Use of invasive neuroradiological investigations in patients with normal computerised tomography.

A review of the results of neuroradiological investigation of patients in whom computed tomography had shown no intracranial abnormality showed that the use of invasive studies, particularly pneumoencephalography, has declined since installation of a computed tomography scanner, and indications for such studies have become firmer. Diagnostic yield from invasive procedures in patients presenting with epilepsy, dementia, headache (including facial pain), or loss of consciousness is negligible.