Analysis of cerebrospinal pulse wave amplitude and correlation with optic disc morphology in Idiopathic Intracranial Hypertension

Aims: Aims of this thesis are to evaluate the features of cerebrospinal fluid (CSF) pulse wave amplitude (pwa) of IIH by lumbar measurements of CSF pressure during intracranial pressure (ICP) monitoring, and to correlate the CSF pwa magnitude to the level of optic disc damage in patients suffering from IIH. Methods: The thesis consists of two parts. Part I assesses the CSF pwa value in IIH by short-term (1-hour) monitoring by lumbar puncture and compared with an age-matched control group. CSF pwa values were collected with the same method of analisys in age-matched controls and IIH patients. Part II assesses optic disc morphology in the same patients by using Optic Coerence Tomography and than describes Optic disc parameters associated with raised CSF pressure and raised CSF pwa values in IIH with and without papilledema groups. Results: We found that the 75% of IIH patients have raised CSF mean pwa as compared to control group. Of the 75% of IIH patients that presented raised CSF pwa during short-term monitoring, the 57.3% was suffering from IIHWP and the 42.7% was IIHWOP. OCT measurements collected in IIHWP patients, suffering from both raised CSF mean pressure and raised CSF mean pwa values, showed all abnormal neuroretinal parameters: rim area and thickness, cup volume and cup-to-disc ratio (C/D), retinal nerve fiber layer (RNFL). OCT measurements collected in IIHWOP patients suffering from raised CSF mean pressure, showed abnormal both rim area and thickness, cup volume and C/D, but rather normal RNFL. Furthermore, we found statistical significance when we correlated CSF mean pressure with RNFL (r=0.60, p=0.042) and CSF pwa with RNFL (r=0.77, p=0.028; Fig.3b) collected form all participants. No correlation was found for CSF opening pressure and RNFL (r=0.34; p=0.06) among patients. Conclusions: Our data show that, during CSF short-term monitoring by lumbar access, both CSF mean pressure and CSF mean pwa are increased in IIH group if compared to control group as expression of reduced intracranial compliance. Neuroretinal structures are more damaged in IIH patients suffering from both raised CSF mean pressure and CSF mean pwa. The lumbar CSFP pwa could be used to evaluate the intracranial compliance and the evolution of optic nerve head damage in IIH patients.