In an effort to better comprehend the causes of juvenile stroke, a German doctor and his team conducted an exhaustive investigation into the etiology of the disease in patients between 18 and 55 years old.

Florian Schöberl and the coauthors of a study published in the journal Deutsches Ärzteblatt this month used PubMed literature ranging from the 1990s through present day to delve into the reasons behind stroke in individuals under 55 years old. Reviews, randomized controlled studies, meta-analyses, cohort studies, case-control studies and case reports were all used in an effort to better understand the phenomenon.

Juvenile stroke makes up about 15 percent of all stroke cases in Germany, according to Schöberl’s study—around 30,000 cases per year. However, since stroke largely affects an older demographic, much is still unknown about the etiology and treatment of the disease in patients under 55 years old. While 2.4 in 100,000 citizens aged 20 to 24 will suffer a juvenile stroke, according to Schöberl’s research, that number jumps to 1,200 per 100,000 people between 75 and 84 years old.

By far, the most common type of juvenile stroke is arterial ischemic stroke, comprising an average of 70 percent of all cases, Schöberl and co-authors wrote. Other classifications include intracerebral hemorrhage, subarachnoid hemorrhage and cerebral venous sinus thrombosis.

According to Schöberl’s findings, spontaneous cervical artery dissections, though generally rare, are one of the more common causes of young adult stroke (juvenile stroke in patients between 18 and 39 years old), presenting themselves in 10 to 25 percent of juvenile cases. Five to 25 percent of young adult strokes are thought to be caused by cardiac embolism, and genetic predisposition, environmental factors, traumas and infections were observed to be contributing factors. Common symptoms of juvenile stroke include headaches, sore throat, Horner’s syndrome and cerebrospinal nerve disruption.

One of the most prevalent causes of stroke in the elderly is atrial fibrillation (AF), according to Schöberl’s study, and doctors recommend screening for AF in young adult stroke patients. However, while AF makes up 25 to 35 percent of stroke cases in older patients, it’s a rare cause in young adult cases, composing just 5 percent.

As patients get older, cardiovascular risk factors, as well as risk of stroke, increases, Schöberl and his co-authors wrote. Arterial hypertension, cigarette smoking, fat metabolism disorders and diabetes mellitus also increase with age, and adults who suffer from stroke earlier in their lives are more likely to suffer from macro- and microangiopathy after they turn 40.

Rare and very rare causes make up at least 10 percent of all juvenile stroke cases, according to the study. Pregnancy, especially late-term pregnancy and post-birth, is a factor that can increase the likelihood of stroke, Schöberl wrote, as well as migraines. Migraines, especially those with aura, can increase stroke risk by a factor of two, notably in women under 55 years old. The chance of stroke appears to increase with the frequency of migraines.

Oral contraceptives that contain estrogen, if taken by women suffering from additional risk factors, could be dangerous, according to the study, though the effect oral contraceptives and hormone replacement therapy have on stroke risk is still unclear. Illicit drugs—especially intravenous substance abuse—also raise risk.

Schöberl and his colleagues reported up to 50 percent of all strokes in young adults have no definitive cause. The one-year mortality rate for young adult stroke is 4.5 percent, they wrote, with a one-year recurrence rate of just 1.5 percent. This is extremely low compared to strokes in older adults; the one-year mortality rate for that demographic is 15 to 35 percent with a one-year recurrence rate of 2 to 15 percent.

The functional outcome of younger patients is also more positive than results in elderly individuals, though 33 percent of young adult stroke sufferers are permanently unable to work. While 40 percent of those patients return to their jobs, 27 percent are forced to change their workplace to accommodate medical restrictions.

“The high rates of cryptogenic stroke and ESUS (embolic stroke of undetermined source) among patients with juvenile stroke indicate that uncertainties remain in the diagnosis and treatment of this entity,” Schöberl and co-authors wrote. “The identification of rare causes of juvenile stroke requires a major diagnostic effort.”