Inferior Gluteal Nerve Entrapment

Abstract

Inferior gluteal nerve entrapment is a rare (or under-recognized) cause of low back and buttock pain. When the piriformis muscle entraps it, the resulting pain is often misdiagnosed as myofascial pain. The inferior gluteal nerve may also be injured during surgery (especially hip surgery) and poorly placed intramuscular injections. Entrapment of this nerve is commonly seen with (and probably masked by) sciatic, superior gluteal, and posterior femoral cutaneous pathologies.

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Chapter Title Inferior Gluteal Nerve Entrapment
Copyright Year 2016
Copyright Holder Springer International Publishing Switzerland
Corresponding Author Family Name Trescot
Particle
Given Name Andrea M.
Suffix
Division
Organization/University Pain and Headache Center
Street 5431 Mayflower Lane Suite 4
City Wasilla
State AK
Postcode 99654
Country USA
Email DrTrescot@gmail.com
Abstract Inferior gluteal nerve entrapment is a rare (or under-recognized) cause of low
back and buttock pain. When the piriformis muscle entraps it, the resulting
pain is often misdiagnosed as myofascial pain. The inferior gluteal nerve
may also be injured during surgery (especially hip surgery) and poorly placed
intramuscular injections. Entrapment of this nerve is commonly seen with (and
probably masked by) sciatic, superior gluteal, and posterior femoral cutaneous
pathologies.
Keywords (separated
by “ - ”)
Inferior gluteal nerve - Inferior gluteal entrapment - Buttock pain - Gluteal
injuries
AUTHOR QUERIES
Q1 Please provide department name for Andrea M. Trescot.
Q1

© Springer International Publishing Switzerland 2016
A.M. Trescot (ed.), Peripheral Nerve Entrapments: Clinical Diagnosis and Management, DOI 10.1007/978-3-319-27482-9_54
Inferior Gluteal Nerve Entrapment
Andrea M. Trescot
Introduction
Entrapment of the inferior gluteal nerve (IGN) causes but-
tock pain and weakness of the gluteal muscle and usually
occurs in combination with superior gluteal nerve (SGN)
(Chap. 53), posterior femoral cutaneous nerve (PFCN) (see
Chap. 56), and sciatic nerve (Chap. 55) entrapments. It is a
rare (or under-recognized) pathology occurring after buttock
procedures (such as hip surgery) and trauma.
Clinical Presentation (Table 54.1)
The patient with IGN entrapment (IGNE) will present with
pain, weakness, and numbness of the buttocks (Fig. 54.1).
Because of its location, the nerve is often entrapped along
with the PFCN and the sciatic nerve and thus may refer pain
down the posterior thigh (Fig. 54.2).
The IGN is the sole innervation of the gluteus maximus
(GM). The GM acts to extend the trunk at the hip (such as
when extending the trunk from the stooped position) and to
extend the hip when rising from sitting or climbing stairs.
Patients therefore complain of weakness getting out of chairs
or climbing stairs.
Gluteal augmentation (to increase the size and improve
the contour of the buttocks) can traumatize the IGN along its
course within the GM muscle, under which the gluteal
implants are placed. In the same way, posterior and postero-
lateral surgical approaches to the hip may injure the IGN.
Anatomy (Table 54.2)
The IGN arises from the sacral plexus (the L5, S1, and S2
dorsal rami), just one nerve root down from the SGN (see
Chap. 53). The sacral plexus gives rise to the sciatic nerve,
the superior and inferior gluteal nerves, the pudendal nerve
(see Chap. 47), and the posterior femoral cutaneous nerve
(see Chap. 61). The IGN leaves the pelvis with the sciatic
nerve through the sciatic notch below the piriformis (the
[AU1] A.M. Trescot, MD
Pain and Headache Center, 5431 Mayflower Lane Suite 4,
Wasilla, AK 99654, USA
e-mail: DrTrescot@gmail.com
54
Table 54.1 Occupation/exercise/trauma history relevant to inferior
gluteal nerve entrapment
Compression Pelvic pathology
Piriformis entrapment [1]
Direct compression by sciatic lesions
Compression during coma or general
anesthesia [1]
Colorectal cancer [2]
Trauma Intramuscular injections
Surgery Augmentation gluteoplasty [3]
Posterior and posterolateral hip surgeries [4]
Fig. 54.1 Patient localization of inferior gluteal nerve pain (Image
courtesy of Andrea Trescot, MD)
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infra-piriformis foramen) (Fig. 54.3) and bends retrograde
(cephalad) over the piriformis and under the GM. It then
divides into upward and downward branches and supplies
motor innervation to the superior GM muscle (Figs. 54.4,
54.5, and 54.6).
There may also be a branch connecting to the PFCN [5].
Sforsini et al. [6] actually describes the IGN as a branch of
the “posterior cutaneous nerve of the thigh” rather than hav-
ing an independent origin. According to this group, the IGN
(or a branch of the PFCN) has a cutaneous branch that inner-
vates the skin of the lower border of the gluteal region and a
perineal branch that innervates the skin of the perineum and
scrotum/labia majora (which is called the inferior cluneal
nerve by other authors – see Chap. 52).
Skalak and colleagues [7] developed an implantable glu-
teal stimulation device to prevent pressure decubitus ulcers
and needed to find a reliable surface landmark for the “motor
point” of the IGN. Therefore, they dissected nine cadavers
and identified that the IGN could be reliably found at the
junction of a line connecting “the most prominent lateral
borders of the greater trochanters” horizontally with a per-
pendicular vertical line centered at the ischial tuberosity
(Fig. 54.7a).
Because the IGN is vulnerable during posterior
approaches to the hip, Apaydin and colleagues [4] dis-
sected 36 gluteal regions, looking for surgical landmarks
for the IGN. They were able to define a triangular region
that contained the IGN: the apex is the posterior inferior
iliac spine (PIIS); the other two legs connect the greater
trochanter (GT) and the ischial tuberosity (IT) (Fig. 54.7b).
This triangle could be further divided into two regions,
with the superior region being the “danger zone.” In all of
Fig. 54.2 Pain pattern from nerve entrapments of the posterior leg. A
lateral branch iliohypogastric nerve, B superior cluneal nerve, C lateral
femoral cutaneous nerve, D middle cluneal/sacral nerve, E inferior
cluneal nerve, F posterior femoral cutaneous nerve, G obturator nerve,
H femoral nerve, I saphenous nerve, J lateral sural cutaneous nerve, K
superficial peroneal nerve, L medial calcaneal nerve (Image courtesy of
Terri Dallas- Prunskis, MD)
Table 54.2 Inferior gluteal nerve anatomy
Origin Dorsal rami of L5, S1, and S2
General route Lies medial to sciatic nerve and passes out
of the pelvis inferior to the piriformis
through the greater sciatic foramen (the
infra-piriformis foramen). At the lower
border of the piriformis, it divides into
superior-heading and inferior-heading
branches
Sensory distribution None
Motor innervation Sole motor innervation of the gluteus
maximus [5]
Anatomic variability Like the sciatic nerve, the IGN can
congenitally pass through instead of under
the piriformis muscle
Other relevant
structures
Piriformis muscle, sciatic nerve, posterior
femoral cutaneous nerve, and gluteus
minimus
A.M. Trescot
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their specimens, the IGN entered the deep surface of the
GM approximately 5.4 cm from the apex of the GT.
Hwang and colleagues [3] dissected 10 adult Korean
cadavers (20 buttocks) from the infra-piriformis foramen to
the deep surface of the GM in order to measure the relative
depth of the IGN based on the thickness of the GM. Except
for the region below the coccyx-greater trochanter line, the
IGN traveled relatively superficially in the medial portion of
the GM (at a depth less than 70 % of the muscle thickness),
but relatively deeply in the lateral portion of the muscle
(more than 70 % of the thickness).
Like most of the nerve entrapments discussed in this
book, the IGN has several variations in its path, which per-
haps contribute to its entrapment. Tillmann [8] evaluated 112
cadavers; in 17 of them, the IGN left the pelvis through the
piriformis, similar to what is seen occasionally with the sci-
atic nerve (Chap. 55). In three cases, this variation was seen
bilaterally, more often in females than males. In all the cases,
the peroneal division of the sciatic nerve also passed through
the piriformis muscle. The PFCN was seen to often travel
with the IGN through the infra-piriformis foramen.
Entrapment
Pathology of the IGN comes primarily from pelvic pathol-
ogy and intramuscular (IM) injection-related injury of the
SGN and IGN. However, because of the medial intrapelvic
fixation of the IGN at its origin from the sciatic nerve, lum-
bar lordosis and internal rotation of the hip put tension on the
piriformis muscle. This then entraps the IGN between the
piriformis, gluteus minimus, and dorsal rim of the sciatic
notch above and the inferior gluteal blood vessels and lymph
nodes below, creating a vicious cycle, as edema of the
entrapped nerve creates more entrapment. As noted in sec-
tion “Anatomy”, Tillmann [8] evaluated 112 subjects; in 17
Posterior femoral
cutaneous
Pudendal
Superior cluneal
Medial cluneal
Inferior cluneal
Superior gluteal
Inferior gluteal
Sciatic nerve
Fig. 54.3 Anatomy of the
buttock region (Image by
Springer)
Fig. 54.4 Gluteal dissection modified from an image from Bodies, The
Exhibition, with permission (Image courtesy of Andrea Trescot, MD)
54 Inferior Gluteal Nerve Entrapment
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of them, the IGN left the pelvis through the piriformis, simi-
lar to that seen occasionally with the sciatic nerve. Subclinical
EMG changes of the SGN and IGN have been seen in up to
77 % of patients after total hip replacement, regardless of
approach. The IGN can also be injured during intramuscular
augmentation gluteoplasty.
Interestingly, LaBan et al. [2] noted lumbosacral or
buttock pain, cutaneous anesthesia in the PFCN, and EMG
evidence of IGN entrapment in five patients diagnosed
with recurrent colon cancer. They concluded that, due to
the medial intrapelvic origin of the IGN and the “crowd-
ing effect” of the piriformis muscle above, the dorsal rim
[AU5]
Fig. 54.5 MRI axial image of
pelvis. Cg coccygeus muscle, FA
femoral artery, FN femoral nerve,
FV femoral vein, GM gluteus
maximus muscle, Gm gluteus
medius, IG inferior gluteal nerve,
IL iliopsoas muscle, LFC lateral
femoral cutaneous nerve, OI
obturator internis muscle, P
psoas muscle, PE pectineus
muscle, PF posterior femoral
cutaneous nerve, QF quadratus
femoris muscle, RA rectus
abdominis muscle, RF rectus
femoris muscle, RL round
ligament, SA sartorius muscle,
SN sciatic nerve, TFN tensor
fascia lata muscle (Image
courtesy of Andrea Trescot, MD)
[AU2]
[AU3]
Fig. 54.6 MRI coronal images
showing gluteal muscles and
nerves. AC Alcock’s canal, CL
superior cluneal nerve, IL iliac
crest, IG inferior gluteal nerve, Ig
inferior gemellus muscle, IT
ischial tuberosity, Pi piriformis,
Pu pudendal, Gmi gluteus
minimus, Gme gluteus medius,
Gma gluteus maximus, GT
greater trochanter, LA levator ani
muscle, OI obturator internus
muscle, PF posterior femoral
cutaneous nerve, PU pudendal
nerve, PUr pudendal nerve
(rectal branch), QF quadratus
femoris muscle, SA sacrum, SGN
superior gluteal nerve, Sg
superior gemellus muscle, SI
sacroiliac joint, SN sciatic nerve
(Image courtesy of Andrea
Trescot, MD)
[AU4]
A.M. Trescot
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of the sciatic notch behind, and the inferior gluteal vessels
and nodes below, the IGN was particularly susceptible to
entrapment by colorectal cancer. IGN entrapment should
be considered in patients with hypoesthesia over the infe-
rior lateral buttocks and a history of colorectal
malignancy.
Physical Exam
Patients with IGNE may have a GM “lurch” – when the
GM is weak, the trunk hyperextends with heel strike to
compensate for weak hip extension (see https://www.you-
tube.com/watch?v=bTQ5ID7Tpa4 for a video demonstra-
tion, courtesy of Dr. Nabil Ebraheim, with permission).
Palpation of the IGN is similar to that of the sciatic nerve or
PFCN. With the patient standing and flexed at the hips,
identify the piriformis muscle; the IGN is at the inferior
border of the piriformis, superior to the ischial tuberosity
(Fig. 54.8).
Differential Diagnosis (Table 54.3)
It can be difficult to differentiate IGN dysfunction from a
variety of gluteal pathologies, including sciatic nerve entrap-
ment (Chap. 55), piriformis syndrome, PFCN entrapment
(Chap. 56), and pathology of the sacroiliac or L5 facet joints
or superior cluneal (Chap. 51) or inferior cluneal nerves
(Chap. 52). It is not uncommon to have several concurrent
entrapments from piriformis spasm (IGN, sciatic, and
PFCN), since they travel together. Since the treatment is sim-
ilar, there may be no clinical need to differentiate, at least
early on. The history and mechanism of injury may provide
the most useful information. Table 54.4 lists the diagnostic
tests for IGNE.
ab
Fig. 54.7 (a) Location of the
IGN using the landmarks
described by Skalal et al. [7].
(b) “Danger” triangle by
Apaydin et al. [4] identifying the
location of the inferior gluteal
nerve (Image courtesy of Andrea
Trescot, MD)
Fig. 54.8 Physical exam of the inferior gluteal nerve (Image courtesy
of Andrea Trescot, MD)
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Identification and Treatment of Contributing
Factors
Piriformis muscle spasm is the major factor contributing to
entrapment and perhaps a “double crush” situation (see
Chap. 1). Piriformis stretches and injections can be very
useful, and botulinum toxin may be appropriate for recalci-
trant cases. De Jong and van Weerden [10] described a
patient with substantial lordosis from wearing high heels
that led to piriformis entrapment of the SGN and IGN. The
resulting lack of gluteal muscle function resulted in a hip
fracture.
Knowing the location of the IGN should decrease the risk
of iatrogenic injury during IM injections and hip surgery.
Apaydin et al. [4] stated that the posterior approach to the
hip, while the most common, was more likely to result in
damage to the IGN. Ling and Kumar [11] recommended a
muscle-splitting incision not more than 5 cm medial to the
greater trochanter to avoid the IGN. Hwang et al. [3] (see
section “Anatomy”) concluded that intramuscular augmenta-
tion gluteoplasty could be performed without injuring the
IGN, as long as the dissection was not extended too deeply.
Injection Technique
Since IGNE is not well recognized, there is relatively little
literature on the injection techniques for this nerve. Most of
the techniques described here are modifications of tech-
niques used to treat other nerves in the area.
Landmark-Guided Technique
For the landmark-guided injection, the patient is positioned
standing, flexed at the hips, which tightens the gluteal tissues
and makes palpation of the structures easier. Alternatively,
especially if a peripheral nerve stimulator is to be used, the
patient can be placed prone. The inferior border of the piri-
formis muscle is palpated, and the maximal tenderness iden-
tified, medial to the midbody of the muscle (Fig. 54.9). A
25-gauge 2-in. needle is usually all that is necessary, though
Table 54.3 Differential diagnosis of buttock pain
Potential distinguishing features
Lumbar spine disorders Physical exam and MRI scan should
confirm the diagnosis
Sacroiliac joint
disorders
Pain may be present in the lower back,
back of hips, groin, and thighs. Physical
exam, X-rays, CT, and MRI scans can
help identify pathology. Relief of pain
from a SI joint injection will confirm the
diagnosis
Piriformis or gluteus
medius spasm
Tenderness and spasm of the muscles,
stretching the muscle will increase the
pain; trigger point injections into the
muscle will alleviate the symptoms
Posterior rami
syndrome,
thoracolumbar junction
syndrome (Maigne
syndrome), and dorsal
ramus syndrome
Pain is relieved by injection of local
anesthetic into the T12/L1 facet joint
Sciatic entrapment US shows compression of the nerve (see
Chap. 55)
DJD hip X-rays show degenerative changes
Posterior femoral
cutaneous nerve
Pain radiates down the leg
Table 54.4 Diagnostic tests for inferior gluteal nerve entrapment
Potential distinguishing features
Physical exam Tenderness inferior to the piriformis, medial
to sciatic nerve
Diagnostic injection Landmark or US injection inferior to
piriformis muscle
Ultrasound Not described, but the location of the sciatic
nerve will identify the direction to the IGN
MRI The IGN can be seen on coronal images,
exiting the pelvis adjacent to the sciatic
nerve. With IGN injury, there may be signal
abnormalities in the gluteus maximus [5]
Arteriography Not useful
X-ray Not useful
Electrodiagnostic
studies
May show denervation pattern of the gluteus
maximus [2]; EMG abnormalities in 77 %
of patients after total hip replacements [9]
Fig. 54.9 Landmark-guided injection of the inferior gluteal nerve
(Image courtesy of Andrea Trescot, MD)
A.M. Trescot
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for the morbidly obese, a 22-gauge 3-in. Quincke needle
may be needed. As described above, a peripheral nerve stim-
ulator may be useful, seeking stimulation of the GM and not
the posterior leg (which would be the sciatic nerve).
Fluoroscopy-Guided Technique
There are no specific fluoroscopic landmarks for the IGN,
but, since it travels with the PFCN, a similar technique could
be used (see Chap. 56) (Fig. 54.10).
Ultrasound-Guided Technique
There are no published descriptions of US-guided IGN injec-
tions. However, when using an US-guided approach to the
sciatic nerve at the level of the piriformis, the IGN should be
medial to the sciatic nerve.
Neurolytic/Surgical Technique
There are no published cryoneuroablation or radiofrequency
techniques described.
Complications
Because of the proximity of the sciatic nerve, there is a risk
of sciatic nerve anesthesia (from spillover of the local anes-
thetic) or sciatic nerve damage from the needle.
Summary
IGN entrapment is not well recognized, which probably con-
tributes to the limited available literature. This nerve is in the
same area as the sciatic and posterior femoral cutaneous
nerves, both of which can cause severe pain in the buttocks.
Inferior gluteal entrapment should be considered in the
patient with buttock pain.
References
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inferior and superior gluteal nerves due to hypertrophy of pirifor-
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2. LaBan MM, Meerschaert JR, Taylor RS. Electromyographic evi-
dence of inferior gluteal nerve compromise: an early representation
of recurrent colorectal carcinoma. Arch Phys Med Rehabil.
1982;63(1):33–5.
3. Hwang K, Nam YS, Han SH, Hwang SW. The intramuscular course
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augmentation gluteoplasty. Ann Plast Surg. 2009;63(4):361–5.
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course of the inferior gluteal nerve and surgical landmarks for its
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Fig. 54.10 Fluoroscopic landmarks of the inferior gluteal nerve
(Image courtesy of Andrea Trescot, MD)
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Author Queries
Chapter No.: 54 0002678395
Queries Details Required Author’s Response
AU1 Please provide department name for Andrea M. Trescot.
AU2 Both “Gm” and “Gme” for gluteus medius have been used in text. Please check if one form should be made
consistent.
AU3 Please check if “PF” should be changed to “PFCN” for consistency.
AU4 Please check if “PF” should be changed to “PFCN” for consistency.
AU5 Please expand EMG.