American Journal of Physical Medicine and Rehabilitation
2009 Mar; 88 (3): S56-57
Patrick M. Foye, MD
Director, Coccyx Pain Service, Department of Physical Medicine and Rehabilitation, UMDNJ: New Jersey Medical School, 90 Bergen St., DOC-3100, Newark, NJ 07103-2499. Phone: (973)972-2802. Fax: (973)972-2825. tailbonedoctor.com/.
BACKGROUND: A 35-year-old female with coccyx pain (coccydynia) presented to the Coccyx Pain Service of a university-based, outpatient, physiatric pain management practice. Her severe coccydynia started acutely during labor and delivery 3 years earlier, while giving birth. Post partum radiographs revealed coccygeal dislocation. The pain became chronic. A subsequent childbirth worsened symptoms. Sitting radiographs showed that the distal coccyx dislocated posteriorly the full width of the coccyx (100% listhesis). Symptoms persisted despite prolonged oral medications (including opioid analgesics), seat cushions, multiple local corticosteroid injections, and a sympathetic nerve block.
INTERVENTION: Next, a diagnostic injection of just 0.5-mL of Lidocaine at the posterior coccyx, under fluoroscopic guidance, relieved 100% of her pain, measured via visual analogue scale (57mm improvement). Based on this excellent response to the transient diagnostic block, she underwent a similarly placed injection of 0.5-mL of 6% aqueous phenol.
RESULTS: At follow-up multiple weeks later she reported that the injection provided a sustained relief of 40% of her pre-injection pain, while functionally she had a four-fold increase in her sitting duration/tolerance. There were no complications.
DISCUSSION: Phenol has been used for chemical neural ablation in treating pain at various body regions. However, to relieve coccydynia previously published reports of phenol ablation have generally focused on destroying the ganglion Impar (the most inferiorly-located of the paravertebral sympathetic nervous system ganglion, located in the retrorectal space, anterior to the coccyx). The case presented here is believed to be the first to describe limiting the phenol ablation to just the somatic nerve fibers at the posterior coccyx. This approach may provide a more superficial (less invasive) way to relieve coccydynia, in appropriately selected patients, identified via diagnostic block. These nerves are also accessible for radiofrequency ablation. These procedures can be repeated if needed. These injections may provide patients with additional non-surgical treatments for coccydynia.