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6. Spine MCQs

Practice Set 298 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 5941

Topic: 6. Spine

A 78-year-old male undergoes a revision total hip arthroplasty. On post-operative day 1, his blood pressure is 85/50 mmHg despite receiving 2 liters of crystalloid. His heart rate is 110 bpm, and he is cool and clammy. His hemoglobin is 9.5 g/dL (pre-op 13.0 g/dL). What is the most likely cause of his persistent hypotension?

. Anaphylaxis
. Surgical site hematoma with ongoing blood loss
. Spinal shock
. Sepsis
. Myocardial infarction

Correct Answer & Explanation

. Surgical site hematoma with ongoing blood loss

Explanation

A significant drop in hemoglobin from 13.0 to 9.5 g/dL post-operatively, coupled with persistent hypotension, tachycardia, and signs of hypoperfusion, strongly suggests ongoing blood loss, most likely from a surgical site hematoma in a revision hip arthroplasty. Anaphylaxis would have other signs (rash, bronchospasm). Spinal shock typically causes bradycardia rather than tachycardia. Sepsis is possible but usually takes longer to manifest profoundly, and the hemoglobin drop points away from it as the primary acute cause. Myocardial infarction is a possibility but usually associated with chest pain or ECG changes and may not explain the significant hemoglobin drop.

Question 5942

Topic: 6. Spine

A 45-year-old male with a burst fracture of L1 is undergoing posterior spinal fusion. During the procedure, the blood pressure drops to 80/40 mmHg and heart rate is 50 bpm. The surgical field is dry, and estimated blood loss is minimal. The patient received a spinal anesthetic. What is the most appropriate initial pharmacological intervention?

. IV Epinephrine
. IV Phenylephrine
. IV Atropine
. IV Norepinephrine
. IV Bolus of crystalloid (1L)

Correct Answer & Explanation

. IV Phenylephrine

Explanation

The combination of hypotension and bradycardia after a spinal anesthetic is classic for sympathetic blockade. Phenylephrine, a pure alpha-1 adrenergic agonist, is the first-line vasopressor for spinal-induced hypotension because it primarily increases systemic vascular resistance without significantly increasing heart rate (which is already low). Atropine can be added if bradycardia is severe and refractory to phenylephrine. Epinephrine and Norepinephrine are more potent and usually reserved for more severe or refractory hypotension. While a fluid bolus is often given, for significant hypotension with bradycardia, a vasopressor is usually more effective and faster-acting to restore perfusion pressure.

Question 5943

Topic: 6. Spine

A 60-year-old male receives 4 liters of 0.9% Normal Saline during an 8-hour spine surgery. Post-operatively, his serum sodium is 135 mEq/L, chloride is 115 mEq/L, and bicarbonate is 18 mEq/L. What is the likely acid-base disturbance?

. Respiratory alkalosis
. Metabolic alkalosis
. Normal anion gap metabolic acidosis (hyperchloremic)
. High anion gap metabolic acidosis
. Mixed respiratory and metabolic acidosis

Correct Answer & Explanation

. Normal anion gap metabolic acidosis (hyperchloremic)

Explanation

The administration of large volumes of 0.9% Normal Saline (which contains 154 mEq/L of chloride, higher than plasma) can lead to a hyperchloremic metabolic acidosis. The patient's serum chloride is elevated (115 mEq/L, normal 95-105 mEq/L), and bicarbonate is low (18 mEq/L, normal 22-28 mEq/L), indicating a metabolic acidosis. The anion gap (Na - (Cl + HCO3)) would be normal (135 - (115 + 18) = 2), confirming a normal anion gap, hyperchloremic metabolic acidosis. Respiratory alkalosis would have low PCO2 and high pH. Metabolic alkalosis would have high bicarbonate. High anion gap acidosis would be from lactate, ketones, etc.

Question 5944

Topic: 6. Spine

A 55-year-old female is undergoing an anterior lumbar interbody fusion (ALIF). During dissection, there is a sudden drop in blood pressure and increased pulsatile blood loss. What is the most likely major vessel injured?

. Inferior vena cava
. Aorta
. Iliac artery or vein
. Lumbar segmental artery
. Femoral artery

Correct Answer & Explanation

. Iliac artery or vein

Explanation

During anterior lumbar interbody fusion (ALIF), the approach involves dissection anterior to the spine, and the major vessels at risk are the iliac vessels (common iliac artery and vein, or their branches) as they cross the lumbar spine. Injury to these large vessels would cause a sudden, significant drop in blood pressure and pulsatile blood loss. The aorta and inferior vena cava are higher and less frequently injured during the direct approach to L4-S1. Lumbar segmental arteries are smaller and would not typically cause such a profound, sudden hemodynamic collapse. The femoral artery is distal and not in the surgical field for an ALIF.

Question 5945

Topic: 6. Spine

A 58-year-old male undergoes a spinal fusion. On post-operative day 2, he develops nausea, vomiting, and his serum sodium is 123 mEq/L. He is found to be hypothyroid (TSH 55 mU/L). What is the most appropriate initial management for his hyponatremia?

. Initiate high-dose thyroid hormone replacement
. Administer 3% hypertonic saline
. Fluid restriction to 1L/day
. Administer oral sodium chloride tablets
. Start a loop diuretic

Correct Answer & Explanation

. Fluid restriction to 1L/day

Explanation

Severe hypothyroidism can cause hyponatremia, usually by impairing free water clearance and often presenting as euvolemic or mildly hypervolemic. The primary management is fluid restriction. While thyroid hormone replacement is necessary to treat the underlying hypothyroidism, it will take time to correct the hyponatremia. 3% hypertonic saline is reserved for severe symptomatic hyponatremia, and careful consideration is needed in hypothyroid patients due to potential fluid shifts. Oral sodium tablets would not address the free water excess. Loop diuretics are not first-line for hypothyroid-induced hyponatremia.

Question 5946

Topic: 6. Spine

A 60-year-old male with a history of intravenous drug use presents with acute onset of severe low back pain, fever, and progressive bilateral leg weakness over 48 hours. He is tachycardic and febrile (39.5°C). Neurological examination reveals bilateral motor weakness (3/5) in L2-S1 distribution and a sensory level at L2. Lab work shows elevated inflammatory markers (ESR 100 mm/hr, CRP 250 mg/L) and leukocytosis. What is the most appropriate urgent diagnostic and therapeutic management?

. Empiric broad-spectrum antibiotics and MRI of the lumbar spine.
. Lumbar puncture and cerebrospinal fluid analysis.
. Conservative management with bed rest and analgesia.
. Plain radiographs of the lumbar spine and blood cultures.
. Neurosurgical consultation for immediate laminectomy.

Correct Answer & Explanation

. Empiric broad-spectrum antibiotics and MRI of the lumbar spine.

Explanation

This presentation is highly concerning for an epidural abscess with spinal cord compression, a surgical emergency. The history of IV drug use is a strong risk factor. Acute neurological deficit, fever, and elevated inflammatory markers necessitate urgent investigation and treatment. MRI of the lumbar spine is the gold standard for diagnosing epidural abscess and determining the extent of compression. Empiric broad-spectrum antibiotics should be started immediately after blood cultures are drawn, without waiting for culture results. Lumbar puncture is generally contraindicated in suspected spinal epidural abscess due to the risk of neurological deterioration or spreading the infection. Conservative management is inappropriate. Plain radiographs are typically normal in early infection and will not show an epidural abscess. While neurosurgical consultation for decompression may be needed, MRI is crucial first to localize and confirm the diagnosis.

Question 5947

Topic: Cervical Spine

In the context of anterior cervical discectomy and fusion (ACDF), what is the primary biomechanical advantage of using an anterior plate?

. To prevent dysphagia.
. To increase the rate of pseudarthrosis.
. To provide immediate stability and reduce graft extrusion.
. To facilitate posterior cervical fusion at a later stage.
. To allow for earlier return to full activity without bracing.

Correct Answer & Explanation

. To provide immediate stability and reduce graft extrusion.

Explanation

The primary biomechanical advantage of using an anterior plate in ACDF is to provide immediate stability to the construct and to reduce the risk of graft extrusion or migration. The plate compresses the bone graft or cage between the vertebral bodies, preventing dislodgement and promoting fusion. While it does contribute to stability allowing earlier mobilization, the main goal is preventing graft failure and pseudarthrosis by optimizing the mechanical environment for fusion. It does not prevent dysphagia (which can be a complication of ACDF itself), nor does it increase pseudarthrosis (it aims to decrease it). It doesn't directly facilitate posterior fusion or necessarily allow full activity without bracing (which depends on surgeon preference and patient factors).

Question 5948

Topic: 6. Spine

A 68-year-old male with a history of prostate cancer and severe degenerative scoliosis presents with new onset severe back pain and bilateral leg weakness. MRI reveals a compression fracture at T10 with severe spinal canal stenosis and epidural tumor involvement. What is the most appropriate management approach?

. Conservative management with pain medication and bracing.
. Radiation therapy alone to the T10 lesion.
. Surgical decompression and stabilization, followed by radiation therapy.
. Chemotherapy alone.
. Vertebroplasty or kyphoplasty.

Correct Answer & Explanation

. Surgical decompression and stabilization, followed by radiation therapy.

Explanation

This patient has metastatic spinal cord compression (MSCC) from prostate cancer. The presence of new or worsening neurological deficits (bilateral leg weakness) combined with severe spinal canal stenosis necessitates urgent surgical decompression and stabilization. Surgical intervention provides immediate relief of neural element compression. Following surgical decompression and stabilization, radiation therapy is typically administered to target residual tumor and provide long-term local control. Conservative management is contraindicated due to neurological compromise. Radiation therapy alone may be considered for patients without neurological deficits or with minimal compression, but not for severe stenosis and neurological compromise. Chemotherapy is systemic but won't provide urgent decompression. Vertebroplasty/kyphoplasty is for pain relief in stable compression fractures, not for fractures with neurological deficits and canal compromise.

Question 5949

Topic: 6. Spine

A 70-year-old female presents with a new onset of severe, unremitting back pain and tenderness over T12 after a minor fall. She has a history of diffuse osteopenia on DXA scan. Neurological exam is normal. What is the most appropriate initial diagnostic study?

. Plain radiographs of the thoracic spine.
. MRI of the thoracic spine with contrast.
. CT scan of the thoracic spine.
. Bone scan.
. Electromyography (EMG).

Correct Answer & Explanation

. MRI of the thoracic spine with contrast.

Explanation

While plain radiographs would typically be the initial imaging for a suspected vertebral compression fracture, given the patient's age, history of osteopenia, and new onset of severe unremitting pain after even minor trauma, it is crucial to rule out a pathological fracture due to malignancy or primary tumor, even with a normal neurological exam. An MRI of the thoracic spine with contrast is the most appropriate initial diagnostic study because it can differentiate between benign osteoporotic fractures and pathological fractures (tumor, infection), and can identify spinal cord or nerve root compression more definitively than plain films or CT. Bone scans are sensitive for metastases but not specific for the underlying cause of fracture, and don't show soft tissue/neural compression. EMG is for nerve function assessment.

Question 5950

Topic: 6. Spine

Which of the following statements regarding osteomyelitis of the spine (spondylodiscitis) in adults is TRUE?

. It primarily affects the posterior elements of the vertebrae.
. Staphylococcus epidermidis is the most common causative organism.
. Patients typically present with severe neurological deficits at diagnosis.
. MRI with contrast is the gold standard for diagnosis.
. Antibiotics alone are usually sufficient for treatment, even with neurological compromise.

Correct Answer & Explanation

. MRI with contrast is the gold standard for diagnosis.

Explanation

MRI with contrast is indeed the gold standard for diagnosing spondylodiscitis, as it can accurately identify infection in the vertebral bodies and disc spaces, assess for epidural or paraspinal abscess formation, and detect spinal cord compression. Spondylodiscitis primarily affects the vertebral bodies and intervertebral disc spaces, not typically the posterior elements first. Staphylococcus aureus is the most common causative organism, not S. epidermidis (which is more common in implant-related infections). Patients often present with axial back pain and fever, but neurological deficits are present in a minority of cases, typically indicating more advanced disease or epidural extension. While antibiotics are crucial, surgical debridement and stabilization are often required for patients with neurological deficits, significant spinal instability, or persistent infection despite adequate antibiotic therapy.

Question 5951

Topic: 6. Spine

A 14-year-old competitive gymnast presents with chronic, diffuse lower back pain, exacerbated by hyperextension. Radiographs reveal bilateral spondylolysis at L5. Neurological exam is normal. What is the most appropriate initial management?

. Surgical repair of the pars defects with instrumentation.
. Spinal fusion at L5-S1.
. Bracing (e.g., LSO or TLSO), activity modification, and physical therapy.
. Epidural steroid injections.
. Percutaneous vertebroplasty.

Correct Answer & Explanation

. Bracing (e.g., LSO or TLSO), activity modification, and physical therapy.

Explanation

The patient's symptoms (back pain, worsened by hyperextension) and radiographic findings (bilateral L5 spondylolysis) are typical for this condition. In adolescents, especially athletes, the initial management is almost always conservative. This involves activity modification (rest from aggravating activities, particularly hyperextension), bracing (to limit extension and allow healing of the pars), and a focused physical therapy program to strengthen core and hamstring muscles. Most patients respond well to conservative care. Surgical repair or fusion is reserved for those who fail prolonged conservative management, have persistent debilitating pain, or demonstrate progression to spondylolisthesis with instability. Epidural injections are not typically indicated for spondylolysis in adolescents. Vertebroplasty is for compression fractures.

Question 5952

Topic: 6. Spine

Which of the following is considered the most common early complication of cervical spine fusion surgery?

. Spinal cord injury.
. Cerebrospinal fluid (CSF) leak.
. Pseudarthrosis.
. Dysphagia.
. Adjacent segment disease.

Correct Answer & Explanation

. Dysphagia.

Explanation

Dysphagia (difficulty swallowing) is the most common early complication of anterior cervical spine fusion surgery, occurring in up to 50% of patients acutely, though it is usually transient. It is thought to be due to direct surgical trauma, retractor pressure, edema, or nerve irritation. While CSF leak is a possible complication, it's less common than dysphagia. Spinal cord injury is rare but devastating. Pseudarthrosis and adjacent segment disease are considered later complications (failure of fusion, or degenerative changes at adjacent levels).

Question 5953

Topic: 6. Spine

A 55-year-old male with a history of intravenous drug use and recent pneumonia presents with new-onset severe back pain, fevers, and constitutional symptoms. Physical exam reveals paraspinal tenderness and a palpable mass in the right flank. MRI shows a large right psoas abscess originating from a T12-L1 spondylodiskitis. What is the most likely initial source of infection?

. Endocarditis with hematogenous spread.
. Gastrointestinal perforation.
. Tuberculosis of the spine.
. Urinary tract infection.
. Direct inoculation from drug use.

Correct Answer & Explanation

. Endocarditis with hematogenous spread.

Explanation

In a patient with intravenous drug use, pneumonia, and spondylodiskitis with a psoas abscess, endocarditis is a very common source of hematogenous spread to the spine. The bacteria (often Staphylococcus aureus) can seed the vertebral bodies. While UTI is a common source for spinal infections, and direct inoculation from drug use is possible (e.g., skin flora), endocarditis provides a systemic source that readily disseminates to the spine. GI perforation would be more likely to cause an intra-abdominal abscess rather than primary spondylodiskitis with secondary psoas involvement. Tuberculosis is a possibility but less likely in the context of acute pneumonia and IV drug use compared to endocarditis.

Question 5954

Topic: 6. Spine

A patient undergoes a posterior approach for a T8-T9 spinal fusion. Postoperatively, they develop significant atelectasis and have difficulty clearing secretions. Which of the following factors contributes most significantly to postoperative pulmonary complications in thoracic spine surgery?

. Pre-existing cardiac disease.
. Length of surgery and associated blood loss.
. Impaired diaphragmatic function due to surgical approach.
. Pain-induced splinting and reduced chest wall mechanics.
. Neurological deficit from the spinal surgery itself.

Correct Answer & Explanation

. Pain-induced splinting and reduced chest wall mechanics.

Explanation

Postoperative pain, particularly from thoracic spine surgery, significantly limits a patient's ability to take deep breaths and cough effectively (pain-induced splinting). This leads to decreased lung volumes, atelectasis, and retention of secretions, predisposing to pneumonia. While the other options can contribute to pulmonary complications, pain-induced splinting directly impairs the mechanics of breathing and cough, making it a primary and common factor after thoracic spine surgery. The posterior approach to the thoracic spine does not typically impair diaphragmatic function. Pre-existing cardiac disease and blood loss are general surgical risks, not specific to the mechanism of pulmonary dysfunction after thoracic spine surgery.

Question 5955

Topic: 6. Spine

A 60-year-old male with chronic back pain and stiffness, especially in the morning, presents with progressively worsening dysphagia. Radiographs show extensive flowing osteophytes along the anterior aspect of the thoracic spine. Which condition is most likely responsible for his symptoms?

. Ankylosing spondylitis.
. Diffuse Idiopathic Skeletal Hyperostosis (DISH).
. Osteoarthritis of the spine.
. Rheumatoid arthritis of the spine.
. Pott's disease.

Correct Answer & Explanation

. Diffuse Idiopathic Skeletal Hyperostosis (DISH).

Explanation

The patient's presentation with chronic back pain, stiffness, extensive flowing osteophytes along the anterior thoracic spine, and dysphagia is classic for Diffuse Idiopathic Skeletal Hyperostosis (DISH), also known as Forestier's disease. The large anterior osteophytes, particularly in the cervical spine (though they can be thoracic), can cause compression of the esophagus, leading to dysphagia. Ankylosing spondylitis also involves spinal stiffness and ossification, but typically affects the posterior elements and sacroiliac joints, leading to a 'bamboo spine' appearance and less commonly dysphagia as a primary complaint from osteophytes. Osteoarthritis is more focal and less extensive. Rheumatoid arthritis does not typically cause such osteophytes. Pott's disease (spinal tuberculosis) is an infectious condition with vertebral destruction, not flowing osteophytes.

Question 5956

Topic: 6. Spine

A 28-year-old construction worker presents with chronic low back pain and left leg radiculopathy. He has a history of smoking and reports a new onset of urinary hesitancy. MRI shows a large L5-S1 disc herniation with severe canal stenosis. What is the most concerning neurological finding that would prompt immediate surgical intervention?

. Foot drop.
. Diminished patellar reflex.
. Urinary retention with overflow incontinence.
. Numbness in the S1 dermatome.
. Weakness of the tibialis anterior muscle (L4 distribution).

Correct Answer & Explanation

. Urinary retention with overflow incontinence.

Explanation

Urinary retention with overflow incontinence, along with saddle anesthesia and bowel dysfunction, are cardinal signs of cauda equina syndrome. This is a surgical emergency requiring immediate decompression to prevent permanent neurological deficits. While foot drop, diminished patellar reflex, S1 numbness, and tibialis anterior weakness are significant neurological deficits, they represent radiculopathy and do not indicate the acute, widespread nerve root compression of cauda equina syndrome. Cauda equina syndrome involves multiple nerve roots (L2 to S5), affecting bladder and bowel function due to sacral nerve involvement.

Question 5957

Topic: 6. Spine
Which of the following sacral fracture patterns is most likely to cause cauda equina syndrome?
. Denis zone I (alar fracture).
. Denis zone II (foraminal fracture).
. Denis zone III (central canal fracture).
. Transverse sacral fracture below S3.
. Isolated coccyx fracture.

Correct Answer & Explanation

. Denis zone III (central canal fracture).

Explanation

Denis Zone III fractures involve the central sacral canal and are directly associated with cauda equina nerve root injuries, leading to cauda equina syndrome (e.g., bladder/bowel dysfunction, saddle anesthesia). Zone I fractures are lateral to the sacral foramina and typically do not involve the nerve roots directly. Zone II fractures involve the sacral foramina and can affect exiting nerve roots, but Zone III carries the highest risk for cauda equina syndrome due to direct central canal involvement. Transverse sacral fractures below S3 and isolated coccyx fractures are less likely to cause cauda equina syndrome as the nerve roots are generally spared or less critical at these levels.

Question 5958

Topic: 6. Spine

A 75-year-old male with a T12 spinal cord injury (SCI) due to a burst fracture presents with an increasing frequency of urinary tract infections (UTIs) and hydronephrosis on ultrasound. What is the most appropriate long-term bladder management strategy for this patient to prevent renal damage?

. Indwelling Foley catheter.
. Crede maneuver (manual bladder compression).
. Spontaneous voiding with timed intervals.
. Intermittent catheterization.
. Bladder training with fluid restriction.

Correct Answer & Explanation

. Intermittent catheterization.

Explanation

For patients with spinal cord injury and neurogenic bladder, intermittent catheterization (IC) is the gold standard for long-term bladder management. It minimizes residual urine, reduces the risk of UTIs compared to indwelling catheters, and preserves upper urinary tract function, thus preventing hydronephrosis and renal damage. Indwelling Foley catheters have a high risk of UTIs, stones, and bladder damage. Crede maneuver and spontaneous voiding are often ineffective in achieving complete emptying in neurogenic bladder, leading to high residual volumes. Bladder training is generally not effective in this patient population. Therefore, intermittent catheterization is crucial for renal preservation.

Question 5959

Topic: 6. Spine

Which of the following approaches to the thoracic spine (T1-T10) provides the most direct access for anterior column reconstruction and tumor resection, while minimizing the risk to the spinal cord?

. Posterior midline approach.
. Posterolateral approach (costotransversectomy).
. Transpedicular approach.
. Anterolateral (transthoracic) approach.
. Minimally invasive posterior approach.

Correct Answer & Explanation

. Anterolateral (transthoracic) approach.

Explanation

For anterior column reconstruction and tumor resection in the thoracic spine (T1-T10), the anterolateral (transthoracic) approach, typically via thoracotomy, provides the most direct and extensive exposure to the vertebral body and anterior elements. This allows for en bloc resection of tumors and reconstruction without significant manipulation of the spinal cord, minimizing neurological risk. Posterior and posterolateral approaches primarily address posterior and posterolateral pathology or require significant spinal cord retraction for anterior column access. Transpedicular approaches offer limited anterior access. Minimally invasive posterior approaches are also generally for posterior pathologies or indirect anterior decompression.

Question 5960

Topic: 6. Spine

Which of the following conditions affecting the spine is characterized by severe inflammation of the entheses and can lead to sacroiliitis and eventual 'bamboo spine' on radiographs, and is often associated with inflammatory bowel disease?

. Rheumatoid arthritis.
. Ankylosing spondylitis.
. Psoriatic arthritis.
. Reactive arthritis.
. Diffuse Idiopathic Skeletal Hyperostosis (DISH).

Correct Answer & Explanation

. Ankylosing spondylitis.

Explanation

Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the axial skeleton. It is characterized by inflammation of the entheses (sites where tendons/ligaments attach to bone), leading to sacroiliitis and progressive spinal fusion, culminating in the classic 'bamboo spine' appearance. AS is one of the seronegative spondyloarthropathies and has a strong association with inflammatory bowel disease (Crohn's disease and ulcerative colitis), uveitis, and psoriasis. While psoriatic arthritis and reactive arthritis are also spondyloarthropathies and can cause sacroiliitis, AS is the most archetypal condition for the described presentation. Rheumatoid arthritis primarily affects peripheral joints, and DISH is a non-inflammatory ossification condition.

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