All parts of the jimsonweed plant are poisonous to horses and humans; toxicity is caused by tropane alkaloids. Symptoms of poisoning in horses include a weak, rapid pulse, dilated pupils, dry mouth, incoordination, diarrhea, convulsions, coma, and sometimes death.
Meningioma Causes. The causes of meningioma are not yet fully understood. In fact, several research studies suggest that many meningiomas develop spontaneously, or without a known cause. Sometimes, these tumors can disappear spontaneously as well. Meningiomas, like other solid tumors, develop when healthy cells undergo genetic mutations that cause them to replicate uncontrollably.
What You Need to Know. 1  Meningioma is the most common type of primary brain tumor, accounting for about 30 percent of all brain tumors. 2  Meningiomas can grow and press against the brain or spinal cord, causing symptoms such as: Headaches. 3  About 85 percent of meningiomas are benign and most can be removed with surgery.