Prospective comparative study of abnormal distal rectoanal excitatory reflex, pudendal nerve terminal motor latency, and single fiber density as markers of pudendal neuropathy.
OBJECTIVE
This study was undertaken to determine the role of abnormal distal rectoanal excitatory reflex (RAER) as a marker of pudendal neuropathy and to compare results with pudendal nerve terminal motor latency (PNTML) and single fiber density (SFD) estimation.


METHODS
Fifteen female patients (mean age, 47.1 (range, 20-70) years) referred to the pelvic floor laboratory with pelvic floor disorders (fecal incontinence, 13 patients; constipation, 2 patients) were evaluated prospectively with neurophysiologic tests and balloon reflex manometry for evidence of pudendal neuropathy.


RESULTS
Pudendal nerve terminal motor latency provided evidence of pudendal neuropathy in ten patients (67 percent) and was normal in five patients (33 percent). Increased SFD confirmed denervation of the external anal sphincter in 12 patients (80 percent), being normal in 3 patients (20 percent). Distal RAER was abnormal in 13 patients (87 percent) and was normal in 2 patients (13 percent). In ten patients (67 percent), the three diagnostic modalities were in complete agreement, correctly identifying neuropathy in nine patients (60 percent) and excluding nerve damage in one patient (7 percent). Distal RAER was normal despite prolonged PNTML and increased SFD in one patient (7 percent). In two patients (13 percent), distal RAER was abnormal or absent despite normal PNTML and SFD. Pudendal nerve terminal motor latency was normal in the presence of abnormal distal RAER and increased SFD on electromyography in two patients (13 percent).


CONCLUSIONS
Abnormal distal RAER compares favorably with current neurophysiologic tests used to diagnose pudendal neuropathy.
Sangwan
Y P
YP
Department of Colon and Rectal Surgery, Lahey Hitchcock Medical Center, Burlington, Massachusetts 01805, USA.
Coller
J A
JA
Barrett
R C
RC
Murray
J J
JJ
Roberts
P L
PL
Schoetz
D J
DJ
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008365:Manometry; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D009412:Nerve Fibers / Q000502:physiology*; D017773:Pelvic Floor / Q000294:innervation*; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000503:physiopathology*; D011446:Prospective Studies; D012021:Reflex, Abnormal / Q000502:physiology*