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IM17.1-14 | Headache — PBL Case

CLINICAL SETTING

Dr Arvind, a senior resident in the Emergency Medicine department of a tertiary teaching hospital in Chennai, is supervising a group of four final-year MBBS students on their emergency posting. It is 11 PM on a Saturday. The triage nurse calls: 'Doctor, 38-year-old male, walk-in, severe headache, brought in by his wife. She says he collapsed briefly at home.' The students gather around the workstation. Mr Ramesh Iyer, a 38-year-old software engineer with no significant past medical history, is escorted to the resuscitation bay. His wife is anxious: 'He was fine, then while straining at the toilet, he suddenly clutched his head and said it felt like something exploded inside. He has never had headaches before.' Mr Iyer is sitting upright, alert, and oriented. He is in obvious distress. Vital signs: BP 168/98 mmHg, pulse 88/min regular, RR 16/min, temperature 36.8°C, SpO2 99% on air. He describes the headache as the worst pain he has ever felt in his life, started 2 hours ago and reached its maximum intensity within 2 seconds. The students look at their notes and one writes: 'Severe headache — possible migraine?'

Trigger 1: First Assessment: The Students Reach for a Migraine Diagnosis

The most vocal student, Meena, says: 'He has no prior headache history, so this could be his first migraine attack. He is only 38 — the classic age. Blood pressure is a bit high but he is in pain. I would give him sumatriptan and paracetamol.' Dr Arvind pauses and asks the group: 'Before you prescribe anything, what is the single most important characterisation of this headache that you have not yet fully explored?' The students review their notes. One points to the phrase 'reached maximum intensity within 2 seconds.' Another notes: 'He said something exploded inside.' Dr Arvind says: 'What does that pattern tell you? And is this man's headache compatible with his first-ever migraine attack?' Mr Iyer adds unprompted: 'I was straining to pass stool when it happened. I have never had anything like this.'

DISCUSSION POINTS

  • What is thunderclap headache, and what is the clinical definition in terms of onset-to-peak timing? Which SNNOOP10 red flag does this represent?
  • Why is a first-ever severe headache in a 38-year-old man NOT safely attributed to migraine, even if the pain character superficially resembles migraine?
  • What does the Valsalva trigger (straining at toilet) suggest about the possible underlying aetiology?
Click to reveal Trigger 2: The Investigation Plan: CT Head and the 6-Hour Window (discuss previous trigger first!)

Trigger 2: The Investigation Plan: CT Head and the 6-Hour Window

Dr Arvind orders an urgent non-contrast CT head. The radiologist calls back 40 minutes later: 'CT is normal. No hyperdense areas in the basal cisterns. No mass effect. Report finalised as normal CT head.' Meena says: 'Normal CT — it is not SAH. Now we can proceed with migraine treatment.' A second student, Kiran, hesitates: 'Wait — how long ago did the headache start? His wife said it started 2 hours ago. Does the timing affect the CT result?' Dr Arvind asks: 'At what time point after the ictus does CT sensitivity for SAH begin to fall significantly, and what does that mean for this patient's management?' Mr Iyer's wife interjects: 'He was in the bathroom for about 30 minutes before calling me. It might have been longer than 2 hours.' A nurse notes: 'The LP trolley is set up in bay 3.'

DISCUSSION POINTS

  • What is the approximate sensitivity of non-contrast CT head for subarachnoid haemorrhage at 6 hours, 12 hours, 24 hours, and 1 week after ictus? How does this sensitivity profile affect your interpretation of a normal CT in this case?
  • What is xanthochromia, how is it detected, and at what time point after SAH should LP be performed to maximise the yield for xanthochromia detection?
  • How do you differentiate a traumatic tap from true SAH on CSF analysis? Describe the specific CSF findings in each scenario.
Click to reveal Trigger 3: The LP Result: Confirming the Diagnosis (discuss previous trigger first!)

Trigger 3: The LP Result: Confirming the Diagnosis

LP is performed at L3–L4 at 14 hours after estimated ictus. Procedure is uncomplicated. Opening pressure: 220 mmH2O. CSF appearance: clear. Results from laboratory: tube 1 — RBC 1800/mm3, WBC 8/mm3 (100% lymphocytes); tube 4 — RBC 1750/mm3, WBC 6/mm3. Protein 82 mg/dL. Glucose 64 mg/dL (blood glucose 96 mg/dL). Spectrophotometry: xanthochromia detected (bilirubin peak). Gram stain: no organisms. Dr Arvind gathers the students: 'Now interpret this CSF report in full. What is the diagnosis, and what is the immediate next step in management?' Mr Iyer's wife is in the consultation room; she knows he has been admitted for tests. She asks a nurse: 'Is it something serious?'

DISCUSSION POINTS

  • Interpret the CSF findings: what features support the diagnosis of subarachnoid haemorrhage rather than a traumatic tap? What role does spectrophotometry play in distinguishing the two?
  • Given confirmed SAH, what is the next imaging investigation required, and what is it looking for? What is the management sequence in the next 24 hours?
  • What is the significance of the blood pressure (168/98 mmHg) in the context of SAH? Should it be aggressively lowered immediately? What are the risks of over-treatment and under-treatment of blood pressure in acute SAH?
Click to reveal Trigger 4: Counselling the Family and The Learning Moment (discuss previous trigger first!)

Trigger 4: Counselling the Family and The Learning Moment

Mr Iyer is admitted to the neurosurgical unit and CTA of the circle of Willis confirms a 7 mm aneurysm at the junction of the posterior communicating artery and internal carotid artery. He is scheduled for elective coil embolisation in 24 hours. His wife asks to speak to the medical students who were present at the initial assessment: 'Can you explain to me what happened, why he had this headache, and whether the doctors almost missed it?' Meena, who initially suggested sumatriptan, reflects on her initial clinical reasoning error. Dr Arvind asks the group to discuss the systems and clinical reasoning issues that this case illustrates, and then to debrief: 'If Meena had given sumatriptan and sent him home, what would have happened?' The group is quiet.

DISCUSSION POINTS

  • What is the pathophysiology of the thunderclap headache in subarachnoid haemorrhage: why does the headache reach maximal intensity within seconds?
  • What is the SNNOOP10 mnemonic, and which specific items were triggered by this presentation? How should a structured red-flag screen have changed the initial differential diagnosis?
  • Construct a safe discharge protocol for a patient presenting with a severe headache that is NOT the worst headache of their life and has no red flags: what criteria must ALL be met before discharge?

Group Task Assignments

  • Construct a complete SNNOOP10 red-flag assessment for Mr Iyer's presentation, documenting each of the 10 items as present, absent, or unknown, and explaining what action is triggered by each positive finding.
  • Design a decision algorithm for a headache patient arriving in the emergency department: (a) thunderclap onset — what is the mandatory investigation sequence? (b) progressive headache over weeks with papilloedema — what investigation and why? (c) headache with fever and meningism — management sequence without LP delay? (d) bilateral pressing headache with no red flags — ICHD-3 classification and outpatient management.
  • Debate the following proposition: 'A normal non-contrast CT head performed within 6 hours of ictus is sufficient to exclude subarachnoid haemorrhage and LP is unnecessary.' What is the evidence for and against this statement?
  • Write a discharge safety-netting note for a patient who presented with a first-ever severe headache that was fully worked up (CT and LP both negative at 12 hours) and was concluded to be a primary thunderclap headache variant. What must the note include about return-to-emergency criteria?

Learning Issues

Research these questions and bring your findings to the discussion.

  1. [IM17.1] How is headache classified by the ICHD-3, and what are the distinguishing clinical features that separate primary headache (migraine, TTH, cluster) from secondary headache (SAH, meningitis, raised ICP)?
  2. [IM17.6] What is the correct imaging strategy for thunderclap headache: which modality is used first, what is its sensitivity at different time points after ictus, and when is LP required after a negative CT?
  3. [IM17.7] What are the indications and contraindications for lumbar puncture in headache, and how is the correct level and technique for LP in an adult determined?
  4. [IM17.9] How is xanthochromia detected in CSF and distinguished from a traumatic tap? What are the characteristic CSF profiles for SAH, bacterial meningitis, viral meningitis, and TBM?
  5. [IM17.10] What are the indications for emergency hospital admission in a patient presenting with headache, and what constitutes the immediate supportive care bundle for suspected SAH and bacterial meningitis?