1. Progressive Paranasal Sinus Enlargement and Enophthalmos in a Case of Lowered Intracranial Pressure
J. Villanueva-Meyer, C. Glastonbury
UCSF Department of Radiology and Biomedical Imaging

2. Disclosures
The authors have nothing to disclose

3. Background
Immediate complications related to excessive cerebrospinal fluid shunting are well documented as the syndrome of intracranial hypotension. However, long-term complications related to chronically decreased intracranial pressure from excessive shunting are rarely encountered.

4. Purpose
We report a unique case of progressive enophthalmos and paranasl sinus enlargement as well as calvarial thickening in the setting of chronically lowered intracranial pressure.

5. Case Report: Presentation
A 44-year-old man presents in March 2015 with somnolence after complaining of severe headaches immediately prior to arrival
Emergent non-contrast CT examination of the head at presentation demonstrates tension pneumocephalus
Relevant history:
Central neurocytoma resection complicated by intraventricular hemorrhage requiring VP shunting in 2009

6. Case Report: Review of Imaging
Given the non-traumatic presentation and lack of recent surgical intervention, dehiscence of the markedly enlarged frontal sinuses was suggested as the etiology
High-resolution paranasal sinus CT further demonstrated marked thinning of the superior and posterior walls of the frontal sinuses bilaterally

7. Case Report: Review of Imaging
Compared to studies from six years prior, there had been progressive development of enophthalmos (green arrowhead), paranasal sinus enlargement (green asterisk), and calvarial thickening (white arrow) Of note, CT cisternography was not able to demonstrate a CSF leak *
2009
2015

8. Discussion: Common Complications
The syndrome of intracranial hypotension is a well-documented complication in the acute to subacute setting of CSF overshunting. Its imaging features include:
Supra- and infratentorial descent
Ventricular alteration and effacement of the basilar cisterns
Pituitary gland enlargement
Dural venous sinus distension
Subdural collections
Pachymeningeal enhancement
Chronic complications of longstanding CSF overshunting have rarely been reported

9. Discussion: Chronically Lowered Intracranial Pressure
Progressive paranasal sinus enlargement, enophthalmos, calvarial thickening, and spontaneous pneumocephalus are rare complications of chronic intracranial hypotension This constellation of findings is thought to represent the effect of negative intracranial pressure, in our case from the ventriculoperitoneal shunt, and a CSF leak Due to a presumed “ball-valve” mechanism, cisternography may fail to demonstrate the site of CSF leak
Familiarity with these imaging findings is important for the neuroradiologist to appropriately identify lowered intracranial pressure due to overshunting before a more serious complication such as pneumocephalus develops

10. References
Yoon MK, Parsa, AT, Horton JC. Skull thickening, paranasal sinus expansion, and sella turcica shrinkage from chronic intracranial hypotension: Case report. Journal of Neurosurgery: Pediatrics 2013; 11(6),
Aguilar EN, Ramirez MC, Zabala AB, et al. Delayed spontaneous pneumocephalus in ventriculoperitoneal shunting: Two case reports and literature review. Neurocirugia 2014; 25(2),
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