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