Background Primary angiitis of the central nervous system (PACNS) is a rare inflammatory disorder of the blood vessels of the central nervous system. It usually presents non-specifically with vague symptoms like headache, weakness, seizures and behavioural change. The cause is unknown. Our patient presented with what appeared to be post-concussion syndrome but was eventually diagnosed with PACNS.

Case report Our patient is a 70-year-old man who fell 10 ft from a ladder. He did not sustain any injuries and there were no immediate symptoms. He then developed nausea, dizziness and weakness associated with lethargy, headaches, somnolence and poor memory. He was managed as post concussion syndrome but subsequently developed urinary incontinence and unsteadiness.MRI head scan sequences showed extensive confluent high signal changes with diffusion weighted restriction lesions (figure 1). CT angiogram was normal. Lumbar puncture showed a raised protein level of 1098.7 mg/l. Brain biopsy showed a prominent leptomeningeal inflammatory infiltrate composed of lymphocytes, macrophages and multinucleated giant cells. Immunohistochemistry showed a mixed infiltrate of CD3, CD20 and CD68 positive cells consistent with PACNS (figure 2). He was treated with intravenous methylprednisolone and weekly pulse intravenous cyclophosphamide with complete recovery.

Conclusion PACNS is rare and the clinical presentation is non-specific. In our patient the presentation suggested post concussion syndrome.