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6. Spine MCQs

Practice Set 325 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 6481

Topic: 6. Spine

A 35-year-old recent immigrant presents with progressive thoracic back pain, fevers, and an increasing kyphotic deformity. Imaging demonstrates destruction of the T8 and T9 vertebral bodies with large paraspinal fluid collections. Which of the following findings is more characteristic of spinal tuberculosis (Pott's disease) compared to pyogenic spondylodiscitis?

. Rapid clinical progression over days
. Preferential and rapid early destruction of the intervertebral disc
. Relative sparing of the intervertebral discs until late in the disease process
. Predilection for the posterior elements rather than the vertebral bodies
. Profoundly elevated serum leukocyte count commonly exceeding 30,000/uL

Correct Answer & Explanation

. Relative sparing of the intervertebral discs until late in the disease process

Explanation

Mycobacterium tuberculosis infection of the spine (Pott's disease) primarily affects the anterior portion of the vertebral bodies. The infection tends to spread beneath the anterior longitudinal ligament to adjacent vertebrae. Unlike pyogenic infections, which rapidly destroy cartilage and the intervertebral disc through proteolytic enzymes, M. tuberculosis lacks these enzymes, leading to characteristically late sparing of the intervertebral disc spaces.

Question 6482

Topic: 6. Spine

A 70-year-old male with a history of cervical spondylosis falls forward, striking his chin. He develops severe weakness in his upper extremities, but is relatively able to walk. The disproportionate weakness in the upper extremities compared to the lower extremities is due to the anatomical arrangement of which specific spinal cord tract?

. Anterior spinothalamic tract
. Dorsal column medial lemniscus
. Lateral corticospinal tract
. Vestibulospinal tract
. Rubrospinal tract

Correct Answer & Explanation

. Lateral corticospinal tract

Explanation

This patient has Central Cord Syndrome. The disproportionate weakness in the upper extremities occurs because the motor fibers innervating the cervical region (arms/hands) are located more centrally/medially within the lateral corticospinal tract. Fibers innervating the trunk, legs, and sacral region are layered progressively more peripherally (laterally), sparing them in central cord injuries.

Question 6483

Topic: 6. Spine

A 50-year-old female presents with severe neck pain radiating down her lateral forearm and into her thumb. On physical examination, she demonstrates 4/5 strength in wrist extension and elbow flexion. Which of her deep tendon reflexes is most likely to be diminished?

. Triceps reflex
. Brachioradialis reflex
. Pectoralis reflex
. Hoffmann's reflex
. Finger flexor reflex

Correct Answer & Explanation

. Brachioradialis reflex

Explanation

The patient's clinical presentation is classic for a C6 radiculopathy. C6 compression causes sensory changes in the lateral forearm and thumb (C6 dermatome), weakness in wrist extension (extensor carpi radialis longus/brevis) and elbow flexion (biceps/brachialis), and a diminished or absent brachioradialis reflex. A diminished triceps reflex would point to C7.

Question 6484

Topic: 6. Spine
A 25-year-old male is evaluated following a crushing pelvic injury. CT imaging reveals a vertical fracture of the sacrum that extends through the central sacral canal. According to the Denis classification of sacral fractures, this is a Zone III injury. Which of the following clinical deficits is most highly associated with this specific injury zone?
. Isolated L5 radiculopathy
. Isolated S1 radiculopathy
. Bowel, bladder, and sexual dysfunction
. Ipsilateral quadriceps weakness
. Loss of proprioception in the lower limbs

Correct Answer & Explanation

. Bowel, bladder, and sexual dysfunction

Explanation

The Denis classification of sacral fractures divides them into three zones based on their relationship to the sacral foramina. Zone I (alar) is lateral to the foramina. Zone II (foraminal) involves the foramina and frequently causes sciatica/radiculopathy. Zone III (central canal) involves the central sacral spinal canal and carries the highest rate of neurologic injury (up to 57%), characteristically presenting as cauda equina syndrome with bowel, bladder, and sexual dysfunction.

Question 6485

Topic: 6. Spine

An orthopedic resident is applying a halo vest to an adult patient with a high cervical spine fracture. To ensure safe placement of the anterior pins, what is the appropriate anatomical location and application torque to minimize the risk of neurovascular injury and pin failure?

. Medial to the supraorbital notch at 8 in-lb
. Lateral to the supraorbital notch at 8 in-lb
. Medial to the supraorbital notch at 2 in-lb
. Lateral to the supraorbital notch at 2 in-lb
. Directly within the temporalis muscle at 8 in-lb

Correct Answer & Explanation

. Lateral to the supraorbital notch at 8 in-lb

Explanation

The anterior "safe zone" for halo pin placement is approximately 1 cm superior to the orbital rim, centered over the lateral two-thirds of the orbit (lateral to the supraorbital notch). Placing the pins medial to this notch risks injuring the supraorbital and supratrochlear nerves. The standard application torque for a rigid halo in adults is 8 in-lb. In pediatric patients, multiple pins and a lower torque (e.g., 2-4 in-lb) are used depending on bone age.

Question 6486

Topic: 6. Spine

A 65-year-old male with long-standing ankylosing spondylitis presents to the emergency department after a mechanical ground-level fall. He complains of severe lower neck pain. Neurological examination is intact. Lateral cervical spine radiographs show no obvious fracture. What is the most appropriate next step in management?

. Discharge with a soft cervical collar and outpatient follow-up
. Perform flexion-extension cervical radiographs to assess for instability
. Obtain a non-contrast CT scan of the cervical spine
. Obtain an MRI of the cervical spine with and without contrast
. Administer high-dose methylprednisolone

Correct Answer & Explanation

. Obtain a non-contrast CT scan of the cervical spine

Explanation

Patients with ankylosing spondylitis (AS) have a highly rigid, osteopenic spine that acts like a long bone, making it highly susceptible to fractures even from low-energy trauma (e.g., ground-level falls). The cervicothoracic junction is the most common site. Plain radiographs often miss these fractures due to altered anatomy, osteopenia, and superimposed shoulder shadows. A non-contrast CT scan is the gold standard and strictly required in any AS patient with neck/back pain following trauma, regardless of normal initial plain films. Flexion-extension views are contraindicated due to the risk of iatrogenic spinal cord injury.

Question 6487

Topic: 6. Spine

Which of the following is a strict diagnostic criterion for Diffuse Idiopathic Skeletal Hyperostosis (DISH) according to Resnick and Niwayama?

. Presence of flowing anterior ossification over at least four contiguous vertebral bodies
. Complete obliteration and fusion of both sacroiliac joints
. Severe intervertebral disc height loss and vacuum disc phenomenon
. Positive HLA-B27 antigen test
. Marginal syndesmophytes predominantly affecting the lumbar spine

Correct Answer & Explanation

. Presence of flowing anterior ossification over at least four contiguous vertebral bodies

Explanation

The Resnick and Niwayama criteria for DISH include: 1) Flowing ossification along the anterolateral aspect of at least four contiguous vertebral bodies. 2) Relative preservation of intervertebral disc height in the involved segments and absence of extensive radiographic changes of degenerative disc disease (no vacuum phenomenon or marginal sclerosis). 3) Absence of apophyseal joint bony ankylosis and sacroiliac joint erosion, sclerosis, or intra-articular osseous fusion (which critically distinguishes it from Ankylosing Spondylitis). DISH is not associated with HLA-B27.

Question 6488

Topic: Cervical Spine
An 8-year-old girl presents with painful torticollis one week after recovering from an upper respiratory tract infection. Radiographs demonstrate an atlantoaxial rotatory subluxation. According to the Fielding and Hawkins classification, a Type II injury is characterized by:
. Rotatory displacement with an intact transverse ligament and no anterior displacement
. Rotatory displacement with an anterior displacement of 3 to 5 mm, indicating transverse ligament deficiency
. Rotatory displacement with an anterior displacement greater than 5 mm, indicating bilateral alar ligament deficiency
. Posterior rotatory displacement of the atlas on the axis
. Rotatory displacement combined with a vertical subluxation of the odontoid

Correct Answer & Explanation

. Rotatory displacement with an anterior displacement of 3 to 5 mm, indicating transverse ligament deficiency

Explanation

Fielding and Hawkins classified atlantoaxial rotatory subluxation (AARS) into four types. Type I: Rotatory fixation with no anterior displacement (ADI < 3 mm); transverse ligament intact. Type II: Rotatory fixation with anterior displacement of 3 to 5 mm; indicates transverse ligament deficiency. Type III: Rotatory fixation with anterior displacement > 5 mm; indicates deficiency of both the transverse and alar ligaments. Type IV: Posterior rotatory fixation. The scenario describes Grisel's syndrome (AARS secondary to head/neck infection/inflammation).

Question 6489

Topic: Thoracolumbar Spine & Deformity

A 30-year-old male sustains a T12 burst fracture after a fall. On examination, he is neurologically intact. MRI demonstrates definitive disruption of the posterior ligamentous complex (PLC). According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is his total score and the recommended management?

. Score 2; Non-operative management
. Score 4; Surgeon's choice of operative or non-operative management
. Score 5; Operative management
. Score 7; Operative management
. Score 8; Non-operative management

Correct Answer & Explanation

. Score 5; Operative management

Explanation

The TLICS system evaluates three categories: morphology, neurologic status, and posterior ligamentous complex (PLC) integrity. This patient has a burst fracture morphology (2 points), intact neurologic status (0 points), and a definitively disrupted PLC (3 points). Total score = 2 + 0 + 3 = 5. A TLICS score <= 3 suggests non-operative management, a score of 4 is indeterminate (surgeon's choice), and a score >= 5 is a strong indication for surgical management.

Question 6490

Topic: 6. Spine

A 68-year-old man presents to the emergency department after a hyperextension injury to his neck during a motor vehicle collision. He exhibits severe motor weakness in his hands and arms, with relatively preserved strength in his legs. Perianal sensation and sphincter tone are intact. Which of the following anatomical structures is primarily damaged in this syndrome?

. Dorsal columns
. Spinothalamic tracts
. Central gray matter and medial aspect of the corticospinal tracts
. Anterior horn cells only
. Peripheral nerve roots at the level of the injury

Correct Answer & Explanation

. Central gray matter and medial aspect of the corticospinal tracts

Explanation

The patient is presenting with Central Cord Syndrome, the most common incomplete spinal cord injury, typically occurring in elderly patients with pre-existing cervical spondylosis who sustain a hyperextension injury. The pathognomonic finding is disproportionately greater motor impairment in the upper extremities compared to the lower extremities. The pathophysiology involves injury to the central gray matter and the medial aspect of the lateral corticospinal tracts (which carry motor fibers for the cervical segments/upper extremities, whereas lumbar/sacral fibers are located more laterally).

Question 6491

Topic: 6. Spine

A 45-year-old intravenous drug user presents with a two-week history of worsening back pain, fever, and new-onset urinary retention. MRI of the lumbar spine confirms a ventral epidural abscess at L3-L4 compressing the cauda equina. Which of the following dictates the urgent need for surgical decompression rather than isolated medical management?

. The ventral location of the abscess
. The size of the abscess on MRI
. The patient's history of intravenous drug use
. The presence of new-onset urinary retention
. Elevated CRP and ESR levels

Correct Answer & Explanation

. The presence of new-onset urinary retention

Explanation

Spinal epidural abscesses can often be managed with culture-directed antibiotics alone if the patient is neurologically intact. However, the development of a neurological deficit (such as urinary retention, indicating cauda equina syndrome, or progressing motor weakness) is an absolute indication for urgent surgical decompression to prevent irreversible neurological damage. Factors like location (ventral vs dorsal), inflammatory marker levels, and etiology guide the broader treatment plan but do not single-handedly dictate the need for emergent surgery over neurological status.

Question 6492

Topic: 6. Spine

A 15-year-old boy presents with progressive thoracic curvature and mid-back pain. Radiographs reveal a severe thoracic kyphosis. According to Sorensen's criteria, a definitive diagnosis of Scheuermann's kyphosis requires which of the following radiographic findings?

. Anterior wedging of at least 5 degrees in one or more contiguous vertebrae
. Anterior wedging of at least 5 degrees in three or more contiguous vertebrae
. Schmorl's nodes in at least three contiguous vertebrae
. Global thoracic kyphosis greater than 60 degrees
. Loss of anterior disc height at the apex of the kyphosis

Correct Answer & Explanation

. Anterior wedging of at least 5 degrees in three or more contiguous vertebrae

Explanation

Scheuermann's kyphosis is a structural deformity of the thoracic or thoracolumbar spine occurring during adolescence. According to Sorensen's criteria, the diagnosis is radiographically confirmed by the presence of anterior wedging of at least 5 degrees in three or more contiguous vertebral bodies. Other associated but non-diagnostic findings include Schmorl's nodes, endplate irregularities, and intervertebral disc space narrowing.

Question 6493

Topic: Thoracolumbar Spine & Deformity
A 14-year-old female presents with severe mechanical lower back pain and a 'waddling' gait. Radiographs reveal a Meyerding Grade IV isthmic spondylolisthesis at L5-S1. The slip angle is measured at 55 degrees. What is the most critical pelvic parameter that determines the overall sagittal balance and risk of progression in this patient?
. Sacral Slope
. Pelvic Tilt
. Pelvic Incidence
. Lumbar Lordosis
. Sagittal Vertical Axis

Correct Answer & Explanation

. Pelvic Incidence

Explanation

Pelvic Incidence (PI) is a fixed morphological parameter unique to each individual and is defined as the sum of Pelvic Tilt (PT) and Sacral Slope (SS) (PI = PT + SS). In high-grade spondylolisthesis (Meyerding Grade III-V), patients typically have a high Pelvic Incidence, which predisposes them to greater shear forces at the lumbosacral junction. A high slip angle (>45-50 degrees) combined with high PI strongly correlates with an increased risk of further progression and poor functional outcomes, often necessitating surgical reduction and stabilization.

Question 6494

Topic: 6. Spine

A 25-year-old male sustains a gunshot wound to the abdomen. The bullet traversed the descending colon and lodged in the L3 vertebral body. The patient has 4/5 weakness in right hip flexion and knee extension. The abdomen is explored, and a bowel repair is performed. Regarding the spinal injury, what is the most appropriate management?

. Immediate surgical extraction of the bullet via a posterior laminectomy
. Immediate anterior corpectomy and bullet extraction
. Administration of broad-spectrum antibiotics for 7-14 days and observation of the spine
. Administration of intravenous methylprednisolone for 48 hours
. Observation with no antibiotic therapy required

Correct Answer & Explanation

. Administration of broad-spectrum antibiotics for 7-14 days and observation of the spine

Explanation

In the management of spinal gunshot wounds, routine bullet removal is generally not indicated unless the bullet is within the spinal canal causing a progressive neurologic deficit, or if it is located within the thecal sac. In cases where a bullet traverses a hollow viscus (e.g., colon) before lodging in the spine, the primary treatment is broad-spectrum intravenous antibiotics (covering anaerobes and gram-negatives for 7-14 days) to prevent osteomyelitis/discitis. Stable or non-progressive incomplete deficits are usually observed. Steroids are contraindicated in penetrating spinal cord injuries.

Question 6495

Topic: 6. Spine

A 60-year-old Asian male presents with progressive clumsiness in his hands and a wide-based gait. CT of the cervical spine shows severe Ossification of the Posterior Longitudinal Ligament (OPLL) from C3 to C6, occupying 60% of the spinal canal. The 'double-layer sign' is present on the axial CT. What does this sign indicate?

. Concomitant ossification of the anterior longitudinal ligament
. Presence of a herniated nucleus pulposus behind the OPLL mass
. Dural ossification and a high risk of cerebrospinal fluid (CSF) leak during anterior resection
. Severe myelomalacia of the spinal cord
. An unstable cervical spine requiring immediate halo fixation

Correct Answer & Explanation

. Dural ossification and a high risk of cerebrospinal fluid (CSF) leak during anterior resection

Explanation

The 'double-layer sign' on a CT scan in a patient with OPLL represents a hyperdense ossified PLL and a hyperdense ossified dura mater separated by a hypodense central layer. This radiographic finding is highly specific for dural ossification. Surgeons must be aware of this, as attempting an anterior resection of the OPLL mass carries a very high risk of dural tearing and subsequent CSF leak. In such cases, posterior decompression or a modified anterior approach (leaving the ossified dura/OPLL 'floating') is typically preferred.

Question 6496

Topic: 6. Spine

A 58-year-old woman with a history of breast cancer presents with mechanical back pain localized to T8. She is neurologically intact. According to the Spinal Instability Neoplastic Score (SINS), which of the following clinical or radiographic features contributes the maximum number of points toward the total score?

. Posterolateral location of the lesion
. Blastic nature of the bone lesion
. Pain improvement with recumbency (mechanical pain)
. Involvement of the T8 vertebral level
. Intact posterior elements

Correct Answer & Explanation

. Pain improvement with recumbency (mechanical pain)

Explanation

The Spinal Instability Neoplastic Score (SINS) is used to assess spinal stability in neoplastic disease. Severe mechanical pain (pain with movement/loading, relieved by recumbency) is a hallmark of instability and scores the maximum 3 points in the pain category. T8 is considered a semi-rigid location (1 point). Blastic lesions imply stability and score 0 points. Mechanical pain heavily influences the decision for surgical stabilization.

Question 6497

Topic: 6. Spine

A 35-year-old male arrives at the trauma bay comatose (GCS 6) following a high-speed motorcycle crash. Lateral cervical spine radiographs show a C5-C6 bilateral facet dislocation with 50% anterior translation of C5 on C6. What is the most appropriate next step in the management of his cervical spine injury?

. Immediate awake closed traction reduction using Gardner-Wells tongs
. Emergent MRI of the cervical spine prior to any reduction attempt
. Immediate operative anterior cervical discectomy and fusion (ACDF)
. Application of a halo vest and observation until the patient regains consciousness
. Immediate posterior cervical open reduction and fusion

Correct Answer & Explanation

. Emergent MRI of the cervical spine prior to any reduction attempt

Explanation

In a patient with a cervical facet dislocation, closed reduction via cranial traction can be performed safely in an awake, alert, and cooperative patient who can provide continuous neurological feedback. However, in an obtunded or unexaminable patient (like this comatose male), closed reduction is contraindicated due to the inability to assess for neurological worsening. An emergent MRI must be obtained first to rule out a herniated disc behind the vertebral body prior to any closed or open reduction attempt.

Question 6498

Topic: Thoracolumbar Spine & Deformity
In the evaluation of adult spinal deformity, which of the following radiographic parameters has been most strongly and consistently correlated with poor Health-Related Quality of Life (HRQOL) scores?
. A coronal Cobb angle greater than 30 degrees
. A pelvic incidence to lumbar lordosis (PI-LL) mismatch of less than 10 degrees
. A Sagittal Vertical Axis (SVA) greater than 50 mm
. A thoracic kyphosis greater than 40 degrees
. An apical vertebral rotation of Grade III

Correct Answer & Explanation

. A Sagittal Vertical Axis (SVA) greater than 50 mm

Explanation

In adult spinal deformity, sagittal plane alignment is the primary driver of clinical symptoms and poor Health-Related Quality of Life (HRQOL) scores. A positive Sagittal Vertical Axis (SVA) > 50 mm (measured as the horizontal distance from a plumb line dropped from the center of the C7 vertebral body to the posterior superior corner of the S1 endplate) correlates strongly with increased pain and decreased function. While a PI-LL mismatch > 10 degrees is also a crucial predictor, the option provided incorrectly stated 'less than 10 degrees'.

Question 6499

Topic: 6. Spine

A 40-year-old male presents with severe acute low back pain radiating to both legs, saddle anesthesia, and urinary incontinence. An MRI reveals a massive central L4-L5 disc herniation. The pathophysiology of his urinary incontinence is most accurately described as:

. Detrusor sphincter dyssynergia due to upper motor neuron injury
. Overflow incontinence secondary to a flaccid, areflexic bladder
. Spastic bladder leading to urge incontinence
. Direct mechanical compression of the sympathetic chain at L2
. Loss of cortical inhibition to the pontine micturition center

Correct Answer & Explanation

. Overflow incontinence secondary to a flaccid, areflexic bladder

Explanation

Cauda Equina Syndrome (CES) represents a lower motor neuron (LMN) injury caused by compression of the lumbosacral nerve roots below the conus medullaris. The parasympathetic fibers originating from S2-S4 mediate bladder contraction. Compression of these roots leads to an areflexic, flaccid bladder (detrusor areflexia). As the bladder fills beyond its capacity without the ability to contract, the intravesical pressure overcomes sphincter resistance, resulting in overflow incontinence. Post-void residual volume (PVR) is typically elevated.

Question 6500

Topic: 6. Spine

A 72-year-old male with pre-existing cervical stenosis experiences a hyperextension injury during a fall. He presents with profound bilateral upper extremity motor weakness but is still able to ambulate with only mild lower extremity clumsiness. Proprioception and vibratory sensation are preserved. What is the primary pathophysiologic mechanism for this specific neurologic deficit?

. Ischemia isolated to the anterior spinal artery
. Bilateral disruption of the lateral spinothalamic tracts
. Central grey matter hemorrhage and edema
. Avulsion of the dorsal root ganglia
. Complete transection of the posterior columns

Correct Answer & Explanation

. Central grey matter hemorrhage and edema

Explanation

This patient presents with Central Cord Syndrome, typical of hyperextension injuries in stenotic cervical spines. The pathophysiology involves central grey matter hemorrhage and edema, which disproportionately affects the medially located cervical motor tracts compared to the peripheral sacral/lumbar tracts.

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