Abstract
Purpose:
To evaluate peripheral vestibular deficits of the anterior, lateral or posterior semicircular canals in patients with Retinitis Pigmentosa (RP) and Usher Syndrome (USH) using the Video Head Impulse Test (VHIT) with Ulmer technique.
Methods:
12 patients, 4 male and 8 female (mean age 54 ± 14,7 years) were enrolled. We examined 24 eyes: 16 typical RP, 4 Usher Syndrome, 2 rod-cone dystrophy and 2 cone dystrophy. All patients underwent a complete ophthalmologic, audiologic and vestibular assessment. The ophthalmologic examination included measurement of best corrected visual acuity (BCVA) with Snellen visual acuity chart and conventional perimetry with the Humphrey Field Analyzer (SITA Standard, program 30-2 or 10-2, Goldmann size III stimuli). The audiologic and vestibular protocols included audiometry, caloric test, cervical vestibular evoked myogenic potential (cVEMPs), ocular vestibular evoked myogenic potential (oVEMPs) and VHIT.
Results:
Mean BCVA was 0,6 ± 0,5 logMAR. Humprey visual field showed a mean defect (MD) of -19,81 ± 11,25 dB for OD and -19,4 ± 11,65 dB for OS. At audiometry five patients showed bilateral hypoacusia (38,5%), one had age-related hearing loss (7,7%) and six presented (53,8%) normal audiometric curves. Caloric test was abnormal in four participants (30,8%): three showed hypo-excitability on both sides and one on one side only. In ten patients there were bilateral preservation of cVEMPs that was absent in only one (8,3%). The unilateral and bilateral absence of oVEMPs was diagnosed in one (7,7%) and two (15,4%) patients respectively. The VHIT wasn’t result reliable in two participants but in five there were a selective damage of semicircular canals: one patient with rod-cone and one with cone-dystrophy had an abnormal function of right and left superior semicircular canals; two with typical RP and one affected by Usher Syndrome presented, respectively, a right-sided deficit of the superior and posterior semicircular canals.
Conclusions:
The vestibular analysis with video-HIT didn’t demonstrate any selective alteration in patients with RP or USH. The test didn’t show any association between the genetic disorder and vestibular deficit. Neither RP mutated genes or Usher’s genes can be associated with the altered results obtained with the video-HIT.
Keywords: 696 retinal degenerations: hereditary •
758 visual fields •
584 low vision