Head Injuries: Cerebral Concussion, Cerebral Contusion, and Cerebral Laceration

1. CEREBRAL CONCUSSION

• Occurs due to sudden acceleration/deceleration of the head (the head must be freely movable at the time of injury).
• Violent head movement causes shearing or stretching of nerve fibres and axonal damage.
• Loss of consciousness is believed to be a transient electrophysiological dysfunction of the reticular activating system (RAS) in the upper midbrain, caused by rotation of the cerebral hemispheres on the relatively fixed brainstem.
• Severe injuries occur with coronal head motion; sagittal motion produces mild/moderate injury.

• Direct violence to the head
• Indirect violence - a violent fall on feet/buttocks
• Traffic and industrial accidents (deceleration injuries are more severe than direct blows)

• Immediate loss of consciousness (lasts seconds to minutes)
• Muscles are flaccid; pupils are dilated and unreactive
• Pulse is rapid, thready; blood pressure falls
• Respiration is quick and shallow
• Temperature remains subnormal
• Amnesia (retrograde and post-traumatic) - duration proportional to severity of injury
• As consciousness returns, there is a period of automatism - the patient behaves automatically but not rationally (post-traumatic automatism)
• Mild concussion: no loss of consciousness, no confusion, amnesia may or may not be present
• Severe concussion: amnesia + loss of consciousness

• In mild/moderate cases: no macroscopic damage
• In fatal cases: no naked-eye lesions; only microscopic haemorrhages without disruption of tissue structure
• Histology shows diffuse neuronal injury with intracellular disturbances and conduction defects at synaptic junctions

• Can be ruled out if unconsciousness does not occur immediately after the blow
• The automatism phase may be misused as a defence in criminal cases ("the person committed an act without conscious awareness")

2. CEREBRAL CONTUSION

• When a localised segment of the skull undergoes deformation at the moment of impact, shear strains develop in the underlying brain tissue, producing a zone of contusion in the surface layers.
• When the head is rotated by impact, layers of brain tissue slide over each other at different depths in the cortex, damaging blood vessels.
• Produced by blunt force; may occur with or without skull fracture.

• Contusions appear as streaks or groups of punctate haemorrhages in grey and white matter
• Haemorrhage is first seen in perivascular spaces (Robin-Virchow spaces) → ring haemorrhages
• Most often found in frontal and temporal lobes; also on lateral and ventral surfaces of cerebral hemispheres
• Deeper structures (basal ganglia, midbrain, brainstem) are contused especially from impacts to the forehead and vertex
• Haemorrhages are densely arranged and elongated, pointing radially towards the white matter
• If close to the cortical surface, may cause overlying focal subarachnoid haemorrhage
• Haemorrhages also noted in the corpus callosum, 3rd ventricle, and substantia nigra of the brainstem

1. Coup contusions - beneath the area of direct impact
2. Contrecoup contusions - opposite the side of impact (due to shear strain from rotation)
3. Intermediary coup contusions - along the midbrain/brainstem between coup and contrecoup points
4. Fracture contusions - caused by skull fracture
5. Gliding contusions - in frontal/central convolutions near the upper margin of hemispheres due to stretching/shearing during to-and-fro gliding of the brain
6. Herniation contusions - in cerebellar tonsils/medulla, produced by momentary shifting of the brain toward the foramen magnum

• Ischaemic changes in neurons: within 1 hour
• Capillary proliferation: begins at 5 days, maximum at 10-12 days
• Macrophages: present in first 2 weeks
• Astrocytic proliferation: within a few weeks
• Scar formation: approximately 2 months (pale/golden yellow, depressed)

• Unconsciousness is more prolonged than in concussion (30 minutes to several days)
• Low intracranial pressure initially
• Recovery is imperfect - post-contusional state with defective memory, change of personality, confusion, irritability, delirium
• Pulse: rapid, low volume; BP reduced; respiration shallow; muscles relaxed
• On recovery: headache, photophobia, vomiting
• Cerebral irritation (develops 2-3 days post-injury, due to cerebral oedema): patient curled up in attitude of flexion, resists interference, photophobia

3. CEREBRAL LACERATION

• Stretching and shearing forces produced by blunt force
• Brain surface torn against bony ridges and edges of dural septa (falx cerebri, tentorium cerebelli)
• All penetrating injuries produce lacerations

• Inner aspect of the hemisphere (especially undersurface of frontal lobe and tip of temporal lobe)
• Lacerations often occur under skull fractures
• In depressed fractures, bone fragments physically tear into brain
• Corpus callosum and septum pellucidum (especially in younger individuals from blunt trauma without fracture)
• Pyramids at the pontomedullary junction - in severe hyperextension of the head (motor vehicle accidents), often associated with fractures of the base of skull

1. Surface lacerations - accompanied by rupture of pia mater and subarachnoid haemorrhages; usually surrounded by contusions
2. Deep lacerations - when parenchyma is completely disorganised, termed pulpyfaction; may involve ventricles
3. Contrecoup lacerations - on the side opposite the impact

• Signs and symptoms similar to cerebral contusion but more severe
• Blood enters the CSF → subarachnoid haemorrhage (CSF becomes bloodstained)
• Lacerations of the undersurface of the frontal lobe may cause anosmia (damage to olfactory nerves) and change of personality
• Deeper lacerations involving ventricles may produce large glial cysts filled with CSF (traumatic porencephalic cysts)
• Healing of surface lacerations may form adhesions between brain and dura → secondary epilepsy (due to contracting fibrous scar)
• Infants up to 5 months are particularly susceptible (easily deformable skull + very soft brain)

COMPARATIVE TABLE

Cerebral Concussion, Cerebral Contusion and Cerebral Laceration

1. CEREBRAL CONCUSSION

Definition

Mechanism

• Caused by sudden acceleration/deceleration of the head
• Shearing and stretching of nerve fibres causes diffuse neuronal injury
• Loss of consciousness occurs due to transient dysfunction of the Reticular Activating System (RAS) in the upper midbrain

Causes

• Direct blow to the head
• Indirect violence — fall on feet or buttocks
• Road traffic accidents, industrial accidents

Clinical Features

• Immediate loss of consciousness (lasts seconds to minutes)
• Muscles are flaccid
• Pupils are dilated and unreactive
• Pulse is rapid and thready; BP falls
• Respiration is shallow
• Temperature subnormal
• Amnesia — both retrograde and post-traumatic
• Post-traumatic automatism — patient appears conscious but behaves irrationally

Types

• Mild concussion — no loss of consciousness, no confusion
• Severe concussion — loss of consciousness + amnesia

Post-Concussion Syndrome

Autopsy Findings

• No macroscopic lesions in the brain
• Microscopic haemorrhages may be seen without tissue disruption
• Diffuse neuronal injury with intracellular disturbances

Medicolegal Importance

• Unconsciousness must occur immediately after injury — if it is delayed, concussion can be ruled out
• Post-traumatic automatism may be used as a defence in criminal cases

2. CEREBRAL CONTUSION

Definition

Mechanism

• Blunt force causes shear strains in the brain underlying the point of impact
• Rotation of the head causes layers of brain tissue to slide over each other, damaging blood vessels
• May occur with or without skull fracture

Pathology

• Appears as punctate (pin-point) haemorrhages in grey and white matter
• Ring haemorrhages — bleeding into perivascular spaces of Robin-Virchow
• Haemorrhages seen in corpus callosum, 3rd ventricle, and substantia nigra of brainstem
• Most common in frontal and temporal lobes

Types

Clinical Features

• Unconsciousness — more prolonged (30 minutes to several days)
• Recovery is imperfect — defective memory, personality change, confusion, irritability
• Headache, photophobia, vomiting on recovery
• Cerebral irritation (2-3 days after injury): patient lies curled up, flexed posture, resists interference

Autopsy — Age of Contusion

• 1 hour — ischaemic neuronal changes
• 5 days — capillary proliferation begins
• 10-12 days — capillary proliferation maximum
• 2 weeks — macrophages with fat
• Few weeks — astrocytic proliferation
• 2 months — scar formation (pale/golden yellow, depressed)

3. CEREBRAL LACERATION

Definition

Mechanism

• Shearing and stretching forces from blunt trauma
• Brain surface tears against bony ridges and edges of dural septa (falx cerebri, tentorium)
• All penetrating injuries produce laceration
• In depressed fractures, bone fragments are driven into brain

Common Sites

• Undersurface of frontal lobe
• Tip of temporal lobe
• Corpus callosum
• Pontomedullary junction — in severe hyperextension of head (road accidents)

Types

• Surface laceration — pia mater torn, subarachnoid haemorrhage, surrounded by contusions
• Deep laceration — complete disorganisation of parenchyma = pulpyfaction
• Contrecoup laceration — on the opposite side of impact

Clinical Features

• Symptoms similar to contusion but more severe
• Blood enters CSF → subarachnoid haemorrhage (bloodstained CSF)
• Laceration of frontal lobe → anosmia + change of personality
• Traumatic porencephalic cysts — deep lacerations involving ventricles heal to form large glial cysts filled with CSF
• Secondary epilepsy — adhesions between brain and dura form at healed laceration sites

Special Points

• Common in infants under 5 months (soft brain + easily deformable skull)
• Lacerations at the pontomedullary junction in hyperextension injuries are often fatal

COMPARISON TABLE (Important for Exam)

Key Line to Remember: Concussion = No damage, Contusion = Bruising (haemorrhage, no tear), Laceration = Tearing Pia intact in contusion; Pia torn in laceration.

Cerebral Concussion, Cerebral Contusion and Cerebral Laceration

INTRODUCTION

1. CEREBRAL CONCUSSION

Definition

Mechanism

• Sudden acceleration/deceleration of head
• Shearing of nerve fibres → diffuse neuronal injury
• Reticular Activating System (RAS) in upper midbrain is transiently disrupted → loss of consciousness

Clinical Features

• Immediate loss of consciousness (seconds to minutes)
• Flaccid muscles, dilated unreactive pupils
• Pulse rapid and thready, BP falls
• Respiration shallow, temperature subnormal
• Retrograde and post-traumatic amnesia
• Post-traumatic automatism (acts without awareness)

Investigations

Management

• Maintain clear airway
• Control breathing and circulation (ABC)
• Do not move the patient without cervical spine precautions
• Control scalp bleeding with pressure bandage

• Admit for observation (minimum 24 hours)
• Monitor: GCS, pulse, BP, respiration, pupils every hour
• CT scan of brain to rule out intracranial haemorrhage
• IV line with normal saline (avoid free water/hypotonic fluids)
• Oxygen supplementation
• Analgesics for headache - paracetamol or NSAIDs
• No sedatives (mask neurological signs)
• Instruct patient/family to return if: worsening headache, vomiting, confusion, or difficulty arousing

• Physical and cognitive rest
• Gradual return to activity
• Avoid contact sports until fully recovered
• Written instruction sheet with warning signs

2. CEREBRAL CONTUSION

Definition

Pathology

• Punctate/ring haemorrhages in grey and white matter
• Perivascular bleeding (Robin-Virchow spaces)
• Most common in frontal and temporal lobes
• May involve corpus callosum, substantia nigra of brainstem

Clinical Features

• Unconsciousness - more prolonged (30 min to several days)
• Pulse rapid, low volume; BP reduced; respiration shallow
• Recovery is imperfect - memory loss, personality change, confusion, irritability
• On recovery: headache, photophobia, vomiting
• Cerebral irritation (2-3 days later): patient curled up, resists interference, photophobia

Investigations

Management

• ABC - Airway, Breathing, Circulation
• Cervical spine immobilisation
• Endotracheal intubation if necessary (GCS < 8)
• IV access - infuse normal saline (avoid hypotonic fluids)
• Maintain systolic BP > 90 mmHg (hypotension doubles mortality)
• Oxygen - maintain arterial oxygen saturation at normal levels

• Head elevation at 30 degrees (reduces ICP)
• Hyperventilation - lowers PaCO2 → decreases intracranial oedema (short-term)
• Mannitol 20% (0.25-1 g/kg IV) - hyperosmolar therapy to reduce cerebral oedema
• Hypertonic saline - alternative to mannitol for reducing ICP
• Steroids - dexamethasone (action is delayed; limited role in trauma)
• Anti-epileptics - prophylaxis to prevent post-traumatic seizures (phenytoin)
• Urinary catheterisation if needed; monitor urine output
• Temperature, pulse, BP, respiration, pupils charted every hour

• If haematoma or mass effect develops → surgical evacuation
• Decompressive craniectomy in refractory raised ICP

3. CEREBRAL LACERATION

Definition

Mechanism

• Shearing forces; brain torn against bony ridges and dural septa
• Depressed skull fracture driving bone into brain
• All penetrating injuries
• Severe hyperextension of head (pontomedullary junction tears)

Sites

• Undersurface of frontal lobe, tip of temporal lobe
• Corpus callosum
• Pontomedullary junction - in hyperextension injuries

Clinical Features

• Most severe - signs similar to contusion but worse
• Subarachnoid haemorrhage - blood enters CSF
• Bloodstained CSF on lumbar puncture
• Laceration of frontal lobe → anosmia + personality change
• Deep lacerations → traumatic porencephalic cysts
• Healed lacerations → secondary epilepsy (brain-dura adhesions)

Investigations

Management

• Full ATLS protocol - Airway, Breathing, Circulation
• Endotracheal intubation (GCS usually < 8)
• IV normal saline; avoid hypotonic fluids (worsens cerebral oedema)
• Immediate CT brain to assess extent of laceration and haematoma

• Same as contusion + more aggressive ICP control
• Mannitol / Hypertonic saline for raised ICP
• Avoid: hypoxia, hypercarbia, hyperthermia, awkward neck positions (all raise ICP)
• Anti-epileptics (phenytoin or levetiracetam) - mandatory
• Nutritional support (NGT feeding in unconscious patients)
• Bladder catheterisation; monitor fluid balance

• Evacuation of haematoma if significant (epidural, subdural, intracerebral)
• Debridement of wound in penetrating/depressed fractures
• Decompressive craniectomy if ICP is refractory to medical management
• Repair of dural tear to prevent CSF leakage and infection

COMPARISON TABLE

Key line to remember for exam: Concussion = No damage → rest and observe Contusion = Bruise (haemorrhage without tear) → CT + medical management Laceration = Tear (pia torn, subarachnoid bleed) → CT + surgery often needed