Analysis of the data showed that dizziness and vertigo is not a sensitive predictive factor for diagnosis of posterior Fossa infarct. We can therefore conclude that dizziness is a vague symptom; in fact, many of the scans performed showed normal brain imaging and normal internal acoustic meatus. Only 3.90% of those without posterior Fossa infarcts had an infarct elsewhere in the brain. Most of the other patients (67.86) had normal imaging with no cause found for their symptoms. There was only 0.34% difference between diagnoses of new onset posterior and anterior circulation strokes underlying the fact that ‘posterior circulation symptoms’ of vertigo, ataxia, dizziness and vomiting are non-specific and cannot predict the aetiology.
Findings from this small study suggest that similar to Kabra’s research ‘Diagnostic yield and impact of MRI for acute ischaemic stroke in patients presenting with dizziness and vertigo’, Dix-Hallpike manoeuvres should be performed to distinguish peripheral and central aetiology since it is a good predictive value of posterior Fossa stroke. As the manoeuvre is such a simple bedside test, it should perhaps be used more in clinical practice to differentiate between aetiology rather than relying solely on ‘diagnostic’ scans [4]. In conclusion, this study suggests that clinical examination findings should be used to determine appropriateness of MRI scans rather than relying purely on patients’ reported symptoms of dizziness and vertigo. This is because such reported symptoms are often subjective and non-specific, and they also have a high negative predictive value with 67.86% of any pathology and 95.92% negative predictive value for presence of posterior Fossa infarct. Had case notes been available, it would be interesting to see the number of patients who had a full neurological examination prior to request for MRI.
Kabra et al., came to an alternative conclusion where the yield was 21% with diagnostic impact of MRI on management being 22% [4] meaning clinicians should have a low threshold for requesting MRI if patients exhibit these features. However, this research study would suggest that vestibular symptoms are non-specific for diagnosing posterior Fossa infarct given the low percentage of positive results amongst the large cohort in this study. The majority of MRI are normal (67%) and only 8% (anterior and posterior) infarct demonstrate stroke. In conclusion, this study suggests that clinical examination should take precedence over relying on MRI scans in patients with dizziness for a diagnosis.