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RESEARCH PRODUCT

Abnormal BAEP and internal auditory canal MRI in intracranial hypotension

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Intracranial hypotension (IH) is a treatable condition due to cerebrospinal fluid leak, characterised by variable clinical and MRI findings.1 Positional headache, neck stiffness, hearing changes with subdural fluid collection, enhancement of meninges, engorgement of venous structures and brain sagging are among the most frequent clinical and MRI findings. Typical abnormalities are found in 68%–85% of patients1. Hearing alterations (ranging from misperception to severe hearing loss) are known clinical symptoms of IH.1 The mechanism involves secondary perilymph depression due to patency of the cochlear aqueduct, inducing a compensatory expansion of the endolymphatic compartment, decreasing basilar or Reissner’s membrane compliance. Some reports showed internal auditory canal (IAC) MRI abnormalities in IH.1 As brainstem acoustic evoked potentials (BAEPs) track internal ear structure and brainstem acoustic pathways integrity,2 we assessed possible BAEP abnormalities in IH. In order to improve IAC imaging we performed contrast-enhanced spectral adiabatic inversion recovery (SPAIR) 3T MRI in each patient with IH. The study was carried out according to the Declaration of Helsinki and approved by the local ethical committee of Chieti-Pescara, Italy. Eighteen patients (12 women, 43±3 years old) presented with IH with one or a combination of the following symptoms: orthostatic headache (100%), chronic headache (89%), hearing loss, tinnitus or acoustic misperception (78%), confusion (22%) and lethargy (22%). IH was diagnosed 45–750 days after onset of symptoms, and recovered in 18–48 days, with bed rest and hydration (56%) and blood patch (33%). BAEPs were recorded according to standard guidelines, with 90 dB sensation level (SL) 10 Hz …