We sought to distinguish the subtypes of Primary angiitis of Central Nervous system (PACNS) and describe their outcomes in an Indian Cohort

PACNS is a rare disease with significant morbidity and mortality that has distinct subtypes with diagnostic complexity. 

This retrospective single center study included adult patients diagnosed with PACNS as per Calabrese and Malleck's criteria, between 2000-2019.  Small and medium vessel vasculitis were defined, and their clinical and radiological profile, treatment and outcomes were compared. Functional outcomes were noted at 6 months, 1 year and at last follow up, while relapses were noted at last follow up. A poor outcome was defined as modified Rankin scale >2

Of the 72 patients, 50(69.4%) were males. The small vessel vasculitis subtype  had a younger age at onset (30.5 vs 40.5 years, P=.014), presented less often as a stroke (22% vs 62%, P=.001) and had greater delay in diagnosis and treatment initiation (median of 620 days vs 118 days, P=.001) compared with medium vessel vasculitis subtype. Although no difference was noted at 6 months, small vessel vasculitis group had poor outcomes at 1 year and last follow up (57% vs 20%, P=.011 and 72% vs 34%, P= .005 respectively) and had more relapses at last follow up (89% vs 30%, P <.001) when compared to medium vessel vasculitis group. On analyzing the entire cohort, 50/72(69%) and 37/53 (69.8%) patients had a good outcome at 6 months and 1 year respectively. Relapse was noted in 35/72 (49%) at final follow up. The choice of the treatment regimen (steroids or steroids with cyclophosphamide) did not predict outcomes or relapses.

Small vessel vasculitis subtype of PACNS is a distinct entity that has diagnostic and treatment delays, poor long-term outcomes and more relapses. Recognizing the different subtypes of PACNS may help to expedite diagnosis and treatment.