Differential Diagnosis for Primary CNS Angiitis

When considering primary CNS angiitis, it's crucial to approach the diagnosis systematically, taking into account the clinical presentation, imaging findings, and laboratory results. Here's a structured differential diagnosis:

• Single Most Likely Diagnosis
  • Multiple Sclerosis (MS): Often presents with relapsing-remitting neurological deficits, which can mimic the symptoms of primary CNS angiitis, such as vision loss, weakness, and cognitive impairment. MS is more common and should be considered first due to its prevalence.
• Other Likely Diagnoses
  • Systemic Lupus Erythematosus (SLE): Can cause CNS vasculitis, presenting similarly to primary CNS angiitis with headaches, seizures, and psychiatric symptoms. The presence of other systemic symptoms or autoantibodies can guide this diagnosis.
  • Giant Cell Arteritis: Although it typically affects larger vessels outside the CNS, it can occasionally present with similar symptoms, especially in older adults, and should be considered due to its potential for serious complications if untreated.
• Do Not Miss Diagnoses
  • Infectious Vasculitis (e.g., Varicella-Zoster Virus): Can cause CNS vasculitis, particularly in immunocompromised patients. Missing this diagnosis could lead to severe consequences, including stroke and death, if not promptly treated with antiviral therapy.
  • Reversible Cerebral Vasoconstriction Syndrome (RCVS): Presents with thunderclap headaches and can be associated with vasculitis or drug use. It's critical to distinguish RCVS from primary CNS angiitis due to differences in treatment and prognosis.
• Rare Diagnoses
  • Polyarteritis Nodosa (PAN): A systemic vasculitis that rarely affects the CNS but can cause similar symptoms. Its inclusion in the differential is important due to its distinct treatment approach.
  • Granulomatosis with Polyangiitis (GPA): Formerly known as Wegener's granulomatosis, GPA can involve the CNS and cause symptoms overlapping with primary CNS angiitis, although it more commonly affects the respiratory tract and kidneys.

Each of these diagnoses requires careful consideration based on the patient's clinical presentation, laboratory findings, and imaging studies to ensure accurate diagnosis and appropriate management. Primary CNS angiitis itself is a rare condition characterized by inflammation of the blood vessels within the CNS, leading to symptoms such as stroke, headache, and cognitive decline, and its diagnosis often involves ruling out these other conditions.