Incidence of Unilateral, High Frequency, Sensorineural Hearing Loss in Shunt Treated Hydrocephalic Children Ipsilateral to Shunt Placement

The purpose of this study was to investigate further the characteristics of hearing loss in ventriculoperitoneal (VP) shunted hydrocephalus. Twelve (VP) shunt treated hydrocephalus children participated in this study. The etiology of the hydrocephalus was either intraventricular hemorrhage or spina bifida. A recent neurological examination reported the shunt to be patent in each child. Audiometric examination included pure tone air conduction thresholds, tympanometry, contralateral and ipsilateral acoustic reflex thresholds and distortion product otoacoustic emissions (DPOAEʹs). A unilateral, high frequency, sensorineural hearing loss was found in the ear ipsilateral to shunt placement in 10 (83%) of the 12 shunt treated hydrocephalic children. No hearing loss was observed the ear contralateral to shunt placement. Based on the pure tone findings coupled with the decrease in DPOAE amplitude in the shunt ear, the hearing loss appears to be cochlear in nature. It is hypothesized that the cochlear hydrodynamics are disrupted as the result of fluid pressure reduction within the perilymph being transmitted via a patent cochlear aqueduct as a reaction to the reduction of CSF via a patent shunt. In addition, a concomitant brainstem involvement is evidenced in the ART pattern possibly produced by the paten shunt draining CSF from the subdural space resulting in cranial base hypoplasia