Reversible cerebral vasoconstriction syndrome as a cause of thunderclap headache: a retrospective case series study

Toll-like receptor-4 pathway as a possible molecular mechanism for brain injuries after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is known as an acute catastrophic neurological disease that continues to be a serious and significant health problem worldwide. The mechanisms contributing to brain injury after SAH remain unclear despite decades of study focusing on early brain injury (EBI) and delayed brain injury (DBI). Neuroinflammation is a well-recognized consequence of SAH and may be responsible for EBI, cerebral vasospasm, and DBI. Toll-like receptors (TLRs) play a crucial role in the inflammatory response by recognizing damage-associated molecular patterns derived from the SAH. TLR4 is the most studied Toll-like receptor and is widely expressed in the central nervous system (CNS). It can be activated by the extravasated blood components in myeloid differentiation primary response-88/Toll/interleukin-1 receptor-domain-containing adapter-inducing interferon-β (MyD88/TRIF)-dependent pathway after SAH. Transcription factors, such as nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK) and interferon regulatory factor (IRF), that regulate the expression of proinflammatory cytokine genes are initiated by the activation of TLR4, which cause the brain damage after SAH. TLR4 may therefore be a useful therapeutic target for overcoming EBI and DBI in post-SAH neuroinflammation, thereby improving SAH outcome. In the present review, we summarized recent findings from basic and clinical studies of SAH, with a primary focus on the biological characteristics and functions of TLR4 and discussed the mechanisms associated with TLR4 signaling pathway in EBI and DBI following SAH.

Reversible cerebral vasoconstriction syndrome at the emergency department

Objective

Reversible cerebral vasoconstriction syndrome (RCVS) is an underestimated cause of thunderclap headache that shares many characteristics with subarachnoid hemorrhage (SAH). This fact makes the two easily confused by emergency physicians. This study evaluated the clinical manifestations, radiological features, and outcomes of patients with RCVS.

Methods

The electronic medical records of 18 patients meeting the diagnostic criteria of RCVS at our emergency department between January 2013 and December 2014 were retrospectively reviewed.

Results

The mean patient age was 50.7 years, and 80% were women. Patients with RCVS encountered physicians 4.7 times before receiving an accurate diagnosis. The mean duration of symptoms until diagnosis was 9.3 days. All but one patient experienced severe headache of 8 to 10 on a numerical rating scale. A total of 44% of patients had nausea, and 66% of patients experienced worsening of the headache while gagging, leaning forward, defecating, urinating, or having sexual intercourse. The most frequently affected vessels were the middle cerebral arteries, which demonstrated a characteristic diffuse “string of beads” appearance. Four cases were complicated by SAH.

Conclusion

Patients with RCVS have a unique set of clinical and imaging features. Emergency physicians should have a high index of suspicion for this clinical entity to improve its rate of detection in patients with thunderclap headache when there is no evidence of aneurysmal SAH.