Introduction:
Obstructive sleep apnea (OSA) is a highly prevalent sleep-related breathing disorder characterized by repetitive upper airway obstruction during sleep, resulting in intermittent hypoxia, hypercapnia, and marked fluctuations in intrathoracic pressure. These physiological disturbances have systemic consequences and are increasingly recognized for their impact on cerebral hemodynamics and intracranial pressure (ICP). Understanding this relationship is particularly critical in patients with coexisting neurological disorders.

Objective:
This systematic review aims to synthesize current evidence on the bidirectional relationship between OSA and elevated ICP, with an emphasis on underlying mechanisms, clinical implications, and therapeutic considerations across conditions such as idiopathic intracranial hypertension (IIH), traumatic brain injury (TBI), and hydrocephalus.

Methods:
A comprehensive literature search was conducted in accordance with PRISMA guidelines across PubMed, Scopus, Web of Science, and Google Scholar. Search terms included combinations of Medical Subject Headings (MeSH) and Boolean operators, with no date restrictions. Thirty-five studies met the inclusion criteria, covering both clinical and experimental data.

Findings:
Evidence from the reviewed studies suggests that the cyclical hypoxia and intrathoracic pressure changes in OSA may lead to transient elevations in ICP and disrupt cerebrospinal fluid (CSF) dynamics. These effects may exacerbate symptoms or disease progression in patients with underlying intracranial pathology. While CPAP therapy remains the standard of care for OSA, its impact on ICP is variable, with some reports indicating a benefit and others suggesting a potential elevation of ICP, particularly in specific patient populations.

Conclusion:
There is growing support for a complex and potentially bidirectional interaction between OSA and ICP. However, inconsistencies across study methodologies and patient cohorts limit the ability to draw definitive conclusions. Future research should focus on standardized assessment protocols and targeted investigations to better understand how OSA management may influence ICP regulation and neurological outcomes.