Cognitive Deficits and Neuropsychological Assessment in Non-Revascularized Moyamoya Disease Patients: a Systematic Review.

Moyamoya Angiopathy (MMA) is a rare, progressive, steno-occlusive cerebrovascular disorder. The disease can be idiopathic (Moyamoya Disease, MMD) or associated with heritable or acquired conditions (i.e., Moyamoya Syndrome, MMS). Among clinical symptoms of MMA, cognitive aspects are acknowledged but not well-characterized, and their proper neuropsychological assessment has never been standardized. We conducted a systematic review to investigate the characteristics of cognitive deficits in non-revascularized adults MMD patients, as well as the main neuropsychological tests used for their evaluation. The literature search was performed by two independent reviewers across three different databases, including PubMed, EMBASE, and Scopus. Quality assessment was independently performed by two reviewers through the Johanna Briggs Institute critical appraisal tools. Data on sample size, patients' demographics, age at diagnosis, clinical and radiological characteristics of MMD, administered neuropsychological tests, prevalence of cognitive impairment (CI), and altered cognitive domains were extracted. The literature search allowed the inclusion of 12 papers, confirming the limited literature on this topic. The prevalence of CI ranged from 23 to 92% across studies. Executive functions, especially processing speed and cognitive flexibility, followed by memory skills appeared to be the most affected cognitive domains. Conversely, other cognitive functions have been less investigated. The most commonly used neuropsychological tests were the Trail Making Test, the Digit Span test, and Verbal Fluency. Despite growing awareness and knowledge of cognitive aspects in patients with MMD, inconsistency remains in identifying specific neuropsychological profiles, and no standardized assessment protocol has yet been established.