Pudendal entrapment or a tumor?

In the comedy, Kindergarten Cop, Detective John Kimble may only have had a headache, not a tumor, but sometimes our patients do have a tumor. One of my patients was actually just diagnosed with a brain tumor after responding poorly to a cortisone injection for her neck pain. Tumors in other areas of the body, even in the pelvis, can be the source of symptoms that may seem like a nerve entrapment. This is a serious consideration to be given when diagnosing pudendal neuralgia.

In 2008, Labat et al. published the “Diagnostic Criteria for Pudendal Neuralgia by Pudendal Nerve Entrapment” in Neurourology and Urodynamics . A group in Nantes, France, established criteria in 2006, since the diagnosis is primarily clinical in nature. The results of this paper concluded the five essential diagnostic criteria (Nantes criteria) are as follows:

• Pain located in the anatomical region of the pudendal nerve.
• Pain worsened with sitting.
• Pain does NOT awaken the patient at night.
• Negative sensory loss upon clinical exam.
• Pain is relieved with an anesthetic pudendal nerve block.

A recent study by Waxweiler, Dobos, Thill, & Bruyninx explored the Nantes criteria as related to choosing surgical candidates for pudendal neuralgia from nerve entrapment. They looked at how a patient’s response to the anesthetic block corresponded to appropriate selection of patients for a successful surgical outcome. Six of 34 patients in the study had a negative anesthetic pudendal nerve block, and 100% of those patients had no symptom relief after surgery. In contrast, 64% of the patients who met all five of the Nantes criteria responded positively to surgery. The authors concluded confirmation of the 5th criteria as essential for predicting success of surgery for pudendal neuralgia by pudendal nerve entrapment.

In Pain Physician in 2016, Ploteau et al. present two case studies where consideration of the Nantes criteria helped diagnose rare tumors in patients who demonstrated red flags during examination. Warning signs such as nocturnal awakening, point-specific pain, pain of a neuropathic nature, and neurological deficits cannot be overlooked when a patient presents with pudendal neuralgia. In the case studies presented, the 31 year old woman did not have pain exacerbated with sitting and woke at night with pain, and the 62 year old woman was awakened at night with pain. Each patient had magnetic resonance imaging performed, and rare diagnoses of endometrial stromal sarcoma and adenoid cystic carcinoma were made, respectively. The tumors arose in the ischiorectal fossa and compressed the pudendal nerve, presenting as pudendal neuralgia in atypical forms requiring careful clinical examination and referral for MRI for accurate diagnosis.

Although a tumor rarely exists, it is our duty to recognize signs and symptoms that do not follow established criteria. Paying attention to what your patients say just may be lifesaving. Proper diagnosis of pudendal neuralgia is essential and sometimes falls in our hands.

Labat, JJ., Riant, T., Robert, R., Amarenco, G., Lefaucheur, JP., Rigaud, J. (2008). Diagnostic criteria for pudendal neuralgia by pudendal nerve entrapment (Nantes criteria). Neurourology and Urodynamics. 27(4):306-10. doi: 10.1002/nau.20505.
Waxweiler, C., Dobos, S., Thill, V., Bruyninx, L. (2016). Selection criteria for surgical treatment of pudendal neuralgia. Neurourology and Urodynamics. doi:10.1002/nau.22988.
Ploteau, S., Cardaillac, C., Perrouin-Verbe, M. , Riant, T., & Labat, J. (2016). Pudendal Neuralgia Due to Pudendal Nerve Entrapment: Warning Signs Observed in Two Cases and Review of the Literature. Pain Physician. 19:E449-E454.