Pseudo subarachnoid hemorrhage sign – Pitfall of rapid therapy implementation in bacterial meningitis

Abstract-Text (inkl. Referenzen und Bildunterschriften)

An 81-year-old female was initially brought to the emergency department with a suspected stroke. She had been suffering from fever and diarrhea for several days, evolving headache and confusion preceded the acute onset. On clinical examination we observed an afebrile encephalopathic patient with a forced gaze towards the left side. The initial multimodal cranial CT scan was normal, laboratory results revealed a marked thrombocytopenia, elevation of C-reactive protein, lactatemia, plasmatic coagulation disorder and acute renal failure. The encephalography showed a right-sided focal status epilepticus, terminated by application of benzodiazepines. The subsequent coma required emergency intubation and mechanical ventilation. With rapid development of marked bilateral light-unresponsive dilated pupils, a CT scan (Figure 1) was repeated with evidence of diffuse hyperdensities in the supra- and infratentorial subarachnoid spaces, suspicious of subarachnoid hemorrhage (SAH). In absence of active bleeding and any aneurysm, this was radiologically classified as a pseudo SAH sign [1], which is, inter alia, indicative for severe bacterial meningitis. Cerebrospinal fluid (CSF) analysis showed pronounced pleocytosis, high protein and elevated lactate confirming the diagnosis of bacterial meningitis. Despite of intensified sepsis-specific therapy with administration of antibiotics, escalated volume and vasopressor administration, and dialysis, the patient died two days later in refractory septic shock with multiple organ failure and disseminated intravascular coagulation. Microbiological cultures revealed Escherichia coli in CSF, urine, and blood, indicating a urinary tract infection as primary focus.

The radiographic mimic of pseudo SAH can be associated with meningitis as well as non-infectious etiologies indicative of increased permeability of the blood-brain barrier. In our case the sign was most likely related to contrast administration during initial CT, accumulation due to renal failure and disruption of blood-brain barrier in meningoencephalitis. We critically emphasize that this rare radiological finding should be recognized in sepsis with/or meningoencephalitis and must not distract from advanced focus diagnostics as well as rapid administration of antibiotics.

[1] Fretwell, M. et al. Pseudo Subarachnoid Hemorrhage Sign in Bacterial Meningitis in a Patient Presenting With Acute Ischemic Stroke: A Novel Radiological Clue to Rapid Diagnosis. Cureus 14 (2022).