Recovery Nystagmus in Vestibular Neuritis with Minimal Canal Paresis. Clinical Observation and Interpretation

Recovery nystagmus in vestibular neuritis patients is a reversal of spontaneous nystagmus direction, beating towards the affected ear, observed along the time course of central compensation. It is rarely registered due either to its rarity as a phenomenon per se, or to the fact that it is missed between follow-up appointments. The aim of the manuscript is to describe in detail a case of recovery nystagmus found in an atypical case of vestibular neuritis and discuss pathophysiology and clinical considerations regarding this rare finding. A 26-year-old man was referred to our Otorhinolaryngology practice reporting “dizziness” sensation and nausea in the last 48 h. Clinical examination revealed left beating spontaneous nystagmus (average slow phase velocity aSPV 8.1°/s) with absence of fixation. The head impulse test (H.I.T.) was negative. Cervical vestibular evoked myogenic potentials (cVEMP) and Playtone audiometry (PTA) were normal. Romberg and Unterberger tests were not severely affected. A strong directional preponderance to the left was found in caloric vestibular test with minimal canal paresis (CP 13%) on the right. The first follow-up consultation took place on the 9th day after the onset of symptoms. Right beating weak (aSPV 2.4°/s) spontaneous nystagmus was observed with absence of fixation, whereas a strong right directional preponderance (DP) was found in caloric vestibular test. A brain MRI scan was ordered to exclude central causes of vertigo, which was normal. The patient was seen again completely free of symptoms 45 days later. He reported feeling dizzy during dynamic movements of the head and trunk for another 15 days after his second consultation. The unexpected observation of nystagmus direction reversal seven days after the first consultation is a typical sign of recovery nystagmus. Recovery nystagmus (RN) is centrally mediated and when found, it should always be carefully assessed in combination with the particularities of vestibular neuritis.

The Relationship Between Sudden Sensorineural Hearing Loss, Vestibular Neuritis, and Infection With COVID-19

Introduction: This study aimed to investigate the relationship between sudden sensorineural hearing loss, vestibular neuritis, and infection with COVID-19. Materials and Methods: In this study, a total of 56 Iranians (32 females and 24 males) with a Mean±SD age of 45.12±14 years were studied in Tehran City, Iran. Individuals diagnosed with Sudden Sensorineural Hearing Loss (SSNHL) or vestibular neuritis based on definitive diagnostic criteria were included in the study. The methodology comprised four sections of underlying Sudden Hearing Loss,, auditory and vestibular inspection, SARS-CoV-2 Reverse Transcription-Polymerase Chain Reaction (RT-PCR) test, and statistical analysis. Also, the videonystagmography test was used in participants with vertigo to diagnose vestibular neuritis. Pure tone audiometry confirmed SSNHL in some patients with a complaint of hearing loss. Furthermore, tuning fork, Rinne and Weber tests were also performed. Results: The results of SARS-CoV-2 RT-PCR in 56 subjects showed that eight subjects (22.2%) with vestibular neuritis and two with SSNHL (10%) had a positive RT-PCR test. The Chi- square and Fisher exact-tests with a 95% confidence interval revealed no statistically significant (P>0.05) relationship between COVID-19 infection and vestibular neuritis or SSNHL. Conclusion: The present study showed no statistically significant relationship between audiovestibular disorders and positive SARS-CoV-2 RT-PCR test. However, the possibility of this relationship cannot be ruled out, and there is a need for studies with larger sample sizes.

Association Analysis of HIMP and SHIMP Quantitative Parameters in Patients With Vestibular Neuritis and Healthy Participants

Background: The Head Impulse Paradigm (HIMP) and Suppression Head Impulse Paradigm (SHIMP) are objective, quantitative methods that directly test the vestibulo-ocular reflex (VOR) and are increasingly becoming a standard in evaluating patients with vestibular disorders.Objective: The main objective was to assess the correlations between HIMP and SHIMP parameters in patients with superior vestibular neuritis (VN) and healthy participants. Additionally, the correlations between the parameters of each method were analyzed.Methods: A retrospective cohort, non-randomized study was designed. HIMP and SHIMP were performed on 40 patients with VN and 20 healthy participants (40 ears). HIMP and SHIMP parameters were measured and calculated. Pearson's or Spearson's correlations were used to establish the associations among them.Results: A strong positive correlation was found between HIMP and SHIMP gain (Pearson's r = 0.957, p = 0.000), while strong negative correlations were detected between HIMP and SHIMP saccade amplitudes (r = −0.637, p = 0.000) and percentages of overt saccades (r = −0.631, p = 0.000). In HIMP, strong and moderate positive correlations were identified between gain and saccade amplitude (R2 = 0.726, p = 0.000) and gain and saccade percentage (R2 = 0.558, p = 0.000), respectively. By contrast, an extremely weak positive correlation was observed between gain and latency (R2 = 0.053, p = 0.040). In SHIMP, strong and moderate positive correlations were found between gain and saccade percentage (R2 = 0.723, p = 0.000) and gain and saccade amplitude (R2 = 0.525, p = 0.000), respectively, but no correlation was detected between gain and latency (R2 = 0.006, p = 0.490).Conclusions: HIMP and SHIMP-related parameters were highly correlated (inter-method). Within each method (intra-method), moderate to strong correlations in VOR assessment were observed. These results further contribute to our understanding of the relationship between HIMP and SHIMP as well as to the diagnosis.

Histamine receptors in GtoPdb v.2021.3

Histamine receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Histamine Receptors [80, 173]) are activated by the endogenous ligand histamine. Marked species differences exist between histamine receptor orthologues [80]. The human and rat H3 receptor genes are subject to significant splice variance [12]. The potency order of histamine at histamine receptor subtypes is H3 = H4 > H2 > H1 [173]. Some agonists at the human H3 receptor display significant ligand bias [182]. Antagonists of all 4 histamine receptors have clinical uses: H1 antagonists for allergies (e.g. cetirizine), H2 antagonists for acid-reflux diseases (e.g. ranitidine), H3 antagonists for narcolepsy (e.g. pitolisant/WAKIX; Registered) and H4 antagonists for atopic dermatitis (e.g. adriforant; Phase IIa) [173] and vestibular neuritis (AUV) (SENS-111 (Seliforant, previously UR-63325), entered and completed vestibular neuritis (AUV) Phase IIa efficacy and safety trials, respectively) [216, 8].