Impact of Symptom Duration on Brain Imaging Findings in Spontaneous Intracranial Hypotension

Spontaneous intracranial hypotension (SIH) is characterized by distinctive brain imaging findings. The Bern SIH score integrates key imaging features to aid diagnosis and standardize radiological work-up. This cross-sectional study assessed the association between symptom duration at baseline MRI and the corresponding Bern SIH score.

All consecutive SIH patients evaluated at our department between January 2013 and January 2025 were retrospectively screened. The relationship between symptom duration at baseline MRI and Bern SIH score severity was explored by categorizing data into quartiles. Ordinal logistic regression with restricted cubic splines modeled the nonlinear association between symptom duration and the Bern SIH score. Common odds ratios were estimated relative to symptom onset and plotted over the first 52 weeks.

In total, 220 SIH patients (mean±SD age 51±14 years; 65% female) were included. The median symptom duration at baseline MRI was 5 weeks [interquartile range (IQR) 2-19] with a median Bern SIH score of 7 (IQR 4-9). Baseline Bern SIH score increased from the first quartile (median symptom duration 1.0 week; median Bern SIH score 6) to the second (4.0 weeks, SIH 8) and third quartile (8.8 weeks, SIH 7), followed by a decrease in the fourth quartile (52.3 weeks, SIH 4). Imaging features followed a similar pattern, with higher prevalence of dural enhancement, venous distention, and subdural hygromas in the second and third quartiles and lower prevalence in the fourth quartile. The severity of SIH score demonstrated a nonlinear pattern over symptom duration, with an early increase followed by gradual improvement. While adjustment for clinical factors attenuated the association and statistical significance was lost, the observed temporal trajectory remained consistent and clinically meaningful.

We observed a nonlinear trajectory of the Bern SIH score, with higher baseline scores in patients presenting in the first weeks after symptom onset and lower scores over subsequent months or years. These results underscore the dynamic nature of SIH and highlight the importance of interpreting diagnostic tests within the temporal context of symptom duration and disease evolution. A low Bern SIH score in patients with long symptom duration should not exclude SIH.