The slow phasing movement of a normal physiology to a disease causing pathology is dealt in Nidan Panchak.
Diagnosis of a disease, knowledge of its origin, and tracing evolution can be done through Nidan in Ayurveda.
The descriptions of the tools are as follows:
Hethu, the causative factors are responsible for leading to the disease causing pathologies. Internal or Nija, and External or Agantu are the two types of hetu. The balance of the three doshas like Vata, Pitta and Kapha can be disturbed by the hetus. Hetu is further classified into different factors depending upon which dosha’s equilibrium is disturbed. They are close factor, distant factor, weak factor, and string factor. Asatmiya Indriyartha Sanjog, Pragyapradh, Parinama or time, Dosha hetu, diseased factor, combined factor, predisposing factor, exciting factor, external factor, and internal factors are also included in Hethu.
Poorvaroop are the signs and symptoms that develop during the development of pathology of the disease.
Pathology deals with the manifestation of function of a disease and anatomy.
With these signs and symptoms, we will be able to identify the disease, and this is Poorvaroop, which is of two types: Samanya Poorvaroop or general preindicating signs and symptoms, and Vishesh Poorvaroop or special indicating signs and symptoms.
While Samanya poorvaroop helps us identify the disease in the broader sense from the general preindicating symptoms or signs that show during the development of disease; however, does not help in diagnosing the sub type of the disease or the exact disease.
Vishesh poorvaroop helps us identify both the disease and its sub type with the help of special preindicating signs or symptoms.
The signs and symptoms that appear only after the disease development help in diagnosing the disease, and this is known as Roop or indicative signs and symptoms. Roop is also known as Sansthan, Vainjan, Linga, Lakshan, Chinham or Akruthi.
It is also known as therapeutic test that help to treat an ailment through medicine, diet and conduct. The different types of treatments are: Hethuviprit or anti factor, Vyadhiviprit or anti disease, hethuvyadhiviparit or anti factor and disease), hetuviprithkari or anti causative subjective, vyadhivipritkari or anti disease subjective and Hetu-Vyadhivipritkari or anti factor or anti disease subjective.
Each factor has their own sub factors. The Anti factor is divided into Hetuviprit aushadi, hetuviprit anna, and hetuviprit vihara. The disease factor is divided into vyadhiviprit aushadhi, vyadhiviprit anna, and vyadhiviprit vihar.
The anti factor and anti disease factor is divided into hetuvyadhiviprit aushadhi, hetuvyadhiviprit anna, and hethuvyadhiviprit vihar. The anti causative subjective factor is divided into medicine, diet and conduct. The anti disease subjective is divided into medicine, diet and conduct. The anti factor & anti disease subjective is again divided into medicine, diet and conduct again.
It is known as Pathology in English, and in Sanskrit, it is Jati and Agati. From the disturbance of equilibrium of doshas, and undergoing different stages, to the causing of the disease, the process is known as Samprapti. Sanchaya, prakop, prasar, sthansanshraya, vyakti, and bheda are the different stages in Samprapti.