Thunderclap Headache and THC Triggers Characterize RCVS in Comparative Stroke Study

In a three-year retrospective investigation conducted at a single comprehensive stroke center, researchers analyzed and compared inpatient cases of two rare neurovascular disorders, reversible cerebral vasoconstriction syndrome (RCVS) and posterior reversible encephalopathy syndrome (PRES), identifying distinct diagnostic timelines, symptom profiles, and suspected triggers between the conditions. The clinical review evaluated 30 inpatient admissions, comprising 21 PRES cases and 9 RCVS cases, to better characterize demographics, medical histories, presentations, diagnostic evaluations, lengths of stay, complications, and treatments.

Prior medical histories differed substantially between the two patient cohorts. Among patients diagnosed with RCVS, migraine represented the predominant comorbidity, documented in 56 percent of cases (n = 5 of 9), followed by chronic pain, which was present in 44 percent of cases (n = 4 of 9). Conversely, patients presenting with PRES exhibited a medical background predominantly characterized by chronic cardiovascular and renal conditions, with hypertension identified in 81 percent of individuals (n = 17 of 21) and chronic kidney disease noted in 38 percent of cases (n = 8 of 21).

The initial clinical presentations also followed markedly divergent trajectories. Every patient diagnosed with RCVS presented with headache (n = 9 of 9, 100 percent), with thunderclap headache observed in 89 percent of cases (n = 8 of 9), alongside other headache manifestations such as headache different from usual migraine, positional headache, and new migraine. In contrast, individuals diagnosed with PRES most commonly presented with altered mental status (n = 15 of 21, 71 percent) and focal neurologic deficits (n = 10 of 21, 48 percent). Initial neurologic physical examination findings reinforced this disparity, showing altered mental status in 86 percent of PRES patients (n = 18 of 21).

Diagnostic investigations highlighted differing diagnostic pathways and imaging strategies for each syndrome. A CT angiogram served as the primary imaging modality for all RCVS cases (n = 9 of 9, 100 percent), whereas magnetic resonance imaging functioned as the primary imaging approach in 86 percent of PRES cases (n = 18 of 21). Urine drug screening was completed for 67 percent of the RCVS cohort (n = 6 of 9) and 52 percent of the PRES cohort (n = 11 of 21). Among the individuals with RCVS who underwent toxicology testing, 67 percent (n = 4 of 6) returned positive results for THC.

Evaluating suspected triggers identified by clinicians further distinguished the two neurovascular syndromes. The most frequent physician-identified trigger among RCVS patients was THC, implicated in 78 percent of cases (n = 7 of 9). For individuals with PRES, hypertension represented the primary physician-identified trigger, documented in 71 percent of patients (n = 15 of 21). These suspected triggers aligned closely with the predominant baseline comorbidities and toxicological findings observed across both patient groups.

The clinical trajectories in the inpatient setting revealed sharp differences in time to diagnosis, hospitalization duration, and inpatient morbidity. Patients diagnosed with PRES experienced a shorter median time to diagnosis of 1 day (interquartile range 1 to 2 days) compared to a median of 3 days (interquartile range 2 to 4 days) for those with RCVS. However, PRES patients required a longer median length of hospital stay at 5 days (interquartile range 3 to 9 days), compared to a median length of stay of 1 day (interquartile range 1 to 2 days) for RCVS patients. Furthermore, clinical complications occurred exclusively within the PRES group, with seizures developing in 48 percent of patients (n = 10 of 21) and respiratory failure occurring in 19 percent (n = 4 of 21), whereas no complications were recorded among patients in the RCVS cohort.

Therapeutic management reflected the differing underlying presentations and risks associated with each condition. The majority of patients with RCVS received treatment with verapamil, administered in 89 percent of cases (n = 8 of 9). Management of PRES focused primarily on blood pressure control, which was administered to 95 percent of patients (n = 20 of 21), alongside antiseizure medications prescribed in 33 percent of cases (n = 7 of 21). The authors concluded that RCVS cases were enriched in individuals with migraine presenting with thunderclap headache and linked to THC as the primary identified trigger, whereas PRES cases were characterized by altered mental status, hypertension triggers, faster diagnostic confirmation, longer hospital stays, and more frequent medical complications.

Because both conditions represent rare neurovascular disorders, the comparative study was designed to clarify distinguishing clinical features that can assist inpatient evaluations. By systematically reviewing medical records across three years, the researchers examined how specific baseline factors, acute presentations, and diagnostic choices differed across admissions. The findings demonstrate that distinguishing reversible cerebral vasoconstriction syndrome from posterior reversible encephalopathy syndrome depends on recognizing key clinical divergences, notably the presence of severe thunderclap headache versus acute changes in mental status.

These clinical differences directly corresponded to the diagnostic testing and inpatient resources documented for each disorder. In reversible cerebral vasoconstriction syndrome, the high frequency of thunderclap headache was accompanied by universal vascular imaging with CT angiography, alongside toxicological screening that frequently detected THC. By comparison, patients with posterior reversible encephalopathy syndrome primarily underwent magnetic resonance imaging and experienced longer inpatient hospitalizations accompanied by acute complications, including seizures and respiratory failure. Together, the observed differences illustrate distinct clinical profiles and hospital care pathways for these two neurovascular syndromes.

Subject of Research: Clinical characteristics, diagnostic timelines, triggers, and management of RCVS and PRES

Article Title: Three years of RCVS and PRES cases at a single comprehensive stroke center: observations on clinical presentation, headache features, triggers, and management

Article References: Ahmad, S. R., Challa, S. A., Suh, L., & Kaur, S. (2026). Three years of RCVS and PRES cases at a single comprehensive stroke center: observations on clinical presentation, headache features, triggers, and management. Frontiers in Neurology, 17, Article 1870218. https://doi.org/10.3389/fneur.2026.1870218

Image Credits: AI Generated

DOI: 10.3389/fneur.2026.1870218

Keywords: reversible cerebral vasoconstriction syndrome, posterior reversible encephalopathy syndrome, RCVS, PRES, thunderclap headache, migraine, chronic pain, hypertension, chronic kidney disease, altered mental status, focal neurologic deficits, urine drug screening, THC, CT angiogram, magnetic resonance imaging, verapamil, antiseizure medication, stroke center