Pudendal Neuralgia Due to Pudendal Nerve Entrapment: Warning Signs Observed in Two Cases and Review of the Literature

Pudendal neuralgia is a chronic neuropathic pelvic pain that is often misdiagnosed andinappropriately treated. The Nantes criteria provide a basis for the diagnosis of pudendalneuralgia due to pudendal nerve entrapment. The 5 essential diagnostic criteria are painsituated in the anatomical territory of the pudendal nerve, worsened by sitting, the patientis not woken at night by the pain, and no objective sensory loss is detected on clinicalexamination. The fifth criterion is a positive pudendal nerve block. We have also clarifieda number of complementary diagnostic criteria and several exclusion criteria that makethe diagnosis unlikely. When pudendal neuralgia due to pudendal nerve entrapmentis diagnosed according to the Nantes criteria, no further investigation is required andmedical or surgical treatment can be proposed. Nevertheless, a number of warning signssuggesting other possible causes of pudendal neuralgia must not be overlooked. Thesewarning signs (red flags) are waking up at night, excessively neuropathic nature of thepain (for example, associated with hypoesthesia), specifically pinpointed pain, whichcan suggest neuroma and pain associated with neurological deficit. In these atypicalpresentations, the diagnosis of pain due to pudendal nerve entrapment should bereconsidered and a radiological examination should be performed. The 2 cases describedin this report (tumor compression of the pudendal nerve) illustrate the need to recognizeatypical pudendal neuralgia and clarify the role of pelvic magnetic resonance imaging(MRI), as MRI provides very valuable information for the evaluation of diseases involvingthe ischiorectal fossa. The presence of red flags must be investigated in all cases ofpudendal neuralgia to avoid missing pudendal neuralgia secondary to a mechanism otherthan nerve entrapment.Key words: Pudendal nerve, pudendal neuralgia, Nantes criteria, pelvic pain, pudendalcanal, perineal pain