A ganglion impar block (GIB) is an image-guided procedure which can be used to manage refractory perineal and pelvic pain [1, 2]. Gluteal ulcer and fistula formation following a neurolytic GIB with alcohol in a patient with metastatic rectal cancer is an uncommon complication [3-5].
For this patient, the diagnostic GIB provided temporary pain relief, indicating the ganglion's involvement. The difficulty on injection during both procedures suggested tumour infiltration had compromised the anatomical space around the ganglion impar. This is likely to have caused unintended extravasation of the neurolytic alcohol into subcutaneous tissues, leading to necrosis. The existing malignancy and inflammation may have exacerbated this. While direct rectal perforation was not noted, the close proximity, underlying pathology and subsequent anastomotic dehiscence strongly suggest the procedure contributed to the fistula formation.
This case emphasises the need for extreme caution and vigilance when performing neurolytic procedures in patients with advanced malignancy and altered anatomy to prevent severe complications. The difficulty encountered during injection, despite apparent good contrast spread, should serve as a warning sign for possible compromise of the injection site, potentially leading to subcutaneous extravasation and subsequent necrosis [6].
