which is associated with polymorphisms in many genes (polygenic). Hemiplegic migraine is a dominantly inherited, severe form of migraine with associated motor weakness. Family studies have found that mutations in three different ion channels genes, CACNA1A, ATP1A2, and SCN1A can be causal. Functional studies of these mutations has shown that they can result in defective regulation of glutamatergic neurotransmission and the excitatory/inhibitory balance in the brain, which lowers the threshold for cortical spreading depression, a wave of cortical depolarization thought to be involved in headache initiation mechanisms. Other putative genes for monogenic migraine include KCKN18, PRRT2, and CSNK1D, which can also be involved with other disorders. There are a number of primarily vascular disorders caused by mutations in single genes, which are often accompanied by migraine symptoms. Mutations in NOTCH3 causes cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a hereditary cerebrovascular disease that leads to ischemic strokes and dementia, but in which migraine is often present, sometimes long before the onset of other symptoms. Mutations in the TREX1 and COL4A1 also cause vascular disorders, but often feature migraine. With respect to common polygenic migraine, genome-wide association studies have now identified single nucleotide polymorphisms at 38 loci significantly associated with migraine risk. Functions assigned to the genes in proximity to these loci suggest that both neuronal and vascular pathways also contribute to the pathophysiology of common migraine. Further studies are required to fully understand these findings and translate them into treatment options for migraine patients.