General description

Primary angiitis of the central nervous system (PACNS) is a rare, idiopathic vasculitis that affects small to medium-sized arteries confined to the brain and spinal cord, with no systemic involvement. It most commonly occurs in men around the age of 50. The condition presents with diverse and nonspecific symptoms due to diffuse and scattered lesions, ranging from acute to chronic in progression.

Common clinical features

PACNS presents with nonspecific and variable symptoms, typically reflecting multifocal involvement of the brain and spinal cord.

• Headache: The most frequent symptom, often persistent and progressive, with a subacute to chronic course. Unlike [[Reversible cerebral vasoconstriction syndrome (RCVS)], thunderclap headaches are uncommon.
• Cognitive impairment: Gradual cognitive decline and altered mental status are common initial symptoms.
• Stroke and transient ischemic attacks (TIA): Present in up to 30–50% of cases, often involving multiple vascular territories.
• Other Neurological Manifestations: Cranial nerve palsies, seizures, ataxia, and in rare cases, spinal cord symptoms or meningitis-like presentations.

Symptoms outside the central nervous system, such as systemic inflammation, weight loss, or organ involvement, are rare in PACNS and suggest alternative diagnoses, emphasizing the importance of excluding systemic vasculitis and secondary causes.

Diagnostic considerations

• Imaging: MRI is abnormal in over 90% of cases, showing nonspecific findings. Cerebral angiography may reveal "beading" suggestive of vasculitis, although similar findings are seen in RCVS, which resolves within three months and typically lacks cerebrospinal fluid (CSF) abnormalities.
• CSF analysis: Often reveals mild, nonspecific abnormalities, such as elevated protein levels or white blood cell counts.
• Definitive diagnosis: Requires brain biopsy or angiographic evidence of vasculitis and exclusion of secondary causes such as infections (e.g., Varicella zoster virus) or malignancies, particularly lymphoproliferative disorders.