Causes
Disorders that cause, or increase the risk for systemic venous thrombosis are associated with central venous thromboses. In children, head and neck infections and acute systemic illnesses are the primary cause of central venous thrombosis. Cerebral venous sinus thrombosis is more common in particular situations. 85% of people have at least one of these risk factors:
Thrombophilia, a tendency to develop blood clots due to abnormalities in coagulation, e.g. factor V Leiden, deficiency of protein C, protein S or antithrombin, or related problems
Nephrotic syndrome, a kidney problem causing protein loss in the urine
Chronic inflammatory diseases, such as inflammatory bowel disease, lupus and Behçets disease
Pregnancy and puerperium (the period after giving birth)
Particular blood disorders, especially polycythemia vera and paroxysmal nocturnal hemoglobinuria
Use of estrogen-containing forms of hormonal contraception
Meningitis and infections of the ear, nose and throat area such as mastoiditis and sinusitis
Direct injury to the venous sinuses
Medical procedures in the head and neck area
Obesity, especially in combination with oral contraceptive use 
Sickle cell anemia
Dehydration, primarily in infants and children
Homocysteinemia
Homocystinuria

Diagnosis
The diagnosis may be suspected on the basis of the symptoms, for example the combination of headache, signs of raised intracranial pressure and focal neurological abnormalities, or when alternative causes of headache and neurological abnormalities, such as a subarachnoid hemorrhage, have been excluded. Imaging
There are various neuroimaging investigations that may detect cerebral sinus thrombosis.
), an immunosuppressive drug frequently used to prevent transplant rejection; the two drugs should therefore not be administered concomitantly. Orlistat can also impair absorption of the antiarrhythmic amiodarone. The Medicines and Healthcare products Regulatory Agency (MHRA) has suggested the possibility that orlistat could reduce the absorption of antiretroviral HIV medications. Mechanism of action
Orlistat works by inhibiting gastric and pancreatic lipases, the enzymes that break down triglycerides in the intestine. When lipase activity is blocked, triglycerides from the diet are not hydrolyzed into absorbable free fatty acids, and instead are excreted unchanged. Only trace amounts of orlistat are absorbed systemically; the primary effect is local lipase inhibition within the GI tract after an oral dose. The primary route of elimination is through the feces. Orlistat was also found to inhibit the thioesterase domain of fatty acid synthase (FAS), an enzyme involved in the proliferation of cancer cells but not normal cells. However, potential side effects of orlistat, such as inhibition of other cellular off-targets or poor bioavailability, might hamper its application as an effective antitumor agent. One profiling study undertook a chemical proteomics approach to look for new cellular targets of orlistat, including its off-targets. Orlistat also shows potential activity against the Trypanosoma brucei parasite.Orlistat prevents approximately 30% of dietary fat from being absorbed. Legal status
Orlistat is available both with and without a prescription. Australia and New Zealand
In Australia and New Zealand, orlistat is available as a "Pharmacist Only Medicine.