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6. Spine MCQs

Practice Set 332 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 6621

Topic: 6. Spine

On a lumbar MRI, what sagittal diameter of the spinal canal is generally considered indicative of absolute lumbar spinal stenosis?

. Greater than 15 mm.
. Between 13-15 mm.
. Less than 10 mm.
. Between 10-12 mm.
. Less than 8 mm.

Correct Answer & Explanation

. Less than 10 mm.

Explanation

While exact thresholds can vary slightly, a sagittal diameter of the lumbar spinal canal less than 10 mm is generally considered absolute stenosis, and 10-12 mm is considered relative stenosis. Values greater than 12 mm are typically considered normal. Therefore, 'less than 10 mm' (Option C) represents absolute stenosis.

Question 6622

Topic: 6. Spine

For a patient with symptomatic degenerative lumbar spinal stenosis, initial management should typically involve which of the following?

. Immediate surgical decompression.
. Corticosteroid injections into the facet joints.
. A trial of non-operative treatments including physical therapy and medication.
. Referral for psychological counseling only.
. Prescription of a rigid lumbar brace for long-term use.

Correct Answer & Explanation

. A trial of non-operative treatments including physical therapy and medication.

Explanation

The initial management for symptomatic degenerative lumbar spinal stenosis is overwhelmingly non-operative. This typically includes a trial of physical therapy (emphasizing flexion-based exercises), anti-inflammatory medications, activity modification, and sometimes epidural steroid injections. Surgery (Option A) is reserved for those who fail conservative management or develop severe neurological deficits. Facet joint injections (Option B) may be used if facet arthropathy is a significant pain generator, but not as initial primary treatment for stenosis itself. Options D and E are not initial primary treatments for the physical condition.

Question 6623

Topic: 6. Spine

Regarding lumbar epidural steroid injections for lumbar spinal stenosis, which statement is most accurate?

. They are curative for lumbar spinal stenosis.
. They have been shown to provide long-term pain relief (beyond 6 months) in the majority of patients.
. They can provide short-term symptomatic relief but have limited evidence for long-term efficacy.
. They are contraindicated in patients with diabetes mellitus.
. Transforaminal injections are generally less effective than interlaminar injections.

Correct Answer & Explanation

. They can provide short-term symptomatic relief but have limited evidence for long-term efficacy.

Explanation

Lumbar epidural steroid injections (ESIs) can provide significant short-term (weeks to a few months) symptomatic relief by reducing inflammation around the compressed nerve roots. However, there is limited evidence for their long-term efficacy (beyond 6 months), and they are not considered curative. They are not contraindicated in diabetics (Option D), though blood sugar levels need to be monitored. Transforaminal injections (Option E) are often considered more targeted and effective than interlaminar injections for radicular pain, making Option E incorrect. ESIs are palliative, not curative (Option A).

Question 6624

Topic: 6. Spine

What is a potential advantage of minimally invasive lumbar decompression (e.g., tubular microdecompression) compared to traditional open laminectomy for spinal stenosis?

. Greater extent of decompression possible.
. Higher rate of successful fusion.
. Reduced muscle damage and faster recovery.
. Lower risk of dural tear.
. Improved long-term clinical outcomes compared to open surgery.

Correct Answer & Explanation

. Reduced muscle damage and faster recovery.

Explanation

Minimally invasive lumbar decompression techniques aim to reduce soft tissue disruption (e.g., muscle damage, blood loss) compared to traditional open laminectomy. This often leads to less postoperative pain, shorter hospital stays, and a faster return to activity, i.e., reduced muscle damage and faster recovery. The extent of decompression (Option A) should ideally be equivalent. MIS approaches alone do not involve fusion (Option B). The risk of dural tear (Option D) may actually be similar or even slightly higher with less familiar MIS techniques. Long-term clinical outcomes (Option E) are generally comparable to open surgery, but with the short-term recovery advantages.

Question 6625

Topic: 6. Spine

Following an uncomplicated single-level lumbar decompression for spinal stenosis, when is typically the earliest a patient can resume light activity and progressive ambulation?

. After 6 weeks of strict bed rest.
. Within 24-48 hours post-surgery.
. Only after radiographic confirmation of bone healing at 3 months.
. After completing 6 months of intense rehabilitation.
. Not until 1 year post-op to prevent recurrence.

Correct Answer & Explanation

. Within 24-48 hours post-surgery.

Explanation

For an uncomplicated lumbar decompression, early mobilization and progressive ambulation are encouraged, often within 24-48 hours post-surgery. This helps prevent complications like DVT and promotes recovery. Strict bed rest (Option A) is detrimental. Radiographic bone healing (Option C) is relevant for fusion, not typically for decompression alone. Options D and E are excessively long and delay recovery.

Question 6626

Topic: 6. Spine

Which factor is generally associated with a poorer surgical outcome in patients undergoing decompression for lumbar spinal stenosis?

. Single-level stenosis.
. Presence of stable degenerative spondylolisthesis.
. Significant obesity and multiple comorbidities.
. Age greater than 75 years.
. Severe preoperative neurogenic claudication.

Correct Answer & Explanation

. Significant obesity and multiple comorbidities.

Explanation

Significant obesity and multiple comorbidities (e.g., uncontrolled diabetes, severe cardiovascular disease, chronic obstructive pulmonary disease) are consistently associated with higher surgical risks, increased complication rates, and potentially poorer functional outcomes. Single-level stenosis (Option A) usually has better outcomes than multilevel. Stable degenerative spondylolisthesis (Option B) can be successfully managed. Advanced age (Option D) alone is not a contraindication, and outcomes can be good. Severe preoperative claudication (Option E) often correlates with significant improvement after successful decompression.

Question 6627

Topic: 6. Spine

How does adult degenerative scoliosis typically contribute to the development of lumbar spinal stenosis?

. It causes generalized spinal canal widening.
. It primarily leads to disc desiccation and collapse, causing direct stenosis.
. It results in asymmetric facet hypertrophy, ligamentum flavum hypertrophy, and segmental rotation, narrowing the canal.
. It typically shifts the center of gravity anteriorly, decompressing the posterior elements.
. It causes kyphosis, which improves the sagittal alignment and canal dimensions.

Correct Answer & Explanation

. It results in asymmetric facet hypertrophy, ligamentum flavum hypertrophy, and segmental rotation, narrowing the canal.

Explanation

Adult degenerative scoliosis contributes to spinal stenosis through a combination of asymmetric degenerative changes. This includes asymmetric facet joint hypertrophy, ligamentum flavum hypertrophy, and rotational subluxation of vertebrae, all of which narrow the spinal canal and neural foramina, particularly on the concave side of the curve. Option A is incorrect. Disc desiccation and collapse (Option B) are part of the degenerative process but the scoliosis adds further specific mechanisms. Option D and E are incorrect as scoliosis typically leads to sagittal imbalance and further compression.

Question 6628

Topic: 6. Spine

While severe central lumbar stenosis can lead to cauda equina syndrome, true spinal cord myelopathy with upper motor neuron signs would NOT be expected in isolated lumbar spinal stenosis. Which of the following is a classic sign of upper motor neuron dysfunction?

. Hyporeflexia.
. Flaccid paralysis.
. Positive Babinski sign.
. Muscle atrophy (late stage).
. Fasciculations.

Correct Answer & Explanation

. Positive Babinski sign.

Explanation

A positive Babinski sign (extensor plantar response) is a classic sign of upper motor neuron (UMN) dysfunction, indicating a lesion in the corticospinal tract. The other options (hyporeflexia, flaccid paralysis, muscle atrophy, fasciculations) are characteristic of lower motor neuron (LMN) dysfunction, which is what would be seen in cauda equina syndrome resulting from severe lumbar spinal stenosis. True myelopathy occurs in the cervical or thoracic spine, where the spinal cord itself is present.

Question 6629

Topic: 6. Spine

What is the principle behind 'indirect decompression' for lumbar spinal stenosis?

. Direct removal of stenotic bone and ligamentum flavum.
. Placement of a spacer between spinous processes to maintain extension.
. Restoration of disc height and lumbar lordosis via fusion, thereby enlarging the canal indirectly.
. Decompression performed through an endoscopic approach.
. Application of external traction to distract the spinal segments.

Correct Answer & Explanation

. Restoration of disc height and lumbar lordosis via fusion, thereby enlarging the canal indirectly.

Explanation

Indirect decompression refers to surgical techniques that enlarge the spinal canal and neural foramina without directly removing posterior osteoligamentous structures. This is typically achieved by restoring disc height and lumbar lordosis, often through fusion procedures (e.g., TLIF, PLIF, LLIF). By restoring disc height, the tension on the ligamentum flavum is increased, and the foraminal height is increased, effectively decompressing the neural elements indirectly. Direct removal (Option A) is direct decompression. Spinous process spacers (Option B) primarily restrict extension. Endoscopic approaches (Option D) are a type of direct decompression. Traction (Option E) is a conservative measure.

Question 6630

Topic: 6. Spine

What is the primary utility of dynamic flexion-extension radiographs in the workup of lumbar spinal stenosis?

. To assess the degree of spinal canal narrowing.
. To visualize soft tissue compression of nerve roots.
. To detect spinal instability (e.g., degenerative spondylolisthesis movement).
. To identify the presence of disc herniation.
. To measure facet joint hypertrophy.

Correct Answer & Explanation

. To detect spinal instability (e.g., degenerative spondylolisthesis movement).

Explanation

Dynamic flexion-extension radiographs are primarily used to assess for spinal instability, particularly the presence of degenerative spondylolisthesis that exhibits abnormal translation or angulation with movement. This instability can influence the decision to perform adjunctive fusion during decompression. The degree of canal narrowing (Option A) and soft tissue compression (Option B) are best assessed by MRI. Disc herniation (Option D) and facet hypertrophy (Option E) are also best seen on MRI or CT.

Question 6631

Topic: 6. Spine

In a patient with degenerative lumbar spinal stenosis and an associated Grade I degenerative spondylolisthesis, what impact does the spondylolisthesis generally have on surgical decision-making?

. It contraindicates surgical decompression.
. It always necessitates fusion in addition to decompression.
. It typically leads to better outcomes with decompression alone.
. It may increase the likelihood of fusion if there is evidence of instability or anticipated iatrogenic instability.
. It requires a more extensive laminectomy than isolated stenosis.

Correct Answer & Explanation

. It may increase the likelihood of fusion if there is evidence of instability or anticipated iatrogenic instability.

Explanation

The presence of a Grade I degenerative spondylolisthesis, particularly if it is unstable (dynamic movement on flexion-extension views) or if a wide decompression is anticipated to destabilize the segment, often indicates the need for adjunctive fusion. Decompression alone without fusion in an unstable segment may lead to increased instability and continued pain. It does not contraindicate surgery (Option A), nor does italwaysnecessitate fusion if stable (Option B). Decompression alone in unstable spondylolisthesis may lead to poorer outcomes (Option C). A more extensive laminectomy (Option E) is not directly related to the spondylolisthesis itself, but rather to the degree of stenosis.

Question 6632

Topic: 6. Spine

Which of the following is an absolute contraindication to elective lumbar decompression surgery for spinal stenosis?

. Age greater than 80 years.
. Controlled diabetes mellitus.
. Severe untreated coagulopathy.
. Multilevel stenosis (3 or more levels).
. Mild neurogenic claudication symptoms.

Correct Answer & Explanation

. Severe untreated coagulopathy.

Explanation

Severe untreated coagulopathy is an absolute contraindication to elective spinal surgery due to the high risk of catastrophic hemorrhage, epidural hematoma formation, and other bleeding complications. Age (Option A) and controlled diabetes (Option B) are relative contraindications or risk factors, but not absolute contraindications. Multilevel stenosis (Option D) can be more complex but is not an absolute contraindication. Mild symptoms (Option E) suggest conservative management is appropriate, not that surgery is contraindicated when indicated.

Question 6633

Topic: 6. Spine

What is the primary mechanism by which surgical decompression alleviates symptoms in lumbar spinal stenosis?

. By regenerating damaged nerve tissue.
. By directly reducing inflammation around the nerve roots.
. By removing mechanical compression on the cauda equina nerve roots.
. By altering pain perception in the brain.
. By strengthening the muscles surrounding the lumbar spine.

Correct Answer & Explanation

. By removing mechanical compression on the cauda equina nerve roots.

Explanation

Surgical decompression primarily alleviates symptoms by physically removing the mechanical impediments (hypertrophied ligamentum flavum, osteophytes, disc bulges) that are compressing the cauda equina nerve roots. This directly restores space within the spinal canal and neuroforamina, allowing for improved blood flow and nerve function. While secondary reduction in inflammation may occur (Option B) and muscle strengthening (Option E) is a goal of rehabilitation, the fundamental mechanism is the removal of mechanical compression. Nerve tissue regeneration (Option A) is generally not possible, and altering pain perception (Option D) is not the primary surgical mechanism.

Question 6634

Topic: 6. Spine
When considering surgery for lumbar spinal stenosis in an elderly patient (e.g., >80 years old), which of the following statements is most accurate regarding outcomes?
. Surgery is generally contraindicated due to high complication rates and poor outcomes.
. Outcomes are universally worse than in younger patients, with no significant improvement in quality of life.
. While complication rates may be slightly higher, carefully selected elderly patients can achieve significant pain relief and functional improvement.
. Elderly patients are more likely to require fusion after decompression due to inherent instability.
. Conservative management is always preferred, regardless of symptom severity.

Correct Answer & Explanation

. While complication rates may be slightly higher, carefully selected elderly patients can achieve significant pain relief and functional improvement.

Explanation

Multiple studies have shown that carefully selected elderly patients (even those >80 years old) can achieve significant pain relief and functional improvement from lumbar decompression for spinal stenosis, comparable to younger cohorts. While complication rates may be marginally higher due to comorbidities, age alone is not a contraindication. Options A and B are overly pessimistic. Option D is not universally true; instability rather than age itself dictates the need for fusion. Conservative management (Option E) should always be attempted first, but if symptoms are debilitating and fail conservative care, surgery remains a viable and often beneficial option.

Question 6635

Topic: 6. Spine

How does hypertrophy of the ligamentum flavum contribute to lumbar spinal stenosis?

. It causes direct anterior compression of the dural sac.
. It stiffens the spinal column, preventing flexion.
. It buckles and thickens posteriorly and posterolaterally, reducing the sagittal and transverse diameters of the spinal canal.
. It leads to increased elasticity, providing less support to the vertebral column.
. It promotes disc space narrowing, indirectly causing stenosis.

Correct Answer & Explanation

. It buckles and thickens posteriorly and posterolaterally, reducing the sagittal and transverse diameters of the spinal canal.

Explanation

Hypertrophy of the ligamentum flavum is a major contributor to lumbar spinal stenosis. As the ligament thickens and buckles inward, particularly with extension, it directly encroaches upon the posterior aspect of the spinal canal, reducing its sagittal and transverse diameters and compressing the cauda equina nerve roots. Options A, D, and E are incorrect. While it stiffens the column (Option B), this is not its primary contribution to stenosis; rather, its physical bulk is the issue.

Question 6636

Topic: 6. Spine

At which vertebral level does the conus medullaris typically terminate in adults, marking the transition from spinal cord to cauda equina?

. T10-T11.
. T12-L1.
. L2-L3.
. L4-L5.
. S1-S2.

Correct Answer & Explanation

. T12-L1.

Explanation

In the vast majority of adults, the conus medullaris (the caudal end of the spinal cord) typically terminates at the T12-L1 vertebral level, though it can range from T11 to L2. Below this level, the spinal canal contains only the cauda equina nerve roots. This is a critical anatomical landmark for understanding why lumbar stenosis causes cauda equina syndrome, not true myelopathy.

Question 6637

Topic: 6. Spine

A patient experiences persistent or recurrent symptoms after lumbar decompression for spinal stenosis. What is the most common cause of 'failed back surgery syndrome' (FBSS) in this context?

. New disc herniation at a different level.
. Development of a spinal tumor.
. Recurrent stenosis due to inadequate decompression or progressive degeneration.
. Infection of the surgical site.
. Peripheral neuropathy unrelated to the surgery.

Correct Answer & Explanation

. Recurrent stenosis due to inadequate decompression or progressive degeneration.

Explanation

The most common cause of 'failed back surgery syndrome' (FBSS) in the context of lumbar spinal stenosis is recurrent stenosis. This can be due to inadequate initial decompression, stenosis at an adjacent level (adjacent segment disease), or progressive degenerative changes over time at the treated or adjacent levels. While other options can occur, recurrent stenosis is the leading cause for persistent/recurrent symptoms post-decompression for stenosis.

Question 6638

Topic: 6. Spine

Interspinous process decompression devices (e.g., X-Stop) are designed to achieve what primary effect in patients with lumbar spinal stenosis?

. To fuse adjacent vertebral bodies.
. To directly remove hypertrophied ligamentum flavum.
. To limit lumbar extension and maintain a slight flexion posture, thereby increasing the spinal canal diameter.
. To replace degenerated intervertebral discs.
. To stabilize a segment with significant spondylolisthesis.

Correct Answer & Explanation

. To limit lumbar extension and maintain a slight flexion posture, thereby increasing the spinal canal diameter.

Explanation

Interspinous process devices are designed to act as spacers between the spinous processes. By maintaining a slightly flexed or neutral lumbar posture, they prevent excessive extension. Lumbar extension typically narrows the spinal canal, so by limiting extension, these devices indirectly help to increase the sagittal diameter of the canal and relieve pressure on the neural elements. They do not fuse segments (Option A), directly remove tissue (Option B), replace discs (Option D), or stabilize significant spondylolisthesis (Option E).

Question 6639

Topic: 6. Spine

What is generally understood about the natural history of symptomatic lumbar spinal stenosis managed non-operatively?

. The majority of patients experience progressive, debilitating neurological deficits over time.
. Symptoms invariably worsen, requiring surgery within 1-2 years.
. Many patients experience stable or mildly worsening symptoms, and some may even improve, with only a minority progressing to severe disability.
. Complete resolution of symptoms is common with long-term conservative care.
. The condition always progresses to cauda equina syndrome if not surgically treated.

Correct Answer & Explanation

. Many patients experience stable or mildly worsening symptoms, and some may even improve, with only a minority progressing to severe disability.

Explanation

The natural history of lumbar spinal stenosis is often benign. Many patients experience stable symptoms, some may have periods of improvement, and only a minority progress to severe neurological deficits or require surgery. The progression is typically slow, and not all patients with symptomatic stenosis require surgery. Options A, B, and E are overly pessimistic. Complete resolution (Option D) is less common, but significant improvement can occur.

Question 6640

Topic: 6. Spine

In which specific clinical scenario would a CT myelogram be preferred over an MRI for evaluating lumbar spinal stenosis?

. Routine initial evaluation of uncomplicated stenosis.
. Suspected soft tissue tumor in the spinal canal.
. Patients with significant ferromagnetic implants (e.g., pacemakers, certain spinal hardware) contraindicating MRI.
. Assessment of disc herniation severity.
. Evaluation of spinal cord edema.

Correct Answer & Explanation

. Patients with significant ferromagnetic implants (e.g., pacemakers, certain spinal hardware) contraindicating MRI.

Explanation

CT myelography is typically preferred over MRI when MRI is contraindicated due to the presence of significant ferromagnetic implants (e.g., pacemakers, certain older spinal hardware, some cochlear implants) or in patients who cannot tolerate MRI (e.g., severe claustrophobia, extreme obesity). While MRI is generally superior for soft tissue, a CT myelogram provides excellent visualization of the neural elements and canal dimensions after intrathecal contrast injection. Routine initial evaluation (Option A), soft tissue tumors (Option B), disc herniation (Option D), and spinal cord edema (Option E) are best evaluated by MRI.

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