Download Chapter 106 - Spinal Cord Disorders

CHAPTER 106 Spinal Cord Disorders
Andrew D. Perron and J. Stephen Huff
PERSPECTIVE
Spinal cord disorders encompass a wide range of pathologic entities and affect all age groups. Some spinal cord disorders may have
catastrophic outcomes if they are not recognized early in the clinical course. The ultimate neurologic outcome with many of these
disorders may depend on expeditious recognition in the emergency department (ED), with appropriate initial investigations,
neuroimaging, management, and consultation for definitive
therapy. Early presentations of spinal cord syndromes are frequently subtle, and diagnosis may be difficult if not impossible in
the early stages of disease. As with many disease processes affecting
the nervous system, correct diagnosis and appropriate management require knowledge of the anatomic organization of the
spinal cord and skill in taking the history and in performing the
neurologic examination.
This chapter generally is concerned with nontraumatic processes affecting the spinal cord and its vascular supply as well as
processes compressing the spinal cord. Spinal cord trauma is discussed in Chapter 43.
PRINCIPLES OF DISEASE
Anatomy
In adults, the spinal cord is approximately 40 cm long and extends
from the foramen magnum, where it is continuous with the
medulla oblongata, to the body of the first or second lumbar
vertebra. Like the brain, the spinal cord is covered by three meningeal layers: the inner pial layer, the arachnoid, and the outer
dural layer. At its lower end, the spinal cord tapers into the conus
medullaris, where several segmental levels are represented in a
small area. The lumbar and sacral nerve roots form the cauda
equina as they descend caudally in the thecal sac before exiting the
spinal canal at the respective foramina. The non-neural filum
terminale runs from the tip of the conus and inserts into the dura
at the level of the second sacral vertebra.
Two symmetrical enlargements of the spinal cord contain the
segments that innervate the limbs. The cervical enlargement (cord
level C5 to T1) gives rise to the brachial plexus and subsequently
to the peripheral nerves of the upper extremity. The lumbar
enlargement (L2 to S3) gives rise to the lumbosacral plexus and
peripheral nerves of the lower extremity. The space surrounding
the spinal cord within the spinal canal is reduced in the area of
the enlargements, potentially leaving the cord more vulnerable to
compression in these regions. At each segmental level, anterior
(ventral) and posterior (dorsal) roots arise from rootlets along the
anterolateral and posterolateral surfaces of the cord. At each level,
the anterior root conveys the outflow of the motor neurons in the
anterior horn of the spinal cord, and the posterior root contains
sensory neurons and fibers that convey sensory inflow.
The arterial supply of the spinal cord is derived primarily from
two sources. The single anterior spinal artery arises from the
paired vertebral arteries. This anterior spinal artery runs the entire
length of the cord in the midline anterior median sulcus and supplies roughly the anterior two thirds of the spinal cord. Blood
supply to the posterior third of the spinal cord is derived from the
smaller paired posterior spinal arteries. The anterior and the posterior spinal arteries receive segmental contributions from radicular arteries, the largest being the radicular artery of Adamkiewicz,
which typically originates from the aorta between T8 and L4. The
venous drainage of the cord largely parallels the arterial supply.
The internal anatomy of the spinal cord is divided into central
gray matter, which contains cell bodies and their processes, and
surrounding white matter, where the ascending and descending
myelinated fiber tracts are located. These fiber tracts are organized
into discrete bundles; the ascending tracts convey sensory information, and the descending tracts convey the efferent motor
impulses and visceral innervation.
For clinical purposes, neuroanatomy of the spinal cord may be
greatly simplified, as depicted in Figure 106-1. Major ascending
sensory tracts are represented on the right side of the figure, with
motor tracts on the left side. The posterior columns carry afferent
ascending proprioceptive and vibratory information on the ipsilateral side of the cord to the area stimulated; decussation of these
fibers occurs in the medulla so that contralateral cortical representation is consistent. The lateral spinothalamic tract conveys
afferent information about pain and temperature in a portion of
the lateral column of white matter. (Tracts are named with the
point of origin first; the spinothalamic tract, for example, arises
in the spinal cord and travels to the thalamus.) The tract is laminated so that sacral fibers are represented most laterally. Crossing
of fibers from this tract occurs near the level of entry of the spinal
nerve; a cord lesion affecting only one lateral spinothalamic tract
results in decreased or absent pain and temperature perception
below the level of injury on the contralateral side of the body.
For clinical purposes, the major descending motor tract is represented in the lateral corticospinal tract (which, as the name
implies, originates in the cortex and descends to the spinal cord).
This tract also is anatomically organized, with efferent motor
axons to the cervical area located medially and the sacral efferent
axons located laterally. Decussation of this descending tract occurs
in the medulla. The cell bodies of the lower motor neurons (anterior horn cells) are in the ventral (anterior) portion of the gray
matter of the spinal cord.
1419
1420 PART III ◆ Medicine and Surgery / Section Seven • Neurology
Lateral corticospinal tract
Descending tract
Voluntary movement
Posterior columns
Ascending proprioceptive
and vibratory senses
the glans penis or a tug on the Foley catheter. The termination of
the spinal shock phase of injury is heralded by the return of the
bulbocavernosus reflex; increased muscle tone and hyperreflexia
follow later.1,5,6
Incomplete Spinal Cord Lesions
Incomplete spinal lesions are characterized by preservation of
function of various portions of the spinal cord. Of all incomplete
spinal lesions, most can be classified generally as one of three
clinical syndromes: central cord syndrome, Brown-Séquard syndrome, or anterior cord syndrome (Table 106-1).
Central Cord Syndrome
Lateral spinothalamic tract
Ascending pain and
temperature information
Figure 106-1. Simplified spinal cord anatomy showing clinically
essential motor and sensory tracts. (Photomicrograph courtesy John
Sundsten, Digital Anatomist Project, University of Washington.)
CLASSIFICATION OF SPINAL
CORD SYNDROMES
The anatomic organization of the spinal cord lends itself to a corresponding anatomic-pathophysiologic classification of cord dysfunction. Any of the different anatomic syndromes may be the
final clinical picture of a variety of clinical processes. The syndromes frequently exist in partial or incomplete forms, adding to
the diagnostic difficulty.
Complete (Transverse) Spinal
Cord Syndrome
Complete spinal cord lesions may be manifested as either acute or
subacute pathologic processes. A complete spinal cord lesion is
defined as a total loss of sensory, autonomic, and voluntary motor
innervation distal to the spinal cord level of injury. Reflex responses
mediated at the spinal level, such as muscle stretch (deep tendon)
reflexes, may persist, although they also may be absent or abnormal. Autonomic dysfunction may be manifested acutely with
hypotension (neurogenic shock) or priapism. The most common
cause of the complete transverse cord syndrome is trauma,
although this anatomic syndrome is nonspecific as to etiology.1,2
Other causes of acute complete cord syndrome include infarction,
hemorrhage, and entities causing extrinsic compression. In
patients with acute complete transverse syndromes that persist for
more than 24 hours, functional recovery does not occur in 99%.3,4
Any evidence of preserved cord function below the level of injury
denotes a partial rather than a complete lesion. Signs such as
persistent perineal sensation (sacral sparing), reflex rectal sphincter tone or voluntary rectal sphincter contraction, and even slight
voluntary toe movement suggest a partial cord lesion, which
usually carries a better prognosis than a complete lesion.1
Spinal shock refers to the loss of muscle tone and reflexes with
complete cord syndrome during the acute phase of injury. The
intensity of the spinal shock increases with affected spinal cord
level.5 Spinal shock typically lasts less than 24 hours but has been
reported occasionally to last days to weeks.5,6 A marker of spinal
shock is loss of the bulbocavernosus reflex, which is a normal
cord-mediated reflex that may be preserved in complete cord
lesions. The bulbocavernosus reflex involves involuntary reflex
contraction of the anal sphincter in response to a squeeze of
Central cord syndrome, first described by Schneider and colleagues in 1954, is the most prevalent of the partial cord syndromes.7,8 Because of the anatomic organization of the spinal cord,
a central cord injury is characterized by bilateral motor paresis;
upper extremities are affected to a greater degree than lower
extremities, and distal muscle groups are affected to a greater
degree than proximal muscle groups. Sensory impairment and
bladder dysfunction are variable features. At times, burning dysesthesias in the upper extremities may be the dominant feature.9
Central cord injury affects the central gray matter and the central
portions of the corticospinal and spinothalamic tracts. It is caused
most often by a hyperextension injury; the postulated mechanism
is squeezing or pinching of the spinal cord anteriorly and posteriorly by inward bulging of the ligamentum flavum. The most
common cause of such injuries is a fall, followed in frequency by
a motor vehicle crash.7,8 The result is contusion to the spinal cord,
with the central portion being most affected. This injury often
occurs in elders with degenerative arthritis and spinal stenosis in
the cervical area but may affect any patient with cervical canal
narrowing of any etiology (e.g., congenital narrow canal as seen
in achondroplasia or canal narrowing from disk protrusion or
tumor). The prognosis with central cord syndrome depends on
the degree of injury at presentation and the patient’s age.10,11 In
patients younger than 50 years, more than 80% regain bladder
continence, and approximately 90% return to ambulatory status.
In patients older than 50 years, only 30% regain bladder function,
and approximately 50% regain the ability to ambulate.11
Brown-Séquard Syndrome
Brown-Séquard syndrome, first described in 1846 by the one physician for whom it is named,12 is the result of an anatomic or
functional hemisection of the spinal cord. Usually associated with
penetrating injuries,13 Brown-Séquard syndrome also may be seen
with compressive or intrinsic lesions. The syndrome has been
reported in association with spinal cord tumors, spinal epidural
hematoma, vascular malformations, cervical spondylosis, degenerative disk disease, herpes zoster myelitis, and radiation injury
and as a complication of spinal instrumentation.13,14 The syndrome in its pure form is characterized by ipsilateral loss of motor
function and proprioception or vibration, with contralateral loss
of pain and temperature sensation below the spinal cord level of
injury. Because fibers associated with the lateral spinothalamic
tract ascend or descend one or two spinal cord segments before
crossing to the contralateral side, ipsilateral anesthesia (pain and
temperature modalities) may be noted one or two segments above
the lesion, although this observation is variable. Most patients
with Brown-Séquard syndrome incur only partial sensory and
motor impairment, and the classic pattern is not seen.11,13,15
Brown-Séquard syndrome carries the best prognosis of any of the
incomplete spinal cord syndromes. Fully 80 to 90% of patients
with Brown-Séquard syndrome regain bowel and bladder func-
Chapter 106 / Spinal Cord Disorders 1421
Table 106-1 Spinal Cord Syndromes
SYNDROME
SENSORY
MOTOR
SPHINCTER INVOLVEMENT
Variable
Upper extremity weakness, distal
> proximal
Variable
Ipsilateral position and vibration sense loss
Contralateral pain and temperature
sensation loss
Motor loss ipsilateral to cord
lesion
Variable
Loss of pin and touch sensation
Vibration, position sense preserved
Motor loss or weakness below
cord level
Variable
Loss of sensation below level of cord injury
Loss of voluntary motor function
below cord level
Sphincter control lost
Conus medullaris syndrome
Saddle anesthesia may be present, or
sensory loss may range from patchy to
complete transverse pattern
Weakness may be of upper motor
neuron type
Sphincter control impaired
Cauda equina syndrome
Saddle anesthesia may be present, or
sensory loss may range from patchy to
complete transverse pattern
Weakness may be of lower motor
neuron type
Sphincter control impaired
Central cord syndrome
Brown-Séquard syndrome
Anterior cord syndrome
Transverse cord syndrome—complete
tion, 75% regain ambulatory status, and 70% become independent in their activities of daily living.11
Anterior Cord Syndrome
Anterior cord syndrome is characterized by loss of motor function, pinprick, and light touch below the level of the lesion with
preservation of posterior column modalities, including some
touch, position, or vibratory sensation. Although most reported
cases of anterior spinal syndrome follow aortic surgery,16 the syndrome also may occur after severe hypotension, infection, myocardial infarction, vasospasm from drug reaction, and aortic
angiography.17 The anatomic lesion may be caused by a cervical
hyperflexion injury resulting in a cord contusion or by protrusion
of bone fragments or herniated cervical disk material into the
spinal canal. Rarely, it is produced by laceration or thrombosis of
the anterior spinal artery or a major radicular feeding vessel.11
Patients present with characteristic mixed motor and sensory neurologic findings as noted before. Functional recovery varies; most
improvement occurs during the first 24 hours, but little improvement is expected thereafter.4 Although anterior cord lesions from
ischemia usually are incomplete, patients without motor function
at 30 days have little or no likelihood of regaining any motor function by 1 year.16,18 Overall, only 10 to 20% of patients with this
entity regain some muscle function, and even in this group, there
is little power or coordination.11
Conus Medullaris and Cauda
Equina Syndromes
The separation of conus medullaris and cauda equina lesions in
clinical practice is difficult because the clinical features of the
1422 PART III ◆ Medicine and Surgery / Section Seven • Neurology
disorders overlap. In addition, a combined lesion may occur that
masks clear clinical symptoms or signs of either an upper or a
lower motor neuron type of injury. The conus medullaris is the
terminal end of the spinal cord, located at approximately the L1
level in adults. The conus medullaris syndrome may involve disturbances of urination (usually from a denervated, autonomic
bladder that is manifested clinically with overflow incontinence)
and sphincter impairment or sexual dysfunction. Sensory involvement may affect the sacral and coccygeal segments, resulting in
saddle anesthesia. Pure lesions of the conus medullaris are rare.19
Upper motor neuron signs, such as increased motor tone and
abnormal reflexes, may be present, but their absence does not
exclude the syndrome. The conus medullaris syndrome can be
caused by central disk herniation, neoplasm, trauma, or vascular
insufficiency. Because the conus is such a small structure, with
lumbar and sacral segments represented in a small area, a lesion
usually causes bilateral symptoms. This finding may help distinguish lesions of the conus from lesions of the cauda equina, which
often are unilateral.19
The cauda equina (Latin for “horse’s tail”) is the name given to
the lumbar and sacral nerve roots that continue on within the
dural sac caudal to the conus medullaris. Not a true “cord syndrome,” cauda equina syndrome represents dysfunction at the
level of nerve roots, but the anatomic clustering of nerve roots
within the lumbar dural sac allows injury to several nerve roots to
occur simultaneously. The etiologic lesion in the cauda equina
syndrome usually is a midline rupture of an intervertebral disk,
most commonly at the L4-5 level. Tumors and other compressive
masses also may cause the syndrome. As in the conus medullaris
syndrome, patients generally present with progressive symptoms
of fecal or urinary incontinence, impotence, distal motor weakness, and sensory loss in a saddle distribution. Muscle stretch
reflexes also may be reduced. Urinary retention is the most consistent finding, with a sensitivity of 90%.20 Low back pain may or
may not be present.
CLINICAL FEATURES
History
Weakness, sensory abnormalities, and autonomic dysfunction are
the cardinal manifestations of spinal cord dysfunction. The tempo
and degree of impairment often reflect the disease process. Past
medical history is vital because a history of coagulopathy or other
systemic processes may be elicited. A history of cancer should
suggest the possibility of metastatic disease. Recent trauma raises
the possibility of vertebral fracture or disk protrusion.
Physical Examination
The physical examination pertinent to spinal cord dysfunction
involves testing in three areas: (1) motor function, (2) sensory
function, and (3) reflexes. Each component is best tested with the
anatomic organization of the spinal cord in mind to help determine the level of the spinal cord dysfunction.
Motor Function
Testing of motor function encompasses examination of muscle
bulk, tone, and strength. Muscle bulk is easily examined in large
motor groups, such as the thigh or calf muscles, the biceps, and
the triceps. Inspection of the intrinsic hand muscles also may be
helpful for determination of muscle bulk; wasting may be evident
as hollowed or recessed regions of the hand. Decreased mass,
asymmetry, or fasciculations should be noted. Tone is tested with
repeated passive knee, elbow, or wrist flexion, with the examiner
feeling for abnormally increased or decreased resistance. Rapid
pronation-supination of the forearm is another useful method to
assess tone. Increased tone may indicate spasticity or an upper
motor neuron lesion, whereas decreased tone corresponds with
lower motor neuron, motor endplate, or muscle problems. Finally,
motor strength is graded in the upper and the lower extremities.
Motor grading for the neurologic examination is relatively
straightforward. Note that a tremendous gradient of strength is
within the fourth grade of the scale. Scored on a scale of 0 to 5,
neuromuscular functioning is graded as follows:
0. No firing of the muscle is present.
1. The muscle fires but is unable to move the intended part.
2. The muscle is able to move the intended part with gravity
eliminated.
3. The muscle is able to move the intended part against gravity.
4. The muscle is able to move the intended part, but not at full
strength.
5. Full muscle strength is present.
A rectal examination is performed to assess voluntary sphincter
contraction, resting tone, and, as described previously, the bulbocavernosus reflex. Although it is not commonly thought of as a
physical examination maneuver, a post-void residual urine volume
may be important for assessment of bladder function. A post-void
residual volume of more than 100 to 200 mL in a patient without
prior voiding difficulty might suggest bladder dysfunction of neurologic cause.
Sensory Function
Sensory testing requires a cooperative patient and an attentive
examiner. The spinal cord–related modalities that may be clinically useful include testing for pinprick and light touch (contralateral lateral spinothalamic tract) and proprioception (ipsilateral
posterior column). Assessment of the patient’s response to pinprick, light touch, and proprioception in all four extremities is
necessary if a neurologic injury is suspected. Testing of sacral
dermatomes is an important part of the examination in some
patients. As previously noted, sacral sparing is an important
finding indicating that spinal cord dysfunction may be incomplete. The sensory fibers from sacral dermatomes are more peripherally located in the ascending fiber bundles; central or partial cord
lesions may ablate sensation in the extremities yet allow some
perception of sensation in the sacral area.
Reflexes
Muscle stretch (deep tendon) reflexes may be tested rapidly at the
bedside. Responses are graded on a scale of 0 to 4+, with 2 being
normal. Hyperactive reflexes suggest upper motor neuron disease
(affecting the neurons or their outflow from the brain or spinal
cord), as do sustained clonus and Babinski’s sign. The absence of
these reflex changes does not constitute evidence that a myelopathy is not present. In fact, one small series noted a low incidence
of extensor plantar responses as well as a lack of hyperreflexia in
patients presenting to the ED with acute or progressive cord compression or myelopathies.21 Reflexes also may be diminished or
absent when sensation is lost or when spinal shock is present.
Diseases of muscles or neuromuscular junctions also may decrease
reflexes. In acute cord injury, reflexes may be diminished in the
acute phase. The bulbocavernosus reflex may be helpful in this
assessment.
DIAGNOSTIC STRATEGIES
Historical or physical examination findings that suggest spinal
cord dysfunction prompt further investigations. The basic strategy
is to detect or to exclude extrinsic compressive lesions or other
potentially treatable entities. Magnetic resonance imaging (MRI)
Chapter 106 / Spinal Cord Disorders 1423
Table 106-2 Clinical Characteristics of Neuromuscular Diseases
HISTORY
STRENGTH
DTR
SENSATION
WASTING
Myelopathy
Trauma, infection, cancer
Normal to decreased
Increased
Normal to decreased
No
(yes if chronic)
Motor neuron disease (ALS)
Progressive difficulty with
swallowing, speaking, walking
Decreased
Increased
Normal
Yes
Neuropathy
Recent infection
Ascending weakness
Normal or decreased
Distal > proximal
Decreased
Decreased
Yes
Neuromuscular junction
disease
Food (canned goods)
Tick exposure
Easy fatigability
Normal to fatigue
Normal
Normal
No
Myopathy
Thyroid disease
Previous similar episodes
Decreased
Proximal > distal
Normal
Normal
Yes
ALS, amyotrophic lateral sclerosis; DTR, deep tendon reflex.
has changed the diagnostic approach to patients with suspected
spinal cord dysfunction. Plain radiographs and computed tomography (CT) scans may show bone and some soft tissue abnormalities. Conventional radiographs and CT scans are required in
patients with trauma or suspected bone involvement by tumor or
degenerative processes, but MRI shows many of these abnormalities and defines the spinal cord as well as the soft tissue structures
associated with it. Tissue damage patterns within the cord, such
as hemorrhage and edema, also may be detected with MRI. CT
myelography may be able to answer some of these questions in
patients in whom implanted metal precludes MRI but generally
does not yield the same level of detail. After imaging studies
exclude compressive lesions or other masses affecting the spinal
cord, the possibility of inflammatory or demyelinating disorders
remains. Lumbar puncture may be useful in diagnosis by revealing
an inflammatory cerebrospinal fluid (CSF) formula.
DIFFERENTIAL CONSIDERATIONS
The prime principle in management of spinal cord dysfunction is
to consider and exclude potentially treatable clinical conditions.
The clinical assessment of spinal cord dysfunction is limited to
detection of weakness, sensory alterations, sphincter dysfunction,
and perhaps reflex abnormalities. There may be pain in the back,
depending on the pathologic process, but generally it is not helpful
in formulating a list of considerations for the differential diagnosis. Because potential functional loss and impact on quality of life
are great, the detection of a process for which some intervention
is possible assumes great importance. A likely diagnosis of spinal
cord infarction may be entertained, but the pursuit of a treatable
process, such as spinal cord compression from an epidural hematoma, should be seriously considered.22 This discovery process
may involve specialty consultation or studies that may not be
readily available in all settings, such as MRI. As a general rule,
liberal use of consultation and imaging is recommended when the
possibility of spinal cord dysfunction is considered. The history
may suggest a specific cause and will guide the tempo of investigation. The caveat is that spinal cord diseases may mimic many other
disease processes, and neither the history nor physical examination may allow diagnosis until appreciable neurologic dysfunction
has developed.
The picture of a complete transverse spinal cord syndrome with
paraplegia, sensory loss at a clear anatomic level, and sphincter
dysfunction cannot be fully simulated by other anatomic lesions.
Incomplete or evolving spinal cord syndromes may be imitated by
other disease processes. It is always prudent to focus the differential diagnosis on anatomic considerations—the classic “where is
Nontraumatic Causes of Spinal
BOX 106-1 Cord Dysfunction
Processes Affecting the Spinal Cord or Blood
Supply Directly
Multiple sclerosis
Transverse myelitis
Spinal arteriovenous malformation, subarachnoid hemorrhage
Syringomyelia
HIV myelopathy
Other myelopathies
Spinal cord infarction
Compressive Lesions Affecting the Spinal Cord
Spinal epidural hematoma
Spinal epidural abscess
Diskitis
Neoplasm
Metastatic
Primary CNS
HIV, human immunodeficiency virus; CNS, central nervous system.
the lesion?” approach (Table 106-2). Progressive lower extremity
weakness and sensory alteration may represent cord dysfunction
but could reflect an intracranial vertex mass with bilateral cortical
dysfunction. Ataxia may be a finding in cerebellar disease but also
has rarely been reported as an isolated finding with spinal cord
compression. Another example is rapidly progressive paralysis in
a patient with areflexia and quadriplegia; ascending paralysis
(Landry-Guillain-Barré syndrome) at times may mimic an acute
cord lesion.
In general, pathologic processes involving the spinal cord may
be divided into processes affecting the cord or its blood supply
primarily, such as demyelination, infection, or infarction, and processes that compress the cord, most often originating outside the
dura (Box 106-1). Myelitis is a comprehensive term for spinal cord
inflammation with dysfunction, and the potential causes are
legion. The clinical presentation is often similar across the variety
of entities that may cause cord compression. The tempo of the
process may yield a different clinical picture. In chronic compression, muscle wasting and abnormal reflexes may be present,
whereas both of these may be lacking in acute compression. A
neurologic deficit in concert with back pain strongly suggests a
spinal cord lesion causing compression of neural elements, necessitating prompt investigation to identify a specific cause. Atypical
presentations for these lesions are the rule, and additional diagnostic studies should be pursued as appropriate.
1424 PART III ◆ Medicine and Surgery / Section Seven • Neurology
MANAGEMENT
Just as the clinical manifestations of spinal cord dysfunction are
nonspecific with respect to etiology, the treatment of many of the
disease entities often is nonspecific. Steroid administration had
been traditionally recommended as therapy in spinal cord trauma,
although currently this use of steroids has been seriously questioned in the medical literature.23-26 Steroids have also been used
with many nontraumatic causes of cord compression, despite the
lack of rigorous clinical studies supporting this use. Radiation
treatment is recommended for cord compression by tumor.
Surgical consultation for decompression may be considered,
although the indications for surgery and timing of surgery are
controversial.
A specific diagnosis is needed to guide therapy. Accordingly,
involvement of appropriate consultants and discussion of what
may be understudied therapies are suggested.
SPECIFIC DISEASE PROCESSES
As noted earlier, spinal cord disorders may be grouped into
lesions resulting from processes intrinsic to the cord or vasculature
and lesions causing extrinsic compression. The order of the following discussion roughly corresponds with the organization of
Box 106-1.
Intrinsic Cord Lesions
Multiple Sclerosis
Principles of Disease. Demyelination denotes a disease process with
the prominent feature of partial or complete loss of the myelin
surrounding the axons of the central nervous system. Multiple
sclerosis (MS) is the most common example of such a process;
spinal cord involvement may dominate the clinical picture.27
Clinical Features. Central nervous system lesions that are “scattered in time and space” are the hallmark of MS, as described in
more detail in Chapter 105. The demyelinated segments do not
transmit action potentials normally, resulting in a wide variety of
spinal cord–related abnormalities, depending on the location and
extent of the demyelination. In addition to patchy motor and
sensory deficits, patients with MS may complain of bladder dysfunction or tremor or demonstrate evidence of a transverse partial
or complete cord syndrome mimicking a compressive spinal
lesion.27, 28 Spinal cord lesions in MS primarily involve the lateral
corticospinal tracts, the posterior columns, and the lateral spinothalamic tracts. Motor system dysfunction is the most frequent
manifestation of MS involvement of the spinal cord, usually as a
result of lesions in the lateral corticospinal tracts.
The examination of patients with MS often reveals paresis,
increased muscle tone, hyperreflexia, clonus, and Babinski’s
response. Spinal cord involvement also may result in
dysautonomias.
Diagnostic Strategies. Spinal MRI is the diagnostic imaging
modality of choice because it can exclude cord compression and
show lesions suggestive of MS.28-30 CSF testing for myelin basic
protein and oligoclonal bands also is a diagnostic option, but no
CSF abnormalities are entirely specific for MS.31,32 Oligoclonal
bands in the CSF may aid in the diagnosis, but they are significant
only if they are not present in the serum as well.31
Differential Considerations. Considerations in the differential
diagnosis include systemic lupus erythematosus, Lyme disease,
neurosyphilis, human immunodeficiency virus (HIV) myelopathy, and other disorders.
Management. MS exacerbations may be treated with high-dose
methylprednisolone, followed by a tapering dose of prednisone.28
Consultation and referral to a neurologist usually are indicated.
Immunosuppressive therapy in patients with the chronic progressive form of the disease has met with variable success.27,28 Because
numerous disorders can mimic MS, the definitive diagnosis of this
disease is usually not made in the ED.33
Transverse Myelitis
Principles of Disease. Acute transverse myelitis refers to acute or
subacute spinal cord dysfunction characterized by paraplegia,
a transverse level of sensory impairment, and sphincter disturbance. It describes a heterogeneous group of inflammatory disease
processes that can affect the spinal cord by interruption of the
ascending or descending pathways in the spinal cord.34 It is relatively rare, with a reported annual incidence of 1 case per 1.3
million population. The presentation may be mimicked by compressive lesions, trauma, infection, or malignant infiltration. The
exact pathogenesis is unknown, although it is noted to follow viral
infection in approximately 30% of patients and commonly is
termed postinfectious myelitis.34,35 Other postulated etiologic categories include infectious, autoimmune, and idiopathic.35-37 No
apparent cause of acute transverse myelitis is identified in 30% of
the patients.35 Progression of symptoms usually is rapid, with 66%
of the cases reaching maximal deficit by 24 hours.38 Symptoms
may progress, however, during days to weeks. The thoracic cord
region is affected in 60 to 70% of cases38; the cervical spinal cord
is rarely affected.39
Clinical Features. In addition to motor, sensory, and urinary
disturbances, patients with acute transverse myelitis may complain of back pain and may have low-grade fever, raising concern
for spinal epidural abscess. As with MS, the examination may
reveal weakness progressing to paresis, hypertonia, hyperreflexia,
clonus, and Babinski’s response. Spinal cord involvement also can
result in dysautonomias.
Diagnostic Strategies. Evaluation for acute transverse myelitis is
done primarily with emergent MRI to exclude compressive lesions.
Results of CSF studies are normal in 40% of the cases, with only
mildly elevated protein level or pleocytosis in the remaining
60%.40 The most essential aspect of the evaluation is to eliminate
a potentially treatable cause, such as spinal epidural abscess, neoplasm, or hematoma.
Differential Considerations. Considerations in the differential
diagnosis for transverse myelitis include MS, spinal epidural
abscess, spinal neoplasm, and hematoma.
Management. Treatment with steroids is of unknown benefit.
Anecdotal reports of improvement after steroid administration
exist,38,41 but some studies have found no benefit to their use.37
Neurologic consultation is suggested, and hospitalization usually
is required.
The clinical course of acute transverse myelitis varies widely,
ranging from complete recovery to death from progressive neurologic compromise.37 Maximal improvement usually is obtained
within 3 to 6 months.42,43 At 5-year follow-up evaluation of one
series of patients with this disease, 30% had a good recovery, 25%
had a fair recovery, 30% had a poor outcome, and 15% had died
as a result of complications of the disease.43
Spinal Subarachnoid Hemorrhage
Principles of Disease. Intraspinal hemorrhage is rare and may
occur in the same anatomic locations as intracranial hemorrhages;
epidural, subdural, subarachnoid, and intramedullary hemorrhages are all possible.5 Spinal subarachnoid hemorrhage usually
is caused by an arteriovenous malformation.44 Hemorrhage from
tumors or cavernous angiomas and spontaneous hemorrhage secondary to anticoagulation therapy also have been reported.45,46
Bleeding may occur exclusively in the subarachnoid space or
within the substance of the spinal cord itself.
Chapter 106 / Spinal Cord Disorders 1425
Clinical Features. Patients present with excruciating back pain,
of paroxysmal onset, at the level of the hemorrhage. This pain also
may be in a radicular distribution or extend into the flank. Patients
may complain of headache and exhibit cervical rigidity if the
blood migrates into the intracranial subarachnoid space, simulating an intracranial subarachnoid hemorrhage. Variable neurologic
deficits depend on the magnitude and anatomic location of the
hemorrhage. These deficits typically include extremity numbness,
weakness, and sphincter dysfunction.45,47 Nuchal rigidity or signs
of meningeal irritation may also be present.
Diagnostic Strategies. The diagnostic study of choice is MRI.
Lumbar puncture also can confirm the presence of blood in
the CSF.
Differential Considerations. Considerations in the differential
diagnosis include epidural abscess, tumor, transverse myelitis,
ischemia from aortic dissection, and anterior spinal artery
thrombosis.
Management. Treatment depends on the etiology of the
hemorrhage. Neurosurgical referral is obtained for further evaluation and for clot evacuation if compression is present. Angiography may be recommended if arteriovenous malformation is
suspected.
Idiopathic Spastic Paraparesis
Syringomyelia
Spinal Cord Infarction
Principles of Disease. Syringomyelia is the presence of a cavitary
lesion within the substance of the spinal cord. A syrinx usually is
a chronic progressive lesion, and its location within the cord determines the constellation of neurologic findings on examination.
Clinical Features. Headache and neck pain are the most common
complaints, followed by sensory disturbance, gait disorder, and
lower cranial nerve dysfunction.48 The classic pattern of sensory
deficit involves a loss of pain and temperature sensation in the
upper extremities with preservation of proprioception and light
touch. This phenomenon is described as a “dissociative anesthesia”
because of the discrepant loss of sensory modalities. The sensory
deficit often is described as being in a “capelike” distribution over
the shoulders and arms. The anatomic basis for the neurologic
features of a syrinx is the location near the central canal. Crossing
fibers of the lateral spinothalamic tract carrying pain and temperature fibers may be impaired. Crude touch, position, and vibratory sensation typically are unaffected. Sensory fibers from the
lower limbs are similarly spared.
The symptoms of syringomyelia develop and progress in accordance with the intracavitary pressure and location of the syrinx.
The most common features on physical examination are lower
limb hyperreflexia, weakness and wasting in the hands and arms,
dissociated sensory loss, and gait disorder. Symptoms may be
exacerbated by a sneeze, cough, or Valsalva maneuver.49 Ninety
percent of patients with syringomyelia have Arnold-Chiari I malformation (projection of cerebellar tonsils and medulla into the
spinal canal).50 Syringomyelia also may result from spinal cord
trauma (often months to years later) or compressive tumors, or it
may follow meningitis.51
Diagnostic Strategies. Syringomyelia is best seen on MRI. No
other study currently in widespread use is equal to MRI in diagnostic ability.
Differential Considerations. Considerations in the differential
diagnosis for syrinx include intrinsic spinal tumor and
demyelination.
Management. When the diagnosis of syringomyelia is considered, emergent imaging in the ED is not necessary if follow-up
evaluation can be arranged because this condition usually is a
slowly progressive process. In patients for whom MRI studies are
obtained and the diagnosis is made, referral to a neurosurgeon is
indicated because symptoms progress in approximately two thirds
of patients.52
Spinal cord infarction is another diagnosis of exclusion. Aortic
dissection, surgery, and global ischemia are the more common
causes, although this disorder may occur as a complication of
systemic lupus erythematosus or may be cryptogenic. An anterior
spinal cord syndrome is the most common clinical picture. Some
recovery is possible, although it generally is less complete than in
cerebral stroke. The site of clinical dysfunction may be distant
from the site of vascular occlusion.58
Idiopathic spastic paraparesis is a progressive disorder characterized by progressive weakness and signs of spasticity of the lower
extremities. This condition sometimes also is referred to as
primary lateral sclerosis, which describes the demyelination
pattern in the lateral column of the spinal cord. This disorder
typically occurs in older men. A heritable form may sometimes be
discovered. It is a diagnosis of exclusion.53-55
Human Immunodeficiency Virus Myelopathy
HIV myelopathy typically occurs in patients with advanced
HIV disease. Weakness, gait disturbance, sphincter dysfunction,
sensory abnormalities, and signs of spasticity are features of this
progressive process. This is a diagnosis of exclusion because disorders such as toxoplasmosis, lymphoma, varicella-zoster, and
cytomegalovirus infection may produce a similar clinical picture
in immunocompromised patients. On pathologic examination,
vacuolization of myelin sheaths in the cord may be found. Treatment is directed at the retroviral infection, although there is no
proven treatment.56,57
Extrinsic Cord Lesions
Spinal Epidural Hematoma
Principles of Disease. Spinal epidural hematoma is a relatively rare
condition resulting from a variety of etiologic disorders. Its incidence is 0.1 per 100,000 population.59,60 The etiology may be traumatic after lumbar puncture, epidural anesthesia, or spinal
surgery.1,5,61 Spinal epidural hematoma is more likely to occur in
anticoagulated or thrombocytopenic patients or in patients with
liver disease or alcoholism.62 Spontaneous bleeding is rare but may
arise from spinal arteriovenous malformation or vertebral hemangioma. Approximately one fourth to one third of all cases are
associated with anticoagulation therapy, including low-molecularweight heparin.63,64
Clinical Features. The patient usually presents with sudden,
severe, constant back pain with a radicular component. It may be
noted to follow a straining episode. The pain may be worsened by
percussion over the spine and maneuvers that increase intraspinal
pressure, such as coughing, sneezing, or straining.65 The pain often
causes the patient to seek care before the development of neurologic signs, possibly leading to delays in diagnosis.5 Neurologic
deficits follow and may progress during hours to days.60 Anticoagulant use or an intrinsic coagulation abnormality may be present.
The patient usually is in significant distress from the pain.
Motor and sensory findings depend entirely on the level and size
of the hematoma but can include weakness, paresis, loss of bowel
or bladder function, and virtually any sensory deficit.
Diagnostic Strategies. MRI, as with virtually all suspected intrinsic spinal disorders, is the diagnostic study of choice.65
Differential Considerations. Considerations in the differential
diagnosis include abscess, epidural neoplasm, acute disk herniation, and spinal subarachnoid hemorrhage.
1426 PART III ◆ Medicine and Surgery / Section Seven • Neurology
Management. Recovery without surgery is rare, and surgical
consultation for emergent decompressive laminectomy should be
considered. The overall mortality rate is approximately 8%.60,65
Functional recovery is related primarily to the length of time the
symptoms are present. Recovery after 72 hours of symptoms is
rare but has been reported even without surgery.66,67
Spinal Epidural Abscess
Principles of Disease. Spinal epidural abscess is an infectious
process usually confined to the adipose tissue of the dorsal epidural space, where there is a rich venous plexus. It is an uncommon
disease, with an overall frequency of 0.2 to 1.2 per 10,000 hospital
admissions.68,69 Major risk factors include diabetes, injection drug
abuse, chronic renal failure, alcoholism, and immunosuppression,
although the disease can be seen in patients who have none of
these conditions.69-71 Whereas the disease may be manifested in
subacute and chronic forms, the acute presentation is seen most
frequently in the ED. Thoracic and lumbar sites of infection
predominate, with cervical epidural abscess being much less
common.72,73 Infection typically extends over four or five spinal
vertebral segments.74 The dura mater limits the spread of an epidural infection, making subdural or intraspinal spread uncommon. Hematogenous spread of infection to the epidural space is
the most common source (seen in 26-50% of cases),5,68,74 either to
the epidural space or to the vertebra with extension to the epidural
space. Skin and soft tissue infections are the most frequently
reported identified source (in 15%)70,74; Staphylococcus aureus is
the most prevalent organism, being cultured in more than 50% of
cases.68,75 Other frequently identified pathogens include aerobic
and anaerobic streptococci, Escherichia coli, and Pseudomonas
aeruginosa. Multiple organisms are identified in approximately
10% of cases; no organism is identified in 40%.65,72
Clinical Features. The classic clinical presentation of spinal epidural abscess begins with a backache that progresses to localized
back pain often associated with tenderness to percussion. The
duration of symptoms is typically a few days but may extend for
weeks. Fever, sweats, and rigors are common, being reported in 30
to 75% of patients.68,75 The classic triad of back pain, fever, and
progressive neurologic deficits is present in only a few patients,
however, and delayed clinical diagnosis is common.68 Radicular
symptoms may not be present initially but usually develop as the
disease progresses.
Without treatment, myelopathic signs will develop, usually
beginning with bowel and bladder disturbance. Weakness ensues,
followed by paraplegia or quadriplegia. Approximately 10% of
patients with spinal epidural abscess present with altered mental
status due to encephalopathy.68,74
Diagnostic Strategies. MRI is the imaging modality of choice
and needs to be performed emergently if the diagnosis is entertained. Other diagnostic testing is nonspecific for spinal epidural
abscess, but a complete blood count may support the diagnosis
because leukocytosis is commonly present, with a typical white
blood cell count of 13,000 to 16,000/µL.74 The erythrocyte sedimentation rate, although not specific for epidural abscess, is virtually always elevated with this condition.68,69,74 Plain films usually
are normal in appearance unless evidence of osteomyelitis of an
adjacent vertebral body is seen. Lumbar puncture is relatively contraindicated with known epidural abscess but is often performed
as part of the evaluation for meningitis. CSF findings are consistent with a parameningeal infection, showing elevation of protein
and some increase in inflammatory cells.
Differential Considerations. Any compressive spinal lesion,
including tumor or hematoma, can mimic spinal epidural abscess.
Management. Urgent surgical consultation for decompression
usually is required. Antibiotics effective against the most common
pathogens (particularly S. aureus) should be started empirically.
One such regimen that covers gram-positive and gram-negative
organisms consists of a third-generation cephalosporin plus vancomycin, both given intravenously, plus rifampin given orally.
Outcome is usually related to the speed of diagnosis before the
development of myelopathic signs. The disease is fatal in 18 to
23% of cases, and patients with neurologic deficit rarely improve
if surgical intervention is delayed more than 12 to 36 hours after
onset of paralysis.68,74 Patients operated on before development of
neurologic symptoms have an almost universally good outcome.69,70
Diskitis
Principles of Disease. Diskitis is an uncommon primary infection
of the nucleus pulposus, with secondary involvement of the cartilaginous endplate and vertebral body. It may occur after surgical
procedures or spontaneously, the latter being more common in
pediatric patients.76,77 An increased incidence of diskitis has been
noted in immunocompromised patients and in patients with systemic infections. Both a chronic disease and a more common
acute course have been described.76
Clinical Features. Patients present with moderate to severe pain,
localized to the level of involvement and exacerbated by almost
any movement of the spine. Radicular symptoms are present in 50
to 90% of cases.76,77 The lumbar spine is the most common site of
disease. Elevated temperature is noted in more than 90% of
patients.76 Patients experience pain with range of motion. Neurologic deficits are the exception with diskitis.
Diagnostic Strategies. Plain radiographs usually are not helpful
for early diagnosis, but destruction of the disk space is highly suggestive if present. The radiographic findings become abnormal
after 2 to 4 weeks of disease. In addition to disk space narrowing,
plain films may show irregular destruction of the vertebral body
endplates. Often there is a latent period (2 to 8 weeks) between
the onset of back pain and the development of other clinical
symptoms or abnormalities on the physical examination. MRI is
the radiographic study of choice because it can not only diagnose
diskitis but also rule out paravertebral or epidural abscess. Laboratory studies often show an elevated erythrocyte sedimentation
rate, but the white blood cell count usually is normal.76,77 S. aureus
is the most common pathogen, but gram-negative, fungal, and
tuberculous infections all have been recognized.
Differential Considerations. Considerations in the differential
diagnosis include vertebral osteomyelitis, spinal epidural abscess,
neoplasm, and hematoma.
Management. With timely diagnosis and treatment, outcome
generally is good, and medical treatment with intravenous antibiotics usually is curative. Surgery often is not necessary.76,77
Neoplasm
Principles of Disease. Spinal cord tumors are classified according
to their relationship to the dura and spinal cord (extradural, intradural extramedullary, and intradural intramedullary). Spinal cord
tumors produce neurologic symptoms by compression, invasion,
or destruction of myelinated tracts. The resulting neurologic
symptoms are directly related to the growth rate and the location
of the tumor. Spinal cord tumors account for 4 to 10% of central
nervous system tumors but for only 1% of all cancers. Primary
tumors occur with an incidence of 1 per 1 million population.78
Most tumors affecting the spinal cord are metastatic. Approximately 10% of patients with known cancer are diagnosed with a
spinal metastasis at some point in the course of their disease, and
5 to 10% of patients ultimately diagnosed with cancer first present
with a spinal metastasis.2 Lung cancer, breast cancer, and lymphoma represent more than 50% of the primary malignant
neoplasms that subsequently develop spinal metastasis, spreading
by both the hematogenous route and direct extension. Most
Chapter 106 / Spinal Cord Disorders 1427
metastases occur in the thoracic spine, and nearly 20% of patients
with tumor spread to the spine will be found to have disease at
multiple levels.2,79,80
Clinical Features. In 95% of patients with spinal neoplasm, the
initial complaint is pain, either in the back at the level of the tumor
or in a radicular distribution. Pain often is characterized as dull,
constant, and aching and commonly is said to worsen with recumbency (in contrast with the pain of herniated disk).5 Nighttime
pain that is severe is characteristic of spinal neoplasm.81 Any action
that increases intraspinal pressure (Valsalva maneuver, sneeze,
cough) may be associated with increased pain. Neurologic deficits
vary by the location of the lesion. Besides a thorough neurologic
examination, a search for possible primary sites should be done
on the physical examination.
Diagnostic Strategies. Plain radiographs are usually the initial
diagnostic test, and 70 to 85% of patients with spinal column
involvement show some abnormality on these films.81 Patients
with neurologic abnormalities and suspicious findings on plain
films are candidates for emergent MRI or CT myelography. In
patients with a known history of neoplasm and new back pain,
some authorities recommend foregoing plain films and proceeding directly to MRI because plain films can be misleading or
nondiagnostic.82
Differential Considerations. Considerations in the differential
diagnosis include any of the compressive lesions (hematoma,
infection). Tumor can also mimic intrinsic spinal cord lesions,
such as transverse myelopathy and cord infarction.
Management. Acute compressive myelopathy from neoplasm
constitutes an oncologic emergency. Immediate treatment is
required to preserve function and to prevent deterioration. With
onset of paraplegia and incontinence, less than 5% of patients
regain ambulatory status.1,83 Of patients who are ambulatory at
the time of diagnosis, 60% remain ambulatory.5 High-dose steroids, radiotherapy, and surgery all may be necessary acute interventions, and consultation with neurosurgeons, neurologists,
oncologists, and therapeutic radiologists may be required.
KEY CONCEPTS
■ Spinal cord disorders may be manifested in subtle fashion
and with nonspecific clinical signs and symptoms. In the
absence of neurologic abnormalities or complaints, diagnosis
of these disorders can be extremely difficult.
■ Patients with rapid onset and progression of spinal cord
symptoms should receive specialized imaging and
consultation in the ED.
■ MRI frequently is required for a definitive diagnosis of spinal
cord syndromes.
■ With compressive lesions of the spinal cord, duration of
neurologic dysfunction is directly related to ultimate
neurologic outcome. The diagnosis should be made
expeditiously and definitive therapy begun as soon as possible.
The references for this chapter can be found online by
accessing the accompanying Expert Consult website.
Chapter 106 / Spinal Cord Disorders 1427.e1
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