Common Problems ( arranged alphabetically)
1. Arterio Venous Malformation (AVM)
Arteriovenous malformations (AVMs) are faults in the blood vessels that are believed to be formed during fetal development i.e. before birth. In this condition the normal blood circulation in the body is disrupted due to the abnormal network between the arteries and veins, resulting in diversion of the blood from the capillaries that supply blood to the organs. An AVM can occur anywhere on the body; however those in the brain or spine especially can have widespread effects on the body.
An AVM in the brain may not show any symptoms. It can cause
Over time brain AVMs can incur damage to the brain tissue due to inadequate blood supply, the effects of which slowly build up leading to symptoms in early adulthood.
There is no particular cause of a brain AVM but research has revealed that most brain AVMs develop during fetal development. In a normal body, the heart supplies oxygen-rich blood to your brain through arteries. The blood flow in the arteries gets slowed down by passing through a series of smaller network of blood vessels and finally ending with the smallest blood vessels known as capillaries. The capillaries slowly provide oxygen rich blood to the brain tissue. After providing the tissue with the required nutrients and oxygen, the blood then passes into small blood vessels and then into larger veins thereby taking the blood back from the brain to the heart to get more oxygen.
In an AVM, the arteries and veins lack this supporting network of smaller blood vessels and capillaries. Instead, the blood flows quickly and directly from the arteries to veins, bypassing the surrounding tissues.
A brain AVMs can be diagnosed with the following tests:
1. Computerized tomography (CT) scans
A CT scan is an imaging technique that is particularly useful as a quick initial diagnostic tool for brain hemorrhage.
2. Cerebral angiography (DSA)
Cerebral angiography is the most specific test that reveals the location and characteristics of the blood vessel pattern, which is important while planning treatment.
3. Magnetic resonance imaging (MRI)
MRI through the use of powerful magnets and radio waves creates images of your brain. A MRI is finer than a CT scan that can show more detailed changes in brain tissue associated with an AVM. It provides information regarding the exact location of the AVM and any associated bleeding in that area.
Treatment For AVM
The treatment of AVM depends on the symptoms, the type of AVM and its size and location.
Even if there are no symptoms, a person with an AVM should keep away from activities that will increase blood pressure and avoid blood thinners like warfarin. He should get regular checkups done with a neurologist or neurosurgeon.
If an AVM has led to brain hemorrhage and/or is in an area of the brain that can be easily operated, then surgery may be recommended.
In this procedure, the surgeon inserts a catheter (a long thin tube) into a leg artery and guides it through blood vessels to your brain using X-ray imaging or fluoroscopy. Here the arteries of the AVM can be blocked by using liquid tissue adhesives, micro coils, particles and other materials. A less invasive procedure than traditional surgery, endovascular embolization may be performed alone or is commonly used prior to other surgical treatments. This makes the procedure safer by decreasing the size of AVM or the chances of bleeding.
If an AVM is located in an area that is difficult to operate by regular surgery, then it may be treated with stereotactic radiosurgery. Firstly, a cerebral angiogram is done to locate the AVM, and then focused high energy beam is concentrated on the brain AVM to cause direct damage to the vessels. This will produce a scar and allow the AVM to thrombose.
Large Cerebral Arterio Venous Malformation (AVM)
This 23 years old college going student presented with repeated episodes of convulsions. The MRI scan of the brain raised a suspicion of an AVM. There was no brain haemorrhage. The cerebral angiography showed a large AVM. This was embolised by my neuroradiologist colleague. The residual AVM was later excised completely by microsurgical techniques. The patient made uneventful recovery without any neurological recovery. However, his anticonvulsant medicines continued.
2. Brain Aneurysms
A weak or fine spot on a blood vessel in the brain that balloons out and fills with blood is called as a cerebral aneurysm.It can leak or rupture, spilling blood into the neighbouring tissue (commonly known as subarachnoid haemorrhage or SAH). Few cerebral aneurysms don’t bleed or cause other issues, especially those that are very tiny. These are incidentally detected in the course of investigation done for some other reason. Cerebral aneurysm can occur anywhere in the brain, but majority are located along a loop of arteries running between the underside of the brain and skull base (Circle of Willis).
Aneurysms may be a result of an abnormality in an artery wall that is congenital. Cerebral aneurysm is observed more commonly in people having particular genetic diseases, like connective tissue disorders and polycystic kidney disease, and specific circulatory disorders such as AVM i.e. arteriovenous malformations ( knotted tangles of veins and arteries in the brain that disrupt the flow of blood). Other causes can be trauma or head injury, high BP, infection, tumours, atherosclerosis and other diseases of the vascular system.
Types Of Aneurysms
Cerebral aneurysm is of 3 types.
1. Berry aneurysm, a rounded or pouch-like sac of blood attached by a neck or stem to an artery or a branch of a blood vessel is called a saccular aneurysm. It is the most commonly occurring form of cerebral aneurysm and is usually found on arteries at the base of the brain. It usually occurs in adults.
2.A lateral aneurysm is seen as a protuberance on one wall of the blood vessel,
3.Fusiform aneurysm is formed by the broadening along the blood vessel walls.
Size is also a used to classify aneurysms. Small aneurysms are not more than 10 mm in diameter (around the size of a large pencil eraser), larger aneurysm are around 11-25 mm (about a coin’s width), and giant aneurysms are greater than 25 mm in diameter.
Brain aneurysms can happen to anyone and at any age. It is observed more commonly in adults than in children and its frequency is slightly more in women than in men. Higher risk is present in people with certain inherited disorders.
WHAT ARE THE DANGERS?
Haemorrhagic stroke, permanent brain damage and other serious complication or even death can be caused due to aneurysm that may burst and bleed into the brain. After bursting once, the aneurysm can even burst again. The re-rupture is typically devastating and can be life threatening.
More grave post rupture complication of brain haemorrhage is vasospasm. In vasospasm, other blood vessels in the brain contract and restrict the flow of blood to essential areas of the brain. This decreased flow of blood can cause stroke or further tissue damage.
Hydrocephalus is another serious complication of subarachnoid haemorrhage. In this condition, excessive accretion of cerebrospinal fluid in the skull widens fluid pathways called ventricles that can bloat and exert pressure on the brain tissue.
Symptoms Of Cerebral Aneurysms
Symptoms are absent in most cerebral aneurysms until they either become large or burst. Aneurysms that are small and unchanging generally won’t produce symptoms. On the other hand a larger aneurysm growing steadily may exert pressure on tissues and nerves. The symptoms are pain above the eye as well as behind it, weakness, numbness, or paralysis on a single side of the face; dilation of pupils and changes in vision. When there is haemorrhage of an aneurysm, the person may experience an expected and extremely severe headache, vision problems, nausea, stiff neck and / or loss of consciousness. The headache is especially excruciating and is usually different in degree and intensity from other headaches. Sometimes an aneurysm leaks for days to weeks before it ruptures. During this period, “Sentinel” or warning headaches may be felt. Only a few people have sentinel headache before an aneurysm rupture.
Some other signs that a cerebral aneurysm has burst are nausea and vomiting along with severe headache, drooping eyelid, increased sensitivity to light, and confusion. Some people may experience seizures too. When people experience these symptoms or along with a combination of other symptoms, they should seek medical attention immediately.
Diagnosis Of Cerebral Aneurysms
Majority of cerebral aneurysms go undiscovered until they rupture or are detected by brain imaging which may have been suggested for some other condition. Many diagnostic methods are available to guide and give information about the aneurysm and the best method of treatment. The tests are generally done following a subarachnoid haemorrhage, for confirmation of the diagnosis of an aneurysm.Computed tomography (CT) of the head is a quick, pain free, non-invasive diagnostic tool that can reveal if a cerebral aneurysm is present and find out, for those aneurysms that have a burst, if there is blood leak into the brain.
Angiography is a dye test that is used to examine the arteries or veins. It is a significant diagnostic test in brain stroke management and accurately determines the shape size, location of the aneurysm, or the blood vessel that has bled.
MRI i.e. magnetic resonance imaging produces detailed images of the brain by using computer-generated radio waves and strong magnetic field. Images of blood vessel is produced using MRA (Magnetic resonance angiography). The images may be viewed as either 3 – dimensional pictures or 2 – dimensional cross slices of the brain and vessels. These pain free non-invasive procedures can help in understanding the size and shape of an aneurysm and to detect bleeding in the brain.
Treatment Of Cerebral Aneurysms
These are few surgical options available for the treatment of cerebral aneurysms –
i) Microvascular clipping is a procedure in which the blood flow to the aneurysm is cut. Once anaesthesia is administered, a portion of the skull is removed and the aneurysm is located. Using a microscope, the blood vessel that feeds the aneurysm is isolated and a small, metal, clothespin-like clip is placed on the aneurysm’s neck, cutting off its blood supply. The clip stays in the person preventing the risk of future bleeding. After replacing the piece of skull, the scalp is closed. It is found that clipping is highly effective, depending on the aneurysm’s location, shape and size.
ii)Endovascular embolization is a substitute for surgery. Once the patient is under anaesthesia, the physician inserts a catheter (long thin plastic tube) into an artery (generally in the groin) and threads it, using angiography, through the body to the aneurysm site. Detachable coils are passed through the catheter using a guide wire and released into the aneurysm. The aneurysm is filled with coils, blocking its blood circulation and causing blood to clot which in turn destroys the aneurysm.
iii) Other treatments for a cerebral aneurysms are to control the symptoms and can involve anticonvulsants for preventing seizures and analgesics for treating headaches. It is possible to treat vasospasm using calcium channel-blocking drugs. Also, if the person is restless, sedatives may be administered. A shunt can be inserted surgically into a ventricle many months after the rupture if the cerebrospinal fluid buildup is causing harmful pressure on surrounding tissue. People who have experienced a subarachnoid hemorrhage usually require speech, rehabilitative and occupational therapy to regain lost ability and learn to cope with any disability that is permanent.
This 54-year-old gentleman presented with a brain hemorrhage. The cerebral angiography showed a large aneurysm of the middle cerebral artery. The aneurysm was clipped successfully. He made an uneventful recovery. We occasionally use endoscopes during these surgical procedures to confirm complete occlusion of the aneurysm and to exclude occlusion of any other blood vessel.