Background: Ocular counter-roll (OCR) is an otolith-mediated vestibulo-ocular reflex that produces torsional rotation of the eyes in response to head tilt. Accordingly, measuring ocular torsion can provide an assessment of vestibular tone balance related to otolith function. This can be objectively quantified from fundus photographs using the disc-foveal angle (DFA). Because head tilt also physiologically alters ocular torsion through OCR, head position during fundus imaging may influence the measured DFA. Here, we examined this effect of head tilt and the resulting OCR on fundus-based measurements of ocular torsion. Methods: Ten healthy adults (age 28–45 y/o; 2 females) underwent bilateral fundus photography under three conditions: routine head placement, controlled upright (0°) positioning, and 10° lateral head tilt. Head orientation was continuously measured using a strap-mounted gyroscope. DFA was quantified from fundus images as the angle between the fovea–optic disc axis and horizontal meridian using ImageJ. Results: Mean DFA did not differ between standard and controlled head positioning (p = 0.23), although within-subject variability was greater with standard positioning (p = 0.020). In contrast, 10° head tilt significantly changed DFA (p < 0.01). Conclusions: Small, naturally occurring variations in head position do not significantly alter DFA but may increase measurement variability, whereas larger head tilts produce significant changes in DFA. Careful control of head position during fundus photography can improve the reliability of DFA measurements for assessment of otolith-ocular function.
Background: Vestibular migraine (VM) and benign paroxysmal positional vertigo (BPPV) frequently present with overlapping positional symptoms, making their differential diagnosis challenging. This study aimed to characterize positional vestibular manifestations in patients with suspected VM. Methods: In this observational study, 85 adult patients presenting with positional vertigo or dizziness in whom typical BPPV could not be demonstrated were evaluated. All patients underwent detailed clinical and neurotological assessment, videonystagmography, and standardized positional testing. Results: Definite VM was diagnosed in 51/85 patients (60.0%) and probable VM in 23/85 (27.1%), accounting together for 87.1% of the selected cohort. Positional nystagmus was documented in 52 patients (61.2%), of whom 38/52 (73.1%) showed at least one atypical characteristic. Pupillary Nystagmus (PNy) was detected in 61/85 patients (71.8%). Among 14 patients with an initially BPPV-like positional pattern, five responded to canalith repositioning maneuvers, whereas nine had persistent or recurrent symptoms requiring diagnostic reassessment. At 3 months, 66/74 patients (89.2%) with definite or probable VM reported marked overall clinical improvement, while complete resolution of positional vertigo or dizziness occurred in 49/74 (66.2%). Positional nystagmus resolved in 36/47 patients (76.6%) who had presented with this finding at baseline. Conclusions: VM should be considered in patients with recurrent positional vestibular symptoms when positional findings are atypical, variable, or inconsistent with a single semicircular canal disorder, particularly when repositioning maneuvers are ineffective. PNy may provide an additional supportive finding, although its diagnostic value requires validation in controlled studies. Treatment response may support the overall clinical interpretation but should not be regarded as an independent diagnostic criterion.
Background: Indoor mold exposure (IME) has been associated with nonspecific neurological symptoms, including dizziness, cognitive complaints, and fatigue. Whether environmental exposures related to damp indoor environments influence vestibular migraine (VM), a common cause of episodic vertigo involving interactions among vestibular and migraine-related pathways, remains unclear. Objective: To examine the overlap between vestibular symptoms reported in association with IME and those characteristic of VM, and to explore how this overlap may contribute to potential diagnostic misattribution when environmental factors are not adequately considered during clinical assessment. Methods: A hypothesis-driven narrative review was conducted using PubMed and Scopus, synthesizing evidence on VM, symptoms reported in association with IME, and potential biological mechanisms to explore potential explanations for overlapping vestibular symptoms and their implications for diagnostic misattribution. An illustrative clinical case was included to provide clinical context for the proposed hypothesis. Results: Findings identify overlapping vestibular symptoms between patients with VM and symptoms associated with IME. However, the available evidence is largely indirect, and no studies have directly investigated whether this symptom overlap contributes to diagnostic misattribution of VM. Conclusions: Evidence remains insufficient to establish diagnostic misattribution of VM in the context of indoor mold exposure. Environmental exposure history should be considered alongside established diagnostic criteria, and further research is needed to investigate this possibility.
Background/Objectives: Hearing assessment may be challenging in individuals of very advanced age when cognitive or physical limitations restrict participation in behavioural testing or access to clinic-based hearing care. This study evaluated the suitability of auditory steady-state responses (ASSRs) as a clinical method for assessing peripheral hearing in individuals of very advanced age by examining its agreement with pure-tone audiometry (PTA) thresholds and its feasibility in a home setting among individuals aged 88–95 years. Methods: Home visits were conducted for 91 individuals, of whom 71 completed the behavioural and electrophysiological test protocol and were included in the analyses. ASSR thresholds at 0.5, 1, 2, and 4 kHz were compared with corresponding PTA thresholds for the right and left ears. Agreement was assessed using Bland–Altman analyses, with differences within ±15 dB considered clinically acceptable. Reasons for unobtained ASSR thresholds were systematically recorded. The Mini-Mental State Examination (MMSE) was administered, and PTA–ASSR threshold differences were compared using a cut-off score of ≤26 for cognitive impairment. Results: ASSR thresholds were within ±15 dB of the corresponding PTA thresholds in 92% of right ears and 85% of left ears. Mean differences were close to 0 dB at most frequencies, although greater differences were observed at 0.5 and 1 kHz in the left ear. The mean ASSR test duration was 21.5 min. ASSR thresholds were unobtainable in 31% of PTA–ASSR comparisons, most commonly because of high rejection rates related to EEG and/or myogenic activity and participant discomfort. PTA–ASSR threshold differences did not differ significantly between MMSE groups (≤26 vs. >26). Conclusions: ASSR offers a promising alternative for hearing assessment in individuals of very advanced age who may have difficulty participating in behavioural testing. Furthermore, the results suggest that ASSR can be performed in home settings, including nursing homes and residential care facilities. Participant comfort and positioning are important for reducing muscular artefacts and improving measurement feasibility.
