2026, Number 2
Computed tomography-guided analgesic block as a therapeutic option in pudendal nerve neuralgia
Full text
10.35366/122628
Language: English/Spanish [Versión en español]
References: 5
Page: 168-171
PDF size: 1610.03 Kb.
ABSTRACT
Introduction: it's suggested to use Nantes criteria, image and neurophysiology studies to rule out differential diagnoses. Clinical case: 25-year-old female, lumbar pain, radiating to right gluteal and dyspareunia. Three of the five Nantes criteria were integrated and no response to conservative treatment. Electromyography reports demyelinating sensory neuropathy of the right pudendal nerve. An analgesic block of the pudendal nerve guided by tomography was made. Results: follow-up after two and four months showed 90% improvement, decreased pain, no dyspareunia, VAS 2 of 10 and ODI 10%. Conclusions: diagnostic suspicion is crucial for the timely management of pudendal nerve neuralgia.INTRODUCTION
Pudendal nerve neuralgia remains a diagnostic challenge, given that its etiology is unknown and it often goes unnoticed on multiple occasions. According to the International Pudendal Neuropathy Foundation, the incidence is estimated to be 1 per 100,000, affecting 1% of the general population and 4% of patients presenting with pelvic pain in consultation, with a 2:1 female-to-male ratio.1
The pudendal nerve originates from the ventral rami of the S2-S4 spinal roots and is responsible for the innervation of the perineal muscles and genital area structures.2 After originating from the sacral roots, the pudendal nerve follows a characteristic path. It initially heads toward the piriformis foramen, hooks around the sacrospinous ligament, and enters the pelvis through the lesser sciatic foramen. It advances toward the ischioanal fossa and, before reaching the ischial tuberosity, runs through Alcock's canal, from where it finally divides into its terminal branches toward the perineal region.3
Pudendal nerve neuralgia, primarily caused by entrapment along its course, results in urinary, gastrointestinal, and/or genital alterations that can vary from pain to dysfunction of these systems.4 Entrapment zones can be subdivided into four types: 1. Distal to the piriformis muscle, 2. Between the sacrotuberous and sacrospinous ligaments, 3. Alcock's canal, and 4. At the level of the terminal branches.5
In addition to entrapment zones, pudendal nerve neuralgia can be caused by cumulative microtrauma such as chronic constipation, birth canal injuries, prolonged sitting, sports activities, or direct trauma.
It is fundamentally a clinical diagnosis, for which the application of the Nantes criteria is recommended (Tabla 1).
One of the major limitations is the lack of a specific diagnostic imaging or laboratory study; even so, complementary studies such as X-rays, magnetic resonance imaging, and computed tomography must be performed to rule out differential diagnoses.
The neurophysiological approach is useful for diagnosis, especially somatosensory evoked potentials or the pudendal nerve terminal motor latency, which can confirm the diagnosis.
Treatment must be established through a multidisciplinary approach and begins with psychosocial support, auxiliary measures based on limiting the compressive stimulus of the nerve, the use of a cushion for sitting, the use of a standing workstation, as well as the cessation of hip flexion and extension exercises, and using variants of selective serotonin-norepinephrine reuptake inhibitors and neuromodulators. When pharmacological treatment is ineffective, a pudendal nerve block is chosen, and when the latter proves effective, it confirms the diagnosis.
CLINICAL CASE
A 25-year-old female patient presented after a car accident with progressive lower back pain, 8/10 on the visual analog scale, 60% on the Oswestry Disability Index (ODI), radiation to the right gluteal area, and dyspareunia, evolving into disabling pain upon sitting, with improvement only when lying down.
Three of the five Nantes criteria were integrated: pain worsened by sitting, pain does not awaken the patient from sleep, and no specific sensory loss is reported.
The patient was treated for three months with pelvic floor therapy, nonsteroidal anti-inflammatory drugs, avoidance of prolonged sitting, use of a gluteal cushion, and physical rehabilitation, without showing a favorable response.
A magnetic resonance imaging study was performed, which revealed disc degeneration and protrusion at the L4-L5 level, as well as a 1 mm right facet hydrarthrosis. In order to rule out nerve compression, the diagnostic protocol was continued using tractography, which showed no signs of compression along the course of the nerve; however, it showed findings suggestive of neuritis and pelvic congestion (Figure 1).
Subsequently, an electromyography was performed, which reported demyelinating sensory neuropathy of the right pudendal nerve. With these findings, the diagnosis of pudendal nerve neuralgia was integrated.
DESCRIPTION OF SURGICAL TREATMENT
A tomography-guided analgesic pudendal nerve block was proposed. Grid marking was performed under tomography guidance, using the ischial spine and the gluteal area as references; a spinal needle was inserted, and its location was confirmed using contrast medium (Figure 2).
A pharmacological combination of 40 mg of methylprednisolone acetate, ropivacaine, and 0.9% saline solution was administered.
RESULTS
Following the pharmacological block, the patient reported a 90% improvement in pain, providing solid evidence supporting the diagnosis of pudendal nerve neuralgia and the efficacy of the treatment. At the two- and four-month follow-ups, the patient continued to show significant and sustained improvements, reporting decreased pain and absence of dyspareunia, the ability to perform daily activities without pain, a visual analog scale score of 2/10 only during impact activities, and an ODI of 10%.
DISCUSSION
The diagnosis of pudendal nerve neuralgia can easily go unnoticed, meaning the clinician must conduct an interview and physical examination based on the triggering symptoms.
It is important to document findings based on the Nantes criteria, exclude a compressive cause, and perform the nerve block as part of the diagnostic-therapeutic algorithm when first-line therapeutic measures have failed.
It was decided to use a tomography-guided pudendal nerve block, considered the most accurate technique for the direct delivery of the medication, using a corticosteroid plus a local anesthetic, which achieved an improvement of greater than 90% in symptoms.
Treatment is multimodal, including pelvic floor physical therapy, antineuritic medication, and/or pudendal nerve blocks, which can be performed every two months before considering a spinal cord stimulator as an alternative.
CONCLUSION
It is important to maintain a high level of clinical suspicion to support the diagnosis of pudendal nerve neuralgia, as well as to perform a differential diagnosis to initiate treatment properly, prioritizing pain management and improving quality of life.
REFERENCES
AFFILIATIONS
1 Hospital Angeles México. México.
2 Traumatología y Ortopedia, Cirugía de Columna. ORCID: 0009-0000-0909-7476
3 Medicina General e Investigación. ORCID: 0009-0009-4931-2041
4 Neurocirugía y Cirugía de Columna. ORCID: 0009-0005-0758-0911
5 Neurocirugía y Cirugía de Columna. ORCID: 0009-0005-2350-8565
6 Neurocirugía y Cirugía de Columna. ORCID: 0009-0000-6553-6840
7 Anestesia y Medicina del Dolor. ORCID: 0009-0008-0519-3354
8 Radiología Intervencionista e Imagen. ORCID: 0009-0008-6422-0199
9 Radiología Intervencionista e Imagen. ORCID: 0000-0002-1540-154X
10 Neurocirugía y Cirugía de Columna. ORCID: 0000-0001-8641-2150
If you wish to consult the supplementary data for this article, please contact editorial.actamedica@saludangeles.mx
CORRESPONDENCE
MC. Diana Chávez Lizárraga. Correo electrónico: diancha@gmail.comReceived: 2025-11-25. Accepted: 2026-02-02.