Case series evidence for improvement of executive functions after late cranioplasty.

Objective: Craniectomy, used to relieve refractory intracranial pressure in traumatic brain injury (TBI), may cause cognitive deficits which could be improved by skull breach repair. This paper studied whether late cranioplasty improves a specific pattern of cognitive functions. Design: A case series of five TBI patients with craniectomy undergoing late cranioplasty (median interval time: 14 months, range: 12-36). Methods: Longitudinal neuropsychological and brain MRI assessments 1 week before cranioplasty and 3 months later. Results: After cranioplasty, mean score of the verbal fluency test improved compared to pre-cranioplasty (p = 0.02). Similarly, significant improvements after cranioplasty were observed in other tests scores exploring executive functions, such as working memory (p = 0.03) and speed of attention (p = 0.04), independently from the size and site of cranioplasty. Conclusions: The cognitive improvement induced by cranioplasty, even when performed after a long interval from craniectomy, may be due to the restoration of physiological cerebrospinal fluid circulation which, in turn, allows an efficient brain volume transmission signal circulation. The restoration of this essential way of signal communication seems to affect large-scale neuronal networks responsible for the executive functions.