Primary angiitis of the central nervous system (PACNS) is inflammation of the blood vessels of the central nervous system (stating the obvious you might say). It differs from other forms of angiitis or vasculitis, such as lupus and giant cell arteritis (GCA), which respect no boundaries. PACNS is as dangerous a neurological disorder as they come, and just as rare. It requires aggressive, and paradoxically equally life-threatening, immunosuppressive treatment. Between the devil and deep blue sea-that’s exactly where the neurologist managing a patient with PACNS will be found.

The clinical features of PACNS are unfortunately very non-specific and include headaches, seizures, stroke, and cognitive changes. This makes PACNS is a challenge to diagnose. Even when suspected, PACNS may evade detection even by the special scan of the blood vessels called angiography. More frequently, the only certain way of confirming this disease in life is with a brain biopsy. Did I say ‘certain’? I take that back. Alas, even brain biopsy is not guaranteed to make the diagnosis of PACNS. A high degree of confidence and teeth-gritting is therefore an absolute requirement in any neurologist unfortunate enough to come face-to-face with this menace.

To make complicated matters even worse for the unwary neurologist, there are now reports suggesting that PACNS presents in even rarer and atypical ways. For the neurological Sherlocks and Poirots, here are 2 unusual presentations of PACNS.

Isolated spinal cord involvement

This is a case report from the Journal of Neurology of a 44-year old woman who presented with PACNS but with purely spinal cord involvement and completely sparing the brain. The diagnosis in this case was only confirmed with a spinal cord biopsy. The authors reviewed the literature and only found 8 previous reports of PACNS beginning in the spinal cord, and half of these progressed to involve the brain. 

Unilateral cerebral presentation

Most cases of PACNS evenly involve both sides of the brain. This report, again from Journal of Neurology, bucks this trend with the report of a 55-year old man who had PACNS which only involved the left side of his brain. This unilateral hemispheric PACNS is a reminder that an entity called focal PACNS exists.

Do you have any sightings of unusual cases of PACNS? Please drop a comment

_________________________________________________________________________