Head injuries are common in motorcycle accidents.
A subdural hematoma usually results from a minor or perhaps major head injury that happens in a motorcycle accident, fall, sports injury or an altercation. The symptoms of a subdural hematoma vary, depending on the size and location of the hematoma, as well as on the type of subdural hematoma.
What is a Subdural Hematoma?
A subdural hematoma is also called a subdural hemorrhage. It is almost always associated with a traumatic brain injury. Blood comes out of veins within the outermost meningeal layer, which can also be described as occurring between the dura and the arachnoid mater, which cover the brain.
Bridging veins on the surface of the brain are responsible for the bleeding in a subdural hematoma. The hematomas have a chance to get big and increase the intracranial pressure inside the brain. If the pressure gets too large, there can be brain damage and a chance of a herniation of the brain, which can be deadly. Subdural hematomas can be differentiated from epidural hematomas, which involve bleeding from tears in the arteries between the dura and the skull. Epidural hematomas are more dangerous than subdural hematomas.
Subdural hematomas are divided into three types:
• Acute subdural hematoma—this is the type of hematoma often seen after major trauma, such as that found in a motor vehicle accident. It is the most dangerous of all types of subdural hematoma and can have a high rate of mortality if not treated quickly with surgery. The hematomas tend to be large and can be associated with cerebral contusions. Acute subdural hematomas have a higher mortality rate than epidural bleeds because the forces of the acceleration and deceleration cause severe brain damage along with the subdural hematoma. Unfortunately, the mortality rate is between 60 and 80 percent with this type of hematoma.
• Subacute subdural hematoma—this involves venous bleed that has a slower onset of symptoms than acute subdural hematomas. They usually develop over a period of hours to a day after the injury. They have a better prognosis than acute subdural hematomas. They often still need surgical correction to make them go away.
• Chronic subdural hematomas take days to weeks to develop. They often follow minor head trauma and can have no appreciable cause in around half of cases. Some can take months or even years to be discovered. The bleeding can be gradual and slow or can be from multiple minor bleeding episodes. The bleeding usually stops on its own. If the chronic subdural hematoma is less than 1 cm in depth, only 22 percent of patients have less than a good or complete chance of recovery. Chronic subdural hemorrhages are commonly seen in older persons who suffer minor head injuries and develop bleeding in the brain.
Symptoms of Subdural Hematoma
The symptoms of a subdural hematoma generally come on slower than with an epidural hematoma because the bleeding comes from lower pressure veins rather than higher pressure arteries. Symptoms and signs of a subdural hematoma can occur right away or it can take up to two weeks to show anything. If a subdural hematoma involves a large bleed, there can be increased intracranial pressure, which can cause brain damage.
Other symptoms and signs of a subdural bleed include:
• History of a recent injury to the head
• Headache pain
• Numbness of various body areas, depending on the location of the bleeding
• Pain in the neck
• Being disoriented
• Having amnesia for the event or things surrounding the event
• Loss of appetite
• Changes in personality
• Ataxia—difficulty in walking
• Slurred speech or other difficulty in speaking
• Changes in breathing, such as Cheyne-Stokes breathing
• Hearing loss
• Ringing in the ears—tinnitus
• Blurry vision
• Abnormal eye movements or having a deviated gaze
Any change in thinking or mentation along with sensory or motor deficits should arouse the suspicion for subdural hematoma, especially in face of having suffered some kind of head trauma.
A subdural hematoma is generally caused by a head injury in which there has been a rapid change in velocity of the veins within the skull, which then bleed. This can happen in a motor vehicle accident, motorcycle accident, in a fall from a great height (in young people), or a simple fall from the same height in older people. It can result from an altercation or sporting injury as well. Motor vehicle and motorcycle accidents have perhaps the highest rate of subdural hematomas.
Subdural hematomas are considerably more common than epidural hematomas. Subdurals come from shear forces such as those seen in shaken baby syndrome. Similar shearing forces result in pre-retinal hemorrhages and in intra-retinal hemorrhages. Subdural hemorrhages can be seen in alcoholics and in the elderly who have brains that are shrunken when compared to the skull. This cerebral atrophy stretches out the bridging veins between the layers of the meninges so they are more likely to break. The elderly are also more commonly on aspirin and warfarin—both anticoagulants that thin the blood. If one is on these types of medicines, even a small or minor head trauma can cause a subdural hematoma.
Another cause of a subdural hematoma involves having a reduction in cerebrospinal fluid pressure in the elderly. This causes a lower than normal pressure in the subarachnoid space. It pulls the arachnoid layer away from the dura mater so the rupture of the intervening blood vessels is more likely.
Risk Factors for Subdural Hematoma
Risk factors for getting a subdural hematoma include being of a very young or a very old age. When the brain shrinks in older age, the subdural space gets larger and the veins that cross over that space must travel a larger distance. These veins are more vulnerable to becoming torn. Veins in the elderly are also more brittle; this makes them chronically predisposed to breaking, even with a minor injury.
Infants also have bigger subdural spaces, making them more prone to breakage of the veins. This is why subdural hematomas happen to a greater degree than other brain injuries when a child has shaken baby syndrome. In juveniles without much trauma, a subdural hemorrhage can happen if the child has a subarachnoid cyst.
Other reasons why subdural hematomas might be more likely include those on anticoagulant therapy, long term alcoholics and people with dementia.
Diagnosis of a Subdural Hemorrhage
Prior to the era of CT scanning, it was extremely difficult to diagnose any type of brain hemorrhage. Certainly a cerebral angiogram could be done to see the vasculature of the brain but this is a painful examination that takes more time to do than the standard CT scan.
The CT scan without contrast is the best test for subdural hemorrhage, although it may not be able to assess whether the hemorrhage is epidural or subdural. It can show areas of brain trauma as well as the presence of coup and contrecoup injuries. Blood shows up bright white on CT scan and any fractures of the skull can also be identified. The CT scan can tell if the bleeding is fresh bleeding or if the subdural hemorrhage is chronic and has been there for many months.
Plain films of the head will show areas of fracture which might be suspicious for subdural hematoma but it will not show any actual areas of bleeding. In almost all cases, it is better to turn to the CT scanner before considering any plain films.
Treatment of Subdural Hemorrhage
Before treating a subdural hemorrhage, a full medical and neurological assessment should be done along with a CT scan or MRI exam that will detect the presence of a subdural hematoma.
The treatment of a subdural hematoma depends on how big it is along with how fast it is growing. Subdural hematomas that are small and not growing can be treated by watchful waiting. In such cases, the body will most likely heal itself and the hematoma will dissolve or become fibrotic.
If a small hematoma is growing with the potential to grow larger, it can be treated by drilling a small hole in the part of the skull overlying the hematoma. A small catheter is inserted into the hole and the hematoma is evacuated. This is a procedure that can be done right at the bedside with little anesthesia and sterile hand tools.
Large, growing, or extremely symptomatic hematomas need to be treated by doing a craniotomy and actually opening the skull. The surgeon exposes the dura and opens it. The blood clot is irrigated or sucked out of the wounded area and the various sites of bleeding are controlled. Possible postoperative complications of a craniotomy for subdural hematoma include having increased intracranial pressure, edema on the brain, new bleeding areas or areas of recurrent bleeding, meningitis or encephalitis, and seizure activity. Any injured blood vessels need to be repaired in order to prevent stroke.
If the patient is unstable, has a large hematoma, is old or deteriorating, quicker action than a craniotomy is necessary. In such cases, the patient needs to have burr holes placed in the skull overlying the hematoma with suction or simple drainage. This can be used as a form of palliative management in a situation where the patient is old and infirm, or is a patient that has no real hope for recovery.
Complications of a Subdural Hematoma
Large subdural hematomas can cause increased intracranial pressure that causes brain herniation through the foramen magnum and death. On the other hand, people with a small subdural hematoma can heal spontaneously with no neurological sequelae. Most people fall somewhere in between. Possible complications following a subdural hematoma can come from the hematoma itself, damage to nearby brain tissue, or to the treatment of the hematoma. Such complications include:
• Seizures or epilepsy
• Long term memory problems
• Problems with concentration
• Longstanding dizziness
• Persistent anxiety
• Chronic headaches
• Numbness or weakness of a body part
• Speech deficits
• Cognitive deficits
• Problems with attention
• Poor balance or coordination
• Personality Changes
• Difficulty swallowing
• Visual changes
Some of these complications can be managed with medication or physical therapy while others cannot be treated.
I’m Ed Smith of AutoAccident.com (Law Offices of Edward A. Smith) and a motorcycle injury lawyer with decades of experience in traumatic injury claims. I can be reached at (916) 921-6400, or (800) 404-5400.