Brain hemorrhage is also called Intracranial bleeding
PKGhatak, MD
This diagram is an exaggerated view of 3 covers of the brain called meninges.
If you can strip the scalp that covers the head, you see a bony box, the cranium or skull. A skull is made up of several bones, appears more like plates, joined together by narrow wave like suture lines or joints. Though called joints, these suture lines are tightly fitted with virtually no space in between. The bones also behave differently because skull bones have no periosteum which supplies new bone for fracture healing. A skull fracture may take 6 months to heal or may not heal at all. But fibrous tissues grow around the fractures hold the bone pieces together.
Epidural bleeding.
Moving further towards the brain the first layer of the brain covering is a tough membrane, like parchment paper, called Dura Mater. There is only a virtual space between the bone and dura mater known as Epidural space. Three pairs of arteries, one on each side from each pair nourish the dura mater. The middle one, the middle meningeal artery, is the dominant one. It runs along grooves inside of the bone. Fracture of bone also tears the artery. Blood sprats out from the artery in the epidural space and strip away dura mater from the bone. With each heartbeat, more blood accumulates. And bleeding will not stop until the artery is clamped.
Blood pushes soft brain tissues to the other side and finally pushes the brain downwards. At this point, without medical intervention, death is imminent.
Subdural bleeding.
Move further toward the brain from the dura mater. The second layer of the brain cover is the Arachnoid membrane.
Arachnoid means spider like. The arachnoid membrane has many long, loose fibers resembling spider legs. The virtual space between the dura mater and arachnoid membrane is known as Subdural space. Bleeding in this space is called Subdual bleeding or subdural hematoma. Many tiny veins traverse subdural space. Veins are thin-walled and subjected to easy rupture.
In old age the brain tissues shrink and move away from the bone, making the vein unsupported and liable to break with sudden shaking of the head or head moving back and forth after a sudden stop of an automobile or after a fall. Because bleeding from veins is slow and the accumulated blood inside the head increases the pressure that may be enough to stop venous bleeding. But that is only the first part.
The patient may not complain much initially or have some headaches. But after 3- 4 weeks, family members will notice the patient is having difficulty in walking, weakness of legs, or urinary incontinence. These new symptoms are due to the clotted blood drawing cerebrospinal fluid and enlarging. Early evacuation of clots is called for before neurological damage becomes permanent.
Subarachnoid bleeding.
Below the arachnoid membrane is the final covering of the brain called Pia Mater.
Pia means delicate, The word is derived from the Italian word mother. This layer is very vascular and is intimately attached to the brain tissue. If you again look at the diagram you will see medium sized blood vessels are going in and out of this Pia matter.
There are 2 pairs of arteries that bring blood to the brain, one pair from the sides and one pair from the back. The internal carotid artery, one on each side, enters the brain through a small opening of the skull. After entering the skull, it pierces the dura mater and arachnoid membrane and gives branches and then continues as the main artery of the brain called the Middle cerebral artery. Most of the subarachnoid bleeding occurs from one spot or another from the junction where the middle cerebral artery gives off branches. All these branches lie on the surface of the pia mater, underneath the arachnoid membrane.
Like epidural bleeding, subarachnoid bleeding is from a break in the arterial wall. And so blood is spurting out with each heartbeat and bleeding will not stop until the bleeding artery is clamped.
A special characteristic of subarachnoid bleeding is that the blood initially leaks only a small amount producing excruciating pain and if the patient arrives in ER in time, then a proper diagnosis and treatment can be initiated before the actual rupture of the arterial wall happens.
Unlike the previous two bleedings discussed above, subarachnoid bleeding is not just from one cause. A very brief discussion is presented here.
Common causes of subarachnoid bleeding.
By convention, subarachnoid bleeding is categorized into two groups- A. trauma and B. spontaneous bleeding.
A. Trauma.
When injury to the head produces damage to the brain tissues, the injury tears all three layers of meninges, and not only the arachnoid membrane. These types of injuries are very serious and properly treated only in trauma centers.
B. Spontaneous arachnoid bleeding.
Spontaneous subarachnoid bleeding is of two categories.
1. Hereditary or gene mutation, 2. Acquired condition leading to bleeding.
1. Hereditary.
People are born with abnormal connective tissue that makes blood vessels wall liable to fray easily. However, not all the members are equally affected, those who have high BP develop bleeding. Some of the hereditary conditions are fibromuscular dysplasia, Marfan syndrome, Ehlers Danlos syndrome, and polycystic disease of the kidney. A few of them will be presented here.
A. Berry aneurysm, also known as Saccular aneurysm.
A tiny bubble like outpouching develops at the junction of a branch from the main artery. The tiny aneurysm has a narrow neck. When one is present, more aneurysms may turn up later. If detected in time the aneurysmal sac can be sealed off by injecting endovascular coiling via a catheter threaded through the femoral artery into the sac of the aneurysm. The blood inside the aneurysm will clot around the coil and seal off the aneurysm.
B. Fusiform Aneurysm.
The fusiform aneurysm is less common, these aneurysms have no neck, unlike berry aneurysms. Also, structurally these are not outpouching but the weakness of the middle layer of the artery at certain points, which bulges out. The resultant aneurysms have a wide channel communicating with the artery and the outer covering is made up of thin adventitia. Coil embolization is not suitable, instead, a supporting wall structure called Pipeline Embolization Device (PED) is placed at the site by a catheter introduced via the femoral artery. PED provides the scaffolding upon which endothelium grows and repairs the weakness permanently. After placement of PED blood is prevented from entering the aneurysm and it shrinks and disappears.
C. Arteriovenous malformation (A-V malformation)
The malformed blood vessels are not strong enough to withstand high BP and are liable to rupture. Intracranial A-V malformation is usually seen in people who also have A-V malformation of the face and neck area.
2. Acquired causes.
a. In today's world, Cocaine and Amphetamine addiction are the primary cause of spontaneous cerebral bleeding. Sickle cell anemia can obstruct arteries during a sickle cell crisis. Obstruction of blood flow weakens the arterial wall and causes bleeding.
b. Mycotic aneurysm.
Infection of the cerebral arterial may happen if the infected emboli from heart valves are carried to the brain and lodged in arteries. The organisms likely to produce such emboli are Staph and Streptococci, Bacteroides, Clostridia, and fungi – Aspergilla and Mucormycosis from nasal sinuses infection.
c. Vasculitis.
Vasculitis/arteritis also happens from noninfectious causes. Noninfectious vasculitis consists of many varieties and has various pathogenesis. Subarachnoid bleeding is only a possibility and is not common in every type of vasculitis. Those that may produce bleeding will be mentioned.
1. Giant Cell Arteritis. (GCA).
The other name of GCE is temporal arteritis. It is an immunological disorder of uncertain etiology. The hallmark of GCE is granuloma formation with Giant cells. The new blood vessels that grow in the granuloma may bleed and can cause subarachnoid hemorrhage,
2. Polyarteritis Nodosa.
Polyarteritis nodosa is characterized by the presence of localized inflammatory nodules in multiple systems, most easily detected on the skin of the lower legs; usual lesions are in the kidneys and respiratory tract. Though nervous systems are affected but are mostly in the peripheral nervous system and very rarely produce cerebral bleeding.
3. Recently, cerebral amyloid angiopathy is added to the list as an unusual and infrequent cause of cerebral infarction or intracerebral hemorrhage due to cerebral amyloid angiopathy.
Other systemic causes.
Many other conditions produce spontaneous subarachnoid bleeding. The following are a few examples.
a. Low platelet count from Dengue, Covid-19, and many other viral infections.
b. Platelet antibodies from autoimmune diseases and Intravascular coagulation use up platelets and may bleed in addition to blood clots. Antiplatelet drugs use is a risk factor
c. Anticoagulant medications use for medical reasons, including aspirin and cox inhibitors.
d. Leukemias. Chemotherapy, radiation therapy, and brain cancers.
D. Strokes.
Hemorrhagic stroke.
Cerebral blood vessels, like coronary arteries, undergo plaque formation and rupture, producing hemorrhagic strokes. Fortunately, the incidence is falling from the wide knowledge gained from the press and social media.
Hypertension, diabetes, high cholesterol, obesity, cigarette smoking, sedimentary lifestyle and hereditary are risk factors for hemorrhagic stroke.
Ischemic stroke is more common among all causes of stroke.
The diagnosis and treatment of subarachnoid bleeding have advanced greatly by the use of intracranial Doppler ultrasonography, subtraction angiography and MRI. Interventional radiologists have taken over the delicate operation of catheter placement inside the tiny blood bubbles and injecting coils or pipeline devices.
Intravenous Labetalol and Nifedipine are very useful drugs to lower high BP rapidly and safely. Prevention of pressure buildup inside the head following intracranial bleeding is treated by timely placing a drain in the ventricular cavity. Various monitoring devices and sharing patients' care with specially trained nurses have greatly improved the outcome of this potentially fatal disease.
*****************************************************
