Extradural, subdural and subarachnoid haemorrhage
How bleeding outside the brain differs by compartment: arterial extradural clots with a lucid interval, venous subdural crescents that grow over weeks, blood in the CSF after aneurysm rupture, germinal matrix bleeds in preterm babies, and how blood ages.
By the end, you can
- Relate the attachments of the dura and arachnoid to the source, shape and spread of extradural and subdural haematomas.
- Explain the lucid interval of an extradural haematoma and why a chronic subdural haematoma enlarges over weeks.
- Explain how blood in the subarachnoid space causes chemical meningitis, hydrocephalus and vasospasm.
- Explain why germinal matrix haemorrhage affects preterm babies and how it is graded.
- Describe how blood changes with time on CT and in the tissue, and explain how the main treatments act on each kind of bleed.
What it is
Bleeding inside the skull but outside the brain substance is named by the compartment it fills. An extradural (epidural) haematoma lies between the skull and the dura, a subdural haematoma between the dura and the arachnoid, and subarachnoid haemorrhage in the cerebrospinal fluid (CSF) under the arachnoid. In preterm babies, bleeding from the germinal matrix beside the lateral ventricles often extends into them (intraventricular haemorrhage). Each has a typical source, shape and course.
4 types to tell apart
- Extradural haematoma
- Usually arterial, from the middle meningeal artery torn by a skull fracture; lens-shaped and fast-growing.
- Subdural haematoma
- Venous, from torn bridging veins; crescent-shaped. Acute after severe injury, chronic over weeks in older people.
- Subarachnoid haemorrhage
- Blood in the CSF: from head injury overall, and mostly from a ruptured saccular aneurysm when spontaneous.
- Germinal matrix and intraventricular haemorrhage
- Bleeding from fragile vessels beside the lateral ventricles of preterm babies, often into the ventricles.
US spelling: haemorrhage → hemorrhage, haematoma → hematoma.
Normal function
Bone, dura, arachnoid and the spaces between
Inside the the brain is wrapped in three membranes. The tough is fused to the inner surface of the bone, most firmly along the sutures. The runs between bone and dura in a groove of the inner table, where the side of the skull is thinnest. Normally there is no space here: an extradural space appears only when blood forces the dura off the bone.
The thin lies against the inner surface of the dura. The junction between them is a weak plane rather than an open space, and it is crossed by bridging veins that carry blood from the brain surface to the dural venous sinuses, such as the . They are tethered between a brain that can move slightly inside the skull and a sinus fixed to it.
Under the arachnoid, the subarachnoid space holds CSF and the large arteries of the arterial circle; CSF flows through it and is absorbed into the sinuses through the arachnoid granulations. Before birth there is one more vulnerable site, inside the brain: the germinal matrix, a layer of dividing precursor cells under the lining of the lateral ventricles.
Underlying change · Step 1 of 5
Extradural: arterial blood strips dura from bone
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Underlying change · Step 2 of 5
Subdural: torn bridging veins, acute or chronic
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 5
Subarachnoid: blood mixed into the CSF
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 4 of 5
Germinal matrix: bleeding in the preterm brain
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 5 of 5
How the blood changes with time
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .