Lumbar Disc Herniation

Dagan Cloutier, PA-C within the cauda equina and exit the neural foramen
New Hampshire Orthopaedic Center, Nashua, NH under the corresponding pedicles. For example, the
L5 root traverses below the L4–L5 disc level and
Lumbar disc herniation is the most common exits laterally under the pedicle of L5. The S1 nerve
surgical condition in patients presenting with root traverses below the L5–S1 disc level and exits
radicular leg pain, with approximately 200,000 laterally under the pedicle of S1.
patients undergoing operative treatment each
Disc herniation can be classified by location
year.1 Lumbar herniated nucleus pulposus (HNP)
into three anatomical zones of the spinal canal:
presents symptomatically with a sudden or
central, paracentral, and foraminal. The central zone
insidious onset of unilateral leg pain and is usually
lies between the lateral borders of the cauda equina.
associated with an injury or precipitating event
The paracentral or posterior lateral zone extends
(often a forward bend and lifting maneuver, during
from the lateral border of the cauda equina to the
which intradiscal pressure is high). Patients may
medial border of the pedicle. The foraminal zone
also complain of intermittent back pain for months
lies between the medial and lateral borders of the
or years, with a recent aggravating event that
pedicle. Extraforaminal disc herniations are located
worsens symptoms.
lateral to the border of the pedicle. Posterior to the
Radicular pain usually extends below the disc space is the posterior longitudinal ligament
knee and follows a dermatomal pattern, correlating (PLL). The PLL is an hourglass-shaped ligament, with
with the nerve root involved. With lumbar disc the widest part located at the midline and thinning
herniation, symptomatic leg pain is more severe bands extending laterally. The superior lateral disc
and frequent than low back pain. Standing, is left uncovered by the PLL, which explains why this
prolonged sitting, and Valsalva maneuvers can location is the most common site of disc herniation.
aggravate the pain. Lumbar HNP usually affects
The location of the disc herniation will
young and middle-aged adults, with a peak in those
determine which nerve root is affected. Posterior
35 to 45 years of age. As the nucleus pulposus ages,
lateral disc herniations generally affect the nerve
it loses water content and desiccates, and is less
root at the traversing level. The less-common lateral
likely to herniate after the fifth decade of life.
recess and foraminal disc herniations affect the
Anatomy
Intervertebral discs consist of the nucleus
pulposus, a firm, rubbery tissue that is surrounded
by the ligamentous anulus fibrosus. Axial
compression forces are transmitted to the nucleus
and sustained circumferentially by the anulus. The
nucleus pulposus lacks blood supply and nerve
innervation, and relies on nutrients and oxygen
that diffuse from the anulus fibrosus. Consequently,
any injury to the nucleus pulposus will not heal.
The anulus contains nerve innervation and
may cause lower back pain with injury. The anulus
also contains a blood supply that allows scar
formation and healing after injury. Any disruption
of the anulus can result in herniated disc tissue due
to axial compression forces of the spine. Discs in FIGURE 1 Posterior Longitudinal Ligament.
The red oval shows the location of a posterior
younger adults are well hydrated and more likely
lateral disc herniation.
to herniate. Lumbar roots below L1 are contained

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Table 1. Exam Findings in Lumbar Disc Disease
Level of HNP Root affected Motor strength Sensation Reflex
L1-L3 L2, L3 Hip Flexors Anterior thigh None
L3-L4 L4 Tibialis anterior Medial ankle Patella
L4-L5 L5 Extensor hallucis Dorsum of foot None
longus
L5-S1 S1 Gastroc/Soleus Posterior calf, plantar Achilles
foot
S2-S4 S2, S3, S4 Bowel/Bladder Perianal Cremesteric

exiting nerve root at the affected level. For instance, Exam

an L4–L5 posterior lateral disc herniation would Exam begins with observation of the
affect the L5 nerve root. A foraminal herniation at patient’s pain level and any postural changes. Pain
that L4–L5 level would affect the L4 nerve root. The can worsen when disc space pressure increases
majority of herniations occur in the L4–L5 and L5– during activities like walking, sitting, and standing.
S1 levels. Lying reduces disc space pressure and usually
improves pain. The patient often cannot sit still
Pathology and constantly changes positions in an effort to
Disc herniations can be classified as find a more comfortable position.
protrusion, extrusion, or sequestered. Disc
protrusion (or disc bulge) is a symmetrical bulge A complete neurological exam is necessary
around the circumference of the anulus, leaving and should include testing of lower extremity
the anulus intact. Disc protrusion may or may not motor strength, sensation, and reflexes. Muscle
impinge on a neurologic structure. The resulting group weakness may be evident at presentation or
pressure from the disc bulge on the innervated several weeks after herniation occurs. Sensation is
anulus can cause a significant amount of lower decreased almost immediately along a dermatomal
back pain, which is often referred to or diagnosed pattern, correlating with the insulted nerve. Deep
as discogenic back pain. A disc extrusion extends tendon reflexes are often depressed or absent in
through an anular tear, but is still in partial the affected muscle group. Provocative testing
continuity with the parent disc. An anular tear should be performed last because it will likely
can cause significant back pain when it occurs, illicit pain. Straight-leg raise of the involved leg
but after the pressure is relieved, the back pain and the uninvolved contralateral leg may both
usually subsides. A sequestered disc herniation illicit radicular pain. Radicular pain in the involved
is a fragment free from the parent disc within leg with straight-leg raise of the uninvolved leg
the spinal canal and prone to proximal and distal is specific for herniation. Back pain alone with
migration, usually only 1 or 2 cm. straight-leg raise is not a positive finding. Clinical
findings of pain, decreased motor strength, and
Spinal nerve root compression from HNP can sensation are correlated with the nerve root
cause moderate to severe radicular pain, decreased affected (Table 1).
sensation, and motor weakness. However, nerve
root compression from the disc pathology is not A vascular exam, including palpation of
always symptomatic. Lumbar MRI commonly dorsalis pedis and posterior tibialis arteries,
reveals asymptomatic disc pathology. Fewer should be performed. Vascular and neurogenic
than 6% of lumbosacral disc herniations become claudication can cause leg pain and reduced
symptomatic.2 Symptomatic herniations are not walking capacity. Neurogenic claudication has a
always a result of direct neurologic compression. gradual progression of symptoms compared to
Chemical nerve root irritation plays an important lumbar HNP and is more often caused by spinal
role in radicular pain. Acute herniated disc material stenosis and degenerative spondylolisthesis.
triggers the release of arachidonic acid and other Patients with spinal stenosis often complain
inflammatory mediators that encounter the nerve of worsening pain with spinal extension and
root, causing irritation.1 significant relief with flexion, whereas herniated

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 FIGURE 2 Sagittal view of L5-S1 disc herniation FIGURE 3 Axial view of left posterior lateral
disc herniation

disc patients have more pain with spinal flexion instrumentation.

and relief with extension.
Gadolinium-enhanced MRI should be
Testing for ankle clonus and Babinski’s will performed in patients with a history of previous
help rule out upper motor neuron pathology. Hip level surgery or when recurrent disc herniation
and pelvic pathology can cause referred pain is suspected. Contrast enhancement helps
to the back and lower extremities. Differential differentiate disc herniation from postoperative
diagnoses that should be considered include hip scar tissue causing neural impingement.
osteoarthritis, iliotibial band syndrome, meralgia Electromyography can help differentiate radicular
paresthetica, inguinal hernias, and sacroilitis. symptoms from peripheral neuropathy or upper
Obtaining a detailed history and performing a motor neuropathy. Any presentation of urinary
complete physical exam of the hip and lower retention, urinary or fecal incontinence, saddle
extremities will help establish the diagnosis. anesthesia, and bilateral radicular symptoms
should raise concern of possible cauda equina
Antero-posterior and lateral radiographs
syndrome (CES).
are initially taken to check for spondylolithesis,
fracture, and foraminal stenosis. MRI is the
diagnostic study of choice, as it clearly delineates
Cauda equina syndrome (CES)
size, type, and location of a disc herniation. An CES occurs in only 2% of lumbar HNPs
MRI can differentiate other causes of radicular and is usually caused by a large central lumbar
pain, such as primary tumor or metastatic disease disc herniation. The cauda equina includes the
and bony compression. Symptoms of night pain peripheral nerve roots L1–S5 located within the
or previous history of cancer should warrant MRI, dural sac. Compression of these roots causes
even in the case of negative initial radiographs. symptoms of a lower motor neuron lesion, such
Computed tomography myelography can be used as muscle weakness, decreased sensation, and
when MRI is contraindicated, such as in patients decreased or absent reflexes.
with pacemakers. This form of imaging is also Onset of symptoms can be rapid or slowly
helpful in patients with prior spinal surgery with progressive. Symptoms unique to CES include

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perigenital, perirectal, or “saddle” anesthesia injections deliver fluid into the posterior epidural
and loss of bowel or bladder control. Bladder compartment, with hope that it will flow to the
dysfunction is a required symptom for diagnosing insulted nerve root.4 Transforaminal approaches
CES. Motor loss can start with subtle difficulty require fluoroscopic guidance for safe and accurate
initiating the urinary stream with progression placement.
to urinary retention and eventual overflow
Butterman reported on the efficacy of
incontinence. Decreased rectal tone can be an
treatment with ESIs in surgical candidates with
early sign of CES, and a rectal exam is important
lumbar disc herniation. Nearly one-half of the
in establishing the diagnosis. Preferable treatment
patients who received ESIs had a decrease in
is decompression via discectomy within 24 h of
symptoms. The degree of improvement was
symptoms to prevent progression of neurological
similar to the results seen in patients who
deficits. Although timing of surgery is still under
underwent discectomy. The study also reported
debate, evidence shows that there is a significant
that delaying surgery for an initial trial period of
difference in the resolution of motor and sensory
ESIs was not detrimental to neurological recovery.5
deficits postoperatively with treatment within 48
Contraindications for ESIs include local or systemic
h.3
infection, anticoagulation, contrast dye allergy,
and previous spine surgery at that level.
Treatment
Herniated lumbar discs affect 2% of the Spine Patient Outcome
population. Seventy-five percent of these patients
are asymptomatic after 6 weeks, and 90% are Research Trial (SPORT)
symptom-free at 3 months. Resolution of motor The Spine Patient Outcome Research Trial
weakness is seen with 80% of patients after 6 weeks, (SPORT) was a prospective, multicenter study
90% after 12 weeks, and 93% after 24 weeks.2 funded by the National Institutes of Health that
The natural history of lumbar disc herniation examined surgical vs. non-surgical outcomes for
is eventual disc resorption and resolution of intervertebral disc herniation, spinal stenosis, and
symptoms. Conservative care with rest and anti- degenerative spondylolisthesis. SPORT was one of
inflammatory medications are initiated early. A the first comprehensive studies of the efficacy of
Medrol DosePak, which can include a 6-day tapering surgery for lumbar disc herniation. The variable
course of 4 mg methylprednisolone with six tablets discectomy rates within regions of the United
on the first day and one tablet on the last day, is States and the lower rates seen internationally
commonly prescribed. Patients should be advised raise concern about the appropriateness of
that there is less than a 10% chance of significant surgical decision-making. SPORT was designed to
symptoms beyond 3 months. Physical therapy address these concerns and provide information
should be started to strengthen core muscles when on how to best treat lumber disc herniation.
symptoms tolerate. Transcutaneous electrical Candidates from 13 spine clinics across 11
nerve stimulation (TENS) units are commonly used states with image-confirmed lumbar disc herniation
in the therapy setting for pain relief. Narcotics and were randomized into one of two groups: operative
muscle relaxers are used cautiously to prevent treatment and non-operative treatment. Patients
dependence. included 501 surgical candidates with image-
Lumbar epidural steroid injections (ESIs) confirmed lumbar disc herniation and persistent
have increasingly been used as a low-risk signs and symptoms of radiculopathy for at least
alternative to surgical intervention for patients 6 weeks. Weinstein et al. reported that patients
who failed conservative treatment. Steroids in both the operative treatment group and non-
inhibit the inflammatory response caused by disc operative treatment group improved substantially
chemical irritation and mechanical compression. over a 2-year period. Due to the large patient
Common injection techniques include interlaminal crossover between treatment groups, the intent-
and transforaminal approaches. Transforaminal to-treat analysis showed no statistically significant
injections target the anterior epidural space differences between the two groups. Although
closest to the nerve root pathology. Interlaminal not significant, differences in improvements were

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consistently in favor of surgery for all outcomes physical signs and symptoms. Timing of surgery is
and at all time periods. The pattern of crossover a source of ongoing debate. Peul et al. reported that
between treatment groups suggested the intent- early surgery after a failed conservative treatment
to-treat analysis underestimated the true effect of period of 6 weeks offered significant benefits over
surgery.6 non-operative treatment in the early follow-up
period. The maximum surgical benefit was seen at
In 2008, Weinstein et al. reported on results
8 to 12 weeks postoperatively. However, at years
between groups at 4 years. Patients who underwent
1 and 2, no differences existed between operative
surgery achieved greater improvement than the
and non-operative groups in primary outcome
non-operatively treated patients in all primary and
measures.10 Therefore, patients should be educated
secondary outcomes except for work status.7
on the benefits of surgery in the short-term, as long-
Several other studies based on the SPORT data term benefits are less proven. A patient’s treatment
have been published. Radcliff et al. investigated preference may be influenced by factors such as
the effect of ESIs on primary outcome scores and the desire to return to work, litigation involvement,
how ESIs influenced operative vs. non-operative Workers’ Compensation, and psychological issues.
treatments. Results showed no significant All factors should be considered when determining
differences in outcome scores between patients the most appropriate treatment choice for each
who received ESIs and patients who did not at patient.
years 1, 2, 3, and 4. However, the study showed an
Lumbar discectomy has been performed
increased rate of surgical avoidance in the group
for over 70 years and open microdiscectomy is
who received ESIs. The study reported a 41% rate
the most common technique performed today.
of crossover by surgically assigned patients who
Minimally invasive procedures attempt a smaller
received ESIs, compared to a 12% rate of crossover
incision, limited foraminotomy, and removal of
by surgically assigned patients who did not receive
displaced disc tissue. The most common approach
ESIs.8
to the lumbar spine for lumbar discectomy is a
Rihn et al. examined symptom duration and posterior midline approach. The patient is placed
how timing of treatment influenced outcome. The in a prone position on a radiolucent table (such
study concluded that increased symptom duration as a Jackson or Andrew’s table). Preoperative
beyond 6 months due to lumbar disc herniation and intraoperative radiographs or fluoroscopic
was related to worse outcomes for patients in images are taken to guide the surgical approach to
both the operative and non-operative groups. The the correct level of pathology. The most common
increased relative benefit of surgery compared to complaint in litigation cases against spine surgeons
non-operative treatment was independent of the is wrong-level surgery, so identifying the correct
duration of symptoms.9 level of pathology before and during the surgical
approach is essential.
Operative Treatment After the correct level is confirmed, a
The main surgical indication for lumbar disc standard laminotomy or partial laminectomy is
herniation is unremitting radicular pain. Motor performed to adequately visualize the pathology.
weakness caused by lumbar disc herniation will Gentle retraction of neural elements will allow
resolve in most cases and is not an indication for visualization of the disc material for removal.
surgery. Only when motor weakness is disabling An anulotomy or incision through the posterior
and associated with severe pain or progresses longitudinal ligament and anulus fibrosis can be
rapidly is surgery indicated. There is no evidence performed to access remaining herniated disc
to support that surgery improves the recovery of tissue. A dose of 1 ml DepoMedrol® (80 mg) may
motor weakness better than conservative care in the be applied to the affected nerve root for further
short-term or long-term. Residual motor weakness postoperative relief prior to closure.
postoperatively is correlated with the severity and
Patients are often admitted postoperatively
duration of motor symptoms preoperatively.2
for observation overnight, but surgery is also
MRI will confirm the level and location of disc performed in outpatient settings. Patients generally
herniation, which should correlate with the patient’s experience improvement or resolution in leg pain

20 JOPA
within 24 hours and often wake up from surgery
with dramatic relief. Any postoperative headache
should raise concern of a dural tear; patients Authors have no relationship to disclose relating to the
with these complaints should be kept supine until content of this article

symptoms improve. References

1. Lee JK, Amorosa L, Cho SL, Weidenbaum M, Kim Y. Recurrent lumbar disc herniation. J
Activity includes slow progressive walking Am Acad Orthop Surg. 2010; 18(6): 327-37.
2.Sharma H, Lee SW, Cole AA. The management of weakness caused by lumbar and
and activities of daily living as tolerated, starting lumbosacral nerve root compression. J Bone Joint Surg Br. 2012; 94(11):1442-7.
3.Darden B, Kim D, Madigan L, Rhyne A, Spector LR: Cauda equina syndrome. J Am Acad
immediately. The patient should be educated on Orthop Surg. 2008; 16(8):471-9.
4.IA, Hyman GS, Packia –Raj LN, Cole AJ: The use of lumbar epidural/transforaminal steroids
postoperative restrictions, including no bending or for managing spine disease. J Am Acad Orthop Surg. 2007; 15(4): 228-38.
lifting over 10 lbs and no twisting. Physical therapy 5.Butterman GR. Treatment of lumbar disc herniation: epidural steroid Injection compared with
discectomy. A prospective, randomized study. JBJS 2004; 86(4): 670-9.
for core strengthening may begin anywhere 6.Weinstein JN, et al: Surgical vs nonoperative treatment for lumbar disc herniation. The
Spine Patient Outcomes Research Trial (SPORT) A Randomized Trial: JAMA. 2006; 296(20):
between 2 and 6 weeks, with extension exercises 2441-2450.
7.Weinstein JN, et al: Surgical versus nonoperative treatment for lumbar disc herniation: four
encouraged initially. Long car rides and heavy year results from the Spine Patient Outcome Research Trial (SPORT). Spine. 2008; 33(25):
lifting should be avoided for 3 months. Success 2789-2800.
8.Radcliff K, et al. The impact of epidural steroid injections on the outcomes of patients treated
rates including pain relief from surgery are greater for lumbar disc herniation A subgroup analysis of the SPORT Trial. JBJS. 2012; 94(15): 1353-8.
9.Rihn JA, et al. Duration of symptoms resulting from lumbar disc herniation: Effect on
than 90%. Recurrent herniation, as defined by treatment outcomes analysis of the Spine Patient Outcomes Research Trial (SPORT). JBJS
2011; 93(20): 1906-14.
herniation after a pain-free period of 6 months, can 10.Peul WC, Arts MP, Brand R, Koes BW. Timing of surgery for sciatica: a subgroup analysis
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Image Quiz Answer

Answer: C. AP and lateral radiographs (Figures 1 and 2) show a left greater trochanteric fracture. Isolated
fractures of the greater trochanter usually result from direct impact. Controversy exists as to the best way to treat
isolated greater trochanteric fractures. It is difficult to establish a definitive diagnosis when plain films cannot rule
out a possible occult fracture extension. CT or MRI should be considered to rule out fracture extension; if negative,
immediate weight-bearing as tolerated can be initiated. Follow up radiographs should be obtained to monitor for
displacement secondary to the pull of the gluteus medius and gluteus minimus muscles.

FIGURE 3 CT image of the left hip. No fracture FIGURE 4 CT image of the left hip showing the
extension is seen through the isolated greater trochanteric fracture.
trochanteric region.

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