Veno-occlusive Diseases

Cerebral veno-occlusive diseases or stoke as a consequence can be defined as abnormal functions of the nervous system as a result of any pathology in the cerebral circulation. They are a disease group ranking 3rd, even 2nd according to some authors, among the fatal diseases, also they are the most common disease group that causes long-term disability.  Stroke or in other words cerebrovascular accident describes the event that usually leads to acute and focal neurological disorders due to any event affecting blood vessels in the brain or to the brain.  There are two main types of stroke: ischemic and hemorrhagic.  Ischemic stroke accounts for 80% of this disease.  Ischemic stroke occurs as a result of an obstruction within a blood vessel supplying blood to the brain and causes a shortage of oxygen and glucose thus, loss of function in the brain region that is fed by the occluded vessel. A hemorrhagic stroke causes a similar injury with a bleeding within the brain tissue or bleeding into the subarachnoid space, the area between the membranes of the brain called arachnoid membrane.  There are many causes of this disease.  These are;

Atherothrombotic occlusion of large vessel: It is the occlusion of large or medium vessels that provide blood supply to the brain.  This type of occlusion is composed of stages: a plaque called atherosclerosis grows in the largest vessels of the brain (carotids), it narrows the vessel walls, ruptures from its localization and causes occlusion in one of the vessels close to the brain and within the brain. Approximately 20% of patients have this cause.

Lacunar occlusion of small vessel: 40% of the patients are in this group.  It occurs by the occlusion of small vessels in the brain.  It causes small infarct areas in important deep structures of the brain such as basal ganglia, internal capsule and brain stem.  The area formed after infarction is called "lacuna".

Cardioembolic occlusion: It is a pathology that accounts for 20% of cerebrovascular occlusions. It mostly occludes medium blood vessels of the brain and medium blood vessels that provide blood supply to the posterior part of brain, called vertebrobasilar system.  More than half of them occur as a result of a heart disease called atrial fibrillation.

Occlusion due to other causes: It accounts for 20% of cerebrovascular occlusions. Diseases such as arterial dissection, fibromuscular dysplasia, Moyamoya can be included in this group.

As the blood flow reduces below the critical level needed for nerve cells, a chain of biochemical reactions begins and it results in cell death in a particular region. Consequently, clinical symptoms may vary depending on the degree of ischemia, the volume of the affected region, the functional characteristics of this region and the duration of the effect.  However, headache is seen in 25% of patients and is the most common finding.  If an ischemia (oxygen-free zone) involving a very large part of the brain occurs, it is referred to as focal ischemia.  4 common clinical pictures show up due to veno-occlusive diseases;

1- Transient (temporary) ischemic attack (TIA): It is temporary neurological disorders that take less than 24 hours.  Most of them take 10-15 minutes therefore, the diagnosis may remain limited only with the anamnesis. Dizziness, gait abnormality, speech disorder, monocular visual impairment and sometimes one-sided weakness (loss of strength) are the most common symptoms.  A TIA that occurs more than one may be a precursor to a further total stroke (rates have been reported to be between 20-80%).

2- Reversible ischemic neurologic deficit: It takes more than 24 hours and the term is used for clinical conditions recovering completely before 3 weeks.  Embolism of cardiac origin is commonly held responsible.  There is a risk of total stroke in the future.

3- Progressive Stroke : It is the term used for cases in which focal ischemic findings worsen within minutes or hours.  At the beginning, it occurs with the expansion of the affected area.  This condition is usually completed within 48 hours.  It may take longer if it occurs in the system that provides blood supply to the posterior part of the brain.

4- Cerebral infarct : There are stabilized ischemic neurological deficits.  Embolic strokes begin suddenly, the maximum neurological disorder occurs early and finishes, and recovery may take hours, days or months.  Such patients often wake up with a cerebral infarct and deficit.

5- Stroke in young adult : The likelihood of stroke is very little for a non-diabetic and non-hypertensive person aged below 40 years.  The most common cause of a stroke for this age group is the embolism of cardiac origin.  However, although rare, drug abuse, particularly cocaine, arterial dissection, fibromuscular dysplasia and coagulation disorders should be remembered.

Early diagnosis is very important.  Other diseases that may be mistaken for this disease should be eliminated.  These are the diseases such as brain tumours, infections of the brain (abscess-encephalitis), postictal state, trauma, subdural hematoma, hysteria, contusion, hyperglycemia, hypoglycemia, disorders of cardiac function.  Various blood tests, cranial tomography, cranial MRI, Doppler USGs, MRI angiography are performed to make a diagnosis.

Firstly immediate treatment is necessary for acute stroke and in the long term, factors such as diabetes, hypertension, atrial fibrillation, hypercholesterolaemial, overuse of alcohol-smoking and physical inactivity are advised to be eliminated.  Besides these, treatment of underlying causes, preventive treatment, surgery and endovascular surgical treatments can be administered. Physical therapy and rehabilitation treatments can also be administered if neurological disorders such as paralysis of any arm or leg have occurred.