Intracranial and systemic manifestations of familial leptomeningeal amyloidosis, as seen on CT and MRI.

Leptomeningeal amyloidosis is a subset of familial transthyretin amyloidosis, a family of diseases occurring in conjunction with multiple known mutations of the transthyretin gene. Though this is primarily a disease of the central nervous system, amyloid deposition is multisystemic. We describe a case of a 61-year-old man with known central nervous system amyloidosis presenting to the emergency room with stroke-like symptoms, including left hemineglect, right gaze paresis, and left hemiplegia, atop baseline dementia. A noncontrast CT head demonstrated ventriculomegaly and no acute hemorrhage. Urinalysis indicated an underlying urinary tract infection, ultimately believed to have prompted a breakthrough seizure. Electroencephalogram revealed diffuse encephalopathy. Contrast-enhanced MRI demonstrated hallmarks of intracranial amyloid with no new infarct. Previously taken noncontrast CT neck and thorax demonstrated evidence of systemic disease.