Appropriateness of MRI IAM referrals for investigation of Tinnitus

Audit of the appropriateness of MRI IAM referrals in patients presenting with tinnitus and the subsequent imaging investigation carried out.

Increased availability and easy access to MRI has led to a steady increase in imaging requests for patients with tinnitus. Clinical data provided does not always specify the type of tinnitus (whether pulsatile or non-pulsatile), and all cases are referred for MRI of the IAM as a screening test for vestibular schwannoma.

Although to date there is no official UK guidance published regarding which imaging modality to choose in such cases, the RCR has cited the ACR Appropriateness criteria and Australian Diagnostic Imaging Pathways in its iRefer guidelines. These both indicate that distinction between types of tinnitus determines the most appropriate imaging study: for pulsatile tinnitus, it is contrast-enhanced CT of the petrous bone, upper neck and posterior fossa, while non-pulsatile tinnitus should be investigated by MRI. There is additional literature in agreement with this, stating that pulsatile and non-pulsatile tinnitus have separate imaging pathways based on the most common underlying pathologies, if any.  

Pulsatile tinnitus is usually due to a vascular abnormality or a middle ear tumour and therefore contrast enhanced CT is the study of choice. Non-pulsatile tinnitus is mostly due to systemic causes (such as hyperdynamic circulation) or non-treatable structural causes (such as vascular loops near the internal auditory canal), and very rarely due to vestibular schwannoma, which is best diagnosed by MRI. NICE is in the process of producing guidelines regarding tinnitus, this is to be published in 2020.

The standard: 

Imaging requests should clearly state:

   a-Type of tinnitus (whether pulsatile or non-pulsatile),

   b-Type of imaging study based on tinnitus type: either contrast-enhanced CT of the head or MRI of  the internal auditory meatuses.

Target: 

100%

Indicators: 

Percentage of imaging requests for tinnitus which do not specify its type (pulsatile/non-pulsatile). 

Type of imaging study requested and then performed

Data items to be collected: 

1. list of patients who have been referred for MRI IAM stating ‘tinnitus’ in the clinical information

2. type of imaging study requested.

3. type of imaging study undertaken - including detail of cases where CT was performed rather than MRI as requested as radiologist deemed CT more appropriate, or vice versa.

Suggested number: 

100 patients

1. Discuss audit results with local radiologists and the referring clinicians.
2. Identify the cases in which the RCR iRefer guidelines were not followed and the outcome of their imaging.
3. Consider further education for the referrers is required and/or modify MRI vetting process to decline requests not meeting distinction criteria that would enable the most appropriate imaging to be selected.
4. Use of rules in electronic requesting or clinical decision support systems.

RIS access

Data search: 1 hour

Data analysis: 2 - 3 hours

Report writing: 1  hour

1. RCR iRefer guidelines: Making the best use of clinical radiology, version 8.0.1.  E02 Sensorineural hearing loss and other inner ear symptoms. https://www.irefer.org.uk/guidelines

2. ACR Appropriateness Criteria – USA 2017. https://acsearch.acr.org/docs/3094199/Narrative/

3. Diagnostic Imaging Pathways – Tinnitus. Australia, January 2012.  http://www.imagingpathways.health.wa.gov.au/index.php/imaging-pathways/ear-nose-throat/tinnitus

4. S Vattoh et al.  A Compartment-Based Approach for the Imaging Evaluation of Tinnitus. AJNR Am J Neuroradiol 31:211–18

5. S Connor et al. Diagnostic yield of MRI for audiovestibular dysfunction using contemporary referral criteria: correlation with presenting symptoms and impact on clinical management. Clinical Radiology (2009) 64, 156-163

6. Pegge et al. Pulsatile Tinnitus: Differential Diagnosis and Radiological Work-Up. Curr Radiol Rep (2017) 5:5

7. Hoang JK, Loevner LA. Evaluation of Tinnitus and Hearing Loss in the Adult. 2020 Feb 15. In: Hodler J, Kubik-Huch RA, von Schulthess GK, editors. Diseases of the Brain, Head and Neck, Spine 2020–2023: Diagnostic Imaging [Internet]. Cham (CH): Springer; 2020. Chapter 15.

8. Tunkel DE, Bauer CA, Sun GH, et al. Clinical Practice Guideline: Tinnitus. Otolaryngol Head Neck Surg 2014, 151(2S) S1–S40.

9. Kircher ML, Standring RT, Leonetti JP. Neuroradiologic assessment of pulsatile tinnitus. J Otolaryngol Head Neck Surg. 2008;139(Suppl):144.

10. Mattox DE, Hudgins P. Algorithm for evaluation of pulsatile tinnitus. Acta Otolaryngol. 2008;128:427–31.

11. Joustra J, et al. Richtlijn tinnitus. Nederlandse Vereniging voor Keel–Neus–Oorheelkunde en Heelkunde van het Hoofd Halsgebied. 2016.

Nada Nakhla

Co-authors

Janki Patel