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

Hemiplegic Migraine

PURPOSE OF REVIEW

In this article, we review recent updates to the epidemiology, diagnostic testing, genetics, pathophysiology, and management of hemiplegic migraine.

RECENT FINDINGS

While three genes have been historically associated with hemiplegic migraine, recent studies suggest two additional genes may also be implicated including PPRT2 and SLC1A3. Hemiplegic migraine is a severe subset of migraine with aura with symptoms including reversible hemiparesis in addition to other aura symptoms such as visual, sensory, or speech. The exact pathophysiology of hemiplegic migraine is not clear, but it is thought that this phenomenon is due to neuronal and glial depolarization causing cortical spreading depression. Due to the severity of presentation as well as the numerous mimickers, it is important to know a comprehensive differential and work-up. Given the low prevalence of the disease, most studies regarding treatment are limited to case studies. There is still an important need for further and larger studies regarding management of these cases.

Genetics of migraine: where are we now?

Migraine is a complex brain disorder explained by the interaction of genetic and environmental factors. In monogenic migraines, including familial hemiplegic migraine and migraine with aura associated with hereditary small-vessel disorders, the identified genes code for proteins expressed in neurons, glial cells, or vessels, all of which increase susceptibility to cortical spreading depression. The study of monogenic migraines has shown that the neurovascular unit plays a prominent role in migraine. Genome-wide association studies have identified numerous susceptibility variants that each result in only a small increase in overall migraine risk. The more than 180 known variants belong to several complex networks of "pro-migraine" molecular abnormalities, which are mainly neuronal or vascular. Genetics has also highlighted the importance of shared genetic factors between migraine and its major co-morbidities, including depression and high blood pressure. Further studies are still needed to map all of the susceptibility loci for migraine and then to understand how these genomic variants lead to migraine cell phenotypes.

Sex comparisons in physiological and cognitive performance during hypoxic challenge

Within the tactical aviation community, human performance research lags in considering potential psychophysiological differences between male and female aviators due to little inclusion of females during the design and development of aircraft systems. A poor understanding of how male and female aviators differ with respect to human performance results in unknown potential sex differences on aeromedically relevant environmental stressors, perchance leading to suboptimal performance, safety, and health guidelines. For example, previous hypoxia studies have excluded female participants or lacked a sizeable sample to examine sex comparisons. As such, progress toward sensor development and improving hypoxia familiarization training are stunted due to limited knowledge of how individual differences, including sex, may or may not underlie hypoxia symptoms and performance impairment. Investigating sex differences bridges the gap between aerospace medicine and operational health, and addressing hypoxia is one of many facets yet to be studied. In the current study, we retrospectively examined N = 6 hypoxia studies with male-female participant samples (total, N = 189; male, n = 118; female, n = 71). We explored sex as a predictor of physiological response, sensory deficits, the severity of cognitive performance declines, and symptom manifestation via linear and binary logistic regression models. We found that the female sex predicted lower peripheral oxygen saturation and the likelihood of headache reporting in response to hypoxic challenge, yet explained little variance when combined with age and body mass index. The sensory and cognitive performance models did not converge, suggesting high intra-individual variability. Together, sex, age, and body mass index were not the most robust predictors in responses to hypoxic challenge; we cannot infer this for sensory deficits and cognitive performance within an experimentally induced hypoxic environment. The findings have implications for improving hypoxia familiarization training, monitoring sensor development, and emergency response and recovery protocols in case of a hypoxia occurrence suitable for all aircrew. We recommend continuing to elucidate the impact of sex and intrapersonal differences in hypoxia and other aeromedically relevant stressors in tactical aviation.

Incidence (2008-2015) of post-traumatic headaches in United States military personnel

Objective: To conduct a descriptive transversal study to evaluate the incidence and demographic characteristics of post-traumatic headache using data from the Defense Medical Epidemiology Database.Methods: A retrospective cohort study was conducted of data from 2008 to 2015 based on the International Classification of Diseases codes for both acute and chronic post-traumatic headache.Results: A total of 17,010 new cases of post-traumatic headaches were diagnosed among active duty military personnel. Reported incidence rates of post-traumatic headaches in the military increased 29-fold over the timeframe analyzed. Males enlisted in the Army were more likely to be diagnosed with post-traumatic headaches than females (O/E = 0.76), other branches, and officers.Conclusion: Findings of this study indicate that there is a significant incidence of post-traumatic headaches in the U.S. military. However, the incidence rates of post-traumatic headaches in the military are much lower than what was expected considering the number of traumatic brain injuries in the United States military reported by the Department of Defense for the same period. Additional research is needed to further evaluate these differences and the impact of PTHs on military personnel.

Incidence Rates of Tinnitus in Active Duty Military Service Members Between 2001 and 2015

Purpose Due to hazards in the contemporary operating environment, U.S. military service members are at increased risk for tinnitus. Previous research has characterized tinnitus prevalence in military veterans, but no population-based study of tinnitus has been conducted in active duty military service members. This study evaluated the incidence of tinnitus diagnoses in military electronic health records based on International Classification of Diseases, 9th Revision (ICD-9) codes for active duty service members between 2001 and 2015. Method Data on 85,438 active duty military service members who served between 2001 and 2015 were drawn from the Defense Medical Epidemiological Database and stratified by race, age, sex, marital status, service branch, and military pay grade. Results The incidence rate of tinnitus in U.S. military service members (per 1,000) rose consistently from 1.84 in 2001 to 6.33 in 2015. Service members most often diagnosed with tinnitus were White (72%), married (72%), males (88%), in the enlisted pay grade of E-5 to E-9 (55%), in the Army (37%), and were 35 years of age or older (50%). Statistically significant differences (p < .001) were found between observed and expected counts across all 6 demographic variables. Conclusions This is the first study to assess the incidence rates of tinnitus in active duty service members. Although there are many risk factors for auditory damage in the contemporary military operating environment, the extant literature on tinnitus in active duty military service members is limited. Future studies should consider the relationship between tinnitus-related psychological comorbidity and objective health-related quality of life, as it impacts operational readiness in active duty military service members.

White Matter Hyperintensities in Patients with Sporadic Hemiplegic Migraine

BACKGROUND AND PURPOSE

To identify the differences in overall occurrence, location, and disease burden of white matter hyperintensities (WMH) in patients with sporadic hemiplegic migraine (SHM) and patients with migraine headaches.

METHODS

We included patients who met diagnostic criteria proposed by the third International Classification of Headache Disorders (ICHD-3) for SHM and migraine headache. WMHs were identified using T2 fluid-attenuated inversion recovery axial sequence and classified based upon the location. The disease burden was assessed using Scheltens visual rating scale.

RESULTS

Fifty patients met the diagnostic criteria for SHM and 100 patients for migraine headache. Patients in the study group were similar to the control group in terms of age (47.7 ± 12.2 years vs. 48.17 ± 9.7 years; P = .814) and gender (M: F; 14:36 vs. M: F 25:75; P = .693). WMH were found in 28 (56%) patients with SHM and 44 (44%) in patients with migraine headache. The proportion of patients with WMH was not different between the two groups (P = .166). On univariate analysis, the proportion of patients with WMH in parietal, occipital, and infratentorial regions was higher in patients with SHM. White matter burden determined by visual rating scale and proportion of patients with lesions ≥5 mm in diameter was also significantly higher in patients with SHM. On multivariate analysis, the WMH occurrence in the parietal lobe (P = .043) was found to be significantly higher in SHM.

CONCLUSIONS

The WMH occurrence in patients with SHM is significantly more in the parietal lobe when compared to those with migraine headaches. WMH burden was also higher in patients with SHM, and larger white matter lesions occurred more frequently in these patients with SHM (compared to ordinary migraineurs).