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6. Spine MCQs

Practice Set 347 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 6921

Topic: 6. Spine

A 65-year-old man presents with progressive clumsiness in his hands. He demonstrates the 'finger escape sign,' characterized by spontaneous abduction of the small finger when holding his hands outstretched. This physical examination finding is primarily caused by weakness of which of the following muscle groups?

. Lumbricals
. Dorsal interossei
. Palmar interossei
. Thenar muscles
. Extensor digiti minimi

Correct Answer & Explanation

. Palmar interossei

Explanation

The finger escape sign (Wartenberg's sign of myelopathy) is commonly seen in cervical spondylotic myelopathy. It results from weakness of the ulnar-innervated intrinsic muscles, specifically the palmar interossei (which adduct the fingers), allowing the intact extensor digiti minimi (radial nerve) to pull the small finger into abduction.

Question 6922

Topic: 6. Spine

A patient with severe degenerative lumbar spinal stenosis presents with classic neurogenic claudication. Which of the following activities or postural changes most characteristically alleviates this patient's symptoms?

. Extension of the lumbar spine
. Walking downhill
. Lumbar flexion, such as leaning forward on a shopping cart
. Prolonged standing in an upright posture
. Lying prone

Correct Answer & Explanation

. Lumbar flexion, such as leaning forward on a shopping cart

Explanation

Neurogenic claudication is exacerbated by lumbar extension (standing, walking downhill) which decreases the cross-sectional area of the spinal canal. It is relieved by lumbar flexion (sitting, leaning forward on a shopping cart), which opens the central canal and neural foramina.

Question 6923

Topic: 6. Spine

In a patient suffering from an acute traumatic spinal cord injury, which of the following clinical examination findings definitively marks the end of the spinal shock phase?

. Return of deep tendon reflexes in the lower extremities
. Return of the bulbocavernosus reflex
. Resolution of the neurogenic bladder requiring catheterization
. Normalization of systemic blood pressure and resting heart rate
. Return of any purposeful distal motor function

Correct Answer & Explanation

. Return of the bulbocavernosus reflex

Explanation

Spinal shock is a temporary physiologic state of flaccid paralysis, areflexia, and loss of autonomic control below the level of a spinal cord injury. The return of the bulbocavernosus reflex (a polysynaptic reflex mediated by the S2-S4 nerve roots) classically signals the end of the spinal shock phase. Accurate determination of the completeness of the spinal cord injury (ASIA grading) is only reliable after spinal shock has resolved.

Question 6924

Topic: 6. Spine

During the physical examination of a 65-year-old patient with suspected cervical spondylotic myelopathy, you elicit a positive inverted brachioradialis reflex. This highly specific localizing finding is indicative of spinal cord compression at which anatomical level?

. C3-C4
. C4-C5
. C5-C6
. C6-C7
. C7-T1

Correct Answer & Explanation

. C5-C6

Explanation

An inverted brachioradialis reflex is elicited by tapping the brachioradialis tendon at the distal radius. A positive test consists of a diminished or absent brachioradialis reflex (representing a lower motor neuron lesion at the C5-C6 level) paradoxically coupled with reflexive spastic flexion of the fingers (an upper motor neuron sign indicating spinal cord compression above the reflex arc of the finger flexors, which are C8). This classic combination specifically localizes the compressive cervical myelopathy to the C5-C6 level.

Question 6925

Topic: 6. Spine

A 25-year-old male arrives in the trauma bay following a motor vehicle collision. He has no motor or sensory function below the T4 dermatome. A digital rectal examination reveals absent rectal tone and an absent bulbocavernosus reflex. Which of the following statements regarding his neurologic status is most accurate?

. He has a complete spinal cord injury according to the ASIA classification.
. High-dose methylprednisolone administration is universally indicated within 8 hours.
. The presence of spinal shock precludes the final determination of a complete versus incomplete spinal cord injury.
. Early surgical decompression is guaranteed to reverse his motor deficits.
. The absent bulbocavernosus reflex indicates an isolated cauda equina syndrome.

Correct Answer & Explanation

. The presence of spinal shock precludes the final determination of a complete versus incomplete spinal cord injury.

Explanation

An absent bulbocavernosus reflex (BCR) signifies the presence of spinal shock. Spinal shock is a state of transient physiologic reflex depression of spinal cord function below the level of the injury. Until spinal shock resolves (marked by the return of the BCR), a clinician cannot definitively classify the spinal cord injury as complete or incomplete, because neurologic function may return once the shock phase dissipates.

Question 6926

Topic: 6. Spine

A 6-year-old child presents with a refusal to walk, bleeding gums, and petechiae. Radiographs reveal a 'Frankel line' and 'Wimberger ring sign'. The underlying pathophysiology of this condition is a defect in which of the following processes?

. Gamma-carboxylation of osteocalcin
. Hydroxylation of proline and lysine residues
. Cleavage of type I procollagen
. Cross-linking of hydroxylysine residues
. Mineralization of newly formed osteoid

Correct Answer & Explanation

. Hydroxylation of proline and lysine residues

Explanation

This clinical and radiographic presentation is classic for scurvy (Vitamin C deficiency). Vitamin C is an essential cofactor for the enzymes prolyl hydroxylase and lysyl hydroxylase. Without hydroxylation of proline and lysine, collagen chains cannot form stable triple helices or undergo proper extracellular cross-linking, resulting in fragile blood vessels, poor wound healing, and defective bone formation.

Question 6927

Topic: 6. Spine

A 22-year-old man dives into shallow water and sustains a severe cervical spine injury resulting in complete tetraplegia. In the emergency department, his vital signs show a heart rate of 50 bpm and blood pressure of 85/50 mmHg. His extremities are warm and well-perfused. Which of the following best explains this clinical picture?

. Hypovolemic shock
. Cardiogenic shock
. Spinal shock
. Neurogenic shock
. Septic shock

Correct Answer & Explanation

. Neurogenic shock

Explanation

Neurogenic shock occurs after a spinal cord injury (usually above T6) due to the loss of sympathetic tone. This results in unopposed vagal parasympathetic tone leading to bradycardia and systemic vasodilation (hypotension with warm extremities). Spinal shock refers to the temporary loss of spinal reflexes below the level of injury and is a neurological, rather than hemodynamic, phenomenon.

Question 6928

Topic: 6. Spine

A 45-year-old male complains of neck pain radiating down his right arm. Examination reveals weakness in wrist flexion and finger extension, with a diminished triceps reflex. Sensation is decreased over the dorsal aspect of the long finger. Which cervical nerve root is most likely compressed?

. C5
. C6
. C7
. C8
. T1

Correct Answer & Explanation

. C7

Explanation

A C7 radiculopathy is characterized by weakness in the triceps (elbow extension), wrist flexors, and finger extensors. The triceps reflex is typically diminished, and numbness or tingling is usually felt in the middle (long) finger.

Question 6929

Topic: 6. Spine

A 70-year-old male presents with bilateral leg pain and heaviness that worsens with walking. Which of the following historical or physical examination findings is most specific for neurogenic claudication (lumbar spinal stenosis) rather than vascular claudication?

. Pain relief upon standing still for 5 minutes
. Diminished posterior tibial pulses
. Symptoms are exacerbated by riding a stationary bicycle
. Pain relief when leaning forward on a shopping cart
. Trophic skin changes and hair loss on the lower legs

Correct Answer & Explanation

. Pain relief when leaning forward on a shopping cart

Explanation

Neurogenic claudication is posture-dependent. Spinal extension narrows the canal, exacerbating symptoms, while spinal flexion (e.g., leaning forward on a shopping cart or riding a bicycle) increases canal volume and relieves symptoms. Vascular claudication is strictly distance/exertion-dependent and is quickly relieved by simply stopping and standing still.

Question 6930

Topic: 6. Spine

A 45-year-old male presents with severe lower back pain, bilateral lower extremity weakness, and saddle anesthesia. Post-void residual (PVR) volume is 400 mL. What is the most critical next step in management?

. High-dose IV methylprednisolone
. Urgent MRI of the lumbar spine followed by surgical decompression
. Electromyography (EMG)
. Physical therapy and NSAIDs
. Epidural steroid injection

Correct Answer & Explanation

. Urgent MRI of the lumbar spine followed by surgical decompression

Explanation

The patient has signs of Cauda Equina Syndrome (saddle anesthesia, bilateral weakness, urinary retention indicated by high PVR). This is a surgical emergency requiring urgent MRI and prompt surgical decompression (typically within 24-48 hours) to maximize neurological recovery.

Question 6931

Topic: 6. Spine

A 65-year-old male presents with deteriorating handwriting and difficulty buttoning his shirts. Physical exam reveals an inverted brachioradialis reflex. This finding is most indicative of compression at which spinal level?

. C3-C4
. C4-C5
. C5-C6
. C6-C7
. C7-T1

Correct Answer & Explanation

. C5-C6

Explanation

The inverted brachioradialis reflex is a classic upper motor neuron sign seen in cervical spondylotic myelopathy. It occurs when tapping the brachioradialis tendon produces paradoxical finger flexion (a lower cervical response) rather than elbow flexion (the expected C6 response) while the C5 and C6 reflex arc is diminished. It localizes the maximal level of cord compression to the C5-C6 level.

Question 6932

Topic: 6. Spine

According to the Thoracolumbar Injury Classification and Severity Score (TLICS), which of the following injury components assigns the highest number of points (3 points) to the overall score?

. Burst fracture morphology
. Complete spinal cord injury
. Disrupted posterior ligamentous complex (PLC)
. Compression fracture morphology
. Nerve root injury

Correct Answer & Explanation

. Disrupted posterior ligamentous complex (PLC)

Explanation

In the TLICS system: Morphology (Compression = 1, Burst = 2, Translation/Rotation = 3, Distraction = 4). Neurological status (Intact = 0, Nerve root = 2, Complete cord = 2, Incomplete cord = 3, Cauda equina = 3). Posterior Ligamentous Complex (Intact = 0, Indeterminate = 2, Disrupted = 3). Therefore, a disrupted PLC contributes 3 points. A total TLICS score > 4 favors operative management; < 4 favors nonoperative; = 4 is indeterminate.

Question 6933

Topic: 6. Spine

A 35-year-old male is involved in a high-speed motor vehicle collision. Radiographs demonstrate bilateral pars interarticularis fractures of C2. What is the most common mechanism of injury for this specific fracture pattern?

. Hyperflexion and distraction
. Hyperextension and axial loading
. Axial compression alone
. Lateral bending
. Rotational shear

Correct Answer & Explanation

. Hyperextension and axial loading

Explanation

Traumatic spondylolisthesis of the axis (Hangman's fracture) is typically caused by hyperextension and axial loading. This forces the posterior elements against the C3 articular processes, fracturing the pars interarticularis of C2.

Question 6934

Topic: Cervical Spine

A 45-year-old male presents after a diving accident. Radiographs reveal a C1 burst fracture. An open mouth odontoid view demonstrates lateral displacement of the C1 lateral masses. A displacement greater than 6.9 mm indicates rupture of which of the following structures?

. Alar ligament
. Apical ligament
. Transverse ligament
. Tectorial membrane
. Ligamentum flavum

Correct Answer & Explanation

. Transverse ligament

Explanation

The Rule of Spence states that if the combined overhang of the C1 lateral masses on C2 is greater than 6.9 mm on an AP open-mouth radiograph, it implies a rupture of the transverse ligament. This indicates instability and may require surgical stabilization.

Question 6935

Topic: Thoracolumbar Spine & Deformity

A 16-year-old gymnast complains of chronic low back pain exacerbated by extension. Oblique lumbar radiographs demonstrate a "collar on the Scotty dog." What is the exact anatomical location of this defect?

. Pedicle
. Lamina
. Pars interarticularis
. Transverse process
. Spinous process

Correct Answer & Explanation

. Pars interarticularis

Explanation

The "collar on the Scotty dog" on oblique radiographs represents a defect or fracture in the pars interarticularis. This condition, known as isthmic spondylolysis, is common in adolescent athletes involved in repetitive hyperextension sports.

Question 6936

Topic: 6. Spine

A 65-year-old male complains of bilateral lower extremity pain radiating to the calves when walking. The pain is relieved by leaning forward on a shopping cart. Which of the following exam findings best differentiates neurogenic claudication from vascular claudication?

. Diminished popliteal pulses
. Pain relief with standing completely still and upright
. Preservation of symptoms during stationary cycling
. Symptom resolution when cycling with the spine flexed
. Presence of a resting tremor

Correct Answer & Explanation

. Symptom resolution when cycling with the spine flexed

Explanation

Neurogenic claudication is typically relieved by spinal flexion (e.g., leaning forward, cycling), which increases the cross-sectional area of the spinal canal. Vascular claudication causes pain with exertion regardless of spinal posture, so cycling will reproduce symptoms.

Question 6937

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with chronic low back pain. Radiographs reveal a grade I isthmic spondylolisthesis at L5-S1. The primary anatomic defect in this condition is located in the:

. Pedicle
. Pars interarticularis
. Spinous process
. Facet joint
. Vertebral body endplate

Correct Answer & Explanation

. Pars interarticularis

Explanation

Isthmic spondylolisthesis is caused by a structural defect or stress fracture in the pars interarticularis. This defect is classically visualized as a "collar on the Scotty dog" on oblique lumbar radiographs.

Question 6938

Topic: 6. Spine

A 24-year-old male sustains a severe cervical spine trauma resulting in a complete spinal cord injury at C5. In the emergency department, his blood pressure is 80/50 mmHg, heart rate is 45 bpm, and his extremities are warm and well-perfused. Which of the following is the primary pathophysiologic mechanism for his hemodynamic state?

. Loss of sympathetic vascular tone
. Loss of parasympathetic outflow
. Massive release of systemic inflammatory mediators
. Acute adrenal insufficiency
. Hemorrhage from an unrecognized solid organ injury

Correct Answer & Explanation

. Loss of sympathetic vascular tone

Explanation

This patient is exhibiting signs of neurogenic shock, characterized by hypotension, bradycardia, and warm extremities. This is caused by a loss of descending sympathetic outflow to the vasculature and heart (typically from injuries above T6), resulting in unopposed parasympathetic vagal tone and profound peripheral vasodilation.

Question 6939

Topic: 6. Spine

A 45-year-old male is evaluated following a diving accident. A CT scan of the cervical spine reveals a four-part burst fracture of the C1 ring (Jefferson fracture). Which of the following radiographic parameters on an open-mouth odontoid view is most indicative of a complete transverse atlantal ligament rupture, indicating instability?

. Combined lateral mass displacement > 6.9 mm
. Atlantodental interval > 3 mm
. Basion-dental interval > 12 mm
. Prevertebral soft tissue swelling > 10 mm
. A C1-C2 spinous process distance > 2 cm

Correct Answer & Explanation

. Combined lateral mass displacement > 6.9 mm

Explanation

According to the Rule of Spence, an open-mouth odontoid radiograph showing a combined displacement of the lateral masses of C1 relative to the lateral borders of the C2 superior articular facets greater than 6.9 mm strongly suggests rupture of the transverse atlantal ligament, rendering the fracture highly unstable.

Question 6940

Topic: 6. Spine

A 25-year-old male presents following a severe motor vehicle collision with bilateral lower extremity paralysis. His heart rate is 55 bpm and blood pressure is 80/50 mmHg. What is the most reliable clinical indicator that the patient has emerged from spinal shock?

. Normalization of heart rate and blood pressure
. Return of the bulbocavernosus reflex
. Return of deep tendon reflexes in the lower extremities
. Voluntary anal sphincter contraction
. Withdrawal to pain in the lower extremities

Correct Answer & Explanation

. Return of the bulbocavernosus reflex

Explanation

The return of the bulbocavernosus reflex marks the end of spinal shock, which is a temporary state of physiologic spinal cord depression. The patient's concurrent bradycardia and hypotension actually suggest neurogenic shock, a distinct dysautonomic phenomenon.

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