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.
There are very few known causes of primary tumors, although certain genetic syndromes may increase risk including: 1  Neurofibromatosis type 1 and 2 are nerve tumors of the skin, brain or spinal cord. Problems with the NF1 gene are much more likely to be implicated as a cause of brain tumors than changes to NF2.