Modified radical mastectomy (MRM) is one of the most commonly performed surgical procedures for breast cancer and is associated with significant intraoperative stress and moderate-to-severe postoperative pain. Effective perioperative analgesia is essential to improve patient comfort, facilitate early mobilization, reduce opioid consumption, and enhance postoperative recovery. Although general anaesthesia remains the standard anaesthetic technique for MRM, it is associated with postoperative nausea and vomiting, increased opioid requirements, delayed recovery, and airway-related complications. These limitations have prompted interest in regional anaesthetic techniques as alternatives or adjuncts to general anaesthesia.¹

Segmental thoracic spinal anaesthesia (STSA) has emerged as a safe and effective regional anaesthetic technique for breast and upper abdominal surgeries. By administering a low dose of local anaesthetic at the thoracic level, STSA provides a dense sensory block confined to the required dermatomes while minimizing unnecessary sympathetic blockade, resulting in stable hemodynamics, excellent surgical conditions, and superior postoperative analgesia^4,5

Adjuvants such as clonidine and dexmedetomidine are frequently added to intrathecal local anaesthetics to prolong the duration of sensory block and postoperative analgesia. Both drugs are selective α₂-adrenergic receptor agonists that enhance analgesia by inhibiting nociceptive transmission in the dorsal horn of the spinal cord. Clonidine has been widely used because of its analgesic and sedative properties; however, dexmedetomidine possesses a much higher α₂:α₁ receptor selectivity (approximately 1600:1 versus 220:1 for clonidine), producing prolonged analgesia and better quality of neuraxial blockade with minimal respiratory depression.^6,7

Several studies have demonstrated that intrathecal dexmedetomidine provides a longer duration of sensory block, prolonged postoperative analgesia, improved sedation, and reduced analgesic consumption compared with clonidine in lower abdominal and lower limb surgeries. However, evidence comparing these adjuvants during segmental thoracic spinal anaesthesia for modified radical mastectomy remains limited. Therefore, the present randomized controlled study was undertaken to compare the efficacy and safety of intrathecal clonidine and dexmedetomidine as adjuvants to segmental thoracic spinal anaesthesia in patients undergoing modified radical mastectomy.

The present study was conducted at Chamarajnagar institute of medical sciences, chamarajnagar, Karnataka. This was a randomised controlled study conducted in a tertiary care hospital among the 60 female patients aged 18 and 65 years. To evaluate the analgesic effects of intrathecal clonidine vs dexmedetomidine in isobaric bupivacaine for thoracic spinal anaesthesia in patients undergoing breast surgery. Patients aging with ASA class I or II undergoing elective breast surgery (modified radical mastectomy for carcinoma breast) and BMI < 35 Kg/m2 were included in this study. The exclusion criteria were patient with bleeding disorder and cardiovascular disease; presence of infection in the site of block; known allergy to local anesthetic; patients with abnormalities of the spine (kyphosis or scoliosis), and in cases with a change in surgical plan or more than two attempts for performing regional anaesthesia procedure. After arrival in the operating room, an 18G IV cannula was inserted in a peripheral vein and infusion of balanced crystalloid solution was started. Patient’s baseline vital parameters were recorded using pulse oxymeter, ECG and non-invasive blood pressure (NIBP). Patients were placed in sitting position and T5-T6 intervertebral space was identified. Under full aseptic precautions and skin infiltration with (1% lignocaine) local anesthetics, a Quincke’s babcock spinal needle 25G was placed in mid-line/paramedian approach. Correct placement was confirmed by free flow of clear CSF. Then, Group C: 1 ml of 0.5% isobaric levobupivacaine (5 mg) mixed with 0.2 ml of clonidine (30 microgram) was injected Group D: 1ml of 0.5% isobaric levobupivacaine (5 mg) mixed with 0.2ml of dexmedetomidine (20 microgram ) was injected and patients were placed in supine position immediately. After that, clinical examination was done to assess the sensory and motor block along with heart rate, blood pressure, and SpO2. The vital parameters were recorded in regular interval until the end of surgery. The level of sensory block was assessed by pinprick, and motor block was assessed by Epidural scoring scale for arm movements (ESSAM) score for upper limb [hand grip (T1/C8), wrist flexion (C8/C7), and elbow flexion (C6/C5)]15 and modified Bromage scale for lower limb (0 = able to lift extended legs; 1 = just able to flex knees, full ankle movement; 2 = no knee movement, some ankle movement; 3 = complete paralysis).Once the block was considered adequate (minimum block T2–T8), and patients were sedated by 1 mg midazolam intravenously. All patients were given oxygen supplementation at 5 L/min with facemask. Adverse effects were treated accordingly e.g hypotension with ephedrine, bradycardia with atropine as i.v. boluses as required, and nausea or vomiting was treated with Ondansetron 4 mg. After surgery, patients were transferred to the recovery room. The objectives of this study were intraoperative hemodynamic changes, perioperative complications, time of first rescue analgesic, total paracetamol consumption in first 24 hours. Statistical analysis: Collected data were analyzed using SPSS (Statistical Package for Social Sciences) for Windows, version23.0. Qualitative variables were expressed as frequency and percentages. Quantitative data were expressed in mean ± standard deviation. The results were presented using tables and figures.

This was a randomized controlled study conducted among the 60 female patients undergoing Modified Radical Mastectomy (MRM) under Segmental Thoracic Spinal Anaesthesia (STSA) comparing with Clonidine vs Dexmedetomidine. These 60 patients were randomly allocated in to dexmedetomine + levoBupivacaine group (30 patients) and Clonidine + levoBupivacaine group (30 patients).

Table 1: Demographic Characteristics

 No statistically significant difference in baseline characteristics.

Table 2: Characteristics of Spinal Block

Table 3: Duration of Analgesia

The time to first rescue analgesic was significantly longer in the dexmedetomidine group compared with the clonidine group (488 ± 49 vs 355 ± 41 minutes; P < 0.001)

Table 4: Intraoperative Heart Rate (beats/min)

Heart rate decreased after STSA in both group. Both the group produced comparable hemodynamic stability during segmental thoracic spinal anaesthesia.

Figure 1: Comparison of HR between two groups

Table 5: Intraoperative Mean Arterial Pressure (MAP, mmHg)

MAP decreased after STSA in both groups and remained within clinically acceptable limits throughout surgery. There was no statistically significant difference in MAP

Table 6: Pain Scores (VAS)

VAS pain scores were consistently lower in the dexmedetomidine group throughout the first 24 hours.

Figure 2: Comparison of VAS between group C and D

The present randomized controlled study compared the efficacy and safety of intrathecal clonidine and dexmedetomidine as adjuvants to segmental thoracic spinal anaesthesia (STSA) in patients undergoing modified radical mastectomy. The demographic characteristics and baseline hemodynamic parameters were comparable between the two groups, indicating successful randomization and minimizing confounding factors.

Our study demonstrated that dexmedetomidine produced a faster onset of sensory and motor block, prolonged the duration of sensory blockade, and significantly increased the duration of postoperative analgesia compared with clonidine. These findings are consistent with the study by Kanazi et al., who reported that intrathecal dexmedetomidine prolonged sensory and motor blockade more effectively than clonidine when added to bupivacaine. Similarly, Gupta et al. observed that dexmedetomidine significantly extended postoperative analgesia while reducing analgesic consumption compared with clonidine, supporting the superior analgesic efficacy of dexmedetomidine.6,7

In the present study, postoperative pain scores assessed using the Visual Analogue Scale (VAS) were significantly lower in the dexmedetomidine group throughout the first 24 postoperative hours. Consequently, patients receiving dexmedetomidine required fewer rescue analgesics than those receiving clonidine. These findings agree with those of Al-Mustafa et al., who demonstrated prolonged analgesia and reduced postoperative analgesic requirements following intrathecal dexmedetomidine. Similar observations have also been reported by Gupta et al., highlighting the role of dexmedetomidine in improving postoperative pain management.7,8

The superior analgesic effect of dexmedetomidine can be explained by its high α2-adrenoceptor selectivity, which is approximately eight times greater than that of clonidine. Activation of presynaptic α2 receptors inhibits norepinephrine release, whereas postsynaptic receptor activation in the dorsal horn suppresses nociceptive transmission, resulting in prolonged sensory blockade and enhanced analgesia. These pharmacological properties have been well described by Eisenach et al. and Grewal.¹⁰˒¹¹

Both groups maintained satisfactory intraoperative hemodynamic stability throughout surgery. HR, mean arterial pressure remained comparable between the groups. Similar hemodynamic findings have been reported by Kanazi et al. and Gupta et al., confirming that intrathecal dexmedetomidine provides stable cardiovascular conditions when used in appropriate doses.6,7

Segmental thoracic spinal anaesthesia has emerged as an effective alternative to general anaesthesia for breast surgery because it provides excellent surgical anaesthesia, reduces opioid consumption, minimizes postoperative nausea and vomiting, and facilitates enhanced recovery. Imbelloni and Gouveia and van Zundert et al. demonstrated that thoracic spinal anaesthesia can be performed safely with excellent perioperative outcomes when appropriate technique and patient selection are followed.⁴˒⁵

Overall, the findings of the present study suggest that dexmedetomidine is a superior intrathecal adjuvant compared with clonidine for STSA in modified radical mastectomy. It provides prolonged postoperative analgesia, lower pain scores, and reduced rescue analgesic requirements while maintaining acceptable hemodynamic stability and a comparable incidence of adverse effects.

Dexmedetomidine was superior to clonidine as an intrathecal adjuvant to levobupivacaine in segmental thoracic spinal anaesthesia for modified radical mastectomy, providing prolonged postoperative analgesia, better pain control, and improved intraoperative sedation. Both adjuvants maintained satisfactory hemodynamic stability with a comparable incidence of adverse effects. Financial support and sponsorship: Nil Conflicts of interest: There are no conflicts of interest. Acknowledgements: I thank our institution for providing opportunities for conducting this research study and also for providing required equipments. I also thank our staff in our department for their guidance and support. I thank the patients for giving consent and participated in this study.

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