Parasacral ischial plane block: a new analgesic option for lower limb surgery

A novel fascial plane approach to the sacral plexus is the parasacral ischial plane (PIP) block. It is a comparatively simple approach that doesn't call for sacral plexus visualisation. It is safe to use on individuals who have lost a limb since neuromuscular stimulation is less effective in such cases. For below-knee operations, a recently reported case series of diabetic wound debridement procedures performed under PIP block offered sufficient sensory analgesia.

In this prospective case study, ten American Society of Anesthesiologists physical status II–IV patients, ages 18–70, who were scheduled for elective lower limb debridement procedures, were included. The block took around 4 minutes to complete in each example. It took 9 to 15 minutes for complete sensory loss. Till 30 minutes following the investigator's observation, none of the patients had a total motor blockage. None of the patients needed additional analgesics during surgery. This block is simple to do technically, takes less time, and provides sufficient sensory analgesia for below-knee procedures.

A fascial plane produced by several tissues contains the sacral plexus. The pelvic fascia surrounds it from the front, the sacrum bone from the side, the ischium from the side, and the piriformis muscle from the back. Between the ischial bone and the piriformis muscle, there is a fascial plane that runs laterally to the sacral plexus. The sacral plexus is directly connected to this plane. Any medicine injected into the space between the ischium and piriformis will thus go to the sacral plexus.

The PIP block has a number of advantages. PIP is a fascial plane block, therefore precise needle tip positioning is not necessary. The distance between the needle tip and the brain structures prevents neurovascular injury. Bony structures are clearly visible on US, especially in individuals with tissue oedema or obesity, in contrast to neuronal components. As a result, it is a simple treatment with a high chance of success. PIP block may be routinely used in patients with above- or below-knee amputations when neuromuscular stimulation is less beneficial.

Reference –

Sherfudeen, Khaja Mohideen; Sankarlal, Nirmal Kumar; Jayapal, Indupriyadarshini; Kaliannan, Senthil Kumar. Parasacral ischial plane block for lower limb wound debridement surgeries – A case series. Indian Journal of Anaesthesia 66(12):p 861-864, December 2022. | DOI: 10.4103/ija.ija_485_22