scholarly journals Spaceflight-Induced Intracranial Hypertension and Visual Impairment: Pathophysiology and Countermeasures

2018 ◽  
Vol 98 (1) ◽  
pp. 59-87 ◽  
Author(s):  
Li-Fan Zhang ◽  
Alan R. Hargens
Keyword(s):  
Optic Nerve ◽  
Intracranial Pressure ◽  
Visual Impairment ◽  
Elevated Pressure ◽  
Lamina Cribrosa ◽  
Fluid System ◽  
Fluid Systems ◽  
Long Duration ◽  
Multiple Structures ◽  
Intracranial Circulation

Visual impairment intracranial pressure (VIIP) syndrome is considered an unexplained major risk for future long-duration spaceflight. NASA recently redefined this syndrome as Spaceflight-Associated Neuro-ocular Syndrome (SANS). Evidence thus reviewed supports that chronic, mildly elevated intracranial pressure (ICP) in space (as opposed to more variable ICP with posture and activity on Earth) is largely accounted for by loss of hydrostatic pressures and altered hemodynamics in the intracranial circulation and the cerebrospinal fluid system. In space, an elevated pressure gradient across the lamina cribrosa, caused by a chronic but mildly elevated ICP, likely elicits adaptations of multiple structures and fluid systems in the eye which manifest themselves as the VIIP syndrome. A chronic mismatch between ICP and intraocular pressure (IOP) in space may acclimate the optic nerve head, lamina cribrosa, and optic nerve subarachnoid space to a condition that is maladaptive to Earth, all contributing to the pathogenesis of space VIIP syndrome. Relevant findings help to evaluate whether artificial gravity is an appropriate countermeasure to prevent this seemingly adverse effect of long-duration spaceflight.

Intracranial Pressure Influences the Behavior of the Optic Nerve Head

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Yi Hua ◽  
Junfei Tong ◽  
Deepta Ghate ◽  
Sachin Kedar ◽  
Linxia Gu
Keyword(s):  
Optic Nerve ◽  
Intracranial Pressure ◽  
Optic Nerve Head ◽  
Neural Tissue ◽  
Lamina Cribrosa ◽  
Patient Specific ◽  
Orthogonal Experimental Design ◽  
Ischemic Optic Neuropathy ◽  
Pia Mater ◽  
Minimal Impact

In this work, the biomechanical responses of the optic nerve head (ONH) to acute elevations in intracranial pressure (ICP) were systematically investigated through numerical modeling. An orthogonal experimental design was developed to quantify the influence of ten input factors that govern the anatomy and material properties of the ONH on the peak maximum principal strain (MPS) in the lamina cribrosa (LC) and postlaminar neural tissue (PLNT). Results showed that the sensitivity of ONH responses to various input factors was region-specific. In the LC, the peak MPS was most strongly dependent on the sclera thickness, LC modulus, and scleral canal size, whereas in the PLNT, the peak MPS was more sensitive to the scleral canal size, neural tissue modulus, and pia mater modulus. The enforcement of clinically relevant ICP in the retro-orbital subarachnoid space influenced the sensitivity analysis. It also induced much larger strains in the PLNT than in the LC. Moreover, acute elevation of ICP leads to dramatic strain distribution changes in the PLNT, but had minimal impact on the LC. This work could help to better understand patient-specific responses, to provide guidance on biomechanical factors resulting in optic nerve diseases, such as glaucoma, papilledema, and ischemic optic neuropathy, and to illuminate the possibilities for exploiting their potential to treat and prevent ONH diseases.

The Coexistence of Olfactory Groove with Optic Nerve Sheath Meningioma Presenting with Anosmia: Case Report

2020 ◽  
Vol 16 ◽  
Author(s):  
Hatice Ferhan Kömürcü ◽  
Gıyas Ayberk ◽  
Ömer Anlar
Keyword(s):  
Case Report ◽  
Optic Nerve ◽  
Visual Impairment ◽  
Optic Nerve Sheath ◽  
Olfactory Groove ◽  
Nerve Sheath ◽  
Optic Nerve Sheath Meningioma ◽  
History Of ◽  
Olfactory Groove Meningioma ◽  
Memory Disturbance

Introduction: Meningiomas are the third most common intracranial tumors in adults after glial tumors and metastases. Olfactory groove meningiomas often grow without symptoms due to their slow growth rates and location in the frontal lobe. Optic nerve sheath meningiomas are benign neoplasms of the meninges surrounding the optic nerve. The coexistence of olfactory groove and optic nerve sheath meningiomas without any history of neurofibromatosis or radiotherapy has never been reported in the literature. Case Report: A 36-year-old female patient presenting with anosmia, headache, memory disturbance, and visual impairment and operated with the diagnosis of olfactory groove meningioma was reported. In the postoperative period, optic nerve sheath meningioma was detected in the imaging performed due to the persistence of visual impairment. Conclusion: Olfactory groove and optic nerve sheath meningiomas are rare tumors and can be diagnosed late because they progress slowly. Early diagnosis and treatment may affect the prognosis and morbidity of these patients favorably.

scholarly journals Migraine or idiopathic intracranial hypertension: Magnetic resonance venography and magnetic resonance imaging findings

2020 ◽  
Vol 33 (3) ◽  
pp. 244-251
Author(s):  
Aynur Guliyeva ◽  
Melda Apaydin ◽  
Yesim Beckmann ◽  
Gulten Sezgin ◽  
Fazil Gelal
Keyword(s):  
Magnetic Resonance Imaging ◽  
Optic Nerve ◽  
Magnetic Resonance ◽  
Intracranial Pressure ◽  
Pituitary Gland ◽  
Optic Nerve Sheath ◽  
Imaging Findings ◽  
Resonance Imaging ◽  
Chi Square ◽  
Nerve Sheath

Background Idiopathic intracranial hypertension (IIH) is a disease characterised by increased cerebral pressure without a mass or hydrocephalus. We aimed to differentiate migraine and IIH patients based on imaging findings. Results Patients with IIH ( n = 32), migraine patients ( n = 34) and control subjects ( n = 33) were evaluated. Routine magnetic resonance imaging, contrast-enhanced 3D magnetic resonance venography and/or T1-weighted 3D gradient-recalled echo were taken with a 1.5 T magnetic resonance scanner. Optic-nerve sheath distention, flattened posterior globe and the height of the pituitary gland were evaluated in the three groups. Transverse sinuses (TS) were evaluated with respect to score of attenuation/stenosis and distribution. Pearson chi-square, Fisher’s exact test and chi-square trend statistical analyses were used for comparisons between the groups. A p-value of <0.05 was considered statistically significant. Decreased pituitary gland height, optic-nerve sheath distention and flattened posterior globe were found to be statistically significant ( p < 0.001) in IIH patients. Bilateral TS stenosis was also more common in IIH patients than in the control group and migraine group ( p = 0.02). Conclusion Decreased pituitary gland height, optic-nerve sheath distention, flattened posterior globe, bilateral stenosis and discontinuity in TS are significant findings in differentiating IIH cases from healthy individuals and migraine patients. Bilateral TS stenosis may be the cause rather than the result of increased intracranial pressure. The increase in intracranial pressure, which is considered to be responsible for the pathophysiology of IIH, is not involved in the pathophysiology of migraine.

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