Subdural Or Subarachnoid Hemorrhage

The dura and arachnoid are two of the three meninges present in humans. The meninges are the structures that surround the central nervous system. A subdural or subarachnoid hemorrhage refers to a hemorrhage that occurs below each of these two meninges.

the meninges

The brain and spinal cord are protected by the skull and spine, but they also have another protection system: the meninges, which are also involved in nervous development.

As the NIH Cancer Dictionary explains: “The meninges are the three layers of tissue that surround the brain and spinal cord.”   We have three of these layers that, from the outside to the inside, are:

• Dura mater.
• Arachnoid.
• Pia mater.

The outermost and thickest, the dura mater, separates from the bone through the epidural space. In the skull, this space is virtual, that is, it does not exist because the dura mater is attached to the bone. However, it exists in the spinal cord and is filled with veins and fat.

Below the dura mater is the arachnoid, separated by the subdural space. This space is also virtual and only becomes real when a hemorrhage occurs and the blood separates the two meninges.

The arachnoid sends to the pia mater a series of extensions that travel through the subarachnoid space. The subarachnoid space is occupied by the cerebrospinal fluid responsible, among other things, for dampening pressure changes due to sudden bumps or movements.

Finally, the pia mater is intimately attached to the nervous tissue, accompanying it even in its grooves. The possibility that it will also accompany you into the fabric is still under investigation.

Subdural or subarachnoid hemorrhage

In a subdural or subarachnoid hemorrhage, the first circumstance is the exit of blood from the blood vessels, which is stored in the spaces between the meninges. This causes damage to the brain tissue, thus generating several clinical conditions.

However, depending on whether the hemorrhage is subdural or subarachnoid, the triggers, the course of the pathology and its symptoms will be different.

Subdural hemorrhage

Subdural hemorrhage is defined as the storage of blood in the virtual space between the dura and the arachnoid. This blood is usually of venous origin and usually corresponds to traumatic causes. However, there are three types of subdural hematoma depending on how long it takes to become apparent:

• Acute.
• Sub-high.
• Chronic.

Acute subdural hematoma

That’s what becomes apparent most quickly. It is usually due to severe trauma that damages the veins that run from the cerebral cortex to the meninges.

Therefore, those who suffer from it usually immediately go into a coma. In addition, symptoms often appear when a specific part of the brain stops working. Some examples are:

• Hemiparesis: partial impotence for movement due to injury to the area that governs motricity.
• Mydriasis: anomalous enlargement of the pupil diameter due to damage to the area that controls the iris muscle.

Subacute subdural hematoma

It has a slower evolution and is usually less severe. This is due to the fact that the amount of blood released is less and the clotting mechanisms are able to stop the bleeding. Its cause is also often traumatic in nature.

First of all, consciousness is usually lost, which is later recovered. Afterwards, for several days, the person will experience progressive clouding, in addition to signs of focality.

Chronic subdural hematoma

It is a consequence of multiple minor traumas over time. These give rise to small releases of blood that, when not reabsorbed, end up causing a subdural hematoma of considerable dimensions. It is relatively frequent in the elderly.

The early symptom is usually headache or headache, associated with changes in affectivity and behavior. Deterioration is progressive, with a tendency to sleep, slowed thinking and other symptoms.

Subarachnoid hemorrhage

Subarachnoid hemorrhage is defined as the accumulation of blood between the arachnoid and the pia mater. Blood is usually of arterial origin and can correspond to several causes. The most frequent is the rupture of an aneurysm, but it can also be caused by vascular malformations.

Aneurysms may present with headaches or epileptic seizures before they rupture. In up to a third of cases, the triggering factor for aneurysm rupture is physical exertion with an emotional component or prolonged exposure to the sun.

Once they rupture, subarachnoid hemorrhage begins. For example, it  most often occurs in people who are between 40 and 60 years old. On the other hand, the onset of symptoms is sudden and there are:

• Vomiting.
• Clouding.
• Very intense headache.
• Photophobia (intolerance to light because of pain or discomfort).

Approximately 48 hours later, meningeal syndrome usually appears, caused by irritation of the meninges. Thus, to the above symptoms, there is a stiffness in the back of the neck. Focal deficits can also occur, such as paralysis of eye movements.

Subarachnoid hemorrhages cause sequelae in up to 60% of cases. In addition, 40% of survivors develop some form of addiction.