## 3 Results
### Bibliometric Analysis of Publication Output
Abbreviation: RCT—randomized controlled trial. Figure 6: Most relevant topics (n = 1652). One or more topics were recorded for each article. Acute and chronic cancer and noncancer pain conditions were addressed. The topic “efficacy” was prevalent (n = 212, 12.81%). Abbreviations: CRPS—complex regional pain syndrome; LBP—low back pain; TENS—transcutaneous electrical nerve stimulation. The most cited article (1772 citations) was published by [PERSON] et al. [19] in 2015. It is a review of the theoretical, physiological, and practical aspects of different neuromodulation strategies released by the International Federation of Clinical Neurophysiology (IFCN). The top cited articles [19; 20; 21; 22; 23; 24; 25; 26; 27; 28] are reported in Table 2. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Author(s)** & **Article Title** & **Journal** & **Quartile** & **Citations (n)** & **Year** \\ \hline \multirow{4}{*}{[PERSON], et al. [19]} & “Non-invasive electrical and magnetic stimulation of the brain, spinal cord, roots and peripheral nerves: Basic principles and procedures for routine clinical and research application. An updated report from an IFCN Committee” & \multirow{4}{*}{Q2} & \multirow{4}{*}{1772} & \multirow{4}{*}{2015} \\  & & & & \\ \cline{1-1} \cline{5-6}  & & & & \\ \cline{1-1} \cline{5-6}  & & & & \\ \hline \multirow{4}{*}{[PERSON], et al. [20]} & “Current and Future Issues in the Development of Spinal Agents for the Management of Pain” & \multirow{4}{*}{_Pair_} & \multirow{4}{*}{Q1} & \multirow{4}{*}{635} & \multirow{4}{*}{1992} \\ \cline{1-1} \cline{5-6}  & & & & \\ \hline \multirow{4}{*}{[PERSON], et al. [21]} & “EFNS guidelines on neurostimulation therapy for neuropathic pain” & \multirow{4}{*}{_Eur_} & \multirow{4}{*}{_J Neurol_} & \multirow{4}{*}{Q1} & \multirow{4}{*}{420} & \multirow{4}{*}{2007} \\ \cline{1-1} \cline{5-6}  & & & & & \\ \cline{1-1} \cline{5-6}  & & & & & \\ \hline \multirow{4}{*}{[PERSON], et al. [23]} & “Imaging attentional modulation of pain in the periaqueductal gray in humans” & \multirow{4}{*}{_J Neurosci_} & \multirow{4}{*}{Q1} & \multirow{4}{*}{391} & \multirow{4}{*}{2002} \\ \cline{1-1} \cline{5-6}  & & & & & \\ \hline \multirow{4}{*}{[PERSON], et al. [24]} & “Origin of pain in migraine: evidence for peripheral sensitization” & \multirow{4}{*}{_Lancet Neurol_} & \multirow{4}{*}{Q1} & \multirow{4}{*}{366} & \multirow{4}{*}{2009} \\ \cline{1-1} \cline{5-6}  & & & & & \\ \hline \multirow{4}{*}{[PERSON], et al. [25]} & “Neuromodulation appropriateness Consensus Committee. The appropriate use of neurostimulation of the spinal cord and peripheral nervous system for the treatment of chronic pain and ischemic diseases: the Neuromodulation Appropriateness Consensus Committee” & \multirow{4}{*}{Q3} & \multirow{4}{*}{347} & \multirow{4}{*}{2014} \\ \cline{1-1} \cline{5-6}  & & & & \\ \hline \multirow{4}{*}{[PERSON] [PERSON], et al. [26]} & “The lower limb flexion reflex in humans” & \multirow{4}{*}{_Prog Neurobiol_} & \multirow{4}{*}{Q1} & \multirow{4}{*}{339} & \multirow{4}{*}{2005} \\ \cline{1-1} \cline{5-6}  & & & & \\ \cline{1-1} \cline{5-6}  & & & & \\ \hline \multirow{2}{*}{[PERSON], et al. [27]} & “Repairing injured peripheral nerves: Bridging the gap” & \multirow{2}{*}{_Prog Neurobiol_} & \multirow{2}{*}{Q1} & \multirow{2}{*}{339} & \multirow{2}{*}{2010} \\ \cline{1-1} \cline{5-6}  & & & & \\ \hline \multirow{2}{*}{[PERSON] [PERSON], et al. [28]} & “Neuromuscular electrical stimulation in neurorehabilitation” & \multirow{2}{*}{_Muscle Nerve_} & \multirow{2}{*}{Q2} & \multirow{2}{*}{333} & \multirow{2}{*}{2007} \\ \cline{1-1} \cline{5-6}  & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Summary of the most cited articles. Abbreviations: Q—quartile. Figure 7: Citations analysis. Means and standard deviations for different time intervals: 1990–99 (55.1, 71.2); 2000–10 (57.2, 70.7); 2011–15 (43.7, 127.5); >2015 (22.8, 43.3).