Electroneuromyography (ENMG) of the pudendal nerve: what does it demonstrate?
Several instrumental methods are used for precise diagnosis when suspecting pudendal neuralgia. Electroneuromyography (ENMG) is one of the instrumental methods used for precise diagnosis when suspecting pudendal neuralgia. It involves assessing the nerve conduction velocity and signal transmission speed. While the reliability of this method is not absolute, when combined with other diagnostic procedures, it helps determine the localization of pathology.
For
this procedure, highly sophisticated equipment is required, which may not be
available in all clinics. However, we
have the capability to conduct such examinations.
Procedure specifics and result evaluation
Stimulation electroneuromyography involves controlled application of weak electrical impulses to the area under investigation, followed by the recording of the response. It demonstrates:
- Conduction of impulses by nerve fibers.
- Speed of the response.
During the examination, the pudendal nerve is electrically stimulated inside the rectum or vagina at the ischial spine using electrodes attached to the doctor's glove (special fingertip sensors, St. Mark's sensors, are used to increase stimulation accuracy). The nerve signal conduction speed in the needle method is recorded using a small needle inserted into the perineum, or via a surface recording electrode.
The reference values are 2–2.2 milliseconds. If the pudendal nerve responds to the stimulus slower than normal, it indicates that it may be compressed or damaged.
Testing is repeated on both sides of the nerve and usually takes 15-20 minutes. An abnormal response to electrical stimulation suggests a high probability of pudendal neuropathy, but normal readings do not completely rule out the diagnosis. If confirmed, it may indicate that the nerve damage at the time of the examination is not severe enough to be detected. In other words, the individual may have recently developed the condition, and nerve conductivity is only slightly impaired.
Neurological examination can be supplemented with the results of other tests, including measurements of:
- Latency (reaction time) of the anal reflex.
- Latency of the bulbocavernosus reflex.
- Somatosensory evoked potentials of the pudendal nerve.
- Sensory conduction velocity along the dorsal nerve of the penis.
These data can provide additional information about the origin of pain and the condition of the pudendal nerve.
The reliability of the results
The reliability of the results can be ambiguous, so electroneuromyography of the pudendal nerve cannot be considered as the sole diagnostic method. For pelvic pain, a comprehensive approach is necessary. Additional investigations may include:
- Ultrasound of the pudendal arteries: If the artery passing through the same canal as the nerve is narrowed, it is likely that the nerve is also compressed.
- Pharmacological diagnostic blockade of the pudendal nerve: Injection of an anesthetic into the affected area and observation of changes in the patient's sensations.
If the cause of painful sensations lies in pudendal nerve entrapment, a positive response to local anesthesia will be observed, meaning the patient will experience relief. Through a comprehensive approach to determining the source of pain, diagnostic accuracy should approach 100%.
Diagnosing
pudendal nerve entrapment can be challenging due to the lack of unique symptoms
and the often subtle nature of the underlying damage. However, with a
comprehensive approach, including advanced diagnostic techniques, accurate
diagnosis and appropriate management can be achieved.
- Doctor, you said my tomography results were normal, and no pathologies were detected. Could it be that the urologist who referred me to you made a mistake?
- The thing is, pathological changes in ligaments are not always visible. CT and MRI scans are often inconclusive in this case, and a whole range of procedures is used for diagnosis. It's too early to draw conclusions, but we have made some progress. It seems that the doctor referred you for a reason because all the symptoms you have indicate that it could be pudendal neuralgia.
- What should I do now?
- Since there are no signs ruling out the diagnosis except for the questionable tomography result, I will refer you to have an electroneuromyography. It doesn't provide absolute accuracy either, but in combination with other procedures, it can bring clarity.
- Do I need to prepare additionally for it? Is it painful?
- No, it's a minimally invasive procedure and doesn't last long. You may feel some discomfort, but nothing more than that. It's comparable to a regular rectal examination. There's no special preparation required, except perhaps clearing your bowels using an enema if you suffer from constipation.
- Will it be clear how to treat me after this examination?
- Usually, yes. We don't have much time left - soon we will be able to start selecting a therapy for you to use on a regular basis.
Fill out the required questionnaires before your appointment:
Please download, print, and fill out the required questionnaires before your appointment:
1. Questionnaire on the severity of pain syndrome in the pelvic and perineal area.
2. Questionnaire on the quality of life of patients with pelvic organ dysfunction.
3. Comprehensive questionnaire on pelvic organ dysfunction.
