Thesis defense Frank van Rooij (Donders series 314)

14 June 2018

Promotors: prof. dr. F.de Leeuw, prof. dr. C. Klijn
Copromotor: dr. E. van Dijk

Transient neurological attacks. Neuroimaging, etiology, and cognitive consequences

The diagnosis of transient ischemic attack (TIA) is often difficult to establish. Early diffusion-weighted imaging (DWI) may show signs of recent ischemia. In the absence of focal neurological symptoms, an attack of short-lasting neurological symptoms is often referred to as a transient neurological attack (TNA). Although both TIA and TNA harbor the term transient in their names, many patients report cognitive and other complaints well beyond the point of initial symptom resolution.

This thesis was dedicated to TIA and TNA and aimed to unravel the etiology and prognosis of this spectrum of transient episodes of neurological dysfunction. In the first part we showed that clinically diagnosing TIA fails to adequately identify those patients with proven cerebral ischemia. In the second part we focused on possible lasting cognitive effects of TIA or TNA and found that cognitive impairment was present in more than a third of patients and mostly affected the cognitive domain of executive function. An initial DWI lesion, but not other markers for cerebrovascular macrostructural damage, was associated with worse cognitive function in the first 6 months after TIA or TNA. Also, fatigue and subjective cognitive impairment increased in severity after TIA or TNA, but only in those individuals with an initial DWI lesion. As a first step in establishing a ground for the hypothesis that microstructural damage after TIA or TNA may cause lasting cognitive symptoms afterwards, we used diffusion tensor imaging (DTI) in the third part of this thesis. We identified marginal but significant differences suggesting a worse cerebral microstructure in DWI-positive patients >6 months after the initial event.

The studies in this thesis show that the diagnosis of TIA remains difficult, and distinguishing vascular form nonvascular events seems most important. Neuroimaging, especially DWI, can help in determining which patients deserve vascular work-up and secondary prevention. Finally, although the word transient is incorporated in both TIA and TNA, many patients experience symptoms that are far from transient and deserve further attention.