Transient neurological events in childhood moyamoya disease

Patients sometimes experience transient neurological events (TNEs) during the early postoperative period after revascularization surgery for childhood moyamoya disease. The clinical background and pathophysiology of TNEs remain unclear. This study aimed to evaluate the incidence rate of TNEs and discuss the factors associated with pediatric moyamoya disease.

The authors retrospectively reviewed 110 cerebral hemispheres of 61 pediatric patients younger than 15 years who were treated from 2011 to 2020. All children underwent either simple double-direct or combined revascularization surgery. Of these 61 patients, 52 underwent bilateral surgery and 9 underwent unilateral surgery. The authors calculated the incidence of TNEs in accordance with a previously reported TNE definition. Cerebral blood flow (CBF) was evaluated in all eligible cases with xenon CT immediately after revascularization surgery.

The incidence rate of TNEs in patients with childhood moyamoya disease was 26.4%. TNEs occurred after an average (range) of 6.26 (2-12) days postoperatively without triggers, and all identified TNEs spontaneously resolved within 2 weeks. The most common symptoms were dysarthria, facial palsy, and numbness around the mouth, followed by sensory disturbance of the upper extremities. The presence of focal hyperperfusion on xenon CT performed immediately after revascularization surgery was strongly correlated with the incidence of TNEs (p = 0.0001). Focal hyperperfusion was observed in 43 of 110 operative sides (39.1%). Notably, only 25.6% of patients with focal hyperperfusion showed numerical global hyperperfusion. In addition, a decrease in CBF compared with the thalamic region in the contralateral side was observed in TNE-affected cases (p = 0.0443).

TNEs occurred more frequently in childhood moyamoya disease patients than expected. The clinical background, including symptoms, timing, and duration, was almost identical to TNEs in adults. Focal hyperperfusion, rather than numerical global hyperperfusion, was strongly correlated with the incidence of TNEs. Furthermore, the authors advocate the notion that a clinical course where symptoms occur without triggers may be a unique characteristic of TNEs, especially in childhood moyamoya disease.