Pediatric craniocerebral growth mismatch and the elastic dynamic model of the Monro-Kellie doctrine: A pediatric neurosurgical perspective.

The classical Monro-Kellie doctrine conceptualizes the cranium as a rigid container with fixed volume, a principle that has guided intracranial pressure (ICP) management for over two centuries. However, this model inadequately addresses the unique physiology of the developing pediatric skull, which exhibits significant age-dependent compliance due to open sutures and fontanelles. This review proposes an elastic dynamic model of the pediatric cranium and introduces the concept of Pediatric Craniocerebral Growth Mismatch (PCGM) as a unifying clinical framework. PCGM is defined as the mismatch between the brain's growth trajectory and the cranial vault's adaptive capacity under pathological conditions. By incorporating the term ΔV_skull_compliance(age) into the traditional Monro-Kellie equation, the pediatric cranium is reconceptualized as an elastic and dynamic system. PCGM manifests across a spectrum of conditions, including craniosynostosis (restriction type) and chronic hydrocephalus or giant intracranial tumors (expansion type). In giant tumors, PCGM typically follows a biphasic pattern: chronic compensatory cranial expansion followed by acute post-resection volume mismatch. This framework is illustrated through the staged reconstruction of a growing skull fracture with encephalomeningocele in an infant. We propose three core management principles for PCGM: (1) individualized ICP management using age- and compliance-adapted strategies, (2) timely intervention within the compensatory window of cranial plasticity, and (3) long-term neurodevelopmental surveillance. For giant intracranial tumors, a hydrocephalus-first approach combined with staged resection is advocated to mitigate acute volume mismatch. Ultimately, pediatric neurosurgery must evolve beyond mere ICP reduction toward the optimization of long-term craniocerebral growth equilibrium. This elastic dynamic model provides a pediatric-specific advancement of the Monro-Kellie doctrine with important implications for surgical timing and strategy.