Download needle emg examination of the foot

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David A. Park,
Tracy
AMERICAN ASSOCIATION OF NEUROMUSCULAR &
ELECTRODIAGNOSTIC MEDICINE
2621 Superior Drive NW
Rochester, MN 55901
(507) 288-0100
[email protected]
www.aanem.org
AMERICAN ASSOCIATION OF NEUROMUSCULAR &
ELECTRODIAGNOSTIC MEDICINE
Workshop handouts are prepared as background didactic material to complement a hands-on workshop session.
This workshop handout was originally prepared in September 2000 and revised in September 2008. The idea and
opinions in this publication are solely those of the author(s) and do not necessarily represent those of the AANEM.
Copyright © September 2000
AMERICAN ASSOCIATION OF NEUROMUSCULAR &
ELECTRODIAGNOSTIC MEDICINE
2621 Superior Drive NW
Rochester, MN 55901
Needle EMG Examination of the Foot
David R. Del Toro, MD
Department of Physical Medicine and Rehabilitation
Medical College of Wisconsin
Milwaukee, Wisconsin
Tracy A. Park, MD
Medical Rehabilitation Associates
Milwaukee, Wisconsin
INTRODUCTION
The intrinsic muscles of the foot are affected by a wide variety
of neurogenic disorders, including peripheral polyneuropathy,
lumbosacral radiculopathy/plexopathy, and entrapment/compression mononeuropathies of the sciatic, deep peroneal, and
tibial nerves. Although this discussion addresses the technical
aspects of needle electromyography (EMG) examination of
the foot, the approach to this technique will be presented in
terms of entrapment neuropathies within the foot.
Needle EMG examination of the intrinsic muscles of the foot
is perhaps the most under-utilized of all the tools available to
electrodiagnostic medicine (EDX) consultants. There are
several reasons for this. One is that several published articles
have reported the common occurrence of prolonged
insertional activity in the intrinsic foot muscles of normal
subjects.7,8,27 These findings were refuted by Dumitru et al in a
later study, which found true abnormal spontaneous activity in
2% of 50 healthy, asymptomatic subjects.7 A second reason is
that many EDX consultants believe that needle examination of
the foot muscles isprohibitively painful to the patient. However,
most EDX consultants routinely insert needle electrodes into a
variety of hand muscles, even though this procedure often
elicits more pain in the hand muscles than it does in the foot
muscles. And finally, many EDX consultants are uncomfortable with the technique and interpretation of needle EMG examination of the foot muscles. This is because, in the majority
of institutions, there is so little time and attention dedicated to
this topic by residency/fellowship training programs and continuing medical education programs. This workshop addresses
the last of these reasons, with the hope that the participants will
develop an understanding of the anatomic principles,
electrophysiologic approach and technique, and clinical
interpretation of needle EMG examination of the foot.
ANATOMY
With the exception of the extensor digitorum brevis (EDB),
which is innervated by the deep peroneal nerve (L5/S1), the
intrinsic muscles of the foot receive their nerve supply from
three branches of the tibial nerve: the medial plantar nerve
(MPN), the lateral plantar nerve (LPN), and Baxter’s nerve
(more formally referred to as the inferior calcaneal nerve or the
1st branch of the LPN). All of these tibial nerve branches carry
fibers from the S1 and S2 nerve roots.
Tibial Nerve
At the level of the medial malleolus, the tibial nerve lies within
the tarsal tunnel, deep to the flexor retinaculum (Figure 1), and
is encased within a tunnel along with the remainder of the tibial
neurovascular bundle. There is a distinct compartment for the
tibial nerve within the upper tarsal tunnel which is a site of
potential compression of the tibial nerve itself or one or more
of the tibial nerve branches. This compartment is formed by the
calcaneal attachment of the deep aponeurotic segment of the
flexor retinaculum.24
2
Needle EMG Examination of the Foot
In 93 - 95% of feet, the MPN and LPN branch off the tibial
nerve within the tarsal tunnel.6,12 (For the purposes of EDX
testing, it is helpful to think of the tibial nerve as actually
having 4 terminal branches: the MPN, the LPN, Baxter’s
nerve, and the medial calcaneal nerve.19) The first three of
these carry motor fibers and are described below. The fourth
branch (the medial calcaneal nerve) is purely sensory and will
not be discussed here.
In the lower tarsal tunnel, still at the level of the calcaneus,
the tunnel for the tibial nerve divides into upper and lower
calcaneal chambers that are separated by the interfascicular
septum. (Figure 1) The interfascicular septum is actually
a segment of the deep fascia of the abductor hallucis
extending towards its attachment to the medial aspect of
the calcaneus. The upper calcaneal chamber contains the
MPN, while the lower calcaneal chamber houses the LPN.
These calcaneal chambers represent a second site of
entrapment of the individual plantar nerves. Although
Baxter’s nerve initially enters the lower chamber, it follows
a different course from that of the plantar nerves, veering
to penetrate the posterior aspect of this chamber and
traveling laterally across the foot anterior to the calcaneus.24
Therefore, unlike the plantar nerves, Baxter’s nerve does
not tend to be entrapped in the calcaneal chambers.
Medial Plantar Nerve (MPN)
After exiting the upper calcaneal chamber, the MPN travels into
the sole of the foot via the abductor canal,24 which is formed by
the attachment of the abductor hallucis to the talus and navicular.16,17,21 The abductor canal is another known entrapment site
of the MPN.16,17,21 The MPN innervates the abductor hallucis,
flexor hallucis brevis (medial and lateral heads), flexor digitorum
brevis, and 1st lumbrical.
Lateral Plantar Nerve (LPN)
The LPN leaves the lower calcaneal chamber and passes
into the sole of the foot through its own abductor canal,
which (like that of the MPN) is formed by the attachment
of the abductor hallucis to the talus and navicular. The
abductor canal of the LPN is a potential entrapment site
for this nerve as well. The LPN then passes in an oblique
fashion laterally and distally across the foot, sandwiched
between the flexor digitorum brevis (on the plantar side)
and the quadratus plantae (on the dorsal side).24 After piercing the lateral intermuscular septum, the LPN divides into
its terminal superficial and deep branches, opposite the
base of the 5th metatarsal.24 The LPN provides motor
innervation to the quadratus plantae, flexor digiti minimi
brevis, flexor hallucis brevis (lateral head), adductor
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hallucis, all interossei, and the second through fourth
lumbricals.24 It should be noted that the medial branch of
the deep peroneal nerve may frequently send motor twigs
to the dorsal interossei.1
MCN
Baxter’s nerve
Figure 1: Schematic drawing of the medial aspect of a right
foot, illustrating the tarsal tunnel and the tibial nerve with its four
terminal branches. (TN, tibial nerve; MCN, medial calcaneal
nerve; Baxter’s nerve; QP, quadratus plantae muscle; LPN,
lateral plantar nerve; MPN, medial plantar nerve; IFS, interfascicular septum; AH, abductor hallucis muscle; FR, flexor retinaculum).
Baxter’s Nerve (Inferior Calcaneal Nerve; 1st
branch of LPN)
Baxter’s nerve, originally named the inferior calcaneal
nerve when it was first described by Roegholt in 1940,22
has also been referred to as “the first branch of the lateral
plantar nerve,”23 “the muscle branch of the lateral plantar
nerve,”19 or “the nerve to the abductor digiti quinti.”11
In the upper tarsal tunnel, Baxter’s nerve arises either from
the tibial nerve prior to the MPN/LPN bifurcation,
or from the LPN itself just after its origin.24 After passing
through the posterior segment of the lower calcaneal
chamber, Baxter’s nerve heads inferiorly between the deep
fascia of the abductor hallucis and the underlying quadratus
plantae.24 As it passes the quadratus plantae, Baxter’s nerve
takes a sharp turn toward the lateral side of the foot.
It follows a horizontal and transverse course immediately
anterior to the medial aspect of the calcaneal tuberosity
while passing between the overlying flexor digitorum brevis
and the underlying quadratus plantae.24 (Figure 2) Baxter’s
nerve can be compressed between the quadratus plantae
and abductor hallucis,2,4,20,23 or by a heel spur at the medial
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Needle EMG Examination of the Foot
calcaneal tuberosity.4,16,20,26 (In the authors’ experience,
Baxter’s nerve is the most commonly entrapped nerve
in the foot.) Baxter’s nerve always terminates with motor
branches to the abductor digiti quinti pedis, and may send
motor branches to the quadratus plantae and flexor
digitorum brevis.2,5,18,20,23
3
interossei (10.5% in the second; 2.6% in the third).1
Either or both DPN branches can become entrapped
beneaththe inferior extensor retinaculum, causing the socalled ‘anterior tarsal tunnel syndrome.’
Baxter's
Nerve
Figure 3: Schematic drawing of the terminal course of the deep
Figure 2: Schematic drawing of the posterior view of the heel
showing how Baxter’s nerve can be entrapped between the abductor hallucis and the medial edge of the quadratus plantae. At this site,
Baxter’s nerve is particularly vulnerable to excessive traction during
pronation. (Used with permission from Schon LC, Baxter DE. Heel
pain syndrome and entrapment neuropathies about the foot and
ankle. In: Gould JS, editor. Operative foot surgery. Philadelphia: WB
Saunders; 1994. p 193.)
peroneal nerve (DPN). Note that the DPN typically divides
above the inferior extensor retinaculum into a medial branch,
which innervates the first dorsal web space, and a lateral branch,
which innervates the extensor digitorum brevis. (Adapted with
permission from Liveson JA. In: Peripheral neurology: case
studies in electrodiagnosis, 2nd edition. Philadelphia: FA Davis;
1991. p 53.)
Deep Peroneal Nerve
NEEDLE EMG EXAMINATION OF SELECTED
FOOT MUSCLES
After branching from the common peroneal nerve
just distal to the fibular neck, the deep peroneal nerve
(DPN) courses between the muscle layers of the anterior
compartment on its way to the foot. The DPN then
divides into medial and lateral branches 1.3 cm proximal
to the ankle joint.12 Both of these branches then pass
deep to the inferior extensor retinaculum. (Figure 3) The
medial branch supplies cutaneous innervation to the first
dorsal web space, while the lateral branch provides the
motor innervation to the extensor digitorum brevis.
(Figure 3) In addition, the edial branch of the DPN may
frequently provide some innervation to the dorsal interossei.1 A recent anatomic study reported a 92.1% incidence of DPN motor branches to the first dorsal
interosseus pedis, with the incidence falling off sharply in
a medial-to-lateral manner in the remaining dorsal
Needle EMG examination of various intrinsic foot
muscles is a useful tool in the EDX consultant’s
armamentarium and can yield extremely valuable
information to assist in developing the EDX
impression. Unfortunately, most EDX consultants are
comfortable with needle EMG examination of only
a couple of the intrinsic foot muscles (i.e.,
extensor digitorum brevis and first dorsal interosseus
pedis). Even widely used reference books for
needle EMG techniques include only a very limited
number of intrinsic foot muscles.10 The following section
will describe in detail how to perform needle
EMG examination of numerous intrinsic foot
muscles along with their most likely peripheral
innervation pattern.
4
Needle EMG Examination of the Foot
Due to individual variation in dexterity and coordination of
the different intrinsic foot muscles, an EDX consultant
may not always be able to evaluate the selective voluntary
recruitment of early individual motor units (i.e., first-,
second-, or third-order motor units). However, one should
be able to elicit multiple voluntary motor units and possibly
evaluate the interference pattern of these motor units by
simple telling the patient, “Try to wiggle your toes.”
First Dorsal Interosseus Pedis (FDIP)
The first dorsal interosseus pedis (FDIP) is innervated by the
LPN (although it often receives a branch from the DPN as
well).1 For needle EMG examination of the FDIP, the needle
electrode is inserted into the first dorsal web space immediately proximal to the first and second metatarsal heads, with
the tip angled slightly toward the heel. (Figure 4) This angle
will direct the EMG needle into the mid-shaft level of the
metatarsals, where the space between these bones is the widest.
The first muscle encountered by the needle electrode in this
space will be the FDIP. To confirm needle electrode placement
into the FDIP, the patient can recruit this muscle by attempting resisted abduction and/or flexion of the first and second
toes. Needle EMG examination of the FDIP should then
proceed with investigation of the muscle’s insertional activity,
spontaneous activity, motor unit recruitment, and motor unit
action potential morphology.
Figure 4: Needle electrode placement for EMG examination of
first dorsal interosseus pedis (FDIP). The needle electrode is
inserted into the first dorsal web space immediately proximal to
the first and second metatarsal heads, and is angled toward the
heel. This angle will direct the EMG needle into the mid-shaft
level of the metatarsals, where the space between these bones
is the widest.
Fourth Dorsal Interosseus Pedis (Fourth DIP)
The fourth dorsal interosseus pedis (fourth DIP) is
innervated by the LPN, exclusively. Needle electrode insertion is
similar to the FDIP technique, with the electrode inserted into
the fourth dorsal web space immediately proximal to the fourth
and fifth metatarsal heads. (Figure 5) Again, the needle electrode
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is angled toward the heel to direct it into the space between the
metatarsal shafts. The first muscle encountered by the needle
electrode in this space will be the fourth DIP. Needle electrode
placement is confirmed by having the patient recruit the fourth
DIP with resisted abduction and/or flexion of the fourth and
fifth toes. Alternatively, the EDX consultant can place a finger
between the fourth and fifth toes and then have the patient
attempt resisted adduction of these toes. Needle EMG examination of the fourth DIP can then proceed in the usual fashion
as described for the FDIP.
Figure 5: Needle electrode placement for EMG examination of
fourth dorsal interosseus pedis (fourth DIP). The needle electrode is inserted into the 4th dorsal web space immediately
proximal to the fourth and fifth metatarsal heads. The needle
electrode is angled toward the heel to direct it into the space
between the metatarsal shafts.
Flexor Digiti Minimi Brevis (FDMB)
The flexor digiti minimi brevis (FDMB) is the short flexor of
the little toe. Like the fourth DIP, it is exclusively innervated by the LPN. The needle electrode is inserted at the lateral
aspect of the forefoot at the midpoint of the 5th metatarsal shaft.
(Figure 6) The needle tip should pierce the thinner dorsal skin
(immediately superior to the border of the plantar skin). The
needle electrode is directed across the foot, just inferior to the
5th metatarsal shaft. Needle electrode placement is confirmed
by having the patient flex the toes. Needle EMG examination of
the FDMB can then proceed in the usual fashion as described
for the FDIP.
Abductor Digiti Quinti Pedis (ADQP)
The abductor digiti quinti pedis (ADQP) is always
innervated by Baxter’s nerve.19 For needle EMG examination
of the ADQP, the needle electrode tip is inserted at (or up to
about 0.5 cm superior to) the junction of the dorsal and
plantar skin (so the tip pierces the thinner dorsal skin, and not
the thick plantar skin) and approximately 1 to 2 fingerbreadths
proximal to the base of the 5th metatarsal. (Figure 7) The
electrode shaft should be directed posteriorly at about a
45-degree angle, an orientation that will guide it into the bulk
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Needle EMG Examination of the Foot
of the ADQP muscle belly. The needle electrode is then
advanced until insertional activity of the muscle is detected.
Needle electrode placement in the ADQP is confirmed by
having the patient abduct and/or flex the fifth toe against
resistance. If the patient is unable to do this, the examiner can
place a finger against the lateral side of the fifth toe and have
the patient externally rotate the foot against this resistance; the
ADQP should contract automatically in order to stabilize the
fifth toe. Needle EMG examination of the ADQP then
proceeds in the usual manner.
5
Abductor Hallucis (AH)
The abductor hallucis (AH) is innervated by the MPN.
Needle EMG examination of the AH begins with palpation
of the muscle belly just posterior and inferior to the navicular tuberosity. The needle electrode is inserted about 2 cm
posterior to the navicular tuberosity, at (or immediately
superior to) the junction of the dorsal and plantar skin.
(Figure 8) The electrode shaft can be directed posteriorly
(at about a 45-degree angle) or slightly distally. When
advancing the needle electrode, one must be cognizant of
the medial and lateral plantar nerves which are nearby but
deep to the AH. After observing insertional activity of the
muscle, the EDX consultant can confirm needle electrode
placement by having the patient attempt abduction and/or
flexion of the first toe. Alternatively, the examiner can
place a finger against the lateral side of the first toe
and have the patient internally rotate the foot against this
resistance; the AH should contract automatically in order to
stabilize the first toe. Needle EMG examination of the AH
an then proceed in the usual fashion.
Figure 6: Needle electrode placement for EMG examination of
flexor digiti minimi brevis (FDMB). The needle electrode is inserted
at the lateral aspect of the forefoot at the midpoint of the 5th metatarsal shaft. The needle tip should pierce the thinner dorsal skin (immediately superior to the border of the plantar skin).The needle
electrode is directed across the foot, just inferior to the 5th metatarsal shaft.
Figure 7: Needle electrode placement for EMG examination of
Figure 8A and 8B: Needle electrode placement for EMG
abductor digiti quinti pedis (ADQP). The needle electrode tip is
inserted at (or immediately superior to) the junction of the
dorsal and plantar skin (so the tip pierces the thinner dorsal skin)
and approximately 1 to 2 fingerbreadths proximal to the base of
the 5th metatarsal (see mark in figure). The electrode shaft
should be directed posteriorly at about a 45-degree angle, an
orientation that will guide it into the bulk of the ADQP
muscle belly.
examination of abductor hallucis (AH). The needle electrode is
inserted about 2 cm posterior to the navicular tuberosity, at (or
immediately superior to) the junction of the dorsal and plantar
skin (the needle tip piercing the thinner dorsal skin). The electrode shaft can be directed posteriorly at about a 45-degree
angle (A), or slightly distally (B). When advancing the needle
electrode, one must be cognizant of the medial and lateral
plantar nerves which are nearby but deep to the AH.
6
Needle EMG Examination of the Foot
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Figure 9A and 9B: Needle electrode placement for EMG
examination of extensor digitorum brevis (EDB). The needle
electrode tip is inserted into the lateral edge of the EDB at the
midpoint of the muscle belly (A). If there is little or no palpable
EDB muscle mass, the needle electrode is inserted about 2 cm
posterior and 2 cm superior to the base of the fifth metatarsal. The
bellies of the EDB lie lateral to and deep to the tendons of the
extensor digitorum longus. An attempt should be made to explore
all four muscle bellies by directing the needle electrode in a very
shallow angle medially across the foot (B), thereby allowing the
needle to pass just deep to the long extensor tendons.
Extensor Digitorum Brevis (EDB)
The extensor digitorum brevis (EDB) is innervated by the
DPN. Prior to needle electrode insertion, the EDB muscle
mass is palpated to determine its lateral edge. The needle
electrode tip is inserted into the lateral edge of the EDB at
about the midpoint of the muscle belly. (Figure 9) If there
is little or no palpable EDB muscle mass, the needle electrode is inserted about 2 cm posterior and 2 cm superior to
the base of the fifth metatarsal. The bellies of the EDB lie
lateral to and deep to the tendons of the extensor digitorum longus. An attempt should be made to explore all four
bellies by directing the needle electrode in a very shallow
angle medially across the foot, thereby allowing the needle
to pass to the long extensor tendons, where the two most
medial bellies are located. Needle electrode placement into
the EDB is easily confirmed by having the patient gently
and slowly extend the toes. Needle EMG examination of
the EDB can then proceed in the usual manner.
DISCUSSION
The needle EMG examination of intrinsic foot muscles is critical in the EDX evaluation of the foot. 14,25 Unfortunately,
several published and widely recognized studies have reported
abnormally prolonged insertional activity in the intrinsic muscles
in a significant percentage of normal feet.7,8,27 However, none of
these studies have been able to demonstrate spontaneous
activity, in the form of sustained positive sharp waves or
fibrillation potentials, in the intrinsic foot muscles of
any normal subjects. In fact, a more recent study by Dumitru
et al7 examining the AH and EDB in 50 healthy asymptomatic subjects demonstrated “truly abnormal” spontaneous single muscle fiber discharges (i.e., fibrillation
potentials and positive sharp waves) in only 2% (1/50 feet). To
explain the findings in the previous studies,7,8,27 Dumitru et
al concluded: “It is likely that the previously reported high
prevalence of spontaneous activity in healthy persons resulted
from not fully appreciating the similarity between innervated
and denervated spontaneous single muscle fiber discharge
configurations.” 7 In addition, none of these earlier studies have
included nerve conduction studies (NCS) on the nerves of
the ‘normal’ feet to assess for subclinical or asymptomatic nerve
dysfunction.7,8,27 However, despite the flaws in these reports,
many EDX consultants avoid performing needle EMG
examination on intrinsic foot muscles, since they are uncertain
of how to interpret any observed abnormalities or how such
abnormalities might be diagnostically useful.
The authors have consistently found needle EMG abnormalities (i.e., sustained positive sharp waves and fibrillation
potentials) to be the most frequent ‘positive’ finding in the
electrophysiologic evaluation of patients with suspected
entrapment neuropathies in the foot−‘positive’ not in a
random manner, but in a logical way that ‘fits’ the clinical
presentation. This experience supports the theory that
axonal degeneration is the pathologic mechanism for tarsal
tunnel syndrome.14 Furthermore, the authors have found
needle EMG examination to be both more specific and
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Needle EMG Examination of the Foot
more sensitive than NCSs for diagnosing entrapment
neuropathies in the foot. Because the needle EMG
abnormalities that have been reported in asymptomatic feet
have been quite mild, more prominent findings (i.e., 1+ or
greater abnormal spontaneous activity in the form of
sustained positive sharp waves and/or fibrillation potentials) must be demonstrated to indicate denervation beyond
what would be considered normal ‘wear and tear.’
Additionally, the clinical significance of any abnormal
EMG findings in a given intrinsic foot muscle should be
corroborated by studying the same muscle in the unaffected
foot: asymmetric findings would suggest a focal pathology
rather than normal ‘wear and tear’.
Just as important as the performance of the needle EMG
examination of the intrinsic foot muscles is the decision of
which muscles to explore in a given patient. It must be realized
that examining a single muscle (e.g., the abductor hallucis) to
‘screen’ for the presence of tarsal tunnel syndrome is grossly
inadequate, since more distal entrapment of individual tibial
nerve branches is a frequent cause of symptoms resembling
tarsal tunnel syndrome. Also, neurogenic symptoms in the foot
are often vague and poorly localized, so these factors are not
always reliable in guiding the examiner to the involved nerve.
Adding to this limitation is the fact that entrapment neuropathies in the foot rarely result in complaints of weakness;
instead, the symptoms are typically numbness, pain, and/or
paresthesias. Therefore, weakness is virtually eliminated as a
basis for choosing which intrinsic foot muscles
to explore.
Because intrinsic foot muscles often have needle EMG
abnormalities in clinical conditions other than a nerve
entrapment in the foot, such as a peripheral polyneuropathy
and lumbosacral radiculopathy, it is important to expand
the scope of the needle EMG examination to investigate
these other possibilities. Abnormalities in a given nerve
distribution or muscle should lead to evaluation of intrinsic
muscles supplied by a different nerve, and possibly the intrinsic muscles of the opposite foot. Limb muscles proximal to the foot, as well as the lumbosacral paraspinal
muscles, may also need to be explored, depending on the
overall clinical picture.
Ultimately, like any other electrophysiologic information,
the results of the needle EMG examination of the intrinsic
foot muscles must be considered in conjunction with the
patient’s clinical presentation. The history, physical examination, NCSs, and needle EMG examination must all come
together to create a logical ‘fit,’ one that makes anatomic
and physiologic sense.
7
REFERENCES
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2. Arenson DJ, Cosentino GL, Suran SM. The inferior calcaneal nerve: An
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3. Baxter DE, Pfeffer GB, Thigpen M. Chronic heel pain:Treatment rationale. Orthop Clin North Amer 1989;20:563-569.
4. Baxter DE, Pfeffer GB. Treatment of chronic heel pain by surgical release
of the first branch of the lateral plantar nerve. Clin Orthop Rel Res
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5. Baxter DE, Thigpen M: Heel pain. Operative results. Foot Ankle 1984;5:1625.
6. Dellon AL, Mackinnon SE. Tibial nerve branching in tarsal tunnel. Arch
Neurol 1984;41:645-646.
7. Dumitru D, Diaz CA, King JC. Prevalence of denervation in paraspinal and
foot intrinsic musculature. Am J Phys Med Rehabil 2001;80:482-490.
8. Falck B, Alaranta H. Fibrillation potentials, positive sharp waves and fasciculation in the intrinsic muscles of the foot in healthy subjects. J Neurol
Neurosurg Psychiatr 1983;46:681-683.
9. Gatens PF, Saeed MA. Electromyographic findings in the intrinsic muscles of
normal feet. Arch Phys Med Rehabil 1982;63:317-318.
10. Geiringer SR. Anatomic Localization for Needle Electromyography. Hanley
& Belfus, Philadelphia, 1993.
11. Hamm JT, Sanders M. Anatomic variations of the nerve to the abductor
digiti quinti muscle. Foot Ankle 1987;8:123.
12. Havel PE, Ebraheim NA, Clark SE, Jackson WT, DiDio L. Tibial nerve
branching in the tarsal tunnel. Foot Ankle 1988;9:117-119.
13. Horwitz MT. Normal anatomy and variations of the peripheral nerves of
the leg and foot. Arch Surg 1938;36:626-636.
14. Kraft GH. Tarsal tunnel entrapment. In: Course E: Entrapment neuropathies. AAEE Ninth Annual Continuing Education Course, Boston.
September 25, 1986, pp 13-18.
15. Mackinnon SE, Dellon AL, Daneshvar A. Tarsal tunnel syndrome:
Histopathologic examination of a human posterior tibial nerve. Contemp
Orthop 1984;9:43-48.
16. Murphy PC, Baxter DE. Nerve entrapment of the foot and ankle in runners.
Clin Sports Med 1985;4:753-76368.
17. Oh SJ, Lee KW. Medial plantar neuropathy. Neurology 1987;37:1408-1410
18. Park TA, Del Toro DR. Case report: isolated inferior calcaneal neuropathy.
Muscle Nerve 1996;19:106-8.
19. Park TA, Del Toro DR. Electrodiagnostic evaluation of the foot. Phys Med
Rehabil Clin N Amer 1998;9:871-896.
20. Przylucki H, Jones CL. Entrapment neuropathy of muscle branch of lateral
plantar nerve. J Amer Podiatry Assoc 1981;71:119-124.
21. Rask MR. Medial plantar neurapraxia (“jogger’s foot”): Report of 3 cases.
Clin Orthop Rel Res 1978;134:193-195.
22. Roegholt MN. Een nervus calcaneus inferior als overbrenger van de pijn bij
calcaneodynie of calcanensspoor en de daaruit volgende therapie. Ned
Tijdschr v Geneeskd 1940;84:1898.
23. Rondius JJ, Huson A. The first branch of the lateral plantar nerve and heel
pain. Acta Morphol Neerl Scand 1986;24:269.
24. Sarrafian SK. Anatomy of the Foot and Ankle. Philadelphia, JB Lippincott
Company, 1983.
25. Spindler HA, Reischer MA, Felsenthal G. Electrodiagnostic assessment in
suspected tarsal tunnel syndrome. Phys Med Rehabil Clin N Amer
1994;5:595-612.
26. Tanz SS. Heel pain. Clin Orthop 1963;28:169-177.
27. Wiechers D, Guyton JD, Johnson EW. Electromyographic findings in the
extensor digitorum brevis in a normal population. Arch Phys Med Rehabil
1976;57:84-85.
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Del T MD
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David A. Park,
Tracy
AMERICAN ASSOCIATION OF NEUROMUSCULAR &
ELECTRODIAGNOSTIC MEDICINE
2621 Superior Drive NW
Rochester, MN 55901
(507) 288-0100
[email protected]
www.aanem.org
AMERICAN ASSOCIATION OF NEUROMUSCULAR &
ELECTRODIAGNOSTIC MEDICINE