PMC8220896_01
Horizontal videonystagmography (VNG) recording of the left eye showing the congenital nystagmus looking to the right (upward), to the center, and to the left (downward) (A). vHIT superimposed head [right: red; left: blue] and eye [green] velocity records in degrees/second (y axis) vs. time in ms (x axis) during HIMP trials for each semicircular canal, including mean values for VOR gain; the "Spontaneous Nystagmus" check box was not selected (B).
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F1
Gaze to the left showed a much less evident irregular pseudopendular left beating nystagmus (Figure 1A). The first HIMP protocol (Figure 1B) was performed without selecting the check box "Spontaneous Nystagmus" (SN not selected). Cervical vestibular-evoked myogenic potentials (cVEMPs) were normal (Supplementary Figure 1).
Timetable including the clinical information obtained during patient visits. PMH, past medical history; AMI, acute miocardial infarction; T1D, type 1 diabetes; CN, congenital nystagmus; Sx, symptoms; Dx, diagnosis; PMS, previous medical studies; N, normal; Tx, treatment; PE, physical examination; SN off, HIMP/SHIMP protocol performed without selecting the check box "Spontaneous nystagmus"; SN on, HIMP/SHIMP protocol performed selecting the check box "Spontaneous nystagmus"; LSCCs, lateral semicircular canals (SCCs); ASCC, anterior SCC; CDP, computerized dynamic posturography; Rec, recommendations.
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F2
Computerized dynamic posturography (CDP) showed a vestibular pattern with visual dysfunction, average stability of 63%, hip-strategy movements, and center-of-gravity alignment displaced forward with falls in conditions 5 and 6 (Supplementary Figures 2A,B). As shown in Figure 2, the patient had follow-up visits at 1, 2, 4, and 6 months, including DHI and physical examination. CT scan were normal. Customized maintenance exercises were advised if needed (Figure 2). His self-report and subjective and objective outcome measures indicated appreciable improvement during follow-up (Figure 2).
vHIT comparative superimposed head [right: red; left: blue] and eye [green] velocity in degrees/second (y axis) vs. time in ms (x axis), during HIMP trials of both lateral SCCs and of the R anterior SCC including VOR mean gain values, obtained at the 1st visit and at the 1st and 2nd month of follow-up with DHI scores (right column); "Spontaneous Nystagmus" check box not selected (A). Similar vHIT comparative superimposed head and eye velocity in degrees/second (y axis) vs. time in ms (x axis) during SHIMP trials obtained at the 1st and 2nd month of follow-up with DHI scores (right column); "Spontaneous Nystagmus" check box not selected (B).
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F3
The loss was mild at high frequencies in the right ear and mild to moderate in the middle-to-high frequency range for the left ear, compatible with presbycusis (Supplementary Figure 3). HIMP test results for both lateral SCCs performed at 1 and 2 months of follow-up and with calibration are shown in Figure 3A, together with those from the first visit (to allow for comparison along follow-up). Mean VOR gain of the R anterior SCC at 1 month of follow-up improved from 0.61 (first visit) to 0.68 (normal age-range values), with 15% overt saccades (100% on the initial visit) (Figure 3A); at month 2, the mean gain was 0.72 with no presence of saccades (Figure 3A). At month 1 and 2, mean VOR gain in both posterior and in the L anterior SCCs were within the normal range for the patient's age, and no refixation saccades were found (data not shown in Figure 3A). At 2 months of follow-up, lateral HIMP trials (SN selected) (Figure 4A) showed similar mean VOR gain values (0.3 to the left and 0.31 to the right) as with SN not selected (Figure 3A), with 5% of refixation overt saccades identified to the left and 30% to the right. SCC showed a mean VOR gain that was within the normal values for the patient's age (Supplementary Table 1), without refixation saccades. SHIMP trials at 2 months of follow-up (Figure 4B) also revealed similar mean VOR gain values (0.29 to the left and 0.28 to the right) in both vHIT conditions (Figure 3B), without anticompensatory saccades.
vHIT comparison of superimposed head [right: red; left: blue] and eye [green] velocity expressed in degrees/second (y axis) vs. time in ms (x axis) during HIMP trials of both lateral SCCs with the "Spontaneous Nystagmus" check box selected. Included are mean VOR gain values obtained at 2 months of follow-up (A). Similar vHIT comparison of superimposed head and eye velocity in degrees/second (y axis) vs. time in ms (x axis) during SHIMP trials; "Spontaneous Nystagmus" check box selected. Included are mean VOR gain values obtained at 2 months of follow-up (B).
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F4
Time series records for vHIT recording of all six canals vHIT recording timeseries are included as Supplememtary Material together with the impulse rejection/aceptance rate (Supplementary Figures 4-7). At 2 months of follow-up, lateral HIMP trials (SN selected) (Figure 4A) showed similar mean VOR gain values (0.3 to the left and 0.31 to the right) as with SN not selected (Figure 3A), with 5% of refixation overt saccades identified to the left and 30% to the right. SCC showed a mean VOR gain that was within the normal values for the patient's age (Supplementary Table 1), without refixation saccades. SHIMP trials at 2 months of follow-up (Figure 4B) also revealed similar mean VOR gain values (0.29 to the left and 0.28 to the right) in both vHIT conditions (Figure 3B), without anticompensatory saccades.