Head and Neck ImagingGusher
jet-like outflow of perilymphatic fluid from the oval window after fenestration or removal of the footplate of the
stapes. When the flow is less pronounced, the term 'oozer' is used. Only the first few ml are perilymph, the remainder of the fluid is cerebrospinal fluid.
A gusher or oozer occurs only rarely in ears with normal cochlear function, but is much more frequently encountered in ears with congenital hearing loss. In these ears, there is an abnormally large connection between the subarachnoid and perilymphatic spaces. The majority of cases originate from defects in the partition between the internal auditory canal and the inner ear, allowing a relatively wide communication. Perineural leakage around the facial nerve at the lateral end of the internal auditory canal has also been reported. Abnormal patency of the cochlear aqueduct (without radiologically visible dilatation) may be a reason for the development of an oozer.
The possibility of a peroperative gusher can be predicted from a preoperative CT study of the ear; patients with a wide communication between the internal auditory canal and inner ear are at risk. Also, see modiolus anomalies.
RH