Findings suggest that compared with isolated cases, both earlier age at initial episode and a higher prevalence of personal and family history of migraine are linked to TGA recurrence.
Ken A. Morris, MD, PhD
The findings of a cohort study assessing the physiological, environmental, and other factors that increase risk for recurrence of transient global amnesia (TGA) suggest that a personal or family history of migraine may be linked to recurrent presentation of TGA compared with isolated cases.
A recurrence of TGA was linked with personal history of migraine in 20% (n = 180) of patients with a single TGA episode and 36.4% (n = 52) of those with recurrent TGA (P <.001). A family history of migraine was reported for 18.5% (n = 167) and 30.8% (n = 44) of those with single and recurrent TGA episodes, respectively.
In total, a personal and/or family history of migraine was identified 31.3% (n = 282) of individuals with a single episode of TGA and 50.3% (n = 72) of individuals with recurrent episodes of TGA (P <.001). “These findings may help clinicians when counseling patients with transient global amnesia on their risk of recurrent episodes,” the investigators concluded.
Conducted by Ken A. Morris, MD, PhD, department of neurology, Mayo Clinic, and colleagues, the study included 1044 patients with TGA. In total, at baseline, there were 901 patients with a single episode of TGA and 143 with recurrent episodes of TGA. The mean ages at inclusion were 75.1 years and 74.3 years, respectively.
“The wide range of recurrence rates [of TGA] appears to reflect the variability of the strictness of the definition of TGA, with higher rates associated with more relaxed criteria for defining TGA; and the relatively low numbers of patients with recurrent episodes, with a median of 12 patients with recurrent episodes across these studies,” they wrote. These differences in recurrence rates, they added, hamper clinical ability to discuss the likelihood of another event.
Those who had a personal history of migraine also reported an earlier mean age at TGA onset (61.1 years [standard deviation (SD), 11.3]) compared to those without (65.4 years [SD, 9.7]; P <.001). Notably, this association was present among those with single episodes of TGA (with migraine: 61.8 years [SD, 11.6]; without migraine: 66.1 years [SD, 9.4]; P <.001), but was not the case for those with recurrent TGA (with migraine: 56.8 years [SD, 12.8]; without migraine: 60.0 years [SD, 8.5]; P = .26).
Morris et al. noted that prior literature has identified migraine as a known risk factor for TGA, pointing to a similar mechanism—cortical spreading depression—operating in both cases of migraine aura and TGA.2-4 However, they wrote that “in the present study, patients with or without migraine aura had similar age at TGA onset and similar rates of TGA recurrence.”
Among the patients with a personal history of migraine, migraine aura was present in 32.8% (n = 59) of the 180 individuals with a single episode of TGA and 34.6% (n = 18) of the 52 individuals with recurrent episodes of TGA (P = .94). Those with aura had similar mean ages at TGA onset compared to those without aura for both the single episodes (with aura: 61.6 years [SD, 11.4]; without aura: 61.9 years [SD, 11.7]; P = .87) and recurrent episodes (with aura: 56.3 years [SD, 15.0]; without aura: 57.1 years [SD, 11.7]; P = .83).
“TGA is considered a benign event that is unlikely to recur. Studies suggest that TGA is not associated with an increased risk for development of other neurologic disorders, such as stroke, dementia, or epilepsy,” Morris et al. wrote. “Nonetheless, TGA can be emotionally distressing for both patients and family members, and can mimic neurologic emergencies such as stroke or seizures. It may also have implications for certain occupations. Therefore, it is important for clinicians to be able to counsel patients on their risk of TGA recurrence, including any factors that may increase the likelihood of another event.”