Radiologically defined acute hydrocephalus in aneurysmal subarachnoid haemorrhage

Acute hydrocephalus is a known complication in aneurysmal subarachnoid haemorrhage. Current clinical decisions about cerebrospinal fluid diversion rely on subjective assessments. Radiological tools to guide these decisions are limited. Ventriculomegaly is frequently observed in patients with aSAH. However, no standardized imaging measure has been widely accepted. The bicaudate index has been proposed as a potential indicator. Prior research has shown its use in some neurological conditions. No prior work had resolved its applicability in aSAH. This gap motivated the development of a threshold BCI to guide CSF diversion.

The aim was to determine a threshold bicaudate index that may predict the need for cerebrospinal fluid diversion in aSAH patients. Clinical deterioration is a key factor in decision-making. The study focused on patients who worsened after initial presentation. A derivation group was used to calculate BCI thresholds. The test group evaluated the thresholds in a different cohort. Age was considered as a modifying factor. The researchers proposed that thresholds could improve objectivity in clinical decisions. This approach may reduce unnecessary interventions.

The study used a prospective registry to collect data from aSAH patients. The derivation group included patients with World Federation of Neurosurgical Societies grades 1-2 who deteriorated. Post-deterioration CT scans were analyzed for BCI measurements. The lower limit of the 95% confidence interval was used as the hydrocephalus threshold. Age groups were stratified into three categories. The test group included patients with WFNS grades ≥2. Diagnostic CT scans were compared with CSF diversion within 24 hours. The researchers proposed that this method could standardize clinical assessments.

In the derivation group, 62 patients underwent CSF diversion. The mean post-deterioration BCI was 0.19 for patients aged ≤49 years. For those aged 50-64 years, the mean BCI was 0.22. Patients aged ≥65 years had a mean BCI of 0.24. The corresponding hydrocephalus thresholds were 0.17, 0.20, and 0.22, respectively. In the test group, 105 patients were evaluated. No significant difference in BCI was found between good and poor grade patients aged ≤49 and ≥65 years. Only 50% of patients who underwent CSF diversion exceeded the BCI thresholds. These findings suggest a lack of objective evidence in some cases.

The study proposed that a significant proportion of aSAH patients may receive CSF diversion without clear radiological evidence of hydrocephalus. The derived BCI thresholds may provide an objective measure for clinical decision-making. However, the authors suggested that further testing is required to validate these thresholds. The findings may influence how clinicians interpret imaging in aSAH. Age-based thresholds were proposed to improve accuracy. The researchers did not claim that all patients with BCI below the threshold can avoid CSF diversion. The study did not propose that BCI is the only factor in decision-making. The authors suggested that thresholds could reduce variability in clinical practice.