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Colman BD, Boonstra F, Nguyen MN, Raviskanthan S, Sumithran P, White O, Hutton EJ, Fielding J, van der Walt A. Understanding the pathophysiology of idiopathic intracranial hypertension (IIH): a review of recent developments. J Neurol Neurosurg Psychiatry 2024; 95:375-383. [PMID: 37798095 DOI: 10.1136/jnnp-2023-332222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 09/15/2023] [Indexed: 10/07/2023]
Abstract
Idiopathic intracranial hypertension (IIH) is a condition of significant morbidity and rising prevalence. It typically affects young people living with obesity, mostly women of reproductive age, and can present with headaches, visual abnormalities, tinnitus and cognitive dysfunction. Raised intracranial pressure without a secondary identified cause remains a key diagnostic feature of this condition, however, the underlying pathophysiological mechanisms that drive this increase are poorly understood. Previous theories have focused on cerebrospinal fluid (CSF) hypersecretion or impaired reabsorption, however, the recent characterisation of the glymphatic system in many other neurological conditions necessitates a re-evaluation of these hypotheses. Further, the impact of metabolic dysfunction and hormonal dysregulation in this population group must also be considered. Given the emerging evidence, it is likely that IIH is triggered by the interaction of multiple aetiological factors that ultimately results in the disruption of CSF dynamics. This review aims to provide a comprehensive update on the current theories regarding the pathogenesis of IIH.
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Affiliation(s)
- Blake D Colman
- Department of Neuroscience, Monash University Faculty of Medicine Nursing and Health Sciences, Clayton, Victoria, Australia
- Department of Neurology, Alfred Hospital, Melbourne, Victoria, Australia
| | - Frederique Boonstra
- Department of Neuroscience, Monash University Faculty of Medicine Nursing and Health Sciences, Clayton, Victoria, Australia
| | - Minh Nl Nguyen
- Department of Neuroscience, Monash University Faculty of Medicine Nursing and Health Sciences, Clayton, Victoria, Australia
- Department of Neurology, Alfred Hospital, Melbourne, Victoria, Australia
| | | | - Priya Sumithran
- Department of Surgery, Monash University Faculty of Medicine Nursing and Health Sciences, Clayton, Victoria, Australia
- Department of Endocrinology, Alfred Hospital, Melbourne, Victoria, Australia
| | - Owen White
- Department of Neurology, Alfred Hospital, Melbourne, Victoria, Australia
- Department of Neuroscience, Monash University Central Clinical School, Clayton, Victoria, Australia
| | - Elspeth J Hutton
- Department of Neuroscience, Monash University Faculty of Medicine Nursing and Health Sciences, Clayton, Victoria, Australia
- Department of Neurology, Alfred Hospital, Melbourne, Victoria, Australia
| | - Joanne Fielding
- Department of Neuroscience, Monash University Faculty of Medicine Nursing and Health Sciences, Clayton, Victoria, Australia
| | - Anneke van der Walt
- Department of Neuroscience, Monash University Faculty of Medicine Nursing and Health Sciences, Clayton, Victoria, Australia
- Department of Neurology, Alfred Hospital, Melbourne, Victoria, Australia
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Wardman JH, Andreassen SN, Toft-Bertelsen TL, Jensen MN, Wilhjelm JE, Styrishave B, Hamann S, Heegaard S, Sinclair AJ, MacAulay N. CSF hyperdynamics in rats mimicking the obesity and androgen excess characteristic of patients with idiopathic intracranial hypertension. Fluids Barriers CNS 2024; 21:10. [PMID: 38273331 PMCID: PMC10810013 DOI: 10.1186/s12987-024-00511-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/05/2024] [Indexed: 01/27/2024] Open
Abstract
BACKGROUND Idiopathic intracranial hypertension (IIH) is a syndrome exhibiting elevated intracranial pressure (ICP), visual disturbances, and severe headache. IIH primarily affects young obese women, though it can occur in individuals of any age, BMI, and sex. IIH is characterized by systemic metabolic dysregulation with a profile of increased androgen hormones. However, the contribution of obesity/hormonal perturbations to cerebrospinal fluid (CSF) dynamics remains unresolved. METHODS We employed obese female Zucker rats and adjuvant testosterone to reveal IIH causal drivers. ICP and CSF dynamics were determined with in vivo experimentation and magnetic resonance imaging, testosterone levels assessed with mass spectrometry, and choroid plexus function revealed with transcriptomics. RESULTS Obese rats had undisturbed CSF testosterone levels and no changes in ICP or CSF dynamics. Adjuvant testosterone treatment of obese rats elevated the CSF secretion rate, although with no effect on the ICP, due to elevated CSF drainage capacity of these rats. CONCLUSIONS Obesity in itself therefore does not suffice to recapitulate the IIH symptoms in rats, but modulation of CSF dynamics appears with adjuvant testosterone treatment, which mimics the androgen excess observed in female IIH patients. Obesity-induced androgen dysregulation may thus contribute to the disease mechanism of IIH and could potentially serve as a future therapeutic target.
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Affiliation(s)
- Jonathan H Wardman
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, Copenhagen, DK-2200, Denmark
| | - Søren Norge Andreassen
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, Copenhagen, DK-2200, Denmark
| | - Trine L Toft-Bertelsen
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, Copenhagen, DK-2200, Denmark
| | - Mette Nyholm Jensen
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, Copenhagen, DK-2200, Denmark
| | - Jens E Wilhjelm
- Department of Neurophysiology, Rigshospitalet, Copenhagen, Denmark
- Department of Health Technology, Technical University of Denmark, Copenhagen, Denmark
| | - Bjarne Styrishave
- Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark
| | - Steffen Hamann
- Department of Ophthalmology, Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Steffen Heegaard
- Department of Ophthalmology, Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Alexandra J Sinclair
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Nanna MacAulay
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, Copenhagen, DK-2200, Denmark.
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Wardman JH, Jensen MN, Andreassen SN, Styrishave B, Wilhjelm JE, Sinclair AJ, MacAulay N. Modelling idiopathic intracranial hypertension in rats: contributions of high fat diet and testosterone to intracranial pressure and cerebrospinal fluid production. Fluids Barriers CNS 2023; 20:44. [PMID: 37328884 DOI: 10.1186/s12987-023-00436-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 04/29/2023] [Indexed: 06/18/2023] Open
Abstract
BACKGROUND Idiopathic intracranial hypertension (IIH) is a condition characterized by increased intracranial pressure (ICP), impaired vision, and headache. Most cases of IIH occur in obese women of childbearing age, though age, BMI, and female sex do not encompass all aspects of IIH pathophysiology. Systemic metabolic dysregulation has been identified in IIH with a profile of androgen excess. However, the mechanistic coupling between obesity/hormonal perturbations and cerebrospinal fluid dynamics remains unresolved. METHODS Female Wistar rats were either fed a high fat diet (HFD) for 21 weeks or exposed to adjuvant testosterone treatment for 28 days to recapitulate IIH causal drivers. Cerebrospinal fluid (CSF) and blood testosterone levels were determined with mass spectrometry, ICP and CSF dynamics with in vivo experimentation, and the choroid plexus function revealed with transcriptomics and ex vivo isotope-based flux assays. RESULTS HFD-fed rats presented with increased ICP (65%), which was accompanied by increased CSF outflow resistance (50%) without altered CSF secretion rate or choroid plexus gene expression. Chronic adjuvant testosterone treatment of lean rats caused elevated ICP (55%) and CSF secretion rate (85%), in association with increased activity of the choroid plexus Na+,K+,2Cl- cotransporter, NKCC1. CONCLUSIONS HFD-induced ICP elevation in experimental rats occurred with decreased CSF drainage capacity. Adjuvant testosterone, mimicking the androgen excess observed in female IIH patients, elevated the CSF secretion rate and thus ICP. Obesity-induced androgen dysregulation may thus contribute to the disease mechanism of IIH.
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Affiliation(s)
- Jonathan H Wardman
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark
| | - Mette N Jensen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark
| | - Søren N Andreassen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark
| | - Bjarne Styrishave
- Department of Pharmacy, University of Copenhagen, Copenhagen, Denmark
| | - Jens E Wilhjelm
- Department of Health Technology, The Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Alexandra J Sinclair
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | - Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen N, Denmark.
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Jin P, Munson JM. Fluids and flows in brain cancer and neurological disorders. WIREs Mech Dis 2023; 15:e1582. [PMID: 36000149 PMCID: PMC9869390 DOI: 10.1002/wsbm.1582] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 06/21/2022] [Accepted: 06/27/2022] [Indexed: 01/31/2023]
Abstract
Interstitial fluid (IF) and cerebrospinal fluid (CSF) are an integral part of the brain, serving to cushion and protect the brain parenchymal cells against damage and aid in their function. The brain IF contains various ions, nutrients, waste products, peptides, hormones, and neurotransmitters. IF moves primarily by pressure-dependent bulk flow through brain parenchyma, draining into the ventricular CSF. The brain ventricles and subarachnoid spaces are filled with CSF which circulates through the perivascular spaces. It also flows into the IF space regulated, in part, by aquaporin channels, removing waste solutes through a process of IF-CSF mixing. During disease development, the composition, flow, and volume of these fluids changes and can lead to brain cell dysfunction. With the improvement of imaging technology and the help of genomic profiling, more information has been and can be obtained from brain fluids; however, the role of CSF and IF in brain cancer and neurobiological disease is still limited. Here we outline recent advances of our knowledge of brain fluid flow in cancer and neurodegenerative disease based on our understanding of its dynamics and composition. This article is categorized under: Cancer > Biomedical Engineering Neurological Diseases > Biomedical Engineering.
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Affiliation(s)
- Peng Jin
- Fralin Biomedical Research Institute, Department of Biomedical Engineering and Mechanics Virginia Polytechnic Institute and State University Roanoke Virginia USA
| | - Jennifer M. Munson
- Fralin Biomedical Research Institute, Department of Biomedical Engineering and Mechanics Virginia Polytechnic Institute and State University Roanoke Virginia USA
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