Pitfalls in the diagnosis of acoustic neuroma

Diagnostic delays in vestibular schwannoma

OBJECTIVES

The literature on delays in vestibular schwannoma diagnosis is from the era before the routine use of magnetic resonance imaging. We evaluated such diagnostic delays and their impact on tumour size and on pre- and post-treatment morbidity, in a relatively recent patient series.

STUDY DESIGN

Retrospective review.

METHODS

A two-centre study was conducted, including 91 consecutive vestibular schwannoma patients diagnosed between 1992 and 2006. Data on the presenting symptom and the initial medical visit were obtained from primary care records completed at the time of the initial visit; data on the tumour and the clinical course were obtained from review of the hospital chart. Data on diagnostic delays were available for 59 patients.

RESULTS

The median patient, professional and total diagnostic delays were three, four and 14 months, respectively. Unilateral hearing loss as the presenting symptom predicted an lengthened total diagnostic delay. Diagnostic delay had no impact on the tumour size at time of diagnosis or on the pre- and post-treatment morbidity.

CONCLUSIONS

Delays in the diagnosis of vestibular schwannoma have shortened since the introduction of magnetic resonance imaging. Longer diagnostic delays do not seem to have significant consequences.

The investigation of acoustic neuroma

Gadolinium-enhanced magnetic resonance (GdMR) is the long awaited, easy and definitive investigation for imaging or excluding small acoustic neuromas. However, on the grounds of cost alone it is unrealistic to submit every patient with mild unilateral sensorineural deafness to GdMR. A screening regime is described which combines simple but effective imaging studies of the internal auditory meatus with clinical testing of vestibular function and objective audiometry. The 'two out of three positive' approach based on these tests has proved to be a reliable screening regime for selecting patients for GdMR.

A screening protocol used for the detection of acoustic neuromas: a clinical evaluation

Screening for acoustic neuromas in large numbers of patients in whom the possibility exists should effectively select out the small proportion who have a tumour, prior to more definitive but costly radiological scanning techniques. A suitable screening protocol has been suggested using a combination of caloric testing, tomography of the internal auditory meati and evoked response audiometry. The protocol was applied retrospectively from the records of 64 patients with proven acoustic neuromas and found to predict correctly the presence of a tumour in 97% of cases. It is concluded that this combination of investigations constitutes an effective method of screening patients in whom an acoustic neuroma confined to the 8th nerve is suspected. The great importance of early diagnosis is that the operative mortality and morbidity is much less when the tumour removed is small.