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Thunderclap Headache ✅

⚡ Thunderclap headache (TCH) is a sudden, severe headache that reaches maximal intensity within seconds to minutes. ❗ Always consider subarachnoid haemorrhage (SAH) until proven otherwise. Rapid recognition and early management save lives.

📖 Definition

Severe headache reaching maximum intensity within 1 minute.
Often described as "worst headache of life" by patients.
May be associated with nausea, vomiting, photophobia, neck stiffness, or collapse.

🧠 Pathophysiology

Sudden arterial rupture (aneurysm) → bleeding into subarachnoid space → meningeal irritation, raised ICP.
Other causes: sudden vascular events (dissection, RCVS), venous congestion (sinus thrombosis), pituitary apoplexy, hypertensive crises.

⚡ Red Flags

Onset to maximal intensity <1 minute.
Neurological deficit (focal signs, seizures, altered consciousness).
Signs of raised ICP (vomiting, papilloedema).
History of trauma, anticoagulation, illicit drug use (cocaine, amphetamines).
Previous SAH or known aneurysm.

🚑 Initial Assessment & Immediate Actions

ABCDE: Ensure airway, breathing, circulation; oxygen if hypoxic; monitor vitals and GCS.
Insert IV access and monitor fluid balance.
Assess for neurological deficits, meningism, seizure activity.
Check medications (anticoagulants, antiplatelets) and coagulation status.
Urgent senior/neurology/neurosurgery review.

🔍 Investigations

Non-contrast CT head: First-line; ~95% sensitive within 6 hours for SAH.
CT angiography (CTA): Localises aneurysm; plan for endovascular repair.
Lumbar puncture: If CT negative and suspicion remains; look for xanthochromia ≥6 hours post-onset.
MRI/MRA: Consider for RCVS, venous sinus thrombosis, pituitary apoplexy.
Blood tests: FBC, U&E, coagulation, troponin if ACS suspected.
Other: ECG, vital signs, blood pressure monitoring.

📊 Differential Diagnosis

⚡ Thunderclap Headache – Causes, Investigation, and Management

🧠 Thunderclap headache is a severe headache that reaches maximum intensity within 1 minute. It is a medical emergency until serious causes are ruled out, particularly subarachnoid haemorrhage (SAH). Early recognition, prompt imaging, and specialist referral are crucial.

📊 Thunderclap Headache – Causes, Features & Investigations

Cause	Typical Features / Clinical Clues	Investigations / Notes
🩸 Subarachnoid Haemorrhage (Aneurysmal SAH)	💥 Sudden “worst headache of life”, peaks <1 min; ± nausea, vomiting 🤮, meningism 🧠, collapse, photophobia; often age 40–60	🖼 Non-contrast CT head (<6h sensitivity ~95%); CTA for aneurysm location; LP if CT negative; urgent neurosurgical input
🧿 Perimesencephalic SAH	⚡ Mild thunderclap headache; usually no deficits; benign course; no collapse	🖼 CT head: blood around midbrain; CTA often normal; conservative management; excellent prognosis ✅
🌪 Reversible Cerebral Vasoconstriction Syndrome (RCVS)	🔁 Recurrent thunderclap headaches over days–weeks; triggered by exertion, sexual activity, postpartum, drugs (SSRIs, triptans, stimulants)	🖼 CTA/MRA: segmental arterial narrowing; CT may be normal initially; monitor for stroke or cortical SAH
🧬 Cervical / Intracranial Artery Dissection	🦴 Neck pain, unilateral headache, Horner’s syndrome (ptosis, miosis), stroke/TIA symptoms	🖼 CTA/MRA neck ± brain; MRI shows mural hematoma; antithrombotic therapy guided by stroke team
🩹 Intracerebral Haemorrhage (ICH)	💥 Sudden severe headache with focal deficits; hypertension common; possible nausea, vomiting, reduced GCS	🖼 CT head diagnostic; CTA if vascular malformation suspected; BP control and neurosurgical referral
🧪 Cerebral Venous Thrombosis (CVT)	⚡ Thunderclap or subacute headache; seizures, papilloedema 👁; often young females, pregnancy, OCP use; may have focal deficits	🖼 MRV/CTV diagnostic; CT may be normal early; coagulation profile, screen for thrombophilia; anticoagulation therapy
❤️ Sexual Activity Headache (“Primary Sex Headache”)	💏 Sudden headache during orgasm or exertion; usually benign; recurrent; can be severe; no focal deficits	🖼 CT ± CTA on first episode to rule out SAH; MRI/MRA if atypical features or recurrent; reassurance usually sufficient
⚡ Hypertensive Crisis	💢 Severe headache with markedly raised BP; ± visual disturbance 👁, nausea; often older adults with chronic HTN	🖼 BP measurement, fundoscopy; CT/MRI if neurological deficits; urgent BP control (IV labetalol/nicardipine)
🧠 Pituitary Apoplexy	💥 Sudden severe headache, visual loss, ophthalmoplegia 👁️‍🗨️, nausea/vomiting, hypotension; often with known pituitary adenoma	🖼 MRI pituitary; hormonal panel (cortisol, thyroid, gonadotropins); urgent endocrine + neurosurgery referral; corticosteroids if hypotensive
🧩 Other / Rare	PRES (posterior reversible encephalopathy syndrome) 🧠, colloid cyst rupture 🧬, acute migraine 🌀, CNS infection 🦠; may present with thunderclap features	🖼 MRI brain; LP if infection suspected; EEG if seizure; clinical correlation essential; manage underlying cause

💡 Student Tip: Always consider SAH first in thunderclap headache. Use clinical red flags, imaging, and timing of headache to triage. Know that sexual headache is usually benign but always rule out vascular causes first.

📊 Thunderclap Headache – Urgency Table

Cause	Urgency	Notes / Student Tips
Subarachnoid haemorrhage (aneurysmal)	🔴 Life-threatening	Worst headache of life; CT <6h; LP if CT negative; neurosurgical/aneurysm repair urgently
Intracerebral haemorrhage	🔴 Life-threatening	Severe headache + focal deficits; CT head; manage BP and neurosurgical input
Cervical / intracranial artery dissection	🔴 Life-threatening	Neck pain, focal deficits, Horner’s; CTA/MRA; anticoagulation or antiplatelet as guided
Pituitary apoplexy	🔴 Life-threatening	Severe headache + visual loss, hypotension; MRI + endocrine assessment; urgent surgery if indicated
Reversible cerebral vasoconstriction syndrome (RCVS)	🟠 Urgent	Recurrent thunderclap; triggered by drugs/postpartum; CTA/MRA; usually self-limiting but monitor for stroke
Cerebral venous thrombosis (CVT)	🟠 Urgent	Thunderclap or gradual headache; seizures; MRV/CTV; anticoagulation essential
Sexual activity headache (primary)	🟡 Usually benign	Sudden headache during orgasm; rule out vascular causes first; generally recurrent but non-fatal
Hypertensive crisis headache	🟡 Usually benign but urgent if organ damage	Severe headache + markedly raised BP; check end-organ damage; CT if neurological deficit
Other rare causes (PRES, colloid cyst rupture, migraine, infection)	🟡 Usually benign / variable	Investigate as guided by clinical picture; imaging often required

💡 Tip for Students: Always treat thunderclap headache as **SAH until proven otherwise**. Use red/urgent/benign coding in exams or clinical decision-making to prioritise investigations and referral.

🔎 Key Points for Students

Always assume **SAH until proven otherwise** with thunderclap headache.
CT head is first-line; sensitivity highest within first 6 hours.
If CT negative but suspicion remains, perform **LP ≥6h after onset** to look for xanthochromia.
Sex-related primary headache is **diagnosis of exclusion**; rule out vascular emergencies first.
RCVS can mimic SAH but typically recurrent; triggers include postpartum, vasoactive drugs.
CVT and pituitary apoplexy may present similarly but have distinguishing neurological or systemic features.
Prompt **neurosurgical or neurointerventional input** is essential for aneurysmal SAH.
Monitor for **complications**: re-bleeding, vasospasm, hydrocephalus, seizures, hyponatraemia.

🧪 Suggested Investigations

Non-contrast CT head immediately for suspected SAH/ICH
CTA/MRA for aneurysm localization or arterial dissection
MRV/CTV if CVT suspected
LP if CT negative but high suspicion of SAH
Hormonal panel + MRI pituitary if apoplexy suspected
Bloods: FBC, U&E, coagulation, liver function, inflammatory markers as indicated

📚 References (UK Guidance)

💊 Acute Management (UK Guidance)

Airway, breathing, circulation; transfer to high-dependency/neuro-ICU if unstable.
Blood pressure control: SBP 140–160 mmHg before aneurysm secured (IV labetalol or nicardipine).
Analgesia: Paracetamol ± opioids; avoid NSAIDs pre-repair.
Anticoagulants/antiplatelets: Reverse if on therapy.
Nimodipine 60 mg PO/NG every 4 hours for 21 days (vasospasm prevention, per NICE and national guidance).
Definitive aneurysm repair: Early coiling or clipping (<72 hours), ideally in a tertiary neuroscience centre.
Monitor for complications: Rebleeding, hydrocephalus, vasospasm, hyponatraemia, seizures.

🩺 Supportive & Ongoing Management

Maintain euvolaemia; monitor electrolytes closely.
Neurocritical care: daily assessment, imaging for vasospasm (TCD, CTA).
Hydrocephalus: External ventricular drain (EVD) acutely, VP shunt for chronic cases.
Seizures: Treat if occur; routine prophylaxis not recommended.
Early physiotherapy, occupational therapy, and multidisciplinary team input.

📌 Teaching Points for Students

All thunderclap headaches are SAH until proven otherwise.
CT sensitivity declines after 6 hours; consider LP if negative.
Early neurosurgical involvement critical for outcome.
Nimodipine prevents vasospasm, not rebleeding.
High index of suspicion for secondary causes: RCVS, dissection, venous thrombosis.
Documentation of onset, severity, associated neurological symptoms is vital for triage.

📚 References & Guidance

NICE NG42: Headaches in over 12s – diagnosis and management
RCP: Subarachnoid haemorrhage guideline
BMA: SAH Clinical Guideline
Makindo: Saccular aneurysms
van Gijn J, Rinkel GJ. Subarachnoid haemorrhage. Brain. 2001;124:249–278.
Connolly ES et al. Guidelines for the management of aneurysmal subarachnoid haemorrhage: Stroke. 2012;43:1711–1737.

🖼 Suggested Images for Students

CT head: SAH – blood in basal cisterns, fissures, ventricles
CTA brain: saccular aneurysm at anterior communicating artery
Diagram: Circle of Willis aneurysm locations and percentages
Flowchart: Acute management pathway – airway, BP, nimodipine, aneurysm repair
CT/MRI: Complications – hydrocephalus, infarction from vasospasm

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