Utility of lumbar puncture after a normal brain computed tomography scan in patients presenting to the emergency department with suspected subarachnoid haemorrhage: A new more rational approach?

OBJECTIVE: The diagnostic approach for patients presenting to EDs with headaches suspicious for subarachnoid haemorrhage (SAH) remains challenging. Modern third-generation computed tomography (CT) has been shown to be extremely sensitive in identifying SAH and may eliminate the need for lumbar puncture (LP) which is an invasive, time-consuming procedure with limited accuracy and complications. The aim of this study is to assess the utility of LP in patients being evaluated for possible SAH in the ED after a negative non-contrast CT scan of the brain, as well as addressing the knowledge gap in regard to rational diagnostics among clinicians. METHODS: We conducted a retrospective data analysis of patients being evaluated for possible SAH between June 2013 and June 2018 across three EDs in Victoria, Australia. A diagnosis of SAH was defined by SAH on CT or an abnormal cerebrospinal fluid result in conjunction with positive results on cerebral angiography. A follow-up period of 6 months was chosen. RESULTS: A total of 4407 patients met inclusion criteria; 397 (9%) patients were diagnosed with SAH on CT. A total of 388 patients underwent LP and 778 were admitted to hospital for further investigations and management. A total of 2613 patients discharged from ED without LP remained well at 6 months from their initial presentation, but 230 cases were lost to follow up. One patient died from haemorrhagic stroke during his third hospitalisation. A single patient demonstrated a true positive LP after a normal CT brain. CONCLUSION: LP is not required in all patients with suspected SAH who have a negative CT scan. There are defining patient characteristics that can be used to risk stratify patients and may eliminate the need for LP.