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1. General Principles & Basic Science MCQs

Practice Set 19 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 361

Topic: 1. General Principles & Basic Science

Some of the more common risk factors that could predispose a person to developing low back pain are listed below. Which risk factor has not been implicated:

. Occupations requiring the use of jackhammers
. Being above normal bodyweight
. Cigarette or other tobacco consumption
. Female gender
. Occupations requiring the frequent operation of motor vehicles

Correct Answer & Explanation

. Female gender

Explanation

Being female has not been implicated as a risk factor in the development of low back pain. Occupations that require heavy lifting, the use of jackhammers, and operating motor vehicles, as well as the usage of tobacco products and being overweight have all been associated with a higher incidence of developing low back pain.

Question 362

Topic: 1. General Principles & Basic Science

A 43-year-old man develops pain radiating down his left leg from a far- lateral disk herniation at the L5/S1 level. Which is the most likely nerve root contributing to his discomfort:

. L2
. L3
. L4
. L5
. S1

Correct Answer & Explanation

. L5

Explanation

Typically, for a posterolateral disk herniation, the traversing or more distal nerve root is often involved. With a far-lateral disk herniation (as in this case), the exiting nerve root is usually involved. In this case, it would be the L5 nerve root.

Question 363

Topic: 1. General Principles & Basic Science

The most common presenting symptom of a patient with a thoracic disk herniation is:

. Anterior band-like chest pain
. Intrascapular pain
. Epigastric pain
. Lower extremity pain
. Lower extremity weakness

Correct Answer & Explanation

. Anterior band-like chest pain

Explanation

Brown et al reported on a series of 55 patients initially treated with conservative management. Anterior band-like chest pain occurred in 67% of his patients. Lower extremity complaints accounted for 20% and ranged from weakness (16%) to parasthesias (4%).

Question 364

Topic: Surgical Anatomy & Approaches

Discogenic low back pain is a common entity. The outer annulus fibrosus of the lumbar intervertebral disc is capable of nociception. Which nerve provides the primary innervation to the outer posterior third of the annulus fibrosus?

. Pudendal nerve
. Sinuvertebral nerve
. Sciatic nerve
. Superior gluteal nerve
. Genitofemoral nerve

Correct Answer & Explanation

. Sinuvertebral nerve

Explanation

The sinuvertebral nerve (recurrent meningeal nerve) originates from the ventral ramus and sympathetic trunk, innervating the posterior aspect of the annulus fibrosus, posterior longitudinal ligament, and anterior dura.

Question 365

Topic: 1. General Principles & Basic Science



A patient complains of lateral thigh and anterior knee pain. Examination reveals distinct weakness in knee extension against resistance and an absent patellar reflex. Sensation is decreased over the medial aspect of the lower leg. Which nerve root is most likely compressed?

. L2
. L3
. L4
. L5
. S1

Correct Answer & Explanation

. L4

Explanation

The L4 nerve root mediates the patellar reflex, supplies motor innervation to the quadriceps (knee extension), and provides sensation to the medial aspect of the lower leg.

Question 366

Topic: 1. General Principles & Basic Science

A 58-year-old diabetic patient presents with unremitting back pain, fevers, and elevated ESR and CRP. You suspect pyogenic vertebral osteomyelitis. What is the most sensitive and specific imaging modality to confirm this diagnosis?

. Plain anteroposterior and lateral radiographs
. Non-contrast Computed Tomography (CT)
. Technetium-99m bone scan
. Magnetic Resonance Imaging (MRI) with gadolinium
. Gallium-67 scan

Correct Answer & Explanation

. Magnetic Resonance Imaging (MRI) with gadolinium

Explanation

MRI with gadolinium contrast is the gold standard imaging modality for evaluating spinal infection, offering high sensitivity and specificity for discitis, osteomyelitis, and epidural abscess.

Question 367

Topic: 1. General Principles & Basic Science

The normal adult intervertebral disc is the largest avascular structure in the human body. How does the central nucleus pulposus primarily receive its essential nutritional supply?

. Direct branches off the abdominal aorta penetrating the annulus
. Vascular supply from the sinuvertebral artery
. Diffusion through the cartilaginous vertebral endplates
. Capillaries entering through the outer annulus fibrosus
. Absorption from the surrounding cerebrospinal fluid

Correct Answer & Explanation

. Diffusion through the cartilaginous vertebral endplates

Explanation

The nucleus pulposus is avascular and relies entirely on passive diffusion of nutrients and oxygen from the capillary beds of the adjacent vertebral bodies through the cartilaginous endplates.

Question 368

Topic: Surgical Anatomy & Approaches

A 40-year-old male undergoes an Anterior Lumbar Interbody Fusion (ALIF) at L5-S1. Postoperatively, he has no motor or sensory deficits in his legs. What is a specific, well-documented risk uniquely associated with this surgical approach?

. Retrograde ejaculation
. Erectile dysfunction
. Ureteral transection
. Bowel perforation
. Deep vein thrombosis

Correct Answer & Explanation

. Retrograde ejaculation

Explanation

ALIF at L5-S1 puts the superior hypogastric sympathetic plexus at risk during anterior exposure. Injury to this plexus can cause retrograde ejaculation, occurring in 1-2% of cases.

Question 369

Topic: 1. General Principles & Basic Science

A patient develops severe back pain two weeks after a lumbar discectomy. MRI suggests postoperative discitis. Which laboratory marker is the most reliable and rapid indicator for monitoring response to antibiotic therapy?

. White blood cell count (WBC)
. Erythrocyte sedimentation rate (ESR)
. C-reactive protein (CRP)
. Serial blood cultures
. Procalcitonin

Correct Answer & Explanation

. White blood cell count (WBC)

Explanation

CRP peaks within 48-72 hours of inflammation and normalizes rapidly with successful treatment, making it the most sensitive and dynamic marker to track the response to therapy. ESR can remain elevated for weeks.

Question 370

Topic: 1. General Principles & Basic Science

A 55-year-old male undergoes an MRI for chronic low back pain. The radiologist notes Modic Type 1 changes at the L4-L5 vertebral endplates. What do these changes represent histologically?

. Fatty replacement of the subchondral bone marrow
. Bone marrow edema and active inflammation
. Sclerotic bone formation
. Normal age-related calcification of the endplate

Correct Answer & Explanation

. Bone marrow edema and active inflammation

Explanation

Modic Type 1 changes (hypointense on T1, hyperintense on T2) represent bone marrow edema and inflammation. Type 2 represents fatty replacement, and Type 3 represents subchondral sclerosis.

Question 371

Topic: 1. General Principles & Basic Science

On physical examination, the umbilicus is a superficial landmark for the bifurcation of the aorta into the common iliac arteries and overlies this disk space:

. L1/L2
. L2/L3
. L3/L4
. L4/L5
. L5/S1

Correct Answer & Explanation

. L3/L4

Explanation

The umbilicus is a superficial landmark that often lies over the anterior L3/L4 disk space, which is the location of the aortic bifurcation into the common iliac arteries. Below this arterial division, in lean individuals, one can palpate the anterior bodies of L4, L5, and S1.

Question 372

Topic: 1. General Principles & Basic Science
One traditional surgery performed for the treatment of a symptomatic posterolateral lumbar disk herniation is a partial laminectomy and lumbar disk excision by means of a midline incision. What is the long-term (>2 years) success rate for relief of both leg and low back pain, respectively?
. 80% and 93%
. 93% and 80%
. 93% for both
. 80% for both
. 55% and 65%

Correct Answer & Explanation

. 93% and 80%

Explanation

The success rate following a partial laminectomy and lumbar disk excision for a posterolateral herniated disk for relief of both leg and low back pain is predictable at 93% and 80%, respectively.

Question 373

Topic: Surgical Anatomy & Approaches

When performing a neurological examination, if a surgeon has a patient resist thigh adduction against resistance, the surgeon is testing which nerve(s):

. Segmental nerves from T1-L1
. Femoral nerve
. Obturator nerve
. Sciatic nerve
. Segmental nerves from L5-S1

Correct Answer & Explanation

. Obturator nerve

Explanation

The obturator nerve innervates most of the hip adductor group, which consists of neurologic levels L2, L3, and L4.

Question 374

Topic: 1. General Principles & Basic Science

Beevor sign is a physical examination maneuver that tests the integrity of the rectus abdominus muscles that are segmentally innervated by the anterior primary divisions of the T5-T12/L1 nerve roots. When performing this test, the patient is asked to perform a partial sit-up. A positive Beevor sign is indicated by:

. Pain in the abdominal musculature
. Simultaneous raising both lower extremities
. The absence of any deviation of the umbilicus
. The presence of umbilical deviation
. Pain radiating down both lower extremities

Correct Answer & Explanation

. The presence of umbilical deviation

Explanation

When performing a sit-up, umbilical deviation due to abnormal contraction of the rectus musculature indicates either a partial or complete loss of segmental innervation to a portion of the rectus abdominus and/or paraspinal musculature. It is frequently seen in patients with certain neurological disorders such as meningomyelocele and poliomyelitis.

Question 375

Topic: 1. General Principles & Basic Science

A 32-year-old woman is diagnosed on magnetic resonance imaging with a far-lateral disk herniation at the L3/L4 level causing radiating right lower extremity discomfort across the anterior aspect of her knee with no motor or reflex abnormalities. Which of the following nerve roots is most likely affected:

. L1
. L2
. L3
. L4
. L5

Correct Answer & Explanation

. L3

Explanation

A far-lateral or foraminal disk herniation often affects the exiting or more proximal nerve root. The traversing or more distal nerve root is typically affected from a posterolateral disk herniation. In this case, the patient has a far-lateral disk herniation at the L3/L4 level resulting in L3 nerve root symptomatology.

Question 376

Topic: 1. General Principles & Basic Science

A 42-year-old male has a history of 6 months of pain in the lower thoracic region. Recently, the patient developed weakness in the right lower extremity, bladder and bowel movement. Plain x-rays were normal, but an magnetic resonance imaging (MRI) showed a posterolateral thoracic disk herniation at the level of T10-T11 (Slides 1 and 2). Which of the following is the best suggested treatment?

. Bed rest
. Thoraco-lumbar orthosis
. Laminectomy and decompression
. Diskectomy through thoracotomy or costotransverectomy
. Thoracotomy, vertebractomy, strut graft and internal fixation

Correct Answer & Explanation

. Diskectomy through thoracotomy or costotransverectomy

Explanation

Conservative treatment should be considered for patients without major neurologic deficits. Posterior laminectomy and decompression provides inadequate exposure of the herniated Disk. Vertebractomy, strut bone graft and instrumentation are no necessary. Thoracotomy and costotransversectomy are commonly used for disk herniations at the levels of T4-T12.

Question 377

Topic: 1. General Principles & Basic Science

The patient's clinical diagnosis is degenerative spondylolithesis. In what patient population is this condition most commonly symptomatic?

. Pre-teen males
. Females 40- to 70-years-old
. Males over 70-years-old
. Females 20- to 30-years-old

Correct Answer & Explanation

. Females 40- to 70-years-old

Explanation

Degenerative spondylolithesis is most frequently symptomatic in the 40- to 70-year-old age range and is six times more common in females than in males. This population appears to have enough disc degeneration and motion to become symptomatic, whereas the older population tend to have acquired enough ankylosis at the level to prevent instability symptoms.

Question 378

Topic: 1. General Principles & Basic Science

The biggest contribution to lumbar lordosis:

. Occurs mostly within the disk spaces
. Occurs mostly within the vertebral bodies
. Is normally 70°
. Decreases with increasing age
. Can be visualized best on an anteroposterior plain radiograph

Correct Answer & Explanation

. Occurs mostly within the disk spaces

Explanation

Most of the lumbar lordosis occurs within the disk spaces and not within the vertebral bodies. Normal lumbar lordosis is between 30°to 50°, increases with age, and is best visualized on a lateral plain radiograph.

Question 379

Topic: Surgical Anatomy & Approaches

C ertain physical examination maneuvers attempt to elicit tension signs. When used in the supine position, these maneuvers are designed to apply stretch or tension on the sciatic nerve and any inflamed nerve root against a herniated lumbar disk. Which of the following physical examination tests is not a tension sign maneuver:

. Lasegue sign
. McMurray sign
. Bowstring sign
. The sitting room test
. C ontralateral straight-leg raising test

Correct Answer & Explanation

. McMurray sign

Explanation

McMurray sign is used to detect a torn meniscus in the knee and will have minimal effect on the sciatic nerve. Lasegue sign is the classic straight-leg raising test. The bowstring sign is a variation of the straight-leg raising test performed with the knee in a flexed position. Digital pressure is then applied over the popliteal space in an attempt to reproduce the tension sign. The sitting room test is performed with the patient in a sitting position. The hip remains flexed at 90° while the examiner extends the ipsilateral knee. The contralateral straight-leg raising test is performed in the same manner as the straight-leg raising test except the contralateral, or nonpainful, leg is raised.

Question 380

Topic: Biology, Genetics & Bone Healing

A 9-year-old boy presents with delayed closure of cranial sutures, ability to appose his shoulders anteriorly due to absent clavicles, and a wide symphysis pubis on pelvic radiographs. Which of the following gene mutations is responsible for this condition?

. FGFR3
. COL1A1
. RUNX2 (CBFA1)
. COMP
. SOX9

Correct Answer & Explanation

. RUNX2 (CBFA1)

Explanation

The clinical presentation is classic for cleidocranial dysplasia. This condition is caused by a mutation in the RUNX2 (formerly CBFA1) gene, which is essential for osteoblast differentiation and intramembranous ossification.

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