The brain and spinal cord are protected from environmental influences not only by the bone structures that surround them (skull and spine, respectively), but also by the membranes. In total, there are three shells between which there are cavities, or spaces. Read more about these structures later in the article.
Brain shells
In order to understand how the spaces between the membranes of the brain are arranged, including the subdural space, one should know what shells generally surround the brain tissue.
If you follow from the outside inward, you can distinguish the following meninges:
Moreover, they are identical for both the brain and the spinal cord. Shells in the spinal cord, in fact, are a continuation of the head.
The hard shell is the outermost. It in the form of a bag covers all brain structures, but does not fit snugly to the bones of the skull and vertebra. Between it and bone structures is still the periosteum.
The arachnoid is in the middle. She looks like a thin sheet that is not saturated with vessels. Many bars run from it to the hard shell, penetrating the entire space between these two structures.
The soft membrane is directly adjacent to the brain or spinal cord. It consists of two leaves, between which there is a large number of vascular elements. Around these vessels are the lymph spaces in which lymph circulates.
Epidural space
An epidural space is located between the dura mater and bone structures. It is filled with adipose tissue and vascular plexuses. At the level of transition of the spinal cord into the brainstem, the dura mater fuses with a large opening of the occipital bone, and the epidural space of the spinal cord passes into the same, only around the large brain.
Subdural space
If the epidural cavity is located above the hard shell of the brain, then the subdural cavity is located under it. Thus, the subdural space is located between the dura mater and the arachnoid. It looks like a narrow gap filled with a small amount of cerebrospinal fluid (cerebrospinal fluid).
Subdural hematomas
The accumulation of blood in the subdural space is called subdural hematomas. The main reason is a head injury. Moreover, the accumulation of blood between the membranes of the brain is much more common than in the spinal cord.
A hematoma in the subdural space can occur at any age. According to statistics, such incidents most often lead to its development:
- accidental trauma in childhood;
- youth traffic accidents;
- falling from their height in the elderly.
With head injuries in 15% of cases, blood accumulation develops in the subdural space of the brain. If it speaks of fatal head injuries, then a hematoma is present in 30% of cases.
Clinical picture
The accumulation of blood in the spaces between the membranes leads to an increase in pressure inside the cranium and compression of the brain tissue. The larger the hematoma, the more severe the clinical manifestations. Most patients have the following symptoms:
- impaired consciousness like a stupor, stupor or coma;
- pupil enlargement from the side of the lesion;
- violation of the pupil reflex;
- the presence of focal neurological symptoms (determined by a neurologist during a patient examination).
With extensive hematomas or untimely treatment for clinical help, edema and brain displacement increase. This leads to pinching of the medulla oblongata, in which there are important centers of respiration and heartbeat. As a result, cardiac arrest or respiratory arrest is possible.
But a hematoma can be not only in the brain. Perhaps the accumulation of blood in the subdural space of the spinal cord during its trauma. Often the cause is spinal fractures. In this case, the following clinical manifestations are possible:
- violation of sensitivity below the level of damage (hypesthesia) or its complete absence (anesthesia);
- weakness of the extremities (paresis) or complete immobility (paralysis);
- possible disruption of the pelvic organs (urinary retention or incontinence).
Diagnostic Methods
If you suspect the presence of an epidural hematoma, additional examination methods should be performed as soon as possible. Time plays a very large role here, especially when it comes to intracranial hematoma. In this case, hematomas are most often found in the middle cranial fossa and at the top in the frontoparietal site.
Typically, a computed tomography (CT) scan is sufficient to make a final diagnosis. This is an X-ray diagnostic method that allows you to accurately see the bone and shell structures of the brain, visualizes the vertebra, epidural and subdural spaces of the spinal cord. In addition, CT shows blood accumulation very well. Therefore, for the diagnosis of hematomas, this method has virtually no equal.
In the absence of CT, radiography of the skull or spine can be done. But, of course, the diagnostic value of this method is much lower.
Conclusion
The accumulation of blood in the subdural space is a serious problem that needs the most rapid diagnosis and surgical intervention. Since the spaces between the membranes of the brain are very narrow and supple, the blood that collects in them quickly leads to damage to the brain structures.
But it is important to remember that there are pathologies that can mimic the subdural hematoma. Therefore, they must be taken into account when making a diagnosis:
- an increase in the size of subdural spaces due to atrophy of the brain;
- subdural empyema - accumulation of pus between the hard and arachnoid membranes of the brain or spinal cord;
- epidural hematoma - the accumulation of blood between the hard membrane and periosteum;
- subdural hygroma - accumulation of fluid between the arachnoid and hard membranes.