Vestibular myogenic potentials evoked by air-conducted stimuli at safe acoustic intensity levels retain optimal diagnostic properties for superior canal dehiscence syndrome

Figures & data

Table 1. Diagnostic criteria for SCDS.

Key symptoms

Vestibular hypersensitivity to loud sounds or vibrations Autophony and hearing hypersensitivity to internal sounds or vibrations

Key findings

Eye movements or nystagmus aligned with the affected superior semicircularcanal evoked by loud sound (Tullio phenomenon) or pressuring (Hennebert sign) Enhanced cVEMP response to sound (17) Air bone gap at 250-500 Hz ≥25 dB HL with normal middle ear function 256 Hz tuning fork at the ankle distinctly heard in one ear Temporal bone CT scans, reformatted on the plane of the superior semicircular canal, indicating dehiscence of the superior semicircular bony canal.

In the presence of suggestive anamnesis (a and/or b), the clinical diagnosis of SCDS is confirmed when two or more of key findings, including at least the number 5, are fulfilled. In the presence of the key findings 1 and/or 2, the SCDS diagnosis can be considered certain, otherwise probable.

Figure 1. Case/control distribution of cVEMP-corrected amplitude for the three tested frequencies. Box plots indicating the median and interquartile range. o: outliers.

Figure 2. Case/control distribution of oVEMP amplitude (µVolts) for the three tested frequencies. Box plots indicating the median and interquartile range. o: outliers.

Table 2. Summary statistics cVEMP.

Corrected amplitude cVEMP		Median	Min	Max	IQR	Cases/controls difference	Standard error	Relative standard error (%)	p
ACcVEMP500Hz	Controls	0.2	0.0	0.3	0.2	1.6	0.2	15.1%	<.0001
	SCDS	1.7	0.5	3.6	0.7
ACcVEMP1000Hz	Controls	0.1	0.0	0.4	0.2	1.3	0.2	13.6%	<.0001
	SCDS	1.6	0.4	2.0	1.1
ACcVEMP2000Hz	Controls	0.1	0.0	0.4	0.3	1.0	0.2	21.8%	.0001
	SCDS	1.1	0.3	2.0	1.3

Table 3. Summary statistics oVEMP.

Amplitude oVEMP (µVolts)		Median	Min	Max	IQR	Cases/controls difference	Standard error	Relative standard error (%)	p
ACoVEMP500Hz	Controls	1.2	0.1	3.1	1.5	23.0	4.8	20.9	<.0001
	SCDS	25.9	5.4	51.0	26.2
ACoVEMP1000Hz	Controls	0.7	0.3	2.2	0.7	9.9	3.0	30.1	.0021
	SCDS	8.0	0.0	33.9	10.0
ACoVEMP2000Hz	Controls	1.0	0.3	1.8	0.6	12.0	4.1	34.5	.0064
	SCDS	7.9	2.2	45.6	12.9