From the Guidelines
Lumbar puncture is a crucial diagnostic tool for CNS vasculitis, as it provides valuable cerebrospinal fluid (CSF) analysis that can help confirm the diagnosis, with typical findings including mild to moderate pleocytosis, elevated protein levels, and normal or slightly decreased glucose 1. When performing a lumbar puncture for suspected CNS vasculitis, clinicians should collect CSF for cell count, protein, glucose, cultures, cytology, and specialized tests like oligoclonal bands and IgG index.
- The procedure should be performed with standard technique using a 20-22G spinal needle, collecting 4-6 tubes of CSF (approximately 2-3 mL each).
- Prior to the procedure, coagulation studies should be checked, and anticoagulants or antiplatelets should be appropriately managed.
- While CSF findings are often abnormal in CNS vasculitis, they are nonspecific, so results must be interpreted alongside clinical presentation, neuroimaging (particularly MRI with contrast), and sometimes brain biopsy.
- The lumbar puncture helps exclude infectious causes that can mimic vasculitis and provides supportive evidence for the inflammatory nature of the disease process, guiding treatment decisions that typically involve immunosuppressive therapy, such as corticosteroids and cytotoxic agents 1.
- It is essential to note that distinguishing between transient or nonprogressive and progressive arteriopathies at presentation is not straightforward, and treatment should be individualized based on the patient's specific condition and response to therapy 1.
From the Research
CNS Vasculitis and Lumbar Puncture
- Lumbar puncture (LP) is a diagnostic tool used in the evaluation of central nervous system (CNS) vasculitis, with a sensitivity of 53% for detecting CNS vasculitis 2.
- The combination of LP and either computed tomography (CT) or magnetic resonance imaging (MRI) is more sensitive than LP alone, with sensitivities of 92% and 100%, respectively 2.
- CSF analysis can detect alterations in patients with CNS vasculitis, with 3 out of 5 patients who underwent lumbar puncture showing alterations in one study 3.
- The use of LP, CT, and MRI can be beneficial in the diagnosis of CNS vasculitis, but the sensitivities of these tests are only modest, and a normal LP and normal CT or MRI do not rule out the possibility of CNS vasculitis 2.
Diagnostic Challenges
- The diagnosis of primary CNS vasculitis is often difficult due to the lack of specific clinical features, classical clinical course, and confirmatory blood or imaging investigations 4.
- Contrast catheter cerebral angiography is neither specific nor sensitive, but it is still used to underpin the diagnosis in many published studies 4.
- A binary set of diagnostic criteria has been proposed, dividing cases into "definite" primary CNS vasculitis, where tissue proof is available, and "possible," where it is not 4.
Treatment and Management
- Therapy for CNS vasculitis remains largely empiric, guided by observational data, with glucocorticoids and cyclophosphamide being the mainstays of therapy in primary angiitis of the CNS (PACNS) 5.
- Securing a diagnosis through a careful, team-based approach with emphasis on ruling out possible mimics is paramount in the management of patients with CNS vasculitis 5.
- Treatment response and outcomes can be unfavorable, with fatal outcomes in some cases, highlighting the importance of prompt and accurate diagnosis 3.