By: Dr. B

Dr. B — Thu, 12 Nov 2009 17:06:59 +0000

It would not let me answer your other question for some reason right now, so I will try to here.
Central venous thrombosis (CVT) is a condition in which a blood clot forms in the veins/sinuses that drain the brain. These veins are separated into the superficial and deep venous systems and drain into special veins called sinuses. It is helpful to distinguish superficial vs. deep, because CVT in the deep vessels has a worse prognosis., Cortical veins are part of the superficial venous system. Cortical vein thrombosis without sinus involvement is rarely diagnosed, although it may commonly be overlooked, because it is difficult to diagnose, both clinically and radiologically. CVT accounts for 1-2% of strokes. Symptoms include: headache (Most common symptom), disturbances of consciousness and cognitive dysfunction, focal neurologic deficits (Stroke like symptoms, eg. Paralysis of one side of the body, speech difficulty, visual field defects), and seizures. There are at least two different mechanisms that may contribute to the clinical features of CVT. Thrombosis of cerebral veins or dural sinus can lead to damage of normal brain tissue with resulting dysfunction. The clot increases the pressure in the venous system and can lead to surrounding brain swelling (edema) and also bleeding into the brain tissue (intracranial hemorrhage.) There can also be impairment in emptying the CSF fluid that is the fluid that surrounds the brain and spinal cord. This can lead to a buildup in CSF fluid (hydrocephalus) and increased pressure around the brain (increased intracranial pressure.) These events do not occur in all patients with CVT, but are possible.
Several conditions can increase the risk of having a CVT. It is recommended that all adults with CVT be evaluated for these risk factors. The risk factors include: Hypercoagable states in which there is an increased risk of forming blood clots. There are certain blood tests a doctor can check to evaluate for these condtions. Other risk factors include, oral contraceptive use, pregnancy, cancer, infection and head injury
Diagnosis is made with MR venography or CT venography. If the clinical suspicion is high and the CT or MRI was normal, then cerebral venous angiogram may be performed in which the doctors enter the venous system and shoot IV dye to evaluate for clot. Cortical vein thrombosis is more difficult to diagnose than thrombosis of the other sinuses. There is a sign on imaging called the "cord sign" that is specific to cortical vein thrombosis, but it may not always be present.
The treatment of CVT is with medications that thin the blood to help dissolve the clot and prevent future clots from occurring. It is also important to treat the underlying cause if possible to prevent future clot formation. The medications used to thin the blood include heparin and Coumadin (Warfarin). Heparin is used initially can be given through an IV (unfractionated heparin) continuously or there are formulations called low molecular weight heparin that can be given by subcutaneous injection once or twice daily. Unfractionated heparin through the IV requires frequent lab monitoring (aPTT), so low molecular weight heparin is usually preferred. . After the patient has been on heparin, then oral Coumadin will be started. Coumadin thins the blood in a different way and the therapeutic effects can be monitored with a blood test called the PT/INR. Goal INR is 2-3 in most cases of CVT. Heparin can be discontinued once the INR is in the therapeutic range. The length of Coumadin therapy is debated, but it is dependent on the cause and the reversibility of risk factors for future clot. Generally, Coumadin therapy is recommended for 6-12 months, for most patients. Thrombolytics (clot busting medication) can also be used in some cases, but has not been extensively researched. It is reserved for patients with deteriorating clinical status on Heparin/Coumadin. The decision to use thrombolytics is based on the risk benefit ratio.
In regards to prognosis, CVT can result in death or permanent disability, but usually has a favorable prognosis. Since cortical vein thrombosis is a rare type of CVT the prognosis has been less studied, but is believed to be more favorable than CVTs in general. A study known as the International Study on Cerebral Vein and Dural Sinus Thrombosis (ISCVT) evaluated 624 patients (age >15 years) with CVT found that 27 patients (4.3 percent) died during the acute phase, and 21 (3.4 percent) died within 30 days from symptom onset. At 16 months follow up, 57% of patients had a complete recovery and only 2.2% had severe functional impairment. Factors associated with a worse prognosis, included depressed level of consciousness (coma), altered mental status, thrombosis in the deep venous system, right hemisphere hemorrhage, and lesions located towards the back of the brain (posterior fossa lesions.) There was a meta-analysis performed to evaluate long term outcomes by reviewing the results of several studies. They found that CVT was associated with a 15% overall death or dependency rate at follow up. They observed that the risk of death was related to underlying conditions. The predictors of poor long-term outcomes observed were infection in the central nervous system (encephalitis, meningitis), any cancer, thrombosis in the deep vein system, hemorrhage into the brain tissue, coma, abnormal mental status, age > 37, and male gender. So, overall prognosis is good if it is treated early with appropriate medications. You should discuss this with your doctor who would know the full details of the case, evaluation and treatment. I am not sure if you have this condition or someone you know. I hope I helped answer your question. Sorry if it is too technical. If you have any questions, let me know. Feel free to email me if you do. Good luck.
References :
Physician, UpToDate

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By: Dr. B