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Nantes Criteria

 

Further details, mainly for medial professionals, on the Nantes Criteria for diagnosis of Pudendal Neuralgia:

1 Pain in the anatomical territory of the pudendal nerve from anus to the penis or clitoris:

The pain must be situated in the territory of the pudendal nerve, which extends between the anus and the clitoris or penis. Pain may be superficial or may be situated slightly deeper in the anorectal region, vulvovaginal region and distal urethra.

2 Worsened by sitting:

This is an essential clinical feature providing evidence in favor of the hypothesis of nerve compression in the context of an entrapment syndrome. Any loss of mobility of the nerve (regardless of its site) is therefore associated with a risk of compression against rigid ligamentous structures such as the ligamentous attachments to the ischial spine, these being the commonest site of entrapment, the other common point being in Alcock's canal where the nerve runs round the inner side of the ischial tuberosity. Very often, pain is initially experienced only in the sitting position, but with time pain tends to become much more continuous even if it is still predominantly experienced while sitting.  Often, patients will comment that they are more comfortable sitting on a ring structure such as a toilet seat.

3 The patient is not woken at night by the pain

Many patients experience pain at bedtime and may have difficulties going to sleep. Although they can be woken by associated symptoms (e.g., need to urinate), they are never woken by perineal pain. Patients only exceptionally report a history of waking due to pain at night, but these episodes are only transient.

4 No objective sensory loss on clinical examination

This is an essential clinical finding. The presence of a superficial perineal sensory deficit is highly suggestive of a sacral nerve root lesion, particularly involving the cauda equina nerve roots, or a sacral plexus lesion. These proximal lesions usually do not cause pain and present clinically with sensorimotor deficits, especially sensory loss and sphincter motor disorders. Several hypotheses can be proposed to explain this absence of objective sensory impairment. The compression may be insufficient to induce a lesion of the fibers of superficial sensation, as observed in the case of sciatica and many cases of carpal tunnel syndrome.

5 Positive anesthetic pudendal nerve block

Anesthetic infiltration of the pudendal nerve significantly relieves pain for the duration of local anesthesia. This is an essential criterion, but is not specific as it simply indicates that the pain is situated in the territory of the pudendal nerve; pain related to any perineal disease (e.g., anal) would also be relieved by pudendal nerve block and other types of nerve lesions would also have a positive diagnostic block when they are situated distal to the site of infiltration. A negative block does not formally exclude the diagnosis when it is not performed with sufficient precision or when it is performed too distally (e.g., in the pudendal canal, while the pudendal nerve lesion may be situated at the ischial spine).
Other clinical criteria can provide additional arguments in favor of the diagnosis of pudendal neuralgia.

Complementary diagnostic criteria:

  • Burning, Shooting, Stabbing Pain, Numbness: Pudendal neuralgia presents the characteristics of neuropathic pain, which is described as burning, shooting, stabbing or aching pain and numbness
  • Allodynia or hyperpathia, highly suggestive of neuropathic pain.  This corresponds, in the pudendal nerve territory, to intolerance of tight clothes and underwear (boxer shorts are preferred to briefs), and intolerance of vulval contact with superficial dyspareunia
  • Rectal or vaginal foreign body sensation: patients generally use fairly vivid terms to describe their deep pain, generally situated in the anus and rectum or sometimes in the vagina or urethra. They frequently describe a feeling of "foreign body," but other expressions are also suggestive: feeling of a stake, a lump, heaviness, a tennis ball, a gnawing, or crawling feeling.
  • Worsening of pain during the day: Absence of pain in the morning on waking, slight pain in the morning, deterioration during the day reaching a peak in the evening until the patient goes to sleep is a very characteristic temporal profile of pudendal neuralgia.
  • Predominantly unilateral pain: Perineal pain is particularly suggestive of a pudendal nerve trunk lesion when it is unilateral (and when it is experienced in all of the anterior and posterior hemiperineum), but midline or central pain does not exclude the diagnosis.
  • Pain triggered by defaecation: This is a feature of predominantly posterior pain; pain is not experienced immediately after defecation, but generally several minutes to one hour later.
  • Palpation of the ischial spine (posterior and slightly lateral) during digital rectal or vaginal examination is very often tender.

Associated signs not excluding the diagnosis

The symptoms of pudendal neuralgia may be strictly limited to the diagnostic criteria defined above, but many patients present associated, polymorphic and perplexing symptoms that are often difficult to attribute to the pudendal nerve.

  • Buttock pain on sitting: Gluteal innervation is not dependent on the pudendal nerve and isolated buttock pain, even occurring while sitting, cannot be considered to be due to pudendal neuralgia. However, the combination of perineal neuralgia and buttock pain can be explained by a common, fairly proximal conflict underneath the piriformis muscle with a concomitant lesion of the posterior femoral cutaneous nerve or inferior gluteal nerve.
  • Suprapubic pain: Suprapubic pain can be due to hypertonia of the puborectalis component of the levator ani muscles. Bone tenderness may suggest a complex secondary pelvic pain syndrome
  • Urinary frequency and/or pain on a full bladder: Urinary frequency is often associated with pudendal neuralgia and tends to evolve intermittently, in parallel with the pain, allowing it to be attributed to pudendal neuralgia rather than to bladder dysfunction. There are probably synaptic interconnections associated with inappropriate processing of nociceptive messages resulting in transmission of false urges. Patients sometimes report urethral or hypogastric pain worsened by bladder filling and relieved by voiding.
  • Pain occurring after ejaculation: This isolated symptom, which is perplexing in the absence of infection (absence of seminal vesiculitis), cannot be attributed to pudendal nerve entrapment syndrome.
  • Dyspareunia and/or pain after sexual intercourse: The frequency of sexual intercourse is often reduced in the context of pudendal neuralgia, essentially because chronic pain decreases libido. Sexual intercourse is rarely very painful, but pain can be experienced in the case of vulval allodynia, but patients generally do not report pain during intercourse, but worsening of pain over the hours following intercourse.
  • Erectile dysfunction: Pudendal neuralgia, affecting a somatic nerve, is only partially involved in erection. Classically, the main sexual function of the pudendal nerve is sensory (dorsal nerve of the penis and dorsal nerve of the clitoris), but it is also involved in pre-ejaculatory hyperrigidity and in the clonic nature of ejaculation. Patients with pudendal neuralgia Frequently complain of a feeling of penile numbness, decreased sexual sensations or even decreased penile rigidity.
  • Normal clinical neurophysiology: Electrophysiological studies (electromyography and nerve conduction studies) only investigate large motor fibers andmay not detect selective lesions of small sensory fibers. Furthermore, due to the postural nature of the pain, a neurological lesion may not always be present in the context of intermittent conflict.
  • Exclusion criteria:

  • Purely coccygeal, gluteal, or hypogastric pain
  • Exclusively paroxysmal pain
  • Exclusive pruritus
  • Presence of imaging abnormalities able to explain the symptoms
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    Page updated 15/02/2016