**4.4 Type of population**

The age of the patients is other aspect to discuss. A review performed in children (acupuncture to prevent postoperative nausea) has been published without conclusion about its effectiveness [34]. Quincer et al. [96] showed the case of a 5-year-old boy who developed a Nicolau Syndrome after an intramuscular injection in deltoid. Besides, cases of elderly people who have suffered syncope's due to acupuncture have also been described [28]. These patients (the most prevalent population in the outpatient) may be more debilitated and suffer more adverse effects even taking precautions.

There are some types of population could be considered "at risk" when using these needling techniques, like pregnant women. We have found an article that exposes a retrosternal abscess due to sternoclavicular joint injection with resolution [82]. McDowell et al. have developed a review on the safety of acupuncture and dry needling in pregnant women in New Zealand. They conclude that of 124 responses obtained, only 60 therapists needle pregnant women and only 66% of them express safety. More training is needed in this field, particularly on dry needling [120].

In relation to sex, only one article showed major incidence in men than in woman [70].
