Lucid interval in Epidural Hematoma

Yesterday a friend asked me,"why is there lucid interval in epidural hematoma?

The answer lies in the anatomy and the blood vessels involve.

My explaination:
Epidural hematoma occurs when blood accumulate in the interface between the dura matter and the skull.
It usually involve the middle meningeal artery which is located in the interface.
When this artery rupture due to trauma or what not, blood will start oozing out. Being arterial, the blood pressure of course will be higher than those of venous origin
Immediately after trauma, patient(or should i say victim) is unconcious due to the impact of the trauma. He then regain conciousness and complain of nothing.
In his head, the middle meningeal artery have ruptured. However, since the blood coming from it is accumulating between the dura matter and the skull, which are rigid structures, the hematoma takes time to form.
The period between when the patient regain conciousness and when hematoma become big enough to cause symptoms is called the Lucid interval.

Patient may present with many abnormalities prior to 2nd loss of conciousness due to the hematoma, such as oculomotor nerve palsy. It depends on where the hematoma form.

Compare with subdural hematoma which is due to rupture of the bridging veins. Try to explain why no lucid interval in subdural hematoma.

Summary: Lucid interval happen in epidural hemorrhage because although blood is from a high pressure vessel(an artery), it accumulates in a tight space, thus takes time to accumulate enough to cause symptoms.

If you have any other explaination which you know off, read somewhere etc, please let me know ok. :)

5 referrals:

~Wong~ said...

alamak, hav to find own answer ah? k la.. will do so when I'm free..

Jeff said...

regarding ur question in my blog, u have to ask dr milton lum who wrote the article haha

but in my opinion la....the stupid guy is actually choking his penis. Both arterial and venous blood will be reduced, some sort of "penile torsion".....sure ischaemia if long enough kua...however, since the muscle there is not in "active" state(hopefully,so maybe did not require as much blood as testis(which is active in producing tadpoles)and other part of the body active tissue.. so "torsion" occur less rapidly...

armouris said...

more info on epidural haematoma here - Epidural Haematoma - A Blow to the Head

Anonymous said...

a lucid interval can also occur in a subdural hematoma.

Jub varghese said...

Initial unconsciousness is thought to be due to the concussive effect of the blow to the head. The lucid period is the time required for the clot to grow to proportions great enough to produce compression of the brain.