Both patients underwent surgical repair of rotator cuff with ISB using bupivacaine and epinephrine under general anesthesia.  Case 1. 43 year-old gentleman with bilateral lower extremity weakness five hours after procedure on the right shoulder. Motor exam noted 2/5 in bilateral lower limbs by Medical Research Council strength grading (MRC). Reflexes, sensation, rectal tone were well preserved. MRI of Brain and the entire spine with and without contrast were unremarkable. Case 2. 49 year-old gentleman complained of left hemi body weakness with groin numbness and bladder incontinence after waking up from left shoulder procedure. Examination on left hemi-body is significant for 3-4/5 on MRC, patchy numbness, preserved reflexes and rectal tone. Imaging was not possible due to patient’s body habitus. Both had general anesthesia in the past without issue, no family history of muscle problems or anesthetic complications. Routine blood count, metabolic profile and creatine kinase were unremarkable. One day after symptom onset, both had complete neurological recovery.

Transient neurological sequela as a complication of ISB is a rare phenomenon, but handful of cases were reported in anesthesiology literature. Suggested mechanisms include direct injection into the subarachnoid or epidural spaces or passage of local anesthetic from needle that has punctured a dural cuff surrounding a target nerve. Also there exist reports of permanent neurological dysfunction due to injection of anesthetic into cervical cord. Given the range of possibilities, it is important for the neurologists to be aware of this rare but important complication of Inter Scalene Block.