Chronic pain is one of the main leading causes of physical and emotional disability, social disruption, and work absenteeism. Neuromodulation with SCS is one of the most exciting modalities for managing refractory chronic pain . The mechanism of its action is believed to be through inhibiting pain by stimulating the large diameter afferent nerve fibers in the spinal cord, which is based on the gate control theory of pain proposed by Melzack and Wall . Previous work showed the effectiveness of SCS in cases of FBSS not responding to conventional medical treatment.
In our case series, patients’ pain level measured by VAS score decreased significantly in both conventional SCS and position adaptive SCS groups. The results were similar to previous randomized trials [5, 6, 13,14,15,16]. Furthermore, position adaptive SCS was superior over conventional SCS in reducing VAS score (p > 0.001). Similarly, Shultz and colleagues  demonstrated that automatic position-adaptive stimulation is effective in terms of patient-reported pain relief and convenience compared with using manual programming.
Ramineni and colleagues reported that pain lessening after SCS increased sleep quality and improved quality of life . Likewise, our results proved to be concomitant as patients’ quality of sleep after both conventional and position adaptive SCS patient populations was observed to improve significantly (p < 0.001). Position adaptive SCS patients’ group showed better sleep quality compared to conventional SCS, this could be attributed to the ability of Position adaptive SCS to prevent pain bouts that can be triggered by changing position during sleep.
The role of SCS in reducing opioids analgesic demand was controversial. Several studies reported a significant decrease in the use of opioid analgesics after SCS operation [15, 18, 19]. Another study, however, argued that SCS operation did not result in a decrease in opioid need . In our study, we evaluated changes in patients’ analgesic usage after SCS implantation. We found that 50% of patients stopped using their opioid medication after SCS implantation while 75% stopped using opioids in the position adaptive SCS group. Nevertheless, the difference between the two groups was not statistically significant.
In our study, we analyzed the satisfaction levels of patients after SCS. In the position, adaptive SCS group, 79.4% of cases were satisfied after treatment (55.9% reported excellent satisfaction) whereas in the conventional SCS group 50% of cases were satisfied (14.5% with excellent satisfaction). Similarly, In the multicentric prospective randomized control study by Kumar and colleagues . and the large trial done by Sanders and colleagues reported that 84.27% of the patients were satisfied with SCS implantation . Improvement in daily activities of patients is an important indicator of the efficiency of treatment. In our study, 51.6% of the patients reported more than 50% improvement in their daily activities while 43.5% reported less than 50% improvement. Similar results were conformed in many studies [10, 16, 18].
Our study had some limitation including unknown analgesics dosages. Reasons for this were patients’ low socio-cultural and educational levels and irregular drug usage. Therefore, information related to analgesics usage in our patient follow-up records were evaluated such as “using in the same way," "reduced dosage," and "not using". Follow-up of pain relief and patient satisfaction was studied after 3 months only yet, longer study duration would be favorable in confirming the results.
In conclusion, SCS is an efficient and reliable treatment modality in chronic pain palliation in line with the findings of our study and other supporting studies found in the literature. Moreover, MR-compatible sensor-driven position adaptive SCS may be preferred in terms of clinical effectiveness, patient satisfaction, and ease of use compared to conventional SCS.