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The impedance bridge and ENG controlled fistula test: results in children with unilateral deafness and comparison
Insights
Diagnosing perilymph fistulas in children can be challenging. New tests show potential but may yield false positives, emphasizing the continued importance of clinical history and surgical exploration for accurate diagnosis.
Area of Science:
- Otolaryngology
- Pediatric Audiology
- Neurosurgery
Background:
- Perilymph fistulas are typically diagnosed clinically, relying on patient history and surgical confirmation.
- Diagnosing perilymph fistulas in pediatric patients presents unique challenges due to potentially subtle presentations.
- Sensorineural hearing loss in children necessitates thorough etiological investigation.
Purpose of the Study:
- To evaluate the efficacy of an impedance bridge and ENG-controlled fistula test in screening children with unilateral sensorineural deafness.
- To compare the diagnostic accuracy of these tests against a control group of normal, asymptomatic children.
- To identify potential pitfalls and refine diagnostic criteria for perilymph fistulas in pediatric populations.
Main Methods:
- Routine screening using an impedance bridge and ENG-controlled fistula test was performed on 24 children with unilateral sensorineural deafness.
- A control group of 21 age- and sex-matched normal, asymptomatic children underwent the same testing procedures.
- Spontaneous, gaze, and positional nystagmus were recorded to differentiate true fistula signs from artifacts.
Main Results:
- Fistula testing can mimic pre-existing nystagmus, leading to potential false-positive results.
- In routine screening of deaf children, only one subject showed nystagmus solely from fistula testing, with other criteria ruling out a fistula.
- The impedance bridge and ENG-controlled fistula test are prone to error if baseline nystagmus is not meticulously recorded.
Conclusions:
- The impedance bridge and ENG-controlled fistula test require careful interpretation, especially when baseline nystagmus is present.
- Accurate patient history remains a critical component in diagnosing perilymph fistulas in children.
- Surgical exploration continues to be the gold standard for confirming the diagnosis of perilymph fistulas.
Abstract:
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.