Lumbar spinal stenosis

 Lumbar spinal stenosis perhaps is understood best as a
clinicopathologic disorder: narrowing of the lumbar spinal
canal and the nerve root canals (causing central and
lateral recess stenosis respectively) typically is brought
about by the process of osteoarthritis and leads to
compression of the contents of the canals the neural and
vascular structures, causing neurologic symptoms
(typically low back and leg pain and lower limb
numbness and weakness) that are intermittent,
characteristically triggered by ambulation (ameliorated by
pausing), and generally positional (aggravated by
standing and eased by trunk flexion).

 The emergence of spinal stenosis as a recognizable
disease entity took a major step forward in 1954 with the
work of the Dutch neurosurgeon, H. Verbiest who coined
the term, ‘‘stenosis of the vertebral canal,’’ and defined the
pathologic changes that take place in the lumbar spinal
canal engendered by encroachment of the canal contents
by hypertrophied articular processes.
Although having a narrow lumbar
spinal canal is a necessary component of the condition,
alone it is not sufficient for the disorder
to be expressed, because this requires a degree of
narrowing that compresses canal contents and causes
compromise in sensory and motor nerve
function.

 Accordingly, there may be a poor correlation
between ‘‘stenosis’’ demonstrated by neuroimaging
methods and clinical symptoms.
 Haig and colleagues point out, there is no criterion
standard for the clinical diagnosis of lumbar spinal
stenosis. Clinically, the constellation of symptoms
not always is classic; radiologically, there is no clear
relationship between the severity of symptoms and
degree of stenosis; and electrophysiologically, there
is no predictable, specific electromyographic (EMG)
abnormality.

 Lumbar spinal stenosis is a common problem in adult
life. It is estimated to be present in 5 of every 1000
Americans over age 50.
 It commonly affects adults in their sixth and seventh
decades when it most likely is a result of acquired
degenerative joint diseased lumbar spondylosis.
 A subset of adults in their third and fourth decades
also is affected, and these individuals typically have
congenital narrowing of the lumbosacral spine.

 Some patients who have the congenital form of
spinal stenosis have achondroplastic dwarfism
and at age 38 have a relatively young mean age
of presentation, attesting to the primary nature of
the stenosis.

 The majority of cases of lumbar spinal stenosis,
however, are acquired, and stem from
degenerative or arthritic changes that affect the
three-joint complex between lumbar vertebrae.
 The degenerative process begins most often
with the disk and affects the articular processes
secondarily.
 Spondylolysis (a defect in the pedicles, the
parsinterarticularis -congenital or acquired) may
lead to spondylolisthesis, the anterior
displacement of one vertebra relative to the one
beneath it, further narrowing an already stenotic
lumbar canal.

on the basis of the location of neural
compression.
 - central,
 - lateral recess,
 - foraminal

Central canal stenosis
o With aging, occurs as degenerative changes
progress.
o As the axial height of disc & facet jts decreases,
disc bulges into spinal canal.
o Central canal is further narrowed by posterior
impingement from enlarged facets & hypertrophied
ligamentum Flavum.
o Hypertrophy of the soft tissues is responsible for
40% of spinal stenosis
o With extension, the hypertrophied ligamentum
buckles centrally into the canal and worsens the
central stenosis.
This explains why patients with
stenosis typically report worsening of their
symptoms in extension.

Lateral recess stenosis
 Typically results from posterior disc protrusion in
combination with some superior articular facet
hypertrophy.
 Lateral recess stenosis can present with lumbar
radiculopathy; incidence of lateral recess stenosis
ranges from 8% to 11%.
Foraminal stenosis
 causes compression of the exiting nerve root and
ganglion and leads to lumbar radiculopathy.
 occurs most commonly in the lower lumbar spine, with
the L5 nerve root being the most commonly involved.
 can occur from loss of disc height, vertebral endplate
osteophytes, facet osteophytes, spondylolisthesis, and
disc herniations

Lee et al. classification
 Nerve root canal into three zones to clarify the
anatomy and to describe the pathologic
structures responsible for nerve root
compression within the three zones:
1. lateral recess,
2. foraminal,
3. extraforaminal stenosis

 Patients present with the insidious onset of diffuse, often symmetric
symptoms, reflecting the bilateral nature of the underlying disease
process that often involves several vertebral levels.
 The first symptoms of lumbar spinal stenosis frequently are low back
pain and morning stiffness relieved by activity.
 As time passes, there frequently is low back, buttock, thigh, and calf
discomfort, often described as a cramping, burning sensation,
sometimes with associated numbness and tingling in the legs and
thighs.
 Weakness is not a prominent symptom but may be present, most often
manifested as partial foot drop or weakness in plantar flexion,
especially after prolonged standing or walking, and pointing to the
common involvement of muscles served by L5 and S1 roots.

 A characteristic of the symptoms produced by lumbar spinal
stenosis is that they are induced or triggered by standing and
walking (activities that extend the lumbar spine) and eased by
sitting or flexing the trunk.
 The latency from the start of standing to the onset of pain varies
from patient to patient and also changes over time for individual
patients, becoming shorter when and if the disease process
evolves.
 A classic clinical feature of lumbar canal stenosis is neurogenic
claudication, the dynamic phenomenon of standing- and walking-
related symptoms (thigh or leg pain preceding numbness and
motor weakness), causing patients to limp and then to cease the
provocative activity.

 It is to be distinguished from the vascular mechanism
encountered more commonly underlying painful legs,
induced by walking, in the context of atherosclerotic
peripheral vascular disease.
 In this vascular disorder, the typical history is that cramping
develops in the calves with activity (such as walking,
cycling, or descending, and especially ascending, stairs)
and that relief is obtained by sitting and resting.
 In neurogenic claudication, by contrast, ascending stairs
typically is less likely to induce symptoms than descending,
probably because the former allows for a partially flexed
trunk, whereas in the latter, the lumbar spine straightens
out, obliging patients to walk downstairs backward to adopt
a forward-flexed position ,cycling is tolerated much more
than walking.

 In the early stages of the disorder, the symptoms may be mild
and provoked after an extended period of standing or
walking, but as time passes, the disease seems to enter an
extended plateau phase in many patients.
In others, symptoms may become more
pronounced and diffuse, triggered by only brief periods of
standing, reaching the point where quality of life may become
seriously compromised. In these advanced cases, patients
barely are able to walk short distances without severe
symptoms and reflexively attempt to attenuate any discomfort
by using a stooped or anthropoid posture (effectively flexing
the back) that presumably allows for widening of the lumbar
spinal canal .
 In approximately 10% of patients, generally those who have
the most advanced degrees of lumbar spinal stenosis, there
are symptoms of bladder control difficulties, manifested as
recurrent urinary tract infections associated with an atonic
bladder, incontinence, and, rarely, episodes of urinary
retention.

 The examination findings are muted, in contrast to the findings in
lumbosacral radiculopathy (which may coexist with lumbar spinal
stenosis).
 In lumbosacral radiculopathy, there is straight leg raising and
reverse straight leg raising positivity, segmental weakness,
attenuation of reflex activity, and dermatomal sensory loss.
 In lumbar spinal stenosis, there may be flattening of the lumbar
lordosis and a decrease in lumbar extension. Positive straight leg
raising complaints of a severe sciatica-like pain in a raised leg at
30 to 40 of elevation is uncommon in patients who have lumbar
spinal stenosis.

Provocative measures suggestive of lumbar spinal stenosis
include lying prone in lumbar hyperextension, walking, and
walking with an exaggerated lumbar lordosis until symptoms
appear, followed by relief of symptoms by leaning forward .

 At rest there may be a paucity of findings , but with onset
of symptoms after walking or extending the spine, there
may be diminution in patellar and Achilles tendon reflexes,
mild sensory loss in L4 to S1 dermatomes, and mild
weakness in L4-, L5-and S1 innervated muscles hence,
the importance of the stage advice from Alvarez and Hardy
to perform a neurologic examination before and
immediately after symptoms appear after a short period of
ambulation.

 Three explanations are advanced to explain the
phenomenon of neurogenic claudication, the cardinal
manifestation of lumbar spinal stenosis.
 They are designated the postural, the ischemic, and the
venous stasis (stagnant hypoxia)theories.
 The postural theory suggests that symptoms are
explained by transient compression of the cauda equina
(leading to sensory and motor axon dysfunction) by
degenerated intervertebral disks and thickened
ligamentum flavum, when the lumbar spine is extended
and lordosis is accentuated, either at rest or in the erect
posture.

 In the ischemic theory, it is proposed that the
metabolic demand of the cauda equina cannot be
met during activity (eg, walking), that blood flow
needs of the lumbosacral nerve roots are not met
by the local vasculature that is compromised by
lumbar spinal stenosis.
 Porter suggested the venous stasis theory: that the
underlying mechanism of neurogenic claudication
is inadequate oxygenation or the accumulation of
metabolites in the cauda equina.

 A good physical examination of patients with lumbar
spinal stenosis should start with observation.
 Often, these patients will be sitting flexed forward on a
chair in the examination room.
 While standing & ambulating, stenosis patients still
often flex their trunk forward to decrease their
symptoms.
 ROM shows decrease in the active lumbar extension.

 Reproduction of the patient’s usual symptoms
by prolonged lumbar extension can also be
helpful in confirming the diagnosis.
 Neurologic examination is often normal in spite
of long-standing debilitating symptoms.
 Lateral recess stenosis is more commonly
responsible for neurologic changes.
 When motor weakness or sensory deficit is
present, it is most often in the L5 distribution.

 A frequent neurologic finding is an asymmetrical deep tendon
reflex at the patellar or Achilles tendon.
 A symmetrical decrease in the reflexes is more indicative of age-
related changes.
 Nerve root tension signs are usually not present.
 Changes in neurologic examination may become more obvious
after stressing the patient’s neurologic system.
This can be accomplished by
asking the patient to walk until Patient experiences significant
symptoms.
 Reexamination at this point may reveal changes in motor, sensory,
or reflex examination that were not detected before the stress.

 Amundsen & colleagues prospectively evaluated the
clinical and radiographic features of 100 patients with
symptomatic spinal stenosis.
 They reported a motor weakness in 23% and sensory
deficit in 51%.
 In the 2007 randomized controlled trial of 94 stenosis
patients from the Finnish Lumbar Spinal Research
Group,
 22% of patients had an L5 motor weakness and 19%
had a sensory deficit.
 SLRT was positive in 3% of the patients.

 In the recent SPORT study,
 asymmetrical reflexes were noted in 26%,
 motor weakness was noted in 28%,and sensory deficit was noted
in 29%.

 Diagnostic testing of patients with spinal stenosis
often starts with plain radiographs.
 In addition to the AP & lateral radiographs, flexion &
extension lateral views should be obtained.
 Prior to the common availability of MRI, a CT scan
was the study of choice for visualizing pathologic
anatomy in the axial plane. Because a significant
portion of the stenosis comes from soft tissue
pathology, visualization of the soft tissues is the top
priority in axial imaging.

A CT scan is a poor modality
for detailed analysis of the
soft tissue pathology.
A metaanalysis demonstrate
that the sensitivity of a CT
scan in detecting spinal
stenosis ranges from 70% to
100%.
Soft tissue window of a
computed tomography scan
through the L4–L5 level
demonstrating stenosis

• Diagnostic utility of the CT scan can be improved by combining
it with myelography
• Dye injected in CSF during a myelogram provides good
contrast b/w thecal sac & surrounding soft tissue and bony
pathology.
• Preoperative complete contrast block on a CT-myelogram
has been correlated with an improved surgical outcome.
• Invasiveness of the myelogram and the radiation associated
with the CT are the two biggest drawbacks of this diagnostic
modality.

 Given these limitations, patients who are unable to
have an MRI, who have scoliosis, or who have
previous spinal instrumentation are the most likely
to undergo this study.
Myelogram of a patient
with neurogenic
claudication who had a
h/o a previous lumbar
instrumented fusion.

• Boden et al. noted abnormal findings in 67% of
asymptomatic patients evaluated by MRI.
• In patients older than 60 years, 57% of MRI scans were
abnormal, including 36% of patients with herniated
nucleus pulposus, and 21% with spinal stenosis.
• Hence, findings of MRI should be matched with the
symptoms and signs of patients having neurogenic
claudication or radiculopathy.

• Electromyography (EMG),
• nerve conduction studies (NCSs), &
• somatosensory evoked potentials (SSEPs)
are not part of the routine workup of
patients with spinal stenosis.

 Vascular Claudication
 Lumbar Spondylosis,
 Lower Extremity Arthritis,
 Cord Compression,
 Neurologic Disorders,
 Peripheral Neuropathy,
 Infection,
 Tumors, And
 Lumbosacral Plexus Lesions.

 the investigators pointed out that an initial
conservative approach seems advisable for many
patients, because those who have initial
unsatisfactory results still can be offered surgery with
a good outcome at a later date.
 In light of the report and the observation that surgical
intervention may be associated with significant
increased morbidity, surgical complications, and
mortality, it seems appropriate to offer conservative
management to patients experiencing mild to
moderate symptoms when symptoms are not
progressive and when work and leisure activities are
not hampered seriously.
 Controlled trials examining the outcome of
conservative management, however, are lacking.

 Exercises may include use of an exercise
bicycle and brief walks (encouraging walking
with a rolling walker to promote a pain-
alleviating flexed posture).
 In addition, patients should avoid lumbar
extension exercises, consider the occasional
use of lumbar bracing, and adopt a weight loss
program if obese.
 Other treatments of unproved or anecdotal
value include medications, such as nonsteroidal
anti-inflammatory drugs and muscle relaxants,
transcutaneous nerve stimulation and
ultrasound therapy, and periodic courses of
epidural corticosteroid injections.

 For some individuals, conservative measures fail to
provide adequate relief from severe symptoms of
neurogenic claudication that may reach the point of
compromising quality of life. In such cases, it is
appropriate to consider surgical intervention, even in the
geriatric population, to improve walking tolerance and
ease disabling leg and back pain.
 Surgical options include multilevel decompressive
laminectomies (because canal stenosis occurs
commonly over several levels),unilateral decompressive
hemilaminectomy, and multilevel laminotomies, whereby
fenestrations are created by removing portions of the
lamina of adjacent involved vertebrae, preserving
spinous processes, and sparing interspinous ligaments.

 The goals of surgical intervention are pain relief,
increased mobility, preservation of neural tissue,
and prevention of increasing clinical deficits.
 In a systematic review of preoperative predictors
for postoperative clinical outcome (level of pain) in
lumbar spinal stenosis, depression, coexisting
cardiovascular comorbidity, poor walking
(resulting from joint athritis, neurologic disease,
cardiopulmonary disease), and scoliosis predict
poorer subjective outcome (worse postoperative
pain).
 Better subjective outcome is predicted by factors,
such as better walking ability, self-rated health,
higher income, less coexisting disease, and
pronounced central stenosis.

Lumbar spinal stenosis

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Lumbar spinal stenosis