Quoted from wikipedia:
The procedure was popularised in the United States when Walter Freeman invented the "ice pick lobotomy" procedure, which literally used an ice pick and rubber mallet instead of the standard surgical leukotomy. Leaving no visible scars, the ice pick lobotomy was heralded as a great advance in "minimally invasive" surgery, and was eventually done under only local anaesthesia.
In a minimally invasive procedure, Freeman would hammer the ice pick into the skull just above the tear duct and wiggle it around. Between 1936 through the 1950s, he advocated lobotomies throughout the United States. Such was Freeman's zeal that he began to travel around the nation in his own personal van, which he called his "lobotomobile", demonstrating the procedure in many medical centres. He reputedly even performed a few lobotomies in hotel rooms.
Freeman's advocacy led to great popularity for lobotomy as a general cure for all perceived ills, including misbehaviour in children. Ultimately between 40,000 and 50,000 patients were lobotomised. A follow-up study of almost 10,000 patients claimed 41% were "recovered" or "greatly improved", 28% were "minimally improved", 25% showed "no change", 4% had died, while only 2% were made worse off (Tooth, et al. 1961). Lobotomies gradually became unfashionable with the development of antipsychotics and are no longer performed. The era of lobotomy is now generally regarded as a barbaric episode in psychiatric history.