Introduction of Pelvic electrophysiologic test: BCRL, Pudendal SEP, PNTML

1. Pelvic Electrophysiology Tests
- practical applications and limitations
Jongkyu Kim

2. Today’s talk
Muscular and neuro-anatomy of pelvic electrophysiologic tests
(pudendal nerve tests)
Bulbocavernous reflex latency (BCRL)
Pudendal nerve SEP
Pudendal nerve sensory NCS
EMG
Pudendal nerve terminal motor latency (PNTML)
My clinical application
16 May 2023
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3. Ice breaking
16 May 2023
3 https://www.bbc.co.uk/bbcthree/article/68c9c99d-c9d8-4857-96dd-b10336e2118e
https://www.irishnews.com/magazine/daily/2019/04/30/news/why-people-in-korea-are-talking-about-leeds-united-without-even-knowing-it-1609389/

4. Leeds season/era “리즈시절”, “lijeu sijeol”
• “Doing a Leeds” means potentially
dire consequences for domestic
clubs in financial mismanagement.
• But, Leeds season/Leeds era in
Korea means “a person’s prime or
golden age” or “the most
successful days of a person’s past
life”
• “You look exactly the same as your
Leeds era” means “Your
appearance is very excellent as
your young age”
• “The movie Romeo+Juliet showed
his Leeds era of Leonardo DiCaprio”
• “Anya Taylor-Joy renewed her
Leeds era in the new movie”
16 May 2023
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5. • Ji-sung Park joined Manchester United, became the 1st
Korean EPL player in 2005
• Korean broadcasters started EPL coverage.
• Alan Smith was an attacker of Leeds United, pulled off
outstanding performances
• Leeds United was relegated and Alan Smith moved to
Manchester United
• At Manchester, He was marred with controversies and
injuries
• Some Korean fans began to compare his performance at
Manchester and Leeds in online spaces, “Alan Smith was
outstanding at his Leeds United era, but not now”
• From that time, “Leeds era” is used more commonly
outside football
• Nowadays, the phrase is used for compliment to
someone’s beauty/appearance
16 May 2023
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6. Three nerves
associated neurogenic bladder
• Hypogastric nerve
• T12-L2
• Sympathetic
• Inhibit detrusor contraction
• Pelvic nerve
• S2-4
• Parasympathetic
• Unopposed impulse to detrusor contraction
• Pudendal nerve
• Somatic motor
• Innervates pelvic floor muscles and external
sphincter
• Voluntary voiding control
• Detrusor function test – Urodynamic study
• Pudendal nerve function test?
16 May 2023
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7. Various pudendal nerve tests
• Nerve test for long tract
• Bulbocavernosus Reflex Latency (BCRL)
• Pudendal SEP
• Nerve test for short/distal segment
• Pudendal sensory nerve conduction study
• Pudendal nerve terminal motor latency (PNTML)
• EMG
• External anal sphincter (EAS) EMG
• Bulbocavernosus muscle (BCM) EMG
16 May 2023
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8. Bulbocavernous Reflex
• Bors and Blinn (1959) first used for
examination of the neurogenic bladder
• Rushworth (1967) obtained BCR by
neurophysiology recording from BC
muscle
• Squeeze glans penis or clitoris or retract
pubic hair
• Then, feel constriction of external anal
sphincter
• Synapse on S2-S4 sacral nucleus to
contralateral side
16 May 2023
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from https://epomedicine.com/clinical-medicine/bulbocavernosus-reflex/
Granata, G. et al. Electrophysiological study of the bulbocavernosus reflex: normative data.
Funct Neurol 28, 293–5 (2013).

9. BCR
• Manifestation of spinal shock
• Cauda equina lesion
• Erectile dysfunction
• Various other neurologic
disorders – multiple sclerosis,
multiple systemic atrophy, etc
• Using intra-operative monitoring
when surgery on sacral spinal
cord area
16 May 2023
9 from https://youtu.be/jMYsMxZjZwQ?t=7

10. Bulbocavernosus muscles
• Bulbocavernosus
(bulbospongiosus) +
ischiocavernosus muscles
• Innervated by pudendal motor
nerves (perineal nerve to BCM)
• Contribute to penile/clitoral
erection & orgasm
16 May 2023
10 from https://en.wikipedia.org/wiki/Transverse_perineal_muscles

11. BCR
• Oligosynaptic spinal reflex
• Sacral arc of S2 to S4 (S1 to S5 in
some reports)
• Crossing synapses, the number of
synapses are unknown
• Afferent: dorsal nerve of
penis/clitoris, branch of pudendal
sensory nerve
• Efferent: deep branch of perineal
nerve, branch of pudendal motor
nerve
16 May 2023
11 from Yang, C. C. & Bradley, W. E. Reflex innervation of the bulbocavernosus muscle. Bju Int 85, 857–863
(2000)

12. Complex oligosynaptic reflex pathway
• Recent neuroanatomy
• Both ipsilateral and
contralateral synapses
• Difference between
dorsal and ventrolateral
branches
• Presence of recurrent
reflex
→Various responses
→Limitation of EDx
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13. Simple motor nerve conduction study
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14. Monosynaptic reflex
Deep tendon reflex and H-reflex
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15. Complex oligosynaptic reflex pathway
• Oligosynaptic reflex
→Various responses
→Limitation of Edx
→The waveform is not
clear
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16. 16 May 2023
16
from Malladi, P., Simeoni, S. & Panicker, J. N. The Role of Pelvic Neurophysiology Testing in the Assessment of
Patients with Voiding Dysfunction. Curr Bladder Dysfunct Reports 15, 229–239 (2020)
Kothbauer, K. F. & Novak, K. Intraoperative monitoring for tethered cord surgery: an update. Neurosurg Focus
16, E8 (2004)

17. Bulbocavernosus Reflex Latency (BCRL)
• Stimulate dorsal nerve of penis at
glans penis using ring
electrode/clitoris using bar
electrode
• Recording from bulbocavernosus
muscle using needle electrode
• Originally concentric needle electrode
• Can replace with monopolar needle
electrode
• 10 to 20 sweeps superimposed
• Latency (msec) 36.1 ± 4.6
16 May 2023
17 JA Liveson, DM Ma. Laboratory Reference for Clinical Neurophysiology. UK: Oxford University Press, 1992.

18. Clinical hurdles of BCRL
• Privacy and patient’s discomfort
• Must show off genitalia
• Direct electrical stimulation to
penis/clitoris
• Needle insertion to BCM
• Concentric needle is relatively thick
• To find BCM, deep palpation of pelvic
floor is essential
• Technical difficulty
• Finding BCM needs learning curve
• By palpation and needle EMG signal
• EAS vs BCM
• When EAS, we can use surface or
sponge electrode, not needle
• But, EAS has resting contraction tone,
making noise signal
• If resting is possible on EAS, it may
reflect dysfunction of pudendal
motor nerve
• BCM located relatively deep space
• Surface electrodes show limitation
• But, resting and voluntary contraction
are possible
16 May 2023
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19. External Anal Sphincter EMG
• Normally shows continuous
muscle tones even when resting
• Cannot distinguish denervation
potentials from motor unit
action potential
• Sometimes used at ano-rectal
physiology lab
16 May 2023
19 Electrodiagnostic Medicine. UK: Hanley & Belfus, 2002.
From Medscape

20. Pudendal SEP
• Same stimulation site with BCRL
• Dorsal nerve of penis/clitoris
• Recording from scalp, neck, lower
back
• P1 latency (msec) 42.3 ± 1.9 in
male, 39.8 ± 1.3 in female (scalp
recording)
• Pudendal sensory nerve – dorsal
column-medial lemniscus pathway
16 May 2023
20 from https://youtu.be/fnpSz8NaZSA

21. SEP – dorsal column pathway evaluation
• Larger fibres shows faster and
larger action potentials
• Small action potentials are filtered
by machine
• Most important parameter is
latency, which is determined by the
fastest fibres
• Thus, SEP reflects only dorsal
column (not whole nerve)
16 May 2023
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22. Pudendal sensory nerve conduction
• Stimulate glans penis
• Record from dorsum of penis
• Only distal short segment of
dorsal nerve of penis
• Only possible in male
• The nerve running is tortuous,
so extender is needed to find
velocity
• Sexual function evaluation
16 May 2023
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23. Pudendal nerve terminal motor latency
(PNTML)
• Stimulate distal pudendal motor
nerve inside the rectum
• Record from EAS
• Using special device – St Mark
pudendal electrode
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24. • Specially designed for PNTML
• Rectal preparation (enema)
• Palpate ischial spine inside the
rectum by index finger –
stimulation point
• Feel the EAS constriction
• Onset latency less than 2.4 msec
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Stimulating
electrode
Recording
electrodes
St Mark pudendal electrode

25. PNTML
• Only latency is meaningful
• Used ano-rectal physiology lab to
distinguish neurogenic faecal
incontinence
• Can be used for bowel incontinence in
CES patients – can be replaced with
anorectal manometry
• Only very short, distal segment of
perineal nerve to EAS
• Cannot calculate conduction velocity
because the nerve doesn’t run straight
• Simple, very non-invasive, quick, but it
needs rectal preparation
16 May 2023
25 from my archives

26. My clinical experiences - BCRL
• Started independent study from 2007 during my residency
• Patients with cauda equina injury
• We included BCRL and pudendal SEP as baseline studies for CES patients
• At 2000 to 2010, the legal proceeding about traffic accidents, industrial accidents,
and medico-legal problems needed evidence of SCI or CES, including Edx evidences
• Nowadays, the courts do not want Edx evidence for SCI/CES any more, thus the
number of exams decreased. UDS is sufficient.
• Some patients with erectile dysfunction
• Referred from urology
• Recently, replaced to Nocturnal Penile Tumescence (NPT) test
16 May 2023
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27. Overcome learning curve
• Finding BCM and needle
placement need learning curve
• No specific surface anatomy
• Various depth of each individual
• Less cases: teaching is difficult
• My tip
• Deep palpation of BCM with
monitoring EMG responses
• Pelvic floor ultrasound
• Trans-perineal US?
16 May 2023
27 Hainsworth, A. J., Solanki, D., Schizas, A. M. P. & Williams, A. B. Total pelvic floor ultrasound for pelvic floor
defaecatory dysfunction: a pictorial review. Br J Radiology 88, 20150494 (2015).

28. Clinical applications of BCRL
• No usage in suprasacral SCI
• In CES or conus medullaris
injured patients
• When BCRL is absent?
• When BCRL is intact?
• When BCRL is delayed?
• When ipsilateral BCRL is intact and
other side is delayed?
• Will be helpful for prognosis?
• Can UDS replace BCRL?
• In general, maybe!
• In some incomplete CES, BCRL is
essential.
• In conclusion,
• Nowadays, BCRL is not essential
for neurogenic bladder of CES
• In some incomplete CES, or vague
neurogenic bladder patients, it will
be helpful
16 May 2023
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29. PNTML
• No usage in neurogenic bladder
evaluation
• Proper exam for neurogenic
faecal incontinence
• Simple and easy to learn
• Less time, less invasiveness,
even if rectal preparation
• Only very short segment, most
distal part of perineal nerve to
EAS
• Only latency, cannot obtain
velocity – less accurate study for
neuropathy
16 May 2023
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30. 16 May 2023
30 Malladi, P., Simeoni, S. & Panicker, J. N. The Role of Pelvic Neurophysiology Testing in the Assessment of Patients
with Voiding Dysfunction. Curr Bladder Dysfunct Reports 15, 229–239 (2020).

31. Thank you
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32. My next talks…
4 July 2023
Next topic is…
Cancer rehabilitation in South Korea: status quo
Do you want to any specific detail about this topic?
Please let me know
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