**2. History of scalp acupuncture**

The earliest medical record for the application of acupuncture on scalps can be traced back to around 5 BC [7]. Since then, experiences accumulated with the utilization of acupuncture on the scalp in treating various illnesses. Along with the establishment of TCM theories, it had been a component in traditional acupuncture system. Until the 1950s, acupuncture experts started to observe and recognize the relationship between illnesses and subscalp spots. Inspired by micropuncture systems concepts and influenced by anatomical and physiological knowledge from modern medicine, new theories and new needling techniques had been established [8]. In the 1970s, acupuncturists from different areas of China developed their own schools of theory, and several scalp acupuncture systems have been suggested. Despite variations present in theoretical concepts, sites of acupuncture (acupoints), and nomenclature among different schools, many areas such as the clinical indication and treatment procedures share common ground. Most recognized theories include the adaptation of knowledge in cerebral anatomy, physiology, neurology, and reflexology. Owing to the impressive therapeutic effect of scalp acupuncture in treating brain diseases as well as other illnesses, there was a strong urge to facilitate academic exchange and promote scalp acupuncture to wider communities. Intensive efforts had been made in standardizing the names of the scalp acupoints. By the time the World Health Organization (WHO) set up an international standard scalp acupuncture nomenclature systems in 1989, scalp acupuncture had been already extensively applied by therapists and acupuncturists around the globe [9]. Some places like the USA and Japan had even developed their own understandings in the field of scalp acupuncture [10, 11]. In short, scalp acupuncture is a technique derived from TCM, yet its theory and application involves multiplicity of systems that have been rapidly developing in the recent decades.
