Subarachnoid Hemorrhage (SAH)

Definition

Etiology

Clinical Features

• Thunderclap headache - "worst headache of my life," peaks in seconds to minutes
  • Headaches peaking >60 minutes after onset are unlikely to be SAH
• Syncope (may be the initial manifestation)
• Nausea, vomiting
• Neck stiffness, photophobia
• Seizures
• Sentinel headache - up to 1/3 of patients recall a milder headache days to weeks prior
• Focal neuro deficits in up to 20% (e.g., CN III palsy from posterior communicating artery aneurysm causing pupillary dilation)
• ~50% have altered or fluctuating consciousness

Grading

Hunt and Hess Scale

Diagnosis

• Sensitivity ~100% within first 3 days; drops to ~50% by end of week 1
• Within 6 hours of onset, sensitivity approaches near-100% on modern multidetector CT

• Elevated RBC count
• Xanthochromia - detectable ~2 hours post-hemorrhage, persists for weeks

• CTA or MRA to identify and characterize the aneurysm
• If CTA is negative with clear SAH: four-vessel conventional catheter angiography with 3D reconstruction is mandatory
• If 4-vessel angio and CTA both negative: six-vessel angiography (including external carotid) to rule out dural fistula

• Age ≥40
• Neck pain or stiffness
• Loss of consciousness
• Onset during exertion
• Thunderclap (instantly peaking) headache
• Limited neck flexion on exam

Differential Diagnosis

• Cervical artery dissection
• Cerebral venous thrombosis
• Reversible cerebral vasoconstriction syndrome
• Hemorrhagic or ischemic stroke
• Migraine, cluster headache
• CNS infection (meningitis) - distinguished by fever and slower onset

Management

Immediate priorities

Definitive treatment of the aneurysm

• Endovascular coil embolization is generally preferred over neurosurgical clipping
• Choice depends on aneurysm size, location, morphology, and local expertise

Disposition

Prognosis

• ~10% die before reaching hospital; another ~10% die prior to hospital evaluation
• Overall mortality: 40-50%
• ~1/3 of survivors have functional and cognitive deficits
• WFNS Grade V (GCS 3) still carries ~22% good outcome rate in some studies
• Rebleeding with coma: 50% mortality
• Bilateral pupillary loss: ~95% mortality

Neck Position in Tubercular Meningitis (TBM)

Short Answer

Understanding the Terminology

Nuchal Rigidity - The Correct Sign

• Kernig's sign - Pain in the hamstrings when knees are straightened with hips flexed at 90°
• Brudzinski's sign - Passive flexion of the neck causes spontaneous flexion of the hips and knees

Why the Confusion About "Extension"?

• The neck is hyperextended (bent backward)
• The back is arched
• The knees may be drawn up

Clinical Features of TBM Specifically

• Subacute onset - symptoms evolve over 1-2 weeks (not hours like pyogenic meningitis)
• Early symptoms: low-grade fever, malaise, headache (>50%), lethargy, confusion, stiff neck (75%)
• In young children and infants: stiff neck may be absent - apathy, hyperirritability, vomiting, and seizures predominate
• Cranial nerve palsies (especially ocular palsies) in ~20%
• Signs of raised ICP: papilledema, CN VI palsy, deteriorating consciousness

Summary

"Nuchal rigidity ('stiff neck') is the pathognomonic sign of meningeal irritation and is present when the neck resists passive flexion." - Harrison's Principles of Internal Medicine 22e

"Stiff neck (75% of cases), with Kernig and Brudzinski signs. Characteristically, these symptoms evolve much less rapidly in tuberculous than in bacterial meningitis." - Adams and Victor's Principles of Neurology, 12e

25G Quincke (Standard Spinal) vs. 25G Pencil-Point Needle

Side-by-Side Comparison

Key Point: Why the Same Gauge Behaves Differently

"The incidence of headache is reduced with the use of pencil-point needles (Whitacre or Sprotte), compared with cutting bevel (Quincke) spinal needles."

• Barash's Clinical Anesthesia 9e

"The introduction of blunt tip (pencil-point) needles has markedly decreased the incidence of post-dural puncture headache."

• Morgan & Mikhail's Clinical Anesthesiology 7e

1. The rounded tip separates rather than cuts dural fibers
2. The jagged hole left by a pencil-point needle triggers a stronger local inflammatory response → edema → better closure of the dural defect

PDPH Incidence by Needle Type & Gauge

Types of Pencil-Point Needles

Clinical Bottom Line

• Both are 25G - so the dural hole size is identical
• The key difference is tip geometry and dural entry mechanism
• Pencil-point is preferred for spinal anesthesia and obstetric patients (higher PDPH risk)
• Use a 25G pencil-point over 25G Quincke whenever PDPH prevention is the priority
• For diagnostic LP where CSF pressure measurement is needed, a 20-22G atraumatic needle is the best overall choice (25G can be too floppy and slow for adequate flow)