Two-point deep serratus anterior plane block for modified radical mastectomy - A case series assessing axillary coverage using structured sensory mapping.

Serratus anterior plane block (SAPB) provides chest wall analgesia in modified radical mastectomy (MRM) surgeries by targeting T2-T6 intercostal nerves, but conventional single-injection techniques show inconsistent T2 and axillary coverage, failing to reliably block the intercostobrachial nerve - a key contributor to postoperative axillary pain and postmastectomy pain syndrome. MRM patients experience significant axillary pain from dissection-related intercostobrachial nerve (ICBN) injury, necessitating multimodal analgesia that ensures reliable T2-axillary desensitisation. There is inadequate cephalad/axillary spread in standard SAPB, confirmed by prior studies showing <20% T2 blockade and variable ICBN involvement despite high local anaesthetic volumes. This prospective case series included 10 patients in whom ultrasound-guided deep two-point SAPB was administered with 20 mL of 0.375% ropivacaine at the 5th rib midaxillary line and 10 mL at the 3rd rib anterior axillary line. Sensory mapping via grid, cold/pin-prick Likert scores, and photography 30 min post-block showed reliable T2-T6 dermatomal desensitisation (70% success: composite score >4) confirmed by heat maps. It is concluded that two-point injection at 3rd and 5th rib enhances T2/ICBN blockade over single-level SAPB; nevertheless, larger randomised controlled trials are needed for opioid-sparing validation.