Spontaneous subdural haematoma secondary to undiagnosed metastatic gastric adenocarcinoma

A man in his 80s presented with 3 weeks of lower back pain, generalised weakness, poor appetite and intermittent melena, without genitourinary symptoms or recent trauma. CT showed an old L1 compression fracture and new sclerotic lesions in the L3 and L4 vertebrae, as well as mildly enlarged abdominal lymph nodes. 3 days later, he returned to the emergency department with worsening symptoms, including new left hemiparesis. A head CT revealed a right subdural haematoma (SDH) with a midline shift. Despite treatment for disseminated intravascular coagulation, the patient's condition deteriorated, leading to a suspicion of spontaneous intracranial hypotension. An autopsy revealed disseminated metastatic adenocarcinoma with dura and leptomeningeal metastases, ultimately causing spontaneous SDH and subsequent transtentorial herniation. This case highlights the impact of anchoring bias in clinical decision-making and the importance of early recognition of underlying malignancy as the aetiology of spontaneous SDH in patients presenting with signs and symptoms of metastatic cancer.