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Here are your easy, exam-ready notes for FMT 3rd Year MBBS on Intracranial Hemorrhages:
š§ INTRACRANIAL HEMORRHAGES
Regional Injuries Part 2 - Forensic Medicine (Marrow 8.0)
ANATOMY OF MENINGES (Quick Map)
| Space | Layer | Vessel Involved | Mnemonic |
|---|---|---|---|
| Extradural | Between skull & dura | Middle meningeal artery | Wild Arterial |
| Subdural | Between dura & arachnoid | Bridging veins | Shaken Baby |
| Subarachnoid | Between arachnoid & pia | Circle of Willis | Head ache |
1. EXTRADURAL HEMORRHAGE (EDH)
Key Facts (High Yield!)
- Least common intracranial hemorrhage
- Highest fatality
- Unilateral, coup injury
- Age group: Young adults (20-40 yrs)
Blood Vessels Involved
| Vessel | Region Injured |
|---|---|
| Middle meningeal artery (m/c) | Temporal lobe |
| Anterior ethmoidal artery | Frontal lobe |
| Transverse sinus | Occipital lobe |
| Sagittal sinus | Vertex |
Mechanism (Flow)
Blow to temporoparietal region (Pterion)
ā
Fracture of temporal bone (m/c: Fissure fracture)
ā
Rupture of middle meningeal artery
ā
Bleeding in extradural space
ā
ā Intracranial tension ā Brain compression
ā
Brainstem herniation ā Respiratory failure ā DEATH
Clinical Features ā
- 35 ml blood = Clinical features
- 150 ml blood = Fatal
- Lucid interval = Period of consciousness between episodes of unconsciousness
- Concussion ā Lucid interval ā Brain compression (d/t bleeding) ā Unconscious + death
- 3rd nerve palsy (dilated & fixed pupil + contralateral hemiparesis)
- Kernohan's notch phenomenon = Dilated pupil + Ipsilateral hemiparesis (False localising sign)
- Mechanism: Uncal herniation ā Compression of opposite area into tentorium cerebelli ā Compression of fibres in cerebral peduncle ā Ipsilateral hemiparesis + dilated pupils
Medico-legal pearl: Patient in lucid interval can provide valid evidence, make a will, and is criminally liable. Death due to failure to diagnose lucid interval = Medical negligence
Note: Lucid interval - EDH > SDH
Investigation
- NCCT brain (non-contrast CT)
- Biconvex / lentiform / lens-shaped hemorrhage
- Does NOT cross suture (most important!)
Management
- Surgical removal of clot: Craniotomy / Burr hole
2. SUBDURAL HAEMORRHAGE (SDH)
Key Facts
- Age group: Children, Elderly
- Blood vessel: Bridging veins
Types (Based on Duration)
| Type | Duration | Key Feature |
|---|---|---|
| Acute | < 3 days | Lucid interval + |
| Subacute | 3 days - 3 weeks | - |
| Chronic | > 3 weeks | Minor trauma, elderly, brain atrophy |
Mechanism
In Children:
Acceleration-deceleration injury
ā
Violent shaking
ā
Shaken Baby Syndrome ā
In Elderly:
Minor trauma
ā
Age-related brain atrophy ā ā subdural space
ā
Bridging veins lose support
ā
Bleeding with minor trauma
ā
Blood accumulates over prolonged period
ā
Chronic SDH
Clinical Features
- Headache
- Altered sensorium
- Hemiparesis ā
- Dilated & fixed pupil ā
- Personality changes
Investigation
- NCCT brain:
- Concavoconvex opacity
- Banana-shaped / Crescent-shaped hemorrhage ā
- Crosses suture (key difference from EDH!)
Management
- Conservative management
- Surgical removal of clot
Memory Aid - ABC of SDH ā
- A = Aged persons, Alcoholics
- B = Bridging veins, Boxers (Dementia pugilistica)
- C = Child abuse, Crescentic opacity
Dementia Pugilistica (Punch Drunk Syndrome)
- Seen in long-term boxers
- Most common hemorrhage: SDH
3. SUBARACHNOID HEMORRHAGE (SAH)
Causes - Mnemonic BATS ā
| Letter | Cause |
|---|---|
| B | Berry aneurysm |
| A | AV malformation |
| T | Trauma (m/c) |
| S | Stroke / Spontaneous |
Clinical Features
- Thunderclap headache (sudden onset severe headache) ā
- Nausea, vomiting
- Neck stiffness
- Drowsiness
- Loss of consciousness
- Focal neurological deficit
Investigation
- NCCT brain: Hyperdense bleeding near base of brain
- Lumbar puncture: Xanthochromia (appears 4-6 hrs after bleed) ā
Management
- Clipping / Endovascular coiling of aneurysm
QUICK COMPARISON TABLE ā
| Feature | EDH | SDH | SAH |
|---|---|---|---|
| Vessel | Middle meningeal artery | Bridging veins | Circle of Willis / Berry aneurysm |
| CT shape | Biconvex (lens) | Concavoconvex (crescent/banana) | Hyperdense near base |
| Crosses suture? | NO | YES | - |
| Lucid interval | Most common | Less common | No |
| Age group | Young adults (20-40) | Children, Elderly | Any |
| Mechanism | Coup injury, pterion blow | Shaken baby / minor trauma | Berry aneurysm rupture |
POSTMORTEM DIFFERENTIATION: SDH vs SAH ā
Pour water on the specimen:
- SDH ā Hemorrhage washed away
- SAH ā Hemorrhage persists (in sulci/subarachnoid space)
FINAL EXAM QUICK-RECALL
- EDH = Lens shaped, doesn't cross suture, lucid interval most common, m/c vessel = middle meningeal artery
- SDH = Banana/crescent shaped, crosses suture, shaken baby, bridging veins
- SAH = Thunderclap headache, xanthochromia on LP, BATS mnemonic
- Kernohan's notch = False localising sign (ipsilateral hemiparesis despite contralateral lesion)
- Dementia pugilistica = Punch drunk syndrome = SDH = long-term boxers
In tabulated form
INTRACRANIAL HEMORRHAGES - Complete Tabulated Notes
Forensic Medicine | 3rd Year MBBS
TABLE 1: OVERVIEW COMPARISON
| Feature | EDH | SDH | SAH |
|---|---|---|---|
| Full name | Extradural Hemorrhage | Subdural Hemorrhage | Subarachnoid Hemorrhage |
| Frequency | Least common | Common | Common |
| Fatality | Highest | Moderate | High |
| Age group | Young adults (20-40 yrs) | Children, Elderly | Any age |
| Vessel involved | Middle meningeal artery (m/c) | Bridging veins | Circle of Willis / Berry aneurysm |
| Space | Between skull & dura | Between dura & arachnoid | Between arachnoid & pia |
| Injury type | Unilateral, coup injury | Acceleration-deceleration / minor trauma | Spontaneous / trauma |
| Lucid interval | Most prominent ā | Present in acute only | Absent |
TABLE 2: BLOOD VESSELS INVOLVED IN EDH
| Vessel | Region of Injury |
|---|---|
| Middle meningeal artery (m/c) | Temporal lobe |
| Anterior ethmoidal artery | Frontal lobe |
| Transverse sinus | Occipital lobe |
| Sagittal sinus | Vertex (top of skull) |
TABLE 3: MECHANISM
| Type | Mechanism Steps |
|---|---|
| EDH | Blow to pterion ā Fissure fracture of temporal bone ā Rupture of middle meningeal artery ā Bleeding in extradural space ā ā ICP ā Brain compression ā Brainstem herniation ā Respiratory failure ā Death |
| SDH (Children) | Acceleration-deceleration injury ā Violent shaking ā Shaken Baby Syndrome |
| SDH (Elderly) | Minor trauma ā Age-related brain atrophy ā ā subdural space ā Bridging veins lose support ā Bleeding ā Blood accumulates ā Chronic SDH |
| SAH | Berry aneurysm rupture / AV malformation / Trauma (m/c) / Stroke / Spontaneous |
TABLE 4: TYPES OF SDH
| Type | Duration | Key Feature |
|---|---|---|
| Acute | < 3 days | Lucid interval present |
| Subacute | 3 days - 3 weeks | Intermediate |
| Chronic | > 3 weeks | Minor trauma, elderly, brain atrophy |
TABLE 5: CLINICAL FEATURES
| Feature | EDH | SDH | SAH |
|---|---|---|---|
| Headache | Yes | Yes | Thunderclap (sudden onset severe) ā |
| Lucid interval | ā Most prominent | ā Acute SDH only | ā |
| Blood volume | 35 ml = symptoms; 150 ml = fatal | - | - |
| Pupil changes | Dilated & fixed (3rd nerve palsy) | Dilated & fixed | - |
| Hemiparesis | Contralateral | Present | Focal neurological deficit |
| Neck stiffness | ā | ā | ā |
| Nausea/Vomiting | Sometimes | Sometimes | ā |
| Altered sensorium | ā | ā | ā |
| Personality changes | - | ā | - |
| Loss of consciousness | ā | ā | ā |
TABLE 6: KERNOHAN'S NOTCH PHENOMENON (EDH)
| Aspect | Detail |
|---|---|
| Also called | False localising sign |
| Sign | Dilated pupil + Ipsilateral hemiparesis |
| Mechanism | Uncal herniation ā Compression of opposite area into tentorium cerebelli ā Compression of fibres in cerebral peduncle ā Ipsilateral hemiparesis + dilated pupil |
| Why "false"? | Lesion is contralateral but signs appear ipsilateral |
TABLE 7: INVESTIGATION
| Investigation | EDH | SDH | SAH |
|---|---|---|---|
| CT scan (NCCT) | ā | ā | ā |
| Shape on CT | Biconvex / Lentiform / Lens-shaped ā | Concavoconvex / Crescent / Banana-shaped ā | Hyperdense bleeding near base of brain |
| Crosses suture? | ā NO | ā YES | - |
| Lumbar puncture | Not needed | Not needed | Xanthochromia (after 4-6 hrs) ā |
TABLE 8: MANAGEMENT
| Type | Management |
|---|---|
| EDH | Surgical removal of clot - Craniotomy / Burr hole |
| SDH | Conservative management OR Surgical removal of clot |
| SAH | Clipping / Endovascular coiling of aneurysm |
TABLE 9: CAUSES OF SAH - BATS Mnemonic
| Letter | Cause |
|---|---|
| B | Berry aneurysm |
| A | AV malformation |
| T | Trauma (m/c) |
| S | Stroke / Spontaneous |
TABLE 10: ABC OF SDH (Memory Aid)
| Letter | Associations |
|---|---|
| A | Aged persons, Alcoholics |
| B | Bridging veins, Boxers (Dementia pugilistica) |
| C | Child abuse, Crescentic opacity on CT |
TABLE 11: MEDICO-LEGAL POINTS (FMT Exam Favourite!)
| Point | Detail |
|---|---|
| Lucid interval significance | Patient is conscious, can give valid evidence, make a will, is criminally liable |
| Medical negligence | Failure to diagnose lucid interval ā Death = Medical negligence |
| Lucid interval comparison | EDH > SDH |
| Postmortem: SDH vs SAH | Pour water on specimen - SDH: hemorrhage washed away; SAH: hemorrhage persists |
| Dementia pugilistica | AKA Punch drunk syndrome; seen in long-term boxers; m/c hemorrhage = SDH |
| Shaken Baby Syndrome | SDH in children due to violent shaking (acceleration-deceleration) |
TABLE 12: FINAL HIGH-YIELD SUMMARY
| Parameter | EDH | SDH | SAH |
|---|---|---|---|
| Vessel | Middle meningeal artery | Bridging veins | Berry aneurysm / Circle of Willis |
| CT shape | š· Lens / Biconvex | š Crescent / Banana | Hyperdense at base |
| Crosses suture | ā No | ā Yes | - |
| Lucid interval | ā ā Most common | ā Acute only | ā |
| Age | 20-40 yrs | Children + Elderly | Any |
| Special sign | Kernohan's notch | Shaken baby | Thunderclap headache |
| Special test | NCCT | NCCT | LP ā Xanthochromia |
| Treatment | Craniotomy / Burr hole | Conservative / Surgery | Clipping / Coiling |
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