Extra spinal causes of sciatica and a causes algorithm

Bahaa Ali Kornah
Prof. of Orthopedic Surgery
Al-Azhar university , Cairo, Egypt
Bahaa Kornah -AlAzhar UN. Cairo Egypt
Abstract Number: 52575

 EXTRASPINAL SCIATICA
=
 Non-discogenic sciatica (NDS)

SCIATICA
 Sciatica
 Is a set of symptoms including pain that may be caused
by general compression and/or irritation of one of five
spinal nerve roots that give rise to each sciatic nerve, or
by compression or irritation of the left or right or both
sciatic nerves.

❖The pain is felt in the lower back, buttock,
and/or various parts of the leg and foot.
❖Numbness,
❖Muscular weakness,
❖Pins and needles or tingling and
❖Difficulty in moving or controlling the leg.

Sciatica is common, and is frequently caused by
lumbar disc herniation(Bickels et al 1999 )
. However, some intraspinal or extra spinal pathologic
processes along the sciatic nerve may also cause sciatica.
Whereas lumbar spine imaging reveals the causes of
intraspinal non-discogenic sciatica (NDS),

Extra spinal sciatica is often misdiagnosed
because routine diagnostic tests focus on the
lumbar spine (Dudeney 1998).
Extra spinal causes affect the nerve as it
progresses distally from the sciatic notch has to
be consider.

 Extra spinal Sciatica (Extra spinal
Radiculopathy)
 Defined as
 Pain, sensory disturbance, or weakness
 by compression or irritation of the left or
right or both sciatic nerves. resulting from
abnormal changes outside the spinal canal

ANATOMY
The sciatic nerve is
the largest nerve of
the body and carries
contributions from L4
to S3.
It passes through the Gluteal region into the thigh, where it divides
into its two major branches common peroneal nerve and the tibial
nerve.

Classification
No clear classification was proposed
Extra spinal causes can
be differentiated into
❖ Diseases of the lumbosacral
plexus and
❖ Lesions of the sciatic nerve
or its branches

Lesions of the lumbosacral
plexus
 usually produce symptoms of more
than one segment, and often the pelvic
condition responsible for lumbosacral
pain overshadows sciatica.
❖ Pelvic tumors (Bickels et al. 1999),
❖ Intrapelvic aneurysm (Dudeney et al.
1998), and
❖ Endometriosis (Dhote et al. 1996).

Lesions of the sciatic
nerve or its branches
 ,
 Pain is not usually a prominent
symptom (Elliott & Schutta
1971).
❖ Compression of the nerve as in
hamstring (Puranen & Orava
1991) and piriformis syndromes
(Hanania & Kitain 1998), or
❖ by vascular compromise as in
diabetes (Naftulin et al. 1993).
❖ A rare cause of sciatica is
cervical and thoracic spinal cord
compression (Ito et al. 1999).

EXTRASPINAL SCIATICA
CAUSES
Kornah
Classification

CAUSES
EXTRASPINALSCIATICA
Outside the nerve
Intra pelvic
Extra pelvic
Within the nerve
Peripheral nerve
entrapment

➢ INTRA PELVIC CAUSES : from neural foramina to greater sciatic
notch
➢ Tumors
➢ Hematoma in the psoas muscle
➢ Gynecological causes > Endometriosis ,Tubo-ovarian abscess
Intrauterine device after uterine perforation
➢ Pyomyositis
➢ Osteophyte at the sacroiliac joint
➢ Sacroiliitis
➢ Anorectal abscess above the levator
➢ Aneurysm (abdominal aortic aneurysm)
CAUSES OUTSIDE THE NERVE

➢ EXTRA PELVIC CAUSES: distal to greater sciatic notch
➢ Piriformis syndrome
➢ Pseudoaneurysm of the Superior Gluteal Artery
➢ Sciatic Nerve Compression by Gluteal Varicosities
➢ Compression of the nerve by wear debris following total hip
replacement
➢ Avulsion fracture of the ischial tuberosity
➢ Tumors
➢ Acetabular paralabral cyst
➢ Surgical Trauma
CAUSES OUTSIDE THE NERVE

CAUSES WITHIN THE NERVE
➢Diabetic Radiculopathy
➢Tumor of neural origin
➢Fibrosis of sciatic nerve

➢Common peroneal nerve
➢Posterior tibial nerve
ENTRAPMENT OF THE PERIPHERAL NERVE

.
Diagnosis of extra spinal
sciatica
 patient history and
 clinical examination
 + Medical history
 Physical signs
 Imaging ( X ray – CT scan ,MRI , US.and
 Magnetic resonance neurography
 Other diagnostic tests NCT+EMG

Symptoms
 INTRA PELVIC CAUSES : from neural
foramina to greater sciatic notch make
irritation to lumbosacral plexus
 Produce symptoms of more than
one segment, and often the pelvic
condition responsible for
lumbosacral pain overshadows
sciatica.

Symptoms
 EXTRA PELVIC CAUSES:
 Distal to greater sciatic notch
 Referred pain is deep, dull, boring and
aching. It follows the distribution of the
myotomes and sclerotomes (Elliott &
Schutta 1971, Bogduk 1997a),

PIRIFORMIS SYNDROME
➢ Piriformis syndrome is a neuromuscular
condition characterized by hip and buttock pain
➢ Delay in diagnosing piriformis syndrome may
lead to pathologic conditions of the sciatic nerve

Piriformis Syndrome Features
1. A chronic nagging ache, pain, tingling,
or numbness
2. starts in the buttocks
3. can extend along the course of the
sciatic nerve
4. down the entire back of the thigh and
calf, and sometimes into the foot
5. Pain worsens when the piriformis is
pressed against the sciatic nerve- (eg,
while sitting on a toilet, a car seat, or a
narrow bicycle seat or while running).

the relationships between
the sciatic nerve and the
piriformis muscle
PIRIFORMIS SYNDROME

1. CLINICAL DIAGNOSIS
A. Clinical symptoms & signs
B. Clinical tests
1. Freiberg sign
2. Pace sign
3. deep digital palpation of the piriformis muscle
PIRIFORMIS SYNDROME

Freiberg sign
Pace sign

Possible Causes of Piriformis
Syndrome
 Anatomical variation
 L/S dysfunction
 Muscle tightness and/or spasm
 Overuse
 Post surgical injury
 SIJ dysfunction
 Trauma/fall

2. Investigations
❑ Plain radiographs
❑ Magnetic resonance neurography
❑ Neurophysiologic testing
PIRIFORMIS SYNDROME

EXTRAPELVIC CAUSES
❖ Pseudoaneurysm of the Superior Gluteal Artery

EXTRAPELVIC CAUSES
❖ Sciatic Nerve Compression by Gluteal Varicosities

Bursitis
IschialTuberosity

Chronic avulsion of the ischial
tuberosity

Compression nerve by wear debris following
total hip replacement
EXTRAPELVIC CAUSES

EXTRAPELVIC CAUSES
TUMORS

Myositis Ossificans hip

Gynecological causes
INTRAPELVIC CAUSES
Hysteromyoma Fluid in Douglas Pouch

Ovarian cyst
INTRAPELVIC CAUSES
Iliopsoas abscess

Osteophyte at the sacroiliac joint
INTRAPELVIC CAUSES

 There are two potential
mechanisms by which Sacroiliitis
can generate sciatica:
 (i) referred pain and
 (ii) direct involvement of the nerve
by inflammatory mediators released
from the sacroiliac joint


 Physical examinations should
include a SI CompressionTest,
 Gaenslen’s test and
 a FABER test.
 The location of the aggravating pain
after the FABER test may reflect the
pathology.

DIABETIC NEUROPATHY
Diabetes may cause a syndrome of severe lower
extremity pain and Weakness. This syndrome usually
involves multiple lumbosacral nerve roots but rarely
presents as a monoradiculopathy. The precise
pathophysiology of diabetic Radiculopathy is controversial
with nerve ischemia, inflammation, and metabolic causes
implicated

TUMORS OF NEURAL ORIGIN
➢ Neurofibroma
Posterior thigh pain, palpable
mass
➢ Schwannoma
Posterior thigh and calf pain
➢ Neurofibrosarcoma
Posterior thigh and calf pain,
known neurofibromatosis

FIBROSIS OF SCIATIC NERVEmay be
❖Post traumatic ,
❖Post injection ,
❖Post inflammatory and
❖Post radiation
which lead to affection of sciatic fibers causing
symptoms of sciatica

ENTRAPMENT OF PERIPHERAL NERVES
COMMON PERONEAL NERVE
traumatic injuries, such as MVA.
location along the thigh down to the
fibular head region
in various forms of trauma, such as
lacerations, femoral fractures, bullet
wounds, and direct injury.
However, most peroneal nerve injuries
occur at the region of the fibular head.

ENTRAPMENT OF PERIPHERAL NERVES
POSTERIOR TIBIAL NERVE
This entrapment typically
occurs within or distal to the tarsal
canal, resulting in pain and/or
sensory disturbance on the plantar
aspect of the foot. Entrapments
above the ankle have been
reported in the popliteal fossa,
where the nerve can be
compressed by the tendinous arch
of origin of the soleus muscle, a
Baker cyst, or other masses that
may occur in this region

Herpes zoster
Skin lesions
along the
trajectories of
the L3 and L4
nerve roots

CONCLUSION
 Sciatica may be caused by extra spinal bone and
soft tissue lesion along the course of the sciatic
nerve.
 Causes of extra spinal sciatica can be within the
nerve or outside the nerve which subdivided into
Intrapelvic causes extra pelvic causes.
 The pain pattern is the key to early diagnosis.
 Special attention should be given to patients with
sciatica that had an insidious onset and is
constant, progressive, and unresponsive to change
in position.

CONCLUSION
 . A detailed patient history, especially
focused on pain characteristics, is an
important component of patient
evaluation. Physical examination of
patients with sciatica should include
inspection, palpation, and all physical
tests to exclude NDS.

Kornah classification
EXTRASPINALSCIATICA
Outside the nerve
Intra pelvic
Extra pelvic
Within the nerve
Peripheral nerve
entrapment

Bahaa Ali Kornah
bkornah@gmail.com

Extra spinal causes of sciatica and a causes algorithm

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