Anatomy of blood vessels on the surface of the brain

Transcription

1 Anatomy of blood vessels on the surface of the brain Delicate surface draining veins are found in the subarachnoid space. Rupture of these vessels will cause subarachnoid bleeding. Bridging veins are few in number and carry huge volumes of blood. Rupture will not lead to a thin film bleed, but to a large space occupying clot. Lateral DSA

2 There is no subdural space. The diagram on the right is anatomically incorrect. The brain depicted is that of an adult. Draining veins are found in the subarachnoid space.

3 The delicate cortical draining veins are in the subarachnoid space; rupture would lead to subarachnoid bleeding (Duhaime 1998) The BV cross the arachnoid barrier membrane and enter the dura over a few microns. As they enter the dura they have a thick muscle cuff. There is no weak point here. This muscle cuff probably controls venous blood flow from the brain. Smooth muscle actin

4 BV carry huge amounts of blood 55ml per 100g per min~400 ml per minute in baby of this age If half of the blood drains via BV then ~200 ml per minute pass through them. This will cause a massive space occupying bleed, not a thin film

5 If a BV is ruptured at the junction with the dura a large spaceoccupying clot will result. 1 year old fell from top bunk bed. Note large right sided mass of blood clot.

6 A healing subdural bleed may be difficult to see on routine scans. If contrast is given the reactive newly formed blood vessels are seen Fresh bleeding is common in healing subdural haemorrhages

7 HE and CD34 A 5 month old healing subdural membrane (M) beneath the dura (D). There is a small fresh bleed in the subdural edge. A special marker of blood vessels shows them as brown rings in the free edge of the healing blood clot. They are thin walled and bleed easily without trauma. CD34

8 Dura Dura Healing subdural membrane The microscope section of M s dura shows a healing subdural membrane, marked with a black arrow in these pictures. The high power picture on the right shows the healing membrane with new, fragile blood vessels stained brown with CD31 (arrowheads)

9 A lower power picture (top) shows the extensive healing membrane with delicate blood vessels stained brown (CD31) Dura In the lower picture the blue stain (Perl s) is old, altered blood, in the healing membrane, Evidence of earlier bleeding

10 Free fresh blood cells in subdural compartment D D High power picture (H&E) of the dura shows the fibres of the dura (pink) separated by fresh bleeding (dark pink). Blood is leaking out into the subdural compartment (top)

11 Baby Z :fresh bleeding into healing subdural membrane

12 Opening the skull Parasaggittal cut will allow visualisation of the bridging veins in young babies

13 In older babies and adults the brain is removed in the dura so that BV can be examined later It is important to examine dural sinuses for thrombosis

14 Diagram of the eye within the eye socket. Note how it is protected by bone and padded with fat (yellow) and muscle.

15 Diagram of the eye. The eye is in continuity with the brain and has the same membranous coverings Inside the dura Outside the dura Dura Subarachnoid space in continuity with brain SA space

16 Diagram of midline slice through brain and spinal cord. The cervicomedullary junction is the point at which the brain hinges on the neck when the head moves forwards and backwards (flexion and extension of the neck). It is at this pint that traumatic axonal injury has been described in 1/3 of infants following inflicted injury (Geddes 2001)

17 Beta APP Nerve fibre damage was described in two well defined bundles of the lower medulla (Geddes 2001)and in nerve roots in the neck (Shannon 1998). A more recent study could not identify traumatic axonal damage in infants and concluded that the axonal injury was all due to oxygen deprivation (Oehmichen 2008).

18 Non traumatic axonal injury spinal nerve roots 2 year old drowning Beta APP 3 month cardiac arrest post cardiac surgery

19 Diagram of adult throat showing epiglottis. When intubating a baby the tube has to pass over and behind the epiglottis to maintain an airway.