The data was tabulated in a Microsoft Excel sheet and mentioned as a number (percentage).

Results

The study enrolled 84 patients out of which three patients were removed due to a change in the surgical plan, two patients needed lateral position for subarachnoid block, and general anesthesia was administered in one patient. Therefore, 78 patients successfully completed the study (Figure 3). The demographic profile of all patients are depicted in Table 1. The mean age of the patients was 52.78±8.98 years. The mean weight and height of the patients were 56.13±7.33 kg and 163.71±5.24 centimeters, respectively. However, the mean body mass index was 23.91±0.37 kg/m2 (Table 1).

Figure 3: STROBE flow diagram.

Table 1: Demographic characteristics.

Table 2 states that 89% of patients had a successful sub-arachnoid block with a single attempt of needle insertion. However, in 11% of patients, the operator took two attempts for needle insertion. In addition, 97% of the surgeons were satisfied with the anesthesia technique (Table 2). Initially, two patients had jerky hand movements during the use of electrocautery in the axilla which was corrected with the use of low- current intermittent cautery or dissection with peanuts in the axilla.

Table 2: Surgeon satisfaction and number of attempts.

Table 3 depicts that hypotension was observed in 12 patients and was managed with Inj.  Mephentermine 6 mg IV. Bradycardia was manifested in 6% of the patients and was treated with a single dose of Inj.  Atropine 0.6 mg IV. Inj. Ondansetron 4 mg IV was given to counteract any episode of  nausea or vomiting (Table 3). Two patients complained of respiratory discomfort but they were relieved with reassurance only. Additionally, 4% of the patients had episode of nasal congestion (Table 3). Paresthesia was observed in 4% of the patients upon needle insertion but none of them had similar complaints during drug administration (Table 3).

Table 3: Intraoperative Complications.

The majority of patients (91.02%) were very satisfied with the procedure, were comfortable during surgery and had a quick postoperative recovery (Table 4). A total of seven patients reported average satisfaction, particularly, the patients who experienced nausea, vomiting or respiratory discomfort during the intraoperative period. However, post-dural puncture headache or any difficulty in resuming activity was not encountered by any patient during the postoperative period (Table 4).

Table 4: Patient satisfaction score.

Table 5 depicts the outcome characteristics of the patients. The time taken for full regression of motor and sensory block ranged from 244-283 and 122-154 minutes. Most of the patients (69) were discharged on the third day. The median postoperative stay time in the hospital of the patients was 68 days; however, 66 patients were ambulatory on the same day (Table 5).

Table 5: Outcome Characteristics.

Discussion

Segmental spinal anesthesia remains the most controversial technique amongst anesthesiologists due to the fear of neurological damage because of a puncture at a higher level, ventilation impairment due to the involvement of the diaphragm, and hemodynamic alterations due to the higher block. However, the biggest point of concern is neurological damage while puncturing the dura at a higher level. There are many studies in the literature that showed that the accidental puncture of the dura, even at high thoracic space, does not lead to any neurological damage, which is discussed subsequently. Scherer published his thoracic epidural catheter placement data between T2-T3 and T11-T12 intervertebral spaces in 1071 surgical patients. Primary perforation of dura occurred in 13 patients but none of the patients suffered neurological damage [6]. In 1909, Jonnesco changed the previous trends of the subarachnoid block [7]. It has been more than a century since the puncture of the dura at T1-T2 intervertebral space and he also studied the feasibility of providing analgesia of the head, neck, and upper limbs [7]. Moreover, Jonnesco in their study described two approaches to the thoracic site puncture, one was the higher approach at T1-T2 and the other includes the lower approach at T12-L1 intervertebral space [7]. However, Giebler et al. found that unintentional dural perforation was higher in the lower (3.4%) as compared to the mid (0.9%) or upper (0.4%) thoracic region [8]. The overall incidence occurrence was 1.2% during the thoracic epidural catheter placement in 4185 patients. None of the patients had any neurological damage. They found the incidence of dura perforation in the upper space very less because the approach of the epidural space in a tangential fashion provides a greater margin of safety [8]. The above literature supports our decision to puncture the dura and perform sub arachnoid block at higher thoracic space. Madishetti gave segmental thoracic anesthesia to a patient with bronchiectasis with 1 ml 0.5% Bupivacaine heavy and 20 mcg Fentanyl in T5-T6 Space using the Quincke Babcock needle and the procedure was conducted successfully [9]. Lee et al. measured medial sagittal slices of the thoracic and lumbar region with the help of magnetic resonance imaging in 19 patients. The maximum statistical distance between the posterior dura and cord was found to be more at T6 with 9.5±1.8 mm than at T12 level with 3.7±1.2 mm. They found a greater space at the mid-thoracic level than the lumbar region, sufficient enough for intrathecal drugs. The primary idea behind the choice of T5-T6 space is because in accordance to the literature, it has a maximum distance of 7.75 mm in comparison to T2 space and T10 spaces with 5.18 and 5.88, respectively. As it was noticed that the spinal cord lies anteriorly in the thoracic region and posteriorly in the lumbar region, this space gets more enlarged in the sitting position [10]. Therefore, the sitting position was chosen for the administration of intrathecal block in the present study. Imbelloni et al. researched on magnetic resonance imaging of the thoracic spine and concluded that the maximum distance between the dura mater and the spinal cord is usually at the level of T5-T6 intervertebral space. They observed no statistically significant difference between T2 and T10 levels. However, a statistically significant difference was observed upon comparing the distances at T5 and T2 thoracic levels [11]. The researchers also calculated the distance from the entry point of the needles at an angle of 60% at T5 which would double the distance to obtain cerebrospinal fluid when compared with a 90% angle at L3-4 to 8.64 (2.2) mm. As the distance from the duramater until the spinal cord at T5 is greater than at L1/2, the 60% angle could increase the safety margin [11]. In the present study, we selected the T5-T6 thoracic space for the subarachnoid block as it has the maximum distance between the dura mater and cerebrospinal fluid. Moreover, we kept our needle at an angle of 45° as it gives more distance for the needle tip to travel to the posterior surface of the dura, thereby minimizing the inadvertent chances of cord damage. The speed of injecting the isobaric intrathecal drugs should not be very fast as it causes more cephalad spread. However, this effect is less marked with hyperbaric drugs [12,13]. So, we kept the speed of intrathecal injection relatively slower. In the present study, Quincke Babcock cutting needles for the dural puncture were used. The use of this type of needle is supported by Imbelloni et al. who also preferred a cutting needle over pencil point needle in their study on 300 patients. They illustrated that cutting needles have a terminal hole facilitating the appearance of CSF immediately, whereas in pencil point needles, lateral orifice starts at 0.8 mm and ends only at 1.7 mm. Therefore, there is a need to penetrate 2 mm more in the subarachnoid space for CSF to appear, making it more vulnerable for injury to the underlying structures [14]. Mahmoud et al. performed segmental spinal anesthesia at the T5 level with injection Bupivacaine 5 mg and 0.3 ml Fentanyl in 25 patients undergoing breast surgeries. They observed that the block was found to be satisfactory for patients with minimal hemodynamic instability and no neurological damage [15]. El Moutaz et al. compared segmental spinal thoracic anesthesia with thoracic epidural anesthesia in 35 patients undergoing laparoscopic cholecystectomies. They found that the spinal group had better surgeon satisfaction scores [16]. Vincenzi et al. found thoracic segmental spinal anesthesia at T6-T8 levels in four patients who had undergone unilateral mastectomy ± axillary dissection ± sentinel lymph node biopsy. They concluded it as a safe and effective alternative to general anesthesia [17]. Similar to these findings, we also observed that 97% of surgeons were satisfied with the technique. Hogan et al. studied the size of the human lower thoracic and lumbosacral nerve roots in cadavers. He concluded the facilitation of neural block in the thinner thoracic route was better than thicker lumbosacral route [18]. The CSF content was found to be low in the mid-thoracic region, leading to increased efficacy of epidural local anesthetics at those levels [19]. A low CSF volume and thinner nerve route at the thoracic level lead to an early and dense block in spite the usage of a low volume of local anesthetics in our study. This site-specific subarachnoid block leading to sparing of the lower extremities led to less vasodilatation in comparison to the block at the lumbar level; thus, fewer hemodynamic alterations were reported in the present study [20]. The other advantage was an appreciable patient satisfaction level as there was no motor involvement of the lower extremities [21]. Elakany et al. conducted unilateral mastectomy with axillary dissection under thoracic segmental spinal anesthesia. They compared it with the same number of patients under general anesthesia and concluded that thoracic segmental spinal anesthesia imparted better results [22]. Elakany et al. also observed that patients in the thoracic spinal group spent less time in the hospital and recovery area as compared to the general anesthesia group [22]. In the present study, the median post- operative time in the hospital was 68 hours and most of the patients were discharged on the third day after the operation.

Limitations

One of the limitations of the present study is that our satisfaction score is not the same as proposed by Goth et al. [23]. It would be better if we had taken multiple aspects that govern patient satisfaction scores. Moreover, the study was accomplished on a small group of patients and the results may be more trustworthy if the same study  is conducted on a large set of patients  population.

Conclusions

Segmental spinal anesthesia at T5-T6 level with intrathecal injection of local anesthetic with Dexmedetomidine is a safe and feasible technique for modified radical mastectomies. The technique is particularly helpful in patients with difficult airways and comorbidities. The use of thoracic spinal anesthesia can provide better intraoperative parameters to the satisfaction of surgeons and patients. Although the technique demands a learning curve, the present study recommends its use in routine and highrisk breast cancer patients.

Disclosures

Human subjects: Consent was obtained or waived by all participants in this study. GD Hospital issued approval GDH/2020/019. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

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