625: Case Report: Ulcer and Fistula Formation Following Neurolytic Ganglion Impar Block

Topic: Education, Societal Impact, and Others
Subtopic: Education of pain care

Background and Aims: Introduction
Patients with advanced rectal cancer often experience severe pain inadequately managed by opioids
alone. Ganglion Impar Block (GIB) (Fig. 1) offers an alternative for perineal pain, targeting the
sympathetic innervation of the lower rectum and perineum. While generally safe, GIB carries risks like
infection, visceral perforation, and nerve injury. Neurolytic agents, such as alcohol, provide long
lasting pain relief but can cause complications like nerve necrosis and persistent neuritis (Fig. 2). This
report details a rare complication of ulcer and fistula formation following neurolytic GIB in a metastatic
rectal cancer patient.

Methods: A 44-year-old male with recurrent metastatic rectal cancer presented with severe perianal pain. After a successful diagnostic trial, a neurolytic ganglion impar block using absolute alcohol was performed.

Post-procedure, the patient developed skin necrosis and a foul-smelling ulcer in the gluteal region. Imaging revealed tumor progression, a presacral collection, and a supralevator fistula. The "injection complication" was later linked to a rectal wall defect and abscess extension. Treatment required a repeat low anterior resection (LAR) with ileostomy, antibiotics, and ongoing wound care, resulting in partial improvement by June 2025.

Results: This case details a rare, severe complication following a neurolytic ganglion impar block (GIB) for cancer pain. While the diagnostic block was successful, the subsequent alcohol injection encountered significant resistance due to tumor infiltration.

This resistance likely caused alcohol extravasation into subcutaneous tissues, resulting in gluteal necrosis and fistula formation. The complication was further exacerbated by the patient's existing malignancy and subsequent anastomotic dehiscence. Ultimately, the case emphasizes that anatomical distortions and injection resistance are critical red flags for potential extravasation, necessitating extreme caution during neurolytic procedures.

Conclusions: Conclusion
This report details a rare, severe complication of neurolytic GIB in a patient with metastatic rectal
cancer, involving gluteal ulcer and fistula formation. It emphasizes that tumor infiltration can
significantly increase complication risk, particularly neurolytic agent extravasation. Difficulty during
injection, even with good contrast spread, should be a warning sign for potential compromise of the
injection site and subsequent necrosis. This case highlights the crucial need for extreme caution and
vigilance when performing neurolytic procedures in patients with advanced malignancy and altered
anatomy. Further research is necessary to prevent such unusual complications.

References: References:
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Presenting Author: Mohammad Ghalib Riziq
Submitting Author: Mohammad Riziq

Senior Author: Mohammad Ghalib Riziq

IASP 2026 Global Year theme of Neuropathic Pain: Yes