The time sequence of brain MRI findings in spontaneous intracranial hypotension

Objectives: To investigate the time sequence of brain magnetic resonance imaging findings of spontaneous intracranial hypotension. Methods: We retrospectively reviewed the medical records and brain magnetic resonance imaging findings of consecutive patients with spontaneous intracranial hypotension hospitalized between January 2007 and December 2017. Patients were divided into quartiles based on intervals between initial spontaneous intracranial hypotension symptom onset and brain magnetic resonance imaging scan. Six categorical and five continuous brain magnetic resonance imaging findings were assessed, including venous distension sign, enlarged pituitary gland, diffuse pachymeningeal enhancement, mid-brain pons deformity, subdural fluid collection, flattening of pons, midbrain-pons angle, descent of cerebral aqueduct, mamillopontine distance, distance of suprasellar cistern, and distance of prepontine cistern. In addition, we also calculated the neuroimaging scores with a score ≥5 classified as ‘high probability of spontaneous intracranial hypotension' and a score ≥3 as ‘intermediate-to-high probability.' Then, we analyzed the linkage between the onset-neuroimaging interval and brain magnetic resonance imaging findings, as well as different neuroimaging scores. Results: A total of 173 patients (57 males and 116 females) were included in the analysis, and the range of onset-neuroimaging interval was 1 to 89 days (median [interquartile range] = 17 [7 to 30 days]). We divided the patients into quartiles based on their onset-neuroimaging interval (the first quartile: 0–6 days; the second quartile: 7–16 days; the third quartile: 17–29 days; the fourth quartile: ≥30 days). Among brain magnetic resonance imaging findings, the incidence of venous distension sign was high (>75%), with no difference among quartiles (p = 0.876). The incidence of diffuse pachymeningeal enhancement (p = 0.001), severe midbrain-pons deformity (p = 0.001), and subdural fluid collection (<0.001) followed a significant stepwise increase from the first quartile to fourth quartile. Patients with shorter onset-neuroimaging intervals were less likely to have neuroimaging scores ≥5 (<17 vs. ≥17 days: 72.9% vs. 86.4%; odds ratio = 2.3 [95% CI 1.1–5.1], p = 0.028), but not neuroimaging scores ≥3 (<17 vs. ≥17 days: 92.9% vs. 92.0%, p = 0.824). Conclusions: The emergence of brain magnetic resonance imaging findings of spontaneous intracranial hypotension depended on disease duration and appeared sequentially. When using brain magnetic resonance imaging findings or neuroimaging scores for diagnostic purposes, the onset–neuroimaging interval should be considered.