Menu

6. Spine MCQs

Practice Set 253 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 5041

Topic: 6. Spine

A 60-year-old male undergoes a multi-level posterior cervical laminectomy and instrumented fusion (C3-C7) for severe cervical spondylotic myelopathy. On postoperative day 2, he is noted to have new profound weakness in right shoulder abduction and external rotation (strength 1/5). His grip strength, wrist extension, and lower extremity strength remain intact. What is the most likely etiology of this new deficit?

. Unrecognized intraoperative spinal cord injury
. C5 nerve root tethering due to spinal cord drift
. Epidural hematoma compressing the cervical cord
. Iatrogenic vertebral artery injury
. Ischemic stroke of the middle cerebral artery

Correct Answer & Explanation

. C5 nerve root tethering due to spinal cord drift

Explanation

C5 nerve root palsy is a known complication following cervical decompression surgery, particularly extensive posterior laminectomies. It typically presents as deltoid and/or biceps weakness 24 to 48 hours postoperatively, without worsening of myelopathic symptoms or long-tract signs. The widely accepted etiology is the traction or tethering effect on the relatively short and horizontal C5 nerve root as the spinal cord shifts posteriorly following decompression.

Question 5042

Topic: Thoracolumbar Spine & Deformity

A 15-year-old boy is brought by his parents for evaluation of a 'hunchback' posture. He reports mild achy pain in the mid-back after playing sports. Standing lateral radiographs demonstrate a thoracic kyphosis of 65 degrees. According to Sorensen's criteria, which of the following radiographic findings is required to confirm the diagnosis of Scheuermann's disease?

. Anterior wedging of at least 5 degrees in three or more sequential vertebrae
. A Cobb angle of greater than 45 degrees with normal vertebral morphology
. Defect in the pars interarticularis at L5
. Lateral curvature of the spine greater than 10 degrees
. Spondylolisthesis of L4 on L5

Correct Answer & Explanation

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

Explanation

Sorensen's criteria define classic Scheuermann's disease radiographically as a structural thoracic kyphosis > 40 degrees with anterior wedging of at least 5 degrees in 3 or more consecutive vertebral bodies. While Schmorl's nodes and irregular endplates are often present, sequential wedging is the definitive diagnostic criterion.

Question 5043

Topic: 6. Spine

A 42-year-old male presents to the emergency department with severe lower back pain and bilateral sciatica. He reports new-onset perineal numbness and difficulty initiating urination for the past 12 hours. On physical examination, he has decreased perianal sensation and decreased rectal tone.

The urinary retention seen in this syndrome is primarily due to dysfunction of which of the following nerve roots?

. T12 - L1
. L2 - L3
. L4 - L5
. S2 - S4
. Coccygeal nerve

Correct Answer & Explanation

. S2 - S4

Explanation

The patient presents with cauda equina syndrome. The parasympathetic innervation to the detrusor muscle, which is responsible for bladder contraction and emptying, originates from the S2, S3, and S4 spinal nerve roots (pelvic splanchnic nerves). Compression of these roots in the cauda equina leads to an areflexic bladder and subsequent urinary retention with overflow incontinence.

Question 5044

Topic: Cervical Spine

An 84-year-old man is brought to the emergency department after a ground-level fall. He complains of severe neck pain but denies any numbness, tingling, or weakness in his extremities. His medical history is significant for severe chronic obstructive pulmonary disease (COPD), coronary artery disease with a previous myocardial infarction, and poorly controlled diabetes mellitus. Neurological examination is completely intact. A CT scan of the cervical spine reveals a Type II odontoid fracture with 2 mm of posterior displacement. What is the most appropriate management for this patient?

. Halo vest immobilization
. Rigid cervical collar
. Anterior odontoid screw fixation
. Posterior C1-C2 instrumented fusion
. Transoral odontoidectomy

Correct Answer & Explanation

. Rigid cervical collar

Explanation

In octogenarians with significant medical comorbidities, non-operative management with a rigid cervical collar is favored for isolated, minimally displaced Type II odontoid fractures. Halo vest immobilization carries an unacceptably high morbidity and mortality rate in the elderly (up to 20-40%) due to restrictive respiratory mechanics, pin site infections, and increased fall risk. Operative intervention (anterior screw or posterior fusion) also carries a high perioperative risk in patients with severe cardiopulmonary disease. While the non-union rate of Type II fractures treated with a collar is high, the vast majority of these patients develop a stable fibrous non-union that is clinically asymptomatic and does not compromise neurological function or longevity.

Question 5045

Topic: 6. Spine

A 62-year-old man presents with progressive hand clumsiness, difficulty walking, and frequent tripping over the past 8 months. Physical examination demonstrates hyperreflexia in the bilateral lower extremities, a positive Hoffmann sign bilaterally, and an inverted brachioradialis reflex. Imaging shows multi-level cervical spondylosis from C3 to C6. A sagittal MRI reveals severe spinal cord compression from large anterior diskosteophyte complexes. Standing lateral radiographs demonstrate a rigid 15-degree kyphotic deformity of the cervical spine from C3 to C6. Which of the following surgical approaches is most appropriate?

. Posterior laminectomy without fusion
. Posterior laminoplasty
. Posterior laminectomy and instrumented fusion
. Anterior multi-level decompression and fusion
. Combined single-stage posterior and anterior decompression

Correct Answer & Explanation

. Anterior multi-level decompression and fusion

Explanation

In the setting of cervical spondylotic myelopathy (CSM) accompanied by a rigid kyphotic deformity, an anterior approach (such as multi-level ACDF or corpectomy) is indicated. Posterior decompression alone (laminectomy or laminoplasty) is strictly contraindicated in a rigid kyphotic spine because the spinal cord will remain draped over the anterior compressive pathology (loss of the 'bowstring' effect). Therefore, the cord will not translate posteriorly, and the neural decompression will be inadequate. Furthermore, laminectomy without fusion in this setting would further destabilize the spine and exacerbate the kyphotic deformity. An anterior approach directly addresses the anterior compressive pathology while allowing for the correction of sagittal alignment.

Question 5046

Topic: 6. Spine

A 65-year-old woman is being evaluated for progressive low back pain and an inability to stand up straight, which severely limits her daily activities. Standing full-length lateral spinopelvic radiographs are obtained to plan a multi-level corrective spinal fusion. Measurement of her spinopelvic parameters demonstrates a pelvic incidence (PI) of 60 degrees. To achieve optimal sagittal balance postoperatively and minimize the risk of adjacent segment disease, what is the ideal target for her lumbar lordosis (LL)?

. 30 degrees
. 45 degrees
. 60 degrees
. 75 degrees
. 90 degrees

Correct Answer & Explanation

. 60 degrees

Explanation

In adult spinal deformity correction, the target lumbar lordosis (LL) should match the patient's fixed pelvic incidence (PI) within 9 to 10 degrees (Formula: LL = PI ± 9°). Since this patient's PI is 60 degrees, the ideal target LL is approximately 60 degrees. Failing to restore this relationship (resulting in a PI-LL mismatch > 10°) is a primary driver of postoperative flatback syndrome, global sagittal imbalance, poor patient-reported outcome measures, and a significantly increased risk of mechanical failure or adjacent segment disease.

Question 5047

Topic: Cervical Spine

A 45-year-old man undergoes an anterior cervical discectomy and fusion (ACDF) at C5-C6 through a right-sided, transverse cervical approach. On postoperative day 1, he is noted to have severe hoarseness and coughing when attempting to drink thin liquids. Laryngoscopy confirms unilateral vocal cord paralysis. The injured structure responsible for this complication typically courses in which of the following anatomic locations?

. Superficial to the platysma
. Within the tracheoesophageal groove
. Between the prevertebral fascia and longus colli
. Lateral to the carotid sheath
. Through the substance of the thyroid gland

Correct Answer & Explanation

. Within the tracheoesophageal groove

Explanation

The patient is experiencing postoperative hoarseness and aspiration, indicative of a recurrent laryngeal nerve (RLN) injury. This is a well-known complication of anterior cervical spine surgery. As the RLN ascends into the neck to innervate the intrinsic muscles of the larynx (except the cricothyroid), it runs superiorly within the tracheoesophageal groove. The right RLN has a more variable and oblique course than the left as it loops around the right subclavian artery, which historically led to concerns that a right-sided surgical approach carried a higher risk of RLN injury, particularly at lower cervical levels.

Question 5048

Topic: 6. Spine

A 55-year-old woman undergoes a posterior C3-C7 laminectomy and instrumented fusion for severe cervical spondylotic myelopathy. Postoperatively, she awakens with improved bilateral lower extremity function and intact sensation globally. However, on postoperative day 3, she develops acute, isolated right-sided weakness in shoulder abduction and elbow flexion (Medical Research Council grade 2/5). Sensation in the upper extremities remains intact. What is the most appropriate next step in management?

. Immediate return to the operating room for hematoma evacuation
. Administration of high-dose intravenous methylprednisolone
. Observation and physical therapy
. Emergent anterior cervical discectomy at C4-C5
. Closed reduction and rigid cervical orthosis

Correct Answer & Explanation

. Observation and physical therapy

Explanation

This patient has developed a delayed C5 palsy, a well-documented complication occurring in roughly 5-10% of patients following extensive posterior cervical decompression (laminectomy or laminoplasty). It typically presents 2 to 5 days postoperatively as isolated unilateral or bilateral deltoid and biceps weakness without accompanying sensory deficits or long-tract deterioration. The exact etiology is debated but is largely attributed to the posterior drift of the spinal cord resulting in a tethering effect or traction neuropraxia on the short, horizontally oriented C5 nerve roots. Because the prognosis for spontaneous recovery is generally favorable (resolving over weeks to months in the majority of cases), the standard initial management is observation and physical therapy to maintain joint mobility. Emergent re-exploration is not indicated without signs of compressive epidural hematoma (which would typically present with severe pain, sensory loss, and long-tract signs).

Question 5049

Topic: 6. Spine

A 24-year-old motorcyclist sustains a severe traction injury to his left brachial plexus. He has a flail, completely insensate left arm. Physical examination also reveals ipsilateral ptosis, miosis, and anhidrosis. The presence of these specific facial and ocular findings most strongly indicates which of the following injury patterns?

. Post-ganglionic injury of the upper trunk
. Pre-ganglionic avulsion of the C8 and T1 nerve roots
. Post-ganglionic rupture of the middle trunk
. Pre-ganglionic avulsion of the C5 and C6 nerve roots
. Compression of the lower trunk at the thoracic outlet

Correct Answer & Explanation

. Pre-ganglionic avulsion of the C8 and T1 nerve roots

Explanation

The patient is exhibiting Horner's syndrome (ptosis, miosis, anhidrosis), which in the context of a brachial plexus injury signifies damage to the sympathetic chain. The sympathetic fibers to the head and neck exit the spinal cord at T1 and travel near the C8 and T1 nerve roots before joining the sympathetic chain. Horner's syndrome indicates a pre-ganglionic injury (root avulsion) of the lower plexus roots (C8, T1), suggesting a poor prognosis for spontaneous recovery and precluding the use of those roots as donors for nerve transfers.

Question 5050

Topic: 6. Spine

A 22-year-old motorcyclist sustains a traumatic brachial plexus injury following a high-speed collision. He presents with a completely flail and insensate right upper extremity. Physical examination reveals right-sided ptosis, miosis, and anhidrosis. What does this constellation of signs definitively indicate regarding his nerve injury?

. Upper trunk (C5-C6) preganglionic avulsion
. Upper trunk (C5-C6) postganglionic rupture
. Lower root (C8-T1) preganglionic avulsion
. Lower root (C8-T1) postganglionic rupture
. Posterior cord postganglionic rupture

Correct Answer & Explanation

. Lower root (C8-T1) preganglionic avulsion

Explanation

Ptosis, miosis, and anhidrosis describe Horner's syndrome, which indicates disruption of the sympathetic chain. In the context of a severe brachial plexus injury, this suggests a preganglionic nerve root avulsion of the lower roots (C8 and T1), as the sympathetic fibers exit the spinal cord at T1. A preganglionic avulsion represents a proximal injury that cannot be directly repaired or grafted, indicating a poor prognosis for spontaneous recovery of hand function.

Question 5051

Topic: 6. Spine

A 28-year-old motorcyclist is involved in a high-speed collision and sustains a severe traction injury to his right upper extremity. On examination, he has a flail, insensate right arm. He also exhibits right-sided ptosis, miosis, and anhidrosis. The presence of these ocular and facial symptoms strongly suggests an injury at which of the following levels?

. Postganglionic C5-C6 roots
. Preganglionic C8-T1 roots
. Postganglionic C8-T1 roots
. Upper trunk
. Posterior cord

Correct Answer & Explanation

. Preganglionic C8-T1 roots

Explanation

The patient has Horner's syndrome (ptosis, miosis, anhidrosis), which indicates disruption of the sympathetic chain. The sympathetic fibers to the head and neck exit the spinal cord at T1. Therefore, Horner's syndrome in the setting of a brachial plexus injury strongly points to a preganglionic avulsion of the lower roots (C8-T1). Preganglionic injuries have a poor prognosis for spontaneous recovery and are generally not amenable to direct nerve repair or grafting.

Question 5052

Topic: 6. Spine

A 25-year-old male is involved in a high-speed motorcycle accident and sustains a severe traction injury to his right brachial plexus. On physical examination, he has flaccid paralysis of the right upper extremity, associated with right-sided ptosis, miosis, and anhidrosis. The presence of Horner's syndrome suggests an injury at which of the following anatomic levels?

. Upper trunk (C5-C6)
. Middle trunk (C7)
. Lower trunk (C8-T1)
. Lateral cord
. Posterior cord

Correct Answer & Explanation

. Lower trunk (C8-T1)

Explanation

Horner's syndrome (ptosis, miosis, anhidrosis) in the setting of a brachial plexus injury strongly suggests avulsion of the T1 nerve root. The preganglionic sympathetic fibers to the head and neck exit the spinal cord at the T1 level and travel with the T1 nerve root before joining the sympathetic chain. Injury to the lower trunk or avulsion of the T1 root disrupts these sympathetic fibers, indicating a preganglionic injury with a poor prognosis for spontaneous recovery.

Question 5053

Topic: Cervical Spine

A 22-year-old collegiate baseball pitcher reports medial elbow pain during the late cocking and early acceleration phases of throwing. MRI confirms a partial-thickness tear of the medial ulnar collateral ligament (MUCL). Which bundle of the MUCL is the primary restraint to valgus stress at the elbow during these specific phases of the throwing motion?

. Posterior bundle
. Transverse ligament
. Anterior band of the anterior bundle
. Posterior band of the anterior bundle
. Radial collateral ligament

Correct Answer & Explanation

. Anterior band of the anterior bundle

Explanation

The medial ulnar collateral ligament (MUCL) complex is composed of the anterior, posterior, and transverse bundles. The anterior bundle is the primary restraint to valgus stress from 30 to 120 degrees of elbow flexion. The anterior bundle itself is functionally divided into anterior and posterior bands. The anterior band is the most important restraint to valgus stress and is taut in extension and early flexion, which corresponds to the extreme valgus stress encountered during the late cocking and early acceleration phases of throwing.

Question 5054

Topic: 6. Spine
A 35-year-old man presents with severe axial back pain and radiculopathy. An MRI confirms a herniated nucleus pulposus at L4-L5. Which type of collagen predominates in the normal adult nucleus pulposus, making it biomechanically suited to resist compressive loads?
. Type I
. Type II
. Type III
. Type IX
. Type X

Correct Answer & Explanation

. Type II

Explanation

The intervertebral disc is composed of the outer annulus fibrosus and the inner nucleus pulposus. The normal adult nucleus pulposus is rich in proteoglycans (predominantly aggrecan) and Type II collagen, which gives it the ability to resist high compressive loads by maintaining a high water content. In contrast, the annulus fibrosus, which resists tensile forces, is predominantly composed of Type I collagen. Type X collagen is classically found in the hypertrophic zone of the physis.

Question 5055

Topic: 6. Spine

In the lumbar spine, a surgeon is placing pedicle screws at the L4 level. If the screw inadvertently breaches the medial and inferior cortex of the L4 pedicle, which exiting nerve root is at the greatest risk of injury?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L4

Explanation

In the lumbar spine, the exiting nerve root travels just inferomedial to the pedicle of the same numerical designation. Therefore, an inferomedial breach of the L4 pedicle endangers the L4 nerve root.

Question 5056

Topic: 6. Spine

During a posterior approach to the upper cervical spine, dissecting too far laterally in the suboccipital triangle risks injuring the vertebral artery. Which structures form the borders of the suboccipital triangle?

. Rectus capitis posterior major, Obliquus capitis superior, Obliquus capitis inferior
. Rectus capitis posterior minor, Obliquus capitis superior, Splenius capitis
. Semispinalis capitis, Longissimus capitis, Trapezius
. Rectus capitis posterior major, Rectus capitis posterior minor, Obliquus capitis inferior
. Sternocleidomastoid, Trapezius, Occipital bone

Correct Answer & Explanation

. Rectus capitis posterior major, Obliquus capitis superior, Obliquus capitis inferior

Explanation

The suboccipital triangle is bordered by the rectus capitis posterior major (superomedial), obliquus capitis superior (superolateral), and obliquus capitis inferior (inferolateral). The vertebral artery and suboccipital nerve lie within this triangle.

Question 5057

Topic: 6. Spine

A 45-year-old male presents with severe right leg pain. MRI reveals a far lateral (extraforaminal) disc herniation at the L4-L5 level. Which nerve root is most likely compressed by this specific herniation?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L4

Explanation

In the lumbar spine, a far lateral (extraforaminal) disc herniation compresses the exiting nerve root at the same level. Therefore, an L4-L5 far lateral herniation impinges the L4 nerve root.

Question 5058

Topic: 6. Spine

When performing an anterior approach to the lower cervical spine (e.g., C5-C6), the recurrent laryngeal nerve is at risk. Which of the following statements correctly describes its anatomy?

. The right recurrent laryngeal nerve loops under the arch of the aorta.
. The left recurrent laryngeal nerve loops under the right subclavian artery.
. The right recurrent laryngeal nerve has a more variable, oblique course, making it more vulnerable during a right-sided approach.
. Both nerves travel in the tracheoesophageal groove but the right is protected by the carotid sheath.
. The left nerve is at higher risk of injury during a standard left-sided approach.

Correct Answer & Explanation

. The right recurrent laryngeal nerve has a more variable, oblique course, making it more vulnerable during a right-sided approach.

Explanation

The right recurrent laryngeal nerve loops under the right subclavian artery and ascends in a variable, oblique path toward the tracheoesophageal groove. Because of this variability, it is generally considered at higher risk of iatrogenic injury during right-sided cervical approaches.

Question 5059

Topic: 6. Spine

During the placement of pedicle screws at L4, the surgeon breaches the inferior cortex of the L4 pedicle. Which neural structure is at the greatest risk of direct mechanical injury?

. L3 exiting nerve root
. L4 exiting nerve root
. L5 exiting nerve root
. L4 traversing nerve root
. L5 traversing nerve root

Correct Answer & Explanation

. L4 exiting nerve root

Explanation

In the lumbar spine, the exiting nerve root travels immediately inferior to the pedicle of the same number. Therefore, an inferior breach of the L4 pedicle directly endangers the L4 exiting nerve root.

Question 5060

Topic: Cervical Spine

During an anterior cervical discectomy and fusion (ACDF), excessive lateral bone removal using a burr puts the vertebral artery at significant risk. The vertebral artery typically enters the transverse foramen first at which cervical level?

. C7
. C6
. C5
. C4
. C3

Correct Answer & Explanation

. C6

Explanation

The vertebral artery typically enters the transverse foramen at C6 in over 90% of individuals. Dissection too far laterally during lower cervical exposures places it at high risk.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page