Endolymphatic hydrops in idiopathic intracranial hypertension: prevalence and clinical outcome after lumbar puncture. Preliminary data

Idiopathic intracranial hypertension is characterized by raised intracranial pressure (ICP) without any underlying pathology, presenting with (IIH) or without papilledema (IIHWOP). Headache, often on daily basis, is the most frequent symptom. Among audiovestibular symptoms, tinnitus and dizziness are commonly reported, while vertigo and hearing impairment are infrequent reports. Endolymphatic hydrops (ELH) is the typical histopathologic feature of Ménière disease, a condition featured by episodes of vertigo, dizziness, fluctuating hearing loss, tinnitus, and aural fullness. Evidences suggest that ICP is transmitted to inner ear. The aim of this study is to investigate the prevalence of ELH symptoms in IIH/IIHWOP and the relationship between the raised ICP and ELH. The prevalence of chronic headache and of ELH symptoms was investigated in a consecutive series of IIH/IIHWOP patients, and a standard audiometry with hearing threshold measurement (pure-tone average-PTA) was performed. Differences in chronic headache and ELH symptoms prevalence and changes of PTA threshold were calculated after ICP normalization by lumbar puncture (LP). Thirty-one patients (17 with IIH and 14 with IIHWOP) were included. Before LP, chronic headache was present in 93.5%. The percentages of patients reporting tinnitus, dizziness, vertigo, and aural fullness were 67.7, 77.4, 22.6, and 61.3%, respectively. Headache frequency as well as ELH symptoms and PTA significantly improved after LP. The improvement of PTA and of ELH symptoms observed after LP in this series of IIH/IIHWOP patients indicates that a raised ICP, a condition known to be involved in the progression and refractoriness of migraine pain, has also a role in ELH. We propose that intracranial hypertension may represent the shared pathogenetic step explaining the large epidemiological comorbidity between migraine and vestibular symptoms, at present conceptualized as "vestibular migraine."