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.
Doctors do not know what causes primary brain tumors. However, several risk factors have been identified. 1  Some genetic diseases put you at risk for brain tumors. 2  These include Turcot syndrome (a condition characterized by abnormal cells and polyps) and neurofibromatosis (a tumor-causing genetic disorder).