Perforating Cutaneous Nerve Injection Efficacy in Chronic Coccydynia: A Randomized, Double-Blind Study

Effectiveness of Perforating Cutaneous Nerve Injection in Patients With Chronic Coccydynia: A Prospective, Randomized, Placebo-Controlled, Double-Blind Study

Interventions targeting the perforating cutaneous nerve are relatively new to the literature, with a safe side-effect profile but lacking high-quality studies. Their effectiveness remains at the level of case presentations. According to the hypothesis expressed in these publications, coccydynia might be an overlooked cause due to the compression of the perforating cutaneous nerve where it pierces the sacrotuberous ligament and becomes superficial. Ultimately, it is hypothesized that injection of dextrose into this ligament and the sensory area of this nerve will resolve these symptoms due to nerve entrapment, similar to other entrapment neuropathies treated with 5% dextrose, like carpal tunnel syndrome.

Inclusion Criteria:

1. Age between 18 and 50 years.
2. Chronic coccyx pain (≥3 months).
3. Pain Visual Analogue Scale (VAS) score ≥4.
4. Pain not alleviated by first-line treatment (physical therapy/oral analgesic therapy + sitting cushion).

Exclusion Criteria:

1. Injection to the area in the last 3 months.
2. Concurrent mechanical or inflammatory low back pain.
3. Coccyx pain that started during pregnancy or postpartum.
4. History of myelomeningocele or spina bifida.
5. History of sacrococcygeal luxation or subluxation (confirmed by radiography).
6. History of coccyx fracture.
7. Concurrent neurological deficit.
8. Skin disease affecting the injection area.
9. History of malignancy.
10. Pregnancy or breastfeeding.
11. Severe coagulopathy.
12. Infection at the injection site.
13. Neurological or psychiatric diseases, including ongoing depression (Beck Depression Inventory Score >14).