H&N5 - Meninges, Dural Folds & Dural Venous Sinuses

Question 1

3 layers of the meninges

Dura Mater
Arachnoid Mater
Pia Mater

Answer 1

1. ) Dura - tough fibrous membrane containing 2 layers:
   - periosteal layer fuses with periosteum lining inner table of skull bones
   - meningeal layer is adjacent to the arachnoid
2. ) Arachnoid - soft translucent membrane
   - subarachnoid space contains CSF and vessels
   - arachnoid granulations project into the dura
   - arachnoid trabeculae connect the arachnoid and pia
3. ) Pia Mater- thin layer adhered closely to the brain
   - it is pierced only by blood vessels
   - contains choroid plexus producing CSF

Question 2

4 structures in the dura

Dural Venous Sinuses
Dural Folds
Briding Veins
Emissary Veins

Answer 2

1. ) Dural Venous Sinuses - venous channels in brain
   - formed when the 2 layers of the dura are separated
   - eventually drains into the IJV
2. ) Dural Folds - rigid dividers/stabilisers of the brain
   - formed when 2 separated meningeal layers fuse
   - falx cerebri (longitudinal), falx cerebelli (cerebellum)
   - tentorium cerebellli (transverse)

3.) Bridging Veins - connects DVS to cerebral veins within the subarachnoid space

4. ) Emissary Veins - connects DVS to extracranial veins
   - they traverse through the skull

Question 3

Name 9 DVS and their general locations

Answer 3

1. ) Superior Saggital Sinus (SSS) - along margin of falx cerebri
2. ) Inferior Saggital Sinus (ISS) - underneath SSS
3. ) Cavernous Sinus - on either side of the sella turcica
4. ) Superior Petrosal - runs along the top of the petrous bone
5. ) Inferior Petrosal - runs along the bottom of the petrous bone
6. ) Straight Sinus - drains into confluence
7. ) Confluence of Sinuses - where all DVS converge at the central posterior aspect of the skull
8. ) Transverse Sinus - connects confluence to sigmoid
9. ) Sigmoid Sinus - connects transverse to IJV

Question 4

4 features of a subaponeurotic haemorrhage

Location
Type of Bleed
Symptoms
Examination

Answer 4

1. ) Location - bleed into the layers of the scalp
   - NOT AN INTRACRANIAL HAEMORRHAGE
2. ) Type of Bleed - arterial bleed often due to damage to the superficial temporal artery
3. ) Symptoms - no signs of confusion
4. ) Examination - will see superficial bleeding

Question 5

5 features of an extradural haemorrhage

Location
Type of Bleed
Common Mechanism
Symptoms
Examination

Answer 5

1. ) Location - between the periosteal and meningeal layer of the dura
2. ) Type of Bleed - arterial bleed
3. ) Common Mechanism - due to trauma at pterion damaging MMA
4. ) Symptoms - initial loss of consciousness (lucid interval), then confusion occurs hours later (due to increasing compression of the brain)
5. ) Examination - CT Scan
   - lens/lemon shaped haemorrhage on CT

Question 6

5 features of a subdural haemorrhage

Location
Type of Bleed
Common Mechanism
Symptoms
Examination

Answer 6

1. ) Location - between the meningeal layer and the arachnoid
2. ) Type of Bleed - venous blood from bridging veins
3. ) Common Mechanism - occurs in elderly due to to cerebral atrophy causing tension on bridging veins
   - dementia increases the risk since it shrinks the brain

4.) Symptoms - confusion with previous history of mild head injury because it takes time to see symptoms because venous blood bleeds slower

5. ) Examination - CT Scan
   - banana shaped (crescentic) haemorrhage on CT
   - may or may not include a midline shift
   - midline shift –> neurological abnormalities

Question 7

5 features of a subarachnoid haemorrhage

Location
Type of Bleed
Common Mechanism
Symptoms x8
Examination

Answer 7

1. ) Location - between the arachnoid and pia
   - blood leaks into CSF –> meningism symptoms

2.) Type of Bleed - arterial bleed due to damage to branch of CoW (posterior communicating artery)

3. ) Common Mechanism - trauma or aneurysm rupture
   - berry aneurysms accounts for 80% of non-traumatic
4. ) Symptoms - present straight away, no latent period
   - thunderclap headache, dizziness, N/V
   - orbital pain, diplopia, visual loss
   - photophobia and neck stiffness (meningism)
   - often get high blood pressure as well
   - differs from meningitis because its sudden and no fever symptoms
5. ) Examination - CT Scan
   - blood accumulates in basal cistern, star sign
   - xanthochromia (RBC degeneration) in CSF suggests SAH occurred > 12 hrs ago

Question 8

4 sequelae of a subarachnoid haemorrhage

Vasospasm
Cerebral Oedema
Acute Hydrocephalus
Embolus

Answer 8

1. ) Vasospasm - vasconstriction (due to CSF irritant)
   - can lead to global cerebral ischaemia
2. ) Cerebral Oedema
   - a response to hypoxia and extravasated blood
3. ) Acute Hydrocephalus - blood in subarachnoid space may block normal drainage of CSF
4. ) Embolus - thrombi occludes smaller distal arteries

Question 9

2 treatments for a subarachnoid haemorrhage

CCBs
Surgery x2

Answer 9

1. ) Calcium Channel Blockers (CCBs) - Nimlodipine
   - prevents vasospasm and secondary ischaemia
2. ) Surgery - prevents re-bleeding
   - clipping: clamping neck of aneurysm
   - coiling: insertion of wire into aneuysm sac causing thrombosis of blood within the aneurysm

Question 10

2 signs to diagnose meningitis

Kernig’s Sign
Brudzinski Sign

Answer 10

1. ) Kernigs’s Sign
   - supine patient with thigh flexed to 90 degrees
   - positive when knee extension is met with resistance
2. ) Brudzinski Sign
   - flexion of neck produces an involuntary flexion of knees and hips

Question 11

3 features of brain aneurysms

Definition
Common Locations
Risk Factors

Answer 11

1.) Definition - enlargement of an artery cause by weakness of an arterial wall

2. ) Common Locations - usually at bifurcation points
   - large arteries in anterior CoW is most common
   - aneurysm in the posterior communicating artery —> CNIII palsy
3. ) Risk Factors - same as cardiovascular
   - hypertension, smoking, alcohol etc.
   - others: CT disorders, PCOS