Locations:
Search IconSearch
April 4, 2018/Neurosciences

PACNS or RCVS? Differences in Clinical Presentation

How to tell the difference and why it matters

16-RHE-871-Calabrese-Hero-Image-650x450pxl

By Rula Hajj-Ali, MD, and Leonard Calabrese, DO

Advertisement

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Primary angiitis of the central nervous system (PACNS) is a devastating disease in which exclusive inflammation and destruction of vessels in the CNS cause progressive, debilitating neurological deficits. Prognosis improves greatly with proper treatment, but with nonspecific tests and many confounding mimics, diagnosis can be tricky.

One of PACNS’s closest mimics is reversible cerebral vasoconstriction syndrome (RCVS). The distinguishing characteristic of this group is the “thunderclap” headache — sudden, severe and with or without neurological deficits. Originally, rheumatologists treated RCVS as benign angiopathy of the CNS. In 2007, Calabrese et al set forth RCVS as a concept encompassing several syndromes with unifying clinical, laboratory and radiologic features. The clinical features and diagnostic criteria described in that paper have been considered the standard since its publication.

Distinguishing between RCVS and PACNS is critical because the treatment protocol is so vastly different. Misdiagnosing PACNS as RCVS can deprive a patient of medications that prolong survival and improve outcomes. These conditions are close mimics, but the astute clinician has several tools in her armamentarium to distinguish between them. We offer a brief overview of differences in clinical presentation below. Future posts will discuss differences in test results and management.

Clinical presentation

Patients with PACNS are more commonly male and trend older with a mean age of 50 years at onset, while patients with RCVS are more likely to be female and a bit younger. Patients with both conditions almost always present with headaches, but the differences in onset and type are important to distinguish between the mimics. Patients with PACNS experience subacute onset of headaches with focal and nonfocal deficits; a patient with sudden-onset, severe, “thunderclap” headaches should be considered for RCVS whether or not neurological deficits are present. RCVS is monophasic, but patients with PACNS will experience these symptoms chronically.

Advertisement

When patients present with these symptoms, diagnostic tests can help eliminate the mimics and narrow towards a precise diagnosis.

Dr. Hajj-Ali is Associate Director of the Center for Vasculitis Care and Research in the Department of Rheumatic and Immunologic Diseases. Dr. Calabrese is Director of the R.J. Fasenmyer Center for Clinical Immunology.

Advertisement

Related Articles

Man demonstrating augmented reality tool for gait freezing
July 23, 2025/Neurosciences/Research
Augmented Reality Cueing Reduces Parkinson’s Related Gait Freezing

Various AR approaches affect symptom frequency and duration differently

x-rays of hardware between spine segments
Diabetes and Obesity Are Red Flags for Spinal Fusion Complications

Meta-analyses signal an opportunity to reshape risk stratification and surgical protocols for these comorbidities

Dr. James Liao against a decorative backdrop with podcast overlay
July 16, 2025/Neurosciences/Podcast
Demystifying Diagnosis of Gait Impairment: NPH and Beyond (Podcast)

Technology helps address gait abnormality in normal pressure hydrocephalus and more

Illustration of a brain and genetic strands
Normal Pressure Hydrocephalus: A Complex Interplay of Genetic and Environmental Factors

Large analysis of familial cases and genomic studies sheds light on genetic contributions

portraits of dr. mark bain and dr. francois bethoux against decorative background
July 2, 2025/Neurosciences/Podcast
Next Frontier in Stroke Recovery (Podcast)

Increasing treatment options are extending the window for continued functional gains

teenage girl in a wooded outdoor setting
Accelerated Aging May Be Present in the Youngest Patients With Multiple Sclerosis

Case-control study yields evidence of epigenetic aging in pediatric-onset MS

Ad