Spontaneous intracranial hypotension (SIH) is an unusual syndrome that is characterised by positional headache, neck rigidity, nausea and vomiting. The characteristic magnetic resonance imaging (MRI) findings are diffuse smooth pachymeningeal thickening and enhancement, downward displacement of posterior fossa structures and pituitary gland enlargement. An unusual case of SIH with pituitary macro-adenoma and subsequent subdural haemorrhage is presented, and its clinical picture, MRI findings and possible pathophysiological mechanism are discussed.