Idiopathic Intracranial Hypertension and Multiple Sclerosis

Idiopathic Intracranial Hypertension Preceding Tumefactive Multiple Sclerosis

Idiopathic intracranial hypertension (IIH) and multiple sclerosis (MS) are rare neurological disorders that largely affect females within the reproductive age group. The clinical pictures of both diseases can overlap, which therefore places great importance on accurately studying and reporting their concurrence. Therein, we report a case of IIH presenting and progressing simultaneously with MS. This young, previously healthy female presented with the primary complaint of a severe right-sided headache associated with blurred vision and a finding of papilledema. The initial investigations including a lumbar puncture (LP) that revealed high opening pressure (more than 25 mm H2O) with normal cerebrospinal fluid (CSF) analysis led to an impression of idiopathic intracranial hypertension, and she was treated accordingly with acetazolamide and scheduled for regular follow-ups with both neurology and neuro-ophthalmology. However, about two months after the initial presentation, she complained of unusual headaches, and a neuro-ophthalmology clinical evaluation revealed complete right homonymous hemianopia, suggesting a lesion in the left temporo-parietal occipital region. The patient was thus admitted as a case of cerebral edema following an urgent brain magnetic resonance imaging (MRI). After obtaining thorough imaging and workup, the patient was given steroids and markedly improved, favoring a diagnosis of tumefactive MS with IIH.

Blockade of VEGFR3 signaling leads to functional impairment of dural lymphatic vessels without affecting autoimmune neuroinflammation

The recent discovery of lymphatic vessels (LVs) in the dura mater, the outermost layer of meninges around the central nervous system (CNS), has opened a possibility for the development of alternative therapeutics for CNS disorders. The vascular endothelial growth factor C (VEGF-C)/VEGF receptor 3 (VEGFR3) signaling pathway is essential for the development and maintenance of dural LVs. However, its significance in mediating dural lymphatic function in CNS autoimmunity is unclear. We show that inhibition of the VEGF-C/VEGFR3 signaling pathway using a monoclonal VEGFR3-blocking antibody, a soluble VEGF-C/D trap, or deletion of the Vegfr3 gene in adult lymphatic endothelium causes notable regression and functional impairment of dural LVs but has no effect on the development of CNS autoimmunity in mice. During autoimmune neuroinflammation, the dura mater was only minimally affected, and neuroinflammation-induced helper T (T_H) cell recruitment, activation, and polarization were significantly less pronounced in the dura mater than in the CNS. In support of this notion, during autoimmune neuroinflammation, blood vascular endothelial cells in the cranial and spinal dura expressed lower levels of cell adhesion molecules and chemokines, and antigen-presenting cells (i.e., macrophages and dendritic cells) had lower expression of chemokines, MHC class II-associated molecules, and costimulatory molecules than their counterparts in the brain and spinal cord, respectively. The significantly weaker T_H cell responses in the dura mater may explain why dural LVs do not contribute directly to CNS autoimmunity.