By history, both affected siblings achieved normal psychomotor development including acquisition of speech and language. In both, hearing loss was first noted at the age of 14 years (together with bilateral tinnitus after a severe influenza infection in II:1), but probably occurred earlier. The earliest audiology reports that were available to us referred to investigations performed at the age of 17 years (patient II:1) and 24 years (patient II:4), respectively, both showing moderate-to-severe bilateral neurosensory hearing impairment. Both patients had normal ear canals and tympanic membranes and experienced progressive hearing loss, leading to severe (right) to profound (left) hearing loss. Patient II:1 complained about mild imbalance. A high-resolution CT of the temporal bones and the brain in II:1 was normal. Both patients used hearing aids in the past and received cochlear implants around the age of 35 years.
Nyctalopia became apparent at the age of 18 years in both patients. II:1 underwent sequential bilateral cataract surgery at the age of 26 and 29 years, respectively. Best visual acuity was 20/25 (6/9) bilaterally at the age of 30 years. Dark adaptation, color vision, and ERG were moderately abnormal compared to her brother. Ten years later, at the age of 40 years, funduscopy revealed peripheral retinal changes with fine macular pigmentary changes and best corrected visual acuity of 20/200 (6/60). Last exam at the age of 55 years revealed best corrected visual acuity of 20/400 (6/120) for the right eye and counting fingers for the left eye, left esotropia, 20° of visual fields bilaterally, a cup-disc ratio of 0.9 bilaterally from glaucoma on topical therapy, and fine retinal spicules at the equator.
For II:4, examination records were available from the age of 23 years onward and gave similar results in both eyes. Best corrected visual acuity was 20/100 (6/30) with early posterior subcapsular cataract, vitreous degeneration, marked pallor of optic disc, marked narrowing of retinal vessels, and peripheral retinal pigmentation. Abnormal dark adaptation, constricted visual fields, markedly reduced ERG, and normal Farnsworth D-15 color test supported the clinical diagnosis of USH. Eye exam at the age of 38 years revealed best corrected visual acuity of finger counting at 2 m, moderate posterior subcapsular cataract, severe disc pallor and marked peripheral intraretinal bone spicules in both eyes.
At the most recent examination at the age of 50 years, vision was reduced to light perception on both eyes with moderate posterior capsular cataract, and medically controlled glaucoma. The macular region was atrophic with severe optic atrophy.
II:1 underwent neurological evaluation at the age of 53 years because of a four year history of gait imbalance and writing difficulties for three years. There was a history of tremor since the age of 19 years. Her examination revealed an ataxic gait with poor tandem walking. She had an action tremor with writing cramp and involuntary athetotic movements of her fingers. Her finger to nose exam, muscle tone, and deep tendon reflexes were normal with negative Babinski sign. Brain morphology was normal in a CT of the brain.
In both patients, examination of cranial nerves III, IV, and VI revealed normal eye movements without nystagmus (neither spontaneous nor gaze-induced). Slow pursuit was smooth and saccades were accurate. Trigeminal sensation, corneal reflexes and facial function were intact. In general, disease progression was similar in both cases.