What is Subarachnoid Hemorrhage (SAH)? Latest Knowledge: "Worst Headache of Life," Treatment (Coiling/Clipping), and Prognosis

Subarachnoid Hemorrhage (SAH) is one of the most fatal types of stroke, demanding immediate action as time is critical for patient survival. The annual incidence in Japan is approximately 30,000 cases, with over 80% of cases caused by the sudden rupture of a cerebral aneurysm. The most characteristic signs of this disease are the “worst headache of life, like being hit by a hammer,” vomiting, and temporary loss of consciousness.

Overview of Subarachnoid Hemorrhage (SAH): 2025 Latest Summary

Item	Content
Definition	Sudden bleeding into the space beneath the arachnoid membrane that covers the brain (the subarachnoid space). It is strictly separate from “intracerebral hemorrhage” as the bleeding is not within the brain tissue itself.
Annual Incidence in Japan	Approx. 30,000 cases (25 per 100,000 people). Most common in women aged 40–60s.
Mortality Rate	Approx. 30–40% within 30 days of onset (caused by re-bleeding or vasospasm). Of survivors, approx. 30% are left with severe residual deficits.
Most Common Cause	Rupture of a Cerebral Aneurysm (approx. 80–85%). Others include vascular malformations or unknown causes (approx. 10%).

Main Symptoms (Extremely Acute!)

Symptom	Characteristic
Severe Headache	“Worst headache of life” or “like being hit by a hammer,” present in over 90% of cases.
Vomiting	Projectile vomiting (like a fountain).
Loss of Consciousness	Occurs for seconds to minutes during the attack in over 50% of cases.
Neck Pain/Stiffness	Appears 2–12 hours after onset.
Seizures/Limb Paralysis	Occurs in 10–20%.

→ If these occur, call 911 immediately! The sooner the patient receives care, the higher the chances of survival.

Dangerous Timeline Post-Onset (Life-Threatening Risks)

Time	Maximum Risk
Onset ∼ 24 Hours	Re-bleeding (The initial ruptured aneurysm bleeds again) → Mortality rate over 50%.
Days 4 ∼ 14 Post-Onset	Cerebral Vasospasm (Blood vessels tightly contract) → Leads to cerebral infarction (ischemic stroke).
2 Weeks ∼ 1 Month Post-Onset	Hydrocephalus (Accumulation of cerebrospinal fluid).

Standard Treatment Flow (Current as of 2025)

Onset → Ambulance → Head CT Scan (Diagnoses SAH in 99% of cases).
Cerebral Angiography (3D-CTA or DSA) to confirm the aneurysm’s location and size.
Treatment must be performed within 72 hours of onset (to prevent re-bleeding).

Treatment Method	Characteristics / Indication	2025 Ratio in Japan
Coiling (Endovascular Embolization)	Catheters are used to fill the aneurysm with coils (minimally invasive).	Approx. 75–80%
Clipping (Open Surgery)	The skull is opened, and a clip is placed at the base of the aneurysm (highly definitive).	Approx. 20–25%

→ The decision to perform either coiling or clipping within the first 3 days of onset is the single most important factor determining survival rate and prognosis!

Sequelae in Survivors (1 Year Post-Onset)

Condition	Percentage
Return to near-normal life	50–60%
Mild disability (slight unsteadiness, etc.)	20%
Moderate to Severe disability (requires care)	15–20%
Vegetative state	Approx. 5%

Most Important Prevention

Risk	Prevention Method
Unruptured Aneurysm	Get a Brain Checkup (MRA) at least once for ages 40+.
Hypertension	Maintain blood pressure below 130/80 mmHg.
Smoking	Complete cessation (smokers have 5–10 times the risk of non-smokers!).
Excessive Alcohol	Limit to 12g/day for women, 25g/day for men.

Summary

If you experience “Headache like being hit by a bat + Vomiting + Loss of Consciousness,”

Call 911 immediately → Treatment with coiling or clipping within 3 days of onset dramatically increases the chances of survival!