Advantages & limitations of imaging

Imaging is most valuable when the diagnosis is uncertain, when a dangerous cause must be excluded, or when surgery is being planned. In those settings it pays for its inconvenience.

• Lesion localisation. MRI distinguishes peripheral (schwannoma, labyrinthitis) from central (cerebellar infarct, MS plaque) pathology with consequences for management and prognosis.
• Surgical and procedural planning. Contrast-enhanced MRI defines schwannoma size and extent before microsurgery or radiosurgery; HRCT defines SSCD anatomy before plugging; both define vascular anatomy before endolymphatic sac surgery.
• Exclusion of life-threatening pathology. DWI-MRI is the test that catches small cerebellar and brainstem infarcts; CTA finds basilar occlusion and vertebral dissection. The downstream stroke pathway hinges on the imaging.
• Diagnostic clarity in atypical presentations. When the bedside is ambiguous, imaging shifts probabilities and frees the clinician to commit to a management plan.
• Substrate for “functional” disorders. fMRI and PET work in PPPD and MdDS provides the biological substrate that legitimises CBT + vestibular rehabilitation as appropriate therapy.

The single largest clinical benefit of getting the right imaging in a dizzy patient is the avoidance of missed posterior-circulation stroke. Small cerebellar infarcts can present as isolated vertigo, and HINTS combined with DWI / CTA is the practical pathway to catch them.1,4

Imaging is not a universal solvent. In the wrong clinical context it adds cost, radiation, anxiety and incidental findings without changing what happens next.

• Cost and access. Out-of-hours MRI is the practical bottleneck in most centres. CT is fast and available but answers fewer questions in vertigo.
• Radiation. CT — particularly serial CTA — accumulates dose that matters in paediatric and young-adult patients.
• False negatives. Early-window DWI misses ~12% of small posterior-fossa strokes in the first 24–48 hours; a single negative scan does not exclude infarction.2
• False positives. Thin bone over the superior canal can be mis-called as SSCD on axial-only review; incidental small vestibular schwannomas appear in a small but non-trivial fraction of contrast MRIs.
• Interpretive variability. Subtle perilymph fistula, intracochlear schwannoma and early labyrinthitis findings depend on radiologist experience and explicit clinical context on the request.
• Low yield in BPPV. Classic posterior-canal BPPV is a clinical diagnosis treated by Epley.3Imaging adds nothing in routine cases and risks incidental findings that derail the clinical narrative.

The discipline: imaging is requested with a clinical question in mind, not as a reflex. Every request should state the syndrome, the differential, and the management decision the answer will support. Done well, imaging is a consequential tool; done as a default, it crowds the radiology list and rarely changes outcomes.