Part two of a three part series
In our last post (part one) we introduced the subject of head injuries with an overview of trauma patterns typically found in head injury patients. Today let’s talk about bleeding inside the skull or intracranial hemorrhage.
Brain hemorrhage occurs when blood vessels inside the skull rupture. There are some non-traumatic causes as well. Ruptured aneurysms and hemorrhagic strokes would be a few examples of non-traumatic intracranial hemorrhages.
We classify bleeding in the skull by location, using the layers of the meninges as a guide. You may recall from EMT class that the meninges are fluid coated membranes that surround and protect the brain and spinal cord. They also encapsulate and limit the ways that blood can move inside the skull. How the brain bleeds is entirely dependant on which meningeal layers capture and contain the blood.
Do you remember those meningeal layers? Lets do a quick review in case you’ve forgotten, courtesy of our friends at ADAM education:
Each of these layers will contain and guide intracranial bleeding to some degree. Therefore, we classify these hemorrhages as epidural (above the dura mater), subdural (below the dura, within the arachnoid layer), subarachnoid (bleeding into the cerebrospinal fluid) and cerebral hemorrhage (AKA intraparenchymal bleeding.) Let’s explore each one of these in more detail:
Less than one percent of all intracranial hemorrhages are epidural in nature. Symptoms tend to develop rapidly and tend to be caused by laceration of the middle meningeal artery. Though bleeding from other regions can produce epidural bleeding, we suspect this bleeding pattern secondary to trauma in the temporal region of the skull. Epidural bleeds from venous sources will progress slower than arterial epidural bleeds.
Around half of the patients who experience epidural bleeding will have a brief loss of consciousness at the time of insult and then return to orientation and often report that they are asymptomatic. This temporary period of orientation is known as a lucid interval. The last two sentences were important. Go back and read them again. … No, seriously. The other half of patients will typically loose consciousness and never regain orientation. Even with appropriate care, 15 – 20% will die.
Lucid intervals in epidural bleeds can last from 2 minutes to 16 hours but usually fall in the 2 – 6 hour range. The dramatic nature of lucid intervals has caused the media to coin a more dramatic term for the process, “talk and die syndrome.” During the lucid interval, patients may initially have no symptoms and then develop a progression of headache, nausea, vomiting, lethargy, confusion, altered mentation and unconsciousness. Rapid intervention at a trauma facility is required.
Bleeding trapped between the dura mater and the brain proper forms a subdural hematoma. This tends to be caused by bleeding from the many veins that bridge the subdural space. This is most commonly caused by blunt head trauma. Therefore, subdural hematomas are frequently associated with skull fractures above and cerebral contusions below.
Acute – symptoms develop within twenty-four hours. 50% – 80% mortality rate.
Sub-acute – symptoms develop from two to ten days. 25% mortality rate.
Chronic – symptoms develop after around two weeks. 20% mortality rate.
The symptoms of subdural hematoma mirror the symptoms of epidural bleeding. The key difference is that the symptom progression is much more subtle due to the slower onset. It often takes a more experienced or alert clinician to trace the presenting symptoms back to the initial head injury.
The hematoma will ultimately need to be surgically evacuated.
This term refers to the phenomenon of bleeding into the cerebrospinal fluid (CSF). This results in bloody CSF and intense meningeal irritation. Patients with subarachnoid hemorrhage will have a sudden, severe headache that will begin localized and then spread into a more diffuse, dull, throbbing pain. Patients can also present with nausea, dizziness, severe neck pain, unequal pupils, confusion, seizures and unresponsiveness.
A collection of blood anywhere within the substance of the brain is termed a cerebral hemorrhage. The frontal and temporal lobes are particularly prone to this type of bleeding. They are most commonly a result of penetrating trauma but they can also be found with significant acceleration / deceleration types of forces which can tear vessels within the brain.
Symptoms are similar to other head injuries but vary greatly depending on the location and severity of the bleed. Onset is sometimes delayed, but once a constellation of symptoms evolves from a cerebral hemorrhage it usually progresses rapidly to unconsciousness.
Now you should have a good working knowledge of typical injury patterns and typical bleeding patterns in the brain. You know about mild, moderate and diffuse brain injuries, types of fractures and a whole variety of intracranial hemorrhages. Now you might be asking, “So what am I supposed to do about it, Steve?” Great question. We’ll get to that in part three. Until then, play safe.