Pathology OSPE Flashcards
Normal peripheral nerve
Normal myelinated axons
The red arrow is mesaxon
Basically there is a cross-reaction of AB with the antigen for the infection that occured previously and now they are reacting with myelin sheath antigens and that causes immune complexes so there are now macrophages (and schwann cells) there trying to engulf all the debri.
The myeline will eventually be carried away by the Schwann and macrophages
The hyperglycaemia in axons will give rise to advanced glycosylation etc, so there is damage to the axon and also the schwann cell for the same reason. The arteries are also affected and will lose the BS so ischaemic damage also occurs in diabetics’ nerves
Pathogenesis:
You lose the properioception in foot due to the loss of the nerves and this will lead to loss of pain sensation too. This also means you can get infection quickly - bacteria love the hyperglycaemic regions as well. The hyperglycaemia also adversely affects neutrophils so makes everything worse.
Aka, ulcer bc lack of BS and no sensory info
ALS (motor neurons affected, not sensory)
ALS - neurogenic atrophy = amyotrophy (loss of muscle due to neuron cell death)
The corticospinal tract goes both in the lateral (contralateral fibres that do cross) and anterior (ipsilateral fibres that don’t cross) regions of the spinal cord
Clot looks slightly older - because there’s also some adherent to the dura itself, which suggests there has been some form of organisation so fibrosis already occuring (hence why it is also lighter?)
The pigment in the middle of the dura is the macrophages breaking down haemoglobin
Most likely to be the middle meningeal artery if you’re having an epidural bleed
What kind of vessels lead to
- Epidural haemorrhages
- Subdural haemorrhages
- Subarachnoid haemorrahges
- Epi = middle meningeal artery (runs through the periosteal layer of the dura - comes through the foramen spinosum). Since arterial, get symptoms in few hours. The arterial blood pressure will also strip the periosteal part of the dura away from the skull. See the biconvex shaped haematoma because it is limited by the suture lines (the periostal part of the dura must attach there).
- Subd = most likely the bridging veins that piece the arachnoid and meningeal part of the dura to get to the sinuses - since veins, blood oozes and will take days to notice. See the sickle shaped haematoma on the CT (not as hyper dense as epidural haem. because the iron in Hb will be starting to be reasbrobed). The blood can pass all around the area - not limited by the sutures.
- Subarachnoid - the cerebreal vessels that run in this space. Just know that thunderclap headache is the sign of a subarachnoid bleed and will see a star/dancing man on CT
In the close up, can see the petechial haemorrahges
Extensive axonal damage (diffuse axonal injury) is thought to explain immediate and prolonged coma following severe head injury
Try to label this (it is normal)
So this one has the cerebral edema and lots of injuries like brain laceration, bleeding into the ventricles (intraventricular haemorrhage), and petechial haemorrhages + diffuse axonal injury
Retraction balls are accumulations of the proteins and organelles at the proximal stump because the stump has short of closed in on itself but the cell body is still producing things (usually won’t do too much damage bc don’t get big enough
