Subarachnoid Intra-cranial Lipiodol Deposits

Lipiodol, an oil-based contrast medium first introduced in 1944, was commonly used for various radiological exams until the 1980s, when it was replaced by water-soluble contrast media due to complications such as arachnoiditis and chronic irritations. Due to its slow resorption rate, asymptomatic lipiodol deposits can occasionally be found incidentally. This case report describes a 93-year-old man who presented to the emergency department after a fall. A non-contrast head CT scan, performed to rule out subarachnoid hemorrhage, revealed numerous hyperdense droplets in the subarachnoid spaces of the brain, primarily around the temporal lobes. Further investigation uncovered a previous pelvic X-ray showing similar hyperdense droplets around the cauda equina. The patient's history indicated a lipiodol myelography performed 51 years earlier. Lipiodol deposits are generally found in the lumbar region, making an intra-cranial location particularly rare. When present, these deposits are visible as radiopaque droplets on X-rays, hyperdense droplets on CT scans, and hyper-T1 on MRI, though the T2 signal is variable. Though lipiodol deposits are generally left untreated, symptomatic spinal deposits may be surgically removed. This rare case underscores the importance of thorough patient history in diagnosing subarachnoid lipiodol deposits, a condition relevant only in older patients who underwent myelography before the 1980s.