Basti Karma as such is a colloidal enema systematically induced in large intestine. After adminsitration within a prescribed time the drug passes out along with fecal matter and the humors as explained in classical literature. This can indirectly create a negative pressure inside the abdomen cyclically for a period of adminsitration ranging from 8-30 days ( yoga basti - Kala basti). This cyclic intra abdominal negative pressure can cause relapse of a bulged disc or a compressed nerve and letting it set back in its own position. This os the reason why Basti karma is found to be highly beneficial in back ache other than its theraupetic mode of action.
Nature is as simple as it is, but we human understand it on our own ways and making things complex. Human body is representative of nature and whatever happens in nature it affect human body. We Ayurveda people consider Tridosha, Dhatu and Mala as as a Sharira.
We can choose the treatment modalities as:
Sthanbheden: Shodhan Chikitsa
Lakshana bheden: Shaman Chikitsa
If the disease is due to Vata Dosha predominance and the Sthana of Vata is Pakvashaya, Kati and Sakthi then Vasti is considered for Shodhana.
And
If the patients having having Roga Lakshana then the causative Dosha and the Guna responsible for that Lakshana has to be considered for the Shamana Chikita (also called as Viparita Guna Chikitsa)
Asthapana and Anuvasana types of Basti (enema) for the cure of Vatika Vikara because immediately after entering the colon, they strike at the very root of the vitiated Vata and when it is overcome in the colon, even the entire vitiated
Vata dwelling in other parts of the body automatically alleviated.