This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Which of the following is used to treat pain 
Select and explain. 
A. Subcaudate tractotomy, B. Cingulotomy, C. Transcutaneous nerve stimulation, D. All of the above
C: Transcutaneous nerve stimulation
Answer: C: Transcutaneous nerve stimulation 
Explanation: There are various modalities of treatment which are tried for chronic pain:-
i) Pharmacotherapy:- The various drugs (mentioned above) are used for chronic pain syndrome. The various routes can be used:- oral, intravenous, epidural, or Transcutaneous.
ii) Neuro-surgical:- Anterolateral cordotomy, dorsal root entry zone lesion, selective rhizotomy, commissural myelotomy, sympathectoning mesencephalic tractomy, cordectomy
iii) Chemical neurolysis:- Glycerol, alcohol, phenol e.g. intrathecal hyperbaric phenol.
iv) Other:- Acupuncture, transcutaneous electric nerve stimulation, neuromodulation procedures (intracranial stimulation:- deep brain/subcortical and motor cortex stimulation), cryoablation.