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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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Petzold A, Coric D, Balk LJ, Hamann S, Uitdehaag BMJ, Denniston AK, Keane PA, Crabb DP. Longitudinal Development of Peripapillary Hyper-Reflective Ovoid Masslike Structures Suggests a Novel Pathological Pathway in Multiple Sclerosis. Ann Neurol 2020; 88:309-319. [PMID: 32426856 PMCID: PMC7496959 DOI: 10.1002/ana.25782] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 05/13/2020] [Accepted: 05/14/2020] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Peripapillary hyper-reflective ovoid masslike structures (PHOMS) are a new spectral domain optical coherence tomography (OCT) finding. METHODS This prospective, longitudinal study included patients (n = 212) with multiple sclerosis (MS; n = 418 eyes), 59 healthy controls (HCs; n = 117 eyes), and 267 non-MS disease controls (534 eyes). OCT and diffusion tensor imaging were used. RESULTS There were no PHOMS in HC eyes (0/117, 0%). The prevalence of PHOMS was significantly higher in patients with MS (34/212, p = 0.001) and MS eyes (45/418, p = 0.0002) when compared to HCs (0/59, 0/117). The inter-rater agreement for PHOMS was 97.9% (kappa = 0.951). PHOMS were present in 16% of patients with relapsing-remitting, 16% of patients with progressive, and 12% of patients with secondary progressive disease course (2% of eyes). There was no relationship of PHOMS with age, disease duration, disease course, disability, or disease-modifying treatments. The fractional anisotropy of the optic radiations was lower in patients without PHOMS (0.814) when compared to patients with PHOMS (0.845, p = 0.03). The majority of PHOMS remained stable, but increase in size and de novo development of PHOMS were also observed. In non-MS disease controls, PHOMS were observed in intracranial hypertension (62%), optic disc drusen (47%), anomalous optic discs (44%), isolated optic neuritis (19%), and optic atrophy (12%). INTERPRETATION These data suggest that PHOMS are a novel finding in MS pathology. Future research is needed to determine whether development of PHOMS in MS is due to intermittently raised intracranial pressure or an otherwise impaired "glymphatic" outflow from eye to brain. ANN NEUROL 2020;88:309-319.
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Affiliation(s)
- Axel Petzold
- Dutch Expertise Center for Neuro‐Ophthalmology and Multiple Sclerosis Center, Departments of Neurology and OphthalmologyAmsterdam University Medical CenterAmsterdamThe Netherlands
- Moorfields Eye Hospital and National Hospital for Neurology and NeurosurgeryLondonUnited Kingdom
- University College London Queen Square Institute of NeurologyLondonUnited Kingdom
- National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital and University College London Institute of OphthalmologyLondonUnited Kingdom
| | - Danko Coric
- Dutch Expertise Center for Neuro‐Ophthalmology and Multiple Sclerosis Center, Departments of Neurology and OphthalmologyAmsterdam University Medical CenterAmsterdamThe Netherlands
- Multiple Sclerosis Center and Department of NeurologyAmsterdam University Medical CenterAmsterdamThe Netherlands
| | - Lisanne J. Balk
- Dutch Expertise Center for Neuro‐Ophthalmology and Multiple Sclerosis Center, Departments of Neurology and OphthalmologyAmsterdam University Medical CenterAmsterdamThe Netherlands
- Multiple Sclerosis Center and Department of NeurologyAmsterdam University Medical CenterAmsterdamThe Netherlands
| | - Steffen Hamann
- Department of Ophthalmology, RigshospitaletUniversity of CopenhagenCopenhagenDenmark
| | - Bernard M. J. Uitdehaag
- Multiple Sclerosis Center and Department of NeurologyAmsterdam University Medical CenterAmsterdamThe Netherlands
| | - Alastair K. Denniston
- National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital and University College London Institute of OphthalmologyLondonUnited Kingdom
- Department of OphthalmologyUniversity Hospitals Birmingham National Health Service Foundation TrustBirminghamUnited Kingdom
- Academic Unit of OphthalmologyInstitute of Inflammation and Ageing, University of BirminghamBirminghamUnited Kingdom
| | - Pearse A. Keane
- Department of Ophthalmology, RigshospitaletUniversity of CopenhagenCopenhagenDenmark
| | - David P. Crabb
- Optometry and Visual SciencesCity, University of LondonLondonUnited Kingdom
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