Electroconvulsions may cause anxiety and headaches. Electroconvulsive shock can cause transient degenerative memory deficits, and memory loss for up to 30 minutes after a convulsive episode. This memory deficit can develop if treatment is repeated over a short period of time. If treatment is given only 2-3 times a week, this memory deficit does not occur, and some patients can experience confusion, headache, nausea, and vertigo lasting for hours after treatment. With modern technology, some modern measures can make this side effect, very mild and quite short-lived. Unilateral electroconvulsive therapy has very few side effects, a few patients have muscle pain, especially in the jaw, and a few reports of disseminated grand mal seizures within a month of treatment. However, there may be other causes for such seizures, and if seizures occur, they are usually only seen within a year of treatment. Occasionally there are injuries to the teeth, tongue and lips, and possibly minor electrical burns in the electrode area if the cotyledon and tracheal tube are not properly placed. Fractures, including compression fractures of the vertebrae, can occasionally occur if muscle relaxants are not given at the time of treatment. Such injuries to the trunk are rare if good anesthesia has been given beforehand and the convulsions have been properly ameliorated.