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74 Spine Core Knowledge in Orthopaedics
●
Results of thoracic discectomy are generally good, in
terms of both pain relief and recovery of motor function
in those patients with myelopathy (Bohlman et al. 1988,
Simpson et al. 1993).
●
The overall complication rate for thoracic discectomy is
15% (Stillerman et al. 1998).
●
Major—Death, permanent neurological deterioration,
medical complications, need for reoperation
●
Minor—Neuralgia, pneumothorax, continued pain,
wound infection
Lumbar Spine
●
A symptomatic lumbar disk herniation occurs during the
lifetime of 2% of the general population.
●
Risk factors for sustaining a lumbar herniated disk
include the following:
●
Male gender
●
Age 30-50
●
Heavy lifting, especially in a twisting motion
●
Poor job satisfaction or low income
●
Cigarette smoking
●
Prolonged vibration exposure
●
Of lumbar disk protrusions, 90%-95% are observed at the
L4-L5 or L5-S1 level.
●
Not all disk pathology has clinical importance
(Table 6–8).
Figure 6–9: Radiograph showing thoracic disk calcification.
Figure 6–10: CT myelogram revealing a herniated thoracic
disk.
Clinical Presentation
●
Usually, in mild or moderate disk herniations, patients
first notice lower back pain corresponding to anular
pressure and fissuring.
●
This can progress to frank tears in the anulus and
herniation of inflammatogenic material; the severity of
the lower back pain may lessen, but a radiculopathy in
the form of pain, paresthesia, or weakness can appear
because of pressure on the nerve root.
●
With severe herniations, the patient may experience
immediate lower extremity pain with little or no lower
back involvement.
●
Lower back pain will be intermittent and is often
brought on by physical activity and made worse by
prolonged sitting, moving from a seated to a standing
position, or bending and twisting (each of these
movements increases lumbar disk pressure).
●
In patients experiencing herniation of lumbar disks with
radiculopathy,Valsalva maneuvers may exacerbate pain in
the lower extremity (Box 6–8).
Diagnosis–Clinical Exam
●
Posture—Standing (sitting hurts); a possible spasm causes
a pseudoscoliotic list to one side or a straightening of the
lumbar lordosis.
CHAPTER 6 Herniation of the Nucleus Pulposus in the Cervical, Thoracic, and Lumbar Spine 75
Table 6–7: Surgical Approaches for Thoracic Disk Herniations
SURGICAL APPROACH VARIATIONS INDICATIONS ADVANTAGES DISADVANTAGES
Anterior Transsternal Central or centrolateral disks Excellent midline exposure Violates pleura
Thoracotomy or Transsternal T1-T4 Multiple levels accessible Significant perioperations
transthoracic T4-T12 rib resection or Facilitates instrumentation Morbidity
Detachment of diaphragm rib-splitting Diaphragm takedown
for access to lower levels significantly slows recovery
Posterior Laminectomy (abandoned) Lateral, some centrolateral Avoids morbidity of Limited visualization of disk
Pediculofacetectomy disks thoracotomy Access not possible to
Transfacet pedicle-sparing Upper thoracic spine midline or intradural disks
Higher incidence of segmental
instability, pain
Lateral Extracavitary Lateral or centrolateral disks Pleura is not violated—less Technically difficult
Costotransversectomy morbidity, etc. Relatively large posterior
Diaphragm remains intact dissection
Complete anterior decompression
is difficult
Video-assisted Conversion to open Lateral or centrolateral disks Avoids morbidity of Increased operative time
thoracoscopic surgery always possible thoracotomy Steep learning curve
Avoids posterior muscle, Limited decompression, no
bone dissection ability to instrument
Shorter ICU stays, High incidence of intercostal
rapid recovery neuralgia or visceral injury
Box 6–7:
●
Anatomy
●
Rib cage stability may make fusion unnecessary
●
Relative indications
●
Scheuermann’s kyphosis patients (prone to further kyphosis)
●
Lower levels (rib cage stability not present)
●
Partial corpectomy performed to access disk
●
Multiple levels removed
●
Advantages
●
Low morbidity, easy to perform
●
Increases stability to prevent collapse (controversial)
●
Disadvantages
●
Requires bone graft (autograft or allograft) unless rib can be
Role of Arthrodesis in Thoracic Disk
Herniations
used
●
Slightly longer operative time
●
Instrumentation (used almost exclusively for lower levels)
●
Increases cost and operative time
●
Provides stability at a high-stress junctional zone
Table 6–8: Abnormal Lumbar Disk MRI Findings in
Asymptomatic Subjects*
AGE HERNIATED DISK BULGING DISK DEGENERATED DISK
20-39 21% 56% 34%
40-59 22% 50% 59%
60-80 36% 79% 93%
* (Boden et al. 1990b.)
●
Heel and toe gait should be observed to detect weakness
of L5 or S1 (see Figs. 6–11 and 6–12).
●
Tension signs are useful in diagnosing a lumbar disk
herniation; a straight leg raise (SLR) in patients under 35
is specific and sensitive to a symptomatic disk herniation.
●
Maximal tension is created in the sciatic nerve and
transmitted to the nerve roots between 35 and 70 degrees
of leg elevation.
●
For a true, positive SLR, patients should experience
radicular pain or paresthesia below the knee within the
leg elevation range above (Fig. 6–11).
Box 6–8:
●
Typically large midline herniations in older patients with spinal
stenosis
●
1-2.4% of symptomatic lumbar disk herniations
●
Symptoms or signs
●
Bowel or bladder difficulties
●
Saddle anesthesia
●
Diminished rectal tone
●
Lower extremity sensory and motor deficits
●
Should be treated as a surgical emergency; decompression within
48 hours provides best outcome
* (Ahn et al. 2000.)
Lumbar Disk Herniation and Cauda
Equina Syndrome*
76 Spine Core Knowledge in Orthopaedics
Figure 6–11: L5 nerve root functions.
●
Femoral stretch testing (performed by extending the hip
with a bent knee and with the patient prone) can
reproduce radicular pain from compression of a higher
lumbar root (L2-L4).
●
The following Waddell signs should be noted:
●
Nonanatomic distribution of pain or tenderness to
light touch
●
Low back pain when standing with a downward force
on the head
●
Change in findings with posture, distraction, etc. (e.g.,
SLR)
●
Overreaction or symptom magnification
Motor and Sensory Examination
●
See Figs. 6–11, 6–13 and 6–14 for L4, L5, and S1 nerve
functions.
Localization of Lumbar Disk
Herniation
●
A neurologic physical examination can help determine
the likely location of a herniated lumbar disk.
●
Several classification systems exist for describing where a
disk herniation occurs.
●
Wiltse et al. (1997) proposed an anatomic system familiar
to most surgeons (Figs. 6–15 and 6–16).
Anatomic Features of the
Lumbar Spine
●
Lumbar roots exit the dural sac at an acute angle and
travel inferiorly to exit under the pedicle of the vertebral
body (Fig. 6–17).
●
Depending on the location of the disk herniation,
pressure may be exerted on the exiting or the traversing
nerve root.
●
Only far-lateral or extraforaminal disk herniations
should exert pressure on the exiting nerve root
Figure 6–12: S1 nerve root functions.
L4
nerve root
Sensation
Reflex
Motor
Tibialis anterior muscle
CHAPTER 6 Herniation of the Nucleus Pulposus in the Cervical, Thoracic, and Lumbar Spine 77
S1
L5
nerve root
Sensation
Reflex
None
nerve root
Sensation
Reflex
Motor
Extensor hallucis longus muscle
Figure 6–13: Straight leg raise to test nerve tension.
(e.g., an extraforaminal disk herniation at L4-L5 may
compress the L4 nerve root) (Fig. 6–18).
●
Central, posterolateral, subarticular, or foraminal
lumbar disk herniations will compress the traversing
nerve root (e.g., a foraminal disk herniation at L4L5 will compress the L5 nerve root) (Fig. 6–19,
Box 6–9).
Treatment
Nonsurgical Treatment
●
Initial therapy consists of the following:
●
Bed rest for 1-3 days only
●
Nonsteroidal anti-inflammatory medications
●
Judicious and sparing use of stronger analgesics or
muscle relaxants
●
Progressive return to normal activity; both extremes of
continued bed rest and rapid strenuous physical
activity or physiotherapy have been shown to worsen
symptoms
●
Oral steroids can provide symptomatic relief for leg pain
more than for back pain because of acute inflammation
of a nerve root.
Motor
Peroneus longus and brevis muscle
Figure 6–14: L4 nerve root functions.
●
Steroid use in patients under 50 must be weighed against
the potential for avascular necrosis of the hip and other
side effects.
●
Epidural steroids—Randomized clinical trials and metaanalysis indicate short-term improvement, but long-term
relief is lacking (Watts et al. 1995).
●
Manipulative therapy and physiotherapy have been found
equivalent to medical management (medication or
activity modification) of lumbar disk herniation in terms
of significant short-term pain relief compared with a
placebo, but there has been no proven long-term
benefit.
Surgical Treatment
●
See Table 6–9 and Box 6–10 for surgical treatment.
●
The following are positive predictive factors
(preoperatively) in lumbar disk surgery:
●
No worker’s compensation claim
●
Nonsmoker
●
Absence of back pain
●
Pain extending to the foot (true radicular pain)
●
Positive SLR
●
Larger herniation
●
Good social support system
Pedicular
Infrapedicular
Discal
A
Extraforaminal
Foraminal
Lateral recess
Central
Central canal zone
Subarticular zone
(lateral recess)
Suprapedicle level
Pedicle level
Infrapedicle level
Disk level
Foramnal zone
Extraforaminal zone
B
Figure 6–15: Anatomic “zones” and “levels” identified in the coronal plane.
Central canal zone
Subarticular zone
(lateral recess)
Foramnal zone
(pedicle zone)
L3 pedicle
L3 spinal nerve
L3-4 herniated disk
L4 pedicle
L4 spinal nerve
Extraforaminal zone
(far lateral zone)
Figure 6–16: Anatomic “zones” identified on axial images.
L5 pedicle
L5 spinal nerve
Figure 6–17: Cauda equina and nerve roots with a herniated
disk.
CHAPTER 6 Herniation of the Nucleus Pulposus in the Cervical, Thoracic, and Lumbar Spine 79
Figure 6–18: Axial T2-weighted image of a far-lateral disk
herniation compressing the exiting nerve root.
Figure 6–19: Axial T2-weighted image. A posterolateral disk
herniation causing effacement of the surrounding fat and
partial displacement the traversing nerve root.
Box 6–9:
Natural History of Lumbar Disk
Herniations*
This was a prospective, randomized trial of nonoperative treatment
versus surgical discectomy for isolated lumbar disk herniations. All
patients that “beyond doubt required surgical therapy” and those
with “no indication for operative intervention” were excluded from
the randomized group and results.
●
Nonsurgical
●
25% were cured, 36% improved significantly.
●
Therefore, these 60% would have had unnecessary surgery if
all went to operation.
●
On the flip side, the 40% of patients who needed surgery
would suffer for months if all were required to wait for operative intervention.
●
Three months were sufficient to decide.
●
Surgical
●
Significantly better outcomes occurred at a follow-up of one
year.
●
Insignificantly better outcomes occurred at four years.
●
Only minor changes took place in patients during the last six
years of observation.
* (Weber 1983.)
Table 6–9: Comparison of Techniques for Lumbar
Discectomy
TECHNIQUE PROS CONS
Open discectomy Standard of care More muscle dissection
Better visualization of Longer hospital stay,
nerve increased pain
Potential for iatrogenic
instability
Open microdiscectomy Becoming more standard Limited visualization
Limits muscle damage of nerve
Decreased pain Potential for nerve
Headlamps, loupe injury because of
magnification smaller incision
commonly available size
Microscope-assisted Limited muscle dissection Increased time, cost
discectomy Better lighting, Equipment may not be
magnification available
Potentially shorter
inpatient stays, less
time off work, better
results reported by
some authors
Percutaneous Muscle dissection limited Increased cost
discectomy to portals Steep learning curve
Theoretically less Longer operative time
morbidity, blood loss,
etc.
80 Spine Core Knowledge in Orthopaedics
Box 6–10:
●
A general review of the literature can provide the following indi-
Indications for Operative Disk
Excision
cations for surgical intervention:
●
Major or progressive muscle weakness
●
Symptoms or signs of cauda equina syndrome
●
Radiculopathy and severe pain unrelieved by conservative management and persisting at least 4-6 weeks
●
Evidence exists that pain and radiculopathy that persist more
than six months can develop into chronic nerve pain poorly
treated even with surgical intervention at that point. Some
authors believe, therefore, that a window of opportunity for surgical treatment is present in the face of persistent pain or radicular
findings.
References
Ahn UM, Ahn NU, Buchowski JM et al. (2000) Cauda equina
syndrome secondary to lumbar disk herniation: A meta-analysis of
surgical outcomes. Spine 25: 1515-1522.
Pooled outcomes were analyzed in 322 patients.There was a
significant advantage to treating patients within 48 hours versus
more than 48 hours after the onset of cauda equina syndrome.A
significant improvement in sensory and motor deficits and in
urinary and rectal function occurred in patients who underwent
decompression within 48 hours versus after 48 hours. Older age
and pre–existing bowel or bladder dysfunction were associated
with worse outcomes.
Boden SD, McCowin PR, Davis DO et al. (1990a) Abnormal
magnetic-resonance scans of the cervical spine in asymptomatic
subjects. A prospective investigation. J Bone Joint Surg Am
72:1178-1184.
MRI scans of 63 volunteers with no history of symptoms
indicative of cervical disease and 37 patients with asymptomatic
lesion of the cervical spine were mixed randomly and studied
by 3 independent neurologists. The scans were interpreted as
demonstrating an abnormality in 19% of the asymptomatic
subjects; 14% of those less than 40 years old and 28% of those
older than 40. Of the subjects less than 40, 10% had a HNP and
4% had foraminal stenosis. Of the subjects older than 40, 5%
had a HNP, 3% bulging of the disk, and 20% foraminal stenosis.
The disk was degenerated or narrowed at one level in more
than 25% of the subjects less than 40 and in almost 60% of
those who were older than 40.The prevalence of abnormal
MRI’s of the cervical spine as related in age to asymptomatic
individuals emphasizes the dangers of predicting operative
decisions on diagnostic tests without precisely matching those
findings with clinical signs and symptoms.
Boden SD, Davis DO, Dina TS et al. (1990b) Abnormal magneticresonance scans of the lumbar spine in asymptomatic subjects.
A prospective investigation. J Bone Joint Surg Am 72:403-408.
Bohlman HH, Zdeblick TA. (1988) Anterior excision of herniated
thoracic discs. JBJS 70: 1038-1047.
MRI scans of 63 volunteers with no history of symptoms
indicative of cervical disease and 37 patients with asymptomatic
lesion of the cervical spine were mixed randomly and studied
by 3 independent neurologists. The scans were interpreted as
demonstrating an abnormality in 19% of the asymptomatic
subjects; 14% of those less than 40 years old and 28% of those
older than 40. Of the subjects less than 40, 10% had a HNP and
4% had foraminal stenosis. Of the subjects older than 40, 5%
had a HNP, 3% bulging of the disk, and 20% foraminal stenosis.
The disk was degenerated or narrowed at one level in more
than 25% of the subjects less than 40 and in almost 60% of
those who were older than 40.The prevalence of abnormal
MRI’s of the cervical spine as related in age to asymptomatic
individuals emphasizes the dangers of predicting operative
decisions on diagnostic tests without precisely matching those
findings with clinical signs and symptoms.
The authors treated 22 thoracic disk herniations in 19 patients
with excision using an anterior transthoracic decompression or a
costotransversectomy, and they reported a 48-month follow-up.
Of the patients, 16 had an excellent or a good result, 1 had a fair
result, and 2 had a poor result. Of the 14 patients who had had
motor weakness preoperatively, 12 had varying degrees of
improvement in motor function postoperatively. Pain was
relieved or reduced in 18 patients.The authors conclude that
although the results were good, the procedure is associated
with some risk of damage to the spinal cord. It therefore
requires meticulous preoperative planning and careful surgical
technique.
Borenstein DG,Wiesel SW, Boden SD, eds. (2004) Low Back and
Neck Pain: Comprehensive Diagnosis and Management, 3rd
edition. Philadelphia: Saunders.
Dommisse GF. (1974) The blood supply to the spinal cord:A
critical vascular zone in spinal surgery. JBJS 56B: 225-235.
The author studied cadavers and radiographs of patients to
outline the normal variants of the blood supply to the spinal
cord. Descriptions of three longitudinal vessels, the differential
metabolic demands of grey and white matter, and the radicular
arteries reinforcing the longitudinal arterial channels at various
levels, including the artery of Adamkiewicz, are presented.
Dowd GC,Wirth FP. (1999) Anterior cervical discectomy: Is fusion
necessary? J Neurosurg (Spine 1) 90: 8-12.
A prospective, randomized trial of anterior cervical discectomy
with and without fusion found no difference in patient
satisfaction and return to preoperative activity levels.Though
the fusion rate was higher in the fusion group, this did not
correlate with the outcome.The authors suggest that the
addition of fusion to the procedure may be unnecessary.
Fardon DF, Milette PC. (2001) Nomenclature and classification of
lumbar disk pathology: Recommendations of the combined task
forces of the North American Spine Society, American Society of
Spine Radiology, and American Society of Neuroradiology. Spine
26: E93-E113.
This work represents the collaborative efforts of the three
societies, offering recommendations for standardized
nomenclature involving disk pathology in the lumbar spine.
Kelsey J, Githens PB,Walter SD et al. (1984) An epidemiology
study of acute prolapsed cervical intervertebral discs. J Bone Joint
Surg Am 66(6): 907-914.
The authors conducted an epidemiological study in a patient
population of acute prolapsed cervical disks. It was concluded
CHAPTER 6 Herniation of the Nucleus Pulposus in the Cervical, Thoracic, and Lumbar Spine 81
that individuals in the fifth decade were more likely to
experience cervical disk herniation, and men were more likely
to be affected than women. Factors that may contribute to the
development of the condition were also described.
Narayan P, Haid RW. (2001) Treatment of degenerative cervical disk
disease. Neurol Clin 19: 217-229.
The article explains both the surgical and the nonoperative
approaches to the treatment of various types of cervical disk
disease. Infor mation regarding the radiologic evaluation of each
abnormality is also given.The article focuses on the treatment
of cervical disk disease to relieve any associated radiculopathy or
myelopathy.
Rushton SA, Albert TJ. (1998) Cervical degenerative disease:
Rationale for selecting the appropriate fusion technique (anterior,
posterior, and 360 degrees). Ortho Clin N Am 29: 755-777.
This article reviews the rationale and indications for various
spinal surgery techniques. Success rates for various procedures,
as well as the results and complications associated with each, are
described.
Scherping SC. (2002) Cervical disk disease in the athlete. Clin
Sports Med 21: 37-47.
This article reviews cervical disk disease and presents
information on clinical presentation, imaging and diagnosis, and
management. Although the article concludes with information
regarding the management of cervical disk disease in the athlete,
much of the article is concerned with general cervical spine
abnormalities.
Simpson JM, Silveri CP, Simeone FA et al. (1993) Thoracic disk
herniation: Reevaluation of the posterior approach using a
modified costotransversectomy. Spine 18: 1872-1877.
Using a posterolateral approach (costotransversectomy or
transpedicular), 23 thoracic disk herniations were decompressed
with a follow-up averaging 58 months. An excellent or good
result was achieved in 16 patients; 3 patients had a fair result.
There were no poor results. All 6 patients with significant
preoperative lower extremity weakness improved. Pain was
relieved in 16 patients and reduced in 3.There were no
significant neurologic complications associated with the
procedure.The authors conclude that posterolateral
decompression for thoracic disk herniation remains a viable
alternative without the inherent risk and morbidity of a
transthoracic approach.
Sonntag VKH, Klara P (1996) Is fusion necessary after anterior
cervical discectomy? Spine 21: 1111-1113.
Sonntag and Klara express opposing views on the need for
fusion after discectomy and support their perspectives with
clinical experience and a review of the pathoanatomy of disk
disease. Sonntag believes that most patients are well served with
discectomy alone, avoiding the complications of graft harvest
and potential nonunion. Klara thinks that the interposed graft
restores foraminal height and maintains cervical lordosis, both
of which are important to a good outcome.
Stillerman CB, Chen TC, Couldwell WT et al. (1998) Experience
in the surgical management of 82 symptomatic herniated thoracic
discs and review of the literature. J Neurosurg 88: 623-33.
The authors surgically treated 71 patients with 82 herniated
thoracic disks.The most common sites of disk herniation
requiring surgery were from T8 to T11. Evidence of antecedent
trauma was present in 37% of the patients; 94% were
centrolateral and 6% were lateral. Evidence of calcification was
present in 65% of patients, and in 7% intradural extension was
noted at surgery.The authors found that 10 patients (14%) had
multiple herniations. Four surgical approaches were used for the
removal of these 82 disk herniations: transthoracic in 49 (60%),
transfacet pedicle-sparing in 23 (28%), lateral extracavitary in 8
(10%), and transpedicular in 2 (2%). Postoperative evaluation
revealed improvement or resolution of pain in 47 (87%) of 54,
hyperreflexia and spasticity in 39 (95%) of 41, sensory changes
in 36 (84%) of 43, bowel or bladder dysfunction in 13 (76%) of
17, and motor impairment in 25 (58%) of 43. Complications
occurred in 12 (14.6%) of the 82 disks treated surgically. Major
complications were seen in 3 patients and included
perioperative death from cardiopulmonary compromise,
instability requiring further surgery, and an increase in the
severity of a preoperative paraparesis.
Takhtani D, Melhem ER. (2002) MR imaging in cervical spine
trauma. Clin Sports Med 21: 49-75.
A review of the continuous improvements in MRI as it applies
to spine surgery.The specific types of MRI sequence
appropriate for various spinal conditions are described.
Vanichkachorn JS,Vaccaro AR. (2000) Thoracic disk disease:
Diagnosis and treatment. JAAOS 8: 59-169.
This is a review of the anatomy, epidemiology, clinical
presentation, imaging, natural history, and treatment of thoracic
disk disease.The authors emphasize the natural tendency of
these patients to improve with nonsurgical care, give indications
for operative intervention, and explain the relative merits of the
various surgical approaches in terms of outcome and
complications.
Watts RW, Silagy CA. (1995) A meta-analysis on the efficacy of
epidural corticosteroids in the treatment of sciatica.Anesth
Intensive Care 23: 564-569.
This meta-analysis included 907 pooled patients. Significant
pain relief (75% on average) occurred in patients treated with
epidural steroid injections for the treatment of sciatica. Shortterm results were significantly different than controls.
Weber H. (1983) Lumbar disk herniation: A controlled, prospective
study with ten years of observation. Spine 8: 131-140.
In this study, 126 patients with uncertain indications for surgical
treatment had treatment chosen by randomization in surgical or
nonsurgical management. Statistically better outcomes were
reported in the surgical group at one year, less difference was
seen at four years, and no real changes in the last six years were
observed.A high crossover rate, imprecise definitions of
nonsurgical care, and author-evaluated outcomes are criticisms
of this article.The author concludes that it is safe to wait on
uncomplicated lumbar disk herniations because many patients
get better without surgery.
Williams KD, Park AL. (2003) Lower back pain and disorders of
intervertebral disks. In: Campbell’s Operative Orthopaedics (Canale
ST, ed.), 10th edition. Philadelphia: Mosby.
Wiltse LL, Berger PE, McCulloch JA. (1997) A system for
reporting the size and location of lesions of the spine. Spine 22:
1534-1537.
82 Spine Core Knowledge in Orthopaedics
Anatomic zones and levels are defined, using a system intuitive
to most surgeons, and recommendations are made for reporting
pathology in the spine, particularly in relation to lumbar disk
herniations.
Wood KB, Garvey TA, Gundry C et al. (1995) Magnetic resonance
imaging of the thoracic spine: Evaluation of asymptomatic
individuals. JBJS 77: 1631-1638.
Two studies examine a group of 90 asymptomatic patients with
MRI scans of their thoracic spines.The authors describe the
incidence and epidemiology of thoracic disk herniations and
follow a subgroup of these patients for an average of 26 months.
Wood KB, Blair JM, Aepple DM et al. (1997) The natural history of
asymptomatic thoracic disk herniations. Spine 22: 525-529.
This study examines a group of 90 asymptomatic patients with
MRI scans of their thoracic spines. Based on the results of this
study, the authors believe that asymptomatic disk herniations
may exist in a state of relative flux yet exhibit little change in
size and remain asymptomatic.There was a trend, however, for
small disk herniations either to remain unchanged or to increase
in size and for large disk herniations often to decrease in size.
CHAPTER
7
Cervical, Thoracic, and Lumbar
Degenerative Disk Disease
Spinal Stenosis
Brady T. Vibert* and Jeffrey S. Fischgrund §
* M.D., Resident, Orthopaedic Surgery, William Beaumont Hospital, Royal Oak, MI
§ M.D., Spine Surgeon,William Beaumont Hospital, Royal Oak, MI
Introduction
●
Degenerative disk disease is manifested as loss of fluid,
height, and integrity of the intervertebral disk. It may
result in osteophyte formation, ligament hypertrophy,
and synovial cyst formation.
●
Spinal stenosis, the narrowing of the spinal canal or
neural foramina, may occur because of degenerative
disk disease and resulting hypertrophic changes.
Spinal stenosis may result in radiculopathy,
myelopathy, or both in the cervical and thoracic spine.
Spinal stenosis in the lumbar spine may result in
radiculopathy, neurogenic claudication, or cauda
equina syndrome—that is, saddle anesthesia
(perineal) and loss of bowel and bladder function in
severe cases.
●
Radiculopathy is a nerve root dysfunction that results in
a lower motor nerve lesion only in the affected nerve’s
distribution.
●
Myelopathy is a condition affecting the spinal cord and
resulting in upper motor neuron dysfunction.
●
Spinal stenosis in the cervical and thoracic spine may
result in myelopathy
●
Thoracic spinal stenosis caused by degenerative changes is
rare because the rib cage, which provides rigid structural
support, minimizes motion at the thoracic intervertebral
motion segments.
Pathophysiology
●
Spinal stenosis can come from advanced degenerative
disk disease.
●
All disks age, but pathologic disk degeneration is an
accelerated and exaggerated course of normal aging
(Fig. 7–1).
Classification
Arnoldi Classification of Spinal Canal
Stenosis
I. Congenital or developmental
a. Idiopathic
b. Achondroplastic
c. Osteopetrosis
II. Acquired
a. Degenerative
i. Central
ii. Lateral recess and foraminal
b. Iatrogenic
i. Postlaminectomy
ii. Postfusion
iii. Postdiscectomy
c. Miscellaneous disorders
i. Acromegaly
ii. Paget’s
83
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