The clinical utility of high resolution magnetic resonance imaging in the diagnosis of giant cell arteritis: a critically appraised topic.

BACKGROUND: Giant cell arteritis (GCA) is a relatively common form of systemic vasculitis, known for its predisposition to affect extracranial branches of the carotid artery and associated potential for causing visual loss and stroke. Neurologists need to be vigilant for this disorder, diagnose it early, and institute effective corticosteroid therapy. The differential diagnosis can be broad. Unfortunately, all clinical and laboratory features of GCA are limited by either low sensitivity or low specificity. Temporal artery biopsy remains the gold standard, but it has its own limitations. Noninvasive imaging techniques, like magnetic resonance imaging (MRI), may be capable of detecting the occurrence of GCA. OBJECTIVE: How useful is high resolution MRI as a diagnostic test in establishing the diagnosis of GCA? METHODS: We addressed the question through development of a structured critically appraised topic. Participants included consultant and resident neurologists, clinical epidemiologists, medical librarian, and clinical content experts in the field of neuroradiology, rheumatology, and vascular neurology. Participants started with a clinical scenario and a structured question, devised search strategies, located and compiled the best evidence, performed critical appraisals, synthesized the results, summarized the evidence, provided commentary, and declared bottom-line conclusions. RESULTS: A single study which assessed the diagnostic value of MRI against a reference standard in GCA was appraised. For the MRI, the estimated sensitivity was 81% (95% CI 67-95), specificity was 97% (91-100), positive likelihood ratio (LR) was 26.6 (95% CI 3.8-184.8), negative LR was 0.20 (95% CI 0.10-0.41). The study exhibited several methodological weaknesses which interfered with its validity. CONCLUSIONS: The specificity and positive LR of high resolution MRI are sufficiently high that a positive MRI combined with other clinical and laboratory data consistent with GCA may be useful in diagnosing GCA. Given the relatively low sensitivity of the test, a negative MRI would not be sufficient to rule out the diagnosis of GCA.

Cogan's syndrome: an audiovestibular, ocular, and systemic autoimmune disease.

Cogan's syndrome is an immune-mediated systemic disorder characterized by ocular and audiovestibular inflammation. Although interstitial keratitis in the absence of an infectious cause is the classic form of eye involvement, other nonspecific inflammatory eye diseases can also occur, often making prompt diagnosis of the underlying disease challenging. The audiovestibular disease is difficult to treat and can lead to profound hearing loss. A poor outcome, especially complete hearing loss, can sometimes be prevented through a timely recognition and initiation of glucocorticoid therapy at the onset of the disease.

Treatment of giant cell arteritis using induction therapy with high-dose glucocorticoids: a double-blind, placebo-controlled, randomized prospective clinical trial.

OBJECTIVE: Glucocorticoid (GC) therapy for giant cell arteritis (GCA) is effective but requires prolonged administration, resulting in adverse side effects. The goal of the current study was to test the hypothesis that induction treatment with high-dose pulse intravenous (IV) methylprednisolone permits a shorter course of therapy. METHODS: Twenty-seven patients with biopsy-proven GCA were enrolled in a randomized, double-blind, placebo-controlled study to receive IV methylprednisolone (15 mg/kg of ideal body weight/day) or IV saline for 3 consecutive days. All patients were started on 40 mg/day prednisone and followed the same tapering schedule as long as disease activity was controlled. The numbers of patients with disease in remission after 36, 52, and 78 weeks of treatment and taking

The utility of positron emission tomography in the evaluation of autoimmune hearing loss.

OBJECTIVE: To evaluate positron emission tomography as an imaging tool in the diagnosis, evaluation, and management of autoimmune inner ear disease. BACKGROUND: Autoimmune inner ear disease is a form of cochleovestibular disease associated with variable hearing loss and vertigo for which no reliable diagnostic tests are available. METHODS: Pilot study of 10 patients with autoimmune inner ear disease and 5 sex-matched and age-matched control subjects without any history of autoimmune inner ear disease, who underwent limited positron emission tomography of the inner ear. Five patients with new or active autoimmune inner ear disease underwent serial positron emission tomography before and after 4 to 6 weeks of a high-dose tapering course of prednisone. The subjects had cranial magnetic resonance imagining, audiometric and vestibular studies, and heat-shock protein (HSP-70) measurements. Reading of the positron emission tomography scans was blinded. RESULTS: Positron emission tomography was normal in 4 of 5 normal control subjects and abnormal in 1 with normal audiometric and vestibular studies and positive HSP-70. Of patients with established and stable autoimmune inner ear disease, 4 of 5 had no positron emission tomography abnormalities and negative HSP-70, and the one with abnormal positron emission tomography shortly thereafter manifested clinically active disease. Of the 5 patients with active autoimmune inner ear disease monitored serially, 4 had an initial abnormal positron emission tomography in at least one ear, which became normal in all but 1 patient after therapy. HSP-70 correlated with disease activity. Only 1 patient with clinically active autoimmune inner ear disease had a normal positron emission tomography before and after therapy (the HSP-70 was positive before therapy and negative after the therapy). CONCLUSIONS: Positron emission tomography, especially when combined with HSP-70 determination, may be a useful technique for assessing disease in patients with autoimmune inner ear disease.