Pelvic Neurophysiology Testing (PNT) has been in clinical use for over five decades to evaluate neurological causes of pelvic visceral and pelvic floor dysfunction. However PNT is poorly understood by the Urological community and hence not often used in patient assessment. 
PNT is comprised of tests including; Electromyography (EMG) to assess urethral and anal sphincter muscle function, Somatosensory Evoked Potentials (SEP) to assess the S2, S3, and S4 sacral sensory root  function and Bulbocavernosus reflex (BCR) to assess the integrity of sacral sensory and motor roots function. 
This study aimed to evaluate the usefulness of PNT to the Urologist in the assessment of patients presenting with unexplained NOUR. Of particular interest is the role of PNT in predicting success of sacral neuromodulation (SNM) in patients with NOUR.

A retrospective review was conducted on all patients with NOUR who had undergone PNT before SNM by a single surgeon in the U.K. between 2018 and 2023. Clinical evaluations, including neurological examination, video urodynamics (VCMG), and urethral pressure profilometry, were performed.
In addition, women with a presumed diagnosis of Fowler’s syndrome underwent Urethral sphincter EMG. Some patients had an MRI spine. The association between PNT results and SNM outcomes was analysed using statistical tests.

Thirty-four patients (3 male, 31 female), were included in the final analysis, all with NOUR. Median age 32 years (IQR14.75, R: 19-74). Median Follow-up was 2 years (R:0,5- 6 years). See table 1 for VCMG data. Preoperative post-void residual (PVR) was significantly associated with SNM success (p < 0.01).
Of the 34 patients, 29 were diagnosed with Fowler’s syndrome after having diagnostic Urethral sphincter EMG. The remaining 5 patients had NOUR of unexplained aetiology and were therefore investigated with further PNT in an attempt to establish suitability for SNM.
See Table 2 for PNT results of patients with NOUR of unexplained aetiology.
PNT results showed a positive correlation with SNM outcomes in 4 out of 5 cases, highlighting its potential predictive value. 
Of the SNM responders 3/5 had a normal pudendal SEP study.
Of the SNM non- responders 1/5 had an abnormal S2 sacral root study; 1/5 had normal PNT results across the board.

Table 1.VCMG data
	                N(%)	                                               	        Median	           Range
DO	               6(17.6)	                                Capacity(ml)	   576	          286-802
UUI	               2(5.9)	                     Voided volume(ml)	   182	            28-734
SUI                 1(2.9)                                     Qmax(ml/s)	     11	              1-34
Reduced 	3(15)	                  PdetQmax(mmH2O)	    56	            11-650       
compliance		                                   MUCP(cmH20)	   87±21              41-136
		                                           

Table 2.PNP results of patients with NOUR of unexplained aetiology
 Patient	            MRI	    Anal sphincter	   Tibial	   Pudendal	 S2	      S3	     S4    	SNM success
      1	      MOG+TM   	           N	              AB	           N	           -	        -          	-	             +
      2	              neg	                    -	                N	           N	           -            -	         -	             +
      3	              neg	                   N              	N	           N	         AB	        N	        N                   -
      4	              neg	                  AB	                N	           N	           N          N	         -                   +
      5	              neg	                    N	                N                N             N          N             AB	              -
N=normal, AB= abnormal

As Pelvic neurophysiology testing develops and becomes established in urological diagnostic pathways it has the promise to refine patient selection and optimise therapeutic outcomes with SNM. 
Acknowledging the study limitations including its retrospective nature and small sample size; the results indicate 4/5 PNT studies showed a positive correlation in predicting the SNM outcome in patients with NOUR of unknown aetiology.

PNT has the potential to help identify potential SNM responders and also to identify which nerve root should be targeted in the SNM trial, ie S3 or S4. Prospective studies with larger cohorts are warranted to validate these findings.