Functional magnetic resonance imaging of enhanced central auditory gain and electrophysiological correlates in a behavioral model of hyperacusis.

Hyperacusis is a debilitating hearing condition in which normal everyday sounds are perceived as exceedingly loud, annoying, aversive or even painful. The prevalence of hyperacusis approaches 10%, making it an important, but understudied medical condition. To noninvasively identify the neural correlates of hyperacusis in an animal model, we used sound-evoked functional magnetic resonance imaging (fMRI) to locate regions of abnormal activity in the central nervous system of rats with behavioral evidence of hyperacusis induced with an ototoxic drug (sodium salicylate, 250 mg/kg, i.p.). Reaction time-intensity measures of loudness-growth revealed behavioral evidence of salicylate-induced hyperacusis at high intensities. fMRI revealed significantly enhanced sound-evoked responses in the auditory cortex (AC) to 80 dB SPL tone bursts presented at 8 and 16 kHz. Sound-evoked responses in the inferior colliculus (IC) were also enhanced, but to a lesser extent. To confirm the main results, electrophysiological recordings of spike discharges from multi-unit clusters were obtained from the central auditory pathway. Salicylate significantly enhanced tone-evoked spike-discharges from multi-unit clusters in the AC from 4 to 30 kHz at intensities ≥60 dB SPL; less enhancement occurred in the medial geniculate body (MGB), and even less in the IC. Our results demonstrate for the first time that non-invasive sound-evoked fMRI can be used to identify regions of neural hyperactivity throughout the brain in an animal model of hyperacusis.

The Spectrum of Vestibular Migraine: Clinical Features, Triggers, and Examination Findings.

OBJECTIVE: To assess the ictal symptoms, interictal symptoms, psychiatric comorbidities, and interictal neuro-otologic examination findings in vestibular migraine (VM). METHODS: Retrospective chart review of 491 patients seen from August 2014 until March 2018 at a tertiary neurology referral center for vestibular disorders to identify patients fulfilling the 2012 VM criteria. RESULTS: One hundred and thirty-one patients (105 women) were identified. Mean age of VM onset was 44.3 (±13.7) years. Preceding the onset of vestibular symptoms, most had migraine (57.3%) and motion sickness (61.1%). It was common to have a family history of migraine (50.8%) and episodic vestibular symptoms (28.1%). Common ictal symptoms were triggered (visually induced and head-motion) and spontaneous vertigo, accompanied by photophobia and phonophobia (118/131 [90.1%] patients), nausea (105/131 [80.2%] patients), aural symptoms (79/131 [60.3%] patients), and headache (65/131 [49.6%] patients). Interictally, many experienced visually induced (116/131 [88.6%] patients), head-motion (86/131 [65.6%] patients), and persistent (67/131 [51.1%] patients) dizziness. Psychiatric comorbidities include anxiety (92/131 [70.2%] patients), depression (53/131 [40.5%] patients), insomnia (38/131 [29.0%] patients), phobic disorders (15/131 [11.5%] patients), and psychogenic disorders (11/131 [8.4%] patients). Common triggers were stress (52/131 [39.7%] patients), bright lights (35/131 [26.7%] patients), weather changes (34/131 [26.0%] patients), and sleep deprivation (34/131 [26.0%] patients). Interictal neuro-otologic examination was abnormal in 56/131 (42.7%), usually hyperventilation-induced, head-shaking-induced, vibration-induced, and positional nystagmus. The most common balance-test finding was impaired sharpened Romberg's test (22/130 [16.9%] patients). CONCLUSIONS: In this single center study, we found that VM typically affects women in their 40s, with a personal and family history of migraine. Typical ictal symptoms were triggered and spontaneous vertigo, associated with photophobia and phonophobia, nausea, aural symptoms, and headache. Interictal vestibular symptoms, comorbid psychiatric disorders, and non-specific interictal neuro-otologic findings were common.

Hyperacoustic hypoacusis: A new pontine syndrome-Case report.

We herein report a unique case of a lateral pontine demyelinating lesion presenting with unilateral sensorineural hearing loss and paradoxical ipsilateral hyperacusis. The association of unilateral hearing loss and ipsilateral hyperacusis is a rare manifestation of a central nervous system lesion. The paradoxical combination of these symptoms strongly suggests pontine dysfunction and prompts urgent neurological evaluation.

Do extant elephants have superior canal dehiscence syndrome?

CONCLUSION: X-ray CT of an Asian elephant's skull suggest that elephants do not have a labyrinthine 3(rd) mobile window. This excludes the concept that elephants benefit from enhancement of bone conducted vibration by an extra opening of the labyrinth. This finding does not, however, exclude that elephants use bone conducted hearing for seismic detection, nor that other species may use an extra labyrinthine opening for improved detection of seismic signals. OBJECTIVES: In man, a pathologic extra opening of the bony labyrinth causes altered hearing with supranormal bone conduction. Theoretically, this variation in auditory performance could be advantageous for detection of seismic waves. METHOD: The skull of an adult Asian elephant was examined by X-ray computed tomography to investigate whether a natural '3(rd) mobile window' mechanism for enhanced sensitivity of body sounds exist in elephants. RESULTS: Although the entire elephant's skull was otherwise broadly aerated, the labyrinth areas were surrounded by dense bone.