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A case of motor sparing selective spinal blockade with hyperbaric bupivacaine
during a transurethral resection of the prostate
Spinal anesthetics are commonly used for procedures below the umbilicus, particularly urologic and gynecologic procedures. However, a disadvantage of a spinal anesthetic is the loss of motor function due to nonspecific blockade. Selective Spinal Anesthesia (SSA) is the practice of targeting specific nerve roots supplying a specific area and sensory modality. Clinical trials that have been the most successful in achieving SSA have consisted of a combination of a low dose local anesthetic paired with an intrathecally delivered opiate.
During a medical mission trip to Georgetown, Guyana sponsored by Doctors International and the Guyanese Ministry of Health, the George Washington University Departments of Anesthesiology and and Urology assisted local physicians performing urologic surgeries at Georgetown Public Hospital. During a transurethral resection of the prostate (TURP), an unexpected purely sensory nerve block occurred after intrathecal dosing of spinal bupivacaine.
A 56 year old Guyanese man with significant BPH presented for an elective TURP under spinal anesthesia. The L3-L4 space was approximated using the anatomic landmarks of the spinous processes palpated at the level of the iliac crest with the patient in a sitting position. A BBraun Pencan® Spinal Anesthesia Tray consisting of an iodine based prep, a 20 gauge introducer needle, and a 25 gauge Pencan® pencil point needle was utilized. The spinal needle was used to access the intrathecal space via the introducer, with return of CSF upon stylette removal.
After injection of 1.6 ml of 0.75% bupivacaine with 8.25% dextrose (hyperbaric bupivacaine), the patient was placed in the supine position. Within minutes, the patient developed a sensory block with no pain sensation to noxious stimuli while maintaining full motor strength in his lower extremities. Surgery was completed without complications and afterwards, the patient was able to transfer without assistance from the OR table to the stretcher. He had an uneventful recovery, and the following day had full motor and sensory function.
SSA is challenging to induce and the extent of a neuraxial block is hard to predict. Furthermore, a purely sensory blockade is even harder to generate particularly without the use of intrathecal opiate. One theory that may explain this is the temperature fluctuations that occurred in the transport of the spinal bupivacaine. The spinal kits used in Guyana were transported via airplane, and temperatures can range from 7 -18 °C in the baggage hold.
Additionally, Guyana being an equatorial tropical country had a vastly different temperature profile compared to Washington DC where the kits were acquired. Temperature has been shown to affect the spread of intrathecal bupivacaine when it is warmed or cooled prior to injection, but studies looking at storage and large temperature fluctuation were not found in a preliminary literature search. Further studies in this area may be warranted in understanding how this unique form of SSA can be reproduced.