Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
-
Upload
puntocom111 -
Category
Documents
-
view
220 -
download
0
Transcript of Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
1/32
Nerve Adaptation in Response to
Mechanical Loading
Marko Bodor MD
Physical Medicine and Rehabilitation,
Spine and Sports MedicineNapa, California
Voluntary Assistant Professor
Departments of Neurological Surgery
University of California San FranciscoPhysical Medicine and Rehabilitation
University of California Davis
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
2/32
Disclosure
No disclosures relative to the current
presentation.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
3/32
Skin
Skin adapts to mechanical loading by
getting thicker .
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
4/32
Muscle
Muscles adapt to mechanical loading by
getting larger.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
5/32
Bone
Bones adapt to mechanical loading by
increasing in thickness and diameter.
From Ireland A et al
Med Sci Sports 2013
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
6/32
Nerve
Do nerves adapt to mechanical loading?
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
7/32
Tires
How is it that a 2000 kg car has tires that
need only 2.5 ATM pressure while those of
an 80 kg bicycle/rider require 5 ATM?
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
8/32
Larger
tires
allow
lower
tire
pressures.
1) 2.5 ATM ≈ 2.5 kg force/cm2.
2) Contact area = 20 x 25 cm
= 500 cm2.
3) 2.5kg/cm2 x 500 cm2 =1250 kg.
4) 4 tires x 1250 kg/tire = 5000
kg support for the car.
1) 5 ATM ≈ 5 kg force/cm2
2) Contact area = 3 x 5 cm =
15 cm2.
3) 5 kg/cm2 x 15 cm2 = 75kg.
4) 2 tires x 75 kg/tire = 150
kg support for bike & rider
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
9/32
Tire‐Nerve Analogy
Larger nerves will have lower intraneural
pressure for the same externally applied load.
100 gm load on a 5 mm2 nerve = 20 gm/mm2 ≈ 200 kPa
100 gm load on a 10 mm2 nerve = 10 gm/mm2 ≈ 100 kPa
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
10/32
Evidence
for
Nerve
Enlargement
#1
Gitlin G Concerning the gangliform enlargement
(pseudoganglion) on the nerve to the teres minor
muscle. J Anat 1957.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
11/32
Nerve
enlargement
observed
in
26/36normal cadavers at quadrangular space
Gitlin G Concerning the gangliform enlargement
(pseudoganglion) on the nerve to the teres minor
muscle. J Anat 1957.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
12/32
Evidence
for
Nerve
Enlargement
#2
Neary D, Ochoa J, Gilliat RW. Subclinical
entrapment neuropathy in man. J Neurol Sci 1975
P6
ME
D4
Ulnar nerve
enlargement
seen at medial
epicondyle (ME)
in 12/12cadavers:
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
13/32
Evidence
for
Nerve
Enlargement
#2
Neary D, Ochoa J, Gilliat RW. Subclinical
entrapment neuropathy in man. J Neurol Sci 1975
P6
ME
D4
7/12 – no
pathologicchanges
5/12 – bulbous
swellings and
intercalated
segments.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
14/32
Evidence
for
Nerve
Enlargement
#3
Neary D, Ochoa J, Gilliat RW. Subclinical
entrapment neuropathy in man. J Neurol Sci 1975
P6
ME
D4
Median nerve
enlargementseen at flexor
retinaculum in
12/12 cadavers:
Renaut bodies ( RB )
seen in all nerves at
level of retinaculum
RB
RBRB
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
15/32
Evidence
for
Nerve
Enlargement
#3
Neary D, Ochoa J, Gilliat RW. Subclinical
entrapment neuropathy in man. J Neurol Sci 1975
P6
ME
D4
7/12 - no
pathologicchanges
5/12 – bulbous
swellings andintercalated
segments
RB
RBRB
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
16/32
Evidence
for
Nerve
Enlargement
#4
Visser LH, Smidt MH, Lee ML. Diagnostic value of
wrist-forearm ratio in carpal tunnel syndrome
P6
ME
D4
Wrist-forearm ratio:
1.6 in 89 controls
2.4 in 161 patients
with CTS
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
17/32
Evidence
for
Nerve
Enlargement
#4
Visser LH, Smidt MH, Lee ML. Diagnostic value of
wrist-forearm ratio in carpal tunnel syndrome
P6
ME
D4
Therefore:
It is normal for
median nerves to be
enlarged up to 1.6x
at the wrist.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
18/32
Evidence
for
Nerve
Enlargement
#5
Bodor M, McAuliffe M, Derrington S, Uribe Y. – preliminary
unpublished data
P6
D4
Median Palmar Cutaneous Nerve enlargement
between the wrist and palm - Case #1:
Wrist - 0.6 mm2Palm – 1.8 mm2
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
19/32
Evidence
for
Nerve
Enlargement
#5
Bodor M, McAuliffe M, Derrington S, Uribe Y. Preliminary
unpublished data
P6
D4
Median Palmar Cutaneous Nerve enlargement
between the wrist and palm - Case #2:
Wrist - 0.9 mm2 Palm – 2.4 mm2
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
20/32
Evidence
for
Nerve
Enlargement
#5
Bodor M, McAuliffe M, Derrington S, Uribe Y. Preliminary
unpublished data.
P6
D4
Limitations:
- Two cases shown were weight-lifters - predisposing
to MPCN enlargement at the palm.
- Presence of enlargement has been inconsistent
among other subjects.
- MPC has a variable course and may enlarge slightlynext to FCR tendon in wrist.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
21/32
Is there a point at which nerve
enlargement becomes maladaptive?
P6
D4
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
22/32
Median Nerve DML vs CSA at Carpal Tunnel
among Controls (□) and Patients (○)
Adapted from Fujimoto K et al. Diagnosis of severe
carpal tunnel syndrome using electrodiagnosis and
sonography. Ultrasound Med Biol 2015 Oct.
P6
ME
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
23/32
Ulnar Nerve NCV vs. Diameter
among UNE Patients
P6
D4
Adapted from Beekman R et al. Clinical, electrodiagnostic
and sonographic studies at the elbow. Muscle & Nerve
2004.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
24/32
Which graph shows a better correlation
between
Nerve
Size
and
Velocity?
Median (Fujimoto 2015) Ulnar (Beekman 2004)
Note Difference in Population and Parameters!
CSA and DML for Median, Diameter and NCV for Ulnar.
P6
ME
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
25/32
Which graph shows a better correlation
between
Nerve
Size
and
Velocity?
Median (Fujimoto 2015) Ulnar (Beekman 2004)
Note Difference in Population and Parameters!
CSA and DML for Median, Diameter and NCV for Ulnar.
P6
ME 1
/ N C V
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
26/32
Conclusions:
Nerve enlargement can occur in the absence
disease at locations of mechanical stress
susceptible to compression neuropathies.
Nerve enlargement can be a normal adaptive
response which reduces intraneural pressure.
Nerve enlargement within the confines of a bony
space such as the carpal tunnel or spinal canal
becomes maladaptive after a certain point.
Disclaimer: Not all enlargement is adaptive - it
can be secondary to disease.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
27/32
Nerve Adaptation - Flattening
6
N 6
N
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
28/32
Nerve Adaptation - Flattening
222
3 3
3 3
2 2 2
1.5
6
N 6
N
1.5 1.5 1.5
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
29/32
Lateral Femoral CutaneousNerve
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
30/32
Sciatic Nerve
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
31/32
Median compression at proximal retinaculum
with severe flattening of nerve.
-
8/18/2019 Nerve Adaptation in Response to Mechanical Loading_Marko Bodor
32/32
+1 707 322-3162