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6. Spine MCQs

Practice Set 295 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 5881

Topic: 6. Spine

A 10-year-old boy with SMA Type II presents with severe, progressive paralytic scoliosis measuring 85 degrees. He is currently receiving intrathecal Nusinersen therapy every 4 months. When planning posterior spinal fusion for this patient, which critical technical modification must be considered?

. Using sublaminar wires exclusively instead of pedicle screws
. Performing an anterior release prior to posterior instrumentation
. Leaving an interlaminar window or creating a lumbar port for future intrathecal access
. Extending the fusion to the cervical spine to prevent proximal junctional kyphosis
. Avoiding the use of any local bone graft due to inherent SMN1 mutations in osteoblasts

Correct Answer & Explanation

. Leaving an interlaminar window or creating a lumbar port for future intrathecal access

Explanation

Nusinersen is administered via intrathecal injection. In patients undergoing spinal fusion, the surgeon must leave a targeted interlaminar window (usually around L3-L4) or implant an intrathecal catheter/port to allow for continued drug administration.

Question 5882

Topic: 6. Spine

A 14-year-old with Osteogenesis Imperfecta Type IV presents with hyperreflexia, ataxia, and a new-onset headache exacerbated by coughing. Which of the following imaging modalities is the most appropriate next step in evaluation?

. Anteroposterior and lateral radiographs of the thoracic spine
. CT scan of the temporal bones
. Sagittal MRI of the craniocervical junction
. DEXA scan of the lumbar spine
. Dynamic fluoroscopy of the cervical spine

Correct Answer & Explanation

. Sagittal MRI of the craniocervical junction

Explanation

The patient's symptoms suggest basilar invagination, a dangerous complication common in OI (particularly Type IV). Sagittal MRI of the craniocervical junction is the gold standard to evaluate for brainstem compression.

Question 5883

Topic: 6. Spine

A 10-year-old girl with SMA Type II presents with an increasingly collapsing spine.

A custom Thoracolumbosacral Orthosis (TLSO) is prescribed. What is the primary expectation regarding the use of this brace?

. It will halt the progression of the scoliotic curve until skeletal maturity.
. It will correct the structural deformity of the spine over time.
. It will improve seating balance and posture but will not alter the natural progression of the curve.
. It will improve pulmonary function parameters by increasing chest wall compliance.
. It serves as a definitive alternative to posterior spinal fusion.

Correct Answer & Explanation

. It will improve seating balance and posture but will not alter the natural progression of the curve.

Explanation

Bracing in neuromuscular scoliosis (like SMA) is palliative. It helps support the collapsing spine, freeing the upper extremities for function and improving sitting posture, but it does not prevent or stop the progression of the scoliotic curve.

Question 5884

Topic: 6. Spine

In patients with Spinal Muscular Atrophy, the primary pathological process affecting the nervous system is characterized by which of the following?

. Demyelination of the peripheral sensory nerves
. Apoptosis of lower motor neurons in the anterior horn of the spinal cord
. Degeneration of the upper motor neurons in the primary motor cortex
. Inflammatory infiltration of the neuromuscular junction
. Ischemic necrosis of the dorsal root ganglia

Correct Answer & Explanation

. Apoptosis of lower motor neurons in the anterior horn of the spinal cord

Explanation

SMA is an autosomal recessive neurodegenerative disease characterized by the progressive apoptosis (loss) of lower motor neurons in the anterior horn of the spinal cord, leading to progressive muscle weakness and atrophy.

Question 5885

Topic: 6. Spine

A 4-year-old child with achondroplasia presents with progressive weakness in all four extremities, new-onset hyperreflexia, and frequent episodes of central sleep apnea. What is the most appropriate imaging study to evaluate the underlying cause of these symptoms?

. Flexion-extension radiographs of the cervical spine
. MRI of the craniovertebral junction
. CT scan of the lumbar spine
. MRI of the thoracic spine
. Somatosensory evoked potentials (SSEPs)

Correct Answer & Explanation

. MRI of the craniovertebral junction

Explanation

The symptoms described point to high cervical myelopathy and lower brainstem compression, which in young children with achondroplasia is typically caused by foramen magnum stenosis. MRI of the craniovertebral junction is the imaging modality of choice to evaluate the extent of neural compression.

Question 5886

Topic: Thoracolumbar Spine & Deformity
A 12-year-old competitive gymnast presents with severe low back pain and radicular pain radiating down her posterior left leg. Lateral radiographs demonstrate a Meyerding Grade IV isthmic spondylolisthesis at L5-S1 with a slip angle of 55 degrees. What is the most appropriate surgical treatment?
. L5-S1 posterior in situ fusion without decompression
. L5 laminectomy and direct repair of the pars defect
. L4-S1 posterior instrumented fusion with partial reduction and decompression
. Anterior lumbar interbody fusion (ALIF) alone
. Physical therapy, bracing for 6 months, and activity modification

Correct Answer & Explanation

. L4-S1 posterior instrumented fusion with partial reduction and decompression

Explanation

High-grade spondylolisthesis (Meyerding Grade III-V) with radicular symptoms and a high slip angle (>40-50 degrees) carries a high risk of progression and pseudarthrosis if treated with in situ fusion. The standard of care is decompression of the compressed nerve roots, partial reduction of the slip angle, and posterior instrumented fusion, typically extending from L4 to S1.

Question 5887

Topic: Thoracolumbar Spine & Deformity

In the evaluation of pediatric developmental (isthmic) spondylolisthesis at L5-S1, which of the following spinopelvic parameters is most strongly associated with an increased risk of severe slip progression?

. Decreased pelvic incidence
. Increased pelvic incidence
. Decreased sacral slope
. Increased thoracic kyphosis
. Decreased lumbar lordosis

Correct Answer & Explanation

. Increased pelvic incidence

Explanation

Pelvic Incidence (PI) is an anatomical spinopelvic parameter that is fixed after skeletal maturity. A high PI results in a high shear stress at the lumbosacral junction. Patients with developmental, high-grade spondylolisthesis almost universally have a significantly higher pelvic incidence compared to the general population, which drives slip progression.

Question 5888

Topic: 6. Spine

A 14-year-old boy presents with progressive mid-back pain. Lateral radiographs of his thoracic spine reveal rigid hyperkyphosis. According to the Sorensen criteria for classical Scheuermann's disease, what is the required radiographic threshold regarding vertebral body wedging?

. Anterior wedging of > 5 degrees in one isolated vertebra
. Anterior wedging of > 5 degrees in at least three adjacent vertebrae
. Endplate irregularities with preserved disc spaces
. Disc space narrowing of > 50% at three contiguous levels
. A total kyphosis angle of > 50 degrees with a flexible apex

Correct Answer & Explanation

. Anterior wedging of > 5 degrees in at least three adjacent vertebrae

Explanation

The diagnosis of classic Scheuermann's kyphosis using Sorensen criteria requires anterior wedging of greater than 5 degrees in at least three adjacent (contiguous) vertebral bodies. Other classic radiographic signs include Schmorl's nodes, endplate irregularities, and narrowed disc spaces, but the contiguous wedging is the definitive diagnostic criterion.

Question 5889

Topic: Cervical Spine

A 7-year-old girl presents with severe torticollis, neck pain, and a 'cock-robin' head position three weeks after undergoing a tonsillectomy. Radiographs show an increased atlantodens interval. In the pathogenesis of Grisel's syndrome, what is the primary mechanism leading to this atlantoaxial subluxation?

. Direct bacterial invasion of the facet joints causing septic arthritis
. Ischemic necrosis of the dens from disruption of the apical artery
. Hyperemic decalcification and laxity of the transverse ligament
. Traumatic rupture of the alar ligaments during endotracheal intubation
. Congenital absence of the apical ligament unmasked by surgery

Correct Answer & Explanation

. Hyperemic decalcification and laxity of the transverse ligament

Explanation

Grisel's syndrome is a non-traumatic atlantoaxial rotatory subluxation associated with head and neck infections (or postoperative states like tonsillectomy/adenoidectomy). The robust venous plexus draining the retropharyngeal space communicates directly with the periodontoid vascular plexus. Inflammatory hyperemia spreads to the periodontoid tissues, causing decalcification of the anterior arch of C1 and subsequent laxity of the transverse ligament, leading to subluxation.

Question 5890

Topic: 6. Spine

A 12-year-old boy with Duchenne Muscular Dystrophy (DMD) has lost independent ambulation and presents with a progressive neuromuscular scoliosis of 28 degrees. When counseling the family regarding posterior spinal fusion to the pelvis, what are the standard criteria for proceeding with surgery to optimize outcomes and minimize prohibitive respiratory complications?

. Cobb angle > 20 degrees and Forced Vital Capacity (FVC) > 35%
. Cobb angle > 40 degrees and Forced Vital Capacity (FVC) < 20%
. Cobb angle > 50 degrees regardless of Forced Vital Capacity
. Cobb angle > 10 degrees and loss of ambulation
. Painful scoliosis and Forced Vital Capacity (FVC) < 15%

Correct Answer & Explanation

. Cobb angle > 20 degrees and Forced Vital Capacity (FVC) > 35%

Explanation

In Duchenne Muscular Dystrophy, scoliosis progresses rapidly once ambulation is lost. To prevent severe deformity and restrictive lung disease, surgical intervention (posterior spinal fusion from the upper thoracic spine to the pelvis) is indicated early, typically when the Cobb angle reaches 20 to 30 degrees. The surgery must be performed while the patient's respiratory function is adequate; specifically, a Forced Vital Capacity (FVC) > 35% is generally required, as operating when FVC falls below 30-35% carries a prohibitively high risk of postoperative ventilator dependence and mortality.

Question 5891

Topic: Thoracolumbar Spine & Deformity
A 14-year-old female gymnast presents with severe lower back pain radiating down the posterior aspect of both thighs. Radiographs demonstrate a Grade III L5-S1 isthmic spondylolisthesis. Her pelvic incidence is 75 degrees and her slip angle is 50 degrees. She has failed 6 months of conservative management. What is the most appropriate surgical treatment?
. L5 pars interarticularis repair
. L5-S1 anterior lumbar interbody fusion (ALIF) only
. In situ L5-S1 posterolateral fusion without instrumentation
. L4-S1 posterior instrumented reduction and fusion with interbody support
. L5 complete laminectomy without fusion

Correct Answer & Explanation

. L4-S1 posterior instrumented reduction and fusion with interbody support

Explanation

This patient has a high-grade (Grade III) isthmic spondylolisthesis with high pelvic incidence and a high slip angle, all of which indicate severe sagittal imbalance and a high risk of progression. High-grade slips typically require posterior instrumented fusion extending to L4 (L4-S1), often with reduction and interbody support (ALIF or TLIF) to correct the severe slip angle, improve sagittal balance, and increase fusion rates. A simple pars repair is only appropriate for early Grade I slips without significant listhesis, and isolated in situ fusion for high-grade slips carries unacceptably high pseudoarthrosis rates.

Question 5892

Topic: 6. Spine

A 6-month-old infant is noted to have a left thoracic curve of 25 degrees on a supine radiograph. The rib-vertebral angle difference (RVAD) of Mehta is measured at 28 degrees. What is the most likely clinical course and appropriate management?

. Spontaneous resolution; observation
. High risk of progression; serial Mehta casting
. High risk of progression; immediate posterior spinal fusion
. Low risk of progression; TLSO bracing
. High association with tethered cord; MRI of the whole spine

Correct Answer & Explanation

. High risk of progression; serial Mehta casting

Explanation

In infantile idiopathic scoliosis, an RVAD (Mehta angle) greater than 20 degrees indicates a high risk of progressive deformity. Early serial elongation-derotation-flexion (EDF) casting is the gold standard treatment for progressive infantile curves.

Question 5893

Topic: 6. Spine

A 35-year-old male presents with sudden-onset, severe right shoulder pain that awakened him from sleep. The acute severe pain lasted for 5 days and then gradually subsided, but was immediately followed by profound weakness in shoulder elevation and external rotation. An MRI of the cervical spine and shoulder is unremarkable.

What is the most likely diagnosis?

. Acute cervical radiculopathy (C5-C6)
. Parsonage-Turner Syndrome
. Massive acute rotator cuff tear
. Quadrilateral space syndrome
. Suprascapular nerve entrapment by a spinoglenoid ganglion

Correct Answer & Explanation

. Parsonage-Turner Syndrome

Explanation

Parsonage-Turner Syndrome (acute brachial neuritis) classically presents with severe, unrelenting, acute shoulder pain (often worse at night) lasting days to weeks, followed by patchy, profound weakness and muscle atrophy (most commonly affecting the suprascapular, axillary, or long thoracic nerves) as the pain subsides. It is often preceded by a viral illness or vaccination. MRI is typically normal initially but may show denervation edema in the affected muscles later. Treatment is primarily conservative with NSAIDs, steroids, and physical therapy.

Question 5894

Topic: 6. Spine
A 22-year-old male presents after a diving accident. Cervical spine imaging reveals a traumatic spondylolisthesis of the axis (Hangman's fracture). The fracture demonstrates severe angulation but minimal translation, consistent with a Levine-Edwards Type IIA injury. Which of the following interventions is strictly contraindicated in the acute management of this specific fracture pattern?
. Application of cervical traction
. Placement in a rigid cervical collar
. Application of a Halo vest with slight compression
. Surgical fixation using C2 pars screws
. Surgical fixation using a C2-C3 anterior cervical discectomy and fusion

Correct Answer & Explanation

. Application of a Halo vest with slight compression

Explanation

The Levine-Edwards Type IIA Hangman's fracture is caused by flexion-distraction forces. It is characterized by severe angulation with minimal translation. Because the mechanism involves distraction and injury to the posterior longitudinal ligament and C2-C3 disc, the application of cervical traction is strictly contraindicated as it will exacerbate the deformity and over-distract the spine. Treatment is typically a Halo vest applied with slight extension and compression.

Question 5895

Topic: 6. Spine

The anterior (Smith-Robinson) approach to the cervical spine allows access from C3 to T1. The internervous plane utilized in this approach lies between muscles innervated by which two nerves?

. Spinal accessory nerve and Ansa cervicalis
. Vagus nerve and Hypoglossal nerve
. Recurrent laryngeal nerve and Phrenic nerve
. Cervical plexus branches and Facial nerve
. Ansa cervicalis and Recurrent laryngeal nerve

Correct Answer & Explanation

. Spinal accessory nerve and Ansa cervicalis

Explanation

The anterior approach to the cervical spine goes between the sternocleidomastoid muscle laterally (innervated by the spinal accessory nerve, CN XI) and the strap muscles medially (sternohyoid, sternothyroid, omohyoid), which are innervated by the ansa cervicalis. The recurrent laryngeal nerve is a critical structure at risk, particularly on the right side due to its more variable and oblique course.

Question 5896

Topic: 6. Spine

An anterior approach to the cervical spine (Smith-Robinson) is performed at the C5-C6 level. The dissection passes medial to the carotid sheath and lateral to the visceral axis (trachea/esophagus). Which of the following fascial layers must be divided to enter the retropharyngeal space and access the longus colli muscles?

. Superficial cervical fascia
. Investing fascia
. Pretracheal fascia
. Alar fascia
. Prevertebral fascia

Correct Answer & Explanation

. Prevertebral fascia

Explanation

After splitting the platysma (superficial fascia) and passing the investing fascia, the dissection retracts the pretracheal fascia/visceral structures medially and the carotid sheath laterally. The prevertebral fascia lies immediately anterior to the longus colli muscles and the cervical spine and must be incised to expose the vertebral bodies.

Question 5897

Topic: 6. Spine

A patient with Spondyloepiphyseal Dysplasia Congenita (SEDC) requires preoperative clearance for lower extremity osteotomies. Which of the following preoperative imaging studies is most critical for this patient?

. MRI of the entire neuroaxis
. Echocardiogram
. Flexion-extension radiographs of the cervical spine
. CT of the chest and abdomen
. DEXA scan

Correct Answer & Explanation

. Flexion-extension radiographs of the cervical spine

Explanation

SEDC is associated with odontoid hypoplasia and atlantoaxial instability. Cervical spine clearance is mandatory before any procedure requiring anesthesia or intubation.

Question 5898

Topic: 6. Spine

A 16-year-old male presents with painful, progressive scoliosis. Imaging confirms the presence of an osteoid osteoma in the lumbar spine.

Where is this lesion most typically located relative to the scoliotic deformity?

. On the apex of the convexity
. On the apex of the concavity
. Two levels cephalad to the apex
. On the anterior vertebral body of the compensatory curve
. Symmetrically distributed on both sides of the lamina

Correct Answer & Explanation

. On the apex of the concavity

Explanation

In cases of scoliosis secondary to an osteoid osteoma, the lesion is almost exclusively found at the apex of the concavity. The intense inflammatory response causes asymmetric muscle spasm, pulling the spine toward the side of the lesion.

Question 5899

Topic: Cervical Spine

A 65-year-old female with an 18-year history of rheumatoid arthritis is being evaluated prior to a total knee arthroplasty. Flexion-extension cervical spine radiographs reveal a 9 mm anterior atlanto-dens interval (ADI). What pathomechanical process is primarily responsible for this finding?

. Traumatic fracture of the odontoid process
. Synovial pannus destruction of the transverse ligament
. Degenerative disc disease causing C1-C2 autofusion
. Ischemic necrosis of the apical ligament
. Congenital hypoplasia of the dens

Correct Answer & Explanation

. Synovial pannus destruction of the transverse ligament

Explanation

Atlantoaxial subluxation is the most common cervical spine manifestation of Rheumatoid Arthritis. It is caused by synovial pannus formation in the retro-odontoid bursa, which subsequently destroys the transverse ligament of the atlas.

Question 5900

Topic: 6. Spine

A 9-month-old infant with diagnosed achondroplasia presents with central sleep apnea, progressive lower extremity weakness, and hyperreflexia. What is the most likely anatomic etiology of these neurological symptoms?

. Thoracolumbar kyphosis
. Foramen magnum stenosis
. Atlantoaxial instability
. Lumbar spinal stenosis
. Tethered spinal cord

Correct Answer & Explanation

. Foramen magnum stenosis

Explanation

Foramen magnum stenosis is a critical and potentially life-threatening complication in infants and toddlers with achondroplasia. It can compress the cervicomedullary junction, leading to central sleep apnea, myelopathy, and sudden death.

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