The impedance bridge and ENG controlled fistula test: results in children with unilateral deafness and comparison with normal controls.

The diagnosis of a perilymph fistula is normally made on clinical grounds. Thus in most cases suspicion is raised by the clinical history and the presence of a fistula confirmed at operation. In children such fistulae may be relatively silent and the diagnosis difficult to establish. This paper reports the results of using an impedance bridge and ENG-controlled fistula test in the routine screening of 24 children with unilateral sensorineural deafness, and compares the results obtained to those found from testing 21 normal and asymptomatic children of comparable age and sex. These tests have shown that fistula testing may mimic a previously recorded gaze or positional nystagmus and hence give false positive results. In the routine testing of patients with deafness only 1 subject had nystagmus invoked by fistula testing alone, and in this case it was obvious from all other criteria that no fistula was present. The conclusions drawn are that the method is prone to error if spontaneous, gaze and positional nystagmus are not recorded and that in routine clinical use the test may produce erroneous results. New criteria for the interpretation of the test in children are suggested, but it seems that the best means of diagnosis still remains an accurate history and a readiness to explore the ear to confirm the diagnosis.