Minimally Invasive Testing

Serology

R/o underlying processes. ANA, RF, anti-Ro/La, anti-Sm, anti-RNP, anti-dsDNA, APLS antibodies, ANCA, C3 & C4, cryoglobulins, SPEP/UPEP, quantitative IgG, ACE, infectious serol. (HIV, TP-EIA, Hep B/C at minimum).

LP

80%-90% abnormal. ↑ or nl OP, ↑ TP, ↑ WBC (lymph), ↑ IgG, ± OCB, micro neg Additionally send VZV IgG & IgM, CMV PCR (if pt is immunocompromised) & VDRL (if serum TP-EIA positive), & others as indicated

MRI

Most sensitive Dx test (>90% abnl). Multifocal, bilateral T2/DWI abnormalities ± enhancement involving G/W matter. Stroke >> ICH. Rare tumor-like mass lesion (about 4%).

Combination of neg MRI & LP has high neg predictive value

Invasive Testing

Conventional Angiography

Suspicion + consistent CSF or MRI → consider conventional angio.

Nonspecific pattern of beading, aneurysm, circumferential/eccentric irregularities, multiple occlusions.

Sensitivity 40%-90%, specificity 30% (CTA/MRA less sensitive compared to conventional angiography).

Path confirmed cases have shown normal angio (vascular abnormalities can occur in arteries smaller than resolution of angio).

Pathology

Gold standard. Clinical suspicion + prior w/u inconclusive or to confirm dx prior to Rx. Sample leptomeninges + cortex in an affected region if possible (vs. random sampling of non-dominate hemisphere if imaging negative). Segmental inflammation = false neg 25% vs. autopsy (J Neurol 2001;248:451). Targeted biopsies diagnostic 78% (Am J Surg Pathol 2009;33:35-43).

Histopathology: Granulomatous (most common, associated w/β-amyloid deposition), lymphocytic, or necrotizing pattern (least common, associated w/ICH).

Characteristics of PACNS vs. RCVS

RCVS

PACNS

Demographics

2:1 female

1:1

Acuity

Acute (usually severe thunderclap HA)

Subacute

Clinical setting

Defined setting (esp drug exposure, postpartum)

No clear setting

Reversibility

Days-weeks

Months or longer

CSF findings

Normal to near normal

Abnormal (leukocytosis + elevated TP)

MRI

Normal in 70% but can have evidence of localized SAH & less frequently ischemic or hemorrhagic stroke

Abnormal in >90% of patients

Angiography

Always abnormal, reversible in 6-12 wk

Possibly normal, diffuse abnormalities indistinguishable from RCVS

Treatment

Supportive +/- nimodipine

Steroids +/- cyclophosphamide