| To understand epidural and subdural hematomas | | | | arrived at an emergency department in coma, |
| -- two serious consequences of head injuries | | | | but they can also be seen in conscious |
| -- we need to know the basic anatomy of the | | | | patients. Epidural hematomas usually occur in |
| brain and its coverings. Imagine an evil | | | | conjunction with skull fractures, and this is |
| carpenter with an electric drill intent on | | | | no coincidence, as the ruptured blood vessel |
| drilling into a person's brain. What layers | | | | often lies beneath the fracture. The presence |
| would the drill encounter in its passage from | | | | of an epidural hematoma signifies a highly |
| the outside of the head to its | | | | dangerous condition. Between 5 and 43% of |
| destination?The drill would pass through the | | | | people who have them die. Emergency surgery |
| skin and then the skull (braincase) before | | | | to remove the clot is the usual |
| penetrating a series of three membranes | | | | treatment.When considering subdural |
| comprising the meninges. In sequence, the | | | | hematomas, it is useful to divide them into |
| three membranes are the dura mater (Latin for | | | | acute and chronic varieties, with "acute" |
| "tough mother"), the arachnoid mater | | | | meaning the hematoma is new, and "chronic" |
| (cobwebby mother) and the pia mater (tender | | | | meaning it has been present for at least |
| mother) and then finally the brain | | | | three weeks. (The hematoma can also pass |
| itself.Epidural and subdural hematomas are | | | | through a "subacute" phase, meaning that it |
| alike in that they are masses of clotted | | | | has been present for 3 days to 3 weeks.) By |
| blood (hematomas) caused by head trauma and | | | | the time an acute subdural hematoma has |
| deposited outside the brain but inside the | | | | become chronic, it is a thick liquid instead |
| skull. However, they differ in their | | | | of a solid blood clot, and also appears |
| locations relative to the dura mater. An | | | | darker on CT scans.Acute subdural hematomas |
| epidural hematoma lies outside (on top of) | | | | usually occur in people with obvious and |
| the dura mater, while a subdural hematoma | | | | significant blows to the head. In one study |
| lies inside (beneath) the dura mater and | | | | they were present in 24% of the patients who |
| outside the arachnoid mater. Thus, the | | | | arrived at an emergency department in coma, |
| locations of the two kinds of hematoma are | | | | but can be present in non-comatose patients |
| encoded in their names -- "epi" is Greek for | | | | as well. Acute subdural hematomas are |
| "upon" and "sub" is Latin for "below." A | | | | associated with a death rate between 30 and |
| third kind of hematoma caused by head | | | | 90%, with a figure of 60% typically cited. |
| injuries is traumatic intracerebral | | | | Emergency surgery is the usual treatment, |
| hemorrhage. These occur within the brain | | | | though studies have shown that alert patients |
| tissue itself and are no less serious than | | | | with small subdural hematomas can do as well |
| those outside the brain, but are not the | | | | without surgery if monitored closely for |
| subject of the current essay.Epidural and | | | | signs of worsening.Infants are also |
| subdural hematomas are produced by ruptures | | | | vulnerable to acute subdural hematomas. |
| of different blood vessels. Epidural | | | | Neurosurgeons at the Kaohsiung Medical |
| hematomas are usually caused by bleeding from | | | | University in Taiwan reviewed records on 21 |
| an artery that nourishes the meninges known | | | | children, ages 6 days to 12 months, who had |
| as the middle meningeal artery, while | | | | acute subdural hematomas. In this case |
| subdural hematomas are usually due to | | | | series, "shaken baby syndrome" was the most |
| bleeding from veins that drain blood away | | | | common cause. Eight of the infants underwent |
| from the surface of the brain.Yet another | | | | an immediate operation, and another 11 |
| difference between epidural and subdural | | | | required delayed surgery. While most of the |
| hematomas is what they look like on computed | | | | children did well, one baby died and another |
| tomographic (CT) scans. When the bleeding was | | | | 7 sustained moderate to severe disabilities |
| recent, both show up as intensely bright | | | | from their injuries.Chronic subdural |
| objects on the scan, but the shapes of the | | | | hematomas often show up in patients over 60 |
| blood clots are different. In epidural | | | | years of age in whom the head injuries that |
| hematomas the blood is more limited in its | | | | caused them might have seemed trivial when |
| spread because it has to push harder to move | | | | they occurred, or might even have been |
| outward in the tight space between the inner | | | | forgotten. Older people are especially |
| surface of the skull and the outer surface of | | | | vulnerable due to the fact that their brains |
| the dura mater. In contrast, the bleeding | | | | have atrophied (shrunk) and the veins |
| that produces subdural hematomas is more free | | | | draining the surface of the brain are |
| to spread in the looser space beneath the | | | | stretched and fragile, easily disrupted by |
| dura mater and typically runs from the front | | | | glancing blows. Risk of subdural hematoma |
| of the head to the rear.One issue that | | | | rises still higher if the individual falls a |
| applies to both kinds of hematomas is that | | | | lot, drinks alcohol a lot or takes |
| they occupy space -- sometimes a lot of it -- | | | | blood-thinning medication.Subdural hematomas |
| within the braincase where there isn't a lot | | | | can expand progressively to the point of |
| of extra space to go around. As they expand | | | | causing symptoms like headache, slurred |
| they compress the brain tissue next to them | | | | speech, confusion, lethargy, unsteadiness or |
| and additionally raise the pressure within | | | | even a seizure. Surgery to remove the |
| the skull which can damage the rest of the | | | | hematoma and stop the bleeding is the typical |
| brain. Moreover, the hematoma is not | | | | treatment, and 93 to 97% of patients survive |
| necessarily the only problem caused by the | | | | to 30 days after surgery. Most regain their |
| head injury. The blow to the head that caused | | | | pre-injury level of function. Milder cases of |
| the bleed can also damage the brain tissue | | | | chronic subdural hematoma can be monitored |
| directly.Who gets epidural hematomas? They | | | | without surgery.(C) 2006 by Gary |
| usually occur in people with obvious and | | | | CordingleyGary Cordingley, MD, PhD, is a |
| significant blows to the head, as from motor | | | | clinical neurologist, teacher and researcher |
| vehicle accidents. In one study they were | | | | who works in Athens, Ohio. |
| present in 10% of head-injured patients who | | | | |