Table 4.

Endotype-specific clinical considerations.

Endotype (patient subgroup)	Laterality	Endotype frequency	Characteristics/considerations
ES hypoplasia (MD-hp patients)	Overall	23.6%	Specific radiological feature (VA bending angle ≥140°) Prognostic radiological screening possible Possible concomitant SSC dehiscence syndrome ES not visualizable for surgical ES enhancement/shunting (*)
	Unilateral	16.7%	Very low risk of developing bilateral MD (†) Most suitable for vestibular ablative therapy
	Bilateral	6.9%	Very high risk of developing bilateral MD Avoid performing vestibular ablative therapy (‡) Significant impact on auditory/vestibular function and quality of life must be expected
ES degeneration (MD-dg patients)	Overall	76.4%	Suitable for ES surgery if considered (§) Consider average higher frequency of vertigo symptoms, more severe vestibular hypofunction when establishing treatment Consider sequential imaging to rule out ES tumors if symptomatology increases over baseline fluctuations (||)
	Unilateral	72.2%	“Clinically silent” contralateral EH (19.2%) Unknown risk for progression to bilateral disease Increased risk to perform vestibular ablative treatment
	Bilateral	4.2%	Least frequent endotype, 4.2% of patients

^*Considering the anticipated low chance of intraoperatively identifying the operculum (25).

^(†)equal to the overall risk of developing MD with degenerative ES pathology in the general population [i.e., 0.15% based on the MD prevalence of 0.2% (26) and a prevalence of degenerative ES pathology of 76.4% among MD patients in the present study].

^(‡)upon initial presentation with clinically unilateral symptoms.

^(§)due to degenerative changes of extraosseous ES in these patients (6), we consider the rationale for ES surgery questionable. (||) according to Kirsh et al. (27). In MD-hp patients, ES hypoplasia sufficiently explains the etiology.