Juvenile Ischaemic Stroke: Why Young Patients Require a Different Diagnostic Mindset

Ischaemic stroke is typically considered a disease of older age. Yet approximately 10% of strokes occur in adults between 18 and 55 years [1]. While acute management in these patients largely follows the same principles as in older individuals, determining the underlying cause often presents a much greater challenge.

In contrast to older patients, where vascular risk factors such as hypertension, diabetes, or atherosclerosis frequently explain the event, stroke in younger adults is far more likely to result from uncommon or non-classical mechanisms [2]. This difference has direct clinical implications. In many young patients, the traditional diagnostic framework fails to identify the cause of stroke.

 

The usual suspects in young stroke

Cardioembolism represents one of the leading mechanisms of stroke in younger adults. While atrial fibrillation is the most common source of cardioembolic stroke in older populations, it accounts for only a small proportion of strokes in younger patients. Instead, a patent foramen ovale is often the most relevant cardiac finding. Approximately 50% of patients aged 60 years or younger with an embolic stroke of undetermined source have a PFO, compared with 25% of the general population. It has been estimated that approximately 10% of all ischaemic strokes in young and middle-aged adults can be attributed to paradoxical embolism through a PFO [3].

The second most common mechanism is cervical artery dissection, which accounts for up to 15–25% of strokes in adults under 50 years of age. Dissections of the carotid or vertebral arteries often occur spontaneously and may initially present with relatively subtle symptoms such as unilateral neck pain or headache [4].

Beyond conventional vascular risk factors and cardiac sources of embolism, clinicians must also consider prothrombotic disorders in young stroke patients. Antiphospholipid syndrome (APS) represents one of the most clearly established risk factors for arterial thrombotic events in younger individuals [5]. In contrast, the contribution of inherited thrombophilias, such as factor V-mutations, to arterial stroke risk remains controversial and routine testing is generally not advised [6]. However, the clinical relevance may be greater in the presence of a PFO: the combination of these mutations with PFO has been associated with a 4- to 5-fold increased risk of cerebral ischaemia, likely through facilitation of paradoxical embolism [7].

Inflammatory and infectious vasculopathies

Primary angiitis of the central nervous system (PACNS), although rare, illustrates the potential consequences of delayed diagnosis. Patients may initially present with headache, cognitive changes, or focal neurological deficits, and the clinical picture can mimic more common stroke mechanisms. Because PACNS requires prompt immunosuppressive treatment, failure to recognise the disease early may significantly worsen long-term outcomes [8].

Importantly, PACNS is not the only inflammatory condition that may affect the cerebral vasculature. Central nervous system involvement can also occur in systemic vasculitides such as giant cell arteritis, Takayasu arteritis, polyarteritis nodosa, or ANCA-associated vasculitides. In addition, infectious vasculopathies, e.g., caused by varicella–zoster virus, HIV, or syphilis, must be carefully excluded before immunosuppressive therapy is initiated [9].

Rare but important differential diagnoses
Additional rare conditions can also present with stroke in young adults. These include reversible cerebral vasoconstriction syndrome (RCVS), which typically manifests with thunderclap headaches and transient multifocal vasoconstriction of the cerebral arteries [10]. Other important differential diagnoses include Moyamoya angiopathy, characterised by progressive stenosis of the intracranial carotid circulation with the development of fragile collateral vessels [11].

Genetic and metabolic disorders must also be considered: monogenic disorders account for up to 7% of strokes in young adults [12]. Prominent examples include CADASIL, the most common monogenic cause of cerebral small vessel disease, typically presenting with migraine with aura, recurrent subcortical strokes, and progressive cognitive decline [13]. Fabry disease is particularly important to diagnose given the availability of enzyme replacement therapy. Mitochondrial disorders such as MELAS should also be considered, as stroke-like episodes may clinically mimic ischaemic stroke despite a distinct, non-vascular pathophysiology [14]. Although individually rare, these conditions become particularly relevant when stroke occurs in young individuals without conventional vascular risk factors.

Conclusion
These observations underline a key principle in the management of juvenile stroke: while acute treatment pathways may be similar across age groups, the search for an underlying cause must be tailored to the patient’s age and clinical context. Identifying the specific mechanism is crucial not only to understand why the event occurred, but also to guide targeted strategies for secondary prevention.

References

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