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