Tolosa–Hunt Syndrome: A Review of Diagnostic Criteria and Unresolved Issues

Purpose: To review the diagnostic criteria for Tolosa–Hunt syndrome (THS) and utility of recent modifications. Methods: We searched PubMed for keywords Tolosa Hunt and magnetic resonance imaging. We compared the three editions of International Classification of Headache Disorders and isolated case reports and case series with the assessment of cavernous internal carotid artery (ICA) caliber to find the prevalence of vascular anomalies. We also evaluated cases of THS with the involvement of extracavernous structures and the possible role of idiopathic hypertrophic pachymeningitis (HP). Cases diagnosed falsely as THS were also reviewed for the presence of atypical features and relevance of criterion D. We assessed nonconforming cases (those with normal neuroimaging benign THS) and idiopathic inflammatory orbital pseudotumor (IIPO). Results: Vascular abnormalities were found in 36.36% of THS cases. Benign THS may also show changes in ICA caliber. Evidence suggestive of idiopathic HP could be found in 57% of cases with the involvement of extracavernous structures, such as facial nerve and pituitary gland. Both THS and IIPO are steroid‑responsive pathologies with similar clinical and radiological features. False‑positive diagnosis of THS results from early labeling, based solely on clinical features and symptom resolution after steroid therapy. Conclusions: Benign THS may be a result of limitation of resolution of available neuroimaging technique or early testing. Early and late vascular changes can be seen in both THS and its benign variant; some of them are not innocuous. THS may be considered a type of focal idiopathic HP. IIPO may represent an anterior variant of THS. In the absence of histopathological diagnosis, steroid‑induced resolution of symptoms should be confirmed radiologically and followed‑up.